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Sample records for alkyl radicals

  1. 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)

  2. 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.

  3. 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...

  4. 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

  5. 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...

  6. 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

  7. Pulse radiolysis of alkanes: a time-resolved EPR study - Part I. Alkyl radicals

    International Nuclear Information System (INIS)

    Shkrob, I.A.; Trifunac, A.D.

    1995-01-01

    Time-resolved EPR was applied to detect short-lived alkyl radicals in pulse radiolysis of liquid alkanes. Two problems were addressed: (i) the mechanism of radical formation and (ii) the mechanism of chemically-induced spin polarization in these radicals. (i) The ratio of yields of penultimate and interior radicals in n-alkanes at the instant of their generation was found to be ≅ 1.25 times greater than the statistical quantity. This higher-than-statistical production of penultimate radicals indicates that the proton transfer reaction involving excited radical cations must be a prevailing route of radical generation. The relative yields of hydrogen abstraction and fragmentation for various branched alkanes are estimated. It is concluded that the fragmentation occurs prior to the formation of radicals in an excited precursor species. (ii) The analysis of spin-echo kinetics in n-alkanes suggests that the alkyl radicals gain the emissive polarization in spur reactions. This initial polarization increases with shortening of the aliphatic chain. We suggest that the origin of this polarization is the ST mechanism operating in the pairs of alkyl radicals and hydrogen atoms generated in dissociation of excited alkane molecules. It is also found that a long-chain structure of alkyl radicals results in much higher rate of Heisenberg spin exchange relative to the recombination rate (up to 30 times). That suggests prominent steric effects in recombination or the occurrence of through-chain electron exchange. The significance of these results in the context of cross-linking in polyethylene and higher paraffins is discussed. (Author)

  8. Application of visible-light photosensitization to form alkyl-radical-derived thin films on gold.

    Science.gov (United States)

    Quarels, Rashanique D; Zhai, Xianglin; Kuruppu, Neepa; Hedlund, Jenny K; Ellsworth, Ashley A; Walker, Amy V; Garno, Jayne C; Ragains, Justin R

    2017-01-01

    Visible-light irradiation of phthalimide esters in the presence of the photosensitizer [Ru(bpy) 3 ] 2+ and the stoichiometric reducing agent benzyl nicotinamide results in the formation of alkyl radicals under mild conditions. This approach to radical generation has proven useful for the synthesis of small organic molecules. Herein, we demonstrate for the first time the visible-light photosensitized deposition of robust alkyl thin films on Au surfaces using phthalimide esters as the alkyl radical precursors. In particular, we combine visible-light photosensitization with particle lithography to produce nanostructured thin films, the thickness of which can be measured easily using AFM cursor profiles. Analysis with AFM demonstrated that the films are robust and resistant to mechanical force while contact angle goniometry suggests a multilayered and disordered film structure. Analysis with IRRAS, XPS, and TOF SIMS provides further insights.

  9. Application of visible-light photosensitization to form alkyl-radical-derived thin films on gold

    Directory of Open Access Journals (Sweden)

    Rashanique D. Quarels

    2017-09-01

    Full Text Available Visible-light irradiation of phthalimide esters in the presence of the photosensitizer [Ru(bpy3]2+ and the stoichiometric reducing agent benzyl nicotinamide results in the formation of alkyl radicals under mild conditions. This approach to radical generation has proven useful for the synthesis of small organic molecules. Herein, we demonstrate for the first time the visible-light photosensitized deposition of robust alkyl thin films on Au surfaces using phthalimide esters as the alkyl radical precursors. In particular, we combine visible-light photosensitization with particle lithography to produce nanostructured thin films, the thickness of which can be measured easily using AFM cursor profiles. Analysis with AFM demonstrated that the films are robust and resistant to mechanical force while contact angle goniometry suggests a multilayered and disordered film structure. Analysis with IRRAS, XPS, and TOF SIMS provides further insights.

  10. Transients observed in the low temperature photolysis of alkyl radicals and divalent sulfur substrates

    International Nuclear Information System (INIS)

    The 253.7 nm photolysis of the isometric butyl radicals is described. These radicals are produced by electron capture during the γ-radiolysis of the corresponding butyl chlorides diluted in a rigid glass of 3-methylpentane-d14 at 77K. Thus t-butyl gives an equilibrium mixture of i-butyl and methyl radicals. Solvent radicals, M, are also produced and these obscure the former species in 3-MP-h14. Likewise sec-butyl radicals give rise to the ethyl, n-butyl, methyl and small amounts of the i-butyl radicals. Solvent radicals also rearrange and degrade in the photolytic beam, and the mechanism by which these processes occur is discussed. The procedure has also been used to study the formation and photolability of the alkyl thinyl and perthyl radicals occuring in the photolysis of RSH, RSR and RSSR. The thinyl radical is found to be unstable and gives the alkyl radical and atomic sulfur while the perthiyl radical is stable to radiation > 240 nm. (author)

  11. 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....

  12. Effect of solid phase on the selectivity of alkyl radical formation by gamma-irradiation of branched alkanes

    International Nuclear Information System (INIS)

    Koizumi, Hitoshi; Hashino, Masatoshi; Ichikawa, Tsuneki; Yoshida, Hiroshi

    1992-01-01

    ESR and electron spin echo measurements of alkyl radicals generated by γ-irradiation of glassy and crystalline branched alkanes C 10 ∼ C 13 have been carried out to elucidate the effect of molecular structure and solid phase on the selectivity of alkyl radical formation. Alkyl radicals generated and stabilized at 77 K in the glassy alkanes are secondary penultimate radicals. Tertiary radicals and secondary radicals other than the penultimate one are not generated either by hydrogen abstraction or from ionized or excited molecules. In the crystalline alkanes, however, a small amount of secondary internal radicals are generated in addition to the predominant formation of the secondary penultimate radicals. It is concluded that the detachment of C-H hydrogen preferentially takes place at the location where the motion of carbon atoms assisting the detachment of the C-H hydrogen easily occurs. (author)

  13. 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

  14. Reaction rates of glutathione and ascorbate with alkyl radicals are too slow for protection against protein peroxidation in vivo.

    Science.gov (United States)

    Nauser, Thomas; Gebicki, Janusz M

    2017-11-01

    Reaction kinetics of amino acid and peptide alkyl radicals with GSH and ascorbate, the two most abundant endogenous antioxidants, were investigated by pulse radiolysis. Rate constants in the order of 10 6  M -1 s -1 were found. Alkyl radicals react at almost diffusion controlled rates and irreversibly with oxygen to form peroxyl radicals, and competition with this reaction is the benchmark for efficient repair in vivo. We consider repair of protein radicals and assume comparable rate constants for the reactions of GSH/ascorbate with peptide alkyl radicals and with alkyl radicals on a protein surface. Given physiological concentrations of oxygen, GSH and ascorbate, protein peroxyl radicals will always be a major product of protein alkyl radicals in vivo. Therefore, if they are formed by oxidative stress, protein alkyl radicals are a probable cause for biological damage. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Improved simplified scheme of atom equivalents to calculate enthalpies of formation of alkyl radicals

    International Nuclear Information System (INIS)

    Castro, Eduardo A.

    2002-01-01

    An improved simplified method of atom equivalents is applied to the calculation of enthalpies of formation of several alkyl radicals. Some statistical mechanics and thermodynamic corrections are added to compare theoretical values with available experimental data. The estimation is quite satisfactory and the average error is similar to current experimental uncertainties, thus providing a direct and simple procedure for this sort of calculation when experimental results are unavailable or/and as an independent check when experimental data are in doubt. (Author) [es

  16. Mild and Low-Pressure fac-Ir(ppy)3 -Mediated Radical Aminocarbonylation of Unactivated Alkyl Iodides through Visible-Light Photoredox Catalysis.

    Science.gov (United States)

    Chow, Shiao Y; Stevens, Marc Y; Åkerbladh, Linda; Bergman, Sara; Odell, Luke R

    2016-06-27

    A novel, mild and facile preparation of alkyl amides from unactivated alkyl iodides employing a fac-Ir(ppy)3 -catalyzed radical aminocarbonylation protocol has been developed. Using a two-chambered system, alkyl iodides, fac-Ir(ppy)3 , amines, reductants, and CO gas (released ex situ from Mo(CO)6 ), were combined and subjected to an initial radical reductive dehalogenation generating alkyl radicals, and a subsequent aminocarbonylation with amines affording a wide range of alkyl amides in moderate to excellent yields. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Conformational analysis of the EPR spectra of cyclohexenyl radical and some of its alkyl derivatives

    International Nuclear Information System (INIS)

    de Tannoux, N.M.

    1975-01-01

    Electron paramagnetic resonance spectra have been obtained for radicals produced by x-irradiation of cyclohexene and various alkyl-substituted cyclohexenes trapped in an adamantane matrix. Temperature variations of these spectra permits determination of the enthalpy and entropy of activation for interconversion between the conformations. For cyclohexenyl radical, the enthalpy of activation is 6.81 +- 0.58 kcal/mole and the entropy of activation is -0.04 +- 2.38 e.u. Methyl substitution on C 1 gives a radical with activation parameters similar to the parent radical. Methyl groups attached to C 5 increase the activation parameters significantly. On the basis of these observations, it is suggested the cyclohexenyl radicals exist in two conformations of the same energy which are of the ''envelope'' type, with C 1 , C 2 , C 3 , C 4 , and C 6 coplanar. A model involving a planar transition state for the interconversion process is proposed which accounts for most of the experimental results

  18. Alkyl hydrogen atom abstraction reactions of the CN radical with ethanol

    Science.gov (United States)

    Athokpam, Bijyalaxmi; Ramesh, Sai G.

    2018-04-01

    We present a study of the abstraction of alkyl hydrogen atoms from the β and α positions of ethanol by the CN radical in solution using the Empirical Valence Bond (EVB) method. We have built separate 2 × 2 EVB models for the Hβ and Hα reactions, where the atom transfer is parameterized using ab initio calculations. The intra- and intermolecular potentials of the reactant and product molecules were modelled with the General AMBER Force Field, with some modifications. We have carried out the dynamics in water and chloroform, which are solvents of contrasting polarity. We have computed the potential of mean force for both abstractions in each of the solvents. They are found to have a small and early barrier along the reaction coordinate with a large energy release. Analyzing the solvent structure around the reaction system, we have found two solvents to have little effect on either reaction. Simulating the dynamics from the transition state, we also study the fate of the energies in the HCN vibrational modes. The HCN molecule is born vibrationally hot in the CH stretch in both reactions and additionally in the HCN bends for the Hα abstraction reaction. In the early stage of the dynamics, we find that the CN stretch mode gains energy at the expense of the energy in CH stretch mode.

  19. 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...

  20. Efficient alpha-(alkylthio)alkyl-type radical formation in (*)OH-induced oxidation of alpha-(methylthio)acetamide.

    Science.gov (United States)

    Wisniowski, Pawel B; Hug, Gordon L; Pogocki, Dariusz; Bobrowski, Krzysztof

    2010-01-14

    Pulse radiolysis with UV-vis/ESR detection and steady-state gamma-radiolysis, combined with chromatographic techniques, were used to investigate the detailed mechanism of the (*)OH-induced oxidation of alpha-(methylthio)acetamide (alpha-MTA) in aqueous solution. The main pathway involves the formation of hydroxysulfuranyl radicals alpha-MTA-(>S(*)-OH) and alpha-(alkylthio)alkyl radicals H(3)C-S-(*)CH-C( horizontal lineO)-NH(2) (lambda(max) effect of both substituents in terms of the captodative effect. At low pH, alpha-MTA-(>S(*)-OH) radicals undergo efficient conversion to intermolecularly three-electron-bonded dimeric radical cations of alpha-MTA-(>S thereforeSS(*)-OH) radicals decompose via the elimination of water, formed through intramolecular hydrogen (attached to the nitrogen atom) transfer to the hydroxysulfuranyl moiety within a six-membered structure. This process leads to the formation of the imine radical H(3)C-S-CH(2)-C( horizontal lineO)(*)NH, which subsequently decays in three independent channels. The first decay channel begins with a beta-scission followed by hydrolysis and a subsequent Hofmann rearrangement. One of the end products of this first decay channel is CO(2), which was detected. The second decay channel involves an intramolecular hydrogen transfer from the deltaC carbon atom to the radical imine site producing the alpha-(alkylthio)alkyl radical H(2)C(*)-S-CH(2)-C( horizontal lineO)-NH(2). In the third decay channel there is a 1,3-hydrogen shift in the imine radical which forms the radical H(3)C-S-(*)CH-C( horizontal lineO)-NH(2). The presence of the amide group induces more complex radical chemistry that leads unexpectedly to the degradation of the CH(3)SCH(2)CONH(2) molecule into gaseous products, CO(2) and NH(3). These features of the mechanism of the (*)OH-induced oxidation of alpha-MTA are quite different from those seen in other organic sulfides in neutral solutions.

