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Sample records for alkylated aromatics

  1. Alkylation of organic aromatic compounds

    Science.gov (United States)

    Smith, L.A. Jr.

    1989-07-18

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 fig.

  2. Alkylation of organic aromatic compounds

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1989-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  3. A new strategy for aromatic ring alkylation in cylindrocyclophane biosynthesis.

    Science.gov (United States)

    Nakamura, Hitomi; Schultz, Erica E; Balskus, Emily P

    2017-08-01

    Alkylation of aromatic rings with alkyl halides is an important transformation in organic synthesis, yet an enzymatic equivalent is unknown. Here, we report that cylindrocyclophane biosynthesis in Cylindrospermum licheniforme ATCC 29412 involves chlorination of an unactivated carbon center by a novel halogenase, followed by a previously uncharacterized enzymatic dimerization reaction featuring sequential, stereospecific alkylations of resorcinol aromatic rings. Discovery of the enzymatic machinery underlying this unique biosynthetic carbon-carbon bond formation has implications for biocatalysis and metabolic engineering.

  4. Sulfonium Salts as Alkylating Agents for Palladium-Catalyzed Direct Ortho Alkylation of Anilides and Aromatic Ureas.

    Science.gov (United States)

    Simkó, Dániel Cs; Elekes, Péter; Pázmándi, Vivien; Novák, Zoltán

    2018-02-02

    A novel method for the ortho alkylation of acetanilide and aromatic urea derivatives via C-H activation was developed. Alkyl dibenzothiophenium salts are considered to be new reagents for the palladium-catalyzed C-H activation reaction, which enables the transfer of methyl and other alkyl groups from the sulfonium salt to the aniline derivatives under mild catalytic conditions.

  5. The formation of quasi-alicyclic rings in alkyl-aromatic compounds

    Science.gov (United States)

    Straka, Pavel; Buryan, Petr; Bičáková, Olga

    2018-02-01

    The alkyl side chains of n-alkyl phenols, n-alkyl benzenes and n-alkyl naphthalenes are cyclised, as demonstrated by GC measurements, FTIR spectroscopy and molecular mechanics calculations. Cyclisation occurs due to the intramolecular interaction between an aromatic ring (-δ) and a hydrogen of the terminal methyl group (+δ) of an alkyl chain. In fact, conventional molecules are not aliphatic-aromatic, but quasi-alicyclic-aromatic. With the aromatic molecules formed with a quasi-alicyclic ring, the effect of van der Waals attractive forces increases not only intramolecularly but also intermolecularly. This effect is strong in molecules with propyl and higher alkyl substituents. The increase of intermolecular van der Waals attractive forces results in bi-linearity in the GC retention time of the compounds in question, observed in the dependence of the logarithm of the relative retention time on the number of carbons in a molecule in both polar and nonpolar stationary phases with both capillary and packed columns. The role of van der Waals forces has been demonstrated using the potential energies of covalent and noncovalent interactions for 2-n-alkyl phenols, n-alkyl benzenes and 1-n-alkyl- and 2-n-alkyl naphthalenes.

  6. Modification with alkyl chains and the influence on thermal and mechanical properties of aromatic hyperbranched polyesters

    NARCIS (Netherlands)

    Schmaljohann, Dirk; Häußler, Liane; Pötschke, Petra; Voit, Brigitte I.; Loontjens, Ton J.A.

    2000-01-01

    All-aromatic hyperbranched polyesters with hydroxy endgroups were functionalized with aliphatic n-alkyl carboxylic acids. The length of the n-alkyl chain as well as the degree of modification were varied and the resulting, partially amphiphilic polymers were characterized by differential scanning

  7. Polycyclic aromatic acids are primary metabolites of alkyl-PAHs - a case study with Nereis diversicolor

    DEFF Research Database (Denmark)

    Malmquist, Linus Mattias Valdemar; Selck, Henriette; Jørgensen, Kåre Bredeli

    2015-01-01

    Although concentrations of alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) in oil-contaminated sediments are higher than those of unsubstituted PAHs, only little attention has been given to metabolism and ecotoxicity of alkyl-PAHs. In this study we demonstrated that metabolism of alkyl...... that carboxylic acid metabolites of alkyl-PAHs have the potential of constituting a new class of contaminants in marine waters that needs attention in relation to ecological risk assessments....

  8. Natural and bioremediated selective degradation of polycyclic aromatic alkyl isomers in oil-contaminated soils

    International Nuclear Information System (INIS)

    Sauer, T.C.; McCarthy, K.; Uhler, A.; Porta, A.

    1995-01-01

    In studies where 2- to 6-ring polycyclic aromatic hydrocarbons (PAHs) are determined as part of characterizing released oil constituents in environmental samples, the changes in composition of PAHs from weathering (e.g., evaporation, dissolution) and biodegradation are most often represented by PAH alkyl homologue distributions. Concentrations of PAH alkyl groups are the sum of individual PAH isomers of similar carbon number; such as for C2-naphthalenes, the C2 alkyl group consists of dimethyl and ethyl substitutions on the parent naphthalene. In weathering and degradation studies, the changes in relative concentration of the individual isomers within an alkyl group are rarely reported. In a field study of oiled soils, the authors looked at the selective losses, for a period of a year, of individual PAH alkyl isomers that occur both naturally by weathering processes and through the use of bioremediation technology. Results showed that decreases in alkyl group concentrations were not always represented by similar losses of each isomer in the alkyl group, but were often due to the preferential or selective loss of certain isomers in the group

  9. The use of polynuclear aromatic hydrocarbon (PAH) alkyl homologues in determining petroleum source identification and weathering

    International Nuclear Information System (INIS)

    Brown, J.S.; Boehm, P.D.; Sauer, T.C.; Wong, W.M.C.

    1993-01-01

    Techniques utilizing double ratio plots of selected polynuclear aromatic hydrocarbon (PAH) alkyl homologues were used to identify and distinguish crude oils and refined petroleum products from each other and to distinguish petroleum sources in complex pollutant regimes. Petroleum samples were fractionated by high performance liquid chromatography (HPLC) into saturated and aromatic (PAH) hydrocarbon fractions. The saturated hydrocarbon fractions were then analyzed by gas chromatography/flame ionization detection (GC/FID) to obtain a resolved/unresolved alkane fingerprint of each oil. The aromatic fractions of the oils were analyzed by gas chromatography/mass spectrometry (GC/MS) for PAH and selected alkyl homologues. Comparisons of the saturated hydrocarbon fingerprints indicated that some oils were indistinguishable based on the alkane fingerprint alone. Another double ratio plot of the alkyl chrysenes and alkyl dibenzothiophenes was effective in establishing the weathering of oil in environmental samples which were processed using the same analytical techniques, since the dibenzothiophenes are degraded more rapidly than the chrysenes. The application of selected ratios in oil spill source identification in complex environmental samples from Suisin Bay California and Boston Harbor are discussed. The use of ratios to measure the extent of weathering in oil spill samples from Prince William Sound and the Gulf of Alaska is examined

  10. Production of alkyl-aromatics from light oxygenates over zeolite catalysts for bio-oil refining

    Science.gov (United States)

    Hoang, Trung Q.

    in aromatic yield. Further improvement of aromatization and catalyst lifetime was also found with ZnHZSM-5 wherein the Zn evidently modifies the acidity. These model compound results show that the optimized use of zeolites for production of alkyl aromatics from light oxygenates at mild conditions may be effective for bio-oil refining.

  11. Selective side-chain oxidation of alkyl aromatic compounds catalyzed by cerium modified silver catalysts

    DEFF Research Database (Denmark)

    Beier, Matthias Josef; Schimmoeller, Bjoern; Hansen, Thomas Willum

    2010-01-01

    . In addition, flame-made catalysts were more stable against silver leaching compared to the impregnated catalysts. The structure of the silver catalysts was studied in detail both by X-ray absorption spectroscopy and transmission electron microscopy suggesting metallic silver to be required for catalytic......Silver supported on silica effectively catalyzes the aerobic side-chain oxidation of alkyl aromatic compounds under solvent-free conditions. Toluene, p-xylene, ethylbenzene and cumene were investigated as model substrates. Typically, the reaction was performed at ambient pressure; only for toluene...... an elevated pressure was required. Carboxylic acids, such as benzoic acid or p-toluic acid, additionally increased the reaction rate while CeO2 could act both as a promoter and an inhibitor depending on the substrate and the reaction conditions. Silver catalysts were prepared both by standard impregnation...

  12. Enzymic aromatization of 6-alkyl-substituted androgens, potent competitive and mechanism-based inhibitors of aromatase.

    Science.gov (United States)

    Numazawa, M; Yoshimura, A; Oshibe, M

    1998-01-01

    To gain insight into the relationships between the aromatase inhibitory activity of 6-alkyl-substituted androgens, potent competitive inhibitors, and their ability to serve as a substrate of aromatase, we studied the aromatization of a series of 6alpha- and 6beta-alkyl (methyl, ethyl, n-propyl, n-pentyl and n-heptyl)-substituted androst-4-ene-3,17-diones (ADs) and their androsta-1,4-diene-3,17-dione (ADD) derivatives with human placental aromatase, by gas chromatography-mass spectrometry. Among the inhibitors examined, ADD and its 6alpha-alkyl derivatives with alkyl functions less than three carbons long, together with 6beta-methyl ADD, are suicide substrates of aromatase. All of the steroids, except for 6beta-n-pentyl ADD and its n-heptyl analogue as well as 6beta-n-heptyl AD, were found to be converted into the corresponding 6-alkyl oestrogens. The 6-methyl steroids were aromatized most efficiently in each series, and the aromatization rate essentially decreased in proportion to the length of the 6-alkyl chains in each series, where the 6alpha-alkyl androgens were more efficient substrates than the corresponding 6beta isomers. The Vmax of 6alpha-methyl ADD was approx. 2.5-fold that of the natural substrate AD and approx. 3-fold that of the parent ADD. On the basis of this, along with the facts that the rates of a mechanism-based inactivation of aromatase by ADD and its 6alpha-methyl derivative are similar, it is implied that alignment of 6alpha-methyl ADD in the active site could favour the pathway leading to oestrogen over the inactivation pathway, compared with that of ADD. The relative apparent Km values for the androgens obtained in this study are different from the relative Ki values obtained previously, indicating that there is a difference between the ability to serve as an inhibitor and the ability to serve as a substrate in the 6-alkyl androgen series. PMID:9405288

  13. The development of new materials such MOFs for CO2 capture and alkylation of aromatic compounds

    International Nuclear Information System (INIS)

    Ravon, U.

    2010-01-01

    This thesis is a European project TOPCOMBI of 22 partners. More specifically, this work is the result of collaboration between ENI (Italy), ITQ (Spain), Repsol (Spain) and IRCELYON (France). This work consists of 2 different themes which improvements can be obtained by finding new materials tailored to the needs. The global energy demands are and will be constantly rising in the coming years. In order to meet this need, new resources must be found and further optimized. Fossil fuels are among the most used resources in the world. Among this 3, natural gas appears to be the most promising point of view of energy efficiency and ecological impact. However, many gas fields cannot be treated because there are too small or too contaminated to be economically viable. One way to make them attractive is to lower the cost of purification using novel separation techniques such as the PSA system. However, there is no currently effective adsorbent to allow a viable economic cleansing. Today, the alkylation reactions represent a very important economic interest. Industrial processes are typically carried out by homogeneous acid reactions or not. Seeing the new environmental restrictions, some homogeneous catalytic processes must be replaced by heterogeneous catalytic reactions with the same yields. To do this, new materials to acid characters were used: the zeolites. However the small size of pores of these compounds prevents selective alkylation reactions of molecules too large compounds such as poly-aromatic. For twenty years, new microporous crystalline compounds have emerged: the MOFs, Metal Organic Frameworks. These compounds have the characteristic to be obtained with different metal cations and organic ligands. These combinations give a wide variety of these compounds at the level of reactivity, pore volume and pore size. In this work, we tried to get different materials with specific characteristics in order to use them in methods for purification of methane in acid

  14. Evaluation of the phototoxicity of unsubstituted and alkylated polycyclic aromatic hydrocarbons to mysid shrimp (Americamysis bahia): Validation of predictive models.

    Science.gov (United States)

    Finch, Bryson E; Marzooghi, Solmaz; Di Toro, Dominic M; Stubblefield, William A

    2017-08-01

    Crude oils are composed of an assortment of hydrocarbons, some of which are polycyclic aromatic hydrocarbons (PAHs). Polycyclic aromatic hydrocarbons are of particular interest due to their narcotic and potential phototoxic effects. Several studies have examined the phototoxicity of individual PAHs and fresh and weathered crude oils, and several models have been developed to predict PAH toxicity. Fingerprint analyses of oils have shown that PAHs in crude oils are predominantly alkylated. However, current models for estimating PAH phototoxicity assume toxic equivalence between unsubstituted (i.e., parent) and alkyl-substituted compounds. This approach may be incorrect if substantial differences in toxic potency exist between unsubstituted and substituted PAHs. The objective of the present study was to examine the narcotic and photo-enhanced toxicity of commercially available unsubstituted and alkylated PAHs to mysid shrimp (Americamysis bahia). Data were used to validate predictive models of phototoxicity based on the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap approach and to develop relative effect potencies. Results demonstrated that photo-enhanced toxicity increased with increasing methylation and that phototoxic PAH potencies vary significantly among unsubstituted compounds. Overall, predictive models based on the HOMO-LUMO gap were relatively accurate in predicting phototoxicity for unsubstituted PAHs but are limited to qualitative assessments. Environ Toxicol Chem 2017;36:2043-2049. © 2017 SETAC. © 2017 SETAC.

  15. Formation of coumarines during the degradation of alkyl substituted aromatic oil components by the yeast Trichosporon asahii.

    Science.gov (United States)

    Awe, Susanne; Mikolasch, Annett; Schauer, Frieder

    2009-10-01

    In this study, we investigated the ability of the yeast Trichosporon asahii SBUG-Y 833 to assimilate phenylalkanes with alkyl chain lengths from 7 to 12 carbon atoms, and we describe for the first time the formation of coumarines via a novel degradation pathway other than the normal terminal and ss-oxidation pathway of the alkyl residues. Besides benzoic acid and its further oxidation products, six new metabolites were identified. These were the three coumarines--4-hydroxycoumarin, 4,6-dihydroxycoumarin, 4,8-dihydroxycoumarin-and the three alkyl substituted aromatic acids--7-phenylheptanoic acid, 2-hydroxyphenylheptanoic acid, and 2-hydroxyphenylpropanoic acid. 4-Hydroxycoumarin was the main extracellular metabolite during the degradation of both odd- and even-chain phenylalkanes and was also produced during further biotransformation of 2-hydroxyphenylpropanoic acid and trans-2-hydroxycinnamic acid. Due to the ability of T. asahii to form hydroxylated coumarines, the transformation of 7-hydroxycoumarin and 2,4-dihydroxyphenylpropanoic acid was investigated. Yeast cells supplemented with 7-hydroxycoumarin formed 6,7-dihydroxycoumarin and 4,7-dihydroxycoumarin. The transformation of 2,4-dihydroxyphenylpropanoic acid yielded to 4,7-dihydroxycoumarin as the main product. All hydroxylated coumarines were continuously accumulated and are very resistant to further oxidation. The high potential of the yeast T. asahii SBUG-Y 833 to form different hydroxylated coumarines from alkylaromatics suggests possible applications in the biotechnological production of coumarine structures with medical potential as anticoagulative and antitumor pharmaceutical.

  16. Modified solution calorimetry approach for determination of vaporization and sublimation enthalpies of branched-chain aliphatic and alkyl aromatic compounds at T = 298.15 K

    International Nuclear Information System (INIS)

    Varfolomeev, Mikhail A.; Novikov, Vladimir B.; Nagrimanov, Ruslan N.; Solomonov, Boris N.

    2015-01-01

    Highlights: • Solution enthalpies of 18 branching-chain alkyl aromatic and aliphatic compounds in cyclohexane were measured. • Group contributions to the enthalpy of solvation due to branching and substitution in carbon chain were evaluated. • Modified solution calorimetry based approach for determination of vaporization/sublimation enthalpies was proposed. • This approach provides vaporization/sublimation enthalpies directly at T = 298.15 K. • Vaporization/sublimation enthalpies of 35 branched-chain alkyl aromatic and aliphatic compounds were determined. - Abstract: The enthalpies of solution, solvation and vaporization/sublimation are interrelated values combined in the simplest thermodynamic circle. Hence, experimental determination of vaporization/sublimation enthalpy can be substituted by experimentally simpler determination of solution enthalpy when solvation enthalpy is known. Previously it was found that solvation enthalpies of a wide range of unbranched aliphatic and aromatic solutes in saturated hydrocarbons are in good linear correlation with their molar refraction values. This allows to estimate the vaporization/sublimation enthalpy of any unbranched organic compound from its solution enthalpy in saturated hydrocarbon and molar refraction. In the present work this approach was modified for determination of vaporization/sublimation enthalpy of branched-chain alkyl aromatic and aliphatic compounds. Group contributions to the enthalpy of solvation due to the branching of carbon chain were evaluated. Enthalpies of solution at infinite dilution of 18 branched-chain aliphatic and alkyl aromatic compounds were measured at T = 298.15 K. Vaporization/sublimation enthalpies for 35 branched aliphatic and alkyl aromatic compounds were determined by using modified solution calorimetry approach. These values are in good agreement with available literature data on vaporization/sublimation enthalpies obtained by conventional methods.

  17. The formation of quasi-alicyclic rings in alkyl-aromatic compounds

    Czech Academy of Sciences Publication Activity Database

    Straka, Pavel; Buryan, P.; Bičáková, Olga

    2018-01-01

    Roč. 1154, 15 February (2018), s. 455-462 ISSN 0022-2860 Institutional support: RVO:67985891 Keywords : alkyl chain * retention times * molecular mechanics * Van der Waals interactions Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 1.753, year: 2016

  18. Camphor-10-sulfonic acid catalyzed condensation of 2-naphthol with aromatic/aliphatic aldehydes to 14-aryl/alkyl-14H-dibenzo[a,j]xanthenes

    Directory of Open Access Journals (Sweden)

    Kundu Kshama

    2014-01-01

    Full Text Available (±-Camphor-10-sulfonic acid (CSA catalyzed condensation of 2-naphthol with both aliphatic/aromatic aldehydes at 80°C yielded 14-alkyl/aryl-dibenzoxanthenes as the sole product in high yields. However, the same condensation with benzaldehyde at 25°C afforded a mixture of intermediate 1,1-bis-(2-hydroxynaphthylphenylmethane and 14-phenyl-dibenzoxanthene while the condensation with aliphatic aldehydes at 25°C furnished the corresponding 14-alkyl-dibenzoxanthenes as the sole product. Moreover, condensation of 2-naphthol with aromatic/aliphatic aldehydes with low catalyst loading (2 mol% was greatly accelerated under microwave irradiation to afford the corresponding 14-aryl/alkyl-dibenzoxanthenes as the sole product in high yields.

  19. Aromatic substitution in the gas phase. Alkylation of arenes by gaseous C4H9+ cations

    International Nuclear Information System (INIS)

    Cacace, F.; Ciranni, G.; Giacomello, P.

    1981-01-01

    Butyl cations, obtained in the dilute gas state from the radiolysis of butane in the pressure range from 70 to 750 torr, have been allowed to react with benzene, toluene, and their mixtures or with trace amounts of o-xylene in the gaseous system. The gas-phase butylation yields invariably sec-butylarenes, remarkably free of isomeric byproducts, namely n- and tert-butylarenes. Other alkylation experiments, where gaseous butyl cations from the reaction of butane with radiolytically formed H 3 + ions were used as reagent, confirmed the exclusive formation of sec-butylarenes. The butylation process displays the positional and substrate selectivity and the dependence of orientation on the pressure of the system, typical of other gas-phase ionic substitutions. At high pressures, orth-para orientation predominates in the sec-butylation of toluene, with a ortho:meta:para ratio of 43:30:27 at 715 torr. As the pressure is reduced, a gradual shift in favor of the thermodynamically most stable meta-substituted arenium ion is observed, leading to a ortho:meta:para ratio of 31:48:21 at 70 torr

  20. Syntheses of cytotoxic novel arctigenin derivatives bearing halogen and alkyl groups on aromatic rings.

    Science.gov (United States)

    Yamauchi, Satoshi; Wukirsari, Tuti; Ochi, Yoshiaki; Nishiwaki, Hisashi; Nishi, Kosuke; Sugahara, Takuya; Akiyama, Koichi; Kishida, Taro

    2017-09-01

    The new lignano-9,9'-lactones (α,β-dibenzyl-γ-butyrolactone lignans), which showed the higher cytotoxicity than arctigenin, were synthesized. The well-known cytotoxic arctigenin showed activity against HL-60 cells (EC 50 =12μM), however, it was inactive against HeLa cells (EC 50 >100μM). The synthesized (3,4-dichloro, 2'-butoxy)-derivative 55 and (3,4-dichloro, 4'-butyl)-derivative 66 bearing the lignano-9,9'-lactone structures showed the EC 50 values of 10μM and 9.4μM against HL-60 cells, respectively. Against HeLa cells, the EC 50 value of the derivative 66 was 27μM. By comparing the activities with the corresponding 9,9'-epoxy structure (tetrahydrofuran compounds), the importance of the lactone structure of 55 and 66 for the higher activities was shown. The substituents on the aromatic ring of the lignano-9,9'-lactones affected the cytotoxicity level, observing more than 10-fold difference. Copyright © 2017. Published by Elsevier Ltd.

  1. Literature Survey and Further Studies on the 3-Alkylation of N-Unprotected 3-Monosubstituted Oxindoles. Practical Synthesis of N-Unprotected 3,3-Disubstituted Oxindoles and Subsequent Transformations on the Aromatic Ring.

    Science.gov (United States)

    Kókai, Eszter; Simig, Gyula; Volk, Balázs

    2016-12-26

    The paper provides a comprehensive review of the base-catalysed C3-alkylation of N-unprotected-3-monosubstituted oxindoles. Based on a few, non-systematic studies described in the literature using butyllithium as the deprotonating agent, an optimized method has now been elaborated, via the corresponding lithium salt, for the selective C3-alkylation of this family of compounds. The optimal excess of butyllithium and alkylating agent, and the role of the halogen atom in the latter (alkyl bromides vs. iodides) were also studied. The alkylation protocol has also been extended to some derivatives substituted at the aromatic ring. Finally, various substituents were introduced into the aromatic ring of the N-unprotected 3,3-dialkyloxindoles obtained by this optimized method.

  2. Characterizing the parent and alkyl polycyclic aromatic hydrocarbons in the Pearl River Estuary, Daya Bay and northern South China Sea: Influence of riverine input

    International Nuclear Information System (INIS)

    Yuan, Ke; Wang, Xiaowei; Lin, Li; Zou, Shichun; Li, Yan; Yang, Qingshu; Luan, Tiangang

    2015-01-01

    Distributions of 31 parent polycyclic aromatic hydrocarbons (PAHs) and 29 alkyl PAHs in surface sediments of the Pearl River Estuary (PRE), Daya Bay (DYB) and northern South China Sea (SCS) were examined to study the influence of riverine input. It was found that the contributions of riverine input to sediment PAHs in PRE was much higher than other areas. However, higher proportion of alkyl PAHs and low molecular weight PAHs in DYB and the northern SCS was observed, indicating their different sources. Nevertheless, the sediment PAHs in PRE were heterogeneous and affected by the hydrodynamic conditions. The high molecular weight PAHs were dominant in PRE and enriched in the depositional area of suspended particular matter (SPM). Moreover, the concentration of PAHs in SPM was similar to those in surface sediments and dominated in water columns. Therefore, SPM played a very important role in transportation and distribution of PAHs in PRE. - Highlights: • EPA 16 PAHs contributed a small amount of total PAHs. • Alkyl PAHs showed different behaviors from parent PAHs. • High weight PAHs preferably indicated riverine input. • PAHs distribution in sediment was related with the suspended particle deposition. - Suspended particular matter played a very important role in distribution of PAHs in tide-dominated estuary and alkyl PAHs showed different behavior from parent PAHs

  3. A Novel and Chemoselective Process of N-Alkylation of Aromatic Nitrogen Compounds Using Quaternary Ammonium Salts as Starting Material

    Directory of Open Access Journals (Sweden)

    Carlos A. González-González

    2017-01-01

    Full Text Available The process of N-alkylation of several pyrroles, indoles, and derivative heterocycles is herein described, using quaternary ammonium salts as the source of an alkylating agent. These reactions were carried out on several heterocyclic rings with triethylbenzylammonium chloride or tetradecyltrimethylammonium bromide and an NaOH solution at 50%, leading to a chemoselective N-alkylated product and an average yield of 73%. This is an alternative process to the traditional benzylation and methylation of N-heterocycles with direct handling of alkyl halides.

  4. High-resolution IR absorption spectroscopy of polycyclic aromatic hydrocarbons in the 3 μm region: role of hydrogenation and alkylation

    Science.gov (United States)

    Maltseva, Elena; Mackie, Cameron J.; Candian, Alessandra; Petrignani, Annemieke; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

    2018-03-01

    Aim. We aim to elucidate the spectral changes in the 3 μm region that result from chemical changes in the molecular periphery of polycyclic aromatic hydrocarbons (PAHs) with extra hydrogens (H-PAHs) and methyl groups (Me-PAHs). Methods: Advanced laser spectroscopic techniques combined with mass spectrometry were applied on supersonically cooled 1,2,3,4-tetrahydronaphthalene, 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, 1,2,3,6,7,8-hexahydropyrene, 9-methylanthracene, and 9,10-dimethylanthracene, allowing us to record mass-selective and conformationally selective absorption spectra of the aromatic, aliphatic, and alkyl CH-stretches in the 3.175 - 3.636 µm region with laser-limited resolution. We compared the experimental absorption spectra with standard harmonic calculations and with second-order vibrational perturbation theory anharmonic calculations that use the SPECTRO program for treating resonances. Results: We show that anharmonicity plays an important if not dominant role, affecting not only aromatic, but also aliphatic and alkyl CH-stretch vibrations. The experimental high-resolution data lead to the conclusion that the variation in Me- and H-PAHs composition might well account for the observed variations in the 3 μm emission spectra of carbon-rich and star-forming regions. Our laboratory studies also suggest that heavily hydrogenated PAHs form a significant fraction of the carriers of IR emission in regions in which an anomalously strong 3 μm plateau is observed.

  5. Direct determination of rate constants for coupling between aromatic radical anions and alkyl and benzyl radicals by laser-flash photolysis

    DEFF Research Database (Denmark)

    Lund, T.; Christensen, P.; Wilbrandt, Robert Walter

    2003-01-01

    generated by a photoinduced electron transfer reaction between the aromatic compound A and the alkyl or benzyl triphenylborate anion RB(Ph)(3)(-). For the first time the rate constants of the coupling reaction between methyl and benzyl radicals with aromatic radical anions have been obtained. For all...... the measured coupling rate constants an average value of k(1) = 1.9 x 10(9) M-1 s(-1) was found with a relatively small variation in the coupling rates (0.8-2.9 x 10(9) M-1 s(-1)). The results demonstrate that the coupling rate k(1) is insensitive to changes in the steric and electronic properties......Coupling rates between the radicals methyl, n-, sec-, tert-butyl and benzyl (R-.) and the aromatic radical anions of 1,4-dicyanonaphthalene, 9,10-dicyanoanthracene and fluorenone (A(-.)) have been obtained using a new laser-flash photolysis method. The radicals R-. and the radical anions A(-.) were...

  6. Ruthenium-complex catalyzed N-(cyclo)alkylation of aromatic amines with diols. Selective synthesis of N-(n-hydroixyalkyl)anilines of type PhNH(CH2)nOH and of some bioactive arylpiperazines,

    NARCIS (Netherlands)

    Koten, G. van; Abbenhuis, R.A.T.M.; Boersma, J.

    1998-01-01

    A new class of well-defined neutral mono-, and dicationic ruthenium(II) complexes containing a neutral terdentate donor system [C5H3N(CH2E)(2)-2,6] (E = PPh2 (PNP) or NMe2 (NN'N)) has been found effective as catalyst precursor in N-(cyclo)alkylation reactions of aromatic amines with diols

  7. Chromatographic selectivity of poly(alkyl methacrylate-co-divinylbenzene) monolithic columns for polar aromatic compounds by pressure-driven capillary liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shu-Ling; Wang, Chih-Chieh; Fuh, Ming-Ren, E-mail: msfuh@scu.edu.tw

    2016-10-05

    In this study, divinylbenzene (DVB) was used as the cross-linker to prepare alkyl methacrylate (AlMA) monoliths for incorporating π-π interactions between the aromatic analytes and AlMA-DVB monolithic stationary phases in capillary LC analysis. Various AlMA/DVB ratios were investigated to prepare a series of 30% AlMA-DVB monolithic stationary phases in fused-silica capillaries (250-μm i.d.). The physical properties (such as porosity, permeability, and column efficiency) of the synthesized AlMA-DVB monolithic columns were investigated for characterization. Isocratic elution of phenol derivatives was first employed to evaluate the suitability of the prepared AlMA-DVB columns for small molecule separation. The run-to-run (0.16–1.20%, RSD; n = 3) and column-to-column (0.26–2.95%, RSD; n = 3) repeatabilities on retention times were also examined using the selected AlMA-DVB monolithic columns. The π-π interactions between the aromatic ring and the DVB-based stationary phase offered better recognition on polar analytes with aromatic moieties, which resulted in better separation resolution of aromatic analytes on the AlMA-DVB monolithic columns. In order to demonstrate the capability of potential environmental and/or food safety applications, eight phenylurea herbicides with single benzene ring and seven sulfonamide antibiotics with polyaromatic moieties were analyzed using the selected AlMA-DVB monolithic columns. - Highlights: • First investigation on chromatographic selectivity of AlMA-DVB monolithic columns. • Good run-to-run/column-to-column repeatability (<3%) on AlMA-DVB monolithic columns. • Efficient separation of phenylurea herbicides and sulfonamides on AlMA-DVB columns.

  8. An efficient nitration of light alkanes and the alkyl side-chain of aromatic compounds with nitrogen dioxide and nitric acid catalyzed by N-hydroxyphthalimide.

    Science.gov (United States)

    Nishiwaki, Yoshiki; Sakaguchi, Satoshi; Ishii, Yasutaka

    2002-08-09

    Nitration of light alkanes and the alkyl side-chain of aromatic compounds with NO(2) and HNO(3) was successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a catalyst under relatively mild conditions. For example, the nitration of propane with NO(2) catalyzed by NHPI at 100 degrees C for 14 h gave 2-nitropropane in good yield without formation of 1-nitropropane and cleaved products such as nitroethane and nitromethane. Various aliphatic nitroalkanes, which are difficult to prepare by conventional methods, could be selectively obtained by means of the present methodology by using NHPI as the key catalyst. In addition, the side-chain nitration of alkylbenzenes such as toluene was selectively carried out to lead to alpha-nitrotoluene without the ring nitration. The present reaction provides an efficient selective method for the nitration of light alkanes and alkylbenzenes, which has been very difficult to carry out so far.

  9. Study of polar and nonpolar substituted benzenes and aromatic isomers on carbon-coated zirconia and alkyl bonded phases.

    Science.gov (United States)

    Jackson, Paul T; Carr, Peter W

    2002-06-07

    Retention factors of polar and non-polar mono- and di-substituted benzene derivatives were measured on carbon coated zirconia (C/ZrO2) and an alkyl modified silica using water-acetonitrile mobile phases. Published data on porous graphitic carbon phases (PGC) were used to facilitate comparisons between the two types of carbon media. This work showed that retention on both C/ZrO2 and PGC is much more sensitive to the solute polarizability, dipolarity, and shape than on aliphatic phases. For simple disubstituted benzenes there was no general clear cut advantage in terms of chromatographic selectivity to using a carbon-based phase over a bonded phase silica; however, the selectivities towards such isomers are quite different on the two types of media. In contradistinction to their effect on alkyl bonded phase retention, addition of a dipolar substituent and weak hydrogen bond acceptor to a benzene ring almost always increases the solute's retention on C/ZrO2 and PGC.

  10. The retention and distribution of parent, alkylated, and N/O/S-containing polycyclic aromatic hydrocarbons on the epidermal tissue of mangrove seedlings.

    Science.gov (United States)

    Li, Ruilong; Tan, Huadong; Zhu, Yaxian; Zhang, Yong

    2017-07-01

    The polycyclic aromatic hydrocarbons (PAHs) located on the epidermal tissues showed distinctive toxic effects to root, while the retention and distribution of PAHs on mangrove seedlings poorly understood. Our results confirmed that the partition coefficients (K f ) of the PAHs retained on the epidermal tissue of mangrove roots, such as Kandelia obovata, Avicennia marina and Aegiceras corniculatum, were much higher than the Poaceae plants roots, for example wheat and maize (Wild et al., 2005). Moreover, to the parent and alkyl PAHs, a well negative correlation was observed between the surface polarity of these three species of mangrove root and the K f values (p mangrove root epidermal tissues formed larger clusters than that of on Poaceae plants, such as wheat and maize (Wild et al., 2005) due to the limitation of the suberization of the root exodermis and endodermis. After exposure of 30 d, rhizo- and endophytic bacteria degraded parts of the N/O/S-containing PAHs to medium-lifetime fluorescence substances. To our knowledge, this is the first time to assess the retention of PAHs on the epidermal tissue of mangrove root, which will improve our understanding of the root uptake PAHs process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The implications of water extractable organic matter (WEOM) on the sorption of typical parent, alkyl and N/O/S-containing polycyclic aromatic hydrocarbons (PAHs) by microplastics.

    Science.gov (United States)

    Li, Ruilong; Tan, Huadong; Zhang, Linlin; Wang, Shaopeng; Wang, Yinghui; Yu, Kefu

    2018-03-15

    Microplastics sorption of persistent organic pollutants (POPs) was the core processes that cause negative effects to biota, and their influencing factors and related mechanisms are poorly understood. In this study, we explored the impacts of water extractable organic matter (WEOM), an important source of endogenous dissolved organic matter in mangrove sediment, on the sorption coefficients of typical parent, alkyl and N/O/S-containing polycyclic aromatic hydrocarbons (PAHs) by microplastics. The presence of L-WEOM (D) impeded the PAHs sorption as the coefficients (K f ) decreased to 10.17 (μg/kg)/(μg/L) n and to 8.39 (μg/kg)/(μg/L) n for fluorene (Flu) and 1-methyl-fluorene (1-M-Flu), respectively. The K f exhibited good linear relationships with the aliphaticity of L-WEOM (p  0.05). Under the presences of L-WEOM (D), (S) and (K), the lone pair electrons of N/O/S-containing PAHs was the dominant factor contributing to the obvious difference of the K f values from the other groups. Moreover, the largest impact of L-WEOM (D) on the Flu sorption was in the case of PVC microplastics, while almost no effect was in the case of PS microplastics. The findings of our work may be helpful in improving our understanding of the role of WEOM on the sorption of PAHs to microplastics in the field mangrove sediment. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Role of Delamination in Zeolite-Catalyzed Aromatic Alkylation: UCB-3 versus 3-D Al-SSZ-70

    Energy Technology Data Exchange (ETDEWEB)

    Runnebaum, Ron C.; Ouyang, Xiaoying; Edsinga, Jeffrey A.; Rea, Thomas; Arslan, Ilke; Hwang, Son-Jong; Zones, Stacey I.; Katz, Alexander

    2014-07-03

    Delaminated zeolite UCB-3 exhibits 2.4-fold greater catalytic activity relative to its three-dimensional (3D) zeolite counterpart, Al-SSZ-70, and 2.0-fold greater activity (per catalyst mass) when compared with industrial catalyst MCM-22, for the alkylation of toluene with propylene at 523 K. The former increase is nearly equal to the observed relative increase in external surface area and acid sites upon delamination. However, at 423 K for the same reaction, UCB-3 exhibits a 3.5-fold greater catalytic activity relative to 3D Al-SSZ-70. The higher relative rate enhancement for the delaminated material at lower temperature can be elucidated on the basis of increased contributions from internal acid sites. Evidence of possible contributions from such acid sites is obtained by performing catalysis after silanation treatment, which demonstrates that although virtually all catalysis in MCM-22 occurs on the external surface, catalysis also occurs on internal sites for 3D Al-SSZ-70. The additional observed enhancement at low temperatures can therefore be rationalized by greater access to internal active sites as a result of sheet breakage during delamination. Such breakage leads to shorter characteristic internal diffusion paths and was visualized using TEM comparisons of UCB-3 and 3D Al-SSZ-70.

  13. Rapid Access to Ortho-Alkylated Vinylarenes from Aromatic Acids by Dearomatization and Tandem Decarboxylative C-H Olefination/Rearomatization.

    Science.gov (United States)

    Tsai, Hung-Chang; Huang, Yen-Hsiang; Chou, Chih-Ming

    2018-03-02

    A two-step straightforward method for the preparation of ortho-alkylated vinylarenes from readily available benzoic acids is described. The synthetic route involves the dearomatization of benzoic acids by Birch reduction providing alkylated cyclohexa-2,5-dienyl-1-carboxylic acids. The diene subsequently undergoes a decarboxylative C-H olefination followed by rearomatization to deliver ortho-alkylated vinylarene. Mechanistic studies suggest that a Pd/Ag bimetallic catalytic system is important in the tandem decarboxylative C-H olefination/rearomatization step.

  14. The Barbier-Grignard-type carbonyl alkylation using unactivated alkyl halides in water.

    Science.gov (United States)

    Keh, Charlene C K; Wei, Chunmei; Li, Chao-Jun

    2003-04-09

    The aqueous Barbier-Grignard-type alkylation of aldehydes with unactivated alkyl iodides and bromides was developed. By using a combination of zinc and cuprous iodide, catalyzed by indium(I) chloride, we successfully added tertiary, secondary, and primary alkyl halides to various aromatic aldehydes in 0.07 M aqueous Na2C2O4. A mechanistic rationale for the success of the reaction has been proposed.

  15. Pressurized liquid extraction using water/isopropanol coupled with solid-phase extraction cleanup for semivolatile organic compounds, polycyclic aromatic hydrocarbons (PAH), and alkylated PAH homolog groups in sediment

    Science.gov (United States)

    Burkhardt, M.R.; Zaugg, S.D.; Burbank, T.L.; Olson, M.C.; Iverson, J.L.

    2005-01-01

    Polycyclic aromatic hydrocarbons (PAH) are recognized as environmentally relevant for their potential adverse effects on human and ecosystem health. This paper describes a method to determine the distribution of PAH and alkylated homolog groups in sediment samples. Pressurized liquid extraction (PLE), coupled with solid-phase extraction (SPE) cleanup, was developed to decrease sample preparation time, to reduce solvent consumption, and to minimize background interferences for full-scan GC-MS analysis. Recoveries from spiked Ottawa sand, environmental stream sediment, and commercially available topsoil, fortified at 1.5-15 ??g per compound, averaged 94.6 ?? 7.8%, 90.7 ?? 5.8% and 92.8 ?? 12.8%, respectively. Initial method detection limits for single-component compounds ranged from 20 to 302 ??g/kg, based on 25 g samples. Results from 28 environmental sediment samples, excluding homologs, show 35 of 41 compounds (85.4%) were detected in at least one sample with concentrations ranging from 20 to 100,000 ??g/kg. The most frequently detected compound, 2,6-dimethylnaphthalene, was detected in 23 of the 28 (82%) environmental samples with a concentration ranging from 15 to 907 ??g/kg. The results from the 28 environmental sediment samples for the homolog series showed that 27 of 28 (96%) samples had at least one homolog series present at concentrations ranging from 20 to 89,000 ??g/kg. The most frequently detected homolog series, C2-alkylated naphthalene, was detected in 26 of the 28 (93%) environmental samples with a concentration ranging from 25 to 3900 ??g/kg. Results for a standard reference material using dichloromethane Soxhlet-based extraction also are compared. ?? 2005 Elsevier B.V. All rights reserved.

  16. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

    Science.gov (United States)

    Zuend, A.; Marcolli, C.; Booth, A. M.; Lienhard, D. M.; Soonsin, V.; Krieger, U. K.; Topping, D. O.; McFiggans, G.; Peter, T.; Seinfeld, J. H.

    2011-09-01

    We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with

  17. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

    Directory of Open Access Journals (Sweden)

    A. Zuend

    2011-09-01

    Full Text Available We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl, Br, NO3, HSO4, and SO42−. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization

  18. Polycyclic Aromatic Hydrocarbons (PAHs) produced in the combustion of fatty acid alkyl esters from different feedstocks: Quantification, statistical analysis and mechanisms of formation.

    Science.gov (United States)

    Llamas, Alberto; Al-Lal, Ana-María; García-Martínez, María-Jesús; Ortega, Marcelo F; Llamas, Juan F; Lapuerta, Magín; Canoira, Laureano

    2017-05-15

    Polycyclic Aromatic Hydrocarbons (PAHs) are pollutants of concern due to their carcinogenic and mutagenic activity. Their emissions are mainly related with the combustion or pyrolysis of the organic matter, such as in fossil fuels combustion. It is important to characterize PAHs in the combustions of biofuels due to their increasing importance in the actual energetic setting. There is a lot of research focused in PAHs emission due to the combustion in diesel engines; but only few of them have analyzed the effect of raw material and type of alcohol used in the transesterification process. Different raw materials (i.e. animal fat, palm, rapeseed, linseed, peanut, coconut, and soybean oils) have been used for obtaining FAME and FAEE. A method for measuring PAHs generated during combustion in a bomb calorimeter has been developed. Combustion was made at different oxygen pressures and the samples were taken from the bomb after each combustion. Samples were extracted and the PAHs amounts formed during combustion were analyzed by GC-MS. This research shows the statistical relationships among the 16 PAHs of concern, biodiesel composition and oxygen pressure during combustion. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Bacterial Degradation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Qing X. Li

    2009-01-01

    Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

  20. Electrochemical synthesis of alkyl nitroaromatic compounds.

    Science.gov (United States)

    Gallardo, Iluminada; Guirado, Gonzalo; Marquet, Jordi

    2003-01-24

    Alkyl nitroaromatic compounds were readily prepared via nucleophilic aromatic substitution for hydrogen or a heteroatom by electrochemical oxidation of the sigma-complex. Butyllithium and butylmagnesium chloride were used as nucleophiles, and several nitrocompounds were tested to explore the possibilities of the NASH and NASX reactions promoted electrochemically.

  1. Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin-Derived Model Phenolics.

    Science.gov (United States)

    Anderson, Eric; Crisci, Anthony; Murugappan, Karthick; Román-Leshkov, Yuriy

    2017-05-22

    Reductive catalytic fractionation of biomass has recently emerged as a powerful lignin extraction and depolymerization method to produce monomeric aromatic oxygenates in high yields. Here, bifunctional molybdenum-based polyoxometalates supported on titania (POM/TiO 2 ) are shown to promote tandem hydrodeoxygenation (HDO) and alkylation reactions, converting lignin-derived oxygenated aromatics into alkylated benzenes and alkylated phenols in high yields. In particular, anisole and 4-propylguaiacol were used as model compounds for this gas-phase study using a packed-bed flow reactor. For anisole, 30 % selectivity for alkylated aromatic compounds (54 % C-alkylation of the methoxy groups by methyl balance) with an overall 72 % selectivity for HDO at 82 % anisole conversion was observed over H 3 PMo 12 O 40 /TiO 2 at 7 h on stream. Under similar conditions, 4-propylguaiacol was mainly converted into 4-propylphenol and alkylated 4-propylphenols with a selectivity to alkylated 4-propylphenols of 42 % (77 % C-alkylation) with a total HDO selectivity to 4-propylbenzene and alkylated 4-propylbenzenes of 4 % at 92 % conversion (7 h on stream). Higher catalyst loadings pushed the 4-propylguaiacol conversion to 100 % and resulted in a higher selectivity to propylbenzene of 41 %, alkylated aromatics of 21 % and alkylated phenols of 17 % (51 % C-alkylation). The reactivity studies coupled with catalyst characterization revealed that Lewis acid sites act synergistically with neighboring Brønsted acid sites to simultaneously promote alkylation and hydrodeoxygenation activity. A reaction mechanism is proposed involving activation of the ether bond on a Lewis acid site, followed by methyl transfer and C-alkylation. Mo-based POMs represent a versatile catalytic platform to simultaneously upgrade lignin-derived oxygenated aromatics into alkylated arenes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Aromatic oligoamides with a rare ortho-connectivity

    DEFF Research Database (Denmark)

    Hjelmgaard, T.; Nielsen, John

    2013-01-01

    Even though aromatic oligoamides composed of aromatic amino acids in a "one-way sequence" attract ever increasing research interest, backbones connected through ortho-linked aromatics remain rare. Herein, we present the first synthesis and study of N-alkylated ortho-aminomethyl- benzamides termed...

  3. The light activated alkylation of glycine

    International Nuclear Information System (INIS)

    Knowles, H.S.

    2001-04-01

    The work contained in this thesis focuses on the light-initiated alkylation of the α-centre of glycine compounds. The elaboration of the glycines in this manner represents a versatile, clean and cost effective alternative to ionic routes to higher α-amino acids. Preliminary investigations demonstrated that a range of nitrogen protecting groups were compatible with the radical alkylation. A variety of solvents could also be used although solvents with easily removable hydrogen atoms were found to interfere with the alkylation. Furthermore, a number of photo-initiators were investigated and the use of di-tert-butyl peroxide was found to afford the desired phenylalanine products in up to 27% yield (54% based on recovered starting material) when toluene was used as the alkylating agent. A range of different precursor concentrations was investigated and it was found that the optimum concentration of the glycine precursor was 0.13 mol dm -3 ; the phenylalanine yields were reduced when the concentration was less than this value. Owing to the poor UV absorption by di-tert-butyl peroxide, benzophenone (an effective photosensitiser) was added to the reaction mixture and this was shown to increase the alkylation yields. The ratio of reagents which produced the highest yield of phenylalanine products was found to be 1 : 5 : 5 : 10 for glycine : di-tert-butyl peroxide : benzophenone : toluene. This produced the phenylalanine product in up to 37% yield (57% based on recovered starting material). A number of substituents. (e.g. F, Cl etc.) could be attached to the aromatic ring of the toluene alkylating agent, affording substituted phenylalanines in 5 - 36% under these conditions. The formation of chiral phenylalanine products was probed by reacting glycine precursors bearing chiral auxiliaries. However, low diastereoselectivities were observed; the d.r. ranged from 1 : 1.1 to 1 : 1.5 only when chiral ester and amide protecting groups were used. In the final chapter, the α-alkylation

  4. Interfce alkylation of ethyldiphenylphosphinylacetate

    International Nuclear Information System (INIS)

    Yarkevich, A.N.; Tsvetkov, E.N.

    1994-01-01

    The paper deals with the alkylation of the methyline group of ethyldiphenylphosphinylacetate (1) by different alkylating agents in the presence of Cs 2 CO 3 . In all cases the application of Cs 2 CO 3 results in a significant increase of reaction rate. 10 refs., 3 tabs

  5. Selective N-alkylation of amines using nitriles under hydrogenation conditions: facile synthesis of secondary and tertiary amines.

    Science.gov (United States)

    Ikawa, Takashi; Fujita, Yuki; Mizusaki, Tomoteru; Betsuin, Sae; Takamatsu, Haruki; Maegawa, Tomohiro; Monguchi, Yasunari; Sajiki, Hironao

    2012-01-14

    Nitriles were found to be highly effective alkylating reagents for the selective N-alkylation of amines under catalytic hydrogenation conditions. For the aromatic primary amines, the corresponding secondary amines were selectively obtained under Pd/C-catalyzed hydrogenation conditions. Although the use of electron poor aromatic amines or bulky nitriles showed a lower reactivity toward the reductive alkylation, the addition of NH(4)OAc enhanced the reactivity to give secondary aromatic amines in good to excellent yields. Under the same reaction conditions, aromatic nitro compounds instead of the aromatic primary amines could be directly transformed into secondary amines via a domino reaction involving the one-pot hydrogenation of the nitro group and the reductive alkylation of the amines. While aliphatic amines were effectively converted to the corresponding tertiary amines under Pd/C-catalyzed conditions, Rh/C was a highly effective catalyst for the N-monoalkylation of aliphatic primary amines without over-alkylation to the tertiary amines. Furthermore, the combination of the Rh/C-catalyzed N-monoalkylation of the aliphatic primary amines and additional Pd/C-catalyzed alkylation of the resulting secondary aliphatic amines could selectively prepare aliphatic tertiary amines possessing three different alkyl groups. According to the mechanistic studies, it seems reasonable to conclude that nitriles were reduced to aldimines before the nucleophilic attack of the amine during the first step of the reaction.

  6. Organocalcium-mediated nucleophilic alkylation of benzene.

    Science.gov (United States)

    Wilson, Andrew S S; Hill, Michael S; Mahon, Mary F; Dinoi, Chiara; Maron, Laurent

    2017-12-01

    The electrophilic aromatic substitution of a C-H bond of benzene is one of the archetypal transformations of organic chemistry. In contrast, the electron-rich π-system of benzene is highly resistant to reactions with electron-rich and negatively charged organic nucleophiles. Here, we report that this previously insurmountable electronic repulsion may be overcome through the use of sufficiently potent organocalcium nucleophiles. Calcium n -alkyl derivatives-synthesized by reaction of ethene, but-1-ene, and hex-1-ene with a dimeric calcium hydride-react with protio and deutero benzene at 60°C through nucleophilic substitution of an aromatic C-D/H bond. These reactions produce the n- alkyl benzenes with regeneration of the calcium hydride. Density functional theory calculations implicate an unstabilized Meisenheimer complex in the C-H activation transition state. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  7. Isobutane/olefin-alkylation

    Energy Technology Data Exchange (ETDEWEB)

    Waitkamp, J.; Maixner, S.

    1983-11-01

    Isobutane/olefin-alkylation - technology and reaction mechanism of a refinery process for production of high octane gasoline components: The alkylation of i-butane with olefins, especially with butenes, is a process for the conversion of light byproducts of a catalytic cracker to high quality gasoline components. Alkylate is a complex mixture of i-paraffins containing 5 to ca. 12 carbon atoms. Due to their octane numbers the four trimethylpentane isomers are the most desirable product components. Indeed, under optimum process conditions these isomers are the main products. Presently, alkylation capacity in the western world amounts to more than 40x10/sup 6/ t/a. Most units are located in the USA. Two liquid-phase processes using sulfuric acid and hydrofluoric acid, respectively, are of commercial importance. At present, there is a definite trend towards HF-alkylation. The reaction mechanism which proceeds via carbocations, is extremely complex. It is composed of a great variety of individual steps. Modern mechanistic concepts are discussed.

  8. Identify alkylation hazards

    International Nuclear Information System (INIS)

    Scott, B.

    1992-01-01

    This paper reports that extensive experience shows that alkylation plants regardless of acid catalyst choice, can be operated safely, and with minimum process risk to employees or neighbors. Both types of plants require a comprehensive and fully supported hazard management program that accounts for differing physical properties of the acids involved. Control and mitigation cost to refiners will vary considerably from plant to plant and location to location. In the author's experience, the order of magnitude costs will be about $1 to $2 million for a sulfuric acid (SA) alkylation plant, and about $10 to $15 million for a hydrofluoric acid (HF) plant. These costs include water supply systems and impoundment facilities for contaminated runoff water. The alkylation process, which chemically reacts isobutane and light olefins in the presence of a strong acid catalyst into a premium gasoline component is described

  9. Branched-Selective Intermolecular Ketone α-Alkylation with Unactivated Alkenes via an Enamide Directing Strategy.

    Science.gov (United States)

    Xing, Dong; Dong, Guangbin

    2017-10-04

    We describe a strategy for intermolecular branched-selective α-alkylation of ketones using simple alkenes as the alkylating agents. Enamides derived from isoindolin-1-one provide an excellent directing template for catalytic activation of ketone α-positions. High branched selectivity is obtained for both aliphatic and aromatic alkenes using a cationic iridium catalyst. Preliminary mechanistic study favors an Ir-C migratory insertion pathway.

  10. Transformations of aromatic hydrocarbons over zeolites

    Czech Academy of Sciences Publication Activity Database

    Voláková, Martina; Žilková, Naděžda; Čejka, Jiří

    2008-01-01

    Roč. 34, 5-7 (2008), s. 439-454 ISSN 0922-6168 R&D Projects: GA ČR GA203/05/0197; GA AV ČR 1QS400400560; GA AV ČR KJB4040402 Institutional research plan: CEZ:AV0Z40400503 Keywords : aromatic hydrocarbons * zeolites * alkylation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.514, year: 2008

  11. Elementary steps and reaction pathways in the aqueous phase alkylation of phenol with ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Eckstein, Sebastian; Hintermeier, Peter H.; Olarte, Mariefel V.; Liu, Yue; Baráth, Eszter; Lercher, Johannes A.

    2017-08-01

    The hydronium ion normalized reaction rate in aqueous phase alkylation of phenol with ethanol on H-MFI zeolites increases with decreasing concentration of acid sites. Higher rates are caused by higher concentrations of phenol in the zeolite pores, as the concentration of hydronium ions generated by zeolite Brønsted acid sites decreases. Considering the different concentrations of reacting species it is shown that the intrinsic rate constant for alkylation is independent of the concentration of hydronium ions in the zeolite pores. Alkylation at the aromatic ring of phenol and of toluene as well as O-alkylation of phenol have the same activation energy, 104 ± 5 kJ/mol. This is energetic barrier to form the ethyl carbenium ion from ethanol associated to the hydronium ion. Thus, in both the reaction pathways the catalyst involves a carbenium ion, which forms a bond to a nucleophilic oxygen (ether formation) or carbon (alkylation).

  12. Comparative inhibition of tetrameric carbonyl reductase activity in pig heart cytosol by alkyl 4-pyridyl ketones.

    Science.gov (United States)

    Shimada, Hideaki; Tanigawa, Takahiro; Matayoshi, Kazunori; Katakura, Kazufumi; Babazono, Ken; Takayama, Hiroyuki; Murahashi, Tsuyoshi; Akita, Hiroyuki; Higuchi, Toshiyuki; Eto, Masashi; Imamura, Yorishige

    2014-06-01

    The present study is to elucidate the comparative inhibition of tetrameric carbonyl reductase (TCBR) activity by alkyl 4-pyridyl ketones, and to characterize its substrate-binding domain. The inhibitory effects of alkyl 4-pyridyl ketones on the stereoselective reduction of 4-benzoylpyridine (4-BP) catalyzed by TCBR were examined in the cytosolic fraction of pig heart. Of alkyl 4-pyridyl ketones, 4-hexanoylpyridine, which has a straight-chain alkyl group of five carbon atoms, inhibited most potently TCBR activity and was a competitive inhibitor. Furthermore, cyclohexyl pentyl ketone, which is substituted by cyclohexyl group instead of phenyl group of hexanophenone, had much lower ability to be reduced than hexanophenone. These results suggest that in addition to a hydrophobic cleft corresponding to a straight-chain alkyl group of five carbon atoms, a hydrophobic pocket with affinity for an aromatic group is located in the substrate-binding domain of TCBR.

  13. General Allylic C–H Alkylation with Tertiary Nucleophiles

    Science.gov (United States)

    2015-01-01

    A general method for intermolecular allylic C–H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C–H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic olefins as well as activated aromatic/heteroaromatic olefins and 1,4-dienes. The ease of appending allyl moieties onto complex scaffolds is leveraged to enable this mild and selective allylic C–H alkylation to rapidly diversify phenolic natural products. The tertiary nucleophile scope is broad and includes latent functionality for further elaboration (e.g., aliphatic alcohols, α,β-unsaturated esters). The opportunities to effect synthetic streamlining with such general C–H reactivity are illustrated in an allylic C–H alkylation/Diels–Alder reaction cascade: a reactive diene is generated via intermolecular allylic C–H alkylation and approximated to a dienophile contained within the tertiary nucleophile to furnish a common tricyclic core found in the class I galbulimima alkaloids. PMID:24641574

  14. General allylic C-H alkylation with tertiary nucleophiles.

    Science.gov (United States)

    Howell, Jennifer M; Liu, Wei; Young, Andrew J; White, M Christina

    2014-04-16

    A general method for intermolecular allylic C-H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C-H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic olefins as well as activated aromatic/heteroaromatic olefins and 1,4-dienes. The ease of appending allyl moieties onto complex scaffolds is leveraged to enable this mild and selective allylic C-H alkylation to rapidly diversify phenolic natural products. The tertiary nucleophile scope is broad and includes latent functionality for further elaboration (e.g., aliphatic alcohols, α,β-unsaturated esters). The opportunities to effect synthetic streamlining with such general C-H reactivity are illustrated in an allylic C-H alkylation/Diels-Alder reaction cascade: a reactive diene is generated via intermolecular allylic C-H alkylation and approximated to a dienophile contained within the tertiary nucleophile to furnish a common tricyclic core found in the class I galbulimima alkaloids.

  15. Aromatic graphene

    Energy Technology Data Exchange (ETDEWEB)

    Das, D. K., E-mail: gour.netai@gmail.com [Department of Metallurgical and Material Science Engineering, National Institute of Technology Durgapur-713209, West Bengal (India); Sahoo, S., E-mail: sukadevsahoo@yahoo.com [Department of Physics, National Institute of Technology Durgapur-713209, West Bengal (India)

    2016-04-13

    In recent years graphene attracts the scientific and engineering communities due to its outstanding electronic, thermal, mechanical and optical properties and many potential applications. Recently, Popov et al. [1] have studied the properties of graphene and proved that it is aromatic but without fragrance. In this paper, we present a theory to prepare graphene with fragrance. This can be used as scented pencils, perfumes, room and car fresheners, cosmetics and many other useful household substances.

  16. Aromatic graphene

    International Nuclear Information System (INIS)

    Das, D. K.; Sahoo, S.

    2016-01-01

    In recent years graphene attracts the scientific and engineering communities due to its outstanding electronic, thermal, mechanical and optical properties and many potential applications. Recently, Popov et al. [1] have studied the properties of graphene and proved that it is aromatic but without fragrance. In this paper, we present a theory to prepare graphene with fragrance. This can be used as scented pencils, perfumes, room and car fresheners, cosmetics and many other useful household substances.

  17. Method of making alkyl esters

    Science.gov (United States)

    Elliott, Brian

    2010-09-14

    Methods of making alkyl esters are described herein. The methods are capable of using raw, unprocessed, low-cost feedstocks and waste grease. Generally, the method involves converting a glyceride source to a fatty acid composition and esterifying the fatty acid composition to make alkyl esters. In an embodiment, a method of making alkyl esters comprises providing a glyceride source. The method further comprises converting the glyceride source to a fatty acid composition comprising free fatty acids and less than about 1% glyceride by mass. Moreover, the method comprises esterifying the fatty acid composition in the presence of a solid acid catalyst at a temperature ranging firm about 70.degree. C. to about 120.degree. C. to produce alkyl esters, such that at least 85% of the free fatty acids are converted to alkyl esters. The method also incorporates the use of packed bed reactors for glyceride conversion and/or fatty acid esterification to make alkyl esters.

  18. Quantitative structure-activity relationships for chronic toxicity of alkyl-chrysenes and alkyl-benz[a]anthracenes to Japanese medaka embryos (Oryzias latipes).