  1. Mechanism of carbon-halogen bond reductive cleavage in activated alkyl halide initiators relevant to living radical polymerization: theoretical and experimental study.

    Science.gov (United States)

    Isse, Abdirisak A; Gennaro, Armando; Lin, Ching Yeh; Hodgson, Jennifer L; Coote, Michelle L; Guliashvili, Tamaz

    2011-04-27

    The mechanism of reductive cleavage of model alkyl halides (methyl 2-bromoisobutyrate, methyl 2-bromopropionate, and 1-bromo-1-chloroethane), used as initiators in living radical polymerization (LRP), has been investigated in acetonitrile using both experimental and computational methods. Both theoretical and experimental investigations have revealed that dissociative electron transfer to these alkyl halides proceeds exclusively via a concerted rather than stepwise manner. The reductive cleavage of all three alkyl halides requires a substantial activation barrier stemming mainly from the breaking C-X bond. The activation step during single electron transfer LRP (SET-LRP) was originally proposed to proceed via formation and decomposition of RX(•-) through an outer sphere electron transfer (OSET) process (Guliashvili, T.; Percec, V. J. Polym. Sci., Part A: Polym. Chem. 2007, 45, 1607). These radical anion intermediates were proposed to decompose via heterolytic rather than homolytic C-X bond dissociation. Here it is presented that injection of one electron into RX produces only a weakly associated charge-induced donor-acceptor type radical anion complex without any significant covalent σ type bond character between carbon-centered radical and associated anion leaving group. Therefore, neither homolytic nor heterolytic bond dissociation applies to the reductive cleavage of C-X in these alkyl halides inasmuch as a true radical anion does not form in the process. In addition, the whole mechanism of SET-LRP has to be revisited since it is based on presumed OSET involving intermediate RX(•-), which is shown here to be nonexistent.

  2. Photodissociation dynamics of the simplest alkyl peroxy radicals, CH3OO and C2H5OO, at 248 nm

    Science.gov (United States)

    Sullivan, Erin N.; Nichols, Bethan; Neumark, Daniel M.

    2018-01-01

    The photodissociation dynamics of the simplest alkyl peroxy radicals, methyl peroxy (CH3OO) and ethyl peroxy (C2H5OO), are investigated using fast beam photofragment translational spectroscopy. A fast beam of CH3OO- or C2H5OO- anions is photodetached to generate neutral radicals that are subsequently dissociated using 248 nm photons. The coincident detection of the photofragment positions and arrival times allows for the determination of mass, translational energy, and angular distributions for both two-body and three-body dissociation events. CH3OO exhibits repulsive O loss resulting in the formation of O(1D) + CH3O with high translational energy release. Minor two-body channels leading to OH + CH2O and CH3O + O(3P) formation are also detected. In addition, small amounts of H + O(3P) + CH2O are observed and attributed to O loss followed by CH3O dissociation. C2H5OO exhibits more complex dissociation dynamics, in which O loss and OH loss occur in roughly equivalent amounts with O(1D) formed as the dominant O atom electronic state via dissociation on a repulsive surface. Minor two-body channels leading to the formation of O2 + C2H5 and HO2 + C2H4 are also observed and attributed to a ground state dissociation pathway following internal conversion. Additionally, C2H5OO dissociation yields a three-body product channel, CH3 + O(3P) + CH2O, for which the proposed mechanism is repulsive O loss followed by the dissociation of C2H5O over a barrier. These results are compared to a recent study of tert-butyl peroxy (t-BuOO) in which 248 nm excitation results in three-body dissociation and ground state two-body dissociation but no O(1D) production.

  3. Side chain variations radically alter the diffusion of poly(2-alkyl-2-oxazoline) functionalised nanoparticles through a mucosal barrier.

    Science.gov (United States)

    Mansfield, Edward D H; de la Rosa, Victor R; Kowalczyk, Radoslaw M; Grillo, Isabelle; Hoogenboom, Richard; Sillence, Katy; Hole, Patrick; Williams, Adrian C; Khutoryanskiy, Vitaliy V

    2016-08-16

    Functionalised nanomaterials are gaining popularity for use as drug delivery vehicles and, in particular, mucus penetrating nanoparticles may improve drug bioavailability via the oral route. To date, few polymers have been investigated for their muco-penetration, and the effects of systematic structural changes to polymer architectures on the penetration and diffusion of functionalised nanomaterials through mucosal tissue have not been reported. We investigated the influence of poly(2-oxazoline) alkyl side chain length on nanoparticle diffusion; poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline), and poly(2-n-propyl-2-oxazoline) were grafted onto the surface of thiolated silica nanoparticles and characterised by FT-IR, Raman and NMR spectroscopy, thermogravimetric analysis, and small angle neutron scattering. Diffusion coefficients were determined in water and in a mucin dispersion (using Nanoparticle Tracking Analysis), and penetration through a mucosal barrier was assessed using an ex vivo fluorescence technique. The addition of a single methylene group in the side chain significantly altered the penetration and diffusion of the materials in both mucin dispersions and mucosal tissue. Nanoparticles functionalised with poly(2-methyl-2-oxazoline) were significantly more diffusive than particles with poly(2-ethyl-2-oxazoline) while particles with poly(2-n-propyl-2-oxazoline) showed no significant increase compared to the unfunctionalised particles. These data show that variations in the polymer structure can radically alter their diffusive properties with clear implications for the future design of mucus penetrating systems.

  4. Oxidation of substituted alkyl radicals by IrCl62-, Fe(CN)63-, and MnO4- in aqueous solution. Electron transfer versus chlorine transfer from IrCl62-

    International Nuclear Information System (INIS)

    Steenken, S.; Neta, P.

    1982-01-01

    Alkyl radicals substituted at C/sub α/ by alkyl, carboxyl, hydroxyl, alkoxyl, and chlorine react in aqueous solutions with Ir/sup IV/Cl 6 2- to yield Ir(III) species. In the case of substitution by hydroxyl and alkoxyl, the rate constants are in the diffusion-controlled range ((4-6) x 10 9 M -1 s -1 ) and the reaction proceeds by electron transfer. In the case of ethyl, methyl, carboxymethyl, and chloromethyl radicals the rate constants range from 3.1 x 10 9 for ethyl to 2.8 x 10 7 M -1 s -1 for trichloromethyl and the reaction proceeds by chlorine transfer from IrCl 6 2- to the alkyl radical. With isopropyl and tert-butyll radicals the reaction proceeds by both electron and chlorine transfer. Alkyl radicals also react with Fe(CN) 6 3- . The rate constants increase strongly with increasing alkylation at C/sub α/ from 5 x 10 6 for methyl to 3.6 x 10 9 M -1 s -1 for tert-butyl, indicating that the transition state for the reaction is highly polar. Rate constants for reaction of MnO 4 - with alkyl radicals are of the order 10 9 M -1 s -1 . 4 figures, 1 table

  5. Theoretical investigation on the kinetics and mechanisms of hydroxyl radical-induced transformation of parabens and its consequences for toxicity: Influence of alkyl-chain length.

    Science.gov (United States)

    Gao, Yanpeng; Ji, Yuemeng; Li, Guiying; An, Taicheng

    2016-03-15

    As emerging organic contaminants (EOCs), the ubiquitous presence of preservative parabens in water causes a serious environmental concern. Hydroxyl radical ((•)OH) is a strong oxidant that can degrade EOCs through photochemistry in surface water environments as well as in advanced oxidation processes (AOPs). To better understand the degradation mechanisms, kinetics, and products toxicity of the preservative parabens in aquatic environments and AOPs, the (•)OH-initiated degradation reactions of the four parabens were investigated systematically using a computational approach. The four studied parabens with increase of alkyl-chain length were methylparaben (MPB), ethylparaben (EPB), propylparaben (PPB), and dibutylparaben (BPB). Results showed that the four parabens can be initially attacked by (•)OH through (•)OH-addition and H-abstraction routes. The (•)OH-addition route was more important for the degradation of shorter alkyl-chain parabens like MPB and EPB, while the H-abstraction route was predominant for the degradation of parabens with longer alkyl-chain for example PPB and BPB. In assessing the aquatic toxicity of parabens and their degradation products using the model calculations, the products of the (•)OH-addition route were found to be more toxic to green algae than original parabens. Although all degradation products were less toxic to daphnia and fish than corresponding parental parabens, they could be still harmful to these aquatic organisms. Furthermore, as alkyl-chain length increased, the ecotoxicity of parabens and their degradation products was found to be also increased. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Kinetics and mechanisms of the reactions of alkyl radicals with oxygen and with complexes of Co(III), Ru(III), and Ni(III)

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, D.

    1990-10-08

    The kinetics of the reactions of C{sub 2}H{sub 5} radical with Co(NH{sub 3}){sub 5}X{sup 2+}, Ru(NH{sub 3}){sub 5}X{sup 2+}, and Co(dmgH){sub 2} (X) (Y) (X = Br, Cl, N{sub 3}, SCN; Y = H{sub 2}O, CH{sub 3}CN) complexes were studied using laser flash photolysis of ethylcobalt complexes. The kinetics were obtained by the kinetic probe method. Some relative rate constants were also determined by a competition method based on ethyl halide product ratios. The kinetics of colligation reactions of a series of alkyl radicals with {beta}-Ni(cyclam){sup 2+} were studied using flaser flash photolysis of alkylcobalt complexes. Again, the kinetics were obtained by employing the kinetic probe competition method. The kinetics of the unimolecular homolysis of a series of RNi(cyclam)H{sub 2}O{sup 2+} were studied. Activation parameters were obtained for the unimolecular homolysis of C{sub 2}H{sub 5}Ni(cyclam)H{sub 2}O{sup 2+}. Kinetic and thermodynamic data obtained from these reactions were compared with those for the {sigma}-bonded organometallic complexes. The kinetics of the unimolecular homolysis of a series of RNi(cyclam)H{sub 2}O{sup 2+} complexes were studied by monitoring the formation of the oxygen insertion product RO{sub 2}Ni(cyclam)H{sub 2}O{sup 2+}. The higher rate constants for the reactions of alkyl radicals with oxygen in solution, as compared with those measured in the gas phase, were discussed. 30 refs.

  7. Strategy for O-Alkylation of Serine and Threonine from Serinyl and Threoninyl Acetic Acids by Photoinduced Decarboxylative Radical Reactions: Connection between Serine/Threonine and Carbohydrates/Amino Acids at the Side Chain.

    Science.gov (United States)

    Yamamoto, Takashi; Iwasaki, Tomoya; Morita, Toshio; Yoshimi, Yasuharu

    2018-04-06

    O-Alkylations of serine and threonine derivatives at the hydroxy group were achieved using photoinduced decarboxylative radical reactions of serinyl and threoninyl acetic acids with an organic photocatalyst without racemization under mild conditions. Photoinduced decarboxylative radical additions of serinyl and threoninyl acetic acids to electron-deficient alkenes provided linked serine and threonine with carbohydrates and amino acids at the side chain. In addition, O-methylations containing deuterium and O-benzylation of serine were performed under similar photochemical conditions.

  8. [The stability of the alkylating derivatives of oligodeoxyribonucleotides containing a cholesterol or phenazine radical added to the 3'-termination during their interaction with Acholeplasma laidlawii PG-8].

    Science.gov (United States)

    Panchenko, L P; Egorov, O V; Skripal', I G; Raĭt, A S; Ivanova, E M; Zarytova, V F; Vlasov, V V

    1991-01-01

    Stability of alkylating derivatives of decathymidylates protected on the 3'-terminal by cholesterol and phenazine residues has been studied in the process of their interaction with cells of Acholeplasma laidlawii PG-8. It is shown that the studied reagents are not split by nucleases of A. laidlawii PG-8 for the time necessary for alkylation of mycoplasma biopolymers.

  9. 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.

  10. Measurements of photo-oxidation products from the reaction of a series of alkyl-benzenes with hydroxyl radicals during EXACT using comprehensive gas chromatography

    Directory of Open Access Journals (Sweden)

    J. F. Hamilton

    2003-01-01

    Full Text Available Photo-oxidation products from the reaction of a series of alkyl-benzenes, (benzene, toluene, p-xylene and 1,3,5-trimethyl-benzene with hydroxyl radicals in the presence of NOx have been investigated using comprehensive gas chromatography (GCxGC. A GCxGC system has been developed which utilises valve modulation and independent separations as a function of both volatility and polarity. A number of carbonyl-type compounds were identified during a series of reactions carried out at the European Photoreactor (EUPHORE, a large volume outdoor reaction chamber in Valencia, Spain. Experiments were carried as part of the EXACT project (Effects of the oXidation of Aromatic Compounds in the Troposphere. Two litre chamber air samples were cryo-focused, with a sampling frequency of 30 minutes, allowing the evolution of species to be followed over oxidation periods of 3-6 hours. To facilitate product identification, several carbonyl compounds, which were possible products of the photo-oxidation, were synthesised and used as reference standards. For toluene reactions, observed oxygenated intermediates found included the co-eluting pair a-angelicalactone/4-oxo-2-pentenal, maleic anhydride, citraconic anhydride, benzaldehyde and p-methyl benzoquinone. In the p-xylene experiment, the products identified were E/Z-hex-3-en-2,5-dione and citraconic anhydride. For 1,3,5-TMB reactions, the products identified were 3,5-dimethylbenzaldehyde, 3,5-dimethyl-3H-furan-2-one and 3-methyl-5-methylene-5H-furan-2-one. Preliminary quantification was carried out on identified compounds using liquid standards. Comparison of FTIR and GCxGC for the measurement of the parent aromatics generally showed good agreement. Comparison of the concentrations observed by GCxGC to concentration-time profiles simulated using the Master Chemical Mechanism, MCMv3, demonstrates that this mechanism significantly over-predicts the concentrations of many product compounds and highlights the

  11. Measurements of photo-oxidation products from the reaction of a series of alkyl-benzenes with hydroxyl radicals during EXACT using comprehensive gas chromatography

    Science.gov (United States)

    Hamilton, J. F.; Lewis, A. C.; Bloss, C.; Wagner, V.; Henderson, A. P.; Golding, B. T.; Wirtz, K.; Martin-Reviejo, M.; Pilling, M. J.

    2003-11-01

    Photo-oxidation products from the reaction of a series of alkyl-benzenes, (benzene, toluene, p-xylene and 1,3,5-trimethyl-benzene) with hydroxyl radicals in the presence of NOx have been investigated using comprehensive gas chromatography (GCxGC). A GCxGC system has been developed which utilises valve modulation and independent separations as a function of both volatility and polarity. A number of carbonyl-type compounds were identified during a series of reactions carried out at the European Photoreactor (EUPHORE), a large volume outdoor reaction chamber in Valencia, Spain. Experiments were carried as part of the EXACT project (Effects of the oXidation of Aromatic Compounds in the Troposphere). Two litre chamber air samples were cryo-focused, with a sampling frequency of 30 minutes, allowing the evolution of species to be followed over oxidation periods of 3-6 hours. To facilitate product identification, several carbonyl compounds, which were possible products of the photo-oxidation, were synthesised and used as reference standards. For toluene reactions, observed oxygenated intermediates found included the co-eluting pair a-angelicalactone/4-oxo-2-pentenal, maleic anhydride, citraconic anhydride, benzaldehyde and p-methyl benzoquinone. In the p-xylene experiment, the products identified were E/Z-hex-3-en-2,5-dione and citraconic anhydride. For 1,3,5-TMB reactions, the products identified were 3,5-dimethylbenzaldehyde, 3,5-dimethyl-3H-furan-2-one and 3-methyl-5-methylene-5H-furan-2-one. Preliminary quantification was carried out on identified compounds using liquid standards. Comparison of FTIR and GCxGC for the measurement of the parent aromatics generally showed good agreement. Comparison of the concentrations observed by GCxGC to concentration-time profiles simulated using the Master Chemical Mechanism, MCMv3, demonstrates that this mechanism significantly over-predicts the concentrations of many product compounds and highlights the uncertainties which exist in

  12. 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)

  13. Multiphase chemistry of glyoxal: revised kinetics of the alkyl radical reaction with molecular oxygen and the reaction of glyoxal with OH, NO3, and SO4- in aqueous solution.

    Science.gov (United States)

    Schaefer, T; van Pinxteren, D; Herrmann, H

    2015-01-06

    The rate constant for the reaction of the hydrated glyoxyl radical (CH(OH)2-C(OH)2(·) with O2 has been determined as k(298) K = (1.2 ± 0.3) × 10(9) L mol(-1) s(-1) at pH 4.8. This experimental value is considerably higher than a widely used estimated value of about k = 1 × 10(6) L mol(-1) s(-1). As the aqueous phase conversion of glyoxal is of wide interest for aqSOA formation, we suggest that the newly determined rate constant should be applied in multiphase models. The formation of the dimerization product tartaric acid has as well been studied. This product is found, however in significant yields only when the oxygen content of the solution is reduced. The formation of dimers from the recombination of alkyl radicals in the atmospheric aqueous phase should hence be treated with great care. Finally, the reactions of the free radicals OH, NO3, and SO4(-) with glyoxal have been investigated and rate constants of k(298) K (OH) = (9.2 ± 0.5) × 10(8) L mol(-1) s(-1), k(298) K (SO4(-)) = (2.4 ± 0.2) × 10(7) L mol(-1) s(-1) and k(298) K (NO3) = (4.5 ± 0.3) × 10(6) L mol(-1) s(-1) were obtained.

  14. Infrared laser spectroscopy of the n-propyl and i-propyl radicals: Stretch-bend Fermi coupling in the alkyl CH stretch region

    Science.gov (United States)

    Franke, Peter R.; Tabor, Daniel P.; Moradi, Christopher P.; Douberly, Gary E.; Agarwal, Jay; Schaefer, Henry F.; Sibert, Edwin L.

    2016-12-01

    The n-propyl and i-propyl radicals were generated in the gas phase via pyrolysis of n-butyl nitrite [CH3(CH2)3ONO] and i-butyl nitrite [(CH3)2CHCH2ONO], respectively. Nascent radicals were promptly solvated by a beam of He nanodroplets, and the infrared spectra of the radicals were recorded in the CH stretching region. Several previously unreported bands are observed between 2800 and 3150 cm-1. The CH stretching modes observed above 3000 cm-1 are in excellent agreement with CCSD(T) anharmonic frequencies computed using second-order vibrational perturbation theory. However, between 2800 and 3000 cm-1, the spectra of n- and i-propyl radicals become congested and difficult to assign due to the presence of multiple anharmonic resonance polyads. To model the spectrally congested region, Fermi and Darling-Dennison resonances are treated explicitly using "dressed" Hamiltonians and CCSD(T) quartic force fields in the normal mode representation, and the agreement with experiment is less than satisfactory. Computations employing local mode effective Hamiltonians reveal the origin of the spectral congestion to be strong coupling between the high frequency CH stretching modes and the lower frequency CHn bending/scissoring motions. The most significant coupling is between stretches and bends localized on the same CH2/CH3 group. Spectral simulations using the local mode approach are in excellent agreement with experiment.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. The free radical species in polyacrylonitrile fibers induced by γ-radiation and their decay behaviors

    International Nuclear Information System (INIS)

    Liu Weihua; Wang Mouhua; Xing Zhe; Wu Guozhong

    2012-01-01

    Free radicals in vacuum, air and oxygen atmospheres were studied using electron spin resonance (ESR). Mainly two types of radicals, namely alkyl radicals and polyimine radicals, are formed in polyacrylonitrile (PAN) fibers after γ-ray irradiation. The G value of the radical formation was calculated to be 2.1 (number of radicals per 100 eV absorbed) in air at room temperature based on the ESR measurements. The radical stability and decay behaviors at room temperature and elevated temperatures were also investigated under different atmospheres. The alkyl radicals were found to be rather stable when stored in vacuum at room temperature, but they decayed via reaction with oxygen when stored in air. The alkyl radicals disappeared completely after a thermal treatment at 110 °C in vacuum, but only 15% of the polyimine radicals decayed; this indicates that polyimine radicals are more stable compared to the alkyl radicals due to their lower mobility. - Highlights: ► Radicals formed by radiation were assigned to polyimine and alkyl radicals. ► G-value of radicals was measured to be 2.1 per 100 eV. ► The radicals were found to be extremely stable in vacuum at room temperature. ► Effect of oxygen on radical decay under various conditions was studied.

  1. 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

  2. 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

  3. Experimental and theoretical studies of the reaction of the OH radical with alkyl sulfides: 3. Kinetics and mechanism of the OH initiated oxidation of dimethyl, dipropyl, and dibutyl sulfides: reactivity trends in the alkyl sulfides and development of a predictive expression for the reaction of OH with DMS.

    Science.gov (United States)

    Williams, M B; Campuzano-Jost, P; Hynes, A J; Pounds, A J

    2009-06-18

    A pulsed laser photolysis-pulsed laser-induced fluorescence technique has been employed to measure rate coefficients for the OH-initiated oxidation of dimethyl sulfide (DMS), its deuterated analog (DMS-d(6)), dipropyl sulfide (DPS), and dibutyl sulfide (DBS). Effective rate coefficients have been measured as a function of the partial pressure of O(2) over the temperature range of 240-295 K and at 200 and 600 Torr total pressure. We report the first observations of an O(2) enhancement in the effective rate coefficients for the reactions of OH with DPS and DBS. All observations are consistent with oxidation proceeding via a two-channel oxidation mechanism involving abstraction and addition channels. Structures and thermochemistry of the DPSOH and DBSOH adducts were calculated. Calculated bond strengths of adducts increase with alkyl substitution but are comparable to that of the DMSOH adduct and are consistent with experimental observations. Reactivity trends across the series of alkyl sulfide (C(2)-C(8)) reactions are analyzed. All reactions proceed via a two-channel mechanism involving either an H-atom abstraction or the formation of an OH adduct that can then react with O(2). Measurements presented in this work, in conjunction with previous measurements, have been used to develop a predictive expression for the OH-initiated oxidation of DMS. This expression is based on the elementary rate coefficients in the two-channel mechanism. The expression can calculate the effective rate coefficient for the reaction of OH with DMS over the range of 200-300 K, 0-760 Torr, and 0-100% partial pressure of O(2). This expression expands on previously published work but is applicable to DMS oxidation throughout the troposphere.

  4. 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.

  5. 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

  6. In situ EPR studies of reaction pathways in Titania photocatalyst-promoted alkylation of alkenes.

    Science.gov (United States)

    Rhydderch, Shona; Howe, Russell F

    2015-03-03

    In situ EPR spectroscopy at cryogenic temperatures has been used to observe and identify paramagnetic species produced when titania is irradiated in the presence of reactants used in the photocatalytic alkylation of maleimide with t-butyl carboxylic acid or phenoxyacetic acid. It is shown that maleimide acts as an acceptor of conduction band electrons. Valence band holes oxidise t-butyl carboxylic acid to the t-butyl radical and phenoxyacetic acid to the phenoxyacetic acid radical cation. In the presence of maleimide, the phenoxymethyl radical is formed from phenoxyacetic acid. The relevance of these observations to the mechanisms of titania photocatalyst-promoted alkylation of alkenes is discussed.

  7. Free radical-mediated hydroxymethylation using CO and HCHO.

    Science.gov (United States)

    Kawamoto, Takuji; Ryu, Ilhyong

    2012-01-01

    Tin-free radical hydroxymethylations of haloalkanes using CO and HCHO as a C1 unit proceed efficiently in the presence of borohydrides as radical mediators. In the approach using CO, the formation of aldehydes by radical carbonylation and their subsequent reduction by hydrides lead to alcohols. On the other hand, the use of formaldehyde is more straightforward, in which the key reaction is alkyl radical addition to formaldehyde to give alkoxy radical, which abstracts hydrogen from borohydride reagents. The cascade sequences were observed in the reaction of cholesteryl bromide with HCHO, which displays the diverse applications of HCHO in radical chemistry.

  8. 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)

  9. 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.

  10. 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...

  11. 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

  12. Radical intermediates involved in the bleaching of the carotenoid crocin. Hydroxyl radicals, superoxide anions and hydrated electrons

    International Nuclear Information System (INIS)

    Bors, W.; Saran, M.; Michel, C.

    1982-01-01

    The participation of the primary radicals in the bleaching of aqueous solutions of the carotenoid crocin by ionizing radiation was investigated, employing both X-radiolysis and pulse radiolysis. The pulse-radiolytic data demonstrated a very rapid diffusion-controlled attack by both hydroxyl radicals (radicalsOH) and hydrated electrons (e - sub(aq)), while superoxide anions (O 2 - ) did not react at all. The site of the initial reaction of these radicals was not limited to the polyene chromophore. Slower secondary reactions involving crocin alkyl or peroxy radicals contribute mainly to the overall bleaching, in particular during steady-state irradiation. (author)

  13. 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

  14. 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)

  15. Synthesis of tetrahydrokhusitone. Annulation of the cyclohexane ring by free radical and carbanionic sequence of reactions

    Directory of Open Access Journals (Sweden)

    ZIVORAD CEKOVIC

    2003-05-01

    Full Text Available The synthesis of norcadinane sesquiterpene tetrahydrokhusitone 1 has been achieved by a new method for annulation of cyclohexane ring involving a sequence of free radical d-alkylation of the non-activated carbon atom and intramolecular carbanionic alkylation. (–-Menthol was used as the starting compound.