    Science.gov (United States)

    Lin, Hongkang; Morandi, Garrett D; Brown, R Stephen; Snieckus, Victor; Rantanen, Toni; Jørgensen, Kåre B; Hodson, Peter V

    2015-02-01

    Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are a class of compounds found at significant concentrations in crude oils, and likely the main constituents responsible for the chronic toxicity of oil to fish. Alkyl substituents at different locations on the aromatic rings change the size and shape of PAH molecules, which results in different interactions with tissue receptors and different severities of toxicity. The present study is the first to report the toxicity of several alkylated derivatives of chrysene and benz[a]anthracene to the embryos of Japanese medaka (Oryzias latipes) using the partition controlled delivery (PCD) method of exposure. The PCD method maintained the desired exposure concentrations by equilibrium partitioning of hydrophobic test compounds from polydimethylsiloxane (PDMS) films. Test concentrations declined by only 13% over a period of 17 days. Based on the prevalence of signs of blue sac disease (BSD), as expressed by median effective concentrations (EC50s), benz[a]anthracene (B[a]A) was more toxic than chrysene. Alkylation generally increased toxicity, except at position 2 of B[a]A. Alkyl-PAHs substituted in the middle region had a lower EC50 than those substituted at the distal region. Except for B[a]A and 7-methylbenz[a]anthracene (7-MB), estimated EC50 values were higher than their solubility limits, which resulted in limited toxicity within the range of test concentrations. The regression between log EC50s and logKow values provided a rough estimation of structure-activity relationships for alkyl-PAHs, but Kow alone did not provide a complete explanation of the chronic toxicity of alkyl PAHs. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. 40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl sulfates...

  20. Comparative study of oxidative stress caused by anthracene and alkyl-anthracenes in

    Directory of Open Access Journals (Sweden)

    Ji-Yeon Roh

    2018-02-01

    Full Text Available Oxidative stress was evaluated for anthracene (Ant and alkyl-Ants (9-methylanthracene [9-MA] and 9,10-dimethylanthracene [9,10-DMA] in Caenorhabditis elegans to compare changes in toxicity due to the degree of alkylation. Worms were exposed at 1 the same external exposure concentration and 2 the maximum water-soluble concentration. Formation of reactive oxygen species, superoxide dismutase activity, total glutathione concentration, and lipid peroxidation were determined under constant exposure conditions using passive dosing. The expression of oxidative stress-related genes (daf-2, sir-2.1, daf-16, sod-1, sod-2, sod-3 and cytochrome 35A/C family genes was also investigated to identify and compare changes in the genetic responses of C. elegans exposed to Ant and alkyl-Ant. At the same external concentration, 9,10-DMA induced the greatest oxidative stress, as evidenced by all indicators, except for lipid peroxidation, followed by 9-MA and Ant. Interestingly, 9,10-DMA led to greater oxidative stress than 9-MA and Ant when worms were exposed to the maximum water-soluble concentration, although the maximum water-soluble concentration of 9,10-DMA is the lowest. Increased oxidative stress by alkyl-Ants would be attributed to higher lipid-water partition coefficient and the π electron density in aromatic rings by alkyl substitution, although this supposition requires further confirmation.

  1. Equilibria and kinetics for pH-dependent axial ligation of alkyl (aquo ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 114; Issue 1. Equilibria and kinetics for H-dependent axial ligation of alkyl(aquo) cobaloximes with aromatic and aliphatic N-donor ligands. V Sridhar D Sudarshan Reddy N Ravikumar Reddy S Satyanarayana. Inorganic and Analytical Volume 114 Issue 1 February ...

  2. Pi-activated alcohols: an emerging class of alkylating agents for catalytic Friedel-Crafts reactions.

    Science.gov (United States)

    Bandini, Marco; Tragni, Michele

    2009-04-21

    The direct functionalization of aromatic compounds, via Friedel-Crafts alkylation reactions with alcohols, is one of the cornerstones in organic chemistry. The present emerging area deals with the recent advances in the use of pi-activated alcohols in the catalytic and stereoselective construction of benzylic stereocenters.

  3. Heterofacial alkylation of alkylenediamines by higher alkyl halides

    International Nuclear Information System (INIS)

    Semenov, V.A.; Kryshko, G.M.; Sokal'skaya, L.I.; Zhukova, N.G.

    1985-01-01

    A study of the physiochemical properties of alkylenediamines substituted by lower alkyls, showed that they possess increased complex-forming ability with respect to salts of different metals as titanium, niobium, zirconium, molybdenum, and zinc. To create a simpler method of synthesis of higher tetraaklyalkylalklyenediamines, based on the use of the accessible domestic raw material, the authors investigated the reaction of alkylenediamines with various alkyl halides. It was established that the best reagents can be obtained using alkyl bromides. It is concluded that the procedure of alkylation of alkylenediamines by higher alkyl halides in the presence of water developed permits the production of terraalkylalkylenediamines in one step with good yield and with purity acceptable for use as extraction reagents

  4. 4-Alkyl radical extrusion in the cytochrome P-450-catalyzed oxidation of 4-alkyl-1,4-dihydropyridines

    International Nuclear Information System (INIS)

    Lee, J.S.; Jacobsen, N.E.; Ortiz de Montellano, P.R.

    1988-01-01

    Rat liver microsomal cytochrome P-450 oxidizes the 4-methyl, 4-ethyl (DDEP), and 4-isopropyl derivatives of 3,5-bis(carbethoxy)-2,6-dimethyl-1,4,-dihydropyridine to mixtures of the corresponding 4-alkyl and 4-dealkyl pyridines. A fraction of the total microsomal enzyme is destroyed in the process. The 4-dealkyl to 4-alkyl pyridine metabolite ratio, the extent of cytochrome P-450 destruction, and the rate of spin-trapped radical accumulation are correlated in a linear inverse manner with the homolytic or heterolytic bond energies of the 4-alkyl groups of the 4-alkyl-1,4-dihydropyridines. No isotope effects are observed on the pyridine matabolite ratio, the destruction of cytochrome P-450, or the formation of ethyl radicals when [4- 2 H]DDEP is used instead of DDEP. N-Methyl- and N-ethyl-DDEP undergo N-dealkylation rather than aromatization but N-phenyl-DDEP is oxidized to a mixture of the 4-ethyl and 4-deethyl N-phenylpyridinium metabolites. In contrast to the absence of an isotope effect in the oxidation of DDEP, the 4-deethyl to 4-ethyl N-phenylpyridinium metabolite ratio increases 6-fold when N-phenyl[4- 2 H]DDEP is used. The results support the hypothesis that cytochrome P-450 catalyzes the oxidation of dihydropyridines to radical cations and show that the radical cations decay to nonradical products by multiple, substituent-dependent, mechanisms

  5. Quantitative structure–activity relationships for chronic toxicity of alkyl-chrysenes and alkyl-benz[a]anthracenes to Japanese medaka embryos (Oryzias latipes)

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Hongkang [Department of Biology, Queen' s University, Kingston, Ontario K7L3N6 (Canada); Morandi, Garrett D. [School of Environmental Studies, Queen' s University, Kingston, Ontario K7L3N6 (Canada); Brown, R. Stephen [School of Environmental Studies, Queen' s University, Kingston, Ontario K7L3N6 (Canada); Department of Chemistry, Queen' s University, Kingston, Ontario K7L3N6 (Canada); Snieckus, Victor; Rantanen, Toni [Department of Chemistry, Queen' s University, Kingston, Ontario K7L3N6 (Canada); Jørgensen, Kåre B. [Department of Mathematics and Natural Sciences, University of Stavanger, 4036 Stavanger (Norway); Hodson, Peter V., E-mail: peter.hodson@queensu.ca [Department of Biology, Queen' s University, Kingston, Ontario K7L3N6 (Canada); School of Environmental Studies, Queen' s University, Kingston, Ontario K7L3N6 (Canada)

    2015-02-15

    Highlights: • Medaka embryos were exposed to alkyl chrysenes and benzo[a]anthracenes (BAA). • Concentrations were kept constant by partition controlled delivery. • Chrysene was not toxic within solubility limits, in contrast to BAA. • Alkylation increased the toxicity of chrysene and BAA. • Toxicity was related to hydrophobicity and to specific modes of action. - Abstract: Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are a class of compounds found at significant concentrations in crude oils, and likely the main constituents responsible for the chronic toxicity of oil to fish. Alkyl substituents at different locations on the aromatic rings change the size and shape of PAH molecules, which results in different interactions with tissue receptors and different severities of toxicity. The present study is the first to report the toxicity of several alkylated derivatives of chrysene and benz[a]anthracene to the embryos of Japanese medaka (Oryzias latipes) using the partition controlled delivery (PCD) method of exposure. The PCD method maintained the desired exposure concentrations by equilibrium partitioning of hydrophobic test compounds from polydimethylsiloxane (PDMS) films. Test concentrations declined by only 13% over a period of 17 days. Based on the prevalence of signs of blue sac disease (BSD), as expressed by median effective concentrations (EC50s), benz[a]anthracene (B[a]A) was more toxic than chrysene. Alkylation generally increased toxicity, except at position 2 of B[a]A. Alkyl-PAHs substituted in the middle region had a lower EC50 than those substituted at the distal region. Except for B[a]A and 7-methylbenz[a]anthracene (7-MB), estimated EC50 values were higher than their solubility limits, which resulted in limited toxicity within the range of test concentrations. The regression between log EC50s and log K{sub ow} values provided a rough estimation of structure–activity relationships for alkyl-PAHs, but K{sub ow} alone did not provide

  6. [Determination of aromatic polycyclic hydrocarbons during the installation of bituminous acoustic insulation panels].

    Science.gov (United States)

    Gianello, G; Marrubini, G; La Bua, R; Laurini, C; Bergamaschi, A

    2006-01-01

    Two kinds of bituminous European and Asiatic origin panels, used as acoustic insulators in the production of electrical household appliances have been analysed. The tests, made at 180 degrees C, operation temperature during the assembly phases, have been executed by sampling the smokes released during the thermal treatment, subsequently analysed by GC-MS. The results showed a marked difference between the two samples in the amount of the issued compounds, essentially constituted by alkyl-aromatic hydrocarbons, IPA and Alkyl-IPA.

  7. Poly(alkyl acrylate) nonparticles

    International Nuclear Information System (INIS)

    Kreuter, J.

    1985-01-01

    This study deals with the preparation of poly(alkyl acrylic) and poly(alkyl cyanocrylic) nanoparticles. Nonoparticles are solid colloidal particles, consisting of macromolecular materials in which drugs or biologically active materials are dissolved, entrapped, and encapsulated, and/or to which the active substance is adsorbed or attached. Poly(alkyl acrylic) nanoparticles are much more slowly biodegradable than poly(alkyl cyanoacrylate) nanoparticles, and are thus more suitable for drug delivery purposes. Poly(methyl methacrylate) is the material of choice for the use of nanoparticles as an adjuvant for vaccines and are produced by emulsifier-free polymerization in aqueous media. The polymerization, which can be initiated with gamma rays or with potassium peroxodisulfate, is described

  8. Ruthenium(II)-Catalyzed Redox-Free [3 + 2] Cycloaddition of N-Sulfonyl Aromatic Aldimines with Maleimides.

    Science.gov (United States)

    Tamizmani, Masilamani; Ramesh, Balu; Jeganmohan, Masilamani

    2018-03-13

    A ruthenium(II)-catalyzed redox-free cycloaddition of N-sulfonyl aromatic aldimines with maleimides providing 1-aminoindanes in good yields is described. Usually, maleimides reacted with substituted aromatics, affording the Michael-type ortho alkylated aromatics or 1,1-type cyclized spirosuccinimides. In the present reaction, maleimides provided 1,2-type cycloaddition products. The proposed mechanism was strongly supported by the DFT calculations and isolation of a ruthenacycle intermediate.

  9. Alkyl and aryl phosphorodiiodidites. Pt. 2

    International Nuclear Information System (INIS)

    Feshchenko, N.G.; Kostina, V.G.

    1976-01-01

    Alkyl phosphorodiiodidites are formed in the reactions of alkyl phosphorodichloridites with lithium iodide. They are stable at -60 to -50 0 . When warmed to 20 0 , they disproportionate with conversion into trialkyl phosphites and phosphorus triiodide. The latter also react together and give alkyl iodides, diphosphorus tetraiodide, and a polymer of unestablished structure. Diaryl and dialkyl phosphoriodidites are stable only in solution at low temperatures. They disproportionate in a similar way to aryl and alkyl phosphorodiiodidites. Alkyl phosphorodiiodidites react with iodine with the formation of alkyl iodides and phosphoryl iodide

  10. N-Alkylation of sulfonamides by alkyl halides in the presence of electrophilic catalysts and transformations of alkylated compounds

    Directory of Open Access Journals (Sweden)

    Larysa V. Dmitrikova

    2016-12-01

    Full Text Available Vicinal halo amines constitute an important class of compounds due to their diverse biological activity and a broad application as synthones in the production of pharmaceutical agents. The reaction of aryl- and alkylsulfonamides with 1,2-dibromo-2-phenylethane in the presence of Lewis acids (such as FeCl3 and ZnCl2 in 1,2-dichloroethane can represent one of the most efficient ways of halo amine synthesis. It has been shown that methanesulfonamides and benzylsulfonamides starting materials produced the alkylation products with good yields while p-toluenesulfonamides appeared to be less active and 6-methyl-3-nitrobenzylsulfonamides did not give the expected compounds. It has been found that synthesized vicinal halo amides can easily cyclize in alkaline conditions to give 1-sulfonylaziridines. The regioselectivity of aziridine ring opening has also been studied. It was established that strong nucleophile attacks terminal carbon which leads to the breaking-up of 1–3 bond and subsequent aziridine ring opening. In contrast, weak nucleophiles (water, potassium rhodanide, hydrogen bromide trigger the cleavage of aziridine cycle by breaking-up of 1–2 bond under acidic conditions which is in accordance with molecular orbital theory. Substituents at the aromatic ring of sulfonyl fragment do not influence on the pathway of aziridine ring opening.

  11. DNA minor groove alkylating agents.

    Science.gov (United States)

    Denny, W A

    2001-04-01

    Recent work on a number of different classes of anticancer agents that alkylate DNA in the minor groove is reviewed. There has been much work with nitrogen mustards, where attachment of the mustard unit to carrier molecules can change the normal patterns of both regio- and sequence-selectivity, from reaction primarily at most guanine N7 sites in the major groove to a few adenine N3 sites at the 3'-end of poly(A/T) sequences in the minor groove. Carrier molecules discussed for mustards are intercalators, polypyrroles, polyimidazoles, bis(benzimidazoles), polybenzamides and anilinoquinolinium salts. In contrast, similar targeting of pyrrolizidine alkylators by a variety of carriers has little effect of their patterns of alkylation (at the 2-amino group of guanine). Recent work on the pyrrolobenzodiazepine and cyclopropaindolone classes of natural product minor groove binders is also reviewed.

  12. Alkyl-benzene-sulfonates; Alkylbenzenesulfonates

    Energy Technology Data Exchange (ETDEWEB)

    Marcou, L. [Ecole Superieure de Physique et Chimie Industrielles, 75 - Paris (France)]|[CEN, Comite europeen de normalisation (France)]|[Syndicat francais des producteurs d`agents de surface et produits auxiliaires industriels (ASPA) (France)

    1998-03-01

    The alkyl-benzene-sulfonates, or sulfophenyl-4-alkanes salts, (ABS) are anionic surface agents whose chemical formula is R-C{sub 6} H{sub 4}-SO{sub 3} M (where R is an aliphatic hydro-carbonated radical and M a metal). Like most of the surface agents, the ABS are complicated mixtures of isomers and homologues, the most usual products having 10 or 13 atoms of carbons. Their chemical preparation is carried out in two steps: 1)the alkyl-benzenes production by the alkanes or alkenes condensation on benzene 2)the alkyl-benzenes sulfonation and the neutralization of the sulfonic acids. The environmental impacts of these compounds are also given. (O.M.) 11 refs.

  13. Thioimidazolium Ionic Liquids as Tunable Alkylating Agents.

    Science.gov (United States)

    Guterman, Ryan; Miao, Han; Antonietti, Markus

    2018-01-19

    Alkylating ionic liquids based on the thioimidazolium structure combine the conventional properties of ionic liquids, including low melting point and nonvolatility, with the alkylating function. Alkyl transfer occurs exclusively from the S-alkyl position, thus allowing for easy derivatization of the structure without compromising specificity. We apply this feature to tune the electrophilicty of the cation to profoundly affect the reactivity of these alkylating ionic liquids, with a caffeine-derived compound possessing the highest reactivity. Anion choice was found to affect reaction rates, with iodide anions assisting in the alkylation reaction through a "shuttling" process. The ability to tune the properties of the alkylating agent using the toolbox of ionic liquid chemistry highlights the modular nature of these compounds as a platform for alkylating agent design and integration in to future systems.

  14. How non-conventional feedstocks will affect aromatics technologies

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, E. [Clariant Produkte (Deutschland) GmbH, Muenchen (Germany)

    2013-11-01

    The abundance of non-conventional feedstocks such as coal and shale gas has begun to affect the availability of traditional base chemicals such as propylene and BTX aromatics. Although this trend is primarily fueled by the fast growing shale gas economy in the US and the abundance of coal in China, it will cause the global supply and demand situation to equilibrate across the regions. Lower demand for gasoline and consequently less aromatics rich reformate from refineries will further tighten the aromatics markets that are expected to grow at healthy rates, however. Refiners can benefit from this trend by abandoning their traditional fuel-oriented business model and becoming producers of petrochemical intermediates, with special focus on paraxylene (PX). Cheap gas from coal (via gasification) or shale reserves is an advantaged feedstock that offers a great platform to make aromatics in a cost-competitive manner, especially in regions where naphtha is in short supply. Gas condensates (LPG and naphtha) are good feedstocks for paraffin aromatization, and methanol from coal or (shale) gas can be directly converted to BTX aromatics (MTA) or alkylated with benzene or toluene to make paraxylene. Most of today's technologies for the production and upgrading of BTX aromatics and their derivatives make use of the unique properties of zeolites. (orig.)

  15. Chichibabin-type direct alkylation of pyridyl alcohols with alkyl lithium reagents.

    Science.gov (United States)

    Jeffrey, Jenna L; Sarpong, Richmond

    2012-11-02

    Direct C(6) alkylation of pyridyl alcohols can be achieved following an initial deprotonation of the hydroxy group. This transformation, which is believed to occur by a Chichibabin-type alkylation, avoids lateral deprotonation prior to pyridine ring alkylation and gives increased regioselectivity for C(6) over C(4) alkylation.

  16. Electromembrane extraction with alkylated phosphites and phosphates as supported liquid membranes

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Gjelstad, Astrid; Pedersen-Bjergaard, Stig

    2017-01-01

    A range of alkylated phosphates and phosphites were for the first time investigated as potential supported liquid membranes (SLMs) for electromembrane extraction (EME) of basic drugs from human plasma samples. Six polar basic drugs were used as model analytes for initial testing of the different...... on this observation, hydrogen-bonding interactions were hypothesized to play a dominant role in the partition of the charged polar model analytes into the SLM. The successful solvents also contained alkyl moieties equivalent to 12–18 carbon atoms. Interestingly, similar phosphates/phosphites with aromatic character...... were unsuccessful. Alkylated phosphates/phosphites with less carbon atoms resulted in high current flowing in the system, whereas similar structures with >18 carbon atoms provided very low recoveries and extremely low system-current. Based on this knowledge, an SLM of TBP mixed with 40% NPOE (2...

  17. Synthesis and evaluation of sequence-specific DNA alkylating agents: effect of alkylation subunits.

    Science.gov (United States)

    Shimizu, Tatsuhiko; Sasaki, Shunta; Minoshima, Masafumi; Shinohara, Ken-ichi; Bando, Toshikazu; Sugiyama, Hiroshi

    2006-01-01

    We have demonstrated that hairpin pyrrole (Py)- imidazole (Im) polyamide-CBI conjugates selectively alkylate predetermined sequences. In this study, we investigated the effect of alkylation subunits, for example conjugates 1-4 with three types of DNA alkylating units, and Py-Im polyamides with indole linker. Conjugate 3 and 4 selectively alkylated the predetermined sequences as described previously, while conjugates 1 and 2 alkylate at mismatched sites.

  18. Electrophilic aromatic substitution over zeolites generates Wheland-type reaction intermediates

    NARCIS (Netherlands)

    Chowdhury, Abhishek Dutta|info:eu-repo/dai/nl/412438003; Houben, Klaartje|info:eu-repo/dai/nl/269224580; Whiting, Gareth T.|info:eu-repo/dai/nl/381050025; Chung, Sangho|info:eu-repo/dai/nl/411888250; Baldus, Marc|info:eu-repo/dai/nl/314410864; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2018-01-01

    The synthesis of many industrial bulk and fine chemicals frequently involves electrophilic aromatic substitution (SEAr) reactions. The most widely practiced example of the SEAr mechanism is the zeolite-catalysed ethylation of benzene, using ethylene as an alkylating agent. However, the current

  19. Lewis Acid Assisted Nickel-Catalyzed Cross-Coupling of Aryl Methyl Ethers by C−O Bond-Cleaving Alkylation: Prevention of Undesired β-Hydride Elimination

    KAUST Repository

    Liu, Xiangqian

    2016-04-10

    In the presence of trialkylaluminum reagents, diverse aryl methyl ethers can be transformed into valuable products by C-O bond-cleaving alkylation, for the first time without the limiting β-hydride elimination. This new nickel-catalyzed dealkoxylative alkylation method enables powerful orthogonal synthetic strategies for the transformation of a variety of naturally occurring and easily accessible anisole derivatives. The directing and/or activating properties of aromatic methoxy groups are utilized first, before they are replaced by alkyl chains in a subsequent coupling process.

  20. Nickel-Catalyzed Alkoxy-Alkyl Interconversion with Alkylborane Reagents through C−O Bond Activation of Aryl and Enol Ethers

    KAUST Repository

    Guo, Lin

    2016-11-07

    A nickel-catalyzed alkylation of polycyclic aromatic methyl ethers as well as methyl enol ethers with B-alkyl 9-BBN and trialkylborane reagents that involves the cleavage of stable C(sp2)−OMe bonds is described. The transformation has a wide substrate scope and good chemoselectivity profile while proceeding under mild reaction conditions; it provides a versatile way to form C(sp2)−C(sp3) bonds that does not suffer from β-hydride elimination. Furthermore, a selective and sequential alkylation process by cleavage of inert C−O bonds is presented to demonstrate the advantage of this method.

  1. γ-radiolysis of dialkyl, alkyl-aryl and diaryl sulphones

    International Nuclear Information System (INIS)

    Bowmer, T.N.; O'Donnell, J.H.

    1981-01-01

    Dialkyl sulphones, RSO 2 R, have been considered as model compounds for the radiolysis of poly(olefin sulphone)s. They show preferential C-S scission and SO 2 elimination, attributable to the relatively low strengths of these bonds. Combination of the alkyl radicals, which are produced singly or in pairs according to whether one or two C-S scissions occur in one molecule, competes with hydrogen abstraction from sulphone molecules. The latter is favoured for single C-S scissions and as the size of the radical increases and hence its mobility decreases. An important degradation reaction in radiolysis is considered to be ionization to form the cation radical of the dialkyl sulphone, followed by a single C-S scission to produce the alkyl radical and the complementary alkyl sulphonyl cation, which may undergo scission of the remaining C-S bond to produce SO 2 . GC/MS studies of the volatile products from dimethyl sulphone have shown that radiolysis results in a complexity of fragmentation and combination reactions, involving scission of most bonds in the molecule. The variety of products has been confirmed using CD 3 SO 2 CD 3 . Radiation protection by aromatic substituents has been demonstrated and branched alkyls have been shown to give higher yields of alkanes and SO 2 than linear alkyls. (author)

  2. Complex responses to alkylating agents

    International Nuclear Information System (INIS)

    Samson, L.D.

    2003-01-01

    Using Affymetrix oligonucleotide GeneChip analysis, we previously found that, upon exposure to the simple alkylating agent methylmethane sulfonate, the transcript levels for about one third of the Saccharomyces cerevisiae genome (∼2,000 transcripts) are induced or repressed during the first hour or two after exposure. In order to determine whether the responsiveness of these genes has any relevance to the protection of cells against alkylating agents we have undertaken several follow-up studies. First, we explored the specificity of this global transcriptional response to MMS by measuring the global response of S. cerevisiae to a broad range of agents that are known to induce DNA damage. We found that each agent produced a very different mRNA transcript profile, even though the exposure doses produced similar levels of toxicity. We also found that the selection of genes that respond to MMS is highly dependent upon what cell cycle phase the cells are in at the time of exposure. Computational clustering analysis of the dataset derived from a large number of exposures identified several promoter motifs that are likely to control some of the regulons that comprise this large set of genes that are responsive to DNA damaging agents. However, it should be noted that these agents damage cellular components other than DNA, and that the responsiveness of each gene need not be in response to DNA damage per se. We have also begun to study the response of other organisms to alkylating agents, and these include E. coli, cultured mouse and human cells, and mice. Finally, we have developed a high throughput phenotypic screening method to interrogate the role of all non-essential S. cerevisiae genes (about 4,800) in protecting S. cerevisiae against the deleterious effects of alkylating agents; we have termed this analysis 'genomic phenotyping'. This study has uncovered a plethora of new pathways that play a role in the recovery of eukaryotic cells after exposure to toxic

  3. PREPARATION OF ALKYL PYROPHOSPHATE EXTRACTANTS

    Science.gov (United States)

    Levine, C.A.; Skiens, W.E.; Moore, G.R.

    1960-08-01

    A process for providing superior solvent extractants for metal recovery processes is given wherein the extractant comprises an alkyl pyrophosphoric acid ester dissolved in an organic solvent diluent. Finely divided solid P/sub 2/O/ sub 5/ is slurried in an organic solvent-diluent selected from organic solvents such as kerosene, benzene, chlorobenzene, toluene, etc. An alcohol selected from the higher alcohols having 4 to 17 carbon atoms. e.g.. hexanol-1. heptanol-3, octanol-1. 2.6-dimethyl-heptanol-4, and decanol-1, is rapidly added to the P/sub 2/O/sub 5/ slurry in the amount of about 2 moles of alcohol to 1 mole of P/sub 2/ O/sub 5/. The temperature is maintained below about 110 deg C during the course of the P/sub 2/O/sub 5/-alcohol reaction. An alkyl pyrophosphate extractant compound is formed as a consequence of the reaction process. The alkyl pyrophosphate solvent-diluent extractant phase is useful in solvent extraction metal recovery processes.

  4. Isobutane alkylation over solid catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kozorezov, Y.I.; Lisin, V.I.

    1979-05-01

    Commercial alumina modified with 6Vertical Bar3< by wt boron trifluoride was active in isobutane alkylation with ethylene in a flow reactor at 5:1 isobutane-ethylene and 5-20 min reaction time. The reaction rate was first-order in ethylene and increased with increasing temperature (20/sup 0/-80/sup 0/C) and ethylene pressure (0.2-3 atm). The calculated activation energy was 8.4 kj. Kinetic data and the activity of tert.-butyl chloride, but not ethyl chloride as alkylating agents in place of ethylene suggested a carbonium-ion chain mechanism involving both surface and gas-phase reactions. The ethylene-based yield of the alkylate decreased from 132 to 41Vertical Bar3< by wt after nine hours on stream, and its bromine number increased from 0.2 to 1 g Br/sub 2//100 ml. This inhibition was attributed to adsorption on the active acidic sites of the reaction products, particularly C/sub 10//sup +/ olefins. Catalyst stabilization could probably be achieved by selecting an appropriate solvent that would continuously desorb the inhibiting products from the catalyst surface.

  5. Graphenes–Aromatic Giants

    Indian Academy of Sciences (India)

    Graphenes - Aromatic Giants. Ivan Gutman Boris Furtula. Volume 16 Issue 12 December 2011 pp 1238-1245. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/016/12/1238-1245. Keywords. Graphenes; polycyclic aromatic hydrocarbons; polyphenyls; condensed benzenes.

  6. The Scarlet Letter of Alkylation: A Mini Review of Selective Alkylating Agents

    OpenAIRE

    Oronsky, Bryan T; Reid, Tony; Knox, Susan J; Scicinski, Jan J

    2012-01-01

    If there were a stigma scale for chemotherapy, alkylating agents would be ranked at the top of the list. The chemical term alkylation is associated with nonselective toxicity, an association that dates back to the use of nitrogen mustards during World War I as chemical warfare agents. That this stigma persists and extends to compounds that, through selectivity, attempt to “tame” the indiscriminate destructive potential of alkylation is the subject of this review. Selective alkylation, as it i...

  7. Photochemically induced oscillations of aromatic pentazadienes

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, T.; Hahn, C.; Wokaun, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Aromatic pentazadienes are used to enhance the laser induced ablation of standard polymers with low absorption in the UV. Therefore the photochemistry of substituted 1,5-diaryl-3-alkyl-1,4-pentazadiene monomers was studied with a pulsed excimer laser as irradiation source. The net photochemical reaction proceeds in an overall one-step pathway A{yields}B. Quantum yields for the laser decomposition were determined to be up to 10%. An oscillating behaviour of the absorption was found during the dark period following the irradiation. The temperature dependence of this dark reaction has been studied. An attempt to model this behaviour in terms of a non-linear coupling between heat released, heat transfer, and reaction kinetics will be described. (author) 4 figs., 4 refs.

  8. Facile alkylation of 4-nitrobenzotriazole and its platelet aggregation inhibitory activity.

    Science.gov (United States)

    Singh, Dhandeep; Silakari, Om

    2017-10-15

    We explored the facile alkylation of 4-nitrobenzotriazole under basic conditions and the synthesized derivatives were tested for their potential ADP induced platelet aggregation inhibition activity in comparison with standard drug ticagrelor (selective P2Y12 inhibitor). The nitro group at 4-position is highly activating toward alkylation reactions (under strong basic conditions) and resulted in formation of degradation product like 3-nitrobenzene-1,2-diamine which make isolation of alkyl products very difficult. We optimized the reaction under mild basic condition (potassium carbonate and DMF) which is devoid of any degradation product. This is perhaps the first report of 4-nitrobenzotriazole derivatives possessing platelet aggregation inhibitory activity. Generally activity increases with increase in length of alkyl chain and 1-alkyl positional isomers were found to be more potent than 2-alkyl isomers. The benzoyl derivative was found to be the most potent [compound 22; (4-Nitro-1H-benzotriazol-1-yl)(phenyl)methanone; IC 50 =0.65±0.10mM] which may be attributed to electronegative oxygen atom and aromatic ring. Benzyl derivatives [compound 20; 1-Benzyl-4-nitro-1H-benzotriazole; IC 50 =0.81±0.08mM, compound 21; 2-Benzyl-4-nitro-2H-benzotriazole; IC 50 =0.82±0.19mM] and sulfonyl derivative [compound 23; 1-[(4-Methylphenyl)sulfonyl]-4-nitro-1H-benzotriazole; IC 50 =0.82±0.19mM] are also found to be highly active. Furthermore, all compounds possess P2Y12 binding affinity as confirmed by VASP/P2Y12 phosphorylation assay. Copyright © 2017. Published by Elsevier Ltd.

  9. S-alkylation of soft scorpionates.

    Science.gov (United States)

    Rajasekharan-Nair, Rajeev; Moore, Dean; Chalmers, Kirsten; Wallace, Dawn; Diamond, Louise M; Darby, Lisa; Armstrong, David R; Reglinski, John; Spicer, Mark D

    2013-02-11

    The alkylation reactions of soft scorpionates are reported. The hydrotris(S-alkyl-methimazolyl)borate dications (alkyl = methyl, allyl, benzyl), which were prepared by the reaction of Tm(Me) anion and primary alkyl halides, have been isolated and structurally characterised. The reaction is, however, not universally successful. DFT analysis of these alkylation reactions (C=S versus B-H alkylation) indicates that the observed outcome is driven by kinetic factors. Extending the study to incorporate alternative imine thiones (mercaptobenzothiazole, bz; thiazoline, tz) led to the structural characterisation of di[aquo-μ-aquohydrotris(mercaptobenzothiazolyl)boratosodium], which contains sodium atoms in the κ(3)-S,S,S coordination mode. Alkylation of Na[Tbz] and Na[tzTtz] leads to decomposition resulting in the formation of the simple S-alkylated heterocycles. The analysis of the species involved in these reactions shows an inherent weakness in the B-N bond in soft scorpionates, which has implications for their use in more advanced chemistry. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Isobutane alkylation. Recent developments and future perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Hommeltoft, Sven Ivar [Haldor Topsoe A/S, Nymoellevej 55, DK-2800 Lyngby (Denmark)

    2001-11-30

    In the isobutane alkylation, alkylated gasoline is obtained which is a valuable blending component for the gasoline pool. Thereby the C{sub 3}-C{sub 4} cut from the FCC units can be extensively used. Established technologies and recent developments will be reviewed and future perspectives will be given.

  11. Amino acid nitrosation products as alkylating agents.

    Science.gov (United States)

    García-Santos, M del P; Calle, E; Casado, J

    2001-08-08

    Nitrosation reactions of alpha-, beta-, and gamma-amino acids whose reaction products can act as alkylating agents of DNA were investigated. To approach in vivo conditions for the two-step mechanism (nitrosation and alkylation), nitrosation reactions were carried out in aqueous acid conditions (mimicking the conditions of the stomach lumen) while the alkylating potential of the nitrosation products was investigated at neutral pH, as in the stomach lining cells into which such products can diffuse. These conclusions were drawn: (i) The alkylating species resulting from the nitrosation of amino acids with an -NH(2) group are the corresponding lactones; (ii) the sequence of alkylating power is: alpha-lactones > beta-lactones > gamma-lactones, coming respectively from the nitrosation of alpha-, beta-, and gamma-amino acids; and (iii) the results obtained may be useful in predicting the mutagenic effectiveness of the nitrosation products of amino acids.

  12. First results from the oil sands passive air monitoring network for polycyclic aromatic compounds.

    Science.gov (United States)

    Schuster, Jasmin K; Harner, Tom; Su, Ky; Mihele, Cristian; Eng, Anita

    2015-03-03

    Results are reported from an ongoing passive air monitoring study for polycyclic aromatic compounds (PACs) in the Athabasca oil sands region in Alberta, Canada. Polyurethane foam (PUF) disk passive air samplers were deployed for consecutive 2-month periods from November 2010 to June 2012 at 17 sites. Samples were analyzed for polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, dibenzothiophene and its alkylated derivatives (DBTs). Relative to parent PAHs, alkylated PAHs and DBTs are enriched in bitumen and therefore considered to be petrogenic markers. Concentrations in air were in the range 0.03-210 ng/m(3), 0.15-230 ng/m(3) and 0.01-61 ng/m(3) for ∑PAHs, ∑alkylated PAHs and ΣDBTs, respectively. An exponential decline of the PAC concentrations in air with distance from mining areas and related petrogenic sources was observed. The most significant exponential declines were for the alkylated PAHs and DBTs and attributed to their association with mining-related emissions and near-source deposition, due to their lower volatility and greater association with depositing particles. Seasonal trends in concentrations in air for PACs were not observed for any of the compound classes. However, a forest fire episode during April to July 2011 resulted in greatly elevated PAH levels at all passive sampling locations. Alkylated PAHs and DBTs were not elevated during the forest fire period, supporting their association with petrogenic sources. Based on the results of this study, an "Athabasca PAC profile" is proposed as a potential source marker for the oil sands region. The profile is characterized by ∑PAHs/∑Alkylated PAHs = ∼0.2 and ∑PAHs/∑DBTs = ∼5.

  13. Catalytic enantioselective synthesis of atropisomeric biaryls by a cation-directed O-alkylation

    Science.gov (United States)

    Jolliffe, John D.; Armstrong, Roly J.; Smith, Martin D.

    2017-06-01

    Axially chiral biaryls, as exemplified by 1,1‧-bi-2-naphthol (BINOL), are key components of catalysts, natural products and medicines. These materials are synthesized conventionally in enantioenriched form through metal-mediated cross coupling, de novo construction of an aromatic ring, point-to-axial chirality transfer or an atropselective transformation of an existing biaryl. Here, we report a highly enantioselective organocatalytic method for the synthesis of atropisomeric biaryls by a cation-directed O-alkylation. Treatment of racemic 1-aryl-2-tetralones with a chiral quinidine-derived ammonium salt under basic conditions in the presence of an alkylating agent leads to atropselective O-alkylation with e.r. up to 98:2. Oxidation with DDQ gives access to C2-symmetric and non-symmetric BINOL derivatives without compromising e.r. We propose that the chiral ammonium counterion differentiates between rapidly equilibrating atropisomeric enolates, leading to highly atropselective O-alkylation. This dynamic kinetic resolution process offers a general approach to the synthesis of enantioenriched atropisomeric materials.

  14. Superconductivity in aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Kubozono, Yoshihiro, E-mail: kubozono@cc.okayama-u.ac.jp [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Japan Science and Technology Agency, ACT-C, Kawaguchi 332-0012 (Japan); Goto, Hidenori; Jabuchi, Taihei [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Yokoya, Takayoshi [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Kambe, Takashi [Department of Physics, Okayama University, Okayama 700-8530 (Japan); Sakai, Yusuke; Izumi, Masanari; Zheng, Lu; Hamao, Shino; Nguyen, Huyen L.T. [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Sakata, Masafumi; Kagayama, Tomoko; Shimizu, Katsuya [Center of Science and Technology under Extreme Conditions, Osaka University, Osaka 560-8531 (Japan)

    2015-07-15

    Highlights: • Aromatic superconductor is one of core research subjects in superconductivity. Superconductivity is observed in certain metal-doped aromatic hydrocarbons. Some serious problems to be solved exist for future advancement of the research. This article shows the present status of aromatic superconductors. - Abstract: ‘Aromatic hydrocarbon’ implies an organic molecule that satisfies the (4n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (K{sub x}picene, five benzene rings). Its superconducting transition temperatures (T{sub c}’s) were 7 and 18 K. Recently, we found a new superconducting K{sub x}picene phase with a T{sub c} as high as 14 K, so we now know that K{sub x}picene possesses multiple superconducting phases. Besides K{sub x}picene, we discovered new superconductors such as Rb{sub x}picene and Ca{sub x}picene. A most serious problem is that the shielding fraction is ⩽15% for K{sub x}picene and Rb{sub x}picene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of T{sub c} that is clearly

  15. Alkylation of N-substituted 2-phenylacetamides

    Directory of Open Access Journals (Sweden)

    SLOBODAN D. PETROVIC

    2004-10-01

    Full Text Available Various N-substituted phenylacetamides were alkylated using different alkylating agents under neutral and basic conditions. Reactions were performed at different reaction temperatures and in various solvents. Also, a number of various catalysts were used including phase-transfer catalysts. Reactions were followed using GC or GC-MS technique and the presence as well as the yields of the alkylation products were established. Generally, the best yield and high selectivity in the studied reactions were achieved under basic conditions where in the certain cases some products, mostly N-product, were obtained solely in quantitative yields.

  16. N-Alkylation Using Sodium Triacetoxyborohydride with Carboxylic Acids as Alkyl Sources.

    Science.gov (United States)

    Tamura, Satoru; Sato, Keigo; Kawano, Tomikazu

    2018-01-01

    A versatile N-alkylation was performed using sodium triacetoxyborohydride and carboxylic acid as an alkyl source. The combination of these reagents furnished products different from those given previously by a similar reaction. Moreover, the mild conditions of our method allowed some functional groups to remain through the reaction, whereas they would react and be converted into other moieties in the similar reductive N-alkylation reported previously. Herein, we provide a new procedure for the preparation of various compounds containing nitrogen atoms.

  17. Polycyclic Aromatic Compounds as Anticancer Agents: Synthesis and Biological Evaluation of Methoxy Dibenzofluorene Derivatives

    Directory of Open Access Journals (Sweden)

    Bimal Krishna Banik

    2014-08-01

    Full Text Available Synthesis of a new methoxy dibenzofluorene through alkylation, cyclodehydration and aromatization in a one-pot operation is achieved for the first time. Using this hydrocarbon, a few derivatives are prepared through aromatic nitration, catalytic hydrogenation, coupling reaction with a side chain and reduction. The benzylic position of this hydrocarbon with the side chain is oxidized and reduced. Some of these derivatives have demonstrated excellent antitumor activities in vitro. This study confirms antitumor activity depends on the structures of the molecules.

  18. Highly efficient and enantioselective cyclization of aromatic imines via directed C-H bond activation.

    Science.gov (United States)

    Thalji, Reema K; Ellman, Jonathan A; Bergman, Robert G

    2004-06-16

    The first highly enantioselective catalytic reaction involving aromatic C-H bond activation is communicated. Enantioselective cyclization of aromatic ketimines containing alkenyl groups tethered at the meta position of an imine directing group has been achieved using 5 mol % [RhCl(coe)2]2 and 15 mol % of an (S)-binol-derived phosphoramidite ligand. Selectivities of up to 96% ee and up to quantitative yields were obtained. Moreover, the identified catalyst system enables the intramolecular alkylation reaction to be performed at temperatures 75 degrees C lower than our previously reported achiral system. The reaction can even be performed at room temperature for one of the optimal substrates.

  19. Classical density functional theory & simulations on a coarse-grained model of aromatic ionic liquids.

    Science.gov (United States)

    Turesson, Martin; Szparaga, Ryan; Ma, Ke; Woodward, Clifford E; Forsman, Jan

    2014-05-14

    A new classical density functional approach is developed to accurately treat a coarse-grained model of room temperature aromatic ionic liquids. Our major innovation is the introduction of charge-charge correlations, which are treated in a simple phenomenological way. We test this theory on a generic coarse-grained model for aromatic RTILs with oligomeric forms for both cations and anions, approximating 1-alkyl-3-methyl imidazoliums and BF₄⁻, respectively. We find that predictions by the new density functional theory for fluid structures at charged surfaces are very accurate, as compared with molecular dynamics simulations, across a range of surface charge densities and lengths of the alkyl chain. Predictions of interactions between charged surfaces are also presented.

  20. The in vitro screening of aromatic amides as potential inhibitors of poly (ADP-ribose) polymerase

    International Nuclear Information System (INIS)

    Brown, D.M.; Horsman, M.R.; Lee, W.W.; Brown, J.M.

    1984-01-01

    It is now well established that the chromosomal enzyme poly (ADP-ribose) polymerase (ADPRP) is involved in the repair of DNA damage caused by ionizing radiation and alkylating agents, although the mechanisms involved are still not clear. ADPRP inhibitors include thymidine, nicotinamides, benzamides and methyl xanthines. The authors have demonstrated that these compounds are effective inhibitors of X-ray-induced potentially lethal damage repair (PLDR). More recently, they have shown that the cytotoxicity of the bifunctional alkylating L-phenylalanine mustard (L-PAM) was enhanced in vitro and in vivo by 3-aminobenzamide, nicotinamide and caffeine, although in the latter case pharmacokinetic changes could have contributed to the enhanced killing. The authors have examined a series of substituted carbocyclic and heterocyclic aromatic amides as potential inhibitors of ADPRP. The effect of these compounds on ADPRP activity in vitro as well as their effect on the repair of X-ray and alkylation damage in vitro are presented

  1. Alkylation of Zwitterionic Thiooxalic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Manfred Michalik

    2001-05-01

    Full Text Available The new S-alkyl thiooxal-1-hydrazono-2-amidrazonium halides 2-4 were synthesized by reaction of the corresponding zwitterionic thiooxalic acid derivatives 1 with alkyl halides in methanol. The structures of compounds 4b and 4d were proven by X-ray structural analysis. Both compounds form an interesting intermolecular network of hydrogen bonds in the solid state.

  2. Mechanochemical N-alkylation of imides

    Directory of Open Access Journals (Sweden)

    Anamarija Briš

    2017-08-01

    Full Text Available The mechanochemical N-alkylation of imide derivatives was studied. Reactions under solvent-free conditions in a ball mill gave good yields and could be put in place of the classical solution conditions. The method is general and can be applied to various imides and alkyl halides. Phthalimides prepared under ball milling conditions were used in a mechanochemical Gabriel synthesis of amines by their reaction with 1,2-diaminoethane.

  3. EXTRACTION-CHROMATOGRAPHIC DETERMINATION OF GLUCOSE AND FRUCTOSE IN THE PRESENCE OF AROMATIC AMINO ACIDS

    Directory of Open Access Journals (Sweden)

    Y. I. Korenman

    2012-01-01

    Full Text Available The extraction of glucose and fructose from aqueous salt solutions containing aromatic amino acids (phenylalanine, tryptophan, tyrosine, hydrophilic solvents (aliphatic alcohols, alkyl acetates, ketones have been studied. The quantitative characteric of the process (the distribution coefficients, the degree of extraction, separation factors are calculeted. The dependence of distribution ratios of monosaccharides from the amino acid content in the solution has been established. A mobile phase for analysis of the concentrate by ascending thin layer chromatography have been developed.

  4. N-Alkylation by Hydrogen Autotransfer Reactions.

    Science.gov (United States)

    Ma, Xiantao; Su, Chenliang; Xu, Qing

    2016-06-01

    Owing to the importance of amine/amide derivatives in all fields of chemistry, and also the green and environmentally benign features of using alcohols as alkylating reagents, the relatively high atom economic dehydrative N-alkylation reactions of amines/amides with alcohols through hydrogen autotransfer processes have received much attention and have developed rapidly in recent decades. Various efficient homogeneous and heterogeneous transition metal catalysts, nano materials, electrochemical methods, biomimetic methods, asymmetric N-alkylation reactions, aerobic oxidative methods, and even certain transition metal-free, catalyst-free, or autocatalyzed methods, have also been developed in recent years. With a brief introduction to the background and developments in this area of research, this chapter focuses mainly on recent progress and technical and conceptual advances contributing to the development of this research in the last decade. In addition to mainstream research on homogeneous and heterogeneous transition metal-catalyzed reactions, possible mechanistic routes for hydrogen transfer and alcohol activation, which are key processes in N-alkylation reactions but seldom discussed in the past, the recent reports on computational mechanistic studies of the N-alkylation reactions, and the newly emerged N-alkylation methods based on novel alcohol activation protocols such as air-promoted reactions and transition metal-free methods, are also reviewed in this chapter. Problems and bottlenecks that remained to be solved in the field, and promising new research that deserves greater future attention and effort, are also reviewed and discussed.

  5. Alkylation of reticular polymers of ethynyl piperidol by alkyl halogen and investigation of the swelling of the products in water

    International Nuclear Information System (INIS)

    Khakimkhodjaev, S.N.; Khalikov, D.Kh.

    1999-01-01

    In the paper the results of investigation on alkylation of reticular polymer of ethyl piperidol by methyl Iodide and ethyl Iodide are adduced. It have been shown that in the first case the reaction of an alkylation proceeds up to 100% of a degree of completion. In the second case of an alkylation the highest degree of alkylation reaches only 60% which is connected with formation of secondary structures. In both cases the process of an alkylation results in deriving highly swelled system

  6. Access to Alkyl-Substituted Lactone via Photoredox-Catalyzed Alkylation/Lactonization of Unsaturated Carboxylic Acids.

    Science.gov (United States)

    Sha, Wanxing; Ni, Shengyang; Han, Jianlin; Pan, Yi

    2017-11-03

    An efficient photoredox-catalyzed alkylation/lactonization reaction of unsaturated carboxylic acids by using alkyl N-hydroxyphthalimide esters as alkylation reagents has been developed. Varieties of redox-active esters derived from aliphatic carboxylic acids were proved viable in this method, affording alkyl substituted lactones in moderate to good yields. This redox-neutral procedure features mild conditions and operational simplicity, which provides a new strategy for the synthesis of alkyl substituted lactones.

  7. On Benzene and Aromaticity

    Indian Academy of Sciences (India)

    intuition, deduction and simple experimentation also need to be retold. The creativity of scientists has an appeal that transcends the subject. Chemistry of aromatic compounds provides ample opportunities for the teacher to cover many of the above aspects. One can move from almost trivial questions to those that require ...

  8. On Benzene and Aromaticity

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 4. On Benzene and Aromaticity History and Some Folklore. M V Bhatt. General Article Volume 3 Issue 4 April 1998 pp 88-93. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/003/04/0088-0093 ...

  9. Graphenes – Aromatic Giants

    Indian Academy of Sciences (India)

    Srimath

    Polycyclic aromatic hydrocarbons (often abbreviated as PAH) are an important class of organic compounds. Students learn about them in any course on organic chemistry. The best known representatives are benzene (which, in fact, is cyclic, not polycy- clic), naphthalene, anthracene, phenanthrene and pyrene. Today.

  10. Heterocyclic Aromatics in Petroleum Coke, Snow, Lake Sediments, and Air Samples from the Athabasca Oil Sands Region.

    Science.gov (United States)

    Manzano, Carlos A; Marvin, Chris; Muir, Derek; Harner, Tom; Martin, Jonathan; Zhang, Yifeng

    2017-05-16

    The aromatic fractions of snow, lake sediment, and air samples collected during 2011-2014 in the Athabasca oil sands region were analyzed using two-dimensional gas chromatography following a nontargeted approach. Commonly monitored aromatics (parent and alkylated-polycyclic aromatic hydrocarbons and dibenzothiophenes) were excluded from the analysis, focusing mainly on other heterocyclic aromatics. The unknowns detected were classified into isomeric groups and tentatively identified using mass spectral libraries. Relative concentrations of heterocyclic aromatics were estimated and were found to decrease with distance from a reference site near the center of the developments and with increasing depth of sediments. The same heterocyclic aromatics identified in snow, lake sediments, and air were observed in extracts of delayed petroleum coke, with similar distributions. This suggests that petroleum coke particles are a potential source of heterocyclic aromatics to the local environment, but other oil sands sources must also be considered. Although the signals of these heterocyclic aromatics diminished with distance, some were detected at large distances (>100 km) in snow and surface lake sediments, suggesting that the impact of industry can extend >50 km. The list of heterocyclic aromatics and the mass spectral library generated in this study can be used for future source apportionment studies.

  11. Molecular design of sequence specific DNA alkylating agents.

    Science.gov (United States)

    Minoshima, Masafumi; Bando, Toshikazu; Shinohara, Ken-ichi; Sugiyama, Hiroshi

    2009-01-01

    Sequence-specific DNA alkylating agents have great interest for novel approach to cancer chemotherapy. We designed the conjugates between pyrrole (Py)-imidazole (Im) polyamides and DNA alkylating chlorambucil moiety possessing at different positions. The sequence-specific DNA alkylation by conjugates was investigated by using high-resolution denaturing polyacrylamide gel electrophoresis (PAGE). The results showed that polyamide chlorambucil conjugates alkylate DNA at flanking adenines in recognition sequences of Py-Im polyamides, however, the reactivities and alkylation sites were influenced by the positions of conjugation. In addition, we synthesized conjugate between Py-Im polyamide and another alkylating agent, 1-(chloromethyl)-5-hydroxy-1,2-dihydro-3H-benz[e]indole (seco-CBI). DNA alkylation reactivies by both alkylating polyamides were almost comparable. In contrast, cytotoxicities against cell lines differed greatly. These comparative studies would promote development of appropriate sequence-specific DNA alkylating polyamides against specific cancer cells.

  12. The scarlet letter of alkylation: a mini review of selective alkylating agents.

    Science.gov (United States)

    Oronsky, Bryan T; Reid, Tony; Knox, Susan J; Scicinski, Jan J

    2012-08-01

    If there were a stigma scale for chemotherapy, alkylating agents would be ranked at the top of the list. The chemical term alkylation is associated with nonselective toxicity, an association that dates back to the use of nitrogen mustards during World War I as chemical warfare agents. That this stigma persists and extends to compounds that, through selectivity, attempt to "tame" the indiscriminate destructive potential of alkylation is the subject of this review. Selective alkylation, as it is referred to herein, constitutes an extremely nascent and dynamic field in oncology. The pharmacodynamic response to this selective strategy depends on a delicate kinetic balance between specificity and the rate and extent of binding. Three representative compounds are presented: RRx-001, 3-bromopyruvate, and TH-302. The main impetus for the development of these compounds has been the avoidance of the serious complications of traditional alkylating agents; therefore, it is the thesis of this review that they should not experience stigma by association.

  13. Alkylation of isobutane with light olefins: Yields of alkylates for different olefins

    Energy Technology Data Exchange (ETDEWEB)

    Albright, L.F. [Purdue Univ., West Lafayette, IN (United States); Kranz, K.E.; Masters, K.R. [STRATCO, Inc., Leawood, KS (United States)

    1993-12-01

    For alkylation of isobutane with C{sub 3}-C{sub 5} olefins using sulfuric acid as the catalyst, the yields of alkylates with different olefins are compared as the operating conditions are changed. The results of recent pilot plant experiments with propylene, C{sub 4} olefins, and C{sub 5} olefins permit such comparisons. The yields expressed as weight of alkylate produced per 100 wt of olefin consumed varied from about 201:100 to 220:100. Weight ratios of the isobutane consumed per olefin consumed vary from about 101:100 to 120:100. differences of yield values are explained by the changes in the overall chemistry. The procedure employed to calculate yields with good accuracy is based on the analysis of the alkylate and the amount of conjunct polymers produced. Based on literature data, yields are also reported for alkylations using HF as the catalyst.

  14. Photodissociation of aromatic azides

    Science.gov (United States)

    Budyka, M. F.

    2008-08-01

    Quantitative data on the photochemical activity of aromatic azides and on the mechanism and kinetics of azido group photodissociation are analysed and described systematically for the first time. The results of quantum chemical calculations of the azide structure in the ground and lower electronically excited states and the potential energy surfaces along the reaction coordinate of the N-N2 bond dissociation are considered.

  15. Comparative embryotoxicity of phenanthrene and alkyl-phenanthrene to marine medaka (Oryzias melastigma).

    Science.gov (United States)

    Mu, Jingli; Wang, Juying; Jin, Fei; Wang, Xinhong; Hong, Huasheng

    2014-08-30

    Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are the predominant form of PAHs in oil, comprising 85-95% of total PAHs. However, little attention has been paid to these chemicals in ecological risk assessment of marine oil spill. A comparative study of the toxic effects of phenanthrene and retene (7-isopropyl-1-methylphenanthrene, an alkyl-phenanthrene) on the early life stage of marine medaka (Oryzias melastigma) was conducted. Results showed that retene was significantly more toxic than phenanthrene, and marine medaka could be more sensitive to retene than some freshwater fishes. Retene had a higher excretion rate than phenanthrene during the larvae stage. Both of compounds resulted in developmental malformation of marine medaka embryos, with phenanthrene affecting on peripheral vascular system and yolk sac, while retene affecting on cardiac tissues. The toxicity of phenanthrene might be mainly related to its anesthetic effects, and that of retene might be related to the CYP1A-mediated toxicity of its metabolites. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Microbial degradation of alkyl carbazoles in Norman Wells crude oil

    Energy Technology Data Exchange (ETDEWEB)

    Fedorak, P.M.; Westlake, D.W.S.

    1984-04-01

    Norman Wells crude oil was fractionated by sequential alumina and silicic acid column chromatography methods. The resulting nitrogen-rich fraction was analyzed by gas chromatography-mass spectrometry and showed 26 alkyl (C/sub 1/ to C/sub 5/) carbazoles to be the predominant compounds. An oil-degrading mixed bacterial culture was enriched on carbazole to enhance its ability to degrade nitrogen heterocycles. This culture was used to inoculate a series of flasks of mineral medium and Norman Wells crude oil. Residual oil was recovered from these cultures after incubation at 25/sup 0/C for various times. The nitrogen-rich fraction was analyzed by capillary gas chromatography, using a nitrogen-specific detector. Most of the C/sub 1/-, C/sub 2/-, and C/sub 3/- carbazoles and one of the C/sub 4/-isomers were degraded within 8 days. No further degradation occurred when incubation was extended to 28 days. The general order of susceptibility of the isomers to biodegradation was C/sub 1/ > C/sub 2/ > C/sub 3/ > C/sub 4/. The carbazole-enriched culture was still able to degrade n-alkanes, isoprenoids, aromatic hydrocarbons, and sulfur heterocycles in the crude soil. 26 references.

  17. Microbial Degradation of Alkyl Carbazoles in Norman Wells Crude Oil

    Science.gov (United States)

    Fedorak, Phillip M.; Westlake, Donald W. S.

    1984-01-01

    Norman Wells crude oil was fractionated by sequential alumina and silicic acid column chromatography methods. The resulting nitrogen-rich fraction was analyzed by gas chromatography-mass spectrometry and showed 26 alkyl (C1 to C5) carbazoles to be the predominant compounds. An oil-degrading mixed bacterial culture was enriched on carbazole to enhance its ability to degrade nitrogen heterocycles. This culture was used to inoculate a series of flasks of mineral medium and Norman Wells crude oil. Residual oil was recovered from these cultures after incubation at 25°C for various times. The nitrogen-rich fraction was analyzed by capillary gas chromatography, using a nitrogen-specific detector. Most of the C1-, C2-, and C3- carbazoles and one of the C4-isomers were degraded within 8 days. No further degradation occurred when incubation was extended to 28 days. The general order of susceptibility of the isomers to biodegradation was C1 > C2 > C3 > C4. The carbazole-enriched culture was still able to degrade n-alkanes, isoprenoids, aromatic hydrocarbons, and sulfur heterocycles in the crude soil. PMID:16346524

  18. Enhancement of alkylation catalysts for improved supercritical fluid regeneration

    Science.gov (United States)

    Ginosar, Daniel M.; Petkovic, Lucia M.

    2010-12-28

    A method of modifying an alkylation catalyst to reduce the formation of condensed hydrocarbon species thereon. The method comprises providing an alkylation catalyst comprising a plurality of active sites. The plurality of active sites on the alkylation catalyst may include a plurality of weakly acidic active sites, intermediate acidity active sites, and strongly acidic active sites. A base is adsorbed to a portion of the plurality of active sites, such as the strongly acidic active sites, selectively poisoning the strongly acidic active sites. A method of modifying the alkylation catalyst by providing an alkylation catalyst comprising a pore size distribution that sterically constrains formation of the condensed hydrocarbon species on the alkylation catalyst or by synthesizing the alkylation catalyst to comprise a decreased number of strongly acidic active sites is also disclosed, as is a method of improving a regeneration efficiency of the alkylation catalyst.

  19. Outlook for the U.S. alkylation industry

    International Nuclear Information System (INIS)

    Felten, J.R.; Bradshaw, T.; McCarthy, K.

    1994-01-01

    Alkylation has long been recognized in the refining industry as one of the best options to convert refinery olefins into valuable, clean, high octane blending components. In fact, refinery alkylation is a preferred source of blending stocks for reformulated gasoline. However, the hydrofluoric acid (HF) alkylation process and, to a lesser extent, the sulfuric acid (SA) process have come under increasing pressure in the US due to safety and environmental concerns. This paper examines the current outlook for the US alkylation industry including: key trends and driving forces in the industry, the impact of environmental issues on both HF and SA alkylation, US alkylation supply/demand forecast including the outlook for oxygenates, how US refines will respond to the increased demand and restricted supply for alkylates, and the outlook for new solid acid alkylation (SAC) technology

  20. Mechanisms of resistance to alkylating agents

    OpenAIRE

    Damia, G.; D‘Incalci, M.

    1998-01-01

    Alkylating agents are the most widely used anticancer drugs whose main target is the DNA, although how exactly the DNA lesions cause cell death is still not clear. The emergence of resistance to this class of drugs as well as to other antitumor agents is one of the major causes of failure of cancer treatment. This paper reviews some of the best characterized mechanisms of resistance to alkylating agents. Pre- and post-target mechanisms are recognized, the former able to limit the formation of...

  1. Graft copolymerization of a series of alkyl acrylates and alkyl methacrylates onto polyethylene

    International Nuclear Information System (INIS)

    Zurakowska-Orszagh, J.; Soerjosoeharto, K.; Busz, W.; Oldziejewski, J.

    1977-01-01

    Graft copolymerization of a series of alkyl acrylates and alkyl methacrylates into polyethylene of Polish production was investigated, using benzoyl peroxide as the initiator as well as preirradiation technique, namely ionizing radiation from a 60 Co γ-source. The effect of α-carbon methyl substituent of methacrylates as well as the influence of the length of alkyl chains in the ester groups of both series of monomers into the grafting process was observed. The ungrafted and some of the grafted polyethylene film obtained was studied by infrared spectrophotometry. (author)

  2. Examining spatial patterns in polycyclic aromatic compounds measured in stream macroinvertebrates near a small subarctic oil and gas operation.