  16. Electron spin resonance study of radicals in irradiated polyethylene

    International Nuclear Information System (INIS)

    Fujimura, Takashi

    1979-02-01

    In order to elucidate radiation effect in polyethylene, the nature and behavior of radicals produced in polyethylene and the model compound of polyethylene irradiated at 77 0 K were studied by using electron spin resonance. The structure of radical pairs, which are composed of two radicals produced very closely each other, was investigated in drawn polyethylene and the single crystal of n-eicosane. The radical pairs of intrachain type and interchain type were found in polyethylene and n-eicosane respectively. It was suggested that these two types of radical pairs are the precursors of double bonds and crosslinks respectively. The thermal decay reactions of radicals themselves produced in irradiated polyethylene were investigated. It was made clear that the short range distances between two radicals play an important role in the decay reaction of alkyl radicals at low temperatures. The trapping regions of radicals were studied and it was clarified that allyl radicals, which are produced by the reaction of alkyl radicals with double bonds, are trapped both in the crystalline and non-crystalline regions. (author)

  17. Efficiency of radical yield in alkylthymine and alkyluracil by high-LET irradiation

    International Nuclear Information System (INIS)

    Nakagawa, Seiko; Ohta, Nobuaki; Murakami, Takeshi

    2010-01-01

    Penthylthymines and hexyl-, nonyl-, and decyl- uracils were irradiated by C-ion (3.5 GeV) and γ-ray at 77 K. ESR spectra were measured to study radiation induced radicals in the temperature range from 108 to 273 K. A dihydro-5-yl (5-yl) radical formed by H addition to C6 carbon and a secondary alkyl radical by C-H bond fission at the second carbon from the end of the alkyl group were produced at 108 K. A dihydrouracil-6-yl (6-yl) radical formed by H addition to C5 carbon increased with increasing temperature for alkyluracils. The spectral feature obtained by C-ion irradiation was coincident with that by γ-irradiation. Total radical yields increased by alkylation and with increasing the length of alkyl chain. Yields of both 5-yl and secondary alkyl radicals irradiated by C-ion were less than those by γ-ray for penthylthymines and hexyluracil. On the contrary, radical yields were almost the same between ion and γ-ray irradiation for nonyl- and decyl-uracil. Mechanism of radical formation and effect of high-LET irradiation were discussed.

  18. The free radical process for the polymer surface treated by radio frequency plasma

    International Nuclear Information System (INIS)

    Ma Yuguang; Yang Meiling; Shen Jiacong; Zheng Yingguang

    1992-01-01

    The formation and translation of the free radicals on the polymer surface treated by plasmas were studied and observed by ESR measurement. The results show that C-C bond split was main reaction in the process of the polymer irradiated by plasma, by which a stable alkyl free radical was formed. When alkyl free radical contacted with air, they translate into peroxide radical instantaneously. The peroxide radical was not as stable as radical in vacuum, they can react each other to form some polar-groups on polymer surface. The interaction between the peroxide free radical and polymer chain was correlative not only to the structure of polymer but also to the molecular motion of the polymer chain. The nature of plasma treating polymer surface was that the peroxide radicals were led onto polymer surface

  19. Spin trapping study on the nature of radicals generated by X radiolysis and peroxidation of linolenic acid

    International Nuclear Information System (INIS)

    Azizova, O.A.; Osipov, A.N.; Zubarev, V.E.; Yakhyaev, A.V.; Vladimirov, Yu.A.; Savov, V.M.; Kagan, V.E.

    1983-01-01

    The radicals of linolenic acid and their spin adducts (SA) with PBN formed during X radiolysis of linolenic acid and in lipid peroxidation with ferrous ions were investigated and identified. It was found that in the absence of oxygen in pure linolenic acid at 77 K X irradiation produces alkyl and carboxyl radicals. In the presence of the spin trap alkyl radical spin adducts were formed. Irradiation of linolenic acid in the presence of oxygen at 77 K also resulted in the formation of alkyl radicals. These radicals were transformed into peroxy radicals in the interaction of alkyl radical with oxygen upon heating to 117 K. In the presence of spin trap X irradiation of linolenic acid and heating of the sample up to 300 K gave rise to EPR spectra of SA alkyl and unidentified radicals. Lipid peroxidation of linolenic acid induced by ferrous ions in the presence of spin trap also formed radicals and SA of linolenic acid. The spectral parameters of SA generated with ferrous ions in lipid peroxidation and of those generated during X radiolysis do not differ. The similarity of spectral parameters of SA in these two cases suggests a similarity in the structure of linolenic acid radicals. (author)

  20. 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

  1. 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.

  2. Indium-copper and indium-silver mediated barbier-grignard-type alkylation reaction of aldehydes using unactivated alkyl halides in water.

    Science.gov (United States)

    Shen, Zhi-Liang; Yeo, Yan-Lin; Loh, Teck-Peng

    2008-05-16

    An efficient method has been developed for the Barbier-Grignard-type alkylation reaction of aldehydes (including aliphatic version) using unactivated alkyl halides in water in the presence of an In/CuI/I(2) or In/AgI/I(2) system. The reactions proceeded more efficiently in water than in organic solvent. In, CuI or AgI, and I(2) were all essential for the efficient progress of the reactions. A radical-type reaction mechanism was studied and proposed by using 4-pentenal as substrate.

  3. Distribution coefficients of purine alkaloids in water-ammonium sulfate-alkyl acetate-dialkyl phthalate systems

    Science.gov (United States)

    Korenman, Ya. I.; Krivosheeva, O. A.; Mokshina, N. Ya.

    2012-12-01

    The distribution of purine alkaloids (caffeine, theobromine, theophylline) was studied in the systems: alkyl acetates-dialkyl phtalate-salting-out agent (ammonium sulfate). The quantitative characteristics of the extraction-distribution coefficients ( D) and the degree of extraction ( R, %) are calculated. The relationships between the distribution coefficients of alkaloids and the length of the hydrocarbon radical in the molecule of alkyl acetate (dialkyl phtalate) are determined. The possibility of predicting the distribution coefficients is demonstrated.

  4. Mechanism of the extraction of nitric acid and water by organic solutions of tertiary alkyl-amines

    International Nuclear Information System (INIS)

    Gourisse, D.

    1966-06-01

    The micellar aggregation of tri-alkyl-ammonium nitrates in low polarity organic solvents has been verified by viscosity, conductivity and sedimentation velocity measurements. The aggregation depends upon the polarity of solvent, the length of the alkyl radicals and the organic concentration of the various constituents (tri-alkyl-ammonium nitrate, tri-alkyl-amine, nitric acid, water). The amine salification law has been established and the excess nitric acid and water solubilities in the organic solutions have been measured. Nitric acid and water are slightly more soluble in micellar organic solutions than in molecular organic solutions. A description of excess nitric acid containing tri-alkyl-ammonium nitrate solutions is proposed. (author) [fr

  5. 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

  6. Radical Islam

    Science.gov (United States)

    2002-07-01

    Muslim insurgents have a real following in many countries. In Mao’s parlance, the radical Muslim insurgent is the fish swimming in the ocean of the...indigenous beliefs 5% Tanzania: mainland - Christian 45%, Muslim 35%, indigenous beliefs 20%; Zanzibar - more than 99% Muslim Zambia: Christian 50...leather, frozen fish and seafood Bosnia and Herzegovina NA Brunei: crude oil, natural gas, refined products Chad: cotton, cattle, textiles Cocos Islands

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. High yield silicon carbide from alkylated or arylated pre-ceramic polymer

    International Nuclear Information System (INIS)

    Baney, R.H.; Gaul, J.H.

    1982-01-01

    Alkylated or arylated methylpolysilanes which exhibit ease of handling and are used to obtain silicon carbide ceramic materials in high yields contain 0 to 60 mole percent (CH 3 ) 2 Si double bond units and 40 to 100 mole percent CH 3 Si triple bond units, wherein there is also bonded to the silicon atoms other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl. They may be prepared by reaction of a Grignard reagent RMgX, where X is halogen and R is Csub(1-4)-alkyl or phenyl, with a starting material which is a solid at 25 0 C, and is identical to the product except that the remaining bonds on the silicon atoms are attached to another silicon atom, or a chlorine or a bromine atom. Ceramics result from heating the polysilane products to 1200 0 C, optionally with fillers. (author)

  14. 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.

  15. 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.

  16. Regioselectivity in Reactions between Bis(2-benzothiazolyl)ketone and Vinyl Grignard Reagents: C- versus O-alkylation-Part III.

    Science.gov (United States)

    Boga, Carla; Bordoni, Silvia; Casarin, Lucia; Micheletti, Gabriele; Monari, Magda

    2018-01-15

    The reaction between bis(2-benzothiazolyl)ketone and vinyl Grignard reagents bearing different substituents on the vinyl moiety gave the product derived from attack on the carbonylic carbon- and/or oxygen-atom. The regioselectivity of the attack depends on the kind of substituents bound to the vinylic carbon atoms and on their relative position. The reaction between vinylmagnesium bromide and 2-methyl-1-propenylmagnesium bromide was carried out under different experimental conditions and in the presence of radical scavengers. The results indicate a plausible mechanistic pathway involving radical intermediates in the case of O -alkylation, but a polar ones in the case of classic C -alkylation. This agrees with our previous reports indicating a key role played by the delocalization ability of the substituents bound to the carbonyl group in driving the regioselectivity of the vinylmagnesium bromide attack towards O -alkylation. Further support of this was obtained by diffractometric analysis of four distinct bis(heteroaryl)ketones.

  17. Photoionization of N-Alkyl N, N', - in Organized Molecular Assemblies

    Science.gov (United States)

    Stenland, Christopher John

    The electron donors N-Alkyl N,N^ ',N^' -trimethylbenzidines (C_{rm n }TMB with n = 1 to 16) were synthesized then photoionized in rapidly frozen micellar, vesicular and reversed micellar solutions. The N-alkyl functionalization of these electron donors alters the solubilization location of C_{rm n}TMB with respect to the aqueous interface in these organized molecular assemblies. The alteration of the solubilization location affects the, relative photoyield. Electron spin resonance is used to quantify and identify the photoproduced radicals in these rapidly frozen solution. Electron spin echo modulation spectroscopy is used to monitor the distance of the cation radical of C_{rm n}TMB to the deuterated aqueous interface. In micelles, longer N-alkyl chains on C _{rm n}TMB push the benzidine moiety towards the aqueous interface. However the photoyield remains constant versus the C_{rm n}TMB alkyl chain length. The lack of a photoyield trend is interpreted in terms of the solubilization geometry which determines the paths of electron escape to form charge separated products. In vesicles, the longer the alkyl chain on C _{rm n}TMB, the deeper the benzidine moiety is located, and the lower the photoyield. The relative photoyield in bilayer vesicles depends on the proximity of the electron donor to the interface. In Aerosol dioctyl reversed micelles in isooctane, a negligible C_{rm n}TMB alkyl chain length effect is observed. Instead the water pool size, which can be manipulated by altering the mole ratio of water to surfactant, is the dominant factor which controls the net photoyield.

  18. Enhanced Synthesis of Alkyl Amino Acids in Miller's 1958 H2S Experiment

    Science.gov (United States)

    Parker, Eric T.; Cleaves, H. James; Callahan, Michael P.; Dworkin, James P.; Glavin, Daniel P.; Lazcano, Antonio; Bada, Jeffrey L.

    2011-01-01

    Stanley Miller's 1958 H2S-containing experiment, which included a simulated prebiotic atmosphere of methane (CH4), ammonia (NH3), carbon dioxide (CO2), and hydrogen sulfide (H2S) produced several alkyl amino acids, including the alpha-, beta-, and gamma-isomers of aminobutyric acid (ABA) in greater relative yields than had previously been reported from his spark discharge experiments. In the presence of H2S, aspariic and glutamic acids could yield alkyl amino acids via the formation of thioimide intermediates. Radical chemistry initiated by passing H2S through a spark discharge could have also enhanced alkyl amino acid synthesis by generating alkyl radicals that can help form the aldehyde and ketone precursors to these amino acids. We propose mechanisms that may have influenced the synthesis of certain amino acids in localized environments rich in H2S and lightning discharges, similar to conditions near volcanic systems on the early Earth, thus contributing to the prebiotic chemical inventory of the primordial Earth.

  19. 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...

  20. Catalytic alkylation of remote C-H bonds enabled by proton-coupled electron transfer.

    Science.gov (United States)

    Choi, Gilbert J; Zhu, Qilei; Miller, David C; Gu, Carol J; Knowles, Robert R

    2016-11-10

    Despite advances in hydrogen atom transfer (HAT) catalysis, there are currently no molecular HAT catalysts that are capable of homolysing the strong nitrogen-hydrogen (N-H) bonds of N-alkyl amides. The motivation to develop amide homolysis protocols stems from the utility of the resultant amidyl radicals, which are involved in various synthetically useful transformations, including olefin amination and directed carbon-hydrogen (C-H) bond functionalization. In the latter process-a subset of the classical Hofmann-Löffler-Freytag reaction-amidyl radicals remove hydrogen atoms from unactivated aliphatic C-H bonds. Although powerful, these transformations typically require oxidative N-prefunctionalization of the amide starting materials to achieve efficient amidyl generation. Moreover, because these N-activating groups are often incorporated into the final products, these methods are generally not amenable to the direct construction of carbon-carbon (C-C) bonds. Here we report an approach that overcomes these limitations by homolysing the N-H bonds of N-alkyl amides via proton-coupled electron transfer. In this protocol, an excited-state iridium photocatalyst and a weak phosphate base cooperatively serve to remove both a proton and an electron from an amide substrate in a concerted elementary step. The resultant amidyl radical intermediates are shown to promote subsequent C-H abstraction and radical alkylation steps. This C-H alkylation represents a catalytic variant of the Hofmann-Löffler-Freytag reaction, using simple, unfunctionalized amides to direct the formation of new C-C bonds. Given the prevalence of amides in pharmaceuticals and natural products, we anticipate that this method will simplify the synthesis and structural elaboration of amine-containing targets. Moreover, this study demonstrates that concerted proton-coupled electron transfer can enable homolytic activation of common organic functional groups that are energetically inaccessible using

  1. 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.

  2. 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.

  3. 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.

  4. Some features of formation and dissolution of a series of Pu(IV) and Zr alkyl and butyl alkyl phosphates in the system TBP -n-dodecane - nitric acid - water

    International Nuclear Information System (INIS)

    Markov, G.S.; Moshkov, M.M.; Kokina, S.A.

    1990-01-01

    The formation and composition of salts produced on interaction of a series of alkyl- and butylalkylphosphoric acids having alkyl radical chain lengths from C 4 to C 1 0 with Pu(IV) and Zr in organic and aqueous phases of the system TBP - n-dodecane -nitric acid - water were studied. The composition of compounds was found to depend on the conditions of their formation, defined first of all by the HNO 3 concentration in aqueous and organic phases. (author) 12 refs.; 4 figs.; 1 tab

  5. New insight into the spatiotemporal variability and source apportionments of C1-C4 alkyl nitrates in Hong Kong

    Science.gov (United States)

    Ling, Zhenhao; Guo, Hai; Simpson, Isobel Jane; Saunders, Sandra Maria; Lam, Sean Ho Man; Lyu, Xiaopu; Blake, Donald Ray

    2016-07-01

    C1-C4 alkyl nitrates (RONO2) were measured concurrently at a mountain site, Tai Mo Shan (TMS), and an urban site, Tsuen Wan (TW), at the base of the same mountain in Hong Kong from September to November 2010. Although the levels of parent hydrocarbons were much lower at TMS (p TMS mainly resulted from the photooxidation of the parent hydrocarbons at TW during mesoscale circulation, i.e., valley breezes, corresponding to 52-86 % of the alkyl nitrate levels at TMS. Furthermore, regional transport from the inland PRD region made significant contributions to the levels of alkyl nitrates (˜ 58-82 %) at TMS in the non-meso scenario, resulting in similar levels of alkyl nitrates observed at the two sites. The simulation of secondary formation pathways using a photochemical box model found that the reaction of alkyl peroxy radicals (RO2) with nitric oxide (NO) dominated the formation of RONO2 at both sites, and the formation of alkyl nitrates contributed negatively to O3 production, with average reduction rates of 4.1 and 4.7 pptv pptv-1 at TMS and TW, respectively.

  6. 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.

  7. 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.

  8. A radical approach to radical innovation

    NARCIS (Netherlands)

    D. Deichmann (Dirk); J.C.M. van den Ende (Jan)

    2014-01-01

    textabstractInnovation pays. Amazon, Apple, Facebook, Google – nearly every one of today’s most successful companies has a talent for developing radical new ideas. But how best to encourage radical initiative taking from employees, and does their previous success or failure at it play a role?

  9. Triethylborane-induced radical reactions with gallium hydride reagent HGaCl2.

    Science.gov (United States)

    Mikami, S; Fujita, K; Nakamura, T; Yorimitsu, H; Shinokubo, H; Matsubara, S; Oshima, K

    2001-06-14

    [see reaction]. A gallium hydride reagent, HGaCl2, was found to act as a radical mediator, like tributyltin hydride. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source.

  10. 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.

  11. 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

  12. Contemporary Radical Economics.

    Science.gov (United States)

    Sherman, Howard J.

    1984-01-01

    The origins of contemporary radical economics are examined. Applications of radical economics to price and value theory, labor segmentation theory, business cycles, industrial organization, government and business, imperialism and development, and comparative systems are reviewed. (Author/RM)

  13. 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.

  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. Suppression of superoxide anion generation catalyzed by xanthine oxidase with alkyl caffeates and the scavenging activity.

    Science.gov (United States)

    Masuoka, Noriyoshi; Kubo, Isao

    2016-01-01

    Alkyl caffeates are strong antioxidants and inhibitors of xanthine oxidase. However, it is unclear about the effect of caffeic acid and alkyl caffeates on superoxide anion (O2(-)) generation catalyzed by xanthine oxidase. Effects of caffeic acid and alkyl caffeates on the uric acid formation and O2(-) generation catalyzed by xanthine oxidase were analyzed. The scavenging activities of 1,1-diphenyl-2-picryhydrazyl (DPPH) radical and O2(-) generated with phenazine methosulfate (PMS) and NADH were examined. Caffeic acid derivatives equally suppressed O2(-) generation, and the suppression is stronger than inhibition of xanthine oxidase. Scavenging activity of O2(-) is low compared to the suppression of O2(-) generation. Suppression of O2(-) generation catalyzed by xanthine oxidase with caffeic acid derivatives was not due to enzyme inhibition or O2(-) scavenging but due to the reduction of xanthine oxidase molecules. Alkyl caffeates are effective inhibitors of uric acid and O2(-) catalyzed by xanthine oxidase as well as antioxidants for edible oil.

  16. 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.

  17. 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.

  18. 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.

  19. Radical theory of rings

    CERN Document Server

    Gardner, JW

    2003-01-01

    Radical Theory of Rings distills the most noteworthy present-day theoretical topics, gives a unified account of the classical structure theorems for rings, and deepens understanding of key aspects of ring theory via ring and radical constructions. Assimilating radical theory's evolution in the decades since the last major work on rings and radicals was published, the authors deal with some distinctive features of the radical theory of nonassociative rings, associative rings with involution, and near-rings. Written in clear algebraic terms by globally acknowledged authorities, the presentation

  20. 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

  1. 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.

  2. [Lavoisier and radicals].

    Science.gov (United States)

    Lafont, Olivier

    2007-01-01

    Lavoisier and his co-workers (Guyton de Morveau, Bertholet, Fourcroy) considered that acids were constituted of oxygen and of something else that they called radicals. These radicals were known in some cases, i.e. nitrogen for nitrous acid, carbon for carbonic acid, phosphorus for phosphoric acid. In the case of sulfur, the sulfuric radical could be associated with different quantities of oxigen leading to sulfuric or sulfurous acids. In other cases radicals remained unknown at the time i.e. muriatic radical for muriatic acid, or benzoyl radical for benzoic acid. It is interesting to notice that Lavoisier evoked the case of compound radicals constituted of different substances such as carbon and hydrogen.

  3. Dissociation or cyclization: options for a triad of radicals released from oxime carbamates.

    Science.gov (United States)

    McBurney, Roy T; Walton, John C

    2013-05-15

    A set of oxime carbamates having N-alkyl and N,N-dialkyl substituents were prepared via carbonyldiimidazole intermediates. It was shown by EPR spectroscopy that they underwent clean homolysis of their N-O bonds upon UV photolysis. During photolysis of acetophenone O-allylcarbamoyl oxime, the corresponding oxazolidin-2-onylmethyl radical was detected by EPR spectroscopy, providing the first evidence that N-monosubstituted carbamoyloxyl radicals can hold their structural integrity. N,N-Disubstituted carbamoyloxyl radicals dissociated rapidly at the lowest accessible temperatures. Above room temperature, both types of oxime carbamate acted as selective new precursors for aminyl and iminyl radicals. Rate parameters were measured for 5-exo cyclization of N-benzyl-N-pent-4-enylaminyl radicals; the rate constant was smaller than for C-centered and O-centered analogues. Oxime carbamates derived from the volatile diethylamine afforded aryliminyl radicals that proved convenient for phenanthridine preparations.

  4. 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.

  5. Contemporary Radical Prostatectomy

    Directory of Open Access Journals (Sweden)

    Qiang Fu

    2011-01-01

    Full Text Available Purpose. Patients diagnosed with clinically localized prostate cancer have more surgical treatment options than in the past. This paper focuses on the procedures' oncological or functional outcomes and perioperative morbidities of radical retropubic prostatectomy, radical perineal prostatectomy, and robotic-assisted laparoscopic radical prostatectomy. Materials and Methods. A MEDLINE/PubMed search of the literature on radical prostatectomy and other new management options was performed. Results. Compared to the open procedures, robotic-assisted radical prostatectomy has no confirmed significant difference in most literatures besides less blood loss and blood transfusion. Nerve sparing is a safe means of preserving potency on well-selected patients undergoing radical prostatectomy. Positive surgical margin rates of radical prostatectomy affect the recurrence and survival of prostate cancer. The urinary and sexual function outcomes have been vastly improved. Neoadjuvant treatment only affects the rate of positive surgical margin. Adjuvant therapy can delay and reduce the risk of recurrence and improve the survival of the high risk prostate cancer. Conclusions. For the majority of patients with organ-confined prostate cancer, radical prostatectomy remains a most effective approach. Radical perineal prostatectomy remains a viable approach for patients with morbid obesity, prior pelvic surgery, or prior pelvic radiation. Robot-assisted laparoscopic prostatectomy (RALP has become popular among surgeons but has not yet become the firmly established standard of care. Long-term data have confirmed the efficacy of radical retropubic prostatectomy with disease control rates and cancer-specific survival rates.

  6. 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.

  7. 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.

  8. Synthesis of 5-alkyl-3,4-difluorofuran-2(5H)-ones by lactonisation. Effects of substituents on cyclisation ability of fluorinated 4-hydroxyalkanoates. DFT calculations of the cyclisation energies

    Czech Academy of Sciences Publication Activity Database

    Hajduch, Jan; Duda, Z.; Beran, J.; Kvíčala, J.; Paleta, O.

    2014-01-01

    Roč. 162, Jun (2014), s. 45-59 ISSN 0022-1139 Institutional support: RVO:61388963 Keywords : methyl 2,3,3-trifluoroacrylate * regioselective radical addition * photo-induced addition * dehydrofluorination * 5-alkyl-3,4-difluorofuran-2(5H)-ones * 5-alkyl-3-fluorofuran-2(5H)-ones * exo-trig lactonisations * DFT lactonisation energy Subject RIV: CC - Organic Chemistry Impact factor: 1.948, year: 2014

  9. Inhibition and Promotion of Pyrolysis by Hydrogen Sulfide (H2S) and Sulfanyl Radical (SH)

    DEFF Research Database (Denmark)

    Zeng, Zhe; Altarawneh, Mohammednoor; Oluwoye, Ibukun

    2016-01-01

    the weakest C–H sites in alkenes and alkynes, except for ethylene, appears noticeably exothermic. Furthermore, abstraction of H from propene, 1-butene, and iso-butene displays pronounced spontaneity (i.e., ΔrG° hydrogen bond. However......, an alkyl radical readily abstracts H atom from H2S, with H2S acting as a potent scavenger for alkyl radicals in combustion processes. That is, these reactions proceed in the opposite direction than those involving SH and alkene or alkyne species, exhibiting shallow barriers and strong spontaneity. Our...... findings demonstrate that the documented inhibition effect of hydrogen sulfide (H2S) on pyrolysis of alkanes does not apply to alkenes and alkynes. During interaction with hydrocarbons, the inhibitive effect of H2S and promoting interaction of SH radical depend on the reversibility of the H abstraction...

  10. Fast Halogen Abstractions from Alkyl Halides by Alkyl Radicals. Quantitation of the Processes Occurring in and a Caveat for Studies Employing Alkyl Halide Mechanistic Probes.

    Science.gov (United States)

    1986-09-15

    Lepley, A. R.; Landau, R. L. J. Am. Chem. Soc. 1969, 92, 748-749. 7. Castelhano, A. L.; M’arriott, P. a.; Griller , D. J. Am. Chem. Soc. 1981, 103, 4262...Engel, P. S.; Gilbert, B. C.; Griller , D. J. Am. Chem. Soc. 1985, 107, 4721-4724. 20 •11. Johnston, L. J. ; Lusztyk, J.; Wayner, D. D. ’I

  11. 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.

  12. 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

  13. 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...