    Science.gov (United States)

    Korosi, J B; Eickmeyer, D C; Chin, K S; Palmer, M J; Kimpe, L E; Blais, J M

    2016-03-01

    The Cameron River runs through a small, remote petrochemical development in the Cameron Hills (Northwest Territories, Canada). In order to evaluate the exposure of aquatic biota to contaminants from oil and gas activities, we measured polycyclic aromatic compounds (PACs) in macroinvertebrates collected from sites and tributaries along the Cameron River, including upstream and downstream of the development, and sites located near drilled wells (developed). Macroinvertebrate tissue PAC burdens ranged from 0.2-2.8 μg g(-1) lipid for unsubstituted compounds, and from 4.2-63.2 μg g(-1) lipid for alkylated compounds, relatively low compared to similar studies from more industrialized regions in North America. There was no significant difference in tissue PAC burdens between upstream, downstream, or developed sites (p = 0.12), although alkyl PACs in five out of seven developed sites were higher than the regional average. Petrogenic PACs were dominant in most samples, including alkyl fluorines, alkyl phenanthrene/anthracenes, and alkyl dibenzothiophenes. Minimal changes in PAC composition in macroinvertebrate tissues were detected along the Cameron River, with the exception of the two sites furthest downstream that had high concentrations of C3-C4 naphthalene. Overall, our results suggest that oil and gas development in the Cameron Hills has not resulted in substantial increases in PAC bioaccumulation in stream macroinvertebrates, although the potential that alkyl naphthalenes are being transported downstream from the development warrants further attention.

  3. Contorted polycyclic aromatics.

    Science.gov (United States)

    Ball, Melissa; Zhong, Yu; Wu, Ying; Schenck, Christine; Ng, Fay; Steigerwald, Michael; Xiao, Shengxiong; Nuckolls, Colin

    2015-02-17

    CONSPECTUS: This Account describes a body of research in the design, synthesis, and assembly of molecular materials made from strained polycyclic aromatic molecules. The strain in the molecular subunits severely distorts the aromatic molecules away from planarity. We coined the term "contorted aromatics" to describe this class of molecules. Using these molecules, we demonstrate that the curved pi-surfaces are useful as subunits to make self-assembled electronic materials. We have created and continue to study two broad classes of these "contorted aromatics": discs and ribbons. The figure that accompanies this conspectus displays the three-dimensional surfaces of a selection of these "contorted aromatics". The disc-shaped contorted molecules have well-defined conformations that create concave pi-surfaces. When these disc-shaped molecules are substituted with hydrocarbon side chains, they self-assemble into columnar superstructures. Depending on the hydrocarbon substitution, they form either liquid crystalline films or macroscopic cables. In both cases, the columnar structures are photoconductive and form p-type, hole- transporting materials in field effect transistor devices. This columnar motif is robust, allowing us to form monolayers of these columns attached to the surface of dielectrics such as silicon oxide. We use ultrathin point contacts made from individual single-walled carbon nanotubes that are separated by a few nanometers to probe the electronic properties of short stacks of a few contorted discs. We find that these materials have high mobility and can sense electron-deficient aromatic molecules. The concave surfaces of these disc-shaped contorted molecules form ideal receptors for the molecular recognition and assembly with spherical molecules such as fullerenes. These interfaces resemble ball-and-socket joints, where the fullerene nests itself in the concave surface of the contorted disc. The tightness of the binding between the two partners can be

  4. Aromatic molecules as spintronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda, J. H., E-mail: judith.ojeda@uptc.edu.co [Instituto de Alta investigación, Universidad de Tarapacá, Casilla 7D Arica (Chile); Grupo de Física de Materiales, Universidad Pedagógica y Tecnológica de Colombia, Tunja (Colombia); Orellana, P. A. [Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso (Chile); Laroze, D. [Instituto de Alta investigación, Universidad de Tarapacá, Casilla 7D Arica (Chile)

    2014-03-14

    In this paper, we study the spin-dependent electron transport through aromatic molecular chains attached to two semi-infinite leads. We model this system taking into account different geometrical configurations which are all characterized by a tight binding Hamiltonian. Based on the Green's function approach with a Landauer formalism, we find spin-dependent transport in short aromatic molecules by applying external magnetic fields. Additionally, we find that the magnetoresistance of aromatic molecules can reach different values, which are dependent on the variations in the applied magnetic field, length of the molecules, and the interactions between the contacts and the aromatic molecule.

  5. Oxidative Umpolung α‐Alkylation of Ketones

    DEFF Research Database (Denmark)

    Shneider, O. Svetlana; Pisarevsky, Evgeni; Fristrup, Peter

    2015-01-01

    We disclose a hypervalent iodine mediated α-alkylative umpolung reaction of carbonyl compounds with dialkylzinc as the alkyl source. The reaction is applicable to all common classes of ketones including 1,3-dicarbonyl compounds and regular ketones via their lithium enolates. The α-alkylated...

  6. 40 CFR 721.10053 - Alkyl silane methacrylate (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl silane methacrylate (generic... Specific Chemical Substances § 721.10053 Alkyl silane methacrylate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl silane...

  7. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for the...

  8. IONIC LIQUID-CATALYZED ALKYLATION OF ISOBUTANE WITH 2-BUTENE

    Science.gov (United States)

    A detailed study of the alkylation of isobutane with 2-butene in ionic liquid media has been conducted using 1-alkyl-3-methylimidazolium halides?aluminum chloride encompassing various alkyl groups (butyl-, hexyl-, and octyl-) and halides (Cl, Br, and I) on its cations and anions,...

  9. Effects of alkylate fuel on exhaust emissions and secondary aerosol formation of a 2-stroke and a 4-stroke scooter

    Science.gov (United States)

    Zardini, Alessandro A.; Platt, Stephen M.; Clairotte, Michael; El Haddad, Imad; Temime-Roussel, Brice; Marchand, Nicolas; Ježek, Irena; Drinovec, Luka; Močnik, Griša; Slowik, Jay G.; Manfredi, Urbano; Prévôt, André S. H.; Baltensperger, Urs; Astorga, Covadonga

    2014-09-01

    Regulated and unregulated emissions from a 2-stroke and a 4-stroke scooter were characterized during a legislative driving cycle in a certified laboratory. Scooter exhaust was analyzed at the tailpipe, in a dilution tunnel, and partly collected in a mobile smog chamber for photochemical ageing. We present evidence that the photochemically aged exhaust from a 2-stroke and a 4-stroke scooter produces considerable amounts of secondary organic aerosol: from 1.5 to 22.0 mg/km, and from 5.5 to 6.6 mg/km, respectively. Tests were repeated after replacing the standard petrol and synthetic lube oil with an alkylate fuel (with low content of aromatic compounds) and ultra-clean lube oil (low ash forming potential). We observed emission reduction (with some exceptions) for several gaseous and particulate phase species, in particular for carbon monoxide (from 8% up to 38% and from 31% to 50%, for the 2-stroke and the 4-stroke scooters, respectively), particulate mass (from 32% up to 75% for the 2-stroke scooter), aromatic compounds (89% and 97% for the 2-stroke and the 4-stroke scooter, respectively), and secondary organic aerosol (from 87% to 100% and 99% for the 2-stroke and the 4-stroke scooters, respectively). We attribute the organic aerosol reduction to the low content of aromatics in the alkylate fuel.

  10. Quantitative estimation of the extent of alkylation of DNA following treatment of mammalian cells with non-radioactive alkylating agents

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, R.D. (Univ. of Tennessee, Oak Ridge); Regan, J.D.

    1981-01-01

    Alkaline sucrose sedimentation has been used to quantitate phosphotriester formation following treatment of human cells with the monofunctional alkylating agents methyl and ethyl methanesulfonate. These persistent alkaline-labile lesions are not repaired during short-term culture conditions and thus serve as a useful and precise index of the total alkylation of the DNA.Estimates of alkylation by this procedure compare favorably with direct estimates by use of labeled alkylating agents.

  11. Williamson alkylation approach to the synthesis of poly(alkyl vinyl ether) copolymers

    International Nuclear Information System (INIS)

    Markova, D.; Christova, D.; Velichkova, R.

    2008-01-01

    A method for synthesis of poly(alkyl vinyl ether-co-vinyl alcohol) copolymers was developed based on the Williamson's alkylation of poly(vinyl acetate) (PVAc) with alkyl iodides. The influence of the alkylating agent and the reaction conditions on the efficiency of the modification reaction was investigated. The copolymers obtained were characterized by means of 1 H NMR and GPC. It was proved that by applying the proposed method copolymers of different composition and properties containing methyl vinyl ether, ethyl vinyl ether as well as n-butyl vinyl ether units could be prepared. Poly(methyl vinyl ether-co-vinyl alcohol)s of high degree of methylation exhibit sharp temperature response at 38-39 deg C in aqueous solution typical of the so-called smart polymers. (authors)

  12. Spurious cooperativity in alkylated succinic acids

    Science.gov (United States)

    Ben-Naim, A.

    1998-03-01

    The proton-proton correlation, as measured by the ratio between the second and the first dissociation constants of dibasic acid, is sometimes very large and far beyond what could be explained by electrostatic theories. We propose a novel interpretation of this phenomenon based on the idea of spurious cooperativity. The general theoretical framework underlying the onset of spurious cooperativity is developed first. The basic result is that whenever a binding (or dissociating) two-site (or more) system splits into a mixture of noninterconverting isomers the binding isotherm (or the titration curve) behaves as if it is more negatively cooperative compared with the genuine cooperativities of the individual isomer. The theory is applied to a specific system of α-α' dialkyl succinic acid. It is known that the Meso form of these alkylated derivatives show a normal correlation of the same order of magnitude as in succinic acid. On the other hand, the Racemic form of these alkylated derivatives shows anomalous strong negative correlations when the alkyl groups become large (e.g., isopropyl and tert butyl). It is shown that the theory of spurious cooperativity can explain the different behavior of the Racemic and the Meso forms, as well as the onset of anomalous strong negative correlations when the alkyl groups become large.

  13. Biodesulfurization of dibenzothiophene and its alkylated derivatives ...

    African Journals Online (AJOL)

    RIPI-S81 is a new dibenzothiophene (DBT)-desulfurizing bacterium, which was isolated by Research Institute of Petroleum Industry in Iran. Resting cells and growing cells of RIPI-S81 was able to convert alkylated dibenzothiophenes (Cx DBTs) to hydroxybiphenyls such that they were almost stoichiometrically accumulated ...

  14. Poly(ethyleneoxide) functionalization through alkylation

    Science.gov (United States)

    Sivanandan, Kulandaivelu; Eitouni, Hany Basam; Li, Yan; Pratt, Russell Clayton

    2015-04-21

    A new and efficient method of functionalizing high molecular weight polymers through alkylation using a metal amide base is described. This novel procedure can also be used to synthesize polymer-based macro-initiators containing radical initiating groups at the chain-ends for synthesis of block copolymers.

  15. Catalytic Asymmetric Alkylation of Aryl Heteroaryl Ketones

    NARCIS (Netherlands)

    Ortiz, Pablo; Harutyunyan, Syuzanna; del Hoyo, Ana

    Tertiary diarylmethanols are highly bioactive structural motifs. A new strategy to access chiral tertiary diarylmethanols through copper-catalyzed direct alkylation of (di)(hetero)aryl ketones by using Grignard reagents was developed. The low reactivity and the similarity of the enantiotopic faces

  16. Palladium Catalyzed Allylic C-H Alkylation

    DEFF Research Database (Denmark)

    Engelin, Casper Junker; Fristrup, Peter

    2011-01-01

    an acetate ion coordinated to Pd. Several of the reported systems rely on benzoquinone for re-oxidation of the active catalyst. The scope for nucleophilic addition in allylic C-H alkylation is currently limited, due to demands on pKa of the nucleophile. This limitation could be due to the pH dependence...

  17. Palladium catalysed asymmetric alkylation of benzophenone Schiff ...

    Indian Academy of Sciences (India)

    Asymmetric alkyl substitution of various benzophenone Schiff base substrates under biphasic conditions proceeded using optically active Palladium(II) complexes. The corresponding products were obtained in high yields but with moderate enantiomeric excess (ee). Addition of specific ionic liquids to the reaction medium ...

  18. Palladium catalysed asymmetric alkylation of benzophenone Schiff ...

    Indian Academy of Sciences (India)

    transfer catalysts for asym- metric alkylation of achiral Schiff base esters. Trans. Met. Chem. 35 249. (doi:10.1007/s11243-010-9416-4). 29. Wilkes J S 2002 A short history of ionic liquids from molten salts to neoteric solvents. Green Chem. 4 73. 30.

  19. Recent developments in isobutane/olefin alkylation

    Energy Technology Data Exchange (ETDEWEB)

    Lercher, J.A.; Feller, A. [Inst. fuer Technische Chemie, Technische Univ. Muenchen (Germany)

    2002-07-01

    The isobutane/alkene alkylation is reviewed with respect to recent process developments based on liquid and solid acid catalysts. A brief overview about the established processes is given followed by the description of new processes based on solid acids under development. (orig.)

  20. Mechanisms of action of quinone-containing alkylating agents: DNA alkylation by aziridinylquinones.

    Science.gov (United States)

    Hargreaves, R H; Hartley, J A; Butler, J

    2000-11-01

    Aziridinyl quinones can be activated by cellular reductases eg. DT-diaphorase and cytochrome P450 reductase to form highly reactive DNA alkylating agents. The mechanisms by which this activation and alkylation take place are many and varied. Using clinically relevant and experimental agents this review will describe many of these mechanisms. The agents discussed are Mitomycin C, EO9 and analogues, diaziridinylbenzoquinones and the pyrrolo[1, 2-alpha]benzimidazolequinones.

  1. Bis(trialkylsilyl) peroxides as alkylating agents in the copper-catalyzed selective mono-N-alkylation of primary amides.

    Science.gov (United States)

    Sakamoto, Ryu; Sakurai, Shunya; Maruoka, Keiji

    2017-06-13

    The copper-catalyzed selective mono-N-alkylation of primary amides with bis(trialkylsilyl) peroxides as alkylating agents was reported. The results of a mechanistic study suggest that this reaction should proceed via a free radical process that includes the generation of alkyl radicals from bis(trialkylsilyl) peroxides.

  2. Embryotoxicity induced by alkylating agents. Some methodological aspects of DNA alkylation studies in murine embryos using ethylmethanesulfonate.

    Science.gov (United States)

    Platzek, T; Bochert, G; Rahm, U; Neubert, D

    1987-05-01

    Synthesis and spectroscopic analysis of some alkylated DNA purine bases are described. HPLC separation methods are developed for the determination of DNA alkylation rates in mammalian embryonic tissues. Following treatment of pregnant mice with the ethylating agent ethylmethanesulfonate (EMS), an appreciable amount of alkylation (ethylation and methylation) was found in the nuclear DNA of the embryos during organogenesis. The results are discussed in context of our thesis that a certain amount of DNA alkylation in the embryos is correlated to the teratogenic potential of alkylating agents.

  3. Reaction of lithium diethylamide with an alkyl bromide and alkyl benzenesulfonate: origins of alkylation, elimination, and sulfonation.

    Science.gov (United States)

    Gupta, Lekha; Ramírez, Antonio; Collum, David B

    2010-12-17

    A combination of NMR, kinetic, and computational methods are used to examine reactions of lithium diethylamide in tetrahydrofuran (THF) with n-dodecyl bromide and n-octyl benzenesulfonate. The alkyl bromide undergoes competitive S(N)2 substitution and E2 elimination in proportions independent of all concentrations except for a minor medium effect. Rate studies show that both reactions occur via trisolvated-monomer-based transition structures. The alkyl benzenesulfonate undergoes competitive S(N)2 substitution (minor) and N-sulfonation (major) with N-sulfonation promoted at low THF concentrations. The S(N)2 substitution is shown to proceed via a disolvated monomer suggested computationally to involve a cyclic transition structure. The dominant N-sulfonation follows a disolvated-dimer-based transition structure suggested computationally to be a bicyclo[3.1.1] form. The differing THF and lithium diethylamide orders for the two reactions explain the observed concentration-dependent chemoselectivities.

  4. Selective production of xylenes from alkyl-aromatics and heavy reformates over dual-zeolite catalyst

    Czech Academy of Sciences Publication Activity Database

    Ali, S. A.; Aitani, A.; Čejka, Jiří; Al-Khattaf, S.

    2015-01-01

    Roč. 243, APR 2015 (2015), s. 118-127 ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : transalkylation * mordenite * xylenes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.312, year: 2015

  5. Radiolytic crosslinking and chain scission in aliphatic and alkyl-aromatic polyamides: Pt. 2

    International Nuclear Information System (INIS)

    Lyons, B.J.; Glover, L.C. Jr.

    1991-01-01

    Regression analysis of the radiation parameters of nine aliphatic polyamides exposed to ionizing radiation leads to the conclusion that the decline in the ratio of chain scission to crosslinking in higher aliphatic polyamides is best related to the linear increase in the methylene content of, or the number of methylene groups in, the polyamide repeat unit. G(crosslink)[G(X)] and G(chain scission) [G(CS)] values, however, do not correlate well with either of these parameters. Rather it is found that the major determinant of yields [about 80-85% of the variation for G(X), 70% for G(CS)] is the number of hydrogen atoms or methylene groups in the amine residue. Although, logically, the yields of crosslinks and chain scissions in polyamides would be expected to tend to that of polyethylene as the number of methylene groups in the repeat unit increases, use of two models assuming an exponential trend to the G(X) value characteristic of polyethylene in the analysis did not provide better fits to the data than the simple linear model referred to above. Indeed, the assumption of a significant exponential trend factor led to a marked drop in the goodness of fit. (author)

  6. Summertime C1-C5 alkyl nitrates over Beijing, northern China: Spatial distribution, regional transport, and formation mechanisms

    Science.gov (United States)

    Sun, Jingjing; Li, Zeyuan; Xue, Likun; Wang, Tao; Wang, Xinfeng; Gao, Jian; Nie, Wei; Simpson, Isobel J.; Gao, Rui; Blake, Donald R.; Chai, Fahe; Wang, Wenxing

    2018-05-01

    Alkyl nitrates (RONO2) are an important class of nitrogen oxides reservoirs in the atmosphere and play a key role in tropospheric photochemistry. Despite the increasing concern for photochemical air pollution over China, the knowledge of characteristics and formation mechanisms of alkyl nitrates in this region is limited. We analyzed C1-C5 alkyl nitrates measured in Beijing at a polluted urban site in summer 2008 and at a downwind rural site in summers of both 2005 and 2008. Although the abundances of NOx and hydrocarbons were much lower at the rural site, the mixing ratios of RONO2 were comparable between both sites, emphasizing the regional nature of alkyl nitrate pollution. Regional transport of urban plumes governed the elevated RONO2 levels at the rural site. The concentrations of C1-C2 RONO2 were significantly higher at the rural site in 2008 compared to 2005 despite a decline in NOx and anthropogenic VOCs, mainly owing to enhanced contributions from biogenic VOCs. The photochemical formation regimes of RONO2 were evaluated by both a simplified sequential reaction model and a detailed master chemical mechanism box model. The observed C4-C5 RONO2 levels can be well explained by the photochemical degradation of n-butane and n-pentane, while the sources of C1-C3 RONO2 were rather complex. In addition to the C1-C3 alkanes, biogenic VOCs and reactive aromatics were also important precursors of methyl nitrate, and alkenes and long-chain alkanes contributed to the formation of C2-C3 RONO2. This study provides insights into the spatial distribution, inter-annual variation and photochemical formation mechanisms of alkyl nitrate pollution over the Beijing area.

  7. Geochemical markers and polycyclic aromatic hydrocarbons in solvent extracts from diesel engine particulate matter.

    Science.gov (United States)

    Fabiańska, Monika; Kozielska, Barbara; Bielaczyc, Piotr; Woodburn, Joseph; Konieczyński, Jan

    2016-04-01

    Exhaust particulate from compression ignition (CI) engines running on engine and chassis dynamometers was studied. Particulate dichloromethane extracts were qualitatively and quantitatively analyzed for polycyclic aromatic hydrocarbons (PAHs) and biomarkers by gas chromatography with flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). PAH group profiles were made and the PAH group shares according to the number of rings (2 or 3; 4; 5 or more) as well as diagnostic indices were calculated. Values of geochemical ratios of selected biomarkers and alkyl aromatic hydrocarbons were compared with literature values. A geochemical interpretation was carried out using these values and biomarker and alkyl aromatic hydrocarbon distributions. It has been shown that geochemical features are unequivocally connected to the emission of fossil fuels and biofuels burned in CI engines. The effect of the exothermic combustion process is limited to low-molecular-weight compounds, which shows that the applied methodology permits source identification of PAHs coexisting in the particulate emitted.

  8. Reaction engineering of urea alcoholysis: Alkyl carbamates

    OpenAIRE

    Mote, Dhananjay R.; Ranade, Vivek V.

    2017-01-01

    Urea alcoholysis is a reversible reaction generating alkyl carbamate and ammonia as products. The reaction can be performed non-catalytically or in presence of catalyst. The first step in Reaction engineering analysis is to finalize the reactor configuration. In this case it is important to determine the necessity of reactive separation (simultaneous reaction and separation). This has been addressed by first establishing the reversibility of the reaction through theoretical and experimental i...

  9. ALKYL PYROPHOSPHATE METAL SOLVENT EXTRACTANTS AND PROCESS

    Science.gov (United States)

    Long, R.L.

    1958-09-30

    A process is presented for the recovery of uranium from aqueous mineral acidic solutions by solvent extraction. The extractant is a synmmetrical dialkyl pyrophosphate in which the alkyl substituents have a chain length of from 4 to 17 carbon atoms. Mentioned as a preferred extractant is dioctyl pyrophosphate. The uranium is precipitated irom the organic extractant phase with an agent such as HF, fluoride salts. alcohol, or ammonia.

  10. Advances towards aromatic oligoamide foldamers

    DEFF Research Database (Denmark)

    Hjelmgaard, Thomas; Plesner, Malene; Dissing, Mette Marie

    2014-01-01

    We have efficiently synthesized 36 arylopeptoid dimers with ortho-, meta-, and para-substituted aromatic backbones and tert-butyl or phenyl side chains. The dimers were synthesized by using a "submonomer method" on solid phase, by applying a simplified common set of reaction conditions. X-ray...... of the surrounding aromatic backbone. Investigation of the X-ray structures of two arylopeptoid dimers disclosed that the tert-butyl side chain invokes a cis amide conformation with a closely packed structure of the surrounding aromatic backbone while the phenyl side chain results in a trans amide conformation...

  11. Novel Profluorescent Nitroxides for Monitoring Alkyl Radical Reactions During Radiation Degradation

    International Nuclear Information System (INIS)

    George, G.

    2006-01-01

    Hindered amine stabilizers (HAS) are effective at retarding the photo-oxidative and high energy radiation degradation of PP and in certain circumstances, also thermo-oxidative degradation. The effectiveness of HAS as retarders of oxidation relies on the oxidation of the N-C bond by polymer hydroperoxide, ROOH, to form the nitroxyl group -NO which is the scavenger of polymer alkyl radicals, R. This reaction, which produces the alkoxy amine: -NO-R, must be competitive with the reaction of R with oxygen (which gives the chain-carrying peroxy radical, RO 2 ) if this stabilization mechanism is to be important in the inhibition of radiation-induced oxidative degradation of polyolefins by HAS. The rate of this reaction is high and in solution the rate coefficient is from 1 to 9x10 8 l mol - 1 s - 1. The efficient radical trapping by nitroxides has been widely employed in spin-trapping studies by electron spin resonance (esr) spectroscopy]. In addition to the hindered piperidine structure of commercial HAS, more rigid aromatic systems have been studied that are more stable to oxidative degradation and are more efficient at scavenging alkyl radicals. One such family is the iso-indoline nitroxide system, TMDBIO, shown below which, as it contains the phenanthrene fluorophore, is termed phenanthrene nitroxide. This nitroxide only becomes fluorescent when it reacts with alkyl radicals or is reduced and is termed profluorescent. TMDBIO has a vanishingly small fluorescence quantum yield (φ∼10 - 4) due to the enhanced intersystem crossing from the first excited singlet state to the ground state due to electron exchange interactions of the nitroxyl radical. When the nitroxide traps an alkyl radical, R, the resulting alkoxy amine is fluorescent (φ∼10 - 1) and the emission intensity is a measure of the number of reactions that have occurred. This property may be exploited by using quantitative fluorescence spectroscopy to follow the reaction of the nitroxide with alkyl radicals

  12. Distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in street dust from the Tokyo Metropolitan area.

    Science.gov (United States)

    Takada, H; Onda, T; Harada, M; Ogura, N

    1991-09-01

    Molecular distributions of polycyclic aromatic hydrocarbons (PAHs) in street dust samples collected from the Tokyo Metropolitan area were determined by capillary gas chromatography following HPLC fractionation. Three- to six-ring PAHs and sulfur-heterocyclics were detected. PAHs in the dusts were dominated by three and four unsubstituted ring systems with significant amounts of their alkyl homologues. PAHs were widely distributed in the streets, with concentrations (sigma COMB) of a few microgram/g dust. Automobile exhaust, asphalt, gasoline fuel, diesel fuel, tyre particles, automobile crankcase oils, and atmospheric fallout were also analysed. The PAH profile, especially the relative abundance of alkyl-PAHs and sulfur-containing heterocyclics, indicated that PAHs in the street dusts from roads carrying heavy traffic are mainly derived from automobile exhausts; dusts from residential areas have a more significant contribution from atmospheric fallout.

  13. Distribution and origin sources of Polycyclic Aromatic Hydrocarbons (PAHs) pollution in sediment of Sarawak coastal area

    International Nuclear Information System (INIS)

    Mohd Shuhaimi Elias; Abdul Khalik Wood; Zaleha Hashim; Mohd Suhaimi Hamzah; Shamsiah Abdul Rahman; Nazaratul Ashifa Abdullah Salim

    2010-01-01

    Alkyl and parent Polycyclic Aromatic Hydrocarbons (PAHs) compounds in marine sediment sample collected from ten locations along Sarawak coastal areas were extracted and analyzed by using gas chromatography-mass spectrometry. The source identification of PAH pollution in marine sediment of Sarawak coastal areas were identify by ratios technique of An/ An+phen, Fl/ Fl +Py, B[a]A/ (B[a]A+Chry) and total Methyl Phen/ Phen. The total alkyl and parent PAHs concentration varies from 36.5 - 277.4 ng/ g dry weight (d.w.) with a mean concentration of 138.2 ng/ g d.w. The ratio values of PAHs pollution in marine sediment of Sarawak coastal areas are clearly indicating the PAHs pollutions are originated from petroleum (petrogenic) and petroleum combustion (pyrolytic). However, the origin sources of PAHs pollution in a few stations were uncertain due to mixing sources of PAHs. (author)

  14. DNA-directed alkylating ligands as potential antitumor agents: sequence specificity of alkylation by intercalating aniline mustards.

    Science.gov (United States)

    Prakash, A S; Denny, W A; Gourdie, T A; Valu, K K; Woodgate, P D; Wakelin, L P

    1990-10-23

    The sequence preferences for alkylation of a series of novel parasubstituted aniline mustards linked to the DNA-intercalating chromophore 9-aminoacridine by an alkyl chain of variable length were studied by using procedures analogous to Maxam-Gilbert reactions. The compounds alkylate DNA at both guanine and adenine sites. For mustards linked to the acridine by a short alkyl chain through a para O- or S-link group, 5'-GT sequences are the most preferred sites at which N7-guanine alkylation occurs. For analogues with longer chain lengths, the preference of 5'-GT sequences diminishes in favor of N7-adenine alkylation at the complementary 5'-AC sequence. Magnesium ions are shown to selectively inhibit alkylation at the N7 of adenine (in the major groove) by these compounds but not the alkylation at the N3 of adenine (in the minor groove) by the antitumor antibiotic CC-1065. Effects of chromophore variation were also studied by using aniline mustards linked to quinazoline and sterically hindered tert-butyl-9-aminoacridine chromophores. The results demonstrate that in this series of DNA-directed mustards the noncovalent interactions of the carrier chromophores with DNA significantly modify the sequence selectivity of alkylation by the mustard. Relationships between the DNA alkylation patterns of these compounds and their biological activities are discussed.

  15. Distribution of methyl and ethyl adducts following alkylation with monofunctional alkylating agents.

    Science.gov (United States)

    Beranek, D T

    1990-07-01

    Alkylating agents, because of their ability to react directly with DNA either in vitro or in vivo, or following metabolic activation as in the case of the dialkylnitrosamines, have been used extensively in studying the mechanisms of mutagenicity and carcinogenicity. Their occurrence is widespread in the environment and human exposure from natural and pollutant sources is universal. Since most of these chemicals show varying degrees of both carcinogenicity and mutagenicity, and exhibit compound-specific binding patterns, they provide an excellent model for studying molecular dosimetry. Molecular dosimetry defines dose as the number of adducts bound per macromolecule and relates the binding of these adducts to the human mutagenic or carcinogenic response. This review complies DNA alkylation data for both methylating and ethylating agents in a variety of systems and discusses the role these alkylation products plays in molecular mutagenesis.

  16. Manganese-catalyzed Dehydrogenative Alkylation or α-Olefination of Alkyl-N-Heteroaromatics by Alcohols.

    Science.gov (United States)

    Kempe, Rhett; Zhang, Guoying; Irrgang, Torsten; Dietel, Thomas; Kallmeier, Fabian

    2018-05-02

    Catalysis involving earth-abundant transition metals is an option to help save our rare noble metal resources and is especially interesting if novel reactivity or selectivity patterns are observed. We report here on a novel reaction: the dehydrogenative alkylation or α-olefination of alkyl-N-heteroaromatics by alcohols. Manganese complexes developed in our laboratory catalyze the reaction efficiently. Fe and Co complexes stabilized by such ligands are essentially inactive. Hydrogen is liberated during the reaction and bromo or iodo functional groups and olefins can be tolerated. A variety of alkyl-N-heteroaromatics can be functionalized, and benzyl and aliphatic alcohols undergo the reaction. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Description of aromaticity in porphyrinoids.

    Science.gov (United States)

    Wu, Judy I; Fernández, Israel; Schleyer, Paul v R

    2013-01-09

    Like the larger nonplanar Möbius rings, porphyrinoid aromaticity is not due primarily to the macrocyclic π conjugation of the corresponding annulene perimeters. The block-localized wave function (BLW)-derived aromatic stabilization energies (ASE) of several porphyrinoids reveal that, on a per atom basis, the appended 6π electron heterocycles of porphyrinoids confer aromaticity much more effectively than the macrocyclic 4n+2 π electron conjugations. There is no direct relationship between thermochemical stability of porphyrinoids and their macrocyclic 4n or 4n+2 π electron counts. Porphyrinoids having an "antiaromatic" macrocyclic 4n+2 π electron conjugation pathway (e.g., 4) as well as those having no macrocyclic conjugation (e.g., 9) can be stabilized by aromaticity. Computed nucleus independent chemical shifts (NICS) and the anisotropy of the induced current density (ACID) disclose the intricate local versus macrocyclic circulation interplay for several porphyrinoids.

  18. Visible light- and radiation-induced alkylation of pyridine ring with alkanoic acid

    International Nuclear Information System (INIS)

    Sugimori, Akira; Yamada, Tetsuo

    1986-01-01

    Quinoline and 4-methylquinoline are efficiently alkylated with alkanoic acid in the presence of iron(III) sulfate upon visible light-irradiation. Iron(III) sulfate not only accelerates the photoreaction but also increases the yield of alkylation. Gamma-irradiation also brings about the alkylation. In the photo- and radiation-induced alkylation with alkanoic acid, alkyl radicals play important roles. (author)

  19. Alkylation damage by lipid electrophiles targets functional protein systems.

    Science.gov (United States)

    Codreanu, Simona G; Ullery, Jody C; Zhu, Jing; Tallman, Keri A; Beavers, William N; Porter, Ned A; Marnett, Lawrence J; Zhang, Bing; Liebler, Daniel C

    2014-03-01

    Protein alkylation by reactive electrophiles contributes to chemical toxicities and oxidative stress, but the functional impact of alkylation damage across proteomes is poorly understood. We used Click chemistry and shotgun proteomics to profile the accumulation of proteome damage in human cells treated with lipid electrophile probes. Protein target profiles revealed three damage susceptibility classes, as well as proteins that were highly resistant to alkylation. Damage occurred selectively across functional protein interaction networks, with the most highly alkylation-susceptible proteins mapping to networks involved in cytoskeletal regulation. Proteins with lower damage susceptibility mapped to networks involved in protein synthesis and turnover and were alkylated only at electrophile concentrations that caused significant toxicity. Hierarchical susceptibility of proteome systems to alkylation may allow cells to survive sublethal damage while protecting critical cell functions.

  20. Alkylation Damage by Lipid Electrophiles Targets Functional Protein Systems*

    Science.gov (United States)

    Codreanu, Simona G.; Ullery, Jody C.; Zhu, Jing; Tallman, Keri A.; Beavers, William N.; Porter, Ned A.; Marnett, Lawrence J.; Zhang, Bing; Liebler, Daniel C.

    2014-01-01

    Protein alkylation by reactive electrophiles contributes to chemical toxicities and oxidative stress, but the functional impact of alkylation damage across proteomes is poorly understood. We used Click chemistry and shotgun proteomics to profile the accumulation of proteome damage in human cells treated with lipid electrophile probes. Protein target profiles revealed three damage susceptibility classes, as well as proteins that were highly resistant to alkylation. Damage occurred selectively across functional protein interaction networks, with the most highly alkylation-susceptible proteins mapping to networks involved in cytoskeletal regulation. Proteins with lower damage susceptibility mapped to networks involved in protein synthesis and turnover and were alkylated only at electrophile concentrations that caused significant toxicity. Hierarchical susceptibility of proteome systems to alkylation may allow cells to survive sublethal damage while protecting critical cell functions. PMID:24429493

  1. Effects of alkyl parabens on plant pathogenic fungi.

    Science.gov (United States)

    Ito, Shinsaku; Yazawa, Satoru; Nakagawa, Yasutaka; Sasaki, Yasuyuki; Yajima, Shunsuke

    2015-04-15

    Alkyl parabens are used as antimicrobial preservatives in cosmetics, food, and pharmaceutical products. However, the mode of action of these chemicals has not been assessed thoroughly. In this study, we determined the effects of alkyl parabens on plant pathogenic fungi. All the fungi tested, were susceptible to parabens. The effect of linear alkyl parabens on plant pathogenic fungi was related to the length of the alkyl chain. In addition, the antifungal activity was correlated with the paraben-induced inhibition of oxygen consumption. The antifungal activity of linear alkyl parabens likely originates, at least in part, from their ability to inhibit the membrane respiratory chain, especially mitochondrial complex II. Additionally, we determined that some alkyl parabens inhibit Alternaria brassicicola infection of cabbage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Efficient and selective N-alkylation of amines with alcohols catalysed by manganese pincer complexes

    Science.gov (United States)

    Elangovan, Saravanakumar; Neumann, Jacob; Sortais, Jean-Baptiste; Junge, Kathrin; Darcel, Christophe; Beller, Matthias

    2016-01-01

    Borrowing hydrogen (or hydrogen autotransfer) reactions represent straightforward and sustainable C–N bond-forming processes. In general, precious metal-based catalysts are employed for this effective transformation. In recent years, the use of earth abundant and cheap non-noble metal catalysts for this process attracted considerable attention in the scientific community. Here we show that the selective N-alkylation of amines with alcohols can be catalysed by defined PNP manganese pincer complexes. A variety of substituted anilines are monoalkylated with different (hetero)aromatic and aliphatic alcohols even in the presence of other sensitive reducible functional groups. As a special highlight, we report the chemoselective monomethylation of primary amines using methanol under mild conditions. PMID:27708259

  3. Efficient and selective N-alkylation of amines with alcohols catalysed by manganese pincer complexes

    Science.gov (United States)

    Elangovan, Saravanakumar; Neumann, Jacob; Sortais, Jean-Baptiste; Junge, Kathrin; Darcel, Christophe; Beller, Matthias

    2016-10-01

    Borrowing hydrogen (or hydrogen autotransfer) reactions represent straightforward and sustainable C-N bond-forming processes. In general, precious metal-based catalysts are employed for this effective transformation. In recent years, the use of earth abundant and cheap non-noble metal catalysts for this process attracted considerable attention in the scientific community. Here we show that the selective N-alkylation of amines with alcohols can be catalysed by defined PNP manganese pincer complexes. A variety of substituted anilines are monoalkylated with different (hetero)aromatic and aliphatic alcohols even in the presence of other sensitive reducible functional groups. As a special highlight, we report the chemoselective monomethylation of primary amines using methanol under mild conditions.

  4. Bioassay of polycyclic aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Van Kirk, E.A.

    1980-08-01

    A positive relationship was found between the photodynamic activity of 24 polycyclic aromatic hydrocarbons versus published results on the mutagenicity, carcinogenicity, and initiation of unscheduled DNA synthesis. Metabolic activation of benzo(a)pyrene resulted in detection of increased mutagenesis in Paramecium tetraurelia as found also in the Ames Salmonella assay. The utility of P. tetraurelia as a biological detector of hazardous polycyclic aromatic hydrocarbons is discussed.

  5. Biosynthesis of bacterial aromatic polyketides.

    Science.gov (United States)

    Zhan, Jixun

    2009-01-01

    Aromatic polyketides represent important members of the family of polyketides, which have displayed a wide assortment of bioactive properties, such as antibacterial, antitumor, and antiviral activities. Bacterial aromatic polyketides are mainly synthesized by type II polyketide synthases (PKSs). Whereas malonyl-CoA is exclusively used as the extender unit, starter units can vary in different aromatic polyketide biosynthetic pathways, leading to a variety of polyketide backbones. Once the polyketide chains are elongated by the minimal PKSs to the full length, the immediate tailoring enzymes including ketoreductases, oxygenases and cyclases will work on the nascent chains to form aromatic structures, which will be further decorated by those late tailoring enzymes such as methyltransferases and glycosyltransferases. The mechanistic studies on the biosynthetic pathways of aromatic polyketides such as oxytetracycline and pradimicin A have been extensively carried out in recent years. Engineered biosynthesis of novel "unnatural" polyketides has been achieved in heterologous hosts such as Streptomyces coelicolor and Escherichia coli. This review covers the most recent advances in aromatic polyketide biosynthesis, which provide new enzymes or methods for building novel polyketide biosynthetic machinery.

  6. Copper-catalyzed radical carbooxygenation: alkylation and alkoxylation of styrenes.

    Science.gov (United States)

    Liao, Zhixiong; Yi, Hong; Li, Zheng; Fan, Chao; Zhang, Xu; Liu, Jie; Deng, Zixin; Lei, Aiwen

    2015-01-01

    A simple copper-catalyzed direct radical carbooxygenation of styrenes is developed utilizing alkyl bromides as radical resources. This catalytic radical difunctionalization accomplishes both alkylation and alkoxylation of styrenes in one pot. A broad range of styrenes and alcohols are well tolerated in this transformation. The EPR experiment shows that alkyl halides could oxidize Cu(I) to Cu(II) in this transformation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Toward Efficient Palladium-Catalyzed Allylic C-H Alkylation

    DEFF Research Database (Denmark)

    Jensen, Thomas; Fristrup, Peter

    2009-01-01

    Recent breakthroughs have proved that direct palladium (II)-catalyzed allylic C-H alkylation can be achieved. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalyzed allylic alkylation can be lifted. These initial reports hold great promise...... for the development of allylic C-H alkylation into a widely applicable methodology, thus providing a means to enhance synthetic efficiency in these reactions....

  8. Possible targets for the aneugenic activity of alkylating agents

    Energy Technology Data Exchange (ETDEWEB)

    Pellerano, P. [IST-National Institute for Research on Cancer, Genova (Italy); Abbondandolo, A. [Univ. of Genova (Italy); Bonatti, S.; Simili, M. [CNR Institute of Mutagenesis and Differentiation, Pisa (Italy)

    1993-12-31

    Alkylating agents have been of invaluable help in mutation research for half a century. In all tested organisms, they have proved able to induce a large variety of genetic effects, including aneuploidy. Credible molecular models exist to explain the ability of alkylating agents to induce gene mutation and to act as initiators in carcinogenesis as a consequence of DNA alkylation at specific sites. On the contrary, neither the mechanism of aneuploidy induction nor the relevant cellular targets are known.

  9. Microbial metabolism of alkyl and condensed thiophenes: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Fedorak, P.M.

    1992-01-01

    This study was conducted to gain a better understanding of the metabolic pathways used by aerobic microorganisms for the biodegradation or biotransformation of organosulfur compounds found in petroleum. The study used alkyl-substituted thiophenes, benzothiophene and alkyl-substituted benzothiophenes and alkyl-substituted dibenzothiophenes. The results provide information relevant to environmental matters, aspects of microbial transformations in petroleum reservoirs and further assessment of the feasibility of biodesulfurization.

  10. Development of novel alkylating drugs as anticancer agents.

    Science.gov (United States)

    Izbicka, Elzbieta; Tolcher, Anthony W

    2004-06-01

    Although conventional alkylating drugs have proven efficacy in the treatment of malignancies, the agents themselves are not selective. Therefore, non-specific alkylation of cellular nucleophilic targets may contribute to many of the observed toxic effects. Novel approaches to drug discovery have resulted in candidate agents that are focused on 'soft alkylation'--alkylators with greater target selectivity. This review highlights the discovery of small molecule drugs that bind to DNA with higher selectivity, act in a unique hypoxic tumor environment, or covalently bind specific protein targets overexpressed in cancer, such as topoisomerase II, glutathione transferase pi1, beta-tubulin and histone deacetylase.

  11. Biosynthesis of Alkyl Lysophosphatidic Acid by Diacylglycerol Kinases

    Science.gov (United States)

    Gellett, Amanda M.; Kharel, Yugesh; Sunkara, Manjula; Morris, Andrew J.; Lynch, Kevin R.

    2012-01-01

    Lysophosphatidic acid (LPA) designates a family of bioactive phosphoglycerides that differ in the length and degree of saturation of their radyl chain. Additional diversity is provided by the linkage of the radyl chain to glycerol: acyl, alkyl, or alk-1-enyl. Acyl-LPAs are the predominate species in tissues and biological fluids. Alkyl-LPAs exhibit distinct pharmacodynamics at LPA receptors, potently drive platelet aggregation, and contribute to ovarian cancer aggressiveness. Multiple biosynthetic pathways exist for alkyl-LPA production. Herein we report that diacylglycerol kinases (DGKs) contribute to cell-associated alkyl-LPA production involving phosphorylation of 1-alkyl-2-acetyl glycerol and document the biosynthesis of alkyl-LPA by DGKs in SKOV-3 ovarian cancer cells, specifically identifying the contribution of DGKα. Concurrently, we discovered that treating SKOV-3 ovarian cancer cell with a sphingosine analog stimulates conversion of exogenous 1-alkyl-2-acetyl glycerol to alkyl-LPA, indicating that DGKα contributes significantly to the production of alkyl-LPA in SKOV-3 cells and identifying cross-talk between the sphingolipid and glycerol lipid pathways. PMID:22627129

  12. The antimalarial drug artemisinin alkylates heme in infected mice

    Science.gov (United States)

    Robert, Anne; Benoit-Vical, Françoise; Claparols, Catherine; Meunier, Bernard

    2005-01-01

    Heme alkylation by the antimalarial drug artemisinin is reported in vivo, within infected mice that have been treated at pharmacologically relevant doses. Adducts resulting from the alkylation of heme by the drug were characterized in the spleen of treated mice, and their glucuroconjugated derivatives were present in the urine. Because these heme-artemisinin adducts were not observed in noninfected mice, this report confirms that the alkylating activity of this antimalarial drug is related to the presence of the parasite in infected animals. The identification of heme-artemisinin adducts in mice should be considered as the signature of the alkylation capacity of artemisinin in vivo. PMID:16155128

  13. Determination of reaction rate constants for alkylation of 4-(p-nitrobenzyl) pyridine by different alkylating agents.

    Science.gov (United States)

    Walles, S A

    1980-02-01

    The rate constants have been determined for the reaction between some different alkylating agents and 4-(p-nitrobenzyl) pyridine (NBP) in methanol. These constants have been compared with those for alkylation of aniline in water. All the constants were lower in methanol than in water but in different degrees. The rate constants of the different alkylating agents have been calculated at a nucleophilic strength n=2. The genetic risk defined as the degree of alkylation of a nucleophile (n=2) is equivalent to the rate constant kn=2 and the target dose. The dependence of the genetic risk on the rate constant (kn=2) is discussed.

  14. Thermogravimetric studies on alkyl methacrylate polymers and poly(alkyl methacrylate)-grafted polypropylene fibers

    International Nuclear Information System (INIS)

    Hayakawa, Kiyoshi; Taoda, Hiroshi; Kawase, Kaoru; Tazawa, Masato; Yamakita, Hiromi

    1986-01-01

    Thermal behavior of several kinds of poly (alkyl methacrylate) and polypropylene-g-poly (alkyl methacrylate) fibers prepared by γ-irradiation was investigated by thermogravimetric measurements with the intermittent analysis of the gaseous products. The degradation of poly (methyl methacrylate) proceeded according to the deploymerization mechanism reproducing the pristine monomer exclusively. The thermogram in inert atmosphere showed the features of a two-step depolymerization, while in air it showed no such a stepwise decrease with the elevating temperature. The dissolution-precipitation treatment of polymer seemed to affect the decomposition behavior. On other alkyl methacrylate polymers, the thermal decomposition generally proceeded also according to the depolymerization mechanism. But, for instance, at least two kinds of products besides its own monomer were formed from poly (isobutyl methacrylate), and their relative fractions differed with the temperature. Polypropylene-g-poly (alkyl methacrylate) fibers showed lowering of initiation temperature of decomposition with the increase in extent of the grafting, and their initiation temperatures of decomposition in air were lower than those in inert atmosphere. (author)

  15. Hydration of urea and alkylated urea derivatives

    Science.gov (United States)

    Kaatze, Udo

    2018-01-01

    Compressibility data and broadband dielectric spectra of aqueous solutions of urea and some of its alkylated derivatives have been evaluated to yield their numbers Nh of hydration water molecules per molecule of solute. Nh values in a broad range of solute concentrations are discussed and are compared to hydration numbers of other relevant molecules and organic ions. Consistent with previous results, it is found that urea differs from other solutes in its unusually small hydration number, corresponding to just one third of the estimated number of nearest neighbor molecules. This remarkable hydration behavior is explained by the large density φH of hydrogen bonding abilities offered by the urea molecule. In terms of currently discussed models of reorientational motions and allied dynamics in water and related associating liquids, the large density φH causes a relaxation time close to that of undisturbed water with most parts of water encircling the solute. Therefore only a small part of disturbed ("hydration") water is left around each urea molecule. Adding alkyl groups to the basic molecule leads to Nh values which, within the series of n-alkylurea derivatives, progressively increase with the number of methyl groups per solute. With n-butylurea, Nh from dielectric spectra, in conformity with many other organic solutes, slightly exceeds the number of nearest neighbors. Compared to such Nh values, hydration numbers from compressibility data are substantially smaller, disclosing incorrect assumptions in the formula commonly used to interpret the experimental compressibilities. Similar to other series of organic solutes, effects of isomerization have been found with alkylated urea derivatives, indicating that factors other than the predominating density φH of hydrogen bond abilities contribute also to the hydration properties.

  16. New Bioactive Alkyl Sulfates from Mediterranean Tunicates

    Directory of Open Access Journals (Sweden)

    Marialuisa Menna

    2012-10-01

    Full Text Available Chemical investigation of two species of marine ascidians, Aplidium elegans and Ciona edwardsii, collected in Mediterranean area, led to isolation of a series of alkyl sulfates (compounds 1–5 including three new molecules 1–3. Structures of the new metabolites have been elucidated by spectroscopic analysis. Based on previously reported cytotoxic activity of these type of molecules, compounds 1–3 have been tested for their effects on the growth of two cell lines, J774A.1 (BALB/c murine macrophages and C6 (rat glioma in vitro. Compounds 1 and 2 induced selective concentration-dependent mortality on J774A.1 cells.

  17. Dissolved and Suspended Polycyclic Aromatic Hydrocarbons (PAH in the North Aegean Sea

    Directory of Open Access Journals (Sweden)

    I. HATZIANESTIS

    2002-06-01

    Full Text Available The distribution and sources of polycyclic aromatic hydrocarbons (PAH were investigated in the seawater of the North Aegean Sea. The measured PAH concentrations in SPM are generally considered as elevated for open sea waters and were evenly distributed in the area. Their levels in the dissolved phase (1.6-33.0 ng/l were much higher than those encountered in the corresponding particulate phases (0.04-10.2 ng/l. The PAH patterns in both phases were dominated by the three ring aromatics and their alkylated derivatives, reflecting a predominant contribution of fossil hydrocarbons probably related to ship traffic, whereas no significant inputs from the rivers outfalling in the area were detected. In bottom waters PAH values were generally lower, whereas a higher depletion of the petroleum PAH in comparison with the pyrolytic ones according to depth was observed.

  18. Direct, Regioselective N-Alkylation of 1,3-Azoles.

    Science.gov (United States)

    Chen, Shuai; Graceffa, Russell F; Boezio, Alessandro A

    2016-01-04

    Regioselective N-alkylation of 1,3-azoles is a valuable transformation. Organomagnesium reagents were discovered to be competent bases to affect regioselective alkylation of various 1,3-azoles. Counterintuitively, substitution selectively occurred at the more sterically hindered nitrogen atom. Numerous examples are provided, on varying 1,3-azole scaffolds, with yields ranging from 25 to 95%.

  19. Alkylation of hydrothiophosphoryl compounds in conditions of interphase catalysis

    International Nuclear Information System (INIS)

    Aladzheva, I.M.; Odinets, I.L.; Petrovskij, P.V.; Mastryukova, T.A.; Kabachkin, M.I.

    1993-01-01

    A method of interphase catalysis permitted to develop a common method for synthesis of compounds with thiophosphoryl group. The effect of nature of hydrothiophosphoryl compound, alkylating agent, two-phase system and reaction conditions on alkylation product yields was investigated in detail

  20. Polyfluorinated alkyl phosphate ester surfactants - current knowledge and knowledge gaps

    DEFF Research Database (Denmark)

    Taxvig, Camilla; Rosenmai, Anna Kjerstine; Vinggaard, Anne Marie

    2014-01-01

    information on fluorochemicals. Polyfluorinated alkyl phosphate ester surfactants (PAPs) belong to the group of polyfluorinated alkyl surfactants. They have been detected in indoor dust and are widely used in food-contact materials, from which they have the ability to migrate into food. Toxicological data...

  1. dialkylated perylene diimides in poly(alkyl methacrylate) films.

    Indian Academy of Sciences (India)

    lene diimides in films of poly(alkyl methacrylate)s (PAMAs) with 5 different alkyl groups and in a 'model solvent' ... indicate that the perylenes can be used as a complementary probe of local polymer chain dynamics, but they are ... can be designed to allow a greater or lesser interaction with an anisotropic host matrix. Also ...

  2. Preparation of trialkylindium by alkylation of metallic indium

    International Nuclear Information System (INIS)

    Eremeev, I.V.; Danov, S.M.; Sakhipov, V.R.

    1995-01-01

    The investigation results on production of trialkyl indium by alkylation of metallic indium are presented. In contradistinction to the known techniques for the production of trialkyls on indium by alkylation it is suggested to separate the synthesis into two steps. At the first step indium is alkylated by alkylhalide to alkyl indium halide, and at the second alkylation is carried out using. Grignard reagent. The techniques for preparation of trimethyl- and triethylindium, developed on the bases of this scheme, are noted for good reproducibility, allow to preclude, agglomeration of indium during the synthesis, as well as to reduce the consumption coefficients, and amounts, of the introduced starting reagents, i.e. magnesium and alkylhalide. Refs. 16

  3. Nanostructured poly(benzimidazole membranes by N-alkylation

    Directory of Open Access Journals (Sweden)

    J. Weber

    2014-01-01

    Full Text Available Modification of poly(benzimidazole (PBI by N-alkylation leads to polymers capable of undergoing microphase separation. Polymers with different amounts of C18 alkyl chains have been prepared. The polymers were analyzed by spectroscopy, thermal analysis, electron microscopy and X-ray scattering. The impact of the amount of alkyl chains on the observed microphase separation was analyzed. Membranes prepared from the polymers do show microphase separation, as evidenced by scattering experiments. While no clear morphology could be derived for the domains in the native state, evidence for the formation of lamellar morphologies upon doping with phosphoric acid is provided. Finally, the proton conductivity of alkyl-modified PBI is compared with that of pure PBI, showing that the introduction of alkyl side chains does not result in significant conductivity changes.

  4. Application of C18-functional magnetic nanoparticles for extraction of aromatic amines from human urine.

    Science.gov (United States)

    Jiang, Chunzhu; Sun, Ying; Yu, Xi; Gao, Yan; Zhang, Lei; Wang, Yuanpeng; Zhang, Hanqi; Song, Daqian

    2014-02-01

    In this paper, a novel method using C18-functional ultrafine magnetic silica nanoparticles (C18-UMS NPs) as adsorbents was developed for rapid extraction and enrichment of aromatic amines from urine. C18-UMS NPs were prepared by chemical coprecipitation, silanization and alkylation. The aromatic amines can be adsorbed on C18-UMS NPs and isolated easily from the matrix with an external magnetic field. After desorption with acetonitrile, the aromatic amines were determined by ultra fast liquid chromatography. The experimental parameters, such as pH value of sample solution, amount of C18-UMS NPs, extraction time, type and volume of desorption solvent, and desorption time were optimized. The analytical performances of the present method were also evaluated. The limits of detection for 1-aminonaphthalene, 4-aminobiphenyl, 4,4'-diaminodiphenylmethane and 4-aminophenylthioether were 1.3, 0.88, 1.1 and 1.1 ng mL(-1), respectively. The results showed that the present method was simple, highly efficient and rapid for the extraction and enrichment of aromatic amines from urine. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Estrogenic Activity of Mineral Oil Aromatic Hydrocarbons Used in Printing Inks.

    Directory of Open Access Journals (Sweden)

    Patrick Tarnow

    Full Text Available The majority of printing inks are based on mineral oils (MOs which contain complex mixtures of saturated and aromatic hydrocarbons. Consumer exposure to these oils occurs either through direct skin contacts or, more frequently, as a result of MO migration into the contents of food packaging that was made from recycled newspaper. Despite this ubiquitous and frequent exposure little is known about the potential toxicological effects, particularly with regard to the aromatic MO fractions. From a toxicological point of view the huge amount of alkylated and unsubstituted compounds therein is reason for concern as they can harbor genotoxicants as well as potential endocrine disruptors. The aim of this study was to assess both the genotoxic and estrogenic potential of MOs used in printing inks. Mineral oils with various aromatic hydrocarbon contents were tested using a battery of in vitro assays selected to address various endpoints such as estrogen-dependent cell proliferation, activation of estrogen receptor α or transcriptional induction of estrogenic target genes. In addition, the comet assay has been applied to test for genotoxicity. Out of 15 MOs tested, 10 were found to potentially act as xenoestrogens. For most of the oils the effects were clearly triggered by constituents of the aromatic hydrocarbon fraction. From 5 oils tested in the comet assay, 2 showed slight genotoxicity. Altogether it appears that MOs used in printing inks are potential endocrine disruptors and should thus be assessed carefully to what extent they might contribute to the total estrogenic burden in humans.

  6. Cu(I)-Catalyzed Enantioselective Friedel-Crafts Alkylation of Indoles with 2-Aryl-N-sulfonylaziridines as Alkylating Agents.

    Science.gov (United States)

    Ge, Chen; Liu, Ren-Rong; Gao, Jian-Rong; Jia, Yi-Xia

    2016-07-01

    A highly enantioselective Friedel-Crafts alkylation of indoles with N-sulfonylaziridines as alkylating agents has been developed by utilizing the complex of Cu(CH3CN)4BF4/(S)-Segphos as a catalyst. A range of optically active tryptamine derivatives are obtained in good to excellent yields and enantioselectivities (up to >99% ee) via a kinetic resolution process.

  7. source apportionment and distribution of polycyclic aromatic

    African Journals Online (AJOL)

    PTDFSA11_Laptop

    pyrogenic-derived from incomplete combustion of recent. (e.g., biomass .... aromatic hydrocarbons (PAHs) used as internal standards and surrogates: ..... w ood. Combustion petroleum petroleum petroleum. (a). SOURCE APPORTIONMENT AND DISTRIBUTION OF POLYCYCLIC AROMATIC HYDROCARBONS. 141 ...

  8. An active site aromatic triad in Escherichia coli DNA Pol IV coordinates cell survival and mutagenesis in different DNA damaging agents.

    Directory of Open Access Journals (Sweden)

    Ryan W Benson

    Full Text Available DinB (DNA Pol IV is a translesion (TLS DNA polymerase, which inserts a nucleotide opposite an otherwise replication-stalling N(2-dG lesion in vitro, and confers resistance to nitrofurazone (NFZ, a compound that forms these lesions in vivo. DinB is also known to be part of the cellular response to alkylation DNA damage. Yet it is not known if DinB active site residues, in addition to aminoacids involved in DNA synthesis, are critical in alkylation lesion bypass. It is also unclear which active site aminoacids, if any, might modulate DinB's bypass fidelity of distinct lesions. Here we report that along with the classical catalytic residues, an active site "aromatic triad", namely residues F12, F13, and Y79, is critical for cell survival in the presence of the alkylating agent methyl methanesulfonate (MMS. Strains expressing dinB alleles with single point mutations in the aromatic triad survive poorly in MMS. Remarkably, these strains show fewer MMS- than NFZ-induced mutants, suggesting that the aromatic triad, in addition to its role in TLS, modulates DinB's accuracy in bypassing distinct lesions. The high bypass fidelity of prevalent alkylation lesions is evident even when the DinB active site performs error-prone NFZ-induced lesion bypass. The analyses carried out with the active site aromatic triad suggest that the DinB active site residues are poised to proficiently bypass distinctive DNA lesions, yet they are also malleable so that the accuracy of the bypass is lesion-dependent.

  9. Carenium—Calkyl Bond Making and Breaking: Key Process in the Platinum-Mediated Caryl—Calkyl Bond Formation. Analogies to Organic Electrophilic Aromatic Substitution

    NARCIS (Netherlands)

    Koten, G. van; Albrecht, M.A.; Spek, A.L.

    2001-01-01

    The reaction of cationic platinum aqua complexes 2 [Pt(C6H2{CH2NMe2}2-E-4)(OH2)](X') (X' = SO3CF3, BF4) with alkyl halides RX gave various air-stable arenium complexes 3-5 containing a new C-C bond (R = Me, 3; Et, 4; Bn, 5). Electron-releasing oxo-substituents on the aromatic ligand (E = e.g., OH,

  10. Selective Hydrodeoxygenation of Alkyl Lactates to Alkyl Propionates with Fe-based Bimetallic Supported Catalysts

    DEFF Research Database (Denmark)

    Khokarale, Santosh Govind; He, Jian; Schill, Leonhard

    2018-01-01

    significantly when using Fe-Ni/ZrO2 instead of Fe/ZrO2 alone. Moreover, the ZrO2 support contributed to improve the yield as a phase transition of ZrO2 from tetragonal to monoclinic occurred after metal doping giving rise to fine dispersion of the Fe and Ni on the ZrO2 , resulting in a higher catalytic activity...... of the material. Interestingly, it was observed that Fe-Ni/ZrO2 also effectively catalyzed methanol reforming to produce H2 in situ, followed by HDO of ML, yielding 60 % MP at 220 °C with 50 bar N2 instead of H2. Fe-Ni/ZrO2 also catalyzed HDO of other short-chain alkyl lactates to the corresponding alkyl...

  11. Bifunctional RuII -Complex-Catalysed Tandem C-C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents.

    Science.gov (United States)

    Roy, Bivas Chandra; Chakrabarti, Kaushik; Shee, Sujan; Paul, Subhadeep; Kundu, Sabuj

    2016-12-12

    Catalytic activities of a series of functional bipyridine-based Ru II complexes in β-alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional Ru II complex (3 a) bearing 6,6'-dihydroxy-2,2'-bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol %) dehydrogenative carbon-carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of β-alkylated secondary alcohols this protocol is a rare one-pot strategy using a metal-ligand cooperative Ru II system. Remarkably, complex 3 a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Formyl-d aromatic aldehydes

    International Nuclear Information System (INIS)

    Chancellor, T.; Quill, M.; Bergbreiter, D.E.; Newcomb, M.

    1978-01-01

    A simple exchange reaction for preparation of aldehydes labeled with deuterium at the formyl carbon is described. It can be successfully accomplished with several aromatic aldehydes, a catalytic or stoichiometric amount of either potassium cyanide or a thiazolium salt, a weak Lewis base, and deuterium oxide as the deuterium source

  13. Converting lignin to aromatics: step by step

    NARCIS (Netherlands)

    Strassberger, Z.I.

    2014-01-01

    Lignin, the glue that holds trees together, is the most abundant natural resource of aromatics. In that respect, it is a far more advanced resource than crude oil. This is because lignin already contains the aromatic functional groups. Thus, catalytic conversion of lignin to high-value aromatics is

  14. Cytotoxicity of Poly(Alkyl Cyanoacrylate Nanoparticles

    Directory of Open Access Journals (Sweden)

    Einar Sulheim

    2017-11-01

    Full Text Available Although nanotoxicology has become a large research field, assessment of cytotoxicity is often reduced to analysis of one cell line only. Cytotoxicity of nanoparticles is complex and should, preferentially, be evaluated in several cell lines with different methods and on multiple nanoparticle batches. Here we report the toxicity of poly(alkyl cyanoacrylate nanoparticles in 12 different cell lines after synthesizing and analyzing 19 different nanoparticle batches and report that large variations were obtained when using different cell lines or various toxicity assays. Surprisingly, we found that nanoparticles with intermediate degradation rates were less toxic than particles that were degraded faster or more slowly in a cell-free system. The toxicity did not vary significantly with either the three different combinations of polyethylene glycol surfactants or with particle size (range 100–200 nm. No acute pro- or anti-inflammatory activity on cells in whole blood was observed.

  15. Optimization of the alkyl side chain length of fluorine-18-labeled 7α-alkyl-fluoroestradiol

    International Nuclear Information System (INIS)

    Okamoto, Mayumi; Shibayama, Hiromitsu; Naka, Kyosuke; Kitagawa, Yuya; Ishiwata, Kiichi; Shimizu, Isao; Toyohara, Jun

    2016-01-01

    Introduction: Several lines of evidence suggest that 7α-substituted estradiol derivatives bind to the estrogen receptor (ER). In line with this hypothesis, we designed and synthesized 18 F-labeled 7α-fluoroalkylestradiol (Cn-7α-[ 18 F]FES) derivatives as molecular probes for visualizing ERs. Previously, we successfully synthesized 7α-(3-[ 18 F]fluoropropyl)estradiol (C3-7α-[ 18 F]FES) and showed promising results for quantification of ER density in vivo, although extensive metabolism was observed in rodents. Therefore, optimization of the alkyl side chain length is needed to obtain suitable radioligands based on Cn-7α-substituted estradiol pharmacophores. Methods: We synthesized fluoromethyl (23; C1-7α-[ 18 F]FES) to fluorohexyl (26; C6-7α-[ 18 F]FES) derivatives, except fluoropropyl (C3-7α-[ 18 F]FES) and fluoropentyl derivatives (C5-7α-[ 18 F]FES), which have been previously synthesized. In vitro binding to the α-subtype (ERα) isoform of ERs and in vivo biodistribution studies in mature female mice were carried out. Results: The in vitro IC 50 value of Cn-7α-FES tended to gradually decrease depending on the alkyl side chain length. C1-7α-[ 18 F]FES (23) showed the highest uptake in ER-rich tissues such as the uterus. Uterus uptake also gradually decreased depending on the alkyl side chain length. As a result, in vivo uterus uptake reflected the in vitro ERα affinity of each compound. Bone uptake, which indicates de-fluorination, was marked in 7α-(2-[ 18 F]fluoroethyl)estradiol (C2-7α-[ 18 F]FES) (24) and 7α-(4-[ 18 F]fluorobutyl)estradiol (C4-7α-[ 18 F]FES) (25) derivatives. However, C1-7α-[ 18 F]FES (23) and C6-7α-[ 18 F]FES (26) showed limited uptake in bone. As a result, in vivo bone uptake (de-fluorination) showed a bell-shaped pattern, depending on the alkyl side chain length. C1-7α-[ 18 F]FES (23) showed the same levels of uptake in uterus and bone compared with those of 16α-[ 18 F]fluoro-17β-estradiol. Conclusions: The optimal alkyl

  16. A yeast mutant specifically sensitive to bifunctional alkylation

    International Nuclear Information System (INIS)

    Ruhland, A.; Kircher, M.; Wilborn, F.; Brendel, M.

    1981-01-01

    A mutation that specifically confers sensitivity to bi- and tri-functional alkylating agents is presented. No or little cross-sensitivity to radiation or monofunctional agents could be detected. Sensitivity does not seem to be due to preferential alkylation of mutant DNA as parent and mutant strain exhibit the same amount of DNA alkylation and the same pattern of DNA lesions including interstrand crosslinks. The mutation is due to a defect in a nuclear gene which has been designated SNM1 (sensitive to nitrogen mustard); it may control an important step in the repair of DNA interstrand crosslinks (orig.(AJ)

  17. An adaptive response to alkylating agents in Aspergillus nidulans.

    Science.gov (United States)

    Hooley, P; Shawcross, S G; Strike, P

    1988-11-01

    A simple method is described for demonstrating adaptation to alkylation damage in Aspergillus nidulans. One wild type, two MNNG-sensitive, and one MNNG-resistant strain all showed improvement in colony growth when challenged with MNNG following appropriate inducing pretreatments. Other alkylating agents (MMS, EMS) could also adapt mycelium to later MNNG challenge, while 4NQO and UV could not. The inducible effect was not transmissible through conidia. A standard reversion assay based upon methG proved impractical for studying mutation frequencies during alkylation treatments owing to variations in MNNG resistance amongst revertants.

  18. Structure-activity relationships of 2alpha-substituted androstenedione analogs as aromatase inhibitors and their aromatization reactions.

    Science.gov (United States)

    Numazawa, Mitsuteru; Handa, Wakako; Hasegawa, Chie; Takahashi, Madoka

    2005-12-01

    Aromatase catalyzes the conversion of androstenedione (1a, AD) to estrone through three sequential oxygenations of the 19-methyl group. To gain insight into the spatial nature of the AD binding (active) site of aromatase in relation to the catalytic function of the enzyme, we tested for the ability of 2alpha-substituted (halogeno, alkyl, hydroxy, and alkoxy) ADs (1b-1i) to inhibit aromatase in human placental microsomes as well as their ability to serve as a substrate for the enzyme. All of the steroids inhibited the enzyme in a competitive manner with the apparent K(i)'s ranging from 45 to 1150 nM. 2alpha-Halogeno (F, Cl, and Br) and 2alpha-alkyl (CH3 and CH2CH3) steroids 1b-1f were powerful to good inhibitors (Ki=45-171 nM) whereas steroids 1g-1i, having an oxygen function (hydroxy or alkoxy) at C-2alpha, were poor inhibitors (Ki=670-1150 nM). Aromatization of some of the steroids with placental microsomes was analyzed by gas chromatography-mass spectrometry, indicating that the aromatization rate of the bromide 1d was about two-fold that of the natural substrate AD and that of 2alpha-methoxide 1h was similar to that of AD. Kinetic analysis of the aromatization of androgens revealed that a good substrate was not essentially a good inhibitor for aromatase.

  19. Structural Elucidation of Z- and E- Isomers of 5-Alkyl-4-ethoxycarbonyl-5-(4`-chlorophenyl-3-oxa-4-pentenoic Acids

    Directory of Open Access Journals (Sweden)

    H. M. F. Madkour

    2000-05-01

    Full Text Available Z- and E-isomers of 5-alkyl-4-ethoxycarbonyl-5-(4`-chlorophenyl-3-oxa-4-pentenoic acids were prepared via the condensation of p-chloroacetophenone and/or pchloropropiophenone with diethyl-2,2`-oxydiacetate in the presence of sodium hydride as a basic catalyst. The Z-isomers of 2a and 2b were found to be predominant. The behaviour of the corresponding anhydrides towards the action of hydrazine, phenylhydrazine, primary aromatic amines, hydrocarbons and ethanolysis has also been investigated. The structures and configurations of the products have been elucidated by chemical and spectroscopic means.

  20. Sources of polycyclic aromatic hydrocarbons (PAHs) pollution in marine sediment from Tuanku Abdul Rahman National Park, Sabah

    International Nuclear Information System (INIS)

    Mohd Suhaimi Elias; Abdul Khalid Wood; Zaleha Hashim; Mohd Suhaimi Hamzah; Shamsiah Abdul Rahman; Nazaratul Ashifa Abdullah Salim

    2011-01-01

    The concentrations of parent and alkyl Polycyclic Aromatic Hydrocarbons (PAHs) in marine sediment samples collected from Tuanku Abdul Rahman National Park, Sabah were determined by using GC-MS. The ratio of anthracene to anthracene plus phenanthrene, fluoranthene to fluoranthene plus pyrene, benz[a]anthracene to benz[a]anthracene plus chrysene and indeno[1,2,3-cd]pyrene to indeno[1,2,3-cd]pyrene plus benzo[g,h,i]perylene, compounds were used to identify the sources of PAHs pollution. The total concentration of parent and alkyl PAHs are ranged from 121.7 to 191.5 ng/ g dry weight. The concentrations of PAHs pollution in sediments were categorised as a moderate polluted. The ratio values of PAHs compound indicate the origin source of PAHs pollutions in marine sediment sample of Tuanku Abdul Rahman National Park were originated from fossil fuel combustion (pyrolytic). (author)

  1. Alkylsilyl Peroxides as Alkylating Agents in the Copper-Catalyzed Selective Mono-N-Alkylation of Primary Amides and Arylamines.

    Science.gov (United States)

    Sakamoto, Ryu; Sakurai, Shunya; Maruoka, Keiji

    2017-07-06

    The copper-catalyzed selective mono-N-alkylation of primary amides or arylamines using alkylsilyl peroxides as alkylating agents is reported. The reaction proceeds under mild reaction conditions and exhibits a broad substrate scope with respect to the alkylsilyl peroxides, as well as to the primary amides and arylamines. Mechanistic studies suggest that the present reaction should proceed through a free-radical process that includes alkyl radicals generated from the alkylsilyl peroxides. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Regulation of DNA Alkylation Damage Repair: Lessons and Therapeutic Opportunities.

    Science.gov (United States)

    Soll, Jennifer M; Sobol, Robert W; Mosammaparast, Nima

    2017-03-01

    Alkylation chemotherapy is one of the most widely used systemic therapies for cancer. While somewhat effective, clinical responses and toxicities of these agents are highly variable. A major contributing factor for this variability is the numerous distinct lesions that are created upon alkylation damage. These adducts activate multiple repair pathways. There is mounting evidence that the individual pathways function cooperatively, suggesting that coordinated regulation of alkylation repair is critical to prevent toxicity. Furthermore, some alkylating agents produce adducts that overlap with newly discovered methylation marks, making it difficult to distinguish between bona fide damaged bases and so-called 'epigenetic' adducts. Here, we discuss new efforts aimed at deciphering the mechanisms that regulate these repair pathways, emphasizing their implications for cancer chemotherapy. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Detection of Alkylating Agents using Electrical and Mechanical Means

    International Nuclear Information System (INIS)

    Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Eichen, Yoav; Tal, Shay; Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir

    2011-01-01

    Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

  4. Direct N-alkylation of unprotected amino acids with alcohols

    NARCIS (Netherlands)

    Yan, Tao; Feringa, Ben L; Barta, Katalin

    2017-01-01

    N-alkyl amino acids find widespread application as highly valuable, renewable building blocks. However, traditional synthesis methodologies to obtain these suffer from serious limitations, providing a major challenge to develop sustainable alternatives. We report the first powerful catalytic

  5. Regeneration of a deactivated USY alkylation catalyst using supercritical isobutane

    Energy Technology Data Exchange (ETDEWEB)

    Daniel M. Ginosar; David N. Ghompson; Kyle C. Burch

    2005-01-01

    Off-line, in-situ alkylation activity recovery from a completely deactivated solid acid catalyst was examined in a continuous-flow reaction system employing supercritical isobutane. A USY zeolite catalyst was initially deactivated during the liquid phase alkylation of butene with isobutane in a single-pass reactor and then varying amounts of alkylation activity were recovered by passing supercritical isobutane over the catalyst bed at different reactivation conditions. Temperature, pressure and regeneration time were found to play important roles in the supercritical isobutane regeneration process when applied to a completely deactivated USY zeolite alkylation catalyst. Manipulation of the variables that influence solvent strength, diffusivity, surface desorption, hydride transfer rates, and coke aging, strongly influence regeneration effectiveness.

  6. Fluorinated Alkyl Ether Epoxy Resin Compositions and Applications Thereof

    Science.gov (United States)

    Wohl, Christopher J. (Inventor); Connell, John W. (Inventor); Smith, Joseph G. (Inventor); Siochi, Emilie J. (Inventor); Gardner, John M. (Inventor); Palmieri, Frank M. (Inventor)

    2017-01-01

    Epoxy resin compositions prepared using amino terminated fluoro alkyl ethers. The epoxy resin compositions exhibit low surface adhesion properties making them useful as coatings, paints, moldings, adhesives, and fiber reinforced composites.

  7. Iminium Salts by Meerwein Alkylation of Ehrlich’s Aldehyde

    Directory of Open Access Journals (Sweden)

    Gerhard Laus

    2013-03-01

    Full Text Available 4-(Dimethylaminobenzaldehyde is alkylated at the N atom by dialkyl sulfates, MeI, or Me3O BF4. In contrast, ethylation by Et3O BF4 occurs selectively at the O atom yielding a quinoid iminium ion. 4-(Diethylaminobenzaldehyde is alkylated only at O by either Et or Me oxonium reagent. The iminium salts are prone to hydrolysis giving the corresponding hydrotetrafluoroborates. Five crystal structures were determined.

  8. Enantioselective γ-Alkylation of α,β-Unsaturated Malonates and Ketoesters by a Sequential Ir-Catalyzed Asymmetric Allylic Alkylation/Cope Rearrangement

    OpenAIRE

    Liu, Wen-Bo; Okamoto, Noriko; Alexy, Eric J.; Hong, Allen Y.; Tran, Kristy; Stoltz, Brian M.

    2016-01-01

    A catalytic, enantioselective ? -alkylation of ?,?-unsaturated malonates and ketoesters is reported. This strategy entails a highly regio- and enantioselective iridium-catalyzed ?-alkylation of an extended enolate, and a subsequent translocation of chirality to the ?-position via a Cope rearrangement.

  9. The direct aromatization of methane

    Energy Technology Data Exchange (ETDEWEB)

    Marcelin, G.; Oukaci, R.; Migone, R.A.; Kazi, A.M. [Altamira Instruments, Pittsburgh, PA (United States)

    1995-12-31

    The thermal decomposition of methane shows significant potential as a process for the production of higher unsaturated and aromatic hydrocarbons when the extent of the reaction is limited. Thermodynamic calculations have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that cooling the product and reacting gases as the reaction proceeds can significantly reduce or eliminate the formation of solid carbon and heavier (C{sub 10+}) materials. Much work remains to be done in optimizing the quenching process and this is one of the goals of this program. Means to lower the temperature of the reaction are being studied as this result in a more feasible commercial process due to savings realized in energy and material of construction costs. The use of free-radical generators and catalysts will be investigated as a means of lowering the reaction temperature thus allowing faster quenching. It is highly likely that such studies will lead to a successful direct methane to higher hydrocarbon process.

  10. Dehalogenation of halogenated aromatic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Griller, D.; Hawari, J.A.; McPhee, D.J.

    1992-03-03

    A process is disclosed for dehalogenating aromatic halogenated compounds, comprising reacting an alkali metal with the halogenated aromatic material in the presence of a liquid hydrosiloxane until substantially all of the halogen has reacted, leaving the aromatic moiety in non-halogenated form. Preferably a non-halogenated non-aqueous polar solvent or diluent is present during the reaction. The excess alkali metal can be reacted with added termination agent, and excess hydrosiloxane can be precipitated and the solids separated. According to a further aspect of the invention, a kit is provided for carrying out the above dehalogenation process. The kit comprises a container containing alkali metal, a container containing liquid hydrosiloxane, or one container containing both the alkali metal and the hydrosiloxane. The starting material to be dehalogenated, in most applications of the process, will be polychlorinated biphenyls alone or as mixtures with various oils such as transformer oils. The alkali metal may be Li, Na, or K, and the hydrosiloxane should be a liquid miscible with the starting material, preferably a polyorganohydrosiloxane of relatively low molecular weight. Experiments are described to illustrate the process of the invention. It is shown that the process of the invention provides significantly improved dehalogenations at ambient temperatures and may be used for destruction of polychlorinated biphenyls to the point where they can no longer be detected by gas chromatography.

  11. Chemistry of Furan Conversion into Aromatics and Olefins over HZSM-5: A Model Biomass Conversion Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yu-Ting; Huber, George W.

    2011-06-03

    ), decarbonylation (e.g., furan forms CO and allene), oligomerization (allene forms olefins and aromatics plus hydrogen), and alkylation (e.g., furan plus olefins). The product distribution was far from thermodynamic equilibrium.

  12. Final Technical Report [Development of Catalytic Alkylation and Fluoroalkylation Methods

    Energy Technology Data Exchange (ETDEWEB)

    Vicic, David A.

    2014-05-01

    In the early stages of this DOE-funded research project, we sought to prepare and study a well-defined nickel-alkyl complex containing tridentate nitrogen donor ligands. We found that reaction of (TMEDA)NiMe2 (1) with terpyridine ligand cleanly led to the formation of (terpyridyl)NiMe (2), which we also determined to be an active alkylation catalyst. The thermal stability of 2 was unlike that seen for any of the active pybox ligands, and enabled a number of key studies on alkyl transfer reactions to be performed, providing new insights into the mechanism of nickel-mediated alkyl-alkyl cross-coupling reactions. In addition to the mechanistic studies, we showed that the terpyridyl nickel compounds can catalytically cross-couple alkyl iodides in yields up to 98% and bromides in yields up to 46 %. The yields for the bromides can be increased up to 67 % when the new palladium catalyst [(tpy’)Pd-Ph]I is used. The best route to the targeted [(tpy)NiBr] (1) was found to involve the comproportionation reaction of [(dme)NiBr{sub 2}] and [Ni(COD){sub 2}] in the presence of two equivalents of terpyridine. This reaction was driven to high yields of product formation (72 % isolated) by the precipitation of 1 from THF solvent.

  13. Salvage of Failed Protein Targets by Reductive Alkylation

    Science.gov (United States)

    Tan, Kemin; Kim, Youngchang; Hatzos-Skintges, Catherine; Chang, Changsoo; Cuff, Marianne; Chhor, Gekleng; Osipiuk, Jerzy; Michalska, Karolina; Nocek, Boguslaw; An, Hao; Babnigg, Gyorgy; Bigelow, Lance; Joachimiak, Grazyna; Li, Hui; Mack, Jamey; Makowska-Grzyska, Magdalena; Maltseva, Natalia; Mulligan, Rory; Tesar, Christine; Zhou, Min; Joachimiak, Andrzej

    2014-01-01

    The growth of diffraction-quality single crystals is of primary importance in protein X-ray crystallography. Chemical modification of proteins can alter their surface properties and crystallization behavior. The Midwest Center for Structural Genomics (MCSG) has previously reported how reductive methylation of lysine residues in proteins can improve crystallization of unique proteins that initially failed to produce diffraction-quality crystals. Recently, this approach has been expanded to include ethylation and isopropylation in the MCSG protein crystallization pipeline. Applying standard methods, 180 unique proteins were alkylated and screened using standard crystallization procedures. Crystal structures of 12 new proteins were determined, including the first ethylated and the first isopropylated protein structures. In a few cases, the structures of native and methylated or ethylated states were obtained and the impact of reductive alkylation of lysine residues was assessed. Reductive methylation tends to be more efficient and produces the most alkylated protein structures. Structures of methylated proteins typically have higher resolution limits. A number of well-ordered alkylated lysine residues have been identified, which make both intermolecular and intramolecular contacts. The previous report is updated and complemented with the following new data; a description of a detailed alkylation protocol with results, structural features, and roles of alkylated lysine residues in protein crystals. These contribute to improved crystallization properties of some proteins. PMID:24590719

  14. Regioselective 1-N-Alkylation and Rearrangement of Adenosine Derivatives.

    Science.gov (United States)

    Oslovsky, Vladimir E; Drenichev, Mikhail S; Mikhailov, Sergey N

    2015-01-01

    Several methods for the preparation of some N(6)-substituted adenosines based on selective 1-N-alkylation with subsequent Dimroth rearrangement were developed. The proposed methods seem to be effective for the preparation of natural N(6)-isopentenyl- and N(6)-benzyladenosines, which are known to possess pronounced biological activities. Direct 1-N-alkylation of 2',3',5'-tri-O-acetyladenosine and 3',5'-di-O-acetyl-2'-deoxyadenosine with alkyl halides in N,N-dimethylformamide (DMF) in the presence of BaCO3 and KI gave 1-N-substituted derivatives with quantitative yields, whereas 1-N-alkylation of adenosine was accompanied by significant O-alkylation. Moreover, the reaction of trimethylsilyl derivatives of N(6)-acetyl-2',3',5'-tri-O-acetyladenosine and N(6)-acetyl-3',5'-di-O-acetyl-2'-deoxyadenosine with alkyl halides leads to the formation of the stable 1-N-substituted adenosines. Dimroth rearrangement of 1-N-substituted adenosines in aqueous ammonia yields pure N(6)-substituted adenosines.

  15. Alcohols as alkylating agents in heteroarene C-H functionalization

    Science.gov (United States)

    Jin, Jian; MacMillan, David W. C.

    2015-09-01

    Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage. One of the core principles underlying DNA biosynthesis is the radical-mediated elimination of H2O to deoxygenate ribonucleotides, an example of `spin-centre shift', during which an alcohol C-O bond is cleaved, resulting in a carbon-centred radical intermediate. Although spin-centre shift is a well-understood biochemical process, it is underused by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylation reactions using alcohols as radical precursors. Because conventional radical-based alkylation methods require the use of stoichiometric oxidants, increased temperatures or peroxides, a mild protocol using simple and abundant alkylating agents would have considerable use in the synthesis of diversely functionalized pharmacophores. Here we describe the development of a dual catalytic alkylation of heteroarenes, using alcohols as mild alkylating reagents. This method represents the first, to our knowledge, broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer catalysis. The value of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone.

  16. Alcohols as alkylating agents in heteroarene C–H functionalization

    Science.gov (United States)

    Jin, Jian; MacMillan, David W. C.

    2015-01-01

    Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage1. One of the core principles that underlies DNA biosynthesis is the radical-mediated elimnation of H2O to deoxygenate ribonucleotides, an example of ‘spin-center shift’ (SCS)2, during which an alcohol C–O bond is cleaved, resulting in a carbon-centered radical intermediate. While SCS is a well-understood biochemical process, it is underutilized by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylations using alcohols as radical precursors. Considering traditional radical-based alkylation methods require the use of stoichiometric oxidants, elevated temperatures, or peroxides3–7, the development of a mild protocol using simple and abundant alkylating agents would have significant utility in the synthesis of diversely functionalized pharmacophores. In this manuscript, we describe the successful execution of this idea via the development of a dual catalytic alkylation of heteroarenes using alcohols as mild alkylating reagents. This method represents the first broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer (HAT) catalysis. The utility of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone. PMID:26308895

  17. Coordinative saturation and the chemistry of triscyclopentadienyl thorium (IV) alkyls and alkenyls

    International Nuclear Information System (INIS)

    Wachter, W.A.

    1976-01-01

    Air- and moisture-sensitive (C 5 H 5 ) 3 Th(IV)R compounds (R = alkyl, alkenyl) were prepared by reacting (C 5 H 5 ) 3 Th(IV)Cl with the corresponding Grignard or lithium reagent in toluene at -78 0 . They were characterized by elemental analysis, molecular weight, and pmr, infrared, and Raman spectroscopy. The fluxional behavior in the nmr indicates a sigmatropic rearrangement with an activation energy of 8 to 9 kcal/mole. Alcoholysis is faster and more selective for alkane formation than in the analogous uranium system. In aromatic solvents the compounds exhibit first-order decomposition kinetics. Relative thermal stabilities are neopentyl > allyl > n-butyl > 2-cis-2-butenyl > 2-trans-2-butenyl > i-propyl. Respective half-lives of these compounds at 167 0 C are 7500, 566, 96, 39, 21, and 7 hr. Alkanes are the major product for R = alkyl. Retention of configuration is noted for R = cis- and trans-2-butenyl. k/sub H//k/sub D/ is 2.4 for R = n-butyl. The results are consistent with coordinative saturation about the Th center blocking β-elimination. The solid product was also crystallized, and x-ray diffraction results reveal a bridged dimer ((C 5 H 5 ) 2 (C 5 H 4 )Th) 2 . To each Th are bound three rings in a pentahapto fashion and one ring, which is bound in a pentahapto fashion to the other Th center, in a monohapto fashion. These results suggest a short-lived intermediate, possibly an ylid, prior to dimerization. The photochemical decomposition of triscyclopentadienyl Th(IV) isopropyl leads to the formation of propene, propane, and an insoluble green solid. The solid analyzes as (C 15 H 15 Th) 2 , has a temperature-independent paramagnetism of 18.45 x 10 -4 cgs, and exhibits vibrational frequencies characteristic of pentahaptocyclopentadienyl ligands

  18. Lignin solubilization and aqueous phase reforming for the production of aromatic chemicals and hydrogen.

    Science.gov (United States)

    Zakzeski, Joseph; Weckhuysen, Bert M

    2011-03-21

    The solubilization and aqueous phase reforming of lignin, including kraft, soda, and alcell lignin along with sugarcane bagasse, at low temperatures (T≤498 K) and pressures (P≤29 bar) is reported for the first time for the production of aromatic chemicals and hydrogen. Analysis of lignin model compounds and the distribution of products obtained during the lignin aqueous phase reforming revealed that lignin was depolymerized through disruption of the abundant β-O-4 linkages and, to a lesser extent, the 5-5' carbon-carbon linkages to form monomeric aromatic compounds. The alkyl chains contained on these monomeric compounds were readily reformed to produce hydrogen and simple aromatic platform chemicals, particularly guaiacol and syringol, with the distribution of each depending on the lignin source. The methoxy groups present on the aromatic rings were subject to hydrolysis to form methanol, which was also readily reformed to produce hydrogen and carbon dioxide. The composition of the isolated yields of monomeric aromatic compounds and overall lignin conversion based on these isolated yields varied from 10-15% depending on the lignin sample, with the balance consisting of gaseous products and residual solid material. Furthermore, we introduce the use of a high-pressure autoclave with optical windows and an autoclave with ATR-IR sentinel for on-line in situ spectroscopic monitoring of biomass conversion processes, which provides direct insight into, for example, the solubilization process and aqueous phase reforming reaction of lignin. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. On the role of alkylating mechanisms, O-alkylation and DNA-repair in genotoxicity and mutagenicity of alkylating methanesulfonates of widely varying structures in bacterial systems.

    Science.gov (United States)

    Eder, E; Kütt, W; Deininger, C

    2001-07-31

    The Ames test and the SOS-chromotest are widely used bacterial mutagenicity/genotoxicity assays to test potential carcinogens. Though the molecular mechanisms leading to backmutations and to the induction of SOS-repair are in principle known the role of alkylation mechanisms, of different DNA-lesions and of DNA-repair is in parts still unknown. In this study we investigated 14 monofunctional methanesulfonates of widely varying structures for mutagenicity in Salmonella typhimurium strain TA 1535 sensitive for O(6)-guanine alkylation for comparison with strain TA 100 in order to obtain additional information on the role of alkylation mechanisms, formation of the procarcinogenic DNA-lesion O(6)-alkylguanine and the role of DNA-repair in induction of backmutation. The substances were also tested in the SOS-chromotest with Escherichia coli strain PQ 37 and strain PQ 243 lacking alkyl base glycosylases important for base excision repair in order to examine the role of alkylation mechanisms, of base excision repair and the role of O-alkyl and N-alkyl DNA-lesions on the induction of SOS-repair. The secondary methanesulfonates with very high S(N)1-reactivity isopropyl methanesulfonate and 2-butyl methanesulfonate showed highest mutagenicities in both strains. The higher substituted methanesulfonates with very high S(N)1-reactivity had lower mutagenic activities because of reduced half lives due to their high hydrolysis rates. A clear increase in mutagenicities in strain TA 100 was observed for the primary compounds methyl methanesulfonate and allyl methanesulfonate with very high S(N)2-reactivity. The primary compound phenylethyl methanesulfonate has a relatively high mutagenicity in both Salmonella strains which can be explained by an increased S(N)1-reactivity and by low repair of the O(6)-phenylethylguanine. Highest SOSIPs (SOS inducing potency) in strains PQ 37 and PQ 243 were found for methyl methanesulfonate and for the secondary compounds with high S(N)1-reactivity

  20. Spectroscopic Diagnosis of Excited-State Aromaticity: Capturing Electronic Structures and Conformations upon Aromaticity Reversal.

    Science.gov (United States)

    Oh, Juwon; Sung, Young Mo; Hong, Yongseok; Kim, Dongho

    2018-03-06

    Aromaticity, the special energetic stability derived from cyclic [4 n + 2]π-conjugated electronic structures, has been the topic of intense interest in chemistry because it plays a critical role in rationalizing molecular stability, reactivity, and physical/chemical properties. Recently, the pioneering work by Colin Baird on aromaticity reversal, postulating that aromatic (antiaromatic) character in the ground state reverses to antiaromatic (aromatic) character in the lowest excited triplet state, has attracted much scientific attention. The completely reversed aromaticity in the excited state provides direct insight into understanding the photophysical/chemical properties of photoactive materials. In turn, the application of aromatic molecules to photoactive materials has led to numerous studies revealing this aromaticity reversal. However, most studies of excited-state aromaticity have been based on the theoretical point of view. The experimental evaluation of aromaticity in the excited state is still challenging and strenuous because the assessment of (anti)aromaticity with conventional magnetic, energetic, and geometric indices is difficult in the excited state, which practically restricts the extension and application of the concept of excited-state aromaticity. Time-resolved optical spectroscopies can provide a new and alternative avenue to evaluate excited-state aromaticity experimentally while observing changes in the molecular features in the excited states. Time-resolved optical spectroscopies take advantage of ultrafast laser pulses to achieve high time resolution, making them suitable for monitoring ultrafast changes in the excited states of molecular systems. This can provide valuable information for understanding the aromaticity reversal. This Account presents recent breakthroughs in the experimental assessment of excited-state aromaticity and the verification of aromaticity reversal with time-resolved optical spectroscopic measurements. To

  1. Noncomparative scaling of aromaticity through electron itinerancy

    International Nuclear Information System (INIS)

    Paul, Satadal; Goswami, Tamal; Misra, Anirban

    2015-01-01

    Aromaticity is a multidimensional concept and not a directly observable. These facts have always stood in the way of developing an appropriate theoretical framework for scaling of aromaticity. In the present work, a quantitative account of aromaticity is developed on the basis of cyclic delocalization of π-electrons, which is the phenomenon leading to unique features of aromatic molecules. The stabilization in molecular energy, caused by delocalization of π-electrons is obtained as a second order perturbation energy for archetypal aromatic systems. The final expression parameterizes the aromatic stabilization energy in terms of atom to atom charge transfer integral, onsite repulsion energy and the population of spin orbitals at each site in the delocalized π-electrons. An appropriate computational platform is framed to compute each and individual parameter in the derived equation. The numerical values of aromatic stabilization energies obtained for various aromatic molecules are found to be in close agreement with available theoretical and experimental reports. Thus the reliable estimate of aromaticity through the proposed formalism renders it as a useful tool for the direct assessment of aromaticity, which has been a long standing problem in chemistry

  2. Alkyl-halogenide promoted ionic liquid catalysis of isobutane/butene-alkylation

    Energy Technology Data Exchange (ETDEWEB)

    Schilder, L.; Korth, W.; Jess, A. [Bayreuth Univ. (Germany). Dept. of Chemical Engineering

    2011-07-01

    The effect of two different types of promoters on the performance of Lewis-acidic chloroaluminate ionic liquid catalysts was studied for liquid liquid biphasic isobutane/2-butene alkylation. In particular, the activity and selectivity of such catalytic systems was investigated. Experimental results obtained from a batch reactor show, that tert-butyl halides increase the reaction rate significantly and shift the C8-selectivity towards the desired high-octane trimethylpentanes (TMPs). But, secondary reactions like oligomerization and cracking are not affected by the use of these promoters. (orig.)

  3. DNA minor groove targeted alkylating agents based on bisbenzimidazole carriers: synthesis, cytotoxicity and sequence-specificity of DNA alkylation.

    Science.gov (United States)

    Smaill, J B; Fan, J Y; Denny, W A

    1998-12-01

    A series of bisbenzimidazoles bearing a variety of alkylating agents [ortho- and meta-mustards, imidazolebis(hydroxymethyl), imidazolebis(methylcarbamate) and pyrrolebis(hydroxymethyl)], appended by a propyl linker chain, were prepared and investigated for sequence-specificity of DNA alkylation and their cytotoxicity. Previous work has shown that, for para-aniline mustards, a propyl linker is optimal for cytotoxicity. Alkaline cleavage assays using a variety of different labelled oligonucleotides showed that the preferred sequences for adenine alkylation were 5'-TTTANANAANN and 5'-ATTANANAANN (underlined bases show the drug alkylation sites), with AT-rich sequences required on both the 5' and 3' sides of the alkylated adenine. The different aniline mustards showed little variation in alkylation pattern and similar efficiencies of DNA cross-link formation despite the changes in orientation and positioning of the mustard, suggesting that the propyl linker has some flexibility. The imidazole- and pyrrolebis(hydroxymethyl) alkylators showed no DNA strand cleavage following base treatment, indicating that no guanine or adenine N3 or N7 adducts were formed. Using the PCR-based polymerase stop assay, these alkylators showed PCR blocks at 5'-C*G sites (the * nucleotide indicates the blocked site), particularly at 5'-TAC*GA 5'-AGC*GGA, and 5'-AGCC*GGT sequences, caused by guanine 2-NH2 lesions on the opposite strand. Only the (more reactive) imidazolebis(methylcarbamoyl) and pyrrolebis(hydroxymethyl) alkylators demonstrated interstrand cross-linking ability. All of the bifunctional mustards showed large (approximately 100-fold) increases in cytotoxicity over chlorambucil, with the corresponding monofunctional mustards being 20- to 60-fold less cytotoxic. These results suggest that in the mustards the propyl linker provides sufficient flexibility to achieve delivery of the alkylator to favoured (adenine N3) sites in the minor groove, regardless of its exact geometry with

  4. UV absorption spectra and kinetics for alkyl and alkyl peroxy radicals originating from di-tert-butyl ether

    DEFF Research Database (Denmark)

    Nielsen, O.J.; Sehested, J.; Langer, S.

    1995-01-01

    Alkyl, (CH3)(3)COC(CH3)(2)CH2, and alkyl peroxy, (CH3)(3)COC(CH3)(2)CH2O2, radicals from di-tert-butyl ether (DTBE), have been studied in the gas phase at 296 K. A pulse radiolysis UV absorption technique was used to measure the spectra and kinetics. Absorption cross sections were quantified over...

  5. Propargyl organometallic compounds. II. Alkylation of sodium derivatives of 1-alkyl-1-aryl-2-alkynes in liquid ammonia

    International Nuclear Information System (INIS)

    Libman, N.M.; Sevryukov, Yu.P.

    1987-01-01

    In most cases the alkylation of the sodium derivatives of 1-phenyl-1-alkyl-2-alkynes by methyl, ethyl, isopropyl, and tert-butyl bromides in liquid ammonia takes place preferentially at the sp 2 -hybridized carbon atom, and this leads to the formation of the corresponding acetylenes, The regioselectivity of the reaction is explained by the greater softness of the trigonal atom of the ambient propargyl anion and its smaller screening by the solvate shell compared with the diagonal atom

  6. Smectic assemblies in C₃-symmetric hexa-alkylated liquid crystals: transformation from smectogen to discogen via hydrogen bonding.

    Science.gov (United States)

    Park, Soyoung; Ryu, Mi-Hee; Shin, Tae Joo; Cho, Byoung-Ki

    2014-08-21

    In this paper, we report a C3-symmetric liquid crystal (LC) with sixfold alkyl peripheries exhibiting an unusual smectic E-like organization in the LC state. Based on conformational considerations, the smectic assembly is attributed to the formation of an endo-type Y conformer of asymmetric triazolyl and benzylic groups that cannot be accessed in other C3-symmetric molecules exclusively showing columnar assemblies. The Y conformers form a two-dimensional oblique lattice in the aromatic layers of the ordered smectic phase. In addition, the Y-shaped molecule in the smectic phases can change into a circular shape by the 1 : 1 hydrogen-bonding interaction with a gallic acid derivative, which leads to a hexagonal columnar LC phase. The triazole-based LC design concept proves the smectic LC assembly in the C3-symmetric system, and provides the supramolecular manipulation of LC morphologies.

  7. Knitting aromatic polymers for efficient solid-phase microextraction of trace organic pollutants.

    Science.gov (United States)

    Liu, Shuqin; Hu, Qingkun; Zheng, Juan; Xie, Lijun; Wei, Songbo; Jiang, Ruifen; Zhu, Fang; Liu, Yuan; Ouyang, Gangfeng

    2016-06-10

    A series of knitting aromatic polymers (KAPs) were successfully synthesized using a simple one-step Friedel-Crafts alkylation of aromatic monomers and were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then, as-synthesized KAPs with large surface areas, unique pore structures and high thermal stability were prepared as solid-phase microextraction (SPME) coatings that exhibited good extraction abilities for a series of benzene compounds (i.e., benzene, toluene, ethylbenzene and m-xylene, which are referred to as BTEX) and polycyclic aromatic hydrocarbons (PAHs). Under the optimized conditions, the methodologies established for the determination of BTEX and PAHs using the KAPs-triPB and KAPs-B coatings, respectively, possessed wide linear ranges, low limits of detection (LODs, 0.10-1.13ngL(-1) for BTEX and 0.05-0.49ngL(-1) for PAHs) and good reproducibility. Finally, the proposed methods were successfully applied to the determination of BTEX and PAHs in environmental water samples, and satisfactory recoveries (93.6-124.2% for BTEX and 77.2-113.3% for PAHs) were achieved. This study provides a benchmark for exploiting novel microporous organic polymers (MOPs) for SPME applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Depolymerization of coal by oxidation and alkylation; Sanka bunkai to alkyl ka ni yoru sekitan kaijugo

    Energy Technology Data Exchange (ETDEWEB)

    Tomita, H.; Isoda, T.; Kusakabe, K.; Morooka, S. [Kyushu University, Fukuoka (Japan). Faculty of Engineering; Hayashi, J. [Hokkaido University, Sapporo (Japan). Center for Advanced Research of Energy Technology

    1996-10-28

    Change in depolymerization degree and coal structure was studied for depolymerization treatment of coal in various alcohol containing aqueous hydrogen peroxide. In experiment, the mixture of Yallourn coal, alcohol and aqueous hydrogen peroxide was agitated in nitrogen atmosphere of normal pressure at 70{degree}C for 12 hours. As the experimental result, the methanol solubility of only 5% of raw coal increased up to 35.2% by hydrogen peroxide treatment, while the yield of insoluble matters also decreased from 94% to 62%. Most of the gas produced during treatment was composed of inorganic gases such as CO and CO2, and its carbon loss was extremely decreased by adding alcohol. From the analytical result of carbon loss in hydrogen peroxide treatment, it was clarified that alkylation advances with introduction of alkyl group derived from alcohol into coal by hydrogen peroxide treatment under a coexistence of alcohol, and depolymerization reaction of coal itself is thus promoted by alcohol. 4 refs., 7 figs., 1 tab.

  9. Aromaticity of distorted benzene rings: exploring the validity of different indicators of aromaticity.

    Science.gov (United States)

    Feixas, Ferran; Matito, Eduard; Poater, Jordi; Solà, Miquel

    2007-05-24

    The effect of three in-plane (bond length alternation, bond length elongation, and clamping) and three out-of-plane deformations (boatlike, chairlike, and pyramidalization) on the aromaticity of the benzene molecule has been analyzed employing seven widely used indicators of aromaticity. It is shown that only the aromatic fluctuation index (FLU) is able to indicate the expected loss of aromaticity because of distortion from the equilibrium geometry in all deformations analyzed. As FLU has been shown previously to fail in other particular situations, we conclude that there is not yet a single indicator of aromaticity that works properly for all cases. Therefore, to reach safer conclusions, aromaticity analyses should be carried out employing a set of aromaticity descriptors on the basis of different physical manifestations of aromaticity.

  10. AROMATIC AND POLYCYCLIC AROMATIC HYDROCARBON FORMATION IN A LAMINAR PREMIXED N-BUTANE FLAME. (R825412)

    Science.gov (United States)

    AbstractExperimental and detailed chemical kinetic modeling work has been performed to investigate aromatic and polycyclic aromatic hydrocarbon (PAH) formation pathways in a premixed, rich, sooting, n-butane¯oxygen¯argon burner s...

  11. Substrate specific hydrolysis of aromatic and aromatic-aliphatic esters in orchid tissue cultures

    Directory of Open Access Journals (Sweden)

    Agnieszka Mironowicz

    2014-01-01

    Full Text Available We found that tissue cultures of higher plants were able, similarly as microorganisms, to transform low-molecular-weight chemical compounds. In tissue cultures of orchids (Cymbidium 'Saint Pierre' and Dendrobium phalaenopsis acetates of phenols and aromatic-aliphatic alcohols were hydrolyzed, whereas methyl esters of aromatic and aromatic-aliphatic acids did not undergo this reaction. Acetates of racemic aromatic-aliphatic alcohols were hydrolyzed with distinct enantiospecificity.

  12. Early Transition Metal Alkyl and Tetrahydroborate Complexes.

    Science.gov (United States)

    Jensen, James Allen

    1988-06-01

    An investigation of early transition metal alkyl and tetrahydroborate complexes as catalytic models and ceramic precursors has been initiated. The compounds MX _2 (dmpe)_2, dmpe = 1,2-bis(dimethylphosphino)ethane, for M = Ti, V, Cr, and X = Br, I, BH_4, have been prepared. These complexes are paramagnetic and have been shown by X-ray crystallography to have trans-octahedral structures. The BH_4^{-} groups in Ti(BH_4)_2(dmpe) _2 bond to the metal in a bidentate manner. This structure is in marked contrast to the structure of the vanadium analogue, V(BH_4)_2 (dmpe)_2, which displays two unidentate BH_4^{-} groups. Alkylation of Ti(BH_4)_2 (dmpe)_2 with LiMe results in the complex TiMe_2(dmpe) _2 which is diamagnetic in both solution and solid state. Single crystal X-ray and neutron diffraction studies show that there may be strong Ti-C pi -bonding. A tetragonal compression along the C -Ti-C bond vector accounts for the observed diamegnetism. A series of complexes of the formula Ti(BH _4)_3(PR_3)_2 has been prepared where PR_3 = PMe_3, PEt_3, PMe_3Ph, and P(OMe)_3 . The X-ray crystal structure of Ti(BH _4)_3(PMe_3)_2 reveals a pseudo trigonal bipyramidal geometry in which two BH_4^{-} groups display an unusual "side-on" bonding mode. The "side-on" ligation mode has been attributed to a Jahn-Teller distortion of the orbitally degenerate d^1 ground state. In contrast, the non-Jahn-Teller susceptible vanadium analogue, V(BH_4)_3 (PMe_3)_2, possesses a nearly ideal D_{rm 3h} >=ometry with three bidentate tetrahydroborate groups. Addition of excess PMe_3 to V(BH_4)_3(PMe _3)_2water forms the vanadium(III) oxo dimer (V(BH_4)_2 (PMe_3)_2]_2 [mu-O) which has been structurally characterized. The compound Ti(CH_2CMe _3)_4 can be prepared by addition of Ti(OEt)_4 to LiCH_2 CMe_3. Sublimation of Ti(CH _2CMe_3)_4 over a substrate heated to 250^ circC results in the chemical vapor deposition of amorphous TiC thin films. This CVD approach has been extended to the Group 4 borides: Ti

  13. Quantum transport through aromatic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda, J. H., E-mail: judith.ojeda@uptc.edu.co [Instituto de Alta investigación, Universidad de Tarapaca, Casilla 7D Arica (Chile); Grupo de Física de Materiales, Escuela de Física, Universidad Pedagógica y Tecnológica de Colombia, Tunja (Colombia); Rey-González, R. R. [Departamento de Física, Universidad Nacional de Colombia, Bogotá D. C. (Colombia); Laroze, D. [Instituto de Alta investigación, Universidad de Tarapaca, Casilla 7D Arica (Chile)

    2013-12-07

    In this paper, we study the electronic transport properties through aromatic molecules connected to two semi-infinite leads. The molecules are in different geometrical configurations including arrays. Using a nearest neighbor tight-binding approach, the transport properties are analyzed into a Green's function technique within a real-space renormalization scheme. We calculate the transmission probability and the Current-Voltage characteristics as a function of a molecule-leads coupling parameter. Our results show different transport regimes for these systems, exhibiting metal-semiconductor-insulator transitions and the possibility to employ them in molecular devices.

  14. SERIES: Genomic instability in cancer Balancing repair and tolerance of DNA damage caused by alkylating agents

    Science.gov (United States)

    Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D

    2013-01-01

    Alkylating agents comprise a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER), and mismatch repair (MMR) respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for an organism's favorable response to alkylating agents. Furthermore, an individual's response to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity. PMID:22237395

  15. Effect of Amphiphilic Alkyl Chain Length Upon Purified LATEX Stability

    International Nuclear Information System (INIS)

    Amira Amir Hassan; Amir Hashim Mohd Yatim

    2015-01-01

    Rubber particles in purified latex (PL) are stabilized by a film of protein and fatty acid soap (surfactant). Saturated straight-chain fatty acid soaps can assist an enhancement of latex stability. However, whether the alkyl chain length plays an important role in increasing the stability is still an issue. The aim of this study is to investigate the effect of alkyl chain length of anionic surfactant on the stability of purified latex. The fatty acid soap of decanoate (9), laurate (11), sodium dodecyl sulphate (SDS) (12) and palmitate (15) were used. The numbers in parentheses indicating the number of carbon present in alkyl chain of the soap. The results showed that the impact of alkyl chain length on the stability of latex is in the order of laurate > decanoate > SDS > palmitate > purified latex accordingly. The alkyl chain length does giving a significant effect on latex stability after longer stirring time. The particle size of latex with the presence of surfactant is greater compare to a single particle itself due to extension of particles diameter. Thus suitable interaction of the nonpolar tail of surfactant with the hydrophobic regions of latex surface played a major role in maintaining a stable latex system. (author)

  16. Effect of curcumin on the genotoxicity induced by alkylating agents

    Directory of Open Access Journals (Sweden)

    İbrahim Hakkı Ciğerci

    2015-06-01

    Full Text Available The protection of the structure of DNA is extremly important to transfer genetic information from generation to generation. DNA damage due to genotoxic ess is an important type of stress which organisms are exposed during their life. The factors that cause DNA damage can be endogenous and exogenous. Among exogenous sources, alkylating agents comes first to cause DNA damage. Alkylating exogenous agents are capable of adding bases to ethyl or methyl groups. The direct-acting alkylating agent methyl methanesulfonate (MMS, is covalently linked to DNA and cause DNA damage, creating an indirect effect of the alkylating agent. cyclophosphamide (CP causes the DNA damage by changing the function of cellular proteins. Both substances have been shown to induce gene mutations in prokaryotes and eukaryotes, chromosome effects, unscheduled DNA synthesis and sister chromatid exchange. Furthermore, cessation of cell growth arrest and DNA damage causing changes in gene expression have been observed by the stress due to alkylating agents exposure. In this study, the effects of curcumin on MMS and CP treated mice were investigated. Alkaline comet assay was used to detect DNA damage. Curcumin reduced the DNA damage, occurred by both MMS and CP induction. We could state that curcumin, a phenolic compound shows protective effects before the damage. In brief, curcumin has both antioxidant and antigenotoxic effects.

  17. Birds and polycyclic aromatic hydrocarbons

    Science.gov (United States)

    Albers, P.H.

    2006-01-01

    Polycyclic aromatic hydrocarbons (PAH) are present throughout the global environment and are produced naturally and by activities of humans. Effects of PAH on birds have been determined by studies employing egg injection, egg immersion, egg shell application, single and multiple oral doses, subcutaneous injection, and chemical analysis of field-collected eggs and tissue. The four-to six-ring aromatic compounds are the most toxic to embryos, young birds, and adult birds. For embryos, effects include death, developmental abnormalities, and a variety of cellular and biochemical responses. For adult and young birds, effects include reduced egg production and hatching, increased clutch or brood abandonment, reduced growth, increased organweights, and a variety of biochemical responses. Trophic level accumulation is unlikely. Environmental exposure to PAH in areas of high human population or habitats affected by recent petroleum spills might be sufficient to adversely affect reproduction. Evidence of long-term effects of elevated concentrations of environmental PAH on bird populations is very limited and the mechanisms of effect are unclear.

  18. Theoretical studies of the structures and local aromaticity of conjugated polycyclic hydrocarbons using three aromatic indices

    Science.gov (United States)

    Sakai, Shogo; Kita, Yuki

    2013-07-01

    The structures and local aromaticity of some conjugated polycyclic hydrocarbons (from the butadienoid, acene, and phenylene series) are studied using ab initio MO and density functional methods. The aromaticities of the molecules are estimated using three indices: the nucleus-independent chemical shift (NICS), the harmonic oscillator model of aromaticity (HOMA), and the index of deviation from aromaticity (IDA). Assessment of the relationships between the structures and the aromatic indices shows that the IDA values correspond best to the characteristics of the conjugated polycyclic hydrocarbon structures.

  19. Effects of methyl group on aromatic hydrocarbons on the nanostructures and oxidative reactivity of combustion-generated soot

    KAUST Repository

    Guerrero Peña, Gerardo D.J.

    2016-07-23

    The substituted and unsubstituted aromatic hydrocarbons, present in transportation fuels such as gasoline and diesel, are thought to be responsible for most of the soot particles produced during their combustion. However, the effects of the substituted alkyl groups on the aromatic hydrocarbons on their sooting tendencies, and on the physical and chemical properties of soot produced from them are not well understood. In this work, the effect of the presence of methyl groups on aromatic hydrocarbons on their sooting propensity, and on the oxidative reactivity, morphology, and chemical composition of soot generated from them in diffusion flames is studied using benzene, toluene, and m-xylene as fuels. Several experimental techniques including high resolution transmission electron microscopy and X-ray diffraction are used to identify the morphological changes in soot, whereas the elemental and thermo-gravimetric analyses, electron energy loss spectroscopy, and Fourier transform infrared spectroscopy are used to study the changes in its chemical properties and reactivity. The activation energies for soot oxidation are calculated at different conversion levels, and a trend in the reactivity of soots from benzene, toluene and m-xylene is reported. It is observed that the sizes of primary particles and graphene-like sheets, and the concentrations of aliphatics and oxygenated groups in soot particles decreased with the addition of methyl group(s) on the aromatic ring. The physicochemical changes in soot are found to support the oxidative reactivity trends. © 2016 The Combustion Institute

  20. Composition and source diagnostics of polycyclic aromatic ...

    African Journals Online (AJOL)

    Composition and source diagnostics of polycyclic aromatic hydrocarbons in sediments from Elelenwo Creek, southern Nigeria. I Agbozu, K Opuene, O Benson. Abstract. The survey of polycyclic aromatic hydrocarbons (PAHs) and their relation to potential pollution sources was carried out in sediments from Elelenwo Creek, ...

  1. Aromatic saturation of distillates. An overview

    International Nuclear Information System (INIS)

    Cooper, Barry H.; Donnis, Bjoern B.L.

    1996-01-01

    The saturation of aromatic compounds in distillate fractions and in particular in diesel fuel has received considerable attention in recent years. A high aromatic content is associated with poor fuel quality, giving a low cetane number in diesel fuel and a high smoke point in jet fuel. There is also evidence that particulate emissions in diesel exhaust gases correlate with the aromatic content of the fuel. New legislation has been introduced to limit aromatics in diesel fuel and this has led to new catalyst and process developments for aromatic saturation. This paper gives an overview of these developments. The types of aromatic compounds found in distillate streams are described, and the kinetics of both single (model) compounds and groups of compounds as found in industrial feedstocks are discussed. Both supported metal sulfide and supported noble metal catalysts are used industrially and the paper outlines the role of the active species in these catalysts and compares reaction conditions used for each. The tolerance of different catalyst systems towards sulfur and nitrogen in the feed is dealt with in some detail. Commercial processes employ either single- or dual-stage catalyst systems depending on the nature of the aromatic saturation catalyst. The paper considers the merits of different process configurations. The paper concludes with a brief survey of possible future applications for distillate aromatic saturation catalysts

  2. Quantifying aromaticity with electron delocalisation measures.

    Science.gov (United States)

    Feixas, Ferran; Matito, Eduard; Poater, Jordi; Solà, Miquel

    2015-09-21

    Aromaticity cannot be measured directly by any physical or chemical experiment because it is not a well-defined magnitude. Its quantification is done indirectly from the measure of different properties that are usually found in aromatic compounds such as bond length equalisation, energetic stabilisation, and particular magnetic behaviour associated with induced ring currents. These properties have been used to set up the myriad of structural-, energetic-, and magnetic-based indices of aromaticity known to date. The cyclic delocalisation of mobile electrons in two or three dimensions is probably one of the key aspects that characterise aromatic compounds. However, it has not been until the last decade that electron delocalisation measures have been widely employed to quantify aromaticity. Some of these new indicators of aromaticity such as the PDI, FLU, ING, and INB were defined in our group. In this paper, we review the different existing descriptors of aromaticity that are based on electron delocalisation properties, we compare their performance with indices based on other properties, and we summarise a number of applications of electronic-based indices for the analysis of aromaticity in interesting chemical problems.

  3. Alkylation of imidazole under ultrasound irradiation over alkaline carbons

    Energy Technology Data Exchange (ETDEWEB)

    Costarrosa, L. [Dpto. de Quimica Inorganica y Quimica Tecnica, Facultad de Ciencias, Universidad Nacional de Educacion a Distancia (UNED), C/Senda del Rey, 9, E-28040 Madrid (Spain); Calvino-Casilda, V. [Dpto. de Quimica Inorganica y Quimica Tecnica, Facultad de Ciencias, Universidad Nacional de Educacion a Distancia (UNED), C/Senda del Rey, 9, E-28040 Madrid (Spain); Ferrera-Escudero, S. [Dpto. de Quimica Inorganica y Quimica Tecnica, Facultad de Ciencias, Universidad Nacional de Educacion a Distancia (UNED), C/Senda del Rey, 9, E-28040 Madrid (Spain); Duran-Valle, C.J. [Dpto. de Quimica Inorganica, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s/n, 06071 Badajoz (Spain); Martin-Aranda, R.M. [Dpto. de Quimica Inorganica y Quimica Tecnica, Facultad de Ciencias, Universidad Nacional de Educacion a Distancia (UNED), C/Senda del Rey, 9, E-28040 Madrid (Spain)]. E-mail: rmartin@ccia.uned.es

    2006-06-30

    N-Alkyl-imidazole has been synthesized by sonochemical irradiation of imidazole and 1-bromobutane using alkaline-promoted carbons (exchanged with the binary combinations of Na, K and Cs). The catalysts were characterized by X-ray photoelectron spectroscopy, thermal analysis and N{sub 2} adsorption isotherms. Under the experimental conditions, N-alkyl-imidazoles can be prepared with a high activity and selectivity. It is observed that imidazole conversion increases in parallel with increasing the basicity of the catalyst. The influence of the alkaline promoter, the reaction temperature, and the amount of catalyst on the catalytic activity has been studied. For comparison, the alkylation of imidazole has also been performed in a batch reactor system under thermal activation.

  4. Safety Assessment of Alkyl Ethylhexanoates as Used in Cosmetics.

    Science.gov (United States)

    Fiume, Monice; Heldreth, Bart; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2015-01-01

    The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) assessed the safety of 16 alkyl ethylhexanoates for use in cosmetics, concluding that these ingredients are safe in cosmetic formulations in the present practices of use and concentrations when formulated to be nonirritating. The alkyl ethylhexanoates primarily function as skin-conditioning agents in cosmetics. The highest concentration of use reported for any of the alkyl ethylhexanoates is 77.3% cetyl ethylhexanoate in rinse-off formulations used near the eye, and the highest leave-on use reported is 52% cetyl ethylhexanoate in lipstick formulations. The Panel reviewed available animal and clinical data related to these ingredients, and the similarities in structure, properties, functions, and uses of ingredients from previous CIR assessments on constituent alcohols that allowed for extrapolation of the available toxicological data to assess the safety of the entire group. © The Author(s) 2015.

  5. Safety Assessment of Alkyl PEG Sulfosuccinates as Used in Cosmetics.

    Science.gov (United States)

    Johnson, Wilbur; Heldreth, Bart; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2015-09-01

    The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) reviewed the safety of alkyl polyethylene glycol (PEG) sulfosuccinates, which function in cosmetics mostly as surfactants/cleansing agents. Although these ingredients may cause ocular and skin irritation, dermal penetration is unlikely because of the substantial polarity and molecular size of these ingredients. The Panel considered the negative oral carcinogenicity and reproductive and developmental toxicity data on chemically related laureths (PEG lauryl ethers) and negative repeated dose toxicity and skin sensitization data on disodium laureth sulfosuccinate supported the safety of these alkyl PEG sulfosuccinates in cosmetic products, but. The CIR Expert Panel concluded that the alkyl PEG sulfosuccinates are safe in the present practices of use and concentration when formulated to be nonirritating. © The Author(s) 2015.

  6. Radiation-chemical alkylation of olefines with adamantane

    International Nuclear Information System (INIS)

    Podkhalyuzin, A.T.; Vikulin, V.V.; Morozov, V.A.; Nazarova, M.P.; Vereshchinskii, I.V.

    1977-01-01

    Radiation-chemical alkylation of C 2 to C 4 olefines with adamantane was studied in gas phase at temperatures 270 to 430 0 C. The main reaction product is monoalkyladamantane. The reaction proceeds by a free radical chain mechanism. The effective activation energy is of the order of 8 to 10 kcal/mole. Thermal alkylation was carried out for comparison and the contribution of the thermal component to the radiation-thermal process was estimated. Liquid phase alkylation of hexafluoropropylene with adamantane was studied in the presence of solvents. Under various conditions mono- and di-substituted adamantanes are produced containing fluorine in end groups. These compounds were converted to corresponding fluoroalkenyladamantanes by dehydrofluorination. The kinetic parameters were calculated and physical-chemical data concerning some of the resulting products were determined. (author)

  7. From old alkylating agents to new minor groove binders.

    Science.gov (United States)

    Puyo, Stéphane; Montaudon, Danièle; Pourquier, Philippe

    2014-01-01

    Alkylating agents represent the oldest class of anticancer agents with the approval of mechloretamine by the FDA in 1949. Even though their clinical use is far beyond the use of new targeted therapies, they still occupy a major place in the treatment of specific malignancies, sometimes representing the unique option for the treatment of refractory tumors. Here, we are reviewing the major classes of alkylating agents, with a particular focus on the latest generations of compounds that specifically target the minor groove of the DNA. These naturally occurring derivatives have a unique mechanism of action that explains the recent regain of interest in developing new classes of alkylating agents that could be used in combination with other anticancer drugs to enhance tumor response in the clinic. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Alkylation of imidazole under ultrasound irradiation over alkaline carbons

    International Nuclear Information System (INIS)

    Costarrosa, L.; Calvino-Casilda, V.; Ferrera-Escudero, S.; Duran-Valle, C.J.; Martin-Aranda, R.M.