  14. 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)

  15. Effects of Molecular Iodine and 4-tert-Butylcatechol Radical Inhibitor on the Radical Polymerization of Styrene

    Directory of Open Access Journals (Sweden)

    Mojtaba Bozorg

    2017-05-01

    Full Text Available The presence of molecular iodine was studied in relation the molecular weight and molecular weight distribution of polystyrene, produced by radical poly merization. Radical polymerization of styrene initiated by 2,2׳-azobisisobutyronitrile (AIBN was performed at 70°C in the presence of molecular iodine. The synthesized polymers were characterized by gel permeation chromatography (GPC and proton- nuclear magnetic resonance (1H NMR techniques. The results of these reactions including conversion data, number-average molecular weight and molecular weight distribution were compared with those obtained for styrene radical polymerization initiated by AIBN at the same temperature in the absence of molecular iodine. It was found that the presence of iodine had a profound effect on the molecular weight and its distribution in the produced polystyrene. This was attributed to the ability of iodine to control the polymerization of styrene initiated by AIBN via reverse iodine transfer polymerization (RITP mechanism. The polymer produced by this method had a molecular weight of 10600 g/mol with a molecular weight polydispersity index of 1.3. Due to the importance of induction period in reverse iodine transfer radical polymerization, increasing the temperature to 120°C during the induction period resulted in shorter induction periods and the produced species led to better control of the molecular weight. Also, due to the role of iodine molecules as a radical inhibitor, the presence of a secondary radical inhibitor, i.e. 4-tert-butylcatechol, along with the iodine was investigated in radical polymerization of polystyrene initiated by AIBN. It was observed that the secondary radical inhibitor prevented the consumption of the iodine molecules by the radicals produced from decomposition of the AIBN initiator; therefore, alkyl halides were not produced during the induction period.

  16. The Preparation and Intramolecular Radical Cyclisation Reactions of Chiral Oxime Ethers

    Directory of Open Access Journals (Sweden)

    Booth Susan E.

    1998-01-01

    Full Text Available Chiral oxime ether 2 and Oxime ester 4 have been prepared by alkylation and esterification of the oxime 1. Racemic hydroxylamine 6 and chiral hydroxylamine 10 have been synthesised from N-hydroxysuccinimide and the corresponding alcohol in the presence of diethylazodicarboxylate, the two products were converted into the oxime ethers 7 and 11 respectively. The intramolecular radical cyclisation reactions of these oxime ethers and esters has been studied, successful reaction was observed to produce alkyl hydroxylamines 3, 8 and 12.

  17. Orgasm after radical prostatectomy

    NARCIS (Netherlands)

    Koeman, M; VanDriel, MF; Schultz, WCMW; Mensink, HJA

    Objective To evaluate the ability to obtain and the quality of orgasm after radical prostatectomy, Patients and methods The orgasms experienced after undergoing radical prostatectomy were evaluated in 20 men (median age 65 years, range 56-76) using a semi-structured interview and a self-administered

  18. Muonium and muonic radicals

    International Nuclear Information System (INIS)

    Burkhard, P.; Fischer, H.; Roduner, E.; Strub, W.; Geeson, D.; Symons, M.C.R.

    1985-01-01

    An energetic positive muon which is injected in a liquid sample of substrate molecules (S) creates an ionization track consisting of substrate cations (S + ) and electrons. Near the end of this track the muon may combine with an electron to form muonium (Mu) which is observable in inert liquids, but which reacts by addition to form a radical. Alternatively, the electron can add to S to form S - , which then combines with the muon to form the radical. Furthermore, instead of ending up in Mu or in a radical the muon may stay in a diamagnetic environment as a solvated muon, or as a muon substituting a proton in a molecule. Of interest in these schemes are the mechanisms and rates of formation of muonated radicals and in particular the rate constants for their reactions to products. Investigations are based on the observation of Mu and the radical by means of the μSR technique in transverse magnetic fields. (Auth.)

  19. 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...

  20. 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...

  1. 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...

  2. 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,...

  3. 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.

  4. 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)

  5. 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.

  6. 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 ...

  7. 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

  8. 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...

  9. 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 ...

  10. 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.

  11. 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.

  12. 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.)

  13. 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.

  14. Salvage robotic radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Samuel D Kaffenberger

    2014-01-01

    Full Text Available Failure of non-surgical primary treatment for localized prostate cancer is a common occurrence, with rates of disease recurrence ranging from 20% to 60%. In a large proportion of patients, disease recurrence is clinically localized and therefore potentially curable. Unfortunately, due to the complex and potentially morbid nature of salvage treatment, radical salvage surgery is uncommonly performed. In an attempt to decrease the morbidity of salvage therapy without sacrificing oncologic efficacy, a number of experienced centers have utilized robotic assistance to perform minimally invasive salvage radical prostatectomy. Herein, we critically evaluate the existing literature on salvage robotic radical prostatectomy with a focus on patient selection, perioperative complications and functional and early oncologic outcomes. These results are compared with contemporary and historical open salvage radical prostatectomy series and supplemented with insights we have gained from our experience with salvage robotic radical prostatectomy. The body of evidence by which conclusions regarding the efficacy and safety of robotic salvage radical prostatectomy can be drawn comprises fewer than 200 patients with limited follow-up. Preliminary results are promising and some outcomes have been favorable when compared with contemporary open salvage prostatectomy series. Advantages of the robotic platform in the performance of salvage radical prostatectomy include decreased blood loss, short length of stay and improved visualization. Greater experience is required to confirm the long-term oncologic efficacy and functional outcomes as well as the generalizability of results achieved at experienced centers.

  15. 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.

  16. Ascorbic Acid-Initiated Tandem Radical Cyclization of N-Arylacrylamides to Give 3,3-Disubstituted Oxindoles

    Directory of Open Access Journals (Sweden)

    Sheng Liu

    2015-08-01

    Full Text Available An ascorbic acid-promoted and metal-free tandem room temperature cyclization of N-arylacrylamides with 4-nitrobenzenediazonium generated in situ was developed. This reaction proceeds smoothly through a radical mechanism and provides an environmentally friendly alternative approach to biologically active 3-alkyl-3-benzyloxindoles, avoiding the use of excess oxidants and light irradiation.

  17. Radical's view of sciences

    International Nuclear Information System (INIS)

    Mittal, J.P.

    2004-01-01

    Full text: General concept in radiation biology is that free radicals are highly reactive and they can damage vital cellular molecules leading to injurious effects. However, in this talk, evidence will be presented through the techniques of electron paramagnetic resonance ( EPR ) and pulse radiolysis that free radicals can be highly selective in their reaction with the target molecules. In addition, attempts will be made to present a brief account of emerging scenario of free radical generation, identification and their involvement in radiation damage mechanisms in chemical and biological systems

  18. Diphenylphosphino Styrene-Containing Homopolymers: Influence of Alkylation and Mobile Anions on Physical Properties.

    Science.gov (United States)

    Jangu, Chainika; Schultz, Alison R; Wall, Candace E; Esker, Alan R; Long, Timothy E

    2016-07-01

    Conventional free radical polymerization and post-alkylation of 4-diphenylphosphino styrene (DPPS) generate a new class of high-molecular-weight phosphonium-containing homopolymers with tunable thermal, viscoelastic, and wetting properties. Post-alkylation and subsequent anion exchange provide an effective method for tuning Tg values and thermal stability as a function of alkyl chain length and counteranion selection (X(-) , BF4 (-) , TfO(-) , and Tf2 N(-) ). Rheological characterization facilitates the generation of time-temperature-superposition (TTS) pseudomaster curves and subsequent analysis of frequency sweeps at various temperatures reveals two relaxation modes corresponding to long-range segmental motion and the onset of viscous flow. Contact angle measurements reveal the influence of counteranion selection on wetting properties, revealing increased contact angles for homopolymers containing nucleophilic counteranions. These investigations provide fundamental insight into phosphonium-containing polymers, aiming to guide future research and applications involving electro-active polymeric devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Homegrown religious radicalization

    DEFF Research Database (Denmark)

    Khawaja, Iram

    It has been reported that a growing number of youngsters from Western Europe are engaging in conflicts motivated by religious and political conflicts in the Middle East. This paper explores the reasons behind this seemingly religious radicalization from the point of view of the youngsters...... and their families. Existing literature and ways of defining the social psychological process of radicalization will be discussed, and a theoretical framework based on a focus on (non-)belonging, Otherness and sense of community will be proposed. The framework will be utilized in an analysis of narratives from...... youngsters and parents of youngsters who have chosen a radicalized path in life. The paper will shed light on how the sense of and yearning for belonging and recognition have to be taken into account in our understanding of homegrown religious radicalization...

  20. Radical prostatectomy - discharge

    Science.gov (United States)

    ... to 6 months. You will learn exercises (called Kegel exercises) that strengthen the muscles in your pelvis. ... Radical prostatectomy Retrograde ejaculation Urinary incontinence Patient Instructions Kegel exercises - self-care Suprapubic catheter care Urinary catheters - ...

  1. Moderate and Radical Islam

    National Research Council Canada - National Science Library

    Rabasa, Angel

    2005-01-01

    This report presents the statement of Angel Rabasa, PhD, Senior Policy Analyst, The RAND Corporation, to the Committee on Armed Services, Defense Review Terrorism and Radical Islam Gap Panel, United...

  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. Free Radical Reactions in Food.

    Science.gov (United States)

    Taub, Irwin A.

    1984-01-01

    Discusses reactions of free radicals that determine the chemistry of many fresh, processed, and stored foods. Focuses on reactions involving ascorbic acid, myoglobin, and palmitate radicals as representative radicals derived from a vitamin, metallo-protein, and saturated lipid. Basic concepts related to free radical structure, formation, and…

  5. 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...

  6. 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.

  7. New insight into the spatiotemporal variability and source apportionments of C1–C4 alkyl nitrates in Hong Kong

    Directory of Open Access Journals (Sweden)

    Z. Ling

    2016-07-01

    Full Text Available C1–C4 alkyl nitrates (RONO2 were measured concurrently at a mountain site, Tai Mo Shan (TMS, and an urban site, Tsuen Wan (TW, at the base of the same mountain in Hong Kong from September to November 2010. Although the levels of parent hydrocarbons were much lower at TMS (p  <  0.05, similar alkyl nitrate levels were found at both sites regardless of the elevation difference, suggesting various source contributions of alkyl nitrates at the two sites. Prior to using a positive matrix factorization (PMF model, the data at TW were divided into "meso" and "non-meso" scenarios for the investigation of source apportionments with the influence of mesoscale circulation and regional transport, respectively. Secondary formation was the prominent contributor of alkyl nitrates in the meso scenario (60 ± 2 %, 60.2 ± 1.2 pptv, followed by biomass burning and oceanic emissions, while biomass burning and secondary formation made comparable contributions to alkyl nitrates in the non-meso scenario, highlighting the strong emissions of biomass burning in the inland Pearl River delta (PRD region. In contrast to TW, the alkyl nitrate levels measured at TMS mainly resulted from the photooxidation of the parent hydrocarbons at TW during mesoscale circulation, i.e., valley breezes, corresponding to 52–86 % of the alkyl nitrate levels at TMS. Furthermore, regional transport from the inland PRD region made significant contributions to the levels of alkyl nitrates (∼  58–82 % at TMS in the non-meso scenario, resulting in similar levels of alkyl nitrates observed at the two sites. The simulation of secondary formation pathways using a photochemical box model found that the reaction of alkyl peroxy radicals (RO2 with nitric oxide (NO dominated the formation of RONO2 at both sites, and the formation of alkyl nitrates contributed negatively to O3 production, with average reduction rates of 4.1 and 4.7 pptv pptv−1 at TMS and TW

  8. Laparoscopic radical trachelectomy.

    Science.gov (United States)

    Rendón, Gabriel J; Ramirez, Pedro T; Frumovitz, Michael; Schmeler, Kathleen M; Pareja, Rene

    2012-01-01

    The standard treatment for patients with early-stage cervical cancer has been radical hysterectomy. However, for women interested in future fertility, radical trachelectomy is now considered a safe and feasible option. The use of minimally invasive surgical techniques to perform this procedure has recently been reported. We report the first case of a laparoscopic radical trachelectomy performed in a developing country. The patient is a nulligravid, 30-y-old female with stage IB1 adenocarcinoma of the cervix who desired future fertility. She underwent a laparoscopic radical trachelectomy and bilateral pelvic lymph node dissection. The operative time was 340 min, and the estimated blood loss was 100mL. There were no intraoperative or postoperative complications. The final pathology showed no evidence of residual disease, and all pelvic lymph nodes were negative. At 20 mo of follow-up, the patient is having regular menses but has not yet attempted to become pregnant. There is no evidence of recurrence. Laparoscopic radical trachelectomy with pelvic lymphadenectomy in a young woman who desires future fertility may also be an alternative technique in the treatment of early cervical cancer in developing countries.