    2006-01-01

    N-Alkyl-imidazole has been synthesized by sonochemical irradiation of imidazole and 1-bromobutane using alkaline-promoted carbons (exchanged with the binary combinations of Na, K and Cs). The catalysts were characterized by X-ray photoelectron spectroscopy, thermal analysis and N 2 adsorption isotherms. Under the experimental conditions, N-alkyl-imidazoles can be prepared with a high activity and selectivity. It is observed that imidazole conversion increases in parallel with increasing the basicity of the catalyst. The influence of the alkaline promoter, the reaction temperature, and the amount of catalyst on the catalytic activity has been studied. For comparison, the alkylation of imidazole has also been performed in a batch reactor system under thermal activation

  9. Selective mono-alkylation of N-methoxybenzamides.

    Science.gov (United States)

    Chen, Zenghua; Hu, Le'an; Zeng, Fanyun; Zhu, Ranran; Zheng, Shasha; Yu, Qingzhen; Huang, Jianhui

    2017-04-11

    We report our latest discovery of norbornene derivative modulated highly mono-selective ortho-C-H activation alkylation reactions on arenes bearing simple mono-dentate coordinating groups. The reaction features the use of readily available benzamides and alkyl halides. During the study, we prepared 30 mono-alkylated aryl amides in good yields with good mono-selectivity. We have also demonstrated that structurally rigid alkenes such as norbornene and its derivatives are a good class of ligand and could be used for future direct C-H functionalizations. The utilization of norbornene type ligands for assistance in C-H activation processes has opened a new window for future molecular design using direct C-H functionalization strategies.

  10. Syntheses and evaluation of anticonvulsant activity of novel branched alkyl carbamates.

    Science.gov (United States)

    Hen, Naama; Bialer, Meir; Yagen, Boris

    2012-03-22

    A novel class of 19 carbamates was synthesized, and their anticonvulsant activity was comparatively evaluated in the rat maximal electroshock (MES) and subcutaneous metrazol (scMet) seizure tests and pilocarpine-induced status epilepticus (SE) model. In spite of the alkyl-carbamates' close structural features, only compounds 34, 38, and 40 were active at the MES test. The analogues 2-ethyl-3-methyl-butyl-carbamate (34) and 2-ethyl-3-methyl-pentyl-carbamate (38) also exhibited potent activity in the pilocarpine-SE model 30 min postseizure onset. Extending the aliphatic side chains of homologous carbamates from 7 to 8 (34 to 35) and from 8 to 9 carbons in the homologues 38 and 43 decreased the activity in the pilocarpine-SE model from ED(50) = 81 mg/kg (34) to 94 mg/kg (35) and from 96 mg/kg (38) to 114 mg/kg (43), respectively. The most potent carbamate, phenyl-ethyl-carbamate (47) (MES ED(50) = 16 mg/kg) contains an aromatic moiety in its structure. Compounds 34, 38, 40, and 47 offer the optimal efficacy-safety profile and, consequently, are promising candidates for development as new antiepileptics.

  11. Chiral alkylated-aniline as a noninvasive fluorescence sensor: Spectroscopic and molecular modeling studies

    Science.gov (United States)

    Sengupta, Bidisha; Mukherjee, Chirantan Sen; Chakraborty, Sandipan; Muhammad, Maria Jones; Gladney, William; Armstrong, George

    2017-12-01

    Aniline, heterocyclic aromatic amines, and arylamines are known carcinogens. Recently aniline mustard has come into prominence as a novel anticancer agent. In this project, microwave irradiation has been used to synthesize an optically active alkylated aniline namely 2,6-dimethyl-4-(1-(p-tolyl)ethyl)aniline (abbreviated DMPA). The presence of quartet and doublet peaks in NMR and a single chromatogram in HPLC verified that the final product DMPA, prepared from the synthesis reactions, had no major impurities. By using a Lux chiral column in HPLC, two peaks have been detected in the chromatogram, which correspond to two enantiomers of the chiral aniline derivative. Fluorescence spectroscopic measurements on DMPA indicated conspicuous dependence of its emission behavior on the polarity (in terms of the empirical polarity parameter ET(30)) of the homogeneous solvents used, a property important for an optical sensor. The nature of the emission profiles, along with the relevant parameter namely wavelength at emission maximum (λemmax) is used to infer the distribution, binding and microenvironment of the DMPA molecules in human serum albumin protein (HSA). DMPA is weakly fluorescent in aqueous buffer medium, with a dramatic enhancement in the fluorescence emission in the presence of HSA. Molecular modeling studies have been carried out on the two enantiomers (R and S) of DMPA with HSA. The implications of these findings are examined in relation to the potentialities of DMPA as a novel fluorescence sensor for biological systems.

  12. Alkylation sensitivity screens reveal a conserved cross-species functionome

    Science.gov (United States)

    Svilar, David; Dyavaiah, Madhu; Brown, Ashley R.; Tang, Jiang-bo; Li, Jianfeng; McDonald, Peter R.; Shun, Tong Ying; Braganza, Andrea; Wang, Xiao-hong; Maniar, Salony; St Croix, Claudette M.; Lazo, John S.; Pollack, Ian F.; Begley, Thomas J.; Sobol, Robert W.

    2013-01-01

    To identify genes that contribute to chemotherapy resistance in glioblastoma, we conducted a synthetic lethal screen in a chemotherapy-resistant glioblastoma derived cell line with the clinical alkylator temozolomide (TMZ) and an siRNA library tailored towards “druggable” targets. Select DNA repair genes in the screen were validated independently, confirming the DNA glycosylases UNG and MYH as well as MPG to be involved in the response to high dose TMZ. The involvement of UNG and MYH is likely the result of a TMZ-induced burst of reactive oxygen species. We then compared the human TMZ sensitizing genes identified in our screen with those previously identified from alkylator screens conducted in E. coli and S. cerevisiae. The conserved biological processes across all three species composes an Alkylation Functionome that includes many novel proteins not previously thought to impact alkylator resistance. This high-throughput screen, validation and cross-species analysis was then followed by a mechanistic analysis of two essential nodes: base excision repair (BER) DNA glycosylases (UNG, human and mag1, S. cerevisiae) and protein modification systems, including UBE3B and ICMT in human cells or pby1, lip22, stp22 and aim22 in S. cerevisiae. The conserved processes of BER and protein modification were dual targeted and yielded additive sensitization to alkylators in S. cerevisiae. In contrast, dual targeting of BER and protein modification genes in human cells did not increase sensitivity, suggesting an epistatic relationship. Importantly, these studies provide potential new targets to overcome alkylating agent resistance. PMID:23038810

  13. Differential alkylation-based redox proteomics - Lessons learnt

    DEFF Research Database (Denmark)

    Wojdyla, Katarzyna; Rogowska-Wrzesinska, Adelina

    2015-01-01

    -sulfenylation are crucial mediators of intracellular redox signalling, with known associations to health and disease. Study of their functionalities has intensified thanks to the development of various analytical strategies, with particular contribution from differential alkylation-based proteomics methods. Presented here...... is a critical evaluation of differential alkylation-based strategies for the analysis of S-nitrosylation and S-sulfenylation. The aim is to assess the current status and to provide insights for future directions in the dynamically evolving field of redox proteomics. To achieve that we collected 35 original...

  14. Solid-Phase S-Alkylation Promoted by Molecular Sieves.

    Science.gov (United States)

    Calce, Enrica; Leone, Marilisa; Mercurio, Flavia Anna; Monfregola, Luca; De Luca, Stefania

    2015-11-20

    A solid-phase S-alkylation procedure to introduce chemical modification on the cysteine sulfhydryl group of a peptidyl resin is reported. The reaction is promoted by activated molecular sieves and consists of a solid-solid process, since both the catalyst and the substrate are in a solid state. The procedure was revealed to be efficient and versatile, particularly when used in combination with the solution S-alkylation approach, allowing for the introduction of different molecular diversities on the same peptide molecule.

  15. The effect of alkylating agents on model supported metal clusters

    Energy Technology Data Exchange (ETDEWEB)

    Erdem-Senatalar, A.; Blackmond, D.G.; Wender, I. (Pittsburgh Univ., PA (USA). Dept. of Chemical and Petroleum Engineering); Oukaci, R. (CERHYD, Algiers (Algeria))

    1988-01-01

    Interactions between model supported metal clusters and alkylating agents were studied in an effort to understand a novel chemical trapping technique developed for identifying species adsorbed on catalyst surfaces. It was found that these interactions are more complex than had previously been suggested. Studies were completed using deuterium-labeled dimethyl sulfate (DMS), (CH{sub 3}){sub 2}SO{sub 4}, as a trapping agent to interact with the supported metal cluster ethylidyne tricobalt enneacarbonyl. Results showed that oxygenated products formed during the trapping reaction contained {minus}OCD{sub 3} groups from the DMS, indicating that the interaction was not a simple alkylation. 18 refs., 1 fig., 3 tabs.

  16. Synthesis and Characterization of 5-(hydrazino-alkyl) Tetrazoles

    Science.gov (United States)

    2014-07-01

    structure and 1H NMR spectrum of hydrazone 7 7 Synthesis of 5 - (hydrazino - alkyl) tetrazole via BOC hydrazine Amino acid- BOC Amino acid . HCl...Acidic medium Tetrazole-R-N2H2- BOC Acidic medium Tetrazole-R-N2H2 . HCl  Address solubility issues  Solid state structures of hydrochloride salt...hydrazino - alkyl) tetrazole via BOC hydrazine Removal of BOC protecting group 11, n = 1 12, n = 2 1H NMR and DSC of 5-(hydrazino-methyl)tetrazole

  17. Regeneration of zeolite catalysts of isobutane alkylation with butenes

    Energy Technology Data Exchange (ETDEWEB)

    Manza, I.A.; Tsupryk, I.N.; Bartyshevskii, V.A.; Gaponenko, O.I.; Petrilyak, K.I.

    1986-12-10

    The industrial adoption of alkylation of isoalkanes with alkenes is held back by the rapid and irreversible deactivation of the zeolite catalysts appropriate to the process. This paper is aimed specifically at the restoration of the catalytic activity and increase in the service life of zeolite alkylation catalysts. The catalyst chosen for the investigation was HLaCaNaX zeolite both unmodified and modified with various multivalence cations. The thermochemical and oxidative regeneration process as well as the equipment utilized are described. Both the advantages and the drawbacks of the method are given; explanations for the possibly irreversible losses of the catalytic properties in the regenerated zeolites are also put forward.

  18. Experimental studies on toxicity of ethylene glycol alkyl ethers in Japan.

    OpenAIRE

    Nagano, K; Nakayama, E; Oobayashi, H; Nishizawa, T; Okuda, H; Yamazaki, K

    1984-01-01

    Past studies on the toxicological effects of ethylene glycol alkyl ethers as well as the recent data on these chemicals in Japan are reviewed. Only a few researchers have participated in the study of ethylene glycol alkyl ethers in Japan. The effects of ethylene glycol alkyl ethers on testis and embryotoxic effects of ethylene glycol monomethyl ether (EGM) have been studied, as has the teratogenicity of ethylene glycol dimethyl ether (EGdM). Studies on ethylene glycol alkyl ethers and related...

  19. The toxicity of photomodified polycyclic aromatic hydrocarbons to Japanese medaka (Oryzias latipes) embryos

    Energy Technology Data Exchange (ETDEWEB)

    Farwell, A.J.; Croft, M.; Rhodes, S.M.; Dixon, D.G. [Waterloo Univ., ON (Canada). Dept. of Biology

    2003-07-01

    Alkylated polycyclic aromatic hydrocarbons (PAHs) occur naturally in process-affected waters associated with bitumen extraction from the Athabasca oil sands in northern Alberta. The hydrocarbon fraction of process-affected water increases the frequency and severity of blue sac disease in Japanese medaka. It also reduces the larval fork length. The United States Environmental Protection Agency has determined that the most common hydrocarbon fraction of the priority pollutants is C2-substituted dibenzothiophenes. This extract was exposed to simulated solar radiation (SSR) to determine the effects of photomodification on its toxicity. Japanese medaka embryos exposed to SSR extracts for 1 and 4 days showed decreased toxicity compared to non-photomodified extracts. Four-day exposures did not reveal any significant changes in hatch length or blue sac disease symptoms, but there was a slight increase in time to hatch.

  20. Formation of aromatics in thermally induced reactions of chemically bonded RP-C18 stationary phase.

    Science.gov (United States)

    Prus, Wojciech

    2014-10-01

    In continuation of the research on the thermally induced chemical transformation of the silica-based chemically bonded stationary phases (C18), the oxidative cleavage of the silicon-carbon bonds with hydrogen peroxide and potassium fluoride was utilized, followed by the gas chromatography coupled with mass spectrometry (GC-MS) study of the resulting products. These investigations allowed determination of the probable structures of certain thermal modification products as the various different alkyl derivatives of the phenylsilane ligands. Apart from aromatic compounds, the products with unsaturated bonds and carbonyl functionalities were found in the analyzed extracts. The analysis of the GC-MS chromatograms reveals that under the applied working conditions, the investigated process runs with relatively low yields. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Immobilization of Lipases on Alkyl Silane Modified Magnetic Nanoparticles: Effect of Alkyl Chain Length on Enzyme Activity

    Science.gov (United States)

    Wang, Jiqian; Meng, Gang; Tao, Kai; Feng, Min; Zhao, Xiubo; Li, Zhen; Xu, Hai; Xia, Daohong; Lu, Jian R.

    2012-01-01

    Background Biocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification. Methodology/Principal Findings Magnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18) modified Fe3O4 were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining. Conclusions/Significance The activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for enzyme immobilization

  2. Immobilization of lipases on alkyl silane modified magnetic nanoparticles: effect of alkyl chain length on enzyme activity.

    Directory of Open Access Journals (Sweden)

    Jiqian Wang

    Full Text Available BACKGROUND: Biocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification. METHODOLOGY/PRINCIPAL FINDINGS: Magnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18 modified Fe(3O(4 were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining. CONCLUSIONS/SIGNIFICANCE: The activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for

  3. Immobilization of lipases on alkyl silane modified magnetic nanoparticles: effect of alkyl chain length on enzyme activity.

    Science.gov (United States)

    Wang, Jiqian; Meng, Gang; Tao, Kai; Feng, Min; Zhao, Xiubo; Li, Zhen; Xu, Hai; Xia, Daohong; Lu, Jian R

    2012-01-01

    Biocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification. Magnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18) modified Fe(3)O(4) were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining. The activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for enzyme immobilization enabling efficient enzyme recovery and recycling.

  4. Sources of sedimentary PAHs in tropical Asian waters: differentiation between pyrogenic and petrogenic sources by alkyl homolog abundance.

    Science.gov (United States)

    Saha, Mahua; Togo, Ayako; Mizukawa, Kaoruko; Murakami, Michio; Takada, Hideshige; Zakaria, Mohamad P; Chiem, Nguyen H; Tuyen, Bui Cach; Prudente, Maricar; Boonyatumanond, Ruchaya; Sarkar, Santosh Kumar; Bhattacharya, Badal; Mishra, Pravakar; Tana, Touch Seang

    2009-02-01

    We collected surface sediment samples from 174 locations in India, Indonesia, Malaysia, Thailand, Vietnam, Cambodia, Laos, and the Philippines and analyzed them for polycyclic aromatic hydrocarbons (PAHs) and hopanes. PAHs were widely distributed in the sediments, with comparatively higher concentrations in urban areas (Sigma PAHs: approximately 1000 to approximately 100,000 ng/g-dry) than in rural areas ( approximately 10 to approximately 100g-dry), indicating large sources of PAHs in urban areas. To distinguish petrogenic and pyrogenic sources of PAHs, we calculated the ratios of alkyl PAHs to parent PAHs: methylphenanthrenes to phenanthrene (MP/P), methylpyrenes+methylfluoranthenes to pyrene+fluoranthene (MPy/Py), and methylchrysenes+methylbenz[a]anthracenes to chrysene+benz[a]anthracene (MC/C). Analysis of source materials (crude oil, automobile exhaust, and coal and wood combustion products) gave thresholds of MP/P=0.4, MPy/Py=0.5, and MC/C=1.0 for exclusive combustion origin. All the combustion product samples had the ratios of alkyl PAHs to parent PAHs below these threshold values. Contributions of petrogenic and pyrogenic sources to the sedimentary PAHs were uneven among the homologs: the phenanthrene series had a greater petrogenic contribution, whereas the chrysene series had a greater pyrogenic contribution. All the Indian sediments showed a strong pyrogenic signature with MP/P approximately 0.5, MPy/Py approximately 0.1, and MC/C approximately 0.2, together with depletion of hopanes indicating intensive inputs of combustion products of coal and/or wood, probably due to the heavy dependence on these fuels as sources of energy. In contrast, sedimentary PAHs from all other tropical Asian cities were abundant in alkylated PAHs with MP/P approximately 1-4, MPy/Py approximately 0.3-1, and MC/C approximately 0.2-1.0, suggesting a ubiquitous input of petrogenic PAHs. Petrogenic contributions to PAH homologs varied among the countries: largest in Malaysia

  5. 40 CFR 721.520 - Alanine, N-(2-carboxyethyl)-N-alkyl-, salt.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alanine, N-(2-carboxyethyl)-N-alkyl... Specific Chemical Substances § 721.520 Alanine, N-(2-carboxyethyl)-N-alkyl-, salt. (a) Chemical substance... alanine, N-(2-carboxyethyl)-N- alkyl-, salt (P-89-336) is subject to reporting under this section for the...

  6. 40 CFR 721.5380 - Mixed alkyl phenolic novolak resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixed alkyl phenolic novolak resin... Specific Chemical Substances § 721.5380 Mixed alkyl phenolic novolak resin (generic). (a) Chemical... as mixed alkyl phenolic novolak resin (PMN P-98-718) is subject to reporting under this section for...

  7. 40 CFR 721.10143 - Amines, bis (C11-14-branched and linear alkyl).

    Science.gov (United States)

    2010-07-01

    ... linear alkyl). 721.10143 Section 721.10143 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10143 Amines, bis (C11-14-branched and linear alkyl). (a) Chemical..., bis (C11-14-branched and linear alkyl) (PMN P-06-733; CAS No. 900169-60-0) is subject to reporting...

  8. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fatty alkyl phosphate, alkali metal... Specific Chemical Substances § 721.5985 Fatty alkyl phosphate, alkali metal salt (generic). (a) Chemical... as a fatty alkyl phosphate, alkali metal salt (PMN P-99-0385) is subject to reporting under this...

  9. 40 CFR 721.2565 - Alkylated sulfonated diphenyl oxide, alkali and amine salts.

    Science.gov (United States)

    2010-07-01

    ..., alkali and amine salts. 721.2565 Section 721.2565 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.2565 Alkylated sulfonated diphenyl oxide, alkali and... substances identified as alkylated sulfonated diphenyl oxide, alkali salt (PMN P-93-352) and alkylated...

  10. Alkylation and dimerisation of 2,6-substituted phenols induced by cobalt-60 gamma radiation in hydrocarbons Part I. Alkylation

    Science.gov (United States)

    Chutný, B.; Brodilová, J.; Pospíšil, J.

    The behavior of 2, 6-substituted phenols in hydrocarbons under the influence of gamma radiation and in the absence of oxygen was studied. Thus 2-methyl-6-tert. butyl phenol in isooctane solution was alkylated in the position 4 and 2-methyl-4-/1, 1, 3, 3- tetramethylbutyl/ -6-tert. butylphenol was formed at a conversion 33%. Among the products also 3, 3-'dimethyl-5, 5-ditert. butyl-4, 4-'biphenyldiol was found. Radiation yields were calculated and some reactions of the alkylation mechanism were proposed.

  11. Influences of humic acid on the bioavailability of phenanthrene and alkyl phenanthrenes to early life stages of marine medaka (Oryzias melastigma)

    International Nuclear Information System (INIS)

    Liu, Yangzhi; Yang, Chenghu; Cheng, Pakkin; He, Xiaojing; Zhu, Yaxian; Zhang, Yong

    2016-01-01

    The influences of humic acid (HA) on the environmental behavior and bioavailability of parent polycyclic aromatic hydrocarbons (PAHs) and alkyl PAHs were investigated and compared using the early life stages of marine medaka (Oryzias melastigma, O. melastigma). It was demonstrated that the binding affinity of parent phenanthrene (PHE) with HA was smaller than that of 3-methyl phenanthrene (3-MP) and 9-ethyl phenanthrene (9-EP). Furthermore, the bioaccumulation of the three PAHs and the levels of lipid peroxidation (LPO) were calculated to study the changes in bioavailability of PAHs in presence of HA. The results indicated that the addition of HA significantly decreased the bioaccumulation and toxicity of PAHs by decreasing free PAHs concentrations. The bioavailable fractions of HA-bound PAHs in bioaccumulation (α) and toxicity (β) were evaluated, indicating that the HA-bound 3-MP and 9-EP show higher bioavailability in bioaccumulation and lower bioavailability in toxicity relative to those of PHE. The β/α values were less than 1 for all PAH treatment groups containing HA, suggesting that the fraction of HA-bound PAHs contributing to bioaccumulation was higher than that of HA-bound PAHs inducing toxic effect. In addition, we proposed that the free PAHs generated by desorption from HA in the cell were toxic by showing that the β/α ratio values are correlated with the log K OW values (p = 0.007 and R 2  = 0.8355). Thus, oil spill risk assessments should consider both alkyl PAHs and the factors that influence the bioavailability and toxicity of PAHs in the natural aquatic environments. - Highlights: • Effects of HA on bioavailability of parent and alkyl PAHs were firstly compared. • Changes in the bioavailability due to HA depended on the alkylation of PAHs. • The bioavailable fractions of the HA-bound parent and alkyl PAHs were calculated. • The toxicity of HA-bound PAHs was related to the physicochemical properties of PAHs. - This study is the

  12. The relationship between mutagenicity and chemical composition of polycyclic aromatic compounds from coal pyrolysis.

    Science.gov (United States)

    Wornat, M J; Braun, A G; Hawiger, A; Longwell, J P; Sarofim, A F

    1990-01-01

    The polycyclic aromatic compounds (PAC) produced from the pyrolysis of a bituminous coal at temperatures of 1125 to 1425 degrees K prove to be mutagenic to S. typhimurium, both in the presence and in the absence of postmitochondrial supernatant (PMS) prepared from Aroclor 1254-induced rat liver. Mutagenicity of the PAC samples measured in the absence of PMS exhibits little dependence on pyrolysis temperature; that measured in its presence is higher at the higher pyrolysis temperatures. However, because of the decrease in PAC yield as the temperature is raised, mutagenicity per mass of coal consumed falls with an increase in temperature if measured without PMS (-PMS) and peaks at an intermediate temperature of 1378 degrees K if measured with PMS (+PMS). Using a new chromatographic technique, we have split each coal-derived PAC sample into two fractions: LC1, containing PAC with alkyl and O-containing substitutions and LC2, consisting of unsubstituted PAC. Substituted (LC1) fractions show no significant +PMS mutagenicity, indicating that, as a whole, the alkylated PAC in our coal pyrolysis products are not mutagenic. Only at the higher temperatures do the substituted fractions exhibit significant -PMS mutagenicity, attributed to PAC with carbonyl or etheric functionalities. The extremely low yields of the substituted PAC under the conditions where they show some activity, however, ensure that they contribute little to overall mutagenicity. In contrast to the substituted fractions, the unsubstituted (LC2) fractions display significant mutagenicity under all conditions and appear to be responsible for virtually all of the mutagenicity in these coal-derived PAC samples. In this fraction, -PMS activity is attributed to nitrogen-containing heterocyclic aromatics. PMID:2190813

  13. Polycyclic aromatic hydrocarbons (PAHs) in ambient aerosols from Beijing: characterization of low volatile PAHs by positive-ion atmospheric pressure photoionization (APPI) coupled with Fourier transform ion cyclotron resonance.

    Science.gov (United States)

    Jiang, Bin; Liang, Yongmei; Xu, Chunming; Zhang, Jingyi; Hu, Miao; Shi, Quan

    2014-05-06

    Aromatic fractions derived from aerosol samples were characterized by gas chromatography and mass spectrometry (GC-MS), high temperature simulated distillation (SIMDIS), and positive-ion atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), respectively. It was found that about 27 wt % compounds in aromatic fractions could not be eluted from a GC column and some large molecule PAHs were neglected in GC-MS analysis. APPI FT-ICR MS was proven to be a powerful approach for characterizing the molecular composition of aromatics, especially for the large molecular species. An aromatic sample from Beijing urban aerosol was successfully characterized by APPI FT-ICR MS. Results showed that most abundant aromatic compounds in PM2.5 (particles with aerodynamic diameter ≤ 2.5 μm) were highly condensed hydrocarbons with 4-8 aromatic rings and their homologues with very short alkyl chains. Furthermore, heteroatom-containing hydrocarbons were found as the significant components of the aromatic fractions: O1, O2, N1, and S1 class species with 10-28 DBEs (double bond equivalents) and 14-38 carbon numbers were identified by APPI FT-ICR MS. The heteroatom PAHs had similar DBEs and carbon number distribution as regular PAHs.

  14. Occurrence, distribution and health risk from polycyclic aromatic compounds (PAHs, oxygenated-PAHs and azaarenes) in street dust from a major West African Metropolis.

    Science.gov (United States)

    Bandowe, Benjamin A Musa; Nkansah, Marian Asantewah

    2016-05-15

    Scientific evidence suggests that the burden of disease on urban residents of sub-Saharan African Countries is increasing, partly as a result of exposure to elevated concentrations of toxic environmental chemicals. However, characterization of the levels, composition pattern and sources of polycyclic aromatic compounds (PACs) in environmental samples from African cities is still lacking. This study measured the PAHs, oxygenated-PAHs (OPAHs) and azaarene (AZAs) content of street dusts collected from Kumasi, Ghana (a major metropolis located in the tropical forest zone of West Africa). The ∑Alkyl+parent-PAHs, ∑OPAHs and ∑AZAs concentration in street dust averaged 2570 ng g(-1) (range: 181-7600 ng g(-1)), 833 ng g(-1) (57-4200 ng g(-1)) and 73 ng g(-1) (3.3-240 ng g(-1)), respectively. The concentrations of ∑Alkyl+parent-PAHs were strongly correlated (n=25) with ∑OPAHs (r=0.96, p10(-6) indicating high risk of contracting cancer from exposure to street dust from Kumasi. The contribution of OPAHs, AZAs, and alkyl-PAHs in street dust to cancer risk could not be quantified because of lack of toxicity equivalency factors for these compounds; however this could be significant because of their high concentration and known higher toxicity of some polar PACs and alkyl-PAHs than their related parent-PAHs. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Historical Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Marine Sediment Cores from Northwest Spain.

    Science.gov (United States)

    Pérez-Fernández, Begoña; Viñas, Lucía; Bargiela, Jesica

    2016-11-01

    The northwest coast of Spain is characterized by an irregular coastline rich in marine life and with the highest mussel production in Europe. Taking this into account, the characterization of the pollution levels and the sources involved appear necessary. Not only were parent Polycyclic Aromatic Hydrocarbons (PAHs) analysed but also their alkylated homologues. In total, 35 compounds were analyzed in 5 sediment cores. Sediments were collected using a box core dredge and extracted by (Pressurized Liquid Extraction) whilst the quantification of PAHs was performed using gas chromatography coupled to mass spectrometry (GC-MS). The total concentration detected varied from 49.6 to 2489 ng g -1 dry weight (d.w.) of which parent PAHs ranged from 44.5 to 2254 ng g -1 d.w. and alkylated PAHs varied from 5.04 to 317 ng g -1 d.w. Temporal and spatial evolution were outlined and pollution sources were identified along with a possible correlation between this pollution and local history and industry. Most of the PAHs from the superficial samples have a biomass and coal combustion profile, and some specific, localized events are reflected in the total PAH concentration evolution. Moreover, the study of the deepest layers of the sampled cores provides a baseline to develop background concentration values that will help in future sediment quality assessment.

  16. Polycyclic aromatic hydrocarbons in Northwest Atlantic finfish : available and needed knowledge for monitoring

    International Nuclear Information System (INIS)

    Hellou, J.; Leonard, J.; Collier, T.K.; Ariese, F.

    2004-01-01

    This study addressed some of the human health risk factors associated with polycyclic aromatic hydrocarbons (PAHs). These toxic chemicals degrade with time, depending on their source and structure. However, they can also persist long enough and exist at elevated levels to have a possible toxic risk associated with exposure. Most studies on invertebrates have examined bioaccumulation rather than biotransformation. Biotransformation occurs more readily in vertebrates because they have active mixed function oxygenase enzymes. The fate of the oxidation products is of particular interest because they are associated with the formation of DNA-adducts that have carcinogenic effects. Exposed organisms can be monitored for chemical, biochemical or biological endpoints. This study examined PAH concentrations in small finfish such as capelin, sand lance, American plaice, yellowtail flounder and herring collected from the district of the Northwest Atlantic Fisheries Organization. Variables included pool size, size differences within species, lipid content and location. The exposure routes for bioaccumulation were respiration and feeding. The two sources were combustion and fossil fuels. All samples showed signs of alkylated naphthalene which would have been take up by respiration. They were likely derived from petroleum seeps in the water column. Smaller fish had higher concentrations of 3 alkylated naphthalenes. This paper described the relative concentrations in whole fish and internal organs. Measurements carried out prior to development of the Hibernia oil fields revealed baseline levels. Biotransformation products must yet be measured in order to assess future exposure and effects, particularly with long term exposure to waste water. 7 refs., 1 fig

  17. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 127; Issue 9. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids and their catalytic studies in multi-component Biginelli reaction. Sankaranarayanan Nagarajan Tanveer M Shaikh Elango Kandasamy. Volume 127 Issue 9 September 2015 pp 1539- ...

  18. Ionic liquid containing hydroxamate and N-alkyl sulfamate ions

    Science.gov (United States)

    Friesen, Cody A.; Wolfe, Derek; Johnson, Paul Bryan

    2016-03-15

    Embodiments of the invention are related to ionic liquids and more specifically to ionic liquids used in electrochemical metal-air cells in which the ionic liquid includes a cation and an anion selected from hydroxamate and/or N-alkyl sulfamate anions.

  19. Alkyl Radicals as Hydrogen Bond Acceptors: Computational Evidence

    DEFF Research Database (Denmark)

    Hammerum, Steen

    2009-01-01

    , and gives rise to pronounced shifts of IR stretching frequencies and to increased absorption intensities. The hydrogen bond acceptor properties of alkyl radicals equal those of many conventional acceptors, e.g., the bond length changes and IR red-shifts suggest that tert-butyl radicals are slightly better...

  20. A new route alpha-alkyl-alpha-fluoromethylenebisphosphonates

    Czech Academy of Sciences Publication Activity Database

    Beier, Petr; Opekar, Stanislav; Zibinsky, M.; Bychinskaya, I.; Prakash, G. K. S.

    2011-01-01

    Roč. 9, č. 11 (2011), s. 4035-4038 ISSN 1477-0520 R&D Projects: GA ČR GP203/08/P310 Institutional research plan: CEZ:AV0Z40550506 Keywords : fluorine * phosphonate * alkylation Subject RIV: CC - Organic Chemistry Impact factor: 3.696, year: 2011

  1. A Green Alternative to Aluminum Chloride Alkylation of Xylene

    Science.gov (United States)

    Sereda, Grigoriy A.; Rajpara, Vikul B.

    2007-01-01

    An acutely less toxic 2-bromobutane is used to develop a simple graphite-promoted procedure of alkylation of p-xylene. It is further demonstrated that aluminum chloride is not required, the need for aqueous workup is eliminated, waste solutions are not produced and the multiple use of the catalyst is allowed.

  2. An efficient, heterogeneous and reusable catalyst for -alkylation of ...

    Indian Academy of Sciences (India)

    Fe(HSO4)3(FHS) was used as an efficient catalyst for the heterogeneous addition of a series of benzylic and allylic alcohols to various -dicarbonyl compounds, which afforded moderate to excellent yields of -alkylated products in 1,2-dichloroethane. In comparison with the previous methods, the present research ...

  3. Ruthenium-Catalyzed Alkylation of Oxindole with Alcohols

    DEFF Research Database (Denmark)

    Jensen, Thomas; Madsen, Robert

    2009-01-01

    An atom-economical and solvent-free catalytic procedure for the mono-3-alkylation of oxindole with alcohols is described. The reaction is mediated by the in situ generated catalyst from RuCl3 center dot xH(2)O and PPh3 in the presence of sodium hydroxide, The reactions proceed in good to excellent...

  4. Synthesis of hydroxytyrosyl alkyl ethers from olive oil waste waters

    OpenAIRE

    Espartero Sánchez, José Luis; Madrona, Andrés; Pereira Cano, Gema; Mateos, Raquel; Rodríguez, Guillermo; Trujillo, Mariana; Fernández Bolaños, Juan

    2009-01-01

    The preparation of a new type of derivatives of the naturally occurring antioxidant hydroxytyrosol is reported. Hydroxytyrosyl alkyl ethers were obtained in high yield by a three-step procedure starting from hydroxytyrosol isolated from olive oil waste waters. Preliminary results obtained by the Rancimat method have shown that these derivatives retain the high protective capacity of free hydroxytyrosol.

  5. Synthesis of Hydroxytyrosyl Alkyl Ethers from Olive Oil Waste Waters

    Directory of Open Access Journals (Sweden)

    Juan Fernández-Bolaños

    2009-05-01

    Full Text Available The preparation of a new type of derivatives of the naturally occurring antioxidant hydroxytyrosol is reported. Hydroxytyrosyl alkyl ethers were obtained in high yield by a three-step procedure starting from hydroxytyrosol isolated from olive oil waste waters. Preliminary results obtained by the Rancimat method have shown that these derivatives retain the high protective capacity of free hydroxytyrosol.

  6. Students' Understanding of Alkyl Halide Reactions in Undergraduate Organic Chemistry

    Science.gov (United States)

    Cruz-Ramirez de Arellano, Daniel

    2013-01-01

    Organic chemistry is an essential subject for many undergraduate students completing degrees in science, engineering, and pre-professional programs. However, students often struggle with the concepts and skills required to successfully solve organic chemistry exercises. Since alkyl halides are traditionally the first functional group that is…

  7. Direct determination of adipic acid in urine by extractive alkylation.

    Science.gov (United States)

    Adinolfe, N A; Bicking, M K

    1985-09-01

    Extractive alkylation procedures are shown to be inhibited by low levels of Cl-. The chloride concentration may be reduced by mercury(II) complexation and dilution. The mercury(II) also enhances the reaction yield through some undetermined mechanism. Minor modifications of procedures for standards allow direct determination of adipic acid in urine.

  8. Microbial degradation of n-alkyl tetrahydrothiophenes found in petroleum

    Energy Technology Data Exchange (ETDEWEB)

    Fedorak, P.M.; Payzant, J.D.; Montgomery, D.S.; Westlake, D.W.S.

    1988-05-01

    Although n-alkyl-substituted tetrahydrothiophenes are found in nonbiodegraded petroleums, they are not found in petroleums which have undergone biodegradation in their reservoirs. These observations suggested that this group of compounds with alkyl chain lengths from approximately C/sub 10/ to at least C/sub 30/ is biodegradable. Two of these sulfides, 2-n-dodecyltetrahydrothiophene (DTHT) and 2-n-undecyltetrahydrothiophene, were synthesized, and their biodegradabilities were tested by using five gram-positive, n-alkane-degrading bacterial isolates. The alkyl side chains of these compounds were oxidized, and the major intermediates found in 2-n-undecyltetrahydrothiophene- and DTHT-metabolizing cultures were 2-tetrahydrothiophenecarboxylic acid (THTC) and 2-tetrahydrothiopheneacetic acid (THTA), respectively. Four n-alkane-degrading fungi were also shown to degrade DTHT, yielding both THTA and THTC. Quantitation of tetrahydrothiophene ring-containing products in 28-day-old bacterial and fungal cultures suggested that THTC and THTA were metabolized further to unidentified products. In addition, two of the bacterial isolates were shown to degrade a mixture of n-alkyl tetrahydrothiophenes isolated from Bellshill Lake crude oil.

  9. Role of clay as catalyst in Friedel–Craft alkylation

    Indian Academy of Sciences (India)

    Role of clay as catalyst in Friedel–Craft alkylation. TANUSHREE CHOUDHURY. ∗ and NIRENDRA M MISRA†. Department of Chemistry, School of Advanced Sciences, VIT University Chennai Campus,. Vandalur- Kelambakkam Road, Chennai- 600048, India. †Department of Applied Chemistry, Indian School of Mines ...

  10. Leukemia after therapy with alkylating agents for childhood cancer

    International Nuclear Information System (INIS)

    Tucker, M.A.; Meadows, A.T.; Boice, J.D. Jr.

    1987-01-01

    The risk of leukemia was evaluated in 9,170 2-or-more-year survivors of childhood cancer in the 13 institutions of the Late Effects Study Group. Secondary leukemia occurred in 22 nonreferred individuals compared to 1.52 expected, based on general population rates [relative risk (RR) = 14; 95% confidence interval (CI), 9-22]. The influence of therapy for the first cancer on subsequent leukemia risk was determined by a case-control study conducted on 25 cases and 90 matched controls. Treatment with alkylating agents was associated with a significantly elevated risk of leukemia (RR = 4.8; 95% CI, 1.2-18.9). A strong dose-response relationship was also observed between leukemia risk and total dose of alkylating agents, estimated by an alkylator score. The RR of leukemia reached 23 in the highest dose category. Radiation therapy, however, did not increase risk. Although doxorubicin was also identified as a possible risk factor, the excess risk of leukemia following treatment for childhood cancer appears almost entirely due to alkylating agents

  11. Alkylation of isobutane with light olefins catalyzed by zeolite beta

    NARCIS (Netherlands)

    Nivarthy, G.S.; Feller, A.P.; Seshan, Kulathuiyer; Lercher, J.A.

    2000-01-01

    Alkylation of isobutane with ethene and propene was studied over an H-BEA catalyst in a well-stirred reactor. Under similar conditions of space velocity and paraffin-to-olefin feed ratio, lower initial olefin conversions were observed with ethene or propene than those reported earlier for butene.

  12. Isobutane/olefin alkylation - present state and recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Feller, A.; Lercher, J.A. [Inst. fuer Technische Chemie, Technische Univ. Muenchen (Germany)

    2002-12-01

    Isobutane/alkene alkylation is reviewed with respect to recent process developments based on liquid and solid acid catalysts. The reaction mechanism and its consequences for both liquid and solid acid based processes is briefly discussed. Established liquid acid catalyzed processes are introduced followed by the description of new processes based on solid acids, which are currently under development. (orig.)

  13. Aromatic claw: A new fold with high aromatic content that evades structural prediction: Aromatic Claw

    Energy Technology Data Exchange (ETDEWEB)

    Sachleben, Joseph R. [Biomolecular NMR Core Facility, University of Chicago, Chicago Illinois; Adhikari, Aashish N. [Department of Chemistry, University of Chicago, Chicago Illinois; Gawlak, Grzegorz [Department of Biochemistry and Molecular Biology, University of Chicago, Chicago Illinois; Hoey, Robert J. [Department of Biochemistry and Molecular Biology, University of Chicago, Chicago Illinois; Liu, Gaohua [Northeast Structural Genomics Consortium (NESG), Department of Molecular Biology and Biochemistry, School of Arts and Sciences, and Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, and Center for Advanced Biotechnology and Medicine, Rutgers, The State University of New Jersey, Piscataway New Jersey; Joachimiak, Andrzej [Department of Biochemistry and Molecular Biology, University of Chicago, Chicago Illinois; Biological Sciences Division, Argonne National Laboratory, Argonne Illinois; Montelione, Gaetano T. [Northeast Structural Genomics Consortium (NESG), Department of Molecular Biology and Biochemistry, School of Arts and Sciences, and Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, and Center for Advanced Biotechnology and Medicine, Rutgers, The State University of New Jersey, Piscataway New Jersey; Sosnick, Tobin R. [Department of Biochemistry and Molecular Biology, University of Chicago, Chicago Illinois; Koide, Shohei [Department of Biochemistry and Molecular Biology, University of Chicago, Chicago Illinois; Department of Biochemistry and Molecular Pharmacology and the Perlmutter Cancer Center, New York University School of Medicine, New York New York

    2016-11-10

    We determined the NMR structure of a highly aromatic (13%) protein of unknown function, Aq1974 from Aquifex aeolicus (PDB ID: 5SYQ). The unusual sequence of this protein has a tryptophan content five times the normal (six tryptophan residues of 114 or 5.2% while the average tryptophan content is 1.0%) with the tryptophans occurring in a WXW motif. It has no detectable sequence homology with known protein structures. Although its NMR spectrum suggested that the protein was rich in β-sheet, upon resonance assignment and solution structure determination, the protein was found to be primarily α-helical with a small two-stranded β-sheet with a novel fold that we have termed an Aromatic Claw. As this fold was previously unknown and the sequence unique, we submitted the sequence to CASP10 as a target for blind structural prediction. At the end of the competition, the sequence was classified a hard template based model; the structural relationship between the template and the experimental structure was small and the predictions all failed to predict the structure. CSRosetta was found to predict the secondary structure and its packing; however, it was found that there was little correlation between CSRosetta score and the RMSD between the CSRosetta structure and the NMR determined one. This work demonstrates that even in relatively small proteins, we do not yet have the capacity to accurately predict the fold for all primary sequences. The experimental discovery of new folds helps guide the improvement of structural prediction methods.

  14. Hexacoordinate bonding and aromaticity in silicon phthalocyanine.

    Science.gov (United States)

    Yang, Yang

    2010-12-23

    Si-E bondings in hexacoordinate silicon phthalocyanine were analyzed using bond order (BO), energy partition, atoms in molecules (AIM), electron localization function (ELF), and localized orbital locator (LOL). Bond models were proposed to explain differences between hexacoordinate and tetracoordinate Si-E bondings. Aromaticity of silicon phthalocyanine was investigated using nucleus-independent chemical shift (NICS), harmonic oscillator model of aromaticity (HOMA), conceptual density functional theory (DFT), ring critical point (RCP) descriptors, and delocalization index (DI). Structure, energy, bonding, and aromaticity of tetracoordinate silicon phthalocyanine were studied and compared with hexacoordinate one.

  15. Conservation of medicinal and aromatic plants

    Directory of Open Access Journals (Sweden)

    Šveistytė, Laima

    2016-07-01

    Full Text Available The conservation of medicinal and aromatic plants includes ex situ and in situ methods. The genetic recourses of medicinal and aromatic plants are stored, studied and constantly maintained in the field collections of the Institute of Botany of Nature Research Centre, Kaunas Botanical Garden of Vytautas Magnus University and Aleksandras Stulginskis University of Agriculture. Presently seeds of 214 accessions representing 38 species of medicinal and aromatic plants are stored in a long-term storage in the Plant Gene Bank. The data about national genetic resources are collected and stored in the Central Database of the Plant Gene Bank.

  16. The carriers of the unidentified infrared emission features: Clues from polycyclic aromatic hydrocarbons with aliphatic sidegroups

    Science.gov (United States)

    Yang, X. J.; Glaser, R.; Li, Aigen; Zhong, J. X.

    2017-04-01

    The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, 11.3 and 12.7 μ m are ubiquitously seen in a wide variety of astrophysical regions in the Milky Way and nearby galaxies as well as distant galaxies at redshifts z ≳ 4. The UIE features are characteristic of the stretching and bending vibrations of aromatic hydrocarbon materials. The 3.3 μ m feature which results from the C-H stretching vibration in aromatic species is often accompanied by a weaker feature at 3.4 μ m. The 3.4 μ m feature is often thought to result from the C-H stretch of aliphatic groups attached to the aromatic systems. The ratio of the observed intensity of the 3.3 μ m aromatic C-H feature (I3.3) to that of the 3.4 μ m aliphatic C-H feature (I3.4) allows one to estimate the aliphatic fraction (e.g., NC, aliph/NC, arom, the number of C atoms in aliphatic units to that in aromatic rings) of the carriers of the UIE features, provided that the intrinsic oscillator strengths (per chemical bond) of the 3.3 μ m aromatic C-H stretch (A3.3) and the 3.4 μ m aliphatic C-H stretch (A3.4) are known. In this review we summarize the computational results on A3.3 and A3.4 and their implications for the aromaticity and aliphaticity of the UIE carriers. We use density functional theory and second-order perturbation theory to derive A3.3 and A3.4 from the infrared vibrational spectra of seven polycyclic aromatic hydrocarbon (PAH) molecules with various aliphatic substituents (e.g., methyl-, dimethyl-, ethyl-, propyl-, butyl-PAHs, and PAHs with unsaturated alkyl chains). The mean band strengths of the aromatic (A3.3) and aliphatic (A3.4) C-H stretches are derived and then employed to estimate the aliphatic fraction of the carriers of the UIE features by comparing the ratio of the intrinsic band strength of the two stretches (A3.4/A3.3) with the ratio of the observed intensities (I3.4/I3.3). We conclude that the UIE emitters are predominantly aromatic, as revealed by the observationally

  17. Predicting Alkylate Yield and its Hydrocarbon Composition for Sulfuric Acid Catalyzed Isobutane Alkylation with Olefins Using the Method of Mathematical Modeling

    OpenAIRE

    Nurmakanova, А. Е.; Ivashkina, Elena Nikolaevna; Ivanchina, Emilia Dmitrievna; Dolganov, I. A.; Boychenko, S. S.

    2015-01-01

    The article provides the results of applied mathematical model of isobutane alkylation with olefins catalyzed by sulfuric acid to predict yield and hydrocarbon composition of alkylate caused by the changes in the feedstock composition and process parameters. It is shown that the alkylate produced from feedstock with less mass fraction of isobutane has lower octane value. Wherein the difference in composition of the feedstock contributes to antiknock index by the amount of 1.0-2.0 points.

  18. Design of novel antitumor DNA alkylating agents: the benzacronycine series.

    Science.gov (United States)

    David-Cordonnier, Marie-Hélène; Laine, William; Gaslonde, Thomas; Michel, Sylvie; Tillequin, Francois; Koch, Michel; Léonce, Stéphane; Pierré, Alain; Bailly, Christian

    2004-03-01

    Acronycine, a natural alkaloid originally extracted from the bark of the Australian ash scrub Acronychia baueri, has shown a significant antitumor activity in animal models. Acronycine has been tested against human cancers in the early 1980s, but the clinical trials showed modest therapeutic effects and its development was rapidly discontinued. In order to optimize the antineoplastic effect, different benzoacronycine derivatives were synthesized. Among those, the di-acetate compound S23906-1 was recently identified as a promising anticancer drug candidate and a novel alkylating agent specifically reacting with the exocylic 2-NH2 group of guanines in DNA. The study of DNA bonding capacity of acronycine derivatives leads to the identification of the structural requirements for DNA alkylation. In nearly all cases, the potent alkylating agents, such as S23906-1, were found to be much more cytotoxic than the unreactive analogs such as acronycine itself or diol derivatives. Alkylation of DNA by the monoacetate derivative S28687-1, which is a highly reactive hydrolysis metabolite of S23906-1, occurs with a marked preference for the N2 position of guanine. Other bionucleophiles can react with S23906-1. The benzacronycine derivatives, which efficiently alkylate DNA, also covalently bind to the tripeptide glutathione (GSH) but not to the oxidized product glutathione disulfide. Here we review the reactivity of S23906-1 and some derivatives toward DNA and GSH. The structure-activity relationships in the benzacronycine series validate the reaction mechanism implicating DNA as the main molecular target. S23906-1 stands as the most promising lead of a medicinal chemistry program aimed at discovering novel antitumor drugs based on the acronycine skeleton.

  19. Synthesis of a Fluorine-Containing Cis-Cisoidal One-Handed Helical Polyphenylacetylene and Application of Highly Selective Photocyclic Aromatization Product on Oxygen Permselective Membrane.

    Science.gov (United States)

    Zang, Yu; Yin, Guanwu; Aoki, Toshiki; Teraguchi, Masahiro; Kaneko, Takashi; Ma, Liqun; Jia, Hongge

    2015-08-01

    A novel phenylacetylene monomer having a perfluorinated alkyl group (M-F) was synthesized and polymerized in a chiral catalytic system to yield a one-handed helical polymer. The ability and efficiency of the chiral induction of the fluorine-containing monomer in the helix-sense-selective polymerization (HSSP) was much higher than those of a monomer having the corresponding alkyl group (M-H) we reported before. The resulting polymer showed cis-cisoidal one-handed helical conformation, and was suitable for highly selective photocyclic aromatization (SCAT) to give a 2D surface modifier (). Oxygen permselectivity through a base polymer membrane was highly enhanced from 1.83 to 2.36 by adding a small amount (1-5 wt%) of the 2D surface modifier . The improvement was thought to be caused by improvement of solution selectivity on the membrane surface which the 2D surface modifier effectively covered. © 2015 Wiley Periodicals, Inc.

  20. Co-catalyzed cross-coupling of alkyl halides with tertiary alkyl Grignard reagents using a 1,3-butadiene additive.

    Science.gov (United States)

    Iwasaki, Takanori; Takagawa, Hiroaki; Singh, Surya P; Kuniyasu, Hitoshi; Kambe, Nobuaki

    2013-07-03

    The cobalt-catalyzed cross-coupling of alkyl (pseudo)halides with alkyl Grignard reagents in the presence of 1,3-butadiene as a ligand precursor and LiI is described. Sterically congested quaternary carbon centers could be constructed by using tertiary alkyl Grignard reagents. This reaction proceeds via an ionic mechanism with inversion of stereochemistry at the reacting site of the alkyl halide and is compatible with various functional groups. The use of both 1,3-butadiene and LiI was essential for achieving high yields and high selectivities.

  1. Study of hydrogen mobility by hydrogen-deuterium exchange. II. Theoretical kinetic study in alkyl and amino-alkyl pyrimidines

    International Nuclear Information System (INIS)

    Pompon, Alain

    1975-01-01

    Alkyl groups bound to the pyrimidine ring can be deuterium substituted on the carbon adjacent to the ring, in acidic D 2 O; kinetic equations corresponding to various exchange mechanism hypothesis are established. It is shown that theoretical and experimental results can be compared in order to precise the mechanism and to measure the characteristic parameters of the exchange reaction [fr

  2. Determination of alkylation of bacterial DNA as a rapid test for toxicological evaluation of alkylating xenobiotic agents

    Energy Technology Data Exchange (ETDEWEB)

    Botzenhart, K.; Waldner-Sander, S.; Schweinsberg, F.

    1986-05-01

    Alkylated purine bases from hydrolized DNA can be separated by HPLC and quantified with a fluorescence detector. We applied this method to bacterial DNA. 7-methylguanine was detected after treatment of Serratia marcescens with iodoacetamide, dimethyl sulfate and with polluted air.

  3. Isomeric Detergent Comparison for Membrane Protein Stability: Importance of Inter-Alkyl-Chain Distance and Alkyl Chain Length.

    Science.gov (United States)

    Cho, Kyung Ho; Hariharan, Parameswaran; Mortensen, Jonas S; Du, Yang; Nielsen, Anne K; Byrne, Bernadette; Kobilka, Brian K; Loland, Claus J; Guan, Lan; Chae, Pil Seok

    2016-12-14

    Membrane proteins encapsulated by detergent micelles are widely used for structural study. Because of their amphipathic property, detergents have the ability to maintain protein solubility and stability in an aqueous medium. However, conventional detergents have serious limitations in their scope and utility, particularly for eukaryotic membrane proteins and membrane protein complexes. Thus, a number of new agents have been devised; some have made significant contributions to membrane protein structural studies. However, few detergent design principles are available. In this study, we prepared meta and ortho isomers of the previously reported para-substituted xylene-linked maltoside amphiphiles (XMAs), along with alkyl chain-length variation. The isomeric XMAs were assessed with three membrane proteins, and the meta isomer with a C 12 alkyl chain was most effective at maintaining solubility/stability of the membrane proteins. We propose that interplay between the hydrophile-lipophile balance (HLB) and alkyl chain length is of central importance for high detergent efficacy. In addition, differences in inter-alkyl-chain distance between the isomers influence the ability of the detergents to stabilise membrane proteins. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Synthesis and evaluation of aromaticity and tautomerization of ...

    Indian Academy of Sciences (India)

    Aromaticity of pyrazolopyridazin(on)es was investigated using NICS(0), NICS(1), NICSzz(1), FIPC-NICS and HOMA aromaticity indexes and it was observed that aromaticity of pyridazin(on)es was amenable to aromaticity of pyrazole and vice versa. Some tautomeric forms of pyridazinone were analyzedand the localized ...

  5. Oil droplet fouling and differential toxicokinetics of polycyclic aromatic hydrocarbons in embryos of Atlantic haddock and cod.

    Directory of Open Access Journals (Sweden)

    Lisbet Sørensen

    Full Text Available The impact of crude oil pollution on early life stages (ELS of fish, including larvae and embryos, has received considerable attention in recent years. Of the organic components present in crude oil, polycyclic aromatic hydrocarbons (PAHs are considered the main class of compounds responsible for toxic effects in marine organisms. Although evidence suggests that they are more toxic, alkylated PAHs remain much less studied than their unsubstituted congeners. Recently, it was established that embryos of Atlantic haddock (Melanogrammus aeglefinus are particularly sensitive to dispersed crude oil, and it was hypothesized that this was caused by direct interaction with crude oil droplets, which adhered to the chorion of exposed embryos. Such a phenomenon would increase the potential for uptake of less water-soluble compounds, including alkylated PAHs. In the current study, we compared the uptake of parent and alkylated PAHs in Atlantic cod (Gadus morhua and haddock embryos exposed to dispersed crude oil at a range of environmentally relevant concentrations (10-600 μg oil/liter seawater. Although the species are biologically very similar, the cod chorion does not become fouled with oil droplets, even when the two species are exposed to dispersions of crude oil droplets under similar conditions. A close correlation between the degree of fouling and toxicological response (heart defects, craniofacial malformation was observed. Oil droplet fouling in haddock led to both quantitative and qualitative differences in PAH uptake. Finally, kinetic data on a large suite of PAHs showed differential elimination, suggesting differential metabolism of unsubstituted versus alkylated compounds.

  6. Inhibitory Activities of Alkyl Syringates and Related Compounds on Aflatoxin Production.

    Science.gov (United States)

    Furukawa, Tomohiro; Iimura, Kurin; Kimura, Taichi; Yamamoto, Toshiyoshi; Sakuda, Shohei

    2016-06-07

    Inhibitors of aflatoxin production of aflatoxigenic fungi are useful for preventing aflatoxin contamination in crops. As methyl syringate weakly inhibits aflatoxin production, aflatoxin production inhibitory activities of additional alkyl syringates with alkyl chains from ethyl to octyl were examined. Inhibitory activity toward aflatoxin production of Aspergillus flavus became stronger as the length of the alkyl chains on the esters became longer. Pentyl, hexyl, heptyl, and octyl syringates showed strong activity at 0.05 mM. Heptyl and octyl parabens, and octyl gallate also inhibited aflatoxin production as strongly as octyl syringate. Alkyl parabens and alkyl gallates inhibit the complex II activity of the mitochondrial respiration chain; thus, whether alkyl syringates inhibit complex II activity was examined. Inhibitory activities of alkyl syringates toward complex II also became stronger as the length of the alkyl chains increased. The complex II inhibitory activity of octyl syringate was comparable to that of octyl paraben and octyl gallate. These results suggest that alkyl syringates, alkyl parabens, and alkyl gallates, including commonly used food additives, are useful for aflatoxin control.

  7. Inhibitory Activities of Alkyl Syringates and Related Compounds on Aflatoxin Production

    Directory of Open Access Journals (Sweden)

    Tomohiro Furukawa

    2016-06-01

    Full Text Available Inhibitors of aflatoxin production of aflatoxigenic fungi are useful for preventing aflatoxin contamination in crops. As methyl syringate weakly inhibits aflatoxin production, aflatoxin production inhibitory activities of additional alkyl syringates with alkyl chains from ethyl to octyl were examined. Inhibitory activity toward aflatoxin production of Aspergillus flavus became stronger as the length of the alkyl chains on the esters became longer. Pentyl, hexyl, heptyl, and octyl syringates showed strong activity at 0.05 mM. Heptyl and octyl parabens, and octyl gallate also inhibited aflatoxin production as strongly as octyl syringate. Alkyl parabens and alkyl gallates inhibit the complex II activity of the mitochondrial respiration chain; thus, whether alkyl syringates inhibit complex II activity was examined. Inhibitory activities of alkyl syringates toward complex II also became stronger as the length of the alkyl chains increased. The complex II inhibitory activity of octyl syringate was comparable to that of octyl paraben and octyl gallate. These results suggest that alkyl syringates, alkyl parabens, and alkyl gallates, including commonly used food additives, are useful for aflatoxin control.

  8. Activity relationships for aromatic crown ethers

    CERN Document Server

    Wilson, M J

    1998-01-01

    This thesis involves an investigation of aromatic crown ethers and a study of their binding constants for alkali metals. The study was motivated by the current needs of the semiconductor industry to improve the scavenging of mobile ions from fabricated circuits. A number of aromatic crown ethers have been sulphonated in an attempt to improve their water solubility and cation binding activity. These materials have been extensively studied and their binding activity determined. In collaboration with a molecular modelling study, the effect of ionisable sulphonate groups on the macrocycles' behaviour has been investigated. The broader issue of the effect of substituents in aromatic crown ethers has also been studied with the preparation of a wide range of substituted crown ethers. The cation binding activity of these materials has been found to bear a simple relationship to the electron withdrawing nature of the aromatic substituents. This relationship can be accurately monitored using electronic charge densities...

  9. Graphite Oxide and Aromatic Amines : Size Matters

    NARCIS (Netherlands)

    Spyrou, Konstantinos; Calvaresi, Matteo; Diamanti, Evmorfi A. K.; Tsoufis, Theodoros; Gournis, Dimitrios; Rudolf, Petra; Zerbetto, Francesco

    2015-01-01

    Experimental and theoretical studies are performed in order to illuminate, for first time, the intercalation mechanism of polycyclic aromatic molecules into graphite oxide. Two representative molecules of this family, aniline and naphthalene amine are investigated. After intercalation, aniline

  10. International congress on aromatic and medicinal plants

    International Nuclear Information System (INIS)

    2009-01-01

    Full Text : In Morocco, medicinal and aromatic plants occupy an important place in the traditional care system of a large number of local people. They are also economically strong potential, but unfortunately they are not valued enough. Indeed, Morocco by its privileged geographical position in the Mediterranean basin and its floristic diversity (with a total of over 4,200 species and subspecies of which over 500 are recognized as medicinal and aromatic plants), is a leading provider of traditional global market. In this context and given the back label of the natural global, group research and studies on Aromatic and Medicinal Plants (GREPAM), the Faculty of Semlalia and University Cadi Ayyad, organize: the International Congress on Medicinal and Aromatic Plants CIPAM 2009. The organization of this conference is part of scientific research developed by the GREPAM. [fr

  11. Microbial transformation of chlorinated aromatics in sediments

    NARCIS (Netherlands)

    Beurskens, J.E.M.

    1995-01-01

    Numerous contaminants like heavy metals, polycyclic aromatic hydrocarbons (PAHs), chlorinated benzenes (CBs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo- p -dioxins (PCDDs) and polychlorinated furans (PCDFs) are detected in the major rivers in the

  12. Medicinally important aromatic plants with radioprotective activity.

    Science.gov (United States)

    Samarth, Ravindra M; Samarth, Meenakshi; Matsumoto, Yoshihisa

    2017-11-01

    Aromatic plants are often used as natural medicines because of their remedial and inherent pharmacological properties. Looking into natural resources, particularly products of plant origin, has become an exciting area of research in drug discovery and development. Aromatic plants are mainly exploited for essential oil extraction for applications in industries, for example, in cosmetics, flavoring and fragrance, spices, pesticides, repellents and herbal beverages. Although several medicinal plants have been studied to treat various conventional ailments only a handful studies are available on aromatic plants, especially for radioprotection. Many plant extracts have been reported to contain antioxidants that scavenge free radicals produced due to radiation exposure, thus imparting radioprotective efficacy. The present review focuses on a subset of medicinally important aromatic plants with radioprotective activity.

  13. Determination of carcinogenic polycyclic aromatic hydrocarbons ...

    African Journals Online (AJOL)

    Determination of carcinogenic polycyclic aromatic hydrocarbons (pahs), anthracene in different variety of fish samples in the Bangsai river of Bangladesh. F Yeasmin, SMM Rahman, S Rana, KJ Fatema, MA Hossain ...

  14. Aromaticity and relative stabilities of azines.

    Science.gov (United States)

    Wang, Yan; Wu, Judy I-Chia; Li, Qianshu; Schleyer, Paul von Ragué

    2010-11-05

    The most refined nucleus-independent chemical shift index (NICS(0)(πzz)) and the extra cyclic resonance energies (ECREs), based on the block localized wave function (BLW) method, show that the aromaticity of all azines is like that of benzene. The same is true for aza-naphthalenes relative to naphthalene. The lower relative energies of isomers with vicinal N's are due to the weakness of NN bonds rather than to reduced aromaticity.

  15. Aromatic Medicinal Plants from Tajikistan (Central Asia).

    Science.gov (United States)

    Sharopov, Farukh S; Zhang, Hanjing; Wink, Michael; Setzer, William N

    2015-02-17

    Tajikistan is a small country located in Central Asia. The mostly mountainous terrain with a continental, subtropical, and semiarid climate, is characterized by diverse flora. Many people in Tajikistan rely on medicinal plants as their traditional form of medicine to prevent and cure health disorders. Aromatic medicinal plants, in particular, have played an important role for the local people. In this review, we present a summary of the uses of 18 aromatic medicinal plants from Tajikistan and their compositions of secondary metabolites.

  16. Carbohydrate-Aromatic Interactions in Proteins.

    Science.gov (United States)

    Hudson, Kieran L; Bartlett, Gail J; Diehl, Roger C; Agirre, Jon; Gallagher, Timothy; Kiessling, Laura L; Woolfson, Derek N

    2015-12-09

    Protein-carbohydrate interactions play pivotal roles in health and disease. However, defining and manipulating these interactions has been hindered by an incomplete understanding of the underlying fundamental forces. To elucidate common and discriminating features in carbohydrate recognition, we have analyzed quantitatively X-ray crystal structures of proteins with noncovalently bound carbohydrates. Within the carbohydrate-binding pockets, aliphatic hydrophobic residues are disfavored, whereas aromatic side chains are enriched. The greatest preference is for tryptophan with an increased prevalence of 9-fold. Variations in the spatial orientation of amino acids around different monosaccharides indicate specific carbohydrate C-H bonds interact preferentially with aromatic residues. These preferences are consistent with the electronic properties of both the carbohydrate C-H bonds and the aromatic residues. Those carbohydrates that present patches of electropositive saccharide C-H bonds engage more often in CH-π interactions involving electron-rich aromatic partners. These electronic effects are also manifested when carbohydrate-aromatic interactions are monitored in solution: NMR analysis indicates that indole favorably binds to electron-poor C-H bonds of model carbohydrates, and a clear linear free energy relationships with substituted indoles supports the importance of complementary electronic effects in driving protein-carbohydrate interactions. Together, our data indicate that electrostatic and electronic complementarity between carbohydrates and aromatic residues play key roles in driving protein-carbohydrate complexation. Moreover, these weak noncovalent interactions influence which saccharide residues bind to proteins, and how they are positioned within carbohydrate-binding sites.

  17. Carbohydrate–Aromatic Interactions in Proteins

    Science.gov (United States)

    2015-01-01

    Protein–carbohydrate interactions play pivotal roles in health and disease. However, defining and manipulating these interactions has been hindered by an incomplete understanding of the underlying fundamental forces. To elucidate common and discriminating features in carbohydrate recognition, we have analyzed quantitatively X-ray crystal structures of proteins with noncovalently bound carbohydrates. Within the carbohydrate-binding pockets, aliphatic hydrophobic residues are disfavored, whereas aromatic side chains are enriched. The greatest preference is for tryptophan with an increased prevalence of 9-fold. Variations in the spatial orientation of amino acids around different monosaccharides indicate specific carbohydrate C–H bonds interact preferentially with aromatic residues. These preferences are consistent with the electronic properties of both the carbohydrate C–H bonds and the aromatic residues. Those carbohydrates that present patches of electropositive saccharide C–H bonds engage more often in CH−π interactions involving electron-rich aromatic partners. These electronic effects are also manifested when carbohydrate–aromatic interactions are monitored in solution: NMR analysis indicates that indole favorably binds to electron-poor C–H bonds of model carbohydrates, and a clear linear free energy relationships with substituted indoles supports the importance of complementary electronic effects in driving protein–carbohydrate interactions. Together, our data indicate that electrostatic and electronic complementarity between carbohydrates and aromatic residues play key roles in driving protein–carbohydrate complexation. Moreover, these weak noncovalent interactions influence which saccharide residues bind to proteins, and how they are positioned within carbohydrate-binding sites. PMID:26561965

  18. Contribution of aldehyde oxidase, xanthine oxidase, and aldehyde dehydrogenase on the oxidation of aromatic aldehydes.

    Science.gov (United States)

    Panoutsopoulos, Georgios I; Kouretas, Demetrios; Beedham, Christine

    2004-10-01

    Aliphatic aldehydes have a high affinity toward aldehyde dehydrogenase activity but are relatively poor substrates of aldehyde oxidase and xanthine oxidase. In addition, the oxidation of xenobiotic-derived aromatic aldehydes by the latter enzymes has not been studied to any great extent. The present investigation compares the relative contribution of aldehyde dehydrogenase, aldehyde oxidase, and xanthine oxidase activities in the oxidation of substituted benzaldehydes in separate preparations. The incubation of vanillin, isovanillin, and protocatechuic aldehyde with either guinea pig liver aldehyde oxidase, bovine milk xanthine oxidase, or guinea pig liver aldehyde dehydrogenase demonstrated that the three aldehyde oxidizing enzymes had a complementary substrate specificity. Incubations were also performed with specific inhibitors of each enzyme (isovanillin for aldehyde oxidase, allopurinol for xanthine oxidase, and disulfiram for aldehyde dehydrogenase) to determine the relative contribution of each enzyme in the oxidation of these aldehydes. Under these conditions, vanillin was rapidly oxidized by aldehyde oxidase, isovanillin was predominantly metabolized by aldehyde dehydrogenase activity, and protocatechuic aldehyde was slowly oxidized, possibly by all three enzymes. Thus, aldehyde oxidase activity may be a significant factor in the oxidation of aromatic aldehydes generated from amines and alkyl benzenes during drug metabolism. In addition, this enzyme may also have a role in the catabolism of biogenic amines such as dopamine and noradrenaline where 3-methoxyphenylacetic acids are major metabolites.

  19. Biochemical and chemical characterization of phenylglyoxal bis(guanylhydrazone), an aromatic analogue of mitoguazone.

    Science.gov (United States)

    Elo, H; Koskinen, M; Mutikainen, I; Tilus, P; Lampio, A; Keso, L; Vainio, A; Joutsjoki, V; Alli, K; Yliniva, A

    1996-10-01

    Since little has been known about the properties of aromatic analogues of the antineoplastic agent methylglyoxal bis(guanylhydrazone) (MGBG), an investigation was performed on phenylglyoxal bis(guanylhydrazone) (PhGBG). PhGBG competitively inhibited yeast adenosylmethionine decarboxylase (AdoMetDC) with a Ki of 65 microM. As compared to MGBG (Ki 0.23 microM), PhGBG is a much weaker inhibitor, being even weaker than the unsubstituted congener glyoxal bis(guanylhydrazone) (GBG, Ki 18 microM). PhGBG inhibited porcine kidney diamine oxidase (DAO) non-competitively, being a more potent inhibitor (Ki 0.12 microM) than GBG (Ki 0.17 microM) or MGBG (Ki 0.33 microM). Thus, PhGBG has an unfavourably high ratio of Ki(AdoMetDC)/Ki(DAO) for potential use for selectively inhibiting polyamine biosynthesis. This does not exclude the possibility that PhGBG or other aromatic congeners might have therapeutic value since the corresponding ratio of the antileukaemic congeners GBG and MGBG is also high as compared to many aliphatic non-antileukaemic analogues. The pKa1 and pKa2 values of PhGBG dication were found to be 6.39 +/- 0.02 and 8.64 +/- 0.02 respectively, their difference being distinctly larger than in the case of GBG or its C-alkylated analogues. This may result from decreased stability of the dication form, caused by the resonance effect or possibly by the inductive effect of the phenyl group. The species distribution of PhGBG (proportion of free base 5.5%, predominant species the monocation) at 37 degrees C resembles that of GBG and MGBG but is clearly different from that of non-antileukaemic C-alkylated analogues. These similarities suggest that PhGBG and its derivatives may be worth antitumour screening. Depending on the conditions used in the crystallization, three different types of crystals of PhGBG sulphate were obtained. Crystallography indicated that, in two of the types, the crystal consisted exclusively of the anti-anti isomer, i.e. the same isomer as has been

  20. Production of high-octane, unleaded motor fuel by alkylation of isobutane with isoamylenes obtained by dehydrogenation of isopentane

    Energy Technology Data Exchange (ETDEWEB)

    Hutson, T. Jr.; Hann, P.D.

    1981-01-31

    A process combination, with inter-cooperation, for producing high-octane alkylates comprising (a) dehydrogenating isopentane to isopentenes (amylenes), (b) introducing the mixture of said amylenes and unconverted isopentane into an HF alkylation unit for reaction with fresh or recycled isobutane, (c) separating the alkylation products into high octane alkylates, isopentane (for recycling to the dehydrogenation reactor) and isobutane (for recycling to the alkylation reactor).

  1. Alkylating agent (MNU)-induced mutation in space environment.

    Science.gov (United States)

    Ohnishi, T; Takahashi, A; Ohnishi, K; Takahashi, S; Masukawa, M; Sekikawa, K; Amano, T; Nakano, T; Nagaoka, S

    2001-01-01

    In recent years, some contradictory data about the effects of microgravity on radiation-induced biological responses in space experiments have been reported. We prepared a damaged template DNA produced with an alkylating agent (N-methyl-N-nitroso urea; MNU) to measure incorrect base-incorporation during DNA replication in microgravity. We examined whether mutation frequency is affected by microgravity during DNA replication for a DNA template damaged by an alkylating agent. Using an in vitro enzymatic reaction system, DNA synthesis by Taq polymerase or polymerase III was done during a US space shuttle mission (Discovery, STS-91). After the flight, DNA replication and mutation frequencies were measured. We found that there was almost no effect of microgravity on DNA replication and mutation frequency. It is suggested that microgravity might not affect at the stage of substrate incorporation in induced-mutation frequency. c2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

  2. Safety Assessment of Alkyl Esters as Used in Cosmetics.

    Science.gov (United States)

    Fiume, Monice M; Heldreth, Bart A; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2015-09-01

    The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of 237 alkyl esters for use in cosmetics. The alkyl esters included in this assessment have a variety of reported functions in cosmetics, with skin-conditioning agent being the most common function. The Panel reviewed available animal and clinical data in making its determination of safety on these ingredients, and where there were data gaps, similarity in structure, properties, functions, and uses of these ingredients allowed for extrapolation of the available toxicological data to assess the safety of the entire group. The Panel concluded that these ingredients are safe in cosmetic formulations in the present practices of use and concentration when formulated to be nonirritating. © The Author(s) 2015.

  3. Conformational Restriction of Peptides Using Dithiol Bis-Alkylation.

    Science.gov (United States)

    Peraro, L; Siegert, T R; Kritzer, J A

    2016-01-01

    Macrocyclic peptides are highly promising as inhibitors of protein-protein interactions. While many bond-forming reactions can be used to make cyclic peptides, most have limitations that make this chemical space challenging to access. Recently, a variety of cysteine alkylation reactions have been used in rational design and library approaches for cyclic peptide discovery and development. We and others have found that this chemistry is versatile and robust enough to produce a large variety of conformationally constrained cyclic peptides. In this chapter, we describe applications, methods, mechanistic insights, and troubleshooting for dithiol bis-alkylation reactions for the production of cyclic peptides. This method for efficient solution-phase macrocyclization is highly useful for the rapid production and screening of loop-based inhibitors of protein-protein interactions. © 2016 Elsevier Inc. All rights reserved.

  4. Method for reactivating solid catalysts used in alkylation reactions

    Science.gov (United States)

    Ginosar, Daniel M.; Thompson, David N.; Coates, Kyle; Zalewski, David J.; Fox, Robert V.

    2003-06-17

    A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

  5. Synthesis and Antioxidant Activity of Alkyl Nitroderivatives of Hydroxytyrosol

    Directory of Open Access Journals (Sweden)

    Elena Gallardo

    2016-05-01

    Full Text Available A series of alkyl nitrohydroxytyrosyl ether derivatives has been synthesized from free hydroxytyrosol (HT, the natural olive oil phenol, in order to increase the assortment of compounds with potential neuroprotective activity in Parkinson’s disease. In this work, the antioxidant activity of these novel compounds has been evaluated using Ferric Reducing Antioxidant Power (FRAP, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS, and Oxygen Radical Scavenging Capacity (ORAC assays compared to that of nitrohydroxytyrosol (NO2HT and free HT. New compounds showed variable antioxidant activity depending on the alkyl side chain length; compounds with short chains (2–4 carbon atoms maintained or even improved the antioxidant activity compared to NO2HT and/or HT, whereas those with longer side chains (6–8 carbon atoms showed lower activity than NO2HT but higher than HT.

  6. Rapid NIR determination of alkyl esters in virgin olive oil

    International Nuclear Information System (INIS)

    Cayuela, J.A.

    2017-01-01

    The regulation of The European Union for olive oil and olive pomace established the limit of 35 mg·kg-1 for fatty acids ethyl ester contents in extra virgin olive oils, from grinding seasons after 2016. In this work, predictive models have been established for measuring fatty acid ethyl and methyl esters and to measure the total fatty acid alkyl esters based on near infrared spectroscopy (NIRS), and used successfully for this purpose. The correlation coefficients from the external validation exercises carried out with these predictive models ranged from 0.84 to 0.91. Different classification tests using the same models for the thresholds 35 mg·kg-1 for fatty acid ethyl esters and 75 mg·kg-1 for fatty acid alkyl esters provided success percentages from 75.0% to 95.2%. [es

  7. New unit for sulfuric acid alkylation of isobutane by olefins

    Energy Technology Data Exchange (ETDEWEB)

    Khadzhiev, S.N.; Baiburskii, V.L.; Deineko, P.S.; Gruzdev, A.S.; Tagavov, I.T.

    1987-01-01

    The authors describe and illustrate a sulfuric acid alkylation unit with a horizontal contact. As a result of the use of this design solution, the isobutane/olefin ratio is 10/1 in comparison with 4/1 to 5/1 in the other types of units, namely vertical reactors and cascade tank reactors. The unit was designed to process the butane-butylene cut (BBC) and part of the propane-propylene cut (PPC) from the G-43-107 cat cracker. The unit design includes provisions for controlled caustic washing of the feed and dehydration in an electric field. The authors present the basic data obtained in the three months of unit operation after startup, in comparison with the operating indexes of a sulfuric acid alkylation unit.

  8. Alkylation of isobutane by ethylene: A thermodynamic study

    Energy Technology Data Exchange (ETDEWEB)

    Goupil, J.M.; Poirier, J.L.; Cornet, D. (Univ. of Caen (France). Lab. Catalyse et Spectrochimie)

    1994-03-01

    Alkylation of isobutane by ethylene produces mainly hexanes, but a variety of other compounds, alkanes or alkenes, may be formed by secondary reactions such as successive alkylations, isomerization, and ethylene polymerization. The equilibrium distribution of products is evaluated in the temperature range 280--680 K and at various initial compositions and pressures. Isomer groups are treated using Alberty's formulation. Calculations show that alkenes are thermodynamically unstable under usual reaction conditions. The equilibrium amounts of alkanes are such that C[sub 6] [much gt] C[sub 8] [much gt] C[sub 10] and heavy alkanes also appear unstable. The selective formation of particular isomers (dimethylbutanes, trimethylpentanes) is also integrated in the equilibrium equations. The calculated compositions (C[sub 6]:C[sub 8]:C[sub 10]) are compared with experimental data.

  9. Benign and efficient preparation of thioethers by solvent-free S-alkylation of thiols with alkyl halides catalyzed by potassium fluoride on alumina

    DEFF Research Database (Denmark)

    Nguyen, Kha Ngoc; Duus, Fritz; Luu, Thi Xuan Thi

    2016-01-01

    The preparation of thioethers by S-alkylation of various thiols with alkyl halides under solvent-free reaction conditions using potassium fluoride on alumina (KF/Al2O3) as a solid catalyst has been investigated in detail with respect to three different modes of reaction activation (ultrasound...

  10. Determination of heavy polycyclic aromatic hydrocarbons by non-aqueous reversed phase liquid chromatography: Application and limitation in refining streams.

    Science.gov (United States)

    Panda, Saroj K; Muller, Hendrik; Al-Qunaysi, Thunayyan A; Koseoglu, Omer R

    2018-01-19

    The heavy polycyclic aromatic hydrocarbons (HPAHs) cause detrimental effects to hydrocracker operations by deactivating the catalysts and depositing in the downstream of the reactor/ exchangers. Therefore, it is essential to continuously monitor the accumulation of HPAHs in a hydrocracker unit. To accurately measure the concentration of HPAHs, the development of a fast and reliable analytical method is inevitable. In this work, an analytical method based on non-aqueous reversed phase chromatography in combination with high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was developed. As a first step, five different types of stationary phases were evaluated for the separation of HPAHs in non-aqueous mode and the best suited phase was further used for the fractionation of HPAHs in a fractionator bottom sample obtained from a refinery hydrocracker unit. The eight major fractions or peaks obtained from the separation were further characterized by UV spectroscopy and FT-ICR MS and the compounds in the fractions were tentatively confirmed as benzoperylene, coronene, methylcoronene, naphthenocoronene, benzocoronene, dibenzoperylene, naphthocoronene and ovalene. The developed liquid chromatography method can be easily adapted in a refinery laboratory for the quantitation of HPAHs in hydrocracking products. The method was further tested to check the interference of sulfur aromatics and/or large alkylated aromatic hydrocarbons on the determination of HPAHs in hydrocracking products. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. 3-alkyl fentanyl analogues: Structure-activity-relationship study

    OpenAIRE

    Vučković, Sonja; Savić-Vujović, Katarina; Srebro, Dragana; Ivanović, Milovan; Došen-Mićović, Ljiljana; Stojanović, Radan; Prostran, Milica

    2012-01-01

    Introduction. Fentanyl belongs to 4-anilidopiperidine class of synthetic opioid analgesics. It is characterized by high potency, rapid onset and short duration of action. A large number of fentanyl analogues have been synthesized so far, both to establish the structure-activity-relationship (SAR) and to find novel, clinically useful analgesic drugs. Objective. In this study, newly synthesized 3-alkyl fentanyl analogues were examined for analgesic activity and compared with fentanyl. Methods. ...

  12. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids ...

    Indian Academy of Sciences (India)

    Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids and their catalytic studies in multi-component Biginelli ... ods involved use of a number of metal salts, such as Li,6 Fe,7–10 Cu,11,12 Ce,13 Zr,14 In,16 Bi,17 Yb, ..... in moderate yield, which might be due to poor solubility of starting materials. After extensive ...

  13. Iron-Catalyzed Alkylations of Aryl Sulfamates and Carbamates

    Science.gov (United States)

    Silberstein, Amanda L.; Ramgren, Stephen D.; Garg, Neil K.

    2012-01-01

    The alkylation of aryl sulfamates and carbamates using iron catalysis is reported. The method constructs sp2–sp3 carbon–carbon bonds and provides synthetically useful yields across a range of substrates (>35 examples). The directing group ability of sulfamates and carbamates, accompanied by their low reactivity toward conventional cross-couplings, render these substrates useful for the synthesis of polyfunctionalized arenes. PMID:22758657

  14. New potential of the reductive alkylation of amines

    International Nuclear Information System (INIS)

    Gusak, K N; Ignatovich, Zh V; Koroleva, E V

    2015-01-01

    Available data on the reductive alkylation of amines with carbonyl compounds — a key method for the preparation of secondary and tertiary amines — are described systematically. The review provides information on the relevant reducing agents and catalysts and on the use of chiral catalysts in stereo- and enantiocontrolled reactions of amine synthesis. The effect of the reactant and catalyst structures on the reaction rates and chemo- and stereo(enantio)selectivity is considered. The bibliography includes 156 references

  15. A new phenylethyl alkyl amide from the Ambrostoma quadriimpressum Motschulsky

    Directory of Open Access Journals (Sweden)

    Guolei Zhao

    2011-09-01

    Full Text Available A new phenylethyl alkyl amide, (10R-10-hydroxy-N-phenethyloctadecanamide (1, was isolated from the beetle Ambrostoma quadriimpressum Motschulsky. The structure of the amide was determined by NMR and MS. The absolute configuration of compound 1 was confirmed by an asymmetric total synthesis, which was started from L-glutamic acid. The construction of the aliphatic chain was accomplished by the selective protection of the hydroxy groups and two-time implementation of the Wittig olefination reaction.

  16. Alkylation of isobutane by butenes on zirconium sulfate catalysts

    International Nuclear Information System (INIS)

    Lavrenov, A.V.; Perelevskij, E.V.; Finevich, V.P.; Zajkovskij, V.I.; Paukshtis, E.A.; Duplyakiv, V.K.; Bal'zhinimaev, B.S.

    2003-01-01

    Preparation of applied zirconium sulfate catalysts obtained by the method of impregnation is investigated. Results of comparative study of structural, acid-base and catalytic properties of sulfated zirconium dioxide applied on silica gel and aluminium oxide are represented. Intervals of values of synthesis basic parameters and characteristics of catalysts properties providing achievement of high activity and selectivity in isobutane alkylation by butenes in liquid phase are determined [ru

  17. Effects of alkylating carcinogens on human tumor cells in culture

    International Nuclear Information System (INIS)

    Goth-Goldstein, R.; Hughes, M.

    1987-01-01

    In Escherichia coli 3-methyladenine and 3-methylguanine have been identified as lethal lesions, since two types of alkylating agent-sensitive mutants were deficient in repair of either of these lesions. Similar alkylation-sensitive human cell lines exist. These are the tumor cell lines of the complex Mer - phenotype. All Mer - cells examined were hypersensitive to killing by MNNG and other alkylating agents, and failed to repair O 6 -methylguanine. The widely studied HeLa S3 cell line has the Mer + phenotype, but a Mer - variant (HeLa MR) has arisen. This offers the possibility to study Mer - and Mer + cells of otherwise similar genetic background. We are using these two variants to analyze the Mer - phenotype further. When HeLa S3 and HeLa MR were treated with a highly dose of MNNG, and the surviving population exposed to a second dose of MNNG 2-3 weeks later, HeLa S3 (Mer + ) cells were equally or even slightly more sensitive to a second exposure of MNNG, whereas the surviving HeLa MR (Mer - ) population was much more resistant to MNNG. 1 fig., 1 tab

  18. Decreased stability of DNA in cells treated with alkylating agents

    Energy Technology Data Exchange (ETDEWEB)

    Frankfurt, O.S. (Cedars Medical Center, Miami, FL (United States))

    1990-12-01

    A modified highly sensitive procedure for the evaluation of DNA damage in individual cells treated with alkylating agents is reported. The new methodology is based on the amplification of single-strandedness in alkylated DNA by heating in the presence of Mg{sup 2+}. Human ovarian carcinoma cells A2780 were treated with nitrogen mustard (HN2), fixed in methanol, and stained with monoclonal antibody (MOAB) F7-26 generated against HN2-treated DNA. Binding of MOAB was measured by flow cytometry with indirect immunofluorescence. Intensive binding of MOAB to control and drug-treated cells was observed after heating in Tris buffer supplemented with MgCl{sub 2}. Thus, the presence of phosphates and MgCl{sub 2} during heating was necessary for the detection of HN2-induced changes in DNA stability. Fluorescence of HN2-treated cells decreased to background levels after treatment with single-strand-specific S{sub 1} nuclease. MOAB F7-26 interacted with single-stranded regions in DNA and did not bind to dsDNA or other cellular antigens. It is suggested that alkylation of guanines decreased the stability of the DNA molecule and increased the access of MOAB F7-26 to deoxycytidines on the opposite DNA strand.

  19. Chemotherapy-induced pulmonary hypertension: role of alkylating agents.

    Science.gov (United States)

    Ranchoux, Benoît; Günther, Sven; Quarck, Rozenn; Chaumais, Marie-Camille; Dorfmüller, Peter; Antigny, Fabrice; Dumas, Sébastien J; Raymond, Nicolas; Lau, Edmund; Savale, Laurent; Jaïs, Xavier; Sitbon, Olivier; Simonneau, Gérald; Stenmark, Kurt; Cohen-Kaminsky, Sylvia; Humbert, Marc; Montani, David; Perros, Frédéric

    2015-02-01

    Pulmonary veno-occlusive disease (PVOD) is an uncommon form of pulmonary hypertension (PH) characterized by progressive obstruction of small pulmonary veins and a dismal prognosis. Limited case series have reported a possible association between different chemotherapeutic agents and PVOD. We evaluated the relationship between chemotherapeutic agents and PVOD. Cases of chemotherapy-induced PVOD from the French PH network and literature were reviewed. Consequences of chemotherapy exposure on the pulmonary vasculature and hemodynamics were investigated in three different animal models (mouse, rat, and rabbit). Thirty-seven cases of chemotherapy-associated PVOD were identified in the French PH network and systematic literature analysis. Exposure to alkylating agents was observed in 83.8% of cases, mostly represented by cyclophosphamide (43.2%). In three different animal models, cyclophosphamide was able to induce PH on the basis of hemodynamic, morphological, and biological parameters. In these models, histopathological assessment confirmed significant pulmonary venous involvement highly suggestive of PVOD. Together, clinical data and animal models demonstrated a plausible cause-effect relationship between alkylating agents and PVOD. Clinicians should be aware of this uncommon, but severe, pulmonary vascular complication of alkylating agents. Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  20. Separation of products of alkylation of isobutane by olefins

    Energy Technology Data Exchange (ETDEWEB)

    Ward, J.

    1979-03-15

    The alkylation (A1) of isobutane (I) by propylene, butylene and amylenes is carried out at 24-52 degrees, pressure sufficient to maintain the liquid phase, and a molar ratio of I to olefins (O1) 10:1-15:1. The bulk ratio of catalysts to hydrocarbons in the reaction zone was 0.5:1-10:1; when using HF-K-T as the catalysts, it should contain less than 5 percent water and greater than or equal to 65 percent titrated HF. The hydrocarbon products (UP) from the alkylation zone are added after separating the catalyst in a fractionation tower; distillation is carried out at 38-49 degrees and 1.03-1.3 NPa. The head fraction containing I and less than 50 molar percent C3H8 and also fraction I at the point below the input side of the UP which contains less than 8 molar percent C3H8 and fraction n-C4H10 at the point below the point of discharge of fraction I is drained from the tower. The alkylate is discharged at the bottom of the tower. According to the patent the tower operates at low pressure. This improves relative volatility of individual components and reduces heat consumption. The best results are obtained when a head fraction or the concentration C3H8 approximately 25 molar percent is discharged.

  1. Terrestrial fate of coal-liquid constituents: behavior of alkyl anilines in soil

    Energy Technology Data Exchange (ETDEWEB)

    Felice, L.J.; Zachara, J.M.; Rogers, J.E.

    1982-07-01

    The low molecular weight aromatic amines (anilines) are important water soluble constituents of coal liquids. The impact of anilines released to the terrestrial environment will largely depend on their mobility and persistence. Studies were conducted to investigate those processes governing the mobility and persistence of the alkylanilines, namely, soil sorption and chemical/microbial degradation. Soil sorption measurements were conducted on aniline and several methyl substituted anilines on A and B horizons of a soil profile collected from Davies County, Kentucky. The magnitude of sorption was large in all horizons. Sorption in the B horizons was larger than in the A horizon for many of the anilines studied, indicating the importance of both the mineral matrix and organic carbon content of the soil in determining the magnitude of sorption. Results of these measurements indicate that movement of the anilines through the soil would be significantly attenuated by sorption reactions. Aniline sorption measurement in the A horizon after removal of the organic matter and in the B/sub 22/ horizon after removal of amorphous iron oxides and crystalline iron oxides indicate that organic matter largely controls aniline sorption in the A horizon, while crystalline iron oxides and phyllosilicates are important in the B horizons. The effects of pH on aniline sorption was also examined and shown to have significant effects on the magnitude of sorption in both A and B horizons. Soil degradation studies using /sup 14/C-3-methylaniline as a model for alkyl aniline degradation show that 3-methylaniline is readily metabolized by soil microorganisms during the 32-day period examined.

  2. Total Syntheses of Polycyclic Polyprenylated Acylphloroglucinol Natural Products and Analogs Utilizing Alkylative Dearomatizations and Cationic Cyclizations

    Science.gov (United States)

    Boyce, Jonathan H.

    Polycyclic polyprenylated acylphloroglucinols (PPAPs) are structurally complex natural products with promising biological activities. These compounds have interesting anticancer and anti-HIV properties as well as other biological activities making them highly attractive synthetic targets. We report a stereodivergent, asymmetric total synthesis of (-)-clusianone in six steps from commercial materials. We have implemented a challenging cationic cyclization forging a bond between two sterically encumbered quaternary carbon atoms. Mechanistic studies point to the unique ability of formic acid to mediate the cyclization forming the clusianone framework. We also present a biosynthesis-inspired, diversity-oriented synthesis approach for rapid construction of PPAP analogs via palladium-catalyzed dearomative conjunctive allylic alkylation (DCAA). These efficient palladium-catalyzed protocols construct the [3.3.1]-bicyclic PPAP core in a single step from their stable aromatic precursors. The first syntheses of 13,14-didehydroxyisogarcinol and garcimultiflorone A stereoisomers are reported in six steps from a commercially available phloroglucinol. Lewis acid-controlled, diastereoselective cationic oxycyclizations enabled asymmetric syntheses of (-)-6-epi-13,14-didehydroxyisogarcinol and (+)-30-epi-13,14-didehydroxyisogarcinol. A similar strategy enabled production of the meso-derived isomers (+/-)-6,30- epi-13,14-didehydroxyisogarcinol and (+/-)-6,30-epi -garcmultiflorone A. A convenient strategy for gram scale synthesis of these stereoisomers was developed utilizing diastereomer separation at a later stage in the synthesis that minimized the number of necessary synthetic operations to access all possible stereoisomers. Finally, we report cationic rearrangements of dearomatized acylphloroglucinols leading to the formation of unprecedented PPAP scaffolds. A novel type A [3.3.1]-bicyclic PPAP was produced as a major product and the structure confirmed by X-ray crystallographic

  3. UV absorption spectra, kinetics and mechanism for alkyl and alkyl peroxy radicals originating from t-butyl alcohol

    DEFF Research Database (Denmark)

    Langer, S.; Ljungström, E.; Sehested, J.

    1994-01-01

    Alkyl and alkyl peroxy radicals from 1-butyl alcohol (TBA), HOC (CH3)2CH2. and HOC(CH3)2CH2O2. have been studied in the ps phase at 298 K. Two techniques were used: pulse radiolysis UV absorption to measure the spectra and kinetics, and long path-length Fourier transform infrared spectroscopy (FTIR......) and k(HOC(CH3)2CH2O2. + NO2) were determined to be (4.9 +/- 0.9) X 10(-12) and (6.7 +/- 0.9) x 10(-12) cm3 molecule-1 s-1, respectively. In the FTIR experiments products were studied using chlorine-initiated oxidation in TBA/N2/Cl2 and TBA/N2/O2/Cl2 mixtures....

  4. Glutamine deficiency induces DNA alkylation damage and sensitizes cancer cells to alkylating agents through inhibition of ALKBH enzymes.

    Science.gov (United States)

    Tran, Thai Q; Ishak Gabra, Mari B; Lowman, Xazmin H; Yang, Ying; Reid, Michael A; Pan, Min; O'Connor, Timothy R; Kong, Mei

    2017-11-01

    Driven by oncogenic signaling, glutamine addiction exhibited by cancer cells often leads to severe glutamine depletion in solid tumors. Despite this nutritional environment that tumor cells often experience, the effect of glutamine deficiency on cellular responses to DNA damage and chemotherapeutic treatment remains unclear. Here, we show that glutamine deficiency, through the reduction of alpha-ketoglutarate, inhibits the AlkB homolog (ALKBH) enzymes activity and induces DNA alkylation damage. As a result, glutamine deprivation or glutaminase inhibitor treatment triggers DNA damage accumulation independent of cell death. In addition, low glutamine-induced DNA damage is abolished in ALKBH deficient cells. Importantly, we show that glutaminase inhibitors, 6-Diazo-5-oxo-L-norleucine (DON) or CB-839, hypersensitize cancer cells to alkylating agents both in vitro and in vivo. Together, the crosstalk between glutamine metabolism and the DNA repair pathway identified in this study highlights a potential role of metabolic stress in genomic instability and therapeutic response in cancer.

  5. High-field FT-ICR-MS and aromaticity equivalent approach for structural identification of water soluble organic compounds (WSOC)

    Science.gov (United States)

    Harir, Mourad; Yassine, Mahmoud M.; Dabek-Zlotorzynska, Ewa; Hertkorn, Norbert; Schmitt-Kopplin, Philippe

    2015-04-01

    identification and characterization of aromatic and condensed aromatic compounds in WSOC [2]. We proposed threshold values of Xc≥ 2.5000 and Xc≥ 2.7143 as ambiguous minimum criteria for the presence of aromatic structure and condensed aromatic compounds, respectively. The advantage of employing this parameter is that Xc would have a constant value for each proposed core structure regardless the degree of alkylation, and thus visual representation and structural interpretations of the spectra become advantageous for characterizing and comparing complex samples. Diesel particulate matter (DPM) and two atmospheric aerosols collected in the industrial area affected by biomass burning events were used to study the applicability of the proposed criteria for the improved identification of aromatic and condensed aromatic structures in complex mixtures in the FT-ICR mass spectra. References [1] Koch.BP, Dittmar.T. From mass to structure: an aromaticity index for high-resolution mass data of natural organic matter. Rapid Commun. Mass Spectrom. 2006, 20, 926-932 [2] Yassine.MM, Harir.M, Dabek-Zlotorzynska.E, Schmitt-Kopplin.Ph. Structural characterization of organic aerosol using Fourier transform ion cyclotron resonance mass spectrometry: Aromaticity equivalent approach. Rapid Commun. Mass Spectrom. 2014. 28. 2445-2454

  6. Glutamine deficiency induces DNA alkylation damage and sensitizes cancer cells to alkylating agents through inhibition of ALKBH enzymes

    OpenAIRE

    Tran, Thai Q.; Ishak Gabra, Mari B.; Lowman, Xazmin H.; Yang, Ying; Reid, Michael A.; Pan, Min; O’Connor, Timothy R.; Kong, Mei

    2017-01-01

    Driven by oncogenic signaling, glutamine addiction exhibited by cancer cells often leads to severe glutamine depletion in solid tumors. Despite this nutritional environment that tumor cells often experience, the effect of glutamine deficiency on cellular responses to DNA damage and chemotherapeutic treatment remains unclear. Here, we show that glutamine deficiency, through the reduction of alpha-ketoglutarate, inhibits the AlkB homolog (ALKBH) enzymes activity and induces DNA alkylation damag...

  7. Efficient synthesis of N-alkyl-2,7-dihalocarbazoles by simultaneous carbazole ring closure and N-alkylation

    Czech Academy of Sciences Publication Activity Database

    Výprachtický, Drahomír; Kmínek, Ivan; Pokorná, Veronika; Cimrová, Věra

    2012-01-01

    Roč. 68, č. 25 (2012), s. 5075-5080 ISSN 0040-4020 R&D Projects: GA MŠk(CZ) 1M06031; GA ČR GAP106/12/0827 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : carbazole ring closure * carbazole alkylation * heterocycles Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.803, year: 2012

  8. Balancing repair and tolerance of DNA damage caused by alkylating agents.

    Science.gov (United States)

    Fu, Dragony; Calvo, Jennifer A; Samson, Leona D

    2012-01-12

    Alkylating agents constitute a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER) and mismatch repair (MMR), respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for a favourable response of an organism to alkylating agents. Furthermore, the response of an individual to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity.

  9. Chemotaxis of Azospirillum species to aromatic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-de-Victoria, G.; Lovell, C.R. (Univ. of South Carolina, Columbia, SC (United States))

    1993-09-01

    Azospirillum sspeciesare free-living nitrogen fixing bacteria commonly found in soils and in association with plant roots, including important agricultural crops. Rhizosphere colonization my Azospirillum species has been shown to stimulate growth of a variety of plant species. Chemotaxis is one of the properties which may contribute to survival, rhizosphere colonization and the initiation of mutualistic interactions by Azospirillum species. This study evaluates the chemotactic responses of three Azospirillum stains to a variety of aromatic compounds:benzoate, catechol, 4-HB, and PCA. Results indicate that the same aromatic substance can elicit different chemotactic responses from different Azospirillum species, and that Azospirillum can detect aromatic substrates at concentrations similar to those they encounter naturally. 36 refs., 1 fig., 6 tabs.

  10. Ion beam irradiation effects on aromatic polymers

    International Nuclear Information System (INIS)

    Shukushima, Satoshi; Ueno, Keiji

    1995-01-01

    We studied the optical and thermal properties of aromatic polymer films which had been irradiated with 1 MeV H + , H 2 + and He + ions. The examined aromatic polymers were polyetherether ketone(PEEK), polyetherimide(PEI), polyether sulfon(PES), polysulfon(PSF), and polyphenylene sulfide(PPS). The optical densities at 300nm of PES and PSF greatly increased after the irradiation. The optical densities at 400nm of all the examined polymer lineally increased with the irradiation dose. The PEEK film which had been irradiated with 1 MeV H + was not deformed above melting point. This demonstrates that cross-linking occurs in PEEK films by ion beam irradiation. As for the effects, depending on the mass of the irradiated ions, it was found that the ions with a high mass induced larger effects on the aromatic polymers for the same absorption energy. (author)

  11. Cytotoxicity of alkylating agents towards sensitive and resistant strains of Escherichia coli in relation to extent and mode of alkylation of cellular macromolecules and repair of alkylation lesions in deoxyribonucleic acids.

    Science.gov (United States)

    Lawley, P D; Brookes, P

    1968-09-01

    1. A quantitative study was made of the relationship between survival of colony-forming ability in Escherichia coli strains B/r and B(s-1) and the extents of alkylation of cellular DNA, RNA and protein after treatment with mono- or di-functional sulphur mustards, methyl methanesulphonate or iodoacetamide. 2. The mustards and methyl methanesulphonate react with nucleic acids in the cells, in the same way as found previously from chemical studies in vitro, and with proteins. Iodoacetamide reacts only with protein, principally with the thiol groups of cysteine residues. 3. The extents of alkylation of cellular constituents required to prevent cell division vary widely according to the strain of bacteria and the nature of the alkylating agent. 4. The extents of alkylation of the sensitive and resistant strains at a given dose of alkylating agent do not differ significantly. 5. Removal of alkyl groups from DNA of cells of the resistant strains B/r and 15T(-) after alkylation with difunctional sulphur mustard was demonstrated; the product di(guanin-7-ylethyl) sulphide, characteristic of di- as opposed to mono-functional alkylation, was selectively removed; the time-scale of this effect suggests an enzymic rather than a chemical mechanism. 6. The sensitive strain B(s-1) removed alkyl groups from DNA in this way only at very low extents of alkylation. When sensitized to mustard action by treatment with iodoacetamide, acriflavine or caffeine, the extent of alkylation of cellular DNA corresponding to a mean lethal dose was decreased to approximately 3 molecules of di(guanin-7-ylethyl) sulphide in the genome of this strain. 7. Relatively large numbers of monofunctional alkylations per genome can be withstood by this sensitive strain. Iodoacetamide had the weakest cytotoxic action of the agents investigated; methyl methanesulphonate was significantly weaker in effect than the monofunctional sulphur mustard, which was in turn weaker than the difunctional sulphur mustard. 8

  12. Highly enantio- and diastereoselective allylic alkylation of Morita-Baylis-Hillman carbonates with allyl ketones

    KAUST Repository

    Tong, Guanghu

    2013-05-17

    The asymmetric allylic alkylation of Morita-Baylis-Hillman (MBH) carbonates with allyl ketones has been developed. The α-regioselective alkylation adducts, containing a hexa-1,5-diene framework with important synthetic value, were achieved in up to 83% yield, >99% ee, and 50:1 dr by using a commercially available Cinchona alkaloid as the catalyst. From the allylic alkylation adduct, a cyclohexene bearing two adjacent chiral centers was readily prepared. © 2013 American Chemical Society.

  13. Effects of Photo-chemically Activated Alkylating Agents of the FR900482 Family on Chromatin

    OpenAIRE

    Subramanian, Vidya; Ducept, Pascal; Williams, Robert M.; Luger, Karolin

    2007-01-01

    Bioreductive alkylating agents are an important class of clinical antitumor antibiotics that cross-link and mono-alkylate DNA. Here we use a synthetic photochemically activated derivative of FR400482 to investigate the molecular mechanism of this class of drugs in a biologically relevant context. We find that the organization of DNA into nucleosomes effectively protects it against drug-mediated cross-linking, while permitting mono-alkylation. This modification has the potential to form covale...

  14. Protonation of 1-alkyl-2-allyllithium-0-carboranes and 1-methyl-2-allylmaonesium chloride-0-carborane

    International Nuclear Information System (INIS)

    Ivanova, N.N.; Kazantsev, A.V.; Zakharkin, L.I.

    1975-01-01

    The ratio of 1-alkyl-2-allyl and 1-alkyl-2-propenyl-0-carboranes generated in protonation of 1-alkyl-2-lithium allyl-0-carboranes with various protolytic agents in ether, THF and liquid ammonia depends on the nature of protolytic agent and solvent. The rat:o of these allyl and propenyl isomers is also affected by steric effects of the protolytic agent and 0-carborane nucleus

  15. Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters

    Directory of Open Access Journals (Sweden)

    Yoshinori Yamamoto

    2011-05-01

    Full Text Available Unprecedented alkylation of silyl enol ethers has been developed by the use of ortho-alkynylbenzoic acid alkyl esters as alkylating agents in the presence of a gold catalyst. The reaction probably proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack on the silyl enol ethers. The generated leaving compound abstracts a proton to regenerate the silyl enol ether structure.

  16. Quantum molecular modeling of the interaction between guanine and alkylating agents--2--nitrogen mustard.

    Science.gov (United States)

    Hamza, A; Broch, H; Vasilescu, D

    1996-06-01

    The alkylation mechanism of guanine by nitrogen mustard (HN2) was studied by using a supermolecular modeling at the ab initio 6-31G level. Our computations show that interaction of guanine with the aziridinium form of HN2 necessitates a transition state for the N7 alkylation route. The pathway of N7-guanine alkylation by nitrogen and sulfur mustards is discussed on the basis of the Molecular Electrostatic Potential and HOMO-LUMO properties of these molecules.

  17. Balancing repair and tolerance of DNA damage caused by alkylating agents

    OpenAIRE

    Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D.

    2012-01-01

    Alkylating agents constitute a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER) and mismatch repair (MMR), respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial ...

  18. SERIES: Genomic instability in cancer Balancing repair and tolerance of DNA damage caused by alkylating agents

    OpenAIRE

    Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D

    2012-01-01

    Alkylating agents comprise a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER), and mismatch repair (MMR) respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial fo...

  19. Hydride Transfer versus Deprotonation Kinetics in the Isobutane–Propene Alkylation Reaction: A Computational Study

    OpenAIRE

    Liu, Chong; van Santen, Rutger A.; Poursaeidesfahani, Ali; Vlugt, Thijs J. H.; Pidko, Evgeny A.; Hensen, Emiel J. M.

    2017-01-01

    The alkylation of isobutane with light alkenes plays an essential role in modern petrochemical processes for the production of high-octane gasoline. In this study we have employed periodic DFT calculations combined with microkinetic simulations to investigate the complex reaction mechanism of isobutane–propene alkylation catalyzed by zeolitic solid acids. Particular emphasis was given to addressing the selectivity of the alkylate formation versus alkene formation, which requires a high rate o...

  20. Global aromatics supply. Today and tomorrow

    Energy Technology Data Exchange (ETDEWEB)

    Bender, M. [BASF SE, Ludwigshafen (Germany)

    2013-11-01

    Aromatics are the essential building blocks for some of the largest petrochemical products in today's use. To the vast majority they are consumed to produce intermediates for polymer products and, hence, contribute to our modern lifestyle. Their growth rates are expected to be in line with GDP growth in future. This contrasts the significantly lower growth rates of the primary sources for aromatics - fuel processing and steam cracking of naphtha fractions. A supply gap can be expected to open up in future for which creative solutions will be required. (orig.)

  1. Three-dimensional aromaticity of polyhedral boranes

    International Nuclear Information System (INIS)

    Aihara, J.

    1978-01-01

    Resonance energies of typical polyhedral boranes with a general formula of B/sub n/H/sub n/ 2- have been calculated by means of a graph-theoretical theory of aromaticity previously reported by Aihara. Huckel-type molecular orbitals employed are those of Kettle and Tomlinson with three-center BBB localized orbitals as basis functions. Most polyhedral boranes investigated are predicted to be aromatic with positive resonance energies, in general agreement with their chemistry. The present resonance energy is fairly proportional to the logarithm of the number of valence structures allowed for the polyhedral borane

  2. Methods for the nitration of aromatic compounds

    OpenAIRE

    Smith, Keith; Alotaibi, Mohammad Hayal; El-Hiti, Gamal A.

    2012-01-01

    According to the invention there is provided a method for the nitration of an aromatic compound including the step of reacting the aromatic compound with nitric acid in the presence of an acid anhydride and an aluminosilicate catalyst, in which the acid anhydride is at least one of: ((CnH2n+1)CO)20, where n is 1 to 4 and the moiety CnH2n+1 can be straight or branched chain; ((CHpClq)CO)20, where p is 0 to 2, q is 1 to 3, and p+q = 3; and oxoiane -2, 5-dione, with the proviso that when the aci...

  3. Production of aromatics from di- and polyoxygenates

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Taylor; Blank, Brian; Jones, Casey; Woods, Elizabeth; Cortright, Randy

    2016-08-02

    Methods, catalysts, and reactor systems for producing in high yield aromatic chemicals and liquid fuels from a mixture of oxygenates comprising di- and polyoxygenates are disclosed. Also disclosed are methods, catalysts, and reactor systems for producing aromatic chemicals and liquid fuels from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like; and methods, catalysts, and reactor systems for producing the mixture of oxygenates from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like. The disclosed catalysts for preparing the mixture of oxygenates comprise a Ni.sub.nSn.sub.m alloy and a crystalline alumina support.

  4. Production of aromatics from di- and polyoxygenates

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Taylor; Blank, Brian; Jones, Casey; Woods, Elizabeth; Cortright, Randy

    2016-09-13

    Methods, catalysts, and reactor systems for producing in high yield aromatic chemicals and liquid fuels from a mixture of oxygenates comprising di- and polyoxygenates are disclosed. Also disclosed are methods, catalysts, and reactor systems for producing aromatic chemicals and liquid fuels from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like; and methods, catalysts, and reactor systems for producing the mixture of oxygenates from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like. The disclosed catalysts for preparing the mixture of oxygenates comprise a Group VIII metal and a crystalline alumina support.

  5. Production of aromatics from di- and polyoxygenates

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Taylor; Blank, Brian; Jones, Casey; Woods, Elizabeth; Cortright, Randy

    2017-07-04

    Methods, catalysts, and reactor systems for producing in high yield aromatic chemicals and liquid fuels from a mixture of oxygenates comprising di- and polyoxygenates are disclosed. Also disclosed are methods, catalysts, and reactor systems for producing aromatic chemicals and liquid fuels from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like; and methods, catalysts, and reactor systems for producing the mixture of oxygenates from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like. The disclosed catalysts for preparing the mixture of oxygenates comprise a Ni.sub.nSn.sub.m alloy and a crystalline alumina support.

  6. Thermal stability of the aromatic fraction of Safaniya crude oil (Middle East): experimental study, kinetic scheme by molecular classes and geochemical implications; Stabilite thermique de la fraction aromatique de l'huile brute safaniya (Moyen-Orient): etude experimentale, schema cinetique par classes moleculaires et implications geochimiques

    Energy Technology Data Exchange (ETDEWEB)

    Al Darouich, T.

    2005-07-15

    The thermal evolution of reservoir oils is controlled by the kinetics of cracking reactions. The present work is concerned with the study of the thermal stability of the light aromatic components (C{sub 6}-C{sub 14}) of crude oils under geological conditions. The aim is to predict this stability through a mode l derived from laboratory pyrolyses. The light cut < 250 deg. C of Safaniya crude oil, corresponding to the C{sub 15} components, was obtained by fractionated distillation; pure aromatic fraction was then separated by liquid chromatography. Detailed molecular characterisation of the aromatic fraction was acquired using HPLC, GC and GC/MS. Then, quantified individual aromatic compounds were lumped into six molecular classes: BTXN, methyl-aromatics, alkyl-aromatics, naphthenic-aromatics, indene and sulphur - containing aromatics. Pyrolyses of the aromatic fraction were performed in gold tubes at 100 bars and different temperature/time conditions in a wide range (1 to 93%) of global conversion. Pyrolysis effluents were analysed and lumped into classes. The pyrolysis data were used to elaborate a semi - empirical kinetic scheme of 13 stoichiometric reactions for the primary and secondary cracking of the unstable classes. The scheme kinetic parameters were first estimated, and then numerically optimised, with the constraints of mass balance and hydrogen conservation. A set of pyrolysis experiments was performed at 375 deg.C under high pressures: 400, 800 and 1200 bars. Increasing slowing down in conversion rate with increasing pressure was thus observed compared to experiments at 100 bars. A slight selective effect of pressure on the different aromatic classes of the charge and on the product distribution was evidenced. The extrapolation of the kinetic model to the conditions of Elgin Field (North Sea) showed that pressure effect should shift the thermal cracking of light aromatics to higher temperatures by almost 8 deg. C. (author)

  7. Methods of producing alkylated hydrocarbons from an in situ heat treatment process liquid

    Science.gov (United States)

    Roes, Augustinus Wilhelmus Maria [Houston, TX; Mo, Weijian [Sugar Land, TX; Muylle, Michel Serge Marie [Houston, TX; Mandema, Remco Hugo [Houston, TX; Nair, Vijay [Katy, TX

    2009-09-01

    A method for producing alkylated hydrocarbons is disclosed. Formation fluid is produced from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. The liquid stream is fractionated to produce at least a second gas stream including hydrocarbons having a carbon number of at least 3. The first gas stream and the second gas stream are introduced into an alkylation unit to produce alkylated hydrocarbons. At least a portion of the olefins in the first gas stream enhance alkylation.

  8. Conversion of alkyl radicals to allyl radicals in irradiated single crystal mats of polyethylene

    International Nuclear Information System (INIS)

    Fujimura, T.; Hayakawa, N.; Kuriyama, I.

    1978-01-01

    The decay of alkyl radicals, the conversion of alkyl radicals to allyl radicals and the trapping of allyl radicals in irradiated single crystal mats of polyethylene have been studied by electron spin resonance (e.s.r.). It has been suggested that in the crystal core alkyl radicals react with trans-vinylene double bonds and are converted into trans-vinylene allyl radicals; at the crystal surface, alkyl radicals react with vinyl end groups and are converted into allyl radicals with vinyl end groups. The decay of radical pairs and the formation of trans-vinylene double bonds are discussed. (author)

  9. Liquid phase alkylation of anisole and phenol catalyzed by niobium phosphate

    OpenAIRE

    Pereira, Cynthia C. M.; de la Cruz, Marcus H. C.; Lachter, Elizabeth R.

    2010-01-01

    The catalytic activity of niobium phosphate was evaluated in the liquid phase alkylation reaction of anisole with 1-dodecene, 1- octene, 2-octanol and 1-octen-3-ol and in the reaction of phenol with 1-octen-3-ol. Best results were achieved in the alkylation of anisole and phenol with 1-octen-3-ol that produced mainly monoalkylate products. In the reaction with phenol the major products formed were octenylphenols (C-alkylation) and phenyl-octenyl ether (O-alkylates). The reaction favors the fo...

  10. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    Science.gov (United States)

    Smith, R.E.; Dolbeare, F.A.

    1980-10-21

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes. No Drawings

  11. Indium-silver- and zinc-silver-mediated barbier-grignard-type alkylation reactions of imines by using unactivated alkyl halides in aqueous media.

    Science.gov (United States)

    Shen, Zhi-Liang; Cheong, Hao-Lun; Loh, Teck-Peng

    2008-01-01

    In the presence of In or Zn/AgI/InCl(3), an efficient and practical method for the Barbier-Grignard-type alkylation reactions of simple imines by using a one-pot condensation of various aldehydes, amines (including the aliphatic and chiral version), and secondary alkyl iodides has been developed. The reaction proceeded more efficiently in water than in organic solvents. Without the use of CuI, it mainly gave the imine self-reductive coupling product, which was not the alkylated product. Good diastereoselectivities (up to 92:8 dr) were obtained when L-valine methyl ester was used as the substrate.

  12. Remediation of soil contaminated with polycyclic aromatic ...

    African Journals Online (AJOL)

    user

    2011-02-14

    Feb 14, 2011 ... adverse situations not only affect the ecosystem adver- sely as plant and animals may not survive, the crude may also contain varying levels of polycyclic aromatic hydrocarbons ..... Mechanism of phytoremediation: Biochemical and ecological interaction between plants and bacteria. Environ. Rev. 6: 65- 79.

  13. Toxic Potential of Carcinogenic Polycyclic Aromatic Hydrocarbons ...

    African Journals Online (AJOL)

    DR. GODSON

    Toxic Potential of Carcinogenic Polycyclic Aromatic Hydrocarbons (cPAHs) and Heavy. Metal in Crude Oil from Gokana Area, Rivers ... Exploration and production activities of petroleum in the Niger delta, Nigeria has led to the accidental ..... Chemical and bio-geophysical impact of four- dimensional seismic exploration.

  14. Polycyclic aromatic hydrocarbons (PAHs) contamination in coastal ...

    African Journals Online (AJOL)

    The objective of this study was to determine the levels of polycyclic aromatic hydrocarbons (PAHs) in sediments and crabs in the mangrove ecosystems of Zanzibar. Sediments and crabs from eight sampling sites were analysed for eleven selected PAHs. Samples were extracted with dichloromethane by ultrasonication, ...

  15. Determination of carcinogenic polycyclic aromatic hydrocarbons in ...

    African Journals Online (AJOL)

    Determination of carcinogenic polycyclic aromatic hydrocarbons in air samples in Irbid, north Jordan. A Al-Gawadreh Sat, M.B. Gasim, A.R. Hassan, A Azid. Abstract. Air samples were collected at an urban site and a rural (BERQESH) site during February (2017) until March (2017) to determine concentrations of polycyclic ...

  16. Measurements of Polycyclic Aromatic Hydrocarbons and ...

    African Journals Online (AJOL)

    ... with both fluorescence and ultraviolet detection. The genotoxicity was investigated by means of two bacterial assays: the Ames test and the SOS Chromotest. A number of PAHs were identified and genotoxic activity was observed in both of the assays. Keywords: Polycyclic aromatic hydrocarbons, toll plaza, genotoxicity.

  17. Fate and biodegradability of sulfonated aromatic amines

    NARCIS (Netherlands)

    Tan, N.C.G.; Leeuwen, van A.; Voorthuizen, van E.M.; Slenders, P.; Prenafeta, F.X.; Temmink, H.; Lettinga, G.; Field, J.A.

    2005-01-01

    Ten sulfonated aromatic amines were tested for their aerobic and anaerobic biodegradability and toxicity potential in a variety of environmental inocula. Of all the compounds tested, only two aminobenzenesulfonic acid (ABS) isomers, 2- and 4-ABS, were degraded. The observed degradation occurred only

  18. arene derivatives containing multiple aromatic groups

    Indian Academy of Sciences (India)

    ... two novel thiacalix[4]arene derivatives containing multiple aromatic groups in yields of 86% and 90%. Their complexation properties for four organic dyes were investigated by liquid-liquid extraction experiments, complexation UV-Vis spectra and mass spectrum. The highest extraction percentage was 97% for Neutral red.

  19. Determination of polynuclear aromatic hydrocarbons (PAHs) in ...

    African Journals Online (AJOL)

    Several water bodies in the Niger Delta region of Nigeria where extensive crude oil production activities take place were analyzed for the presence of 16 US EPA priority polynuclear aromatic hydrocarbons (PAHs) namely: naphthalene, acenaphthylene, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene, ...

  20. Adsorption of polynuclear aromatic hydrocarbons from aqueous

    African Journals Online (AJOL)

    ABSTRACT. The adsorption efficiency of a new hybrid clay adsorbent for polynuclear aromatic hydrocarbons. (PAHs) is compared with known modified clay adsorbents. The new hybrid clay adsorbent (HYCA) showed far higher adsorption capacities for the adsorption of various PAH molecules compared with sodium ...

  1. Predicting the Biodegradation of Polycyclic Aromatic Hydrocarbons ...

    African Journals Online (AJOL)

    ... the concentrations of the polycyclic aromatic hydrocarbons, and this was followed by a 'plateau' concentration signifying the attainment of endpoint of the degradation process. Keywords: Model, Neuron, Feed forward, Training, Input, Hidden and Output layers. Journal of the Nigerian Association of Mathematical Physics, ...

  2. Aromatic cytokinins in micropropagated potato plants

    Czech Academy of Sciences Publication Activity Database

    Baroja, F. E.; Aguirreolea, J.; Martínková, Hana; Hanuš, Jan; Strnad, Miroslav

    2002-01-01

    Roč. 40, č. 3 (2002), s. 217-224 ISSN 0981-9428 R&D Projects: GA MŠk OC 844.10; GA ČR GA301/02/0475 Institutional research plan: CEZ:AV0Z5038910 Keywords : Acclimatization * Aromatic cytokinins * Micropropagation Subject RIV: CE - Biochemistry Impact factor: 1.582, year: 2002

  3. Remediation of soil contaminated with polycyclic aromatic ...

    African Journals Online (AJOL)

    The aim of this study was to determine ways of remediating soils contaminated with polycyclic aromatic hydrocarbons (PAHs) associated with crude oil. The study involves the use of planted cowpeas, mushrooms, algae, dead vegetable and live earthworm, and fire-heating of the contaminated garden soil collected from the ...

  4. (Tpec) of Carcinogenic Polycyclic Aromatic Hydrocarbons (Cpahs)

    African Journals Online (AJOL)

    The aim of this paper is to report the determination of Total potency equivalent concentration (TPEC) of Carcinogenic polycyclic aromatic hydrocarbons (cPAHs) in soil samples from Bodo area in Ogoniland using the Toxicity Equivalent Factor (TEF) model. Gas Chromatography GC HP 5870 with FID was used for analysis.