  9. Radical zinc-atom-transfer-based carbozincation of haloalkynes with dialkylzincs

    Directory of Open Access Journals (Sweden)

    Fabrice Chemla

    2013-02-01

    Full Text Available The formation of alkylidenezinc carbenoids by 1,4-addition/carbozincation of dialkylzincs or alkyl iodides based on zinc atom radical transfer, in the presence of dimethylzinc with β-(propargyloxyenoates having pendant iodo- and bromoalkynes, is disclosed. Formation of the carbenoid intermediate is fully stereoselective at −30 °C and arises from a formal anti-selective carbozincation reaction. Upon warming, the zinc carbenoid is stereochemically labile and isomerizes to its more stable form.

  10. 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.

  11. 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.

  12. 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.

  13. Gangs, Terrorism, and Radicalization

    Directory of Open Access Journals (Sweden)

    Scott Decker

    2011-01-01

    Full Text Available What can street gangs tell us about radicalization and extremist groups? At first glance, these two groups seem to push the boundaries of comparison. In this article, we examine the important similarities and differences across criminal, deviant, and extremist groups. Drawing from research on street gangs, this article explores issues such as levels of explanation,organizational structure, group process, and the increasingly important role of technology and the Internet in the context of radicalization. There are points of convergence across these groups, but it is important to understand the differences between these groups. This review finds little evidence to support the contention that American street gangs are becoming increasingly radicalized. This conclusion is based largely on organizational differences between gangs and terror groups.

  14. Sexuality Following Radical Prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Serefoglu, Ege C; Albersen, Maarten

    2017-01-01

    INTRODUCTION: Radical prostatectomies can result in urinary incontinence and sexual dysfunction. Traditionally, these issues have been studied separately, and the sexual problem that has received the most focus has been erectile dysfunction. AIM: To summarize the literature on sexually related side...... effects and their consequences after radical prostatectomy and focus on the occurrence and management of problems beyond erectile dysfunction. METHODS: The literature on sexuality after radical prostatectomy was reviewed through a Medline search. Original research using quantitative and qualitative...... methodologies was considered. Priority was given to studies exploring aspects of sexuality other than erectile function. MAIN OUTCOME MEASURES: The prevalence, predictive factors, and management of post-prostatectomy sexual problems beyond erectile dysfunction. RESULTS: Most patients will develop urinary...

  15. 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.

  16. 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

  17. 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.

  18. Radical dematerialization and degrowth

    Science.gov (United States)

    Kallis, Giorgos

    2017-05-01

    The emission targets agreed in Paris require a radical reduction of material extraction, use and disposal. The core claim of this article is that a radical dematerialization can only be part and parcel of degrowth. Given that capitalist economies are designed to grow, this raises the question of whether, and under what circumstances, the inevitable `degrowth' can become socially sustainable. Three economic policies are discussed in this direction: work-sharing, green taxes and public money. This article is part of the themed issue 'Material demand reduction'.

  19. Homegrown religious radicalization

    DEFF Research Database (Denmark)

    Khawaja, Iram

    and their families. Existing literature and ways of thinking about the social psychological process of radicalization will be reviewed, such as social identity theory and transformative learning theory, and a theoretical framework based on a focus on belonging, recognition and the sense of community will be proposed....... The framework will be utilized in an analysis of narratives from youngsters and parents of youngsters who have chosen a radicalized path in life. The paper will shed light on how the sense of and yearning for belonging and recognition have to be taken into account in our understanding of homegrown religious...

  20. Muon substituted free radicals

    International Nuclear Information System (INIS)

    Burkhard, P.; Fischer, H.; Roduner, E.; Strub, W.; Gygax, F.N.; Brinkman, G.A.; Louwrier, P.W.F.; McKenna, D.; Ramos, M.; Webster, B.C.

    1984-01-01

    Spin polarized energetic positive muons are injected as magnetic probes into unsaturated organic liquids. They are implemented via fast chemical processes ( -10 s) in various molecules. Of particular interest among these are muonium substituted free radicals. The technique allows determination of accurate rate coefficients for fast chemical reactions of radicals. Furthermore, radiochemical processes occuring in picoseconds after injection of the muon are studied. Of fundamental interest are also the structural and dynamical implications of substituting a proton by a muon, or in other terms, a hydrogen atom by a muonium atom. Selected examples for each of these three types of experiments are given. (Auth.)

  1. Unexpected in-situ Free Radical Generation and Catalysis to Ag/Polymer Nanocomposite

    Science.gov (United States)

    Pang, Yifan; Wei, Ruixue; Wang, Jintao; Wei, Liuhe; Li, Chunhui

    2015-07-01

    In this study, we discover unexpectedly that simple reaction of AgNO3 with oleic acid (OA) without solvent and surfactant could generate alkyl free radical which can catalyze double-bond polymerization of OA to form 1D polymeric oleic acid (POA) chain. In certain conditions, these POA chains circumvolute tightly each other to form microspheres and micro-plates in which monodisperse 4-5 nm Ag nanoparticles (NPs) were absorbed. It has been revealed that alkyl free radical generated during the redox reaction of carboxyl group of OA with Ag+ at relative low temperature. Then, the alkyl free radical catalyzed the double-bond polymerization of OA when the reaction temperature was further increased. Different from commonly-seen hydrophobic nanoparticles prepared in oleic acid-based microemulsion system, the nanocomposites cannot dispersed in n-hexane and could dispersed in ethanol and THF. The unusual dispersion behavior has been explained in terms of their structure and polarity of POA chain. The method combines the nucleation of Ag nanoparticles and the polymerization of monomer in a facile one-pot reaction, which provides a novel way for metal-polymer microsphere nanocomposite with low-cost, easy-operation and high-yield.

  2. 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.

  3. 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....

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. Violent Radicalization in Europe

    DEFF Research Database (Denmark)

    Dalgaard-Nielsen, Anja

    2010-01-01

    and foiled plots inspired by militant Islamism have grabbed European and American headlines. This article identifies and discusses empirical studies of radicalization and points to the strengths as well as the weaknesses characterizing these studies. The aim is to take stock of the current state of research...

  10. Gnosticism and Radical Feminism

    DEFF Research Database (Denmark)

    Cahana, Jonathan

    2016-01-01

    and place demand an explanation; my attempt to do so also takes into account the important differences between the gnostic and the radical feminist postures, notably the latter belief in progress and the former nostalgia for an ungendered era. Both the similarities and the differences, however, may offer...

  11. Counter radicalization development assistance

    OpenAIRE

    van Hippel, Karin

    2006-01-01

    The paper reviews current research and practice and recommends strategies for development agencies working in the Arab and Muslim world. It builds on the basic assumption that the realization of the Millennium Development Goals will be vital to reduce support for terrorism in the long term. Within this overall framework, emphasis is placed on particular programs that could be specifically applied to counter radicalization.

  12. Electromeric rhodium radical complexes

    NARCIS (Netherlands)

    Puschmann, F.F.; Harmer, J.; Stein, D.; Rüegger, H.; de Bruin, B.; Grützmacher, H.

    2010-01-01

    Radical changes: One single P-Rh-P angle determines whether the odd electron in the paramagnetic complex [Rh(trop2PPh)(PPh3)] is delocalized over the whole molecule (see picture, blue) or is localized on the P—Rh unit (red). The two energetically almost degenerate electromers exist in a fast

  13. Radical Behaviorist Epistemology.

    Science.gov (United States)

    Zuriff, G. E.

    1980-01-01

    Various epistemological positions attributed to radical behaviorism are reviewed, and their problems are discussed. It is suggested that these problems may be resolved by interpreting the criterion of truth generated by a science of behavior as logically analagous to the set of ethical values generated by that science. (Author/DB)

  14. Radically enhanced molecular recognition

    KAUST Repository

    Trabolsi, Ali

    2009-12-17

    The tendency for viologen radical cations to dimerize has been harnessed to establish a recognition motif based on their ability to form extremely strong inclusion complexes with cyclobis(paraquat-p-phenylene) in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chemistry, extending its practice beyond the traditional reliance on neutral and charged guests and hosts. In particular, transporting the concept of radical dimerization into the field of mechanically interlocked molecules introduces a higher level of control within molecular switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochemical potentials. In a tristable [2]rotaxane composed of a cyclobis(paraquat-p-phenylene) ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidation, it moves from the tetrathiafulvalene to the dioxynaphthalene, and on reduction, to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication. © 2010 Macmillan Publishers Limited. All rights reserved.

  15. The copper-catalysed Suzuki-Miyaura coupling of alkylboron reagents: disproportionation of anionic (alkyl)(alkoxy)borates to anionic dialkylborates prior to transmetalation.

    Science.gov (United States)

    Basnet, Prakash; Thapa, Surendra; Dickie, Diane A; Giri, Ramesh

    2016-09-25

    We report the first example of Cu(I)-catalysed coupling of alkylboron reagents with aryl and heteroaryl iodides that affords products in good to excellent yields. Preliminary mechanistic studies with alkylborates indicate that the anionic (alkoxy)(alkyl)borates, generated from alkyllithium and alkoxyboron reagents, undergo disproportionation to anionic dialkylborates and that both anionic alkylborates are active for transmetalation to a Cu(I)-catalyst. Results from a radical clock experiment and the Hammett plot imply that the reaction likely proceeds via a non-radical pathway.

  16. Kinetics of the reactions of alkyl radicals with HBr and DBr

    Science.gov (United States)

    Nicovich, J. M.; Van Dijk, C. A.; Kreutter, K. D.; Wine, P. H.

    1991-01-01

    The kinetics of the reactions CH3 + HBr, CD3 + HBr, CH3 + DBr, C2H5 + HBr, C2H5 + DBr, t-C4H9 + HBr, and t-C4H9 + DBr is studied as a function of temperature (257-430 K) and pressure (10-300 Torr of N2). Time-resolved resonance fluorescence detection of Br atom appearance following laser flash photolysis of RI was used in the experiments. Results show that the rates of all reactions increased as the temperature decreased.

  17. 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.

  18. 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)

  19. 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.

  20. 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.

  1. Radical Change by Entrepreneurial Design

    National Research Council Canada - National Science Library

    Roberts, Nancy C

    1998-01-01

    This article offers a conceptual framework to understand radical change. It opens with a typology that defines change in terms of its pace and scope, and defines radical change as the swift transformation of an entire system...

  2. Development of PhSCF2CF2SiMe3 as a Tandem Anion and Radical Tetrafluoroethylene Equivalent: Preparation of Tetrafluoroethyl-Substituted Alcohols and Tetrafluorotetrahydropyrans

    Czech Academy of Sciences Publication Activity Database

    Chernykh, Yana; Hlat-Glembová, Katarina; Klepetářová, Blanka; Beier, Petr

    -, č. 24 (2011), s. 4528-4531 ISSN 1434-193X R&D Projects: GA ČR GAP207/11/0421 Institutional research plan: CEZ:AV0Z40550506 Keywords : fluorine * alkylation * nucleophilic addition * radical reactions * oxygen heterocycles Subject RIV: CC - Organic Chemistry Impact factor: 3.329, year: 2011

  3. 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%.

  4. 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

  5. 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...

  6. 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 ...

  7. 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.

  8. Free radical explosive composition

    Science.gov (United States)

    Walker, Franklin E.; Wasley, Richard J.

    1979-01-01

    An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a getter additive comprising a compound or mixture of compounds capable of capturing or deactivating free radicals or ions under mechanical or electrical shock conditions and which is not an explosive. Exemplary getter additives are isocyanates, olefins and iodine.

  9. 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

  10. 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.

  11. Radical intermediates of low temperature radiolysis of di-tert-butylcyclohexano-18-crown-6/1-octanol extractant

    International Nuclear Information System (INIS)

    Zakurdaeva, O.A.; Nesterov, S.V.; Moscow State Univ.; Feldman, V.I.

    2013-01-01

    Intermediates of low temperature (77 K) X-rays radiolysis of 1-octanol and di-tert-butylcyclohexano-18-crown-6 solutions in 1-octanol were studied by ESR spectroscopy. Hydroxyalkyl CH 3 (CH 2 ) 6 C circle HOH and interior-type alkyl R 1 C circle HR 2 OH radicals were found to be main paramagnetic products stabilized in 1-octanol irradiated at 77 K. In addition to abovementioned radicals, macrocyclic -O-CH 2 -C circle H- and acyclic -C circle H-C(H)=O radicals produced from crown ether were identified in irradiated 1.0 M DtBuCH18C6 solution in octanol. No deviation in radiation-chemical yield of the stabilized acyclic radicals from the value expected in accord with 'additive' rule was observed in the latter case. It was supposed that macrocycle cleavage in DtBuCH18C6 occurred at early stages of radiolysis rather than in secondary radical reactions between products of 1-octanol radiolysis and crown ether. Meanwhile, alkyl radicals formed from 1-octanol can react with crown ether, resulting in formation of macrocyclic products of radiolysis. (orig.)