  5. short communication aliphatic and polycyclic aromatic hydrocarbons ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. The impact of sunlight on aliphatic and polycyclic aromatic hydrocarbons profiles of Agbabu natural bitumen in Nigeria was investigated. The raw flow type of the bitumen was purified and exposed to sunlight for six consecutive months. Different portions of the bitumen were withdrawn at an interval of one.

  6. Polycyclic aromatic hydrocarbons (PAHs) degradation by laccase ...

    African Journals Online (AJOL)

    Laccase enzyme was produced from an isolate of the white rot fungus, Ganoderma lucidum Chaaim-001 BCU. The enzyme was subsequently evaluated for its degradative ability towards sixteen types of polycyclic aromatic hydrocarbons (PAHs). The G. lucidum laccase degraded antracene completely with or without a ...

  7. Fused aromatic thienopyrazines: structure, properties and function

    KAUST Repository

    Mondal, Rajib

    2010-01-01

    Recent development of a fused aromatic thieno[3.4-b]pyrazine system and their application in optoelectronic devices are reviewed. Introduction of a fused aromatic unit followed by side chain engineering, dramatically enhanced the charge carrier mobility in thin film transistor devices and mobilities up to 0.2 cm2/Vs were achieved. The optoelectronic properties of these fused aromatic thienopyrazine polymers (Eg = 1.3 to 1.6 eV, HOMO = -4.9 to -5.2 V) were tuned by introduction of various fused aromatic rings within thienopyrazine. By balancing the fundamental properties of these polymers, both high charge carrier mobilities and moderate PCEs in solar cells were achieved. Further, effects of copolymerizing units are discussed. Low band gap semiconducting polymer (Eg ∼ 1 eV) with high field effect mobility (0.044 cm2/Vs) was obtained using cyclopentadithiophene as copolymerizing unit. Finally, a molecular design approach to enhance the absorption coefficients is discussed, which resulted in improved power conversion efficiency in bulk heterojunction solar cells. © 2010 The Royal Society of Chemistry.

  8. Bioremediation of Polycyclic Aromatic Hydrocarbon contaminated ...

    African Journals Online (AJOL)

    This study investigates the effect of lead and chromium on the rate of bioremediation of polycyclic aromatic hydrocarbon (PAH) contaminated clay soil. Naphthalene was used as a target PAH. The soil was sterilized by heating at 120oC for one hour. 100g of the soil was contaminated with lead, chromium, nickel and mercury ...

  9. Synthesis and evaluation of aromaticity and tautomerization of ...

    Indian Academy of Sciences (India)

    Nurettin Menges

    FIPC-NICS and HOMA aromaticity indexes and it was observed that aromaticity of pyridazin(on)es was amenable to aromaticity of pyrazole and vice versa. Some tautomeric forms of pyridazinone were analyzed and the localized orbital locator maps, electron density maps, Fuzzy, Laplacian, and Mayer bond order methods.

  10. Genetic diversity in grain quality and nutrition of aromatic rices

    African Journals Online (AJOL)

    STORAGESEVER

    2009-04-06

    Apr 6, 2009 ... The study was conducted at Bangladesh Rice Research Institute (BRRI), Gazipur in 2005 to assess the genetic divergence of aromatic rices for ... aromatic rices, requires its collection and evaluation of existing cultivars of ...... (2002). Genetic divergence in aromatic rice (Oryza sativa L). Nat. J. Plant Improv.

  11. 40 CFR 721.2673 - Aromatic epoxide resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic epoxide resin (generic). 721... Substances § 721.2673 Aromatic epoxide resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic epoxide resin (PMN P...

  12. 40 CFR 721.5762 - Aromatic aldehyde phenolic resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic aldehyde phenolic resin... Specific Chemical Substances § 721.5762 Aromatic aldehyde phenolic resin (generic). (a) Chemical substance... aromatic aldehyde phenolic resin (PMN P-01-573) is subject to reporting under this section for the...

  13. Oil spill off the coast of Guimaras Island, Philippines: Distributions and changes of polycyclic aromatic hydrocarbons in shellfish.

    Science.gov (United States)

    Uno, Seiichi; Kokushi, Emiko; Añasco, Nathaniel C; Iwai, Takenori; Ito, Kazuki; Koyama, Jiro

    2017-11-30

    The sinking of the Solar 1 tanker caused serious heavy oil pollution around Guimaras Island, Philippines. In the present study, variations of parent polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs (alkPAHs) in some shellfish were investigated around Guimaras Island and other small islands from 3months to 5years after the spill. The total PAHs and alkPAHs in shellfish were detected in high concentrations at 448 and 33,666ng/g dry weight, respectively, in November 2006. The concentrations of alkPAHs gradually decreased, while the parent PAHs in shellfish degraded more slowly than the alkPAHs, which was likely due to the persistent characteristics of PAHs. The risks based on European Union regulations were insignificant in 2008, but total PAHs in shellfish were still over 8 times higher at the investigated sites in November 2011 than that before the oil spill. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Monomers for thermosetting and toughening epoxy resins. [glycidyl amine derivatives, propargyl-containing amines, and mutagenic testing of aromatic diamines

    Science.gov (United States)

    Pratt, J. R.

    1981-01-01

    Eight glycidyl amines were prepared by alkylating the parent amine with epichlorohydrin to form chlorohydrin, followed by cyclization with aqueous NaOH. Three of these compounds contained propargyl groups with postcuring studies. A procedure for quantitatively estimating the epoxy content of these glycidyl amines was employed for purity determination. Two diamond carbonates and several model propargly compounds were prepared. The synthesis of three new diamines, two which contain propargyloxy groups, and another with a sec-butyl group is in progress. These materials are at the dinitro stage ready for the final hydrogenation step. Four aromatic diamines were synthesized for mutagenic testing purposes. One of these compounds rapidly decomposes on exposure to air.

  15. Treatment of Perfluorinated Alkyl Substances in Wash Water ...

    Science.gov (United States)

    Report The U.S. Environmental Protection Agency’s (EPA) National Homeland Security Research Center partnered with the Idaho National Laboratory (INL) to build the Water Security Test Bed (WSTB) at the INL test site outside of Idaho Falls, Idaho. This report summarizes the results from testing conducted to evaluate the treatment of large volumes of water containing perfluorinated alkyl substances (PFAS). This summary of conclusions and observations about the performance and implementation of adsorptive treatment of AFFF contaminated water, based on the testing performed at the INL WSTB.

  16. Alkylating HIV-1 Nef - a potential way of HIV intervention

    Directory of Open Access Journals (Sweden)

    Cai Catherine

    2010-07-01

    Full Text Available Abstract Background Nef is a 27 KDa HIV-1 accessory protein. It downregulates CD4 from infected cell surface, a mechanism critical for efficient viral replication and pathogenicity. Agents that antagonize the Nef-mediated CD4 downregulation may offer a new class of drug to combat HIV infection and disease. TPCK (N-α-p-tosyl-L-phenylalanine chloromethyl ketone and TLCK (N-α-p-tosyl-L-lysine chloromethyl ketone are alkylation reagents that chemically modify the side chain of His or Cys residues in a protein. In search of chemicals that inhibit Nef function, we discovered that TPCK and TLCK alkylated HIV Nef. Methods Nef modification by TPCK was demonstrated on reducing SDS-PAGE. The specific cysteine residues modified were determined by site-directed mutagenesis and mass spectrometry (MS. The effect of TPCK modification on Nef-CD4 interaction was studied using fluorescence titration of a synthetic CD4 tail peptide with recombinant Nef-His protein. The conformational change of Nef-His protein upon TPCK-modification was monitored using CD spectrometry Results Incubation of Nef-transfected T cells, or recombinant Nef-His protein, with TPCK resulted in mobility shift of Nef on SDS-PAGE. Mutagenesis analysis indicated that the modification occurred at Cys55 and Cys206 in Nef. Mass spectrometry demonstrated that the modification was a covalent attachment (alkylation of TPCK at Cys55 and Cys206. Cys55 is next to the CD4 binding motif (A56W57L58 in Nef required for Nef-mediated CD4 downregulation and for AIDS development. This implies that the addition of a bulky TPCK molecule to Nef at Cys55 would impair Nef function and reduce HIV pathogenicity. As expected, Cys55 modification reduced the strength of the interaction between Nef-His and CD4 tail peptide by 50%. Conclusions Our data suggest that this Cys55-specific alkylation mechanism may be exploited to develop a new class of anti HIV drugs.

  17. Radioprotective action of 3-(imidazoline-2-alkyl)-5-methoxyindoles

    International Nuclear Information System (INIS)

    Bitny-Szlachto, S.; Kwiek, S.; Piotrowska, H.; Serafin, B.; Wejroch-Matacz, K.

    1977-01-01

    Radioprotective action in mice of four 3-(imidazoline-2'-alkyl)-5-methoxyindoles was examined and compared with that of 3-(2'-aminoethyl)-5-hydroxyindole (serotonine). The imidazoline-2-methyl derivatives (S 3 , S 4 ), applied in doses of 50 μmole/kg 10 min prior to irrdiation were found to reduce mortality of mice with LD 50 DRF of 1.14-1.15, while serotonine displayed DRF of 1.45. The imidazoline-2-ethyl derivatives (S 7 , S 8 ) have turned out to be ineffective. (author)

  18. Monolayer structures of alkyl aldehydes: Odd-membered homologues

    International Nuclear Information System (INIS)

    Phillips, T.K.; Clarke, S.M.; Bhinde, T.; Castro, M.A.; Millan, C.; Medina, S.

    2011-01-01

    Crystalline monolayers of three aldehydes with an odd number of carbon atoms in the alkyl chain (C 7 , C 9 and C 11 ) at low coverages are observed by a combination of X-ray and neutron diffraction. Analysis of the diffraction data is discussed and possible monolayer crystal structures are proposed; although unique structures could not be ascertained for all molecules. We conclude that the structures are flat on the surface, with the molecules lying in the plane of the layer. The C 11 homologue is determined to have a plane group of either p2, pgb or pgg, and for the C 7 homologue the p2 plane group is preferred.

  19. PARP inhibitors protect against sex- and AAG-dependent alkylation-induced neural degeneration.

    Science.gov (United States)

    Allocca, Mariacarmela; Corrigan, Joshua J; Fake, Kimberly R; Calvo, Jennifer A; Samson, Leona D

    2017-09-15

    Alkylating agents are commonly used to treat cancer. Although base excision repair (BER) is a major pathway for repairing DNA alkylation damage, under certain conditions, the initiation of BER produces toxic repair intermediates that damage healthy tissues. The initiation of BER by the alkyladenine DNA glycosylase (AAG, a.k.a. MPG) can mediate alkylation-induced cytotoxicity in specific cells in the retina and cerebellum of male mice. Cytotoxicity in both wild-type and Aag -transgenic ( AagTg ) mice is abrogated in the absence of Poly(ADP-ribose) polymerase-1 (PARP1). Here, we tested whether PARP inhibitors can also prevent alkylation-induced retinal and cerebellar degeneration in male and female WT and AagTg mice. Importantly, we found that WT mice display sex-dependent alkylation-induced retinal damage (but not cerebellar damage), with WT males being more sensitive than females. Accordingly, estradiol treatment protects males against alkylation-induced retinal degeneration. In AagTg male and female mice, the alkylation-induced tissue damage in both the retina and cerebellum is exacerbated and the sex difference in the retina is abolished. PARP inhibitors, much like Parp1 gene deletion, protect against alkylation-induced AAG-dependent neuronal degeneration in WT and AagTg mice, regardless of the gender, but their efficacy in preventing alkylation-induced neuronal degeneration depends on PARP inhibitor characteristics and doses. The recent surge in the use of PARP inhibitors in combination with cancer chemotherapeutic alkylating agents might represent a powerful tool for obtaining increased therapeutic efficacy while avoiding the collateral effects of alkylating agents in healthy tissues.

  20. Prenatal exposure to polycyclic aromatic hydrocarbons/aromatics, BDNF and child development.

    Science.gov (United States)

    Perera, Frederica; Phillips, David H; Wang, Ya; Roen, Emily; Herbstman, Julie; Rauh, Virginia; Wang, Shuang; Tang, Deliang

    2015-10-01

    Within a New York City (NYC) birth cohort, we assessed the associations between polycyclic aromatic hydrocarbon (PAH) and other aromatic DNA adducts and brain derived neurotrophic factor (BDNF) concentrations in umbilical cord blood, and neurodevelopment at age 2 years and whether BDNF is a mediator of the associations between PAH/aromatic-DNA adducts and neurodevelopment. PAH/aromatic-DNA adduct concentrations in cord blood were measured in 505 children born to nonsmoking African-American and Dominican women residing in NYC, and a subset was assessed for neurodevelopment at 2 years using the Bayley Scales of Infant Development Mental Development Index (MDI). A spectrum of PAH/aromatic-DNA adducts was measured using the (32)P-postlabeling assay; DNA adducts formed by benzo[a]pyrene (B[a]P), a representative PAH, were measured by High Performance Liquid Chromatography (HPLC)/fluorescence. BDNF mature protein in cord blood plasma was quantified by an ELISA. Multivariate regression analysis, adjusting for potential confounders, was conducted. PAH/aromatic-DNA adduct concentration measured by postlabeling was inversely associated with BDNF concentration (p=0.02) and with MDI scores at 2 years (p=0.04). BDNF level was positively associated with MDI scores (p=0.003). Restricting to subjects having all three measures (PAH/aromatic-DNA adducts by postlabeling, MDI, and BDNF), results were similar but attenuated (p=0.13, p=0.05, p=0.01, respectively). Associations between B[a]P-DNA adducts and BDNF and B[a]P-DNA adducts and MDI at age 2 years were not significant. At age 3 years, the positive association of BDNF with MDI was not observed. The results at age 2 suggest that prenatal exposure to a spectrum of PAH/aromatic pollutants may adversely affect early neurodevelopment, in part by reducing BDNF levels during the fetal period. However, the same relationship was not seen at age 3. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Push-pull vs captodative aromaticity.

    Science.gov (United States)

    Shainyan, Bagrat A; Fettke, Anja; Kleinpeter, Erich

    2008-10-30

    Vinylogs of fulvalenes with cyclopropenyl and cyclopentadienyl moieties attached either to different carbon atoms ( c-C 3H 2CHCHC 5H 4- c, 7) or to the same carbon atom [XC( c-C 3H 2)( c-C 5H 4), 10] [X = CH 2; C(CN) 2; C(NH 2) 2; C(OCH 2) 2; O; c-C 3H 2; c-C 5H 4; SiH 2; CCl 2] of the double bond inserted between the two rings are examined theoretically at the B3LYP/6-311G(d,p) level. Both types of compounds are shown to possess aromaticity, which was called "push-pull" and "captodative" aromaticity, respectively. For the captodative mesoionic structures XC( c-C 3H 2)( c-C 5H 4), the presence of both the two aromatic moieties and the CC double bond is the necessary and sufficient condition for their existence as energetic minima on the potential energy surface. Aromatic stabilization energy (ASE) was assessed by the use of homodesmotic reactions and heats of hydrogenation. Spatial magnetic criteria (through space NMR shieldings, TSNMRS) of the two types of vinylogous fulvalenes 7 and 10 have been calculated by the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept of Paul von Rague Schleyer, and visualized as iso-chemical-shielding surfaces (ICSS) of various sizes and directions. TSNMRS values can be successfully employed to visualize and quantify the partial push-pull and captodative aromaticity of both the three- and five-membered ring moieties. In addition, the push -pull effect in compounds 7 and 10 could be quantified by the occupation quotient pi* CC/pi CC of the double bond inserted between the two rings.

  2. Parsing of the free energy of aromatic-aromatic stacking interactions in solution

    Energy Technology Data Exchange (ETDEWEB)

    Kostjukov, Viktor V.; Khomytova, Nina M. [Department of Physics, Sevastopol National Technical University, Sevastopol 99053, Crimea (Ukraine); Hernandez Santiago, Adrian A.; Tavera, Anna-Maria Cervantes; Alvarado, Julieta Salas [Faculty of Chemical Sciences, Autonomous University of Puebla, Puebla (Mexico); Evstigneev, Maxim P., E-mail: max_evstigneev@mail.ru [Department of Physics, Sevastopol National Technical University, Sevastopol 99053, Crimea (Ukraine)

    2011-10-15

    Graphical abstract: Highlights: > A protocol for decomposition of the free energy of aromatic stacking is developed. > The factors stabilizing/destabilizing stacking of aromatic molecules are defined. > Hydrophobic contribution is found to be dominant. - Abstract: We report an analysis of the energetics of aromatic-aromatic stacking interactions for 39 non-covalent reactions of self- and hetero-association of 12 aromatic molecules with different structures and charge states. A protocol for computation of the contributions to the total energy from various energetic terms has been developed and the results are consistent with experiment in 92% of all the systems studied. It is found that the contributions from hydrogen bonds and entropic factors are always unfavorable, whereas contributions from van-der-Waals, electrostatic and/or hydrophobic effects may lead to stabilizing or destabilizing factors depending on the system studied. The analysis carried out in this work provides an answer to the questions 'What forces stabilize/destabilize the stacking of aromatic molecules in aqueous-salt solution and what are their relative importance?'

  3. Parsing of the free energy of aromatic-aromatic stacking interactions in solution

    International Nuclear Information System (INIS)

    Kostjukov, Viktor V.; Khomytova, Nina M.; Hernandez Santiago, Adrian A.; Tavera, Anna-Maria Cervantes; Alvarado, Julieta Salas; Evstigneev, Maxim P.

    2011-01-01

    Graphical abstract: Highlights: → A protocol for decomposition of the free energy of aromatic stacking is developed. → The factors stabilizing/destabilizing stacking of aromatic molecules are defined. → Hydrophobic contribution is found to be dominant. - Abstract: We report an analysis of the energetics of aromatic-aromatic stacking interactions for 39 non-covalent reactions of self- and hetero-association of 12 aromatic molecules with different structures and charge states. A protocol for computation of the contributions to the total energy from various energetic terms has been developed and the results are consistent with experiment in 92% of all the systems studied. It is found that the contributions from hydrogen bonds and entropic factors are always unfavorable, whereas contributions from van-der-Waals, electrostatic and/or hydrophobic effects may lead to stabilizing or destabilizing factors depending on the system studied. The analysis carried out in this work provides an answer to the questions 'What forces stabilize/destabilize the stacking of aromatic molecules in aqueous-salt solution and what are their relative importance?'

  4. Alkane and polycyclic aromatic hydrocarbons in sediments and benthic invertebrates of the northern Chukchi Sea

    Science.gov (United States)

    Harvey, H. Rodger; Taylor, Karen A.

    2017-10-01

    The Hanna Shoal region represents an important northern gateway for transport and deposition in the Chukchi Sea. This study determined the concentration and distribution of organic contaminants (aliphatic hydrocarbon and polycyclic aromatic hydrocarbons, PAHs) in surface sediments from 34 sites across Hanna Shoal. Up to 31 total PAHs, including parent and alkyl homologues were detected with total concentrations ranging from a low of 168 ng g-1 the western flank of Hanna Shoal (station H34) to 1147 ng g-1 at station in Barrow Canyon (station BarC5). Alkyl PAHs were more abundant than parent structures and accounted for 53-64% of the summed concentrations suggesting overall at background levels (< 1600 ng g-1) in sediments. Alkane (C15-C33) hydrocarbons ranged from 4.3 μg g-1 on the southern flank of Hanna shoal to 31 μg g-1 at a northern station. Sediments were often dominated by short chain (C15-C22) alkanes with overall terrestrial aquatic ratios (TAR) for the region averaging 0.20. Based on the ratio of Fl/(Fl+ Py) and BaF/(Baf+BeP) verses (BA/BA+Ch) in sediments, PAHs are largely derived from petrogenic sources with minor amounts of mixed combustion sources. A diversity of PAHs were detected in the northern whelk Neptunea heros foot muscle with total concentrations ranging from 0.14 to 1.5 μg g-1 dry tissue wt. Larger (and presumably older) animals showed higher levels of PAH per unit muscle tissue, suggesting that animals may bioaccumulate PAHs over time, with low but increasing concentrations also present in internal and external eggs. Alkane hydrocarbons were also higher in whelks with distributions similar to that seen in sediments. The mussel Muscularus discors collected in Barrow Canyon showed constrained distributions and substantially lower concentrations of both PAHs and alkanes than the surrounding surface sediments.

  5. Photochemical Formation of C1-C5 Alkyl Nitrates in Suburban Hong Kong and over the South China Sea.

    Science.gov (United States)

    Zeng, Lewei; Lyu, Xiaopu; Guo, Hai; Zou, Shichun; Ling, Zhenhao

    2018-04-24

    Alkyl nitrates (RONO 2 ) are important reservoirs of atmospheric nitrogen, regulating nitrogen cycling and ozone (O 3 ) formation. In this study, we found that propane and n-butane were significantly lower at the offshore site (WSI) in Hong Kong ( p 0.05). Stronger oxidative capacity at WSI led to more efficient RONO 2 formation. Relative incremental reactivity (RIR) was for the first time used to evaluate RONO 2 -precursor relationships. In contrast to a consistently volatile organic compounds (VOC)-limited regime at TC, RONO 2 formation at WSI switched from VOC-limited regime during O 3 episodes to VOC and nitrogen oxides (NO x ) colimited regime during nonepisodes. Furthermore, unlike the predominant contributions of parent hydrocarbons to C 4 -C 5 RONO 2 , the production of C 1 -C 3 RONO 2 was more sensitive to other VOCs like aromatics and carbonyls, which accounted for ∼40-90% of the productions of C 1 -C 3 alkylperoxy (RO 2 ) and alkoxy radicals (RO) at both sites. This resulted from the decomposition of larger RO 2 /RO and the change of OH abundance under the photochemistry of other VOCs. This study advanced our understanding of the photochemical formation of RONO 2 , particularly the relationships between RONO 2 and their precursors, which were not confined to the parent hydrocarbons.

  6. Gas-phase alkyl amines in urban air; comparison with a boreal forest site and importance for local atmospheric chemistry

    Science.gov (United States)

    Hellén, H.; Kieloaho, A.-J.; Hakola, H.

    2014-09-01

    Low-molecular-weight aliphatic amines were measured in the ambient urban background air at the SMEAR III station (Station for Measuring Forest Ecosystem-Atmosphere Relations III) in Helsinki, Finland, from May until late August 2011. The alkyl amines measured were dimethylamine (DMA), ethylamine (EA), trimethylamine (TMA), propylamine (PA), diethylamine (DEA), butylamine (BA) and triethylamine (TEA). Of these amines, DMA + EA and TMA + PA were the most abundant, with average concentrations of 24 and 8 ppt. The ranges of weekly mean concentrations of DMA + EA and TMA + PA were concentrations of all amines in urban background air in Helsinki were lower than at a boreal forest site (SMEAR II), indicating the presence at the latter site of some additional sources. Amine lifetimes are short, varying from 2.3 h to 7.6 h against hydroxyl (OH) radicals. The amine concentrations were scaled against OH reactivity and compared with the OH reactivities of aromatic hydrocarbons and terpenes. The results showed that amines strongly influenced the total OH reactivity, especially at the boreal forest site in May, September and October, showing contributions almost as high as those of monoterpenes.

  7. Selectivity of alkyl radical formation from branched alkanes studied by electron spin resonance and electron spin echo spectroscopy

    International Nuclear Information System (INIS)

    Tsuneki, Ichikawa; Hiroshi, Yoshida

    1992-01-01

    Alkyl radicals generated from branched alkanes by γ radiation are being measuring by electron spin resonance and electron spin echo spectroscopy. This research is being conducted to determine the mechanism of selective alkyl radical formation in low-temperature solids

  8. Paraffin Alkylation Using Zeolite Catalysts in a slurry reactor: Chemical Engineering Principles to Extend Catalyst Lifetime

    NARCIS (Netherlands)

    Jong, K.P. de; Mesters, C.M.A.M.; Peferoen, D.G.R.; Brugge, P.T.M. van; Groot, C. de

    1996-01-01

    The alkylation of isobutane with 2-butene is carried out using a zeolitic catalyst in a well stirred slurry reactor. Whereas application of fixed bed technology using a solid acid alkylation catalyst has in the led to catalysts lifetimes in the range of minutes, in this work we report catalyst

  9. REVISITING CLASSICAL NUCLEOPHILIC SUBSTITUTIONS IN AQUEOUS MEDIUM: MICROWAVE-ASSISTED SYNTHESIS OF ALKYL AZIDES

    Science.gov (United States)

    An efficient and clean synthesis of alkyl azides using microwave (MW) radiation is described in aqueous medium by reacting alkyl halides or tosylates with alkali azides. This general and expeditious MW-enhanced approach to nucleophilic substitution reactions is applicable to the ...

  10. Sources and proxy potential of long chain alkyl diols in lacustrine environments.

    NARCIS (Netherlands)

    Rampen, Sebastiaan W.; Datema, Mariska; Rodrigo-Gámiz, M.; Schouten, Stefan; Reichart, Gert-Jan; Sinninghe Damste, Jaap S.

    2014-01-01

    Long chain 1,13- and 1,15-alkyl diols form the base of a number of recently proposed proxies used for climate reconstruction. However, the sources of these lipids and environmental controls on their distribution are still poorly constrained. We have analyzed the long chain alkyl diol (LCD)

  11. Sources and proxy potential of long chain alkyl diols in lacustrine environments

    NARCIS (Netherlands)

    Rampen, S.; Datema, M.; Rodrigo-Gámiz, M.; Schouten, S.; Reichart, G.-J.; Sinninghe Damsté, J.S.

    2014-01-01

    Long chain 1,13- and 1,15-alkyl diols form the base of a number of recently proposed proxies used for climate reconstruction. However, the sources of these lipids and environmental controls on their distribution are still poorly constrained. We have analyzed the long chain alkyl diol (LCD)

  12. 40 CFR 721.5860 - Methylphenol, bis(sub-sti-tuted)alkyl.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Methylphenol, bis(sub-sti-tuted)alkyl... Substances § 721.5860 Methylphenol, bis(sub-sti-tuted)alkyl. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as methylphenol, bis-(sub-sti-tut...

  13. Synthesis of 2-substituted tryptophans via a C3- to C2-alkyl migration

    Directory of Open Access Journals (Sweden)

    Michele Mari

    2014-08-01

    Full Text Available The reaction of 3-substituted indoles with dehydroalanine (Dha derivatives under Lewis acid-mediated conditions has been investigated. The formation of 2-substituted tryptophans is proposed to occur through a selective alkylative dearomatization–cyclization followed by C3- to C2-alkyl migration and rearomatization.

  14. Selective alkylation of T–T mismatched DNA using vinyldiaminotriazine–acridine conjugate

    Science.gov (United States)

    Onizuka, Kazumitsu; Usami, Akira; Yamaoki, Yudai; Kobayashi, Tomohito; Hazemi, Madoka E; Chikuni, Tomoko; Sato, Norihiro; Sasaki, Kaname; Katahira, Masato

    2018-01-01

    Abstract The alkylation of the specific higher-order nucleic acid structures is of great significance in order to control its function and gene expression. In this report, we have described the T–T mismatch selective alkylation with a vinyldiaminotriazine (VDAT)–acridine conjugate. The alkylation selectively proceeded at the N3 position of thymidine on the T–T mismatch. Interestingly, the alkylated thymidine induced base flipping of the complementary base in the duplex. In a model experiment for the alkylation of the CTG repeats DNA which causes myotonic dystrophy type 1 (DM1), the observed reaction rate for one alkylation increased in proportion to the number of T–T mismatches. In addition, we showed that primer extension reactions with DNA polymerase and transcription with RNA polymerase were stopped by the alkylation. The alkylation of the repeat DNA will efficiently work for the inhibition of replication and transcription reactions. These functions of the VDAT–acridine conjugate would be useful as a new biochemical tool for the study of CTG repeats and may provide a new strategy for the molecular therapy of DM1. PMID:29309639

  15. Selective alkylation of T-T mismatched DNA using vinyldiaminotriazine-acridine conjugate.

    Science.gov (United States)

    Onizuka, Kazumitsu; Usami, Akira; Yamaoki, Yudai; Kobayashi, Tomohito; Hazemi, Madoka E; Chikuni, Tomoko; Sato, Norihiro; Sasaki, Kaname; Katahira, Masato; Nagatsugi, Fumi

    2018-02-16

    The alkylation of the specific higher-order nucleic acid structures is of great significance in order to control its function and gene expression. In this report, we have described the T-T mismatch selective alkylation with a vinyldiaminotriazine (VDAT)-acridine conjugate. The alkylation selectively proceeded at the N3 position of thymidine on the T-T mismatch. Interestingly, the alkylated thymidine induced base flipping of the complementary base in the duplex. In a model experiment for the alkylation of the CTG repeats DNA which causes myotonic dystrophy type 1 (DM1), the observed reaction rate for one alkylation increased in proportion to the number of T-T mismatches. In addition, we showed that primer extension reactions with DNA polymerase and transcription with RNA polymerase were stopped by the alkylation. The alkylation of the repeat DNA will efficiently work for the inhibition of replication and transcription reactions. These functions of the VDAT-acridine conjugate would be useful as a new biochemical tool for the study of CTG repeats and may provide a new strategy for the molecular therapy of DM1.

  16. Detection and identification of alkylating agents by using a bioinspired "chemical nose".

    Science.gov (United States)

    Hertzog-Ronen, Carmit; Borzin, Elena; Gerchikov, Yulia; Tessler, Nir; Eichen, Yoav

    2009-10-12

    Alkylating agents are simple and reactive molecules that are commonly used in many and diverse fields such as organic synthesis, medicine, and agriculture. Some highly reactive alkylating species are also being used as blister chemical-warfare agents. The detection and identification of alkylating agents is not a trivial issue because of their high reactivity and simple structure. Herein, we report on a new multispot luminescence-based approach to the detection and identification of alkylating agents. In order to demonstrate the potential of the approach, seven pi-conjugated oligomers and polymers bearing nucleophilic pyridine groups, 1-7, were adsorbed onto a solid support and exposed to vapors of alkylators 8-15. The alkylation-induced color-shift patterns of the seven-spot array allow clear discrimination of the different alkylators. The spots are sensitive to minute concentrations of alkylators and, because the detection is based on the formation of new covalent bonds, these spots saturate at about 50 ppb.

  17. Synthesis of alkylated deoxyno irimycin and 1,5-dideoxy-1,5-iminoxylitol analogues:

    DEFF Research Database (Denmark)

    Szczepina, M.G.; Johnston, B.D; Yuan, Y.

    2004-01-01

    The syntheses of N-alkylated deoxynojirimycin and 1,5-dideoxy-1,5-iminoxylitol derivatives having either a D- or an L-erythritol-3-sulfate functionalized N-substituent are reported. The alkylating agent used was a cyclic sulfate derivative, whereby selective attack of the nitrogen atom at the least...

  18. Alkylation damage causes MMR-dependent chromosomal instability in vertebrate embryos.

    NARCIS (Netherlands)

    Feitsma, H.; Akay, A.; Cuppen, E.

    2008-01-01

    S(N)1-type alkylating agents, like N-methyl-N-nitrosourea (MNU) and N-ethyl-N-nitrosourea (ENU), are potent mutagens. Exposure to alkylating agents gives rise to O(6)-alkylguanine, a modified base that is recognized by DNA mismatch repair (MMR) proteins but is not repairable, resulting in

  19. Chemistry of the pyrazolidines. 26. Alkylation of 4-benzyliden-1-phenyl-3,5-dioxopyrazolidines

    International Nuclear Information System (INIS)

    Moldarev, B.L.; Aronzon, M.E.; Adanin, V.M.; Zyakun, A.M.

    1986-01-01

    The reaction of 4-benzyliden-1-phenyl-3,5-dioxopyrazolidines with alkyl halides in the presence of sodium alkoxide gave 1-phenyl-2-alkyl-4-benzyliden- and 1-phenyl-2,4-dialkyl-4-(α-alkoxybenzyl)-3,4-dioxopyrazolines. The structures of these compounds were confirmed by UV, IR, and PMR spectroscopy, and by mass-spectrometry

  20. RELATION BETWEEN SURFACTANT STRUCTURE AND PROPERTIES OF SPHERICAL MICELLES - 1-ALKYL-4-ALKYLPYRIDINIUM HALIDE SURFACTANTS

    NARCIS (Netherlands)

    NUSSELDER, JJH; ENGBERTS, JBFN

    1991-01-01

    This paper describes a detailed study of the properties of spherical micelles formed from 18 1-alkyl-4-alkylpyridinium iodides. Structural variations in the surfactants include (i) branching of the 4-alkyl chain while keeping the number of carbons in the chain invariant and (ii) variation of the

  1. Rh(III-Catalyzed, Highly Selectively Direct C–H Alkylation of Indoles with Diazo Compounds

    Directory of Open Access Journals (Sweden)

    Kang Wan

    2016-06-01

    Full Text Available Rh(III-catalyzed regioselective alkylation of indoles with diazo compounds as a highly efficient and atom-economic protocol for the synthesis of alkyl substituted indoles has been developed. The reaction could proceed under mild conditions and afford a series of desired products in good to excellent yields.

  2. Industrial tests of a new technology for sulfuric acid alkylation of isobutane by olefines

    Energy Technology Data Exchange (ETDEWEB)

    Tarakanov, V.S.; Karamyshev, M.S.; Khadzhiyev, S.N.; Mel' man, A.Z.

    1971-01-01

    A complex of elements of a new technology for sulfuric acid alkylation of isobutane by alkenes with the use of a KSG-2 reactor and an acetic settler of a new design is realized as a result of the joint work of the Novo-Yaroslav oil refinery, GrozNII, VNIIOINeft and VNIINeftemash in an alkylation installation.

  3. Mechanism of alkylation of isobutane by olefins in the presence of sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Baiburskii, V.L.; Khadzhiev, S.N.; Ovsyannikov, V.P.

    1992-05-10

    The authors attempted here to examine the mechanism of alkylation of isobutane by olefins in the presence of sulfuric acid in terms of an initial stage of activation of isoparaffin. The version of formation of tert-alkyl cations and the role of the catalyst in this stage were analyzed. 10 refs., 1 fig., 1 tab.

  4. Differential alkylation-based redox proteomics – Lessons learnt

    Science.gov (United States)

    Wojdyla, Katarzyna; Rogowska-Wrzesinska, Adelina

    2015-01-01

    Cysteine is one of the most reactive amino acids. This is due to the electronegativity of sulphur atom in the side chain of thiolate group. It results in cysteine being present in several distinct redox forms inside the cell. Amongst these, reversible oxidations, S-nitrosylation and S-sulfenylation are crucial mediators of intracellular redox signalling, with known associations to health and disease. Study of their functionalities has intensified thanks to the development of various analytical strategies, with particular contribution from differential alkylation-based proteomics methods. Presented here is a critical evaluation of differential alkylation-based strategies for the analysis of S-nitrosylation and S-sulfenylation. The aim is to assess the current status and to provide insights for future directions in the dynamically evolving field of redox proteomics. To achieve that we collected 35 original research articles published since 2010 and analysed them considering the following parameters, (i) resolution of modification site, (ii) quantitative information, including correction of modification levels by protein abundance changes and determination of modification site occupancy, (iii) throughput, including the amount of starting material required for analysis. The results of this meta-analysis are the core of this review, complemented by issues related to biological models and sample preparation in redox proteomics, including conditions for free thiol blocking and labelling of target cysteine oxoforms. PMID:26282677

  5. Differential alkylation-based redox proteomics--Lessons learnt.

    Science.gov (United States)

    Wojdyla, Katarzyna; Rogowska-Wrzesinska, Adelina

    2015-12-01

    Cysteine is one of the most reactive amino acids. This is due to the electronegativity of sulphur atom in the side chain of thiolate group. It results in cysteine being present in several distinct redox forms inside the cell. Amongst these, reversible oxidations, S-nitrosylation and S-sulfenylation are crucial mediators of intracellular redox signalling, with known associations to health and disease. Study of their functionalities has intensified thanks to the development of various analytical strategies, with particular contribution from differential alkylation-based proteomics methods. Presented here is a critical evaluation of differential alkylation-based strategies for the analysis of S-nitrosylation and S-sulfenylation. The aim is to assess the current status and to provide insights for future directions in the dynamically evolving field of redox proteomics. To achieve that we collected 35 original research articles published since 2010 and analysed them considering the following parameters, (i) resolution of modification site, (ii) quantitative information, including correction of modification levels by protein abundance changes and determination of modification site occupancy, (iii) throughput, including the amount of starting material required for analysis. The results of this meta-analysis are the core of this review, complemented by issues related to biological models and sample preparation in redox proteomics, including conditions for free thiol blocking and labelling of target cysteine oxoforms. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  6. The isobutylene-isobutane alkylation process in liquid HF revisited.

    Science.gov (United States)

    Esteves, P M; Araújo, C L; Horta, B A C; Alvarez, L J; Zicovich-Wilson, C M; Ramírez-Solís, A

    2005-07-07

    Details on the mechanism of HF catalyzed isobutylene-isobutane alkylation were investigated. On the basis of available experimental data and high-level quantum chemical calculations, a detailed reaction mechanism is proposed taking into account solvation effects of the medium. On the basis of our computational results, we explain why the density of the liquid media and stirring rates are the most important parameters to achieve maximum yield of alkylate, in agreement with experimental findings. The ab initio Car-Parrinello molecular dynamics calculations show that isobutylene is irreversibly protonated in the liquid HF medium at higher densities, leading to the ion pair formation, which is shown to be a minimum on the potential energy surface after optimization using periodic boundary conditions. The HF medium solvates preferentially the fluoride anion, which is found as solvated [FHF](-) or solvated F(-.)(HF)(3). On the other hand, the tert-butyl cation is weakly solvated, where the closest HF molecules appear at a distance of about 2.9 Angstrom with the fluorine termination of an HF chain.

  7. Synthesis and Biological Evaluation of N-Alkyl-3-(alkylamino-pyrazine-2-carboxamides

    Directory of Open Access Journals (Sweden)

    Lucia Semelkova

    2015-05-01

    Full Text Available A series of N-alkyl-3-(alkylaminopyrazine-2-carboxamides and their N-alkyl-3-chloropyrazine-2-carboxamide precursors were prepared. All compounds were characterized by analytical methods and tested for antimicrobial and antiviral activity. The antimycobacterial MIC values against Mycobacterium tuberculosis H37Rv of the most effective compounds, 3-(hexylamino-, 3-(heptylamino- and 3-(octylamino-N-methyl-pyrazine-2-carboxamides 14‒16, was 25 μg/mL. The compounds inhibited photosystem 2 photosynthetic electron transport (PET in spinach chloroplasts. This activity was strongly connected with the lipophilicity of the compounds. For effective PET inhibition longer alkyl chains in the 3-(alkylamino substituent in the N-alkyl-3-(alkylaminopyrazine-2-carboxamide molecule were more favourable than two shorter alkyl chains.

  8. Building blocks for ionic liquids: Vapor pressures and vaporization enthalpies of 1-(n-alkyl)-imidazoles

    International Nuclear Information System (INIS)

    Emel'yanenko, Vladimir N.; Portnova, Svetlana V.; Verevkin, Sergey P.; Skrzypczak, Andrzej; Schubert, Thomas

    2011-01-01

    Highlights: → We measured vapor pressures of the 1-(n-alkyl)-imidazoles by transpiration method. → Variations on the alkyl chain length n were C 3 , C 5 -C 7 , and C 9 -C 10 . → Enthalpies of vaporization were derived from (p, T) dependencies. → Enthalpies of vaporization at 298.15 K were linear dependent on the chain length. - Abstract: Vapor pressures of the linear 1-(n-alkyl)-imidazoles with the alkyl chain C 3 , C 5 -C 7 , and C 9 -C 10 have been measured by the transpiration method. The molar enthalpies of vaporization Δ l g H m of these compounds were derived from the temperature dependencies of vapor pressures. A linear correlation of enthalpies of vaporization Δ l g H m (298.15 K) of the 1-(n-alkyl)-imidazoles with the chain length has been found.

  9. Thermochemical investigation into coordination ability of zinc and cadmium alkyl compounds in solutions

    International Nuclear Information System (INIS)

    Aleksandrov, Yu.A.; Fedostseva, G.A.; Tsvetkov, V.G.; Lebedev, S.A.; Kozyrkin, B.I.

    1983-01-01

    Enthalpies of zinc alkyl compounds mixing, as well as those of dimethyl cadmium mixing with hexane, previously used as a solvent during the study of liquid-phase autooxidation of Me 2 Cd and Me 2 Zn, and with a series of organic bases at 298 K and at components ratio 1:1 or 1:2, are determined. Using calorimetric method dimethyl cadmium association in liquid state has been evaluated. Coordination ability of zinc alkyl compounds is higher than for the corresponding cadmium compounds. With the increase of alkyl radical length the electron seeking ability of zinc compounds decreases. On the basis of thermochemical data relative stability of coordination compounds of zinc and cadmium alkyl compounds with certain alkyl compounds of group 6 elements is evaluated: it has the maximum value for sulfur compounds

  10. The Impact of Commonly Used Alkylating Agents on Artifactual Peptide Modification.

    Science.gov (United States)

    Hains, Peter G; Robinson, Phillip J

    2017-09-01

    Iodoacetamide is by far the most commonly used agent for alkylation of cysteine during sample preparation for proteomics. An alternative, 2-chloroacetamide, has recently been suggested to reduce the alkylation of residues other than cysteine, such as the N-terminus, Asp, Glu, Lys, Ser, Thr, and Tyr. Here we show that although 2-chloroacetamide reduces the level of off-target alkylation, it exhibits a range of adverse effects. The most significant of these is methionine oxidation, which increases to a maximum of 40% of all Met-containing peptides, compared with 2-5% with iodoacetamide. Increases were also observed for mono- and dioxidized tryptophan. No additional differences between the alkylating reagents were observed for a range of other post-translational modifications and digestion parameters. The deleterious effects were observed for 2-chloroacetamide from three separate suppliers. The adverse impact of 2-chloroacetamide on methionine oxidation suggests that it is not the ideal alkylating reagent for proteomics.

  11. Alkylation damage in DNA and RNA--repair mechanisms and medical significance

    DEFF Research Database (Denmark)

    Drabløs, Finn; Feyzi, Emadoldin; Aas, Per Arne

    2004-01-01

    Alkylation lesions in DNA and RNA result from endogenous compounds, environmental agents and alkylating drugs. Simple methylating agents, e.g. methylnitrosourea, tobacco-specific nitrosamines and drugs like temozolomide or streptozotocin, form adducts at N- and O-atoms in DNA bases. These lesions......, inactivation of the MMR system in an AGT-defective background causes resistance to the killing effects of O(6)-alkylating agents, but not to the mutagenic effect. Bifunctional alkylating agents, such as chlorambucil or carmustine (BCNU), are commonly used anti-cancer drugs. DNA lesions caused by these agents...... are mainly repaired by direct base repair, base excision repair, and to some extent by nucleotide excision repair (NER). The identified carcinogenicity of O(6)-methylguanine (O(6)-meG) is largely caused by its miscoding properties. Mutations from this lesion are prevented by O(6)-alkylG-DNA alkyltransferase...

  12. Aromatic Structure in Simulates Titan Aerosol

    Science.gov (United States)

    Trainer, Melissa G.; Loeffler, M. J.; Anderson, C. M.; Hudson, R. L.; Samuelson, R. E.; Moore, M. A.

    2011-01-01

    Observations of Titan by the Cassini Composite Infrared Spectrometer (CIRS) between 560 and 20 per centimeter (approximately 18 to 500 micrometers) have been used to infer the vertical variations of Titan's ice abundances, as well as those of the aerosol from the surface to an altitude of 300 km [1]. The aerosol has a broad emission feature centered approximately at 140 per centimeter (71 micrometers). As seen in Figure 1, this feature cannot be reproduced using currently available optical constants from laboratory-generated Titan aerosol analogs [2]. The far-IR is uniquely qualified for investigating low-energy vibrational motions within the lattice structures of COITIDlex aerosol. The feature observed by CIRS is broad, and does not likely arise from individual molecules, but rather is representative of the skeletal movements of macromolecules. Since Cassini's arrival at Titan, benzene (C6H6) has been detected in the atmosphere at ppm levels as well as ions that may be polycyclic aromatic hydrocarbons (PAHs) [3]. We speculate that the feature may be a blended composite that can be identified with low-energy vibrations of two-dimensional lattice structures of large molecules, such as PAHs or nitrogenated aromatics. Such structures do not dominate the composition of analog materials generated from CH4 and N2 irradiation. We are performing studies forming aerosol analog via UV irradiation of aromatic precursors - specifically C6H6 - to understand how the unique chemical architecture of the products will influence the observable aerosol characteristics. The optical and chemical properties of the aromatic analog will be compared to those formed from CH4/N2 mixtures, with a focus on the as-yet unidentified far-IR absorbance feature. Preliminary results indicate that the photochemically-formed aromatic aerosol has distinct chemical composition, and may incorporate nitrogen either into the ring structure or adjoined chemical groups. These compositional differences are

  13. Glutamine deficiency induces DNA alkylation damage and sensitizes cancer cells to alkylating agents through inhibition of ALKBH enzymes.

    Directory of Open Access Journals (Sweden)

    Thai Q Tran

    2017-11-01

    Full Text Available Driven by oncogenic signaling, glutamine addiction exhibited by cancer cells often leads to severe glutamine depletion in solid tumors. Despite this nutritional environment that tumor cells often experience, the effect of glutamine deficiency on cellular responses to DNA damage and chemotherapeutic treatment remains unclear. Here, we show that glutamine deficiency, through the reduction of alpha-ketoglutarate, inhibits the AlkB homolog (ALKBH enzymes activity and induces DNA alkylation damage. As a result, glutamine deprivation or glutaminase inhibitor treatment triggers DNA damage accumulation independent of cell death. In addition, low glutamine-induced DNA damage is abolished in ALKBH deficient cells. Importantly, we show that glutaminase inhibitors, 6-Diazo-5-oxo-L-norleucine (DON or CB-839, hypersensitize cancer cells to alkylating agents both in vitro and in vivo. Together, the crosstalk between glutamine metabolism and the DNA repair pathway identified in this study highlights a potential role of metabolic stress in genomic instability and therapeutic response in cancer.

  14. Antimicrobial and diffusional correlation of N-alkyl betaines and N-alkyl-N,N-dimethylamine oxides from semisolids.

    Science.gov (United States)

    Birnie, C R; Malamud, D; Thomulka, K W; Schwartz, J B; Schnaare, R L

    2001-09-01

    Previous studies have shown that two classes of amphoteric surfactants, N-alkyl betaines and N-alkyl-N,N-dimethylamine oxides, exhibit pronounced antimicrobial activity in combination and have potential for use in a semisolid formulation for topical or vaginal delivery. In this work, several potential delivery systems were prepared and evaluated for antimicrobial activity and diffusional properties. A novel antimicrobial test for semisolids was proposed that determined the contact time needed to kill microorganisms. The unformulated agents in solution exhibited the faster kill within 60 min, followed by the hydroxyethylcellulose gel formulation in 90 min, and the poloxamer gel and a cream that required several hours. Diffusion from the dosage form utilized a Slide-A-Lyzer diffusion cassette with a 10,000 MWCO membrane with (14)C-labeled active species added to the aforementioned antimicrobial formulations. Diffusion of the individual betaine and amine oxide derivatives were tracked over time to determine the diffusion rates and profiles of the components in each formulation and in solution. The betaine derivative diffused up to three times faster than the amine oxide derivative within the first 2 h, but the amount diffused was approximately equivalent at 24 h. The formulations delayed release in the same rank order as the contact time kill analysis: hydroxyethylcellulose gel > poloxamer gel > cream. Copyright 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association

  15. Silicone elastomers with aromatic voltage stabilizers

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Skov, Anne Ladegaard

    A method to synthesise a polydimethylsiloxane-polyphenylmethylsiloxane (PDMS-PPMS) copolymer with electron-trapping effects has been developed utilising a quickhydrosilylation reaction at ambient temperature and crosslinking via hydrosilylation by a vinyl-functional crosslinker. The mechanism...... of electron-trapping by aromatic compounds grafted to silicone backbones in a crosslinked PDMS is illustrated in Fig. 1. The electrical breakdown strength, the storage modulus and the loss modulus of the elastomer were investigated, as well as the excitation energy from the collision between electron carriers...... and benzene rings in PDMS-PPMS copolymer was measured by UV-vis spectroscopy. The developed elastomers were inherently soft with enhanced electrical breakdown strength due to delocalized pi-electrons of aromatic rings attached to the silicone backbone. The dielectric relative permittivity of PDMS...

  16. Detecting the building blocks of aromatics

    Science.gov (United States)

    Joblin, Christine; Cernicharo, José

    2018-01-01

    Interstellar clouds are sites of active organic chemistry (1). Many small, gasphase molecules are found in the dark parts of the clouds that are protected from ultraviolet (UV) photons, but these molecules photodissociate in the external layers of the cloud that are exposed to stellar radiation (see the photo). These irradiated regions are populated by large polycyclic aromatic hydrocarbons (PAHs) with characteristic infrared (IR) emission features. These large aromatics are expected to form from benzene (C6H6), which is, however, difficult to detect because it does not have a permanent dipole moment and can only be detected via its IR absorption transitions against a strong background source (2). On page 202 of this issue, McGuire et al. (3) report the detection of benzonitrile (c-C6H5CN) with radio telescopes. Benzonitrile likely forms in the reaction of CN with benzene; from its observation, it is therefore possible to estimate the abundance of benzene itself.

  17. Hydrocarbon fractions. Aromatic determination by mass spectrometry

    International Nuclear Information System (INIS)

    Anon.

    Analysis of hydrocarbon fractions by mass spectrometry using low energy electrons, for determination of aromatic hydrocarbons repartition, suitable for fraction with the following properties: boiling point up to 320 0 C, whithout olefine, sulfur content up to 0.1 per cent, boiling range up to 100 0 C, if the final temperature is 200 0 C, and up to 50 0 C, if over 200 0 C [fr

  18. Aromatic compounds from three Brazilian Lauraceae species

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Andrea Nastri de Luca; Batista Junior, Joao Marcos; Lopez, Silvia Noeli; Furlan, Maysa; Cavalheiro, Alberto Jose; Silva, Dulce Helena Siqueira; Bolzani, Vanderlan da Silva [UNESP, Araraquara, SP (Brazil). Inst. de Quimica. Dept. de Quimica Organica; Nunomura, Sergio Massayoshi [Instituto Nacional de Pesquisa da Amazonia (INPA), Manaus, AM (Brazil). Dept. de Produtos Naturais; Yoshida, Massayoshi [Centro de Biotecnologia da Amazonia, Manaus, AM (Brazil)

    2010-07-01

    Phytochemical investigations on three Brazilian Lauraceae species from the Cerrado region of Sao Paulo State, Ocotea corymbosa (Meins) Mez., O. elegans Mez. and Persea pyrifolia Nees and Mart. ex Nees resulted in the isolation of flavonoids, an ester of the 4-O-E-caffeoylquinic acid, an aromatic sesquiterpene besides furofuran lignans. This is the first chemical study on the leaves of Ocotea elegans and O. corymbosa as well as the first report of non-volatile compounds from Persea pyrifolia. (author)

  19. Aromatic compounds from three Brazilian Lauraceae species

    International Nuclear Information System (INIS)

    Batista, Andrea Nastri de Luca; Batista Junior, Joao Marcos; Lopez, Silvia Noeli; Furlan, Maysa; Cavalheiro, Alberto Jose; Silva, Dulce Helena Siqueira; Bolzani, Vanderlan da Silva

    2010-01-01

    Phytochemical investigations on three Brazilian Lauraceae species from the Cerrado region of Sao Paulo State, Ocotea corymbosa (Meins) Mez., O. elegans Mez. and Persea pyrifolia Nees and Mart. ex Nees resulted in the isolation of flavonoids, an ester of the 4-O-E-caffeoylquinic acid, an aromatic sesquiterpene besides furofuran lignans. This is the first chemical study on the leaves of Ocotea elegans and O. corymbosa as well as the first report of non-volatile compounds from Persea pyrifolia. (author)

  20. Aromatics Oxidation and Soot Formation in Flames

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J. B.; Richter, H.

    2005-03-29

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and the growth process to polycyclic aromatic hydrocarbons (PAH) of increasing size, soot and fullerenes formation in flames. The overall objective of the experimental aromatics oxidation work is to extend the set of available data by measuring concentration profiles for decomposition intermediates such as phenyl, cyclopentadienyl, phenoxy or indenyl radicals which could not be measured with molecular-beam mass spectrometry to permit further refinement and testing of benzene oxidation mechanisms. The focus includes PAH radicals which are thought to play a major role in the soot formation process while their concentrations are in many cases too low to permit measurement with conventional mass spectrometry. The radical species measurements are used in critical testing and improvement of a kinetic model describing benzene oxidation and PAH growth. Thermodynamic property data of selected species are determined computationally, for instance using density functional theory (DFT). Potential energy surfaces are explored in order to identify additional reaction pathways. The ultimate goal is to understand the conversion of high molecular weight compounds to nascent soot particles, to assess the roles of planar and curved PAH and relationships between soot and fullerenes formation. The specific aims are to characterize both the high molecular weight compounds involved in the nucleation of soot particles and the structure of soot including internal nanoscale features indicative of contributions of planar and/or curved PAH to particle inception.

  1. The unique aromatic catabolic genes in sphingomonads degrading polycyclic aromatic hydrocarbons (PAHs).

    Science.gov (United States)

    Pinyakong, Onruthai; Habe, Hiroshi; Omori, Toshio

    2003-02-01

    Many members of the sphingomonad genus isolated from different geological areas can degrade a wide variety of polycyclic aromatic hydrocarbons (PAHs) and related compounds. These sphingomonads such as Sphingobium yanoikuyae strain B1, Novosphingobium aromaticivorans strain F199, and Sphingobium sp. strain P2 have been found to possess a unique group of genes for aromatic degradation, which are distantly related with those in pseudomonads and other genera reported so far both in sequence homology and gene organization. Genes for aromatics degradation in these sphingomonads are complexly arranged; the genes necessary for one degradation pathway are scattered through several clusters. These aromatic catabolic gene clusters seem to be conserved among many other sphingomonads such as Sphingobium yanoikuyae strain Q1, Sphingomonas paucimobilis strain TNE12, S. paucimobilis strain EPA505, Sphingobium agrestis strain HV3, and Sphingomonas chungbukensis strain DJ77. Furthermore, some genes for naphthalenesulfonate degradation found in Sphingomonas xenophaga strain BN6 also share a high sequence homology with their homologues found in these sphingomonads. On the other hand, protocatechuic catabolic gene clusters found in fluorene-degrading Sphingomonas sp. strain LB126 appear to be more closely related with those previously found in lignin-degrading S. paucimobilis SYK-6 than the genes in this group of sphingomonads. This review summarizes the information on the distribution of these strains and relationships among their aromatic catabolic genes.

  2. Strong CH/O interactions between polycyclic aromatic hydrocarbons and water: Influence of aromatic system size.

    Science.gov (United States)

    Veljković, Dušan Ž

    2018-03-01

    Energies of CH/O interactions between water molecule and polycyclic aromatic hydrocarbons with a different number of aromatic rings were calculated using ab initio calculations at MP2/cc-PVTZ level. Results show that an additional aromatic ring in structure of polycyclic aromatic hydrocarbons significantly strengthens CH/O interactions. Calculated interaction energies in optimized structures of the most stable tetracene/water complex is -2.27 kcal/mol, anthracene/water is -2.13 kcal/mol and naphthalene/water is -1.97 kcal/mol. These interactions are stronger than CH/O contacts in benzene/water complex (-1.44 kcal/mol) while CH/O contacts in tetracene/water complex are even stronger than CH/O contacts in pyridine/water complexes (-2.21 kcal/mol). Electrostatic potential maps for different polycyclic aromatic hydrocarbons were calculated and used to explain trends in the energies of interactions. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Reactivity patterns of transition metal hydrides and alkyls

    International Nuclear Information System (INIS)

    Jones, W.D. II.

    1979-05-01

    The complex PPN + CpV(CO) 3 H - (Cp=eta 5 -C 5 H 5 and PPN = (Ph 3 P) 2 ) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN + CpV(CO) 3 H - reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN + [CpV(C) 3 X] - and in some cases the binuclear bridging hydride PPN + [CpV(CO) 3 ] 2 H - . The borohydride salt PPN + [CpV(CO) 3 BH 4 ] - has also been prepared. The reaction between CpV(CO) 3 H - and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO) 3 H - . Sodium amalgam reduction of CpRh(CO) 2 or a mixture of CpRh(CO) 2 and CpCo(CO) 2 affords two new anions, PPN + [Cp 2 Rh 3 (CO) 4 ] - and PPN + [Cp 2 RhCo(CO) 2 ] - . CpMo(CO) 3 H reacts with CpMo(CO) 3 R (R=CH 3 ,C 2 H 5 , CH 2 C 6 H 5 ) at 25 to 50 0 C to produce aldehyde RCHO and the dimers [CpMo(CO) 3 ] 2 and [CpMo(CO) 2 ] 2 . In general, CpV(CO) 3 H - appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO) 3 H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO) 3 H - generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO) 3 H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species

  4. Characterization of a topologically unique oxygenase from Sphingobium sp. PNB capable of catalyzing a broad spectrum of aromatics.

    Science.gov (United States)

    Khara, Pratick; Roy, Madhumita; Chakraborty, Joydeep; Dutta, Arindam; Dutta, Tapan K

    2018-04-01

    A Rieske non-heme iron ring-hydroxylating oxygenase (RHO) from Sphingobium sp. PNB involved in the initial oxidation of a wide range of low and high molecular weight polycyclic aromatic hydrocarbons (PAHs) was investigated. The RHO was shown to comprise of the gene products of distantly located ahdA1f-ahdA2f, ahdA3 and ahdA4 genes, which encoded the oxygenase α- and β-subunits, ferredoxin and reductase, respectively. In silico structural analysis of AhdA1f revealed a very large substrate-binding pocket, satisfying the spatial requirements to accommodate high molecular weight substrates. In addition, an atypical substrate access channel was noticed from the topology analysis of the oxygenase. Guided by molecular docking studies, dioxygenation of several PAHs as well as alkyl- and aryl benzenes was examined with the recombinant AhdA1fA2f expressed in Escherichia coli. Chromatographic and mass spectrometric analyses confirmed that AhdA1fA2f displays broad substrate specificity towards a wide range of aromatic hydrocarbons including potential xenobiotics, demonstrating metabolic robustness of strain PNB. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Breastfeeding as an Exposure Pathway for Perfluorinated Alkylates

    DEFF Research Database (Denmark)

    Mogensen, Ulla B; Grandjean, Philippe; Nielsen, Flemming

    2015-01-01

    Perfluorinated alkylate substances (PFASs) are widely used and have resulted in human exposures worldwide. PFASs occur in breast milk, and the duration of breastfeeding is associated with serum-PFAS concentrations in children. To determine the time-dependent impact of this exposure pathway, we...... examined the serum concentrations of five major PFASs in a Faroese birth cohort at birth, and at ages 11, 18, and 60 months. Information about the children's breastfeeding history was obtained from the mothers. The trajectory of serum-PFAS concentrations during months with and without breastfeeding...... was examined by linear mixed models that accounted for the correlations of the PFAS measurements for each child. The models were adjusted for confounders such as body size. The duration of exclusive breastfeeding was associated with increases of most PFAS concentrations by up to 30% per month, with lower...

  6. Synthesis and Antiangiogenic Activity of N-Alkylated Levamisole Derivatives

    DEFF Research Database (Denmark)

    Hansen, Anders N.; Bendiksen, Christine D.; Sylvest, Lene

    2012-01-01

    less effective than antibody treatment and are also associated with serious side effects. The discovery of new chemotypes with efficient antiangiogenic activity is therefore of pertinent interest. (S)-Levamisole hydrochloride, an anthelminthic drug approved for human use and with a known clinical...... profile, was recently shown to be an inhibitor of angiogenesis in vitro and exhibited tumor growth inhibition in mice. Here we describe the synthesis and in vitro evaluation of a series of N-alkylated analogues of levamisole with the aim of characterizing structure-activity relationships with regard...... to inhibition of angiogenesis. N-Methyllevamisole and p-bromolevamisole proved more effective than the parent compound, (S)-levamisole hydrochloride, with respect to inhibition of angiogenesis and induction of undifferentiated cluster morphology in human umbilical vein endothelial cells grown in co...

  7. Selective sp3 C-H alkylation via polarity-match-based cross-coupling

    Science.gov (United States)

    Le, Chip; Liang, Yufan; Evans, Ryan W.; Li, Ximing; MacMillan, David W. C.

    2017-07-01

    The functionalization of carbon-hydrogen (C-H) bonds is one of the most attractive strategies for molecular construction in organic chemistry. The hydrogen atom is considered to be an ideal coupling handle, owing to its relative abundance in organic molecules and its availability for functionalization at almost any stage in a synthetic sequence. Although many C-H functionalization reactions involve C(sp3)-C(sp2) coupling, there is a growing demand for C-H alkylation reactions, wherein sp3 C-H bonds are replaced with sp3 C-alkyl groups. Here we describe a polarity-match-based selective sp3 C-H alkylation via the combination of photoredox, nickel and hydrogen-atom transfer catalysis. This methodology simultaneously uses three catalytic cycles to achieve hydridic C-H bond abstraction (enabled by polarity matching), alkyl halide oxidative addition, and reductive elimination to enable alkyl-alkyl fragment coupling. The sp3 C-H alkylation is highly selective for the α-C-H of amines, ethers and sulphides, which are commonly found in pharmaceutically relevant architectures. This cross-coupling protocol should enable broad synthetic applications in de novo synthesis and late-stage functionalization chemistry.

  8. Selective sp3 C-H alkylation via polarity-match-based cross-coupling.

    Science.gov (United States)

    Le, Chip; Liang, Yufan; Evans, Ryan W; Li, Ximing; MacMillan, David W C

    2017-07-06

    The functionalization of carbon-hydrogen (C-H) bonds is one of the most attractive strategies for molecular construction in organic chemistry. The hydrogen atom is considered to be an ideal coupling handle, owing to its relative abundance in organic molecules and its availability for functionalization at almost any stage in a synthetic sequence. Although many C-H functionalization reactions involve C(sp 3 )-C(sp 2 ) coupling, there is a growing demand for C-H alkylation reactions, wherein sp 3 C-H bonds are replaced with sp 3 C-alkyl groups. Here we describe a polarity-match-based selective sp 3 C-H alkylation via the combination of photoredox, nickel and hydrogen-atom transfer catalysis. This methodology simultaneously uses three catalytic cycles to achieve hydridic C-H bond abstraction (enabled by polarity matching), alkyl halide oxidative addition, and reductive elimination to enable alkyl-alkyl fragment coupling. The sp 3 C-H alkylation is highly selective for the α-C-H of amines, ethers and sulphides, which are commonly found in pharmaceutically relevant architectures. This cross-coupling protocol should enable broad synthetic applications in de novo synthesis and late-stage functionalization chemistry.

  9. Targeting the plasma membrane of neoplastic cells through alkylation: a novel approach to cancer chemotherapy.

    Science.gov (United States)

    Trendowski, Matthew; Fondy, Thomas P

    2015-08-01

    Although DNA-directed alkylating agents and related compounds have been a mainstay in chemotherapeutic protocols due to their ability to readily interfere with the rapid mitotic progression of malignant cells, their clinical utility is limited by DNA repair mechanisms and immunosuppression. However, the same destructive nature of alkylation can be reciprocated at the cell surface using novel plasma membrane alkylating agents. Plasma membrane alkylating agents have elicited long term survival in mammalian models challenged with carcinomas, sarcomas, and leukemias. Further, a specialized group of plasma membrane alkylating agents known as tetra-O-acetate haloacetamido carbohydrate analogs (Tet-OAHCs) potentiates a substantial leukocyte influx at the administration and primary tumor site, indicative of a potent immune response. The effects of plasma membrane alkylating agents may be further potentiated through the use of another novel class of chemotherapeutic agents, known as dihydroxyacetone phosphate (DHAP) inhibitors, since many cancer types are known to rely on the DHAP pathway for lipid synthesis. Despite these compelling data, preliminary clinical trials for plasma membrane-directed agents have yet to be considered. Therefore, this review is intended for academics and clinicians to postulate a novel approach of chemotherapy; altering critical malignant cell signaling at the plasma membrane surface through alkylation, thereby inducing irreversible changes to functions needed for cell survival.

  10. An Efficient Synthesis of 1-Alkyl-2-phenyl-4-quinolones from 2-Halobenzoic Acids

    International Nuclear Information System (INIS)

    Song, Yoon Ju; Choi, Jin Sun; Lee, Jae In

    2013-01-01

    The present method offers an efficient synthesis of 1-alkyl-2-phenyl-4-quinolones from 2-haloben-zoic acids. It has the advantages with respect to (i) synthesis of 2 equiv of alkynones 5 from 1 equiv of 4,6-pyrimidyl di(2-halobenzoates) 3, (ii) synthesis of versatile 1-alkyl-2-phenyl-4-quinolones in high overall yields, and (iii) use of readily available and cheap starting materials. Therefore, this method could be utilized as a practical synthesis of 1-alkyl-2-phenyl-4-quinolones. Several methods have been developed to synthesize 1-alkyl-2-phenyl-4-quinolones from 2'-substituted acetophenones, anilines, and 2-halobenzoyl chlorides as starting materials. The reaction of N-methylisatoic anhydride with the lithium enolate of an 4'-methoxyacetophenone afforded the 1-methyl-2-phenyl-4-quinolone in a short sequence, but the yield was low. N-(2-Acetylphenyl)benzamides, prepared by Friedel-Crafts acylation of N-phenyl benzamides with acetyl chloride or benzoylation of 2'-aminoacetophenones with benzoyl chlorides,8 were cyclized with potassium t-butoxide to yield 2-aryl-4-quinolones, which were further alkylated with alkyl iodides to give 1-alkyl-2-aryl-4-quinolones

  11. Synthesis and antitumor effect of new biological alkylating agents, isethionic acid esters.

    Science.gov (United States)

    Kawazoe, Y; Tamura, N

    1981-12-01

    New hydrophilic alkylating agents, isethionic acid esters, are proposed for use as synthetic biological alkylating agents. Methyl, ethyl, and isopropyl esters of isethionic acid were synthesized starting from isethionate and the corresponding alkyl bromides or iodides in good yields. This synthetic procedure might be generally applicable to syntheses of alkyl isethionates. The derivatives thus prepared were water-soluble, as expected, and their alkylating abilities were very similar to those of the corresponding methanesulfonates. Hence, isethinonic acid esters might be suitable for use as hydrophilic biological alkylating agents in place of methanesulfonates. In order to determine the effectiveness of isethionates as anticancer alkylating agents, 1,4-butanediol diisethionate was prepared as a model compound and its anticancer activities against adenocarcinoma 755, sarcoma 180, L1210, and P388 were compared with those of the corresponding methanesulfonate, busulfan. The isethionate was superior to busulfan in all the assay systems employed. 1,5-Pentanediol diisethionate was also prepared and assayed. The results were similar to those for the 1,4-butanediol analog. In conclusion, in the design of molecules for use as cancer chemotherapeutics, the isethionic acid ester group is worth considering, and may be preferable to other commonly used leaving groups, including methanesulfonic acid ester.

  12. Iminium ion chemistry of mitosene DNA alkylating agents. Enriched 13C NMR and isolation studies.

    Science.gov (United States)

    Ouyang, A; Skibo, E B

    2000-05-16

    Described herein is a study of the reductive alkylation chemistry of mitosene antitumor agents. We employed a 13C-enriched electrophilic center to probe the fate of the iminium ion resulting from reductive activation. The 13C-labeled center permitted the identification of complex products resulting from alkylation reactions. In the case of DNA reductive alkylation, the type and number of alkylation sites were readily assessed by 13C NMR. Although there has been much excellent work done in the area of mitosene chemistry and biochemistry, the present study provides a number of new findings: (1) The major fate of the iminium ion is head-to-tail polymerization, even in dilute solutions. (2) Dithionite reductive activation results in the formation of mitosene sulfite esters as well as the previously observed sulfonate adducts. (3) The mitosene iminium ion alkylates the adenosine 6-amino group as well as the guanosine 2-amino group. The identification of the latter adduct was greatly facilitated by the 13C-label at the electrophilic center. (4) The mitosene iminium ion alkylates DNA at both nitrogen and oxygen centers without any apparent base selectivity. The complexity of mitosene reductive alkylation of DNA will require continued adduct isolation studies.

  13. Aag DNA glycosylase promotes alkylation-induced tissue damage mediated by Parp1.

    Directory of Open Access Journals (Sweden)

    Jennifer A Calvo

    2013-04-01

    Full Text Available Alkylating agents comprise a major class of front-line cancer chemotherapeutic compounds, and while these agents effectively kill tumor cells, they also damage healthy tissues. Although base excision repair (BER is essential in repairing DNA alkylation damage, under certain conditions, initiation of BER can be detrimental. Here we illustrate that the alkyladenine DNA glycosylase (AAG mediates alkylation-induced tissue damage and whole-animal lethality following exposure to alkylating agents. Aag-dependent tissue damage, as observed in cerebellar granule cells, splenocytes, thymocytes, bone marrow cells, pancreatic β-cells, and retinal photoreceptor cells, was detected in wild-type mice, exacerbated in Aag transgenic mice, and completely suppressed in Aag⁻/⁻ mice. Additional genetic experiments dissected the effects of modulating both BER and Parp1 on alkylation sensitivity in mice and determined that Aag acts upstream of Parp1 in alkylation-induced tissue damage; in fact, cytotoxicity in WT and Aag transgenic mice was abrogated in the absence of Parp1. These results provide in vivo evidence that Aag-initiated BER may play a critical role in determining the side-effects of alkylating agent chemotherapies and that Parp1 plays a crucial role in Aag-mediated tissue damage.

  14. Quinone methides tethered to naphthalene diimides as selective G-quadruplex alkylating agents.

    Science.gov (United States)

    Di Antonio, Marco; Doria, Filippo; Richter, Sara N; Bertipaglia, Carolina; Mella, Mariella; Sissi, Claudia; Palumbo, Manlio; Freccero, Mauro

    2009-09-16

    We have developed novel G-quadruplex (G-4) ligand/alkylating hybrid structures, tethering the naphthalene diimide moiety to quaternary ammonium salts of Mannich bases, as quinone-methide precursors, activatable by mild thermal digestion (40 degrees C). The bis-substituted naphthalene diimides were efficiently synthesized, and their reactivity as activatable bis-alkylating agents was investigated in the presence of thiols and amines in aqueous buffered solutions. The electrophilic intermediate, quinone-methide, involved in the alkylation process was trapped, in the presence of ethyl vinyl ether, in a hetero Diels-Alder [4 + 2] cycloaddition reaction, yielding a substituted 2-ethoxychroman. The DNA recognition and alkylation properties of these new derivatives were investigated by gel electrophoresis, circular dichroism, and enzymatic assays. The alkylation process occurred preferentially on the G-4 structure in comparison to other DNA conformations. By dissecting reversible recognition and alkylation events, we found that the reversible process is a prerequisite to DNA alkylation, which in turn reinforces the G-quadruplex structural rearrangement.

  15. Persistence of DNA adducts, hypermutation and acquisition of cellular resistance to alkylating agents in glioblastoma.

    Science.gov (United States)

    Head, R J; Fay, M F; Cosgrove, L; Y C Fung, K; Rundle-Thiele, D; Martin, J H

    2017-12-02

    Glioblastoma is a lethal form of brain tumour usually treated by surgical resection followed by radiotherapy and an alkylating chemotherapeutic agent. Key to the success of this multimodal approach is maintaining apoptotic sensitivity of tumour cells to the alkylating agent. This initial treatment likely establishes conditions contributing to development of drug resistance as alkylating agents form the O 6 -methylguanine adduct. This activates the mismatch repair (MMR) process inducing apoptosis and mutagenesis. This review describes key juxtaposed drivers in the balance between alkylation induced mutagenesis and apoptosis. Mutations in MMR genes are the probable drivers for alkylation based drug resistance. Critical to this interaction are the dose-response and temporal interactions between adduct formation and MMR mutations. The precision in dose interval, dose-responses and temporal relationships dictate a role for alkylating agents in either promoting experimental tumour formation or inducing tumour cell death with chemotherapy. Importantly, this resultant loss of chemotherapeutic selective pressure provides opportunity to explore novel therapeutics and appropriate combinations to minimise alkylation based drug resistance and tumour relapse.

  16. Aag DNA glycosylase promotes alkylation-induced tissue damage mediated by Parp1.

    Science.gov (United States)

    Calvo, Jennifer A; Moroski-Erkul, Catherine A; Lake, Annabelle; Eichinger, Lindsey W; Shah, Dharini; Jhun, Iny; Limsirichai, Prajit; Bronson, Roderick T; Christiani, David C; Meira, Lisiane B; Samson, Leona D

    2013-04-01

    Alkylating agents comprise a major class of front-line cancer chemotherapeutic compounds, and while these agents effectively kill tumor cells, they also damage healthy tissues. Although base excision repair (BER) is essential in repairing DNA alkylation damage, under certain conditions, initiation of BER can be detrimental. Here we illustrate that the alkyladenine DNA glycosylase (AAG) mediates alkylation-induced tissue damage and whole-animal lethality following exposure to alkylating agents. Aag-dependent tissue damage, as observed in cerebellar granule cells, splenocytes, thymocytes, bone marrow cells, pancreatic β-cells, and retinal photoreceptor cells, was detected in wild-type mice, exacerbated in Aag transgenic mice, and completely suppressed in Aag⁻/⁻ mice. Additional genetic experiments dissected the effects of modulating both BER and Parp1 on alkylation sensitivity in mice and determined that Aag acts upstream of Parp1 in alkylation-induced tissue damage; in fact, cytotoxicity in WT and Aag transgenic mice was abrogated in the absence of Parp1. These results provide in vivo evidence that Aag-initiated BER may play a critical role in determining the side-effects of alkylating agent chemotherapies and that Parp1 plays a crucial role in Aag-mediated tissue damage.

  17. Photochemistry of alkyl bromides trapped in water ice films

    Science.gov (United States)

    Schrems, O.; Okaikwei, B.; Bluszcz, Th.

    2012-04-01

    Photochemical reactions of atmospheric trace gases taking place at the surface of atmospheric ice particles and in bulk ice are important in stratospheric and tropospheric chemistry but also in polar and alpine snowpack chemistry. Consequently, the understanding of the uptake und incorporation of atmospheric trace gases in water ice as well as their interactions with water molecules is very important for the understanding of processes which occur in ice particles and at the air/ice interface. Reactive atmospheric trace gases trapped in ice are subject of photochemical reactions when irradiated with solar UV radiation. Among such compounds bromine species are highly interesting due to their potential of depleting ozone both in the stratosphere and troposphere. Organic bromine gases can carry bromine to the stratosphere. Methyl bromide (CH3Br) is the largest bromine carrier to the stratosphere. It has both natural and anthropogenic sources. In this contribution we will present the results of our laboratory studies of alkyl bromides (methyl, bromide (CH3Br), dimethyl bromide (CH2Br2), n-propyl bromide (C3H7Br), 1,2-dibromoethane C2H4Br2)), trapped in water ice. We have simulated the UV photochemistry of these brominated alkanes isolated in ice films kept at 16 K and for comparison in solid argon matrices. The photoproducts formed in the ice have been identified by means of FTIR spectroscopy. Reflection absorption infrared spectroscopy (RAIRS) is especially useful to study nascent ice surfaces, kinetics of adsorption/decomposition, and heterogeneous catalysis. Among the observed photoproducts we could identify carbon monoxide and carbon dioxide for each alkyl bromide studied. The photoproduct HBr is dissociated in the bulk ice. Based on the experimental observations possible reaction mechanisms will be discussed.

  18. Metabolism and Biomarkers of Heterocyclic Aromatic Amines in Molecular Epidemiology Studies: Lessons Learned from Aromatic Amines

    Science.gov (United States)

    2011-01-01

    Aromatic amines and heterocyclic aromatic amines (HAAs) are structurally related classes of carcinogens that are formed during the combustion of tobacco or during the high-temperature cooking of meats. Both classes of procarcinogens undergo metabolic activation by N-hydroxylation of the exocyclic amine group, to produce a common proposed intermediate, the arylnitrenium ion, which is the critical metabolite implicated in toxicity and DNA damage. However, the biochemistry and chemical properties of these compounds are distinct and different biomarkers of aromatic amines and HAAs have been developed for human biomonitoring studies. Hemoglobin adducts have been extensively used as biomarkers to monitor occupational and environmental exposures to a number of aromatic amines; however, HAAs do not form hemoglobin adducts at appreciable levels and other biomarkers have been sought. A number of epidemiologic studies that have investigated dietary consumption of well-done meat in relation to various tumor sites reported a positive association between cancer risk and well-done meat consumption, although some studies have shown no associations between well-done meat and cancer risk. A major limiting factor in most epidemiological studies is the uncertainty in quantitative estimates of chronic exposure to HAAs and, thus, the association of HAAs formed in cooked meat and cancer risk has been difficult to establish. There is a critical need to establish long-term biomarkers of HAAs that can be implemented in molecular epidemioIogy studies. In this review article, we highlight and contrast the biochemistry of several prototypical carcinogenic aromatic amines and HAAs to which humans are chronically exposed. The biochemical properties and the impact of polymorphisms of the major xenobiotic-metabolizing enzymes on the biological effects of these chemicals are examined. Lastly, the analytical approaches that have been successfully employed to biomonitor aromatic amines and HAAs, and

  19. Characterization of reaction conditions providing rapid and specific cysteine alkylation for peptide-based mass spectrometry.

    Science.gov (United States)

    Paulech, Jana; Solis, Nestor; Cordwell, Stuart J

    2013-01-01

    Alkylation converts Cys thiols to thioethers and prevents unwanted side reactions, thus facilitating mass spectrometric identification of Cys-containing peptides. Alkylation occurs preferentially at Cys due to its high nucleophilicity, however reactions at other such sites are possible. N-ethylmaleimide (NEM) shows rapid reaction kinetics with Cys and careful definition of reaction conditions results in little reactivity at other sites. Analysis of a protein standard alkylated under differing reaction conditions (pH, NEM concentrations and reaction times) was performed using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) and selected reaction monitoring (SRM) of NEM-modified and unmodified peptide pairs. Mis-alkylation sites at primary and secondary amines were identified and limited to one equivalent of NEM. No evidence for hydroxyl or thioether alkylation was observed. Improved specificity was achieved by restricting the pH below neutral, NEM concentration below 10mM and/or reaction time to below 5min. Maximal removal of Cys activity was observed in tissue homogenates at 40mM NEM within 1min, dependent upon efficient protein denaturation. SRM assays identified peptide-specific levels of mis-alkylation, indicating that NEM-modified to unmodified ratios did not exceed 10%, with the exception of Cys alkylation that proceeded to 100%, and some Lys residues that resulted in tryptic missed cleavages. High reactivity was observed for His residues considering their relatively low abundance. These data indicate that rapid and specific Cys alkylation is possible with NEM under relatively mild conditions, with more abrasive conditions leading to increased non-specific alkylation without appreciable benefit for MS-based proteomics. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Current approaches to improve the anticancer chemotherapy with alkylating agents: state of the problem in world and Ukraine.

    Directory of Open Access Journals (Sweden)

    Iatsyshyna A. P.

    2012-01-01

    Full Text Available Alkylating agents are frequently used in many established anticancer chemotherapies. They alkylate the genomic DNA at various sites. Alkylation of the guanine at the O6-position is cytotoxic, it has the strongest mutagenic potential, as well as can cause the tumor development. Alkyl groups at the O6-position of guanine are removed by the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT. The effectiveness of alkylating chemotherapy is limited by MGMT in cancer cells and adverse toxic side effects in normal cells. Different approaches consisting in the modulation of the MGMT expression and activity are under development now to improve the cancer chemotherapy. They include two main directions, in particular, the increase in chemosensitivity of cancer cells to alkylating drugs and the protection of normal cells from the toxic side effects of chemotherapy. This review is focused on current attempts to improve the alkylating chemotherapy of malignant tumours worldwide and state of the issue in Ukraine

  1. A mild and efficient procedure for the synthesis of ethers from various alkyl halides

    Directory of Open Access Journals (Sweden)

    Mosstafa Kazemi

    2013-10-01

    Full Text Available A simple, mild and practical procedure has been developed for the synthesis of symmetrical and unsymmetrical ethers by using DMSO, TBAI in the presence of K2CO3. We extended the utility of Potassium carbonate as an efficient base for the preparation of ethers. A wide range of alkyl aryl and dialkyl ethers are synthezied from treatment of aliphatic alcohols and phenols with various alkyl halides in the prescence of efficient base Potassium carbonate. Secondary alkyl halides were easily converted to corresponding ethers in releatively good yields . This is a mild, simple and practical procedure for the preparation of ethers in high yields and suitable times under mild condition.

  2. Unexpected Retroaldol-Aldol Reaction during O-Alkylation of Hydroxylated Vince Lactam Derivatives.

    Science.gov (United States)

    Bengtsson, Christoffer; Wetzel, Alexander; Bergman, Joakim; Brånalt, Jonas

    2016-01-15

    The unexpected retroaldol-aldol reaction during O-alkylation of a β-hydroxy lactam was found to be highly dependent on the temperature and shows a remarkable solvent effect. In DMF, O-alkylation is faster than retroaldol-aldol rearrangement giving exclusively products with retention of configuration. In THF, O-alkylation is slower than rearrangement, giving selectively products with inversion of stereochemistry. In DMSO, a retroaldol reaction followed by fast intramolecular proton transfer occurs to give the ring-opened aldehyde.

  3. Boron-Catalyzed N-Alkylation of Amines using Carboxylic Acids.

    Science.gov (United States)

    Fu, Ming-Chen; Shang, Rui; Cheng, Wan-Min; Fu, Yao

    2015-07-27

    A boron-based catalyst was found to catalyze the straightforward alkylation of amines with readily available carboxylic acids in the presence of silane as the reducing agent. Various types of primary and secondary amines can be smoothly alkylated with good selectivity and good functional-group compatibility. This metal-free amine alkylation was successfully applied to the synthesis of three commercial medicinal compounds, Butenafine, Cinacalcet. and Piribedil, in a one-pot manner without using any metal catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Catalytic Alkylation of 2-Methylfuran with Formalin Using Supported Acidic Ionic Liquids

    DEFF Research Database (Denmark)

    Li, Hu; Shunmugavel, Saravanamurugan; Yang, Song

    2015-01-01

    Biphasic alkylation of 2-methylfuran (2-MF) with formalin was carried out with a series of SBA-15 supported acidic ionic liquid catalysts (acidic SILCs) under mild reaction conditions. Acidic SILC with sulfonic acid groups (SO3H) and long alkyl chains was observed to have higher catalytic activity...... than commercial sulfonic acid resin catalysts for the alkylation reaction in terms of TONs/TOFs as well as selectivity (90%) toward the C11 oxygenate bis(5-methylfuran-2-yl)methane (BMFM). The reaction product was easily separated by addition of the nonpolar solvent n-heptane and additional water...

  5. Stimulatory and protective effects of alkylating agents applied in ultra-low concentrations.

    Science.gov (United States)

    Pukhalsky, A L; Shmarina, G V

    2001-01-01

    Alkylating drugs belonging to the nitrogen mustard family are known as cytostatic and immunosuppressive agents. Ultra-low doses of these drugs may demonstrate pharmacological effects unlike this category of drugs. In the case of a gradual dose decrease, the number of targets for alkylation is also reduced and the drug switches from cytostatic to cell growth modifier. We postulate that application of ultra-low doses of alkylating drugs may result in a beneficial effect in the therapy of diseases associated with chronic inflammation of the mucosa, especially with the signs of epithelial atrophy. Copyright 2001 S. Karger AG, Basel

  6. Enzymatic production of alkyl esters through alcoholysis: A critical evaluation of lipases and alcohols

    DEFF Research Database (Denmark)

    Li, Deng; Xu, Xuebing; Gudmundur G, Haraldsson

    2005-01-01

    This paper focuses on a detailed evaluation of commercially available immobilized lipases and simple monohydric alcohols for the production of alkyl esters from sunflower oil by enzymatic alcoholysis. Six lipases were tested with seven alcohols, including straight and branched-chain primary...... yield of FA alkyl esters, with yields well over 90% for methanol, absolute ethanol, and 1-propanol. Overall, 96% ethanol was the preferred alcohol for all lipases except Novozym 435, and ethanolysis reactions reached the maximal conversion efficiency. Increasing the water content in the system resulted...... commercial immobilized lipases are highly efficient and promising for the production of alkyl esters, offering high reaction yields and a simple operation process....

  7. Aag-initiated base excision repair drives alkylation-induced retinal degeneration in mice.

    Science.gov (United States)

    Meira, Lisiane B; Moroski-Erkul, Catherine A; Green, Stephanie L; Calvo, Jennifer A; Bronson, Roderick T; Shah, Dharini; Samson, Leona D

    2009-01-20

    Vision loss affects >3 million Americans and many more people worldwide. Although predisposing genes have been identified their link to known environmental factors is unclear. In wild-type animals DNA alkylating agents induce photoreceptor apoptosis and severe retinal degeneration. Alkylation-induced retinal degeneration is totally suppressed in the absence of the DNA repair protein alkyladenine DNA glycosylase (Aag) in both differentiating and postmitotic retinas. Moreover, transgenic expression of Aag activity restores the alkylation sensitivity of photoreceptors in Aag null animals. Aag heterozygotes display an intermediate level of retinal degeneration, demonstrating haploinsufficiency and underscoring that Aag expression confers a dominant retinal degeneration phenotype.

  8. Atmosphere-Controlled Chemoselectivity: Rhodium-Catalyzed Alkylation and Olefination of Alkylnitriles with Alcohols.

    Science.gov (United States)

    Li, Junjun; Liu, Yuxuan; Tang, Weijun; Xue, Dong; Li, Chaoqun; Xiao, Jianliang; Wang, Chao

    2017-10-17

    The chemoselective alkylation and olefination of alkylnitriles with alcohols have been developed by simply controlling the reaction atmosphere. A binuclear rhodium complex catalyzes the alkylation reaction under argon through a hydrogen-borrowing pathway and the olefination reaction under oxygen through aerobic dehydrogenation. Broad substrate scope is demonstrated, permitting the synthesis of some important organic building blocks. Mechanistic studies suggest that the alkylation product may be formed through conjugate reduction of an alkene intermediate by a rhodium hydride, whereas the formation of olefin product may be due to the oxidation of the rhodium hydride complex with molecular oxygen. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Fugacity approach to evaluate the sediment-water diffusion of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Wang, De-Gao; Alaee, Mehran; Byer, Jonathan; Liu, Yong-Jun; Tian, Chong-Guo

    2011-06-01

    Diffusion is an important process for sediment-water exchange and plays a vital role in controlling water quality. Fugacity fraction (ff) was used to estimate the sediment-water diffusion of polycyclic aromatic hydrocarbons (PAHs) between seawater and surficial sediment. A total of 33 surface sediment and sea water samples were collected concurrently from the northeast coastal area in China and 25 PAHs were analyzed including the alkylated and chlorated PAHs. Fugacity fraction was calculated based on the PAH concentrations in water and sediment, octanol-water partition coefficient of PAHs, organic matter content in sediment, and density of sediment. The calculated results showed that ff increased with decreasing molecular weight of PAHs. The low molecular weight PAHs (2-3 rings) transferred from sediment to water and the sediment acted as a secondary source to the water. The medium molecular weight PAHs (4-5 rings) were close to the sediment-water equilibrium and the transfer tendency shifted between sediment and water. The high molecular weight PAHs (5-6 rings) transferred from water into sediment and the sediment acted as a sink. Soot carbon and the difference of PAH concentrations between sediment and water were found to be important factors affecting the sediment-water diffusion. This study provided new insight into the process of sediment-water diffusion, which has a great influence on the quality of water, especially in severely-polluted sediment areas.

  10. Impact of vegetation on sedimentary organic matter composition and polycyclic aromatic hydrocarbon attenuation.

    Science.gov (United States)

    Gregory, Samuel T; Shea, Damian; Guthrie-Nichols, Elizabeth

    2005-07-15

    Results from natural and engineered phytoremediation systems provide strong evidencethatvegetated soils mitigate polycyclic aromatic hydrocarbon (PAH) contamination. However, the mechanisms by which PAH mitigation occurs and the impact of plant organic matter on PAH attenuation remain unclear. This study assessed the impact of plant organic matter on PAH attenuation in labile and refractory sediments fractions from a petroleum distillate waste pit that has naturally revegetated. Samples were collected in distinct zones of barren and vegetated areas to assess changes to organic matter composition and PAH content as vegetation colonized and became established in the waste pit. Sediments were fractionated into bulk sediment and humin fractions and analyzed for organic matter composition by isotope ratio mass spectrometry (delta (13)C), 13C nuclear magnetic resonance (13C NMR), delta 14C AMS (accelerator mass spectrometry), and percent organic carbon (%TOC). Gas chromatography mass spectrometry (GC/ MS) of lipid extracts of SOM fractions provided data for PAH distribution histograms, compound weathering ratios, and alkylated and nonalkylated PAH concentrations. Inputs of biogenic plant carbon, PAH weathering, and declines in PAH concentrations are most evidentfor vegetated SOM fractions, particularly humin fractions. Sequestered PAH metabolites were also observed in vegetated humin. These results show that plant organic matter does impact PAH attenuation in both labile and refractory fractions of petroleum distillate waste.

  11. Far infrared (terahertz) spectroscopy of a series of polycyclic aromatic hydrocarbons and application to structure interpretation of asphaltenes and related compounds

    Science.gov (United States)

    Cataldo, Franco; Angelini, Giancarlo; García-Hernández, D. A.; Manchado, Arturo

    2013-07-01

    A series of 33 different polycyclic aromatic hydrocarbons (PAHs) were studied by far infrared spectroscopy (terahertz spectroscopy) in the spectral range comprised between 600 and 50 cm-1. In addition to common PAHs like naphthalene, anthracene, phenanthrene, fluoranthene, picene, pyrene, benzo[α]pyrene, and perylene, also quite unusual PAHs were studied like tetracene, pentacene, acenaphtene, acenaphtylene, triphenylene, and decacyclene. A series of alkylated naphthalenes and anthracenes were studied as well as methypyrene. Partially or totally hydrogenated PAHs were also object of the present investigation, ranging from tetrahydronaphthalene (tetralin) to decahydronaphthalene (decalin), 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, hexahydropyrene, and dodecahydrotriphenylene. Finally, the large and quite rare PAHs coronene, quaterrylene, hexabenzocoronene, and dicoronylene were studied by far infrared spectroscopy. The resulting reference spectra were used in the interpretation of the chemical structure of asphaltenes (as extracted from a heavy petroleum fraction and from bitumen), the chemical structures of other petroleum fractions known as DAE (distillate aromatic extract) and RAE (residual aromatic extract), and a possible interpretation of components of the chemical structure of anthracite coal. Asphaltenes, heavy petroleum fractions, and coal were proposed as model compounds for the interpretation of the emission spectra of certain proto-planetary nebulae (PPNe) with a good matching in the mid infrared between the band pattern of the PPNe emission spectra and the spectra of these oil fractions or coal. Although this study was finalized in an astrochemical context, it may find application also in the petroleum and coal chemistry.

  12. Distribution and sources of aliphatic and polycyclic aromatic hydrocarbons in surface sediments, fish and bivalves of Abu Qir Bay (Egyptian Mediterranean Sea).

    Science.gov (United States)

    El Deeb, Kamal Z; Said, Tarek O; El Naggar, Mohamed H; Shreadah, Mohamed A

    2007-05-01

    Polycyclic aromatic hydrocarbons (PAHs) were detected and quantified in recent marine sediments and selected species from fishes, bivalves and crustaceans of Abu Qir Bay during the period January-October 2004. Nineteen sampling stations were chosen to collect sediment samples covering almost the Bay area. Total PAHs found in the surficial bottom sediments of the Bay were identified in moderate values ranging between 69 and 1,464 ng/g dry weights. The distribution pattern of these compounds showed the availability of most di, tri- and tetra aromatics in the Bay area in addition to their alkyl derivatives. High molecular weight aromatic hydrocarbons of five or more ring were detected everywhere in the Bay sediments. Certain number of pairs of isomer PAH concentrations are used for five origin molecular indices to identify the PAH concentration sources in the sediments of the Bay: Fluo/Py, Fluo/[Fluo + Py], LMW/HMW, BbF/BaP and BkF/BaP. Abu Qir Bay sediment samples were contaminated mainly by pyrolytic and petrogenic contaminations with strong pyrolytic inputs in the southwestern basin, while the northeastern area of the Bay is contaminated mainly by petrogenic PAHs. The studied biota samples of the Bay revealed levels of moderately contaminated specimens with total PAHs, while the carcinogenic PAH, benzo(a)pyrene were detected in most biological samples in levels ranged between 30.3 and 358 ng/g with an average of 152.4 ng/g should be taken into consideration.

  13. Method of removing alkyl iodides or mixtures of iodine and alkyl iodides from a gas phase and an aqueous solution phase by utilizing ion exchange resins

    International Nuclear Information System (INIS)

    Shimizu, Hiroshi; Mizuuchi, Noboru; Yokoyama, Fumio.

    1967-01-01

    Alkyl iodides and mixtures of iodine and alkyl iodides are removed from a gas phase and an aquous solution phase by using solely an anion exchange resin containing a tertiary amine or together with an anion exchange resin containing quarternary ammonium compound. The resin containing the quarternary ammonium compound is employed mainly to remove iodine, and the resin containing the tertiary amine serves mainly to remove alkyl iodides. The method can be applied to collecting a majority of the methyl iodide as well as the radioactive iodine produced in the atmosphere of a reactor in case of a fuel accident. In embodiments, it is desirable to maintain the sufficient moisture content of the anion exchange resins at a sufficient moisture level so as not to reduce the migration speed of the iodine and alkyl iodides. The iodine and alkyl iodide can be produced with high efficiency and stability independently of the relative humidity of the gas phase. In examples, a solution which consists of 20.5 mg/l of iodine and 42.2mg/l of methyl iodide flew through a column of Amberite IRA-93 alone or blended with IRA-900 at a speed of 15 /hr. respectively. The resins were able to treat 400 times their equivalent in water. (Iwakiri, K.)

  14. Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases; Part 1: alkyl halide alkylations.

    Science.gov (United States)

    Sorochinsky, Alexander E; Aceña, José Luis; Moriwaki, Hiroki; Sato, Tatsunori; Soloshonok, Vadim A

    2013-10-01

    Alkylations of chiral or achiral Ni(II) complexes of glycine Schiff bases constitute a landmark in the development of practical methodology for asymmetric synthesis of α-amino acids. Straightforward, easy preparation as well as high reactivity of these Ni(II) complexes render them ready available and inexpensive glycine equivalents for preparing a wide variety of α-amino acids, in particular on a relatively large scale. In the case of Ni(II) complexes containing benzylproline moiety as a chiral auxiliary, their alkylation proceeds with high thermodynamically controlled diastereoselectivity. Similar type of Ni(II) complexes derived from alanine can also be used for alkylation providing convenient access to quaternary, α,α-disubstituted α-amino acids. Achiral type of Ni(II) complexes can be prepared from picolinic acid or via recently developed modular approach using simple secondary or primary amines. These Ni(II) complexes can be easily mono/bis-alkylated under homogeneous or phase-transfer catalysis conditions. Origin of diastereo-/enantioselectivity in the alkylations reactions, aspects of practicality, generality and limitations of this methodology is critically discussed.

  15. Six-Membered Aromatic Polyazides: Synthesis and Application

    OpenAIRE

    Sergei V. Chapyshev

    2015-01-01

    Aromatic polyazides are widely used as starting materials in organic synthesis and photochemical studies, as well as photoresists in microelectronics and as cross-linking agents in polymer chemistry. Some aromatic polyazides possess high antitumor activity, while many others are of considerable interest as high-energy materials and precursors of high-spin nitrenes and C3N4 carbon nitride nanomaterials. The use of aromatic polyazides in click-reactions may be a new promising direction in the d...

  16. Mechanisms for polycyclic aromatic hydrocarbon degradation by ligninolytic fungi.

    OpenAIRE

    Hammel, K E

    1995-01-01

    Ligninolytic fungi accomplish the partial degradation of numerous aromatic organopollutants. Their ability to degrade polycyclic aromatic hydrocarbons (PAHs) is particularly interesting because eukaryotes were previously considered to be unable to cleave fused-ring aromatics. Recent results indicate that extracellular peroxidases of these fungi are responsible for the initial oxidation of PAHs. Fungal lignin peroxidases oxidize certain PAHs directly, whereas fungal manganese peroxidases co-ox...

  17. Aromatic plant production on metal contaminated soils

    International Nuclear Information System (INIS)

    Zheljazkov, Valtcho D.; Craker, Lyle E.; Xing Baoshan; Nielsen, Niels E.; Wilcox, Andrew

    2008-01-01

    Field and container experiments were conducted to assess the feasibility of growing aromatic crops in metal contaminated areas and the effect of metals on herbage and oil productivity. The field experiments were conducted in the vicinities of the Non-Ferrous Metals Combine (Zn-Cu smelter) near Plovdiv, Bulgaria using coriander, sage, dill, basil, hyssop, lemon balm, and chamomile grown at various distances from the smelter. Herbage essential oil yields of basil, chamomile, dill, and sage were reduced when they were grown closer to the smelter. Metal removal from the site with the harvestable plant parts was as high as 180 g ha -1 for Cd, 660 g ha -1 for Pb, 180 g ha -1 for Cu, 350 g ha -1 for Mn, and 205 g ha -1 for Zn. Sequential extraction of soil demonstrated that metal fractionation was affected by the distance to the smelter. With decreasing distance to the smelter, the transfer factor (TF) for Cu and Zn decreased but increased for Cd, while the bioavailability factor (BF) for Cd, Pb, Cu, Mn, and Zn decreased. Scanning electron microscopy and X-ray microanalyses of contaminated soil verified that most of the Pb, Cd, Mn, Cu, and Zn were in the form of small (< 1 μm) particles, although there were larger particles (1-5 μm) with high concentrations of individual metals. This study demonstrated that high concentrations of heavy metals in soil or growth medium did not result in metal transfer into the essential oil. Of the tested metals, only Cu at high concentrations may reduce oil content. Our results demonstrated that aromatic crops may not have significant phytoremediation potential, but growth of these crops in metal contaminated agricultural soils is a feasible alternative. Aromatic crops can provide economic return and metal-free final product, the essential oil

  18. Aromatic plant production on metal contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Zheljazkov, Valtcho D. [Mississippi State, Department of Plant and Soil Sciences and North Mississippi Research and Extension Center, 5421 Highway 145 South, Verona, MS 38879 (United States)], E-mail: vj40@pss.msstate.edu; Craker, Lyle E.; Xing Baoshan [Department of Plant and Soil Sciences, 12 Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States); Nielsen, Niels E. [Plant Nutrition and Soil Fertility Lab, Department of Agricultural Sciences, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK1871, Copenhagen (Denmark); Wilcox, Andrew [Harper Adams University College, Newport, Shropshire, TF10 8NB (United Kingdom)

    2008-06-01

    Field and container experiments were conducted to assess the feasibility of growing aromatic crops in metal contaminated areas and the effect of metals on herbage and oil productivity. The field experiments were conducted in the vicinities of the Non-Ferrous Metals Combine (Zn-Cu smelter) near Plovdiv, Bulgaria using coriander, sage, dill, basil, hyssop, lemon balm, and chamomile grown at various distances from the smelter. Herbage essential oil yields of basil, chamomile, dill, and sage were reduced when they were grown closer to the smelter. Metal removal from the site with the harvestable plant parts was as high as 180 g ha{sup -1} for Cd, 660 g ha{sup -1} for Pb, 180 g ha{sup -1} for Cu, 350 g ha{sup -1} for Mn, and 205 g ha{sup -1} for Zn. Sequential extraction of soil demonstrated that metal fractionation was affected by the distance to the smelter. With decreasing distance to the smelter, the transfer factor (TF) for Cu and Zn decreased but increased for Cd, while the bioavailability factor (BF) for Cd, Pb, Cu, Mn, and Zn decreased. Scanning electron microscopy and X-ray microanalyses of contaminated soil verified that most of the Pb, Cd, Mn, Cu, and Zn were in the form of small (< 1 {mu}m) particles, although there were larger particles (1-5 {mu}m) with high concentrations of individual metals. This study demonstrated that high concentrations of heavy metals in soil or growth medium did not result in metal transfer into the essential oil. Of the tested metals, only Cu at high concentrations may reduce oil content. Our results demonstrated that aromatic crops may not have significant phytoremediation potential, but growth of these crops in metal contaminated agricultural soils is a feasible alternative. Aromatic crops can provide economic return and metal-free final product, the essential oil.

  19. Aromatic plant production on metal contaminated soils.

    Science.gov (United States)

    Zheljazkov, Valtcho D; Craker, Lyle E; Xing, Baoshan; Nielsen, Niels E; Wilcox, Andrew

    2008-06-01

    Field and container experiments were conducted to assess the feasibility of growing aromatic crops in metal contaminated areas and the effect of metals on herbage and oil productivity. The field experiments were conducted in the vicinities of the Non-Ferrous Metals Combine (Zn-Cu smelter) near Plovdiv, Bulgaria using coriander, sage, dill, basil, hyssop, lemon balm, and chamomile grown at various distances from the smelter. Herbage essential oil yields of basil, chamomile, dill, and sage were reduced when they were grown closer to the smelter. Metal removal from the site with the harvestable plant parts was as high as 180 g ha(-1) for Cd, 660 g ha(-1) for Pb, 180 g ha(-1) for Cu, 350 g ha(-1) for Mn, and 205 g ha(-1) for Zn. Sequential extraction of soil demonstrated that metal fractionation was affected by the distance to the smelter. With decreasing distance to the smelter, the transfer factor (TF) for Cu and Zn decreased but increased for Cd, while the bioavailability factor (BF) for Cd, Pb, Cu, Mn, and Zn decreased. Scanning electron microscopy and X-ray microanalyses of contaminated soil verified that most of the Pb, Cd, Mn, Cu, and Zn were in the form of small (metals. This study demonstrated that high concentrations of heavy metals in soil or growth medium did not result in metal transfer into the essential oil. Of the tested metals, only Cu at high concentrations may reduce oil content. Our results demonstrated that aromatic crops may not have significant phytoremediation potential, but growth of these crops in metal contaminated agricultural soils is a feasible alternative. Aromatic crops can provide economic return and metal-free final product, the essential oil.

  20. Petroleum and individual polycyclic aromatic hydrocarbons

    Science.gov (United States)

    Albers, Peter H.; Hoffman, David J.; Rattner, Barnett A.; Burton, G. Allen; Cairns, John

    1995-01-01

    Crude petroleum, refined-petroleum products, and individual polycyclic aromatic hydrocarbons (PAHs) contained within petroleum are found throughout the world. their presence has been detected in living and nonliving components of ecosystems. Petroleum can be an environmental hazard for wild animals and plants. Individual PAHs are also hazardous to wildlife, but they are most commonly associated with human illnesses. Because petroleum is a major environmental source of these PAHs, petroleum and PAHs are jointly presented in this chapter. Composition, sources, environmental fate, and toxic effects on all living components of aquatic and terrestrial environments are addessed.

  1. Polycyclic aromatic hydrocarbons profile of kitchen dusts.

    Science.gov (United States)

    Iwegbue, Chukwujindu M A

    2011-03-01

    Concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) were determined in thirty dust samples collected from kitchens that use wood cook system (WCS), kerosene stove cook system (KSCS) and butane gas cook system (BGCS). The total PAHs concentrations ranged from 52 to 497, 39 to 96 and 37 to 155 μg kg(-1) for WCS, KSCS and BGCS respectively. The results indicate predominance of lower molecular weight (2-3 rings) over higher molecular weight PAHs and users of wood cook system are more exposed to higher levels of PAHs than the users of either kerosene cook system or butane gas cook system.

  2. Aromatics oxidation and soot formation in flames

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T. [Massachusetts Institute of Technology, Cambridge (United States)

    1993-12-01

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and soot and fullerenes formation in flames. The scope includes detailed measurements of profiles of stable and radical species concentrations in low-pressure one-dimensional premixed flames. Intermediate species identifications and mole fractions, fluxes, and net reaction rates calculated from the measured profiles are used to test postulated reaction mechanisms. Particular objectives are to identify and to determine or confirm rate constants for the main benzene oxidation reactions in flames, and to characterize fullerenes and their formation mechanisms and kinetics.

  3. Microbial degradation of polycyclic aromatic hydrocarbons

    International Nuclear Information System (INIS)

    Volkering, F.; Breure, A.M.; Andel, J.G. van

    1992-01-01

    Polycyclic aromatic hydrocarbons (PAH) are hazardous compounds originating from oil, tar, creosote, or from incomplete combustion of fossil fuels. Application of biotechnological techniques for remediation of polluted soils from PAH demonstrated that the high molecular compounds are degraded very slowly, and that the residual concentration of PAH often is too high to permit application of the treated soil. Investigations were started to establish process parameters for optimal biodegradation of PAH. The aim is to achieve a relation between the physical properties of PAH and the biodegradation kinetics in different matrices, in order to identify applicability of biotechnological cleanup methods for waste streams and polluted soil. (orig.) [de

  4. Aromatic metabolism of filamentous fungi in relation to the presence of aromatic compounds in plant biomass

    NARCIS (Netherlands)

    Mäkelä, Miia R; Marinović, Mila; Nousiainen, Paula; Liwanag, April J M; Benoit, Isabelle; Sipilä, Jussi; Hatakka, Annele; de Vries, Ronald P; Hildén, Kristiina S

    2015-01-01

    The biological conversion of plant lignocellulose plays an essential role not only in carbon cycling in terrestrial ecosystems but also is an important part of the production of second generation biofuels and biochemicals. The presence of the recalcitrant aromatic polymer lignin is one of the major

  5. Source characterization of polycyclic aromatic hydrocarbons by using their molecular indices: an overview of possibilities.

    Science.gov (United States)

    Stogiannidis, Efstathios; Laane, Remi

    2015-01-01

    In recent decades. an exponential increase in the concentration of anthropogenic Polycyclic Aromatic Hydrocarbons (PAHs; see Table I for a li st of PAH abbreviations) has been observed worldwide. Regulators need to know the sources if concentrations are to be reduced and appropriate remediation measures taken. "Source characterization of PAHs" involves linking these contaminants to their sources. Scientists place PAH sources into three classes: pyrogenic, petrogenic. and natural. In this review. we investigate the possibility of using PAH molecular ratios individually or in combination for the purpose of deducing the petrogenic or pyrogenic origin of the contamination in sediments. We do this by reviewing the characteristic PAH patterns of the sources and by taking into account the fate of PAHs in the aquatic environment. Many PAH indicators have been developed for the purpose of discriminating different PAH sources. In Table 4 we summarize the applicability of different PAH ratios and threshold values. The analysis of two- to four-ringed alkylated PAH soilers the possibility to distinguish two or more single sources or categories of pollution in greater detail. For example. the FLO/PYO. the PPI. and PO/AO ratios can be used to discriminate between pyrogenic and petrogcnic sources of contamination. When petrogenic contamination is suspected. chrysenes. PAHs lighter than CO. and in particular. alkylated PAHs can usually be of use. For unburned coal PAHs. The methylphenanthrenic ratios (MP!s). the 1-D I/4- DI. and BbF/BkF are promising, since they are sometimes correlated with vitrinite rellectance (coal ranks). Alkylphenanthrenes can be used to detect biomass combustion. Higher molecular weight parent and alkylated PAHs are appropriate for pyrogenic discriminations. When PAH indices are coupled with discriminant analysis techniques such as PMF (positive matrix factorization),the origin of multiple sources in even the most complex environments can be traced and

  6. Phosphorus-containing podands. 14. Effect of alkyl substituents at phosphorus atom on complexing ability of neutral monopodands. On the nature of abnormal alkyl effect

    International Nuclear Information System (INIS)

    Tsvetkov, E.N.; Evreinov, V.I.; Bondarenko, N.A.; Safronova, Z.V.

    1996-01-01

    The previously revealed unusual effect of alkyl substituents at phosphorus atom in phosphorus-containing monopodands of the general formula o-R 2 P(O)C 6 H 4 (OCH 2 CH 2 ) n OC 6 H 4 P(O)R 2 -o, n=1-5, R = Alk, Ph, OEt on their complexing ability towards alkali metals cations has been interpreted. Alkyl radicals create great spatial obstacles to rotation of R 2 P(O) fragments around the C-P bond as compared with other substituents, which gives rise to the appearance of anomalous alkyl effect. Solvation is an additional factor, which can bring about the anomalous effect appearance or a change in the degree of its pronouncement. 47 refs.; 3 figs.; 7 tabs

  7. Alkyl chain length impacts the antioxidative effect of lipophilized ferulic acid in fish oil enriched milk

    DEFF Research Database (Denmark)

    Sørensen, Ann-Dorit Moltke; Lyneborg, Karina Sieron; Villeneuve, Pierre

    2015-01-01

    Lipophilization of phenolics by esterification with fatty alcohols may alter their localization in an emulsion and thereby their antioxidant efficacy. In this study, synthesized unbranched alkyl ferulates were evaluated as antioxidants in fish oil enriched milk. Lipid oxidation was determined...

  8. Study on the Alkylation Reactions of N(7)-Unsubstituted 1,3-Diazaoxindoles.

    Science.gov (United States)

    Kókai, Eszter; Halász, Judit; Dancsó, András; Nagy, József; Simig, Gyula; Volk, Balázs

    2017-05-19

    The chemistry of the 5,7-dihydro-6 H -pyrrolo[2,3- d ]pyrimidin-6-one (1,3-diazaoxindole) compound family, possessing a drug-like scaffold, is unexplored. In this study, the alkylation reactions of N (7)-unsubstituted 5-isopropyl-1,3-diazaoxindoles bearing various substituents at the C (2) position have been investigated. The starting compounds were synthesized from the C (5)-unsubstituted parent compounds by condensation with acetone and subsequent catalytic reduction of the 5-isopropylidene moiety. Alkylation of the thus obtained 5-isopropyl derivatives with methyl iodide or benzyl bromide in the presence of a large excess of sodium hydroxide led to 5,7-disubstituted derivatives. Use of butyllithium as the base rendered alkylation in the C (5) position possible with reasonable selectivity, without affecting the N (7) atom. During the study on the alkylation reactions, some interesting by-products were also isolated and characterized.

  9. Small-scale one -pot reductive alkylation of unprotected aminocyclitols with supported reagents

    Czech Academy of Sciences Publication Activity Database

    Šíša, Miroslav; Trapero, A.; Llebaria, A.; Delgado, A.

    -, č. 19 (2008), s. 3167-3170 ISSN 0039-7881 Institutional research plan: CEZ:AV0Z40550506 Keywords : alkylation s * aldehydes * supported reagents * aminocyclitols Subject RIV: CC - Organic Chemistry Impact factor: 2.470, year: 2008

  10. Synthesis of no-carrier-added radiobrominated n-alkylated analogues of spiperone

    International Nuclear Information System (INIS)

    Moerlein, S.M.; Laufer, P.; Stoecklin, G.

    1985-01-01

    The synthesis of a series of p-bromo-3-N-alkyl spiperone analogues is described. N-alkylation was achieved via reaction of the potassium salt of the spiperone lactam ring with alkyl iodide; subsequent reactions with elemental bromine gave the p-brominated isomers. Optimization studies using no-carrier-added (n.c.a.) 77 Br - indicated that radio-bromination of N-alkyl spiperone analogues occurs with higher yields and in shorter reaction times when dichloramine-T (DCT) is used rather than H 2 0 2 /acetic acid as an oxidant. The production of the title compounds in high effective specific activity with radiochemical yields of 20-30 % using n.c.a. 77 Br - and DCT is reported. (author)

  11. Electrochemistry of potentially bioreductive alkylating quinones. Part 3. Quantitative structure-electrochemistry relationships of aziridinylquinones

    NARCIS (Netherlands)

    Driebergen, R.J.; Moret, E.E.; Janssen, L.H.M.; Blauw, J.S.; Holthuis, J.J.M.; Postma kelder, S.J.; Verboom, Willem; Reinhoudt, David; van der Linden, W.E.

    1992-01-01

    The concept of bioreductive alkylation as a mechanism of action of aziridinylquinoid anticancer agents has been investigated by the use of electrochemical techniques. Properly substituted aziridinylquinones are activated by an electrochemical step (reduction of the quinone function), followed by

  12. Alkyl cross-linked low molecular weight polypropyleneimine dendrimers as efficient gene delivery vectors

    Directory of Open Access Journals (Sweden)

    Faezeh Moghadam Ariaee

    2016-10-01

    Conclusion: Our results indicated that oligomerization of low molecular weight PPI (PPI G2-alkyl-PPI G2 conjugate could be an approach to increase the transfection efficiency and to lower the cytotoxicity of low molecular weight polycations.

  13. Effect of alkyl length of cationic surfactants on desorption of Cs from contaminated clay

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo Hyun; Park, Chan Woo; Yang, Hee Man; Seo, Bum Kyoung; Lee, Kune Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, So Jin [Chungnam National University, Daejeon (Korea, Republic of)

    2017-03-15

    In this study, desorption characteristics of Cs from clay according to the hydrophobic alkyl chain length of the cationic surfactant were investigated. Alkyltrimethylammonium bromide was used as a cationic surfactant, and the length of the hydrophobic alkyl chain of the cationic surfactant was varied from –octyl to –cetyl. The adsorbed amount of the cationic surfactant on montmorillonite increased with the length of the hydrophobic alkyl chain, and intercalation of the cationic surfactant into the clay interlayer increased the interlayer distances. The Cs removal efficiency was also enhanced with increasing alkyl chain length, and the cationic surfactant with the cetyl group showed a maximum Cs removal efficiency of 99±2.9%.

  14. Tribochemistry of Multiply-Alkylated Cyclopentane Oils on DLC-Coated Thrust Bearings

    National Research Council Canada - National Science Library

    Lince, Jeffrey R; Bertrand, Patricia A

    2007-01-01

    .... We have conducted a study of H-DLC-coated steel thrust bearings, lubricated with a multiply-alkylated cyclopentane oil, either unformulated, or formulated with lead naphthenate or an aryl phosphate ester mixture...

  15. DNA alkylation damage as a sensor of nitrosative stress in Mycobacterium tuberculosis

    OpenAIRE

    Durbach, S I; Springer, B; Machowski, E E; North, R J; Papavinasasundaram, K G; Colston, M J; Böttger, E C; Mizrahi, V

    2003-01-01

    One of the cellular consequences of nitrosative stress is alkylation damage to DNA. To assess whether nitrosative stress is registered on the genome of Mycobacterium tuberculosis, mutants lacking an alkylation damage repair and reversal operon were constructed. Although hypersensitive to the genotoxic effects of N-methyl-N′-nitro-N-nitrosoguanidine in vitro, the mutants displayed no phenotype in vivo, suggesting that permeation of nitrosative stress to the level of cytotoxic DNA damage is res...

  16. Copper(II)/amine synergistically catalyzed enantioselective alkylation of cyclic N-acyl hemiaminals with aldehydes.

    Science.gov (United States)

    Sun, Shutao; Mao, Ying; Lou, Hongxiang; Liu, Lei

    2015-07-07

    The first catalytic asymmetric alkylation of N-acyl quinoliniums with aldehydes has been described. A copper/amine synergistic catalytic system has been developed, allowing the addition of functionalized aldehydes to a wide range of electronically varied N-acyl quinoliniums in good yields with excellent enantiocontrol. The synergistic catalytic system was also effective for N-acyl dihydroisoquinoliniums and β-caboliniums, demonstrating the general applicability of the protocol in the enantioselective alkylation of diverse cyclic N-acyl hemiaminals.

  17. Alkylation of human hair keratin for tunable hydrogel erosion and drug delivery in tissue engineering applications.

    Science.gov (United States)

    Han, Sangheon; Ham, Trevor R; Haque, Salma; Sparks, Jessica L; Saul, Justin M

    2015-09-01

    Polymeric biomaterials that provide a matrix for cell attachment and proliferation while achieving delivery of therapeutic agents are an important component of tissue engineering and regenerative medicine strategies. Keratins are a class of proteins that have received attention for numerous tissue engineering applications because, like other natural polymers, they promote favorable cell interactions and have non-toxic degradation products. Keratins can be extracted from various sources including human hair, and they are characterized by a high percentage of cysteine residues. Thiol groups on reductively extracted keratin (kerateine) form disulfide bonds, providing a more stable cross-linked hydrogel network than oxidatively extracted keratin (keratose) that cannot form disulfide crosslinks. We hypothesized that an iodoacetamide alkylation (or "capping") of cysteine thiol groups on the kerateine form of keratin could be used as a simple method to modulate the levels of disulfide crosslinking in keratin hydrogels, providing tunable rates of gel erosion and therapeutic agent release. After alkylation, the alkylated kerateines still formed hydrogels and the alkylation led to changes in the mechanical and visco-elastic properties of the materials consistent with loss of disulfide crosslinking. The alkylated kerateines did not lead to toxicity in MC3T3-E1 pre-osteoblasts. These cells adhered to keratin at levels comparable to fibronectin and greater than collagen. Alkylated kerateine gels eroded more rapidly than non-alkylated kerateine and this control over erosion led to tunable rates of delivery of rhBMP-2, rhIGF-1, and ciprofloxacin. These results demonstrate that alkylation of kerateine cysteine residues provides a cell-compatible approach to tune rates of hydrogel erosion and therapeutic agent release within the context of a naturally-derived polymeric system. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Melamine-bridged alkyl resorcinol modified urea - formaldehyde resin for bonding hardwood plywood

    Science.gov (United States)

    Chung-Yun Hse; Mitsuo Higuchi

    2010-01-01

    A powdery product was obtained by the reaction of methylolated melamine with alkyl resorcinols to form melamine-bridged alkyl resorcinols (MARs). The effects of the addition of this powder on the bonding strength and formaldehyde emission of urea–formaldehyde (UF) resins were investigated. Three types of UF resins with a formaldehyde/urea molar ratio of 1.3 synthesized...

  19. Cytotoxic geranylated xanthones and O-alkylated derivatives of alpha-mangostin

    DEFF Research Database (Denmark)

    Ha, Ly Dieu; Hansen, Poul Erik; Vang, Ole

    2009-01-01

    Two new geranylated xanthones, 6-O-methylcowanin (4) and oliverixanthone (5), along with five known compounds, cowanin, rubraxanthone, cowaxanthone, cowanol, and β-mangostin, have been isolated from the bark of Garcinia oliveri. For comparison of their biological activities, one mono- and seven di-O-alkylated...... that α-mangostin had the strongest activity, and all the O-alkylated α-mangostin derivatives showed reduced activity compared to the naturally occurring α-mangostin....

  20. Ruthenium-catalyzed direct C3 alkylation of indoles with α,β-unsaturated ketones.

    Science.gov (United States)

    Li, Shuai-Shuai; Lin, Hui; Zhang, Xiao-Mei; Dong, Lin

    2015-01-28

    In this paper, a simple and highly efficient ruthenium-catalyzed direct C3 alkylation of indoles with various α,β-unsaturated ketones without chelation assistance has been developed. This novel C-H activation methodology exhibits a broad substrate scope such as different substituted indoles, pyrroles, and other azoles. Further synthetic applications of the alkylation products can lead to more attractive 3,4-fused tricyclic indoles.