  12. Radical intermediates of low temperature radiolysis of di-tert-butylcyclohexano-18-crown-6/1-octanol extractant

    Energy Technology Data Exchange (ETDEWEB)

    Zakurdaeva, O.A.; Nesterov, S.V. [Russian Academy of Sciences, Moscow (Russian Federation). Enikolopov Institute of Synthetic Polymer Materials; Moscow State Univ. (Russian Federation). Dept. of Chemistry; Feldman, V.I. [Moscow State Univ. (Russian Federation). Dept. of Chemistry

    2013-03-01

    Intermediates of low temperature (77 K) X-rays radiolysis of 1-octanol and di-tert-butylcyclohexano-18-crown-6 solutions in 1-octanol were studied by ESR spectroscopy. Hydroxyalkyl CH{sub 3}(CH{sub 2}){sub 6}C {sup circle} HOH and interior-type alkyl R{sub 1}C {sup circle} HR{sub 2}OH radicals were found to be main paramagnetic products stabilized in 1-octanol irradiated at 77 K. In addition to abovementioned radicals, macrocyclic -O-CH{sub 2}-C {sup circle} H- and acyclic -C {sup circle} H-C(H)=O radicals produced from crown ether were identified in irradiated 1.0 M DtBuCH18C6 solution in octanol. No deviation in radiation-chemical yield of the stabilized acyclic radicals from the value expected in accord with 'additive' rule was observed in the latter case. It was supposed that macrocycle cleavage in DtBuCH18C6 occurred at early stages of radiolysis rather than in secondary radical reactions between products of 1-octanol radiolysis and crown ether. Meanwhile, alkyl radicals formed from 1-octanol can react with crown ether, resulting in formation of macrocyclic products of radiolysis. (orig.)

  13. Radical distinction : Support for radical left and radical right parties in Europe

    NARCIS (Netherlands)

    Rooduijn, Matthijs; Burgoon, Brian; van Elsas, Erika J.; van de Werfhorst, Herman G.

    2017-01-01

    Support for radical parties on both the left and right is on the rise, fueling intuition that both radicalisms have similar underpinnings. Indeed, existing studies show that radical left and right voters have overlapping positions and preferences. In this article, however, we focus on the

  14. 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.

  15. Overexpressed human metallothionein IIA gene protects Chinese hamster ovary cells from killing by alkylating agents

    International Nuclear Information System (INIS)

    Kaina, B.; Lohrer, H.; Karin, M.; Herrlich, P.

    1990-01-01

    Experiments were designed to detect survival advantages that cells gain by overexpressing metallothionein (MT). Chinese hamster ovary K1-2 cells and an x-ray-sensitive derivative were transfected with a bovine papillomavirus (BPV)-linked construct carrying the human metallothionein IIA (hMT-IIA) gene. Transfectants survived 40-fold higher levels of cadmium chloride, harbored at least 30 copies of hMT-IIA, and contained 25- to 166-fold more MT than the parent cells. Even under conditions of reduced glutathione synthesis, the transfectants were not more resistant to the lethal effects of ionizing radiation and bleomycin than the parent cells. Thus free radicals generated by these agents cannot be scavenged efficiently by MT in vivo. The hMT-IIA transfectants, however, but not control transfectants harboring a BPV-MT promoter-neo construct, tolerated significantly higher doses of the alkylating agents N-methyl-N-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine. Resistance and MT overexpression occurred irrespective of selection and cultivation in cadmium and zinc. There was no increase in resistance to methyl methanesulfonate and N-hydroxyethyl-N-chloroethylnitrosourea. MT did not affect the degree of overall DNA methylation after N-methyl-N-nitrosourea treatment nor the level of O6-methylguanine-DNA methyltransferase. The results suggest that MT participates as a cofactor or regulatory element in repair or tolerance of toxic alkylation lesions

  16. Overexpressed human metallothionein IIA gene protects Chinese hamster ovary cells from killing by alkylating agents

    Energy Technology Data Exchange (ETDEWEB)

    Kaina, B.; Lohrer, H.; Karin, M.; Herrlich, P. (Kernforschungszentrum Karlsruhe, Karlsruhe (Germany, F.R.))

    1990-04-01

    Experiments were designed to detect survival advantages that cells gain by overexpressing metallothionein (MT). Chinese hamster ovary K1-2 cells and an x-ray-sensitive derivative were transfected with a bovine papillomavirus (BPV)-linked construct carrying the human metallothionein IIA (hMT-IIA) gene. Transfectants survived 40-fold higher levels of cadmium chloride, harbored at least 30 copies of hMT-IIA, and contained 25- to 166-fold more MT than the parent cells. Even under conditions of reduced glutathione synthesis, the transfectants were not more resistant to the lethal effects of ionizing radiation and bleomycin than the parent cells. Thus free radicals generated by these agents cannot be scavenged efficiently by MT in vivo. The hMT-IIA transfectants, however, but not control transfectants harboring a BPV-MT promoter-neo construct, tolerated significantly higher doses of the alkylating agents N-methyl-N-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine. Resistance and MT overexpression occurred irrespective of selection and cultivation in cadmium and zinc. There was no increase in resistance to methyl methanesulfonate and N-hydroxyethyl-N-chloroethylnitrosourea. MT did not affect the degree of overall DNA methylation after N-methyl-N-nitrosourea treatment nor the level of O6-methylguanine-DNA methyltransferase. The results suggest that MT participates as a cofactor or regulatory element in repair or tolerance of toxic alkylation lesions.

  17. Overexpressed human metallothionein IIA gene protects Chinese hamster ovary cells from killing by alkylating agents.

    Science.gov (United States)

    Kaina, B; Lohrer, H; Karin, M; Herrlich, P

    1990-01-01

    Experiments were designed to detect survival advantages that cells gain by overexpressing metallothionein (MT). Chinese hamster ovary K1-2 cells and an x-ray-sensitive derivative were transfected with a bovine papillomavirus (BPV)-linked construct carrying the human metallothionein IIA (hMT-IIA) gene. Transfectants survived 40-fold higher levels of cadmium chloride, harbored at least 30 copies of hMT-IIA, and contained 25- to 166-fold more MT than the parent cells. Even under conditions of reduced glutathione synthesis, the transfectants were not more resistant to the lethal effects of ionizing radiation and bleomycin than the parent cells. Thus free radicals generated by these agents cannot be scavenged efficiently by MT in vivo. The hMT-IIA transfectants, however, but not control transfectants harboring a BPV-MT promoter-neo construct, tolerated significantly higher doses of the alkylating agents N-methyl-N-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine. Resistance and MT overexpression occurred irrespective of selection and cultivation in cadmium and zinc. There was no increase in resistance to methyl methanesulfonate and N-hydroxyethyl-N-chloroethylnitrosourea. MT did not affect the degree of overall DNA methylation after N-methyl-N-nitrosourea treatment nor the level of O6-methylguanine-DNA methyltransferase. The results suggest that MT participates as a cofactor or regulatory element in repair or tolerance of toxic alkylation lesions. Images PMID:2320583

  18. One-electron reduction of 2- and 6-methyl-1,4-naphthoquinone bioreductive alkylating agents

    International Nuclear Information System (INIS)

    Wilson, I.; Wardman, P.; Lin, T.S.; Sartorelli, A.C.

    1986-01-01

    The semiquinones, Q.-, of derivatives of 2- and 6-methyl-1,4-naphthoquinones, some incorporating leaving groups with substituents such as CH 2 Br or CH 2 OCONHCH 3 , have been produced by radiolytic reduction of Q by (CH 3 )2COH radicals. The absorption spectra and decay kinetics of Q.- were all closely similar to that produced from 2-methyl-1,4-naphthoquinone, with no evidence for unimolecular elimination of a leaving group in the semiquinone form, but immediate loss of leaving group upon two-electron reduction of Q to the hydroquinone. The redox equilibria between Q/Q.- and O2/O2.- were characterized, and reduction potentials of the couples Q/Q.- in water at pH 7.6 were calculated. The implications of these observations for the use of these compounds as bioreductive alkylating agents or as radiosensitizers with potential selective activity toward hypoxic cells are discussed

  19. Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide.

    Science.gov (United States)

    Belloche, Arnaud; Garrod, Robin T; Müller, Holger S P; Menten, Karl M

    2014-09-26

    The largest noncyclic molecules detected in the interstellar medium (ISM) are organic with a straight-chain carbon backbone. We report an interstellar detection of a branched alkyl molecule, iso-propyl cyanide (i-C3H7CN), with an abundance 0.4 times that of its straight-chain structural isomer. This detection suggests that branched carbon-chain molecules may be generally abundant in the ISM. Our astrochemical model indicates that both isomers are produced within or upon dust grain ice mantles through the addition of molecular radicals, albeit via differing reaction pathways. The production of iso-propyl cyanide appears to require the addition of a functional group to a nonterminal carbon in the chain. Its detection therefore bodes well for the presence in the ISM of amino acids, for which such side-chain structure is a key characteristic. Copyright © 2014, American Association for the Advancement of Science.

  20. 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...

  1. 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.

  2. Catalysis of Radical Reactions: A Radical Chemistry Perspective.

    Science.gov (United States)

    Studer, Armido; Curran, Dennis P

    2016-01-04

    The area of catalysis of radical reactions has recently flourished. Various reaction conditions have been discovered and explained in terms of catalytic cycles. These cycles rarely stand alone as unique paths from substrates to products. Instead, most radical reactions have innate chains which form products without any catalyst. How do we know if a species added in "catalytic amounts" is a catalyst, an initiator, or something else? Herein we critically address both catalyst-free and catalytic radical reactions through the lens of radical chemistry. Basic principles of kinetics and thermodynamics are used to address problems of initiation, propagation, and inhibition of radical chains. The catalysis of radical reactions differs from other areas of catalysis. Whereas efficient innate chain reactions are difficult to catalyze because individual steps are fast, both inefficient chain processes and non-chain processes afford diverse opportunities for catalysis, as illustrated with selected examples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Explaining unexpected data via competitive equilibria and processes in radical reactions with reversible deactivation.

    Science.gov (United States)

    Konkolewicz, Dominik; Krys, Pawel; Matyjaszewski, Krzysztof

    2014-10-21

    lead to an acceleration of the reaction during the initial period. Similarly, in Cu mediated atom transfer radical polymerization (ATRP) with initiators for continuous radical regeneration (ICAR) initiated by a conventional radical initiator, the rate of polymerization should not depend on either the alkyl halide concentration or the Cu concentration. However, experiments show that the rate could be 10 times faster with alkyl halide than without alkyl halide. Finally, in aqueous media, the presence of active alkyl halides can appear to stop the disproportionation of Cu(I) complexes. These unusual data point to a more complex mechanism than originally envisioned, and in fact all these counterintuitive observations can be explained by the concept of competing equilibria and processes. In these cases, the presence of two or more reactions competing for the same reagent typically causes one pathway to dominate, while the rate of the other pathways are diminished. Alternatively, the competing pathways and processes can cause one or more reversible or pseudoreversible reactions to be imbalanced and lead to products distinct from the case where rates of forward and reverse reactions are balanced. In this Account, the concept of competitive processes and equilibria is developed and used to explain each of the unusual observations highlighted above.

  4. Manipulating radicals: Using cobalt to steer radical reactions

    OpenAIRE

    Chirilă, A.

    2017-01-01

    This thesis describes research aimed at understanding and exploiting metallo-radical reactivity and explores reactions mediated by square planar, low-spin cobalt(II) complexes. A primary goal was to uncover novel reactivity of discrete cobalt(III)-bound carbene radicals generated upon reaction of the cobalt(II) catalysts with carbene precursors. Another important goal was to replace cobalt(II)-porphyrin catalysts with cheaper and easier to prepare metallo-radical analogues. Therefore the cata...

  5. 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

  6. 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)

  7. 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.

  8. Time course evaluation of N-nitrosodialkylamines-induced DNA alkylation and oxidation in liver of mosquito fish

    International Nuclear Information System (INIS)

    Chao, M.-R.; Chang, Y.-Z.; Wong, R.-H.; Hu, C.-W.

    2009-01-01

    Here we simultaneously measured N7-alkylguanines and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in liver of small fish, respectively, to assess the time course of the formation and removal of alkylation and oxidative damage to DNA caused by N-nitrosodialkylamines. Mosquito fish (Gambusia affinis) were killed at various times during (4 days) and post-exposure (16 days) to N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) alone or their combination with concentrations of 10 and 50 mg/l. The modified guanine adducts were sensitively and selectively quantitated by isotope-dilution LC-MS/MS methods. During exposure, N7-methylguanine (N7-MeG) and N7-ethylguanine (N7-EtG) in liver DNA increased with the duration and dose of N-nitrosodialkylamine exposure, while 8-oxodG was dose-dependently induced within 1 day. It was found that NDMA formed substantially more N7-alkylated guanines and 8-oxodG than NDEA on the basis of adducts formed per micromolar concentration, suggesting that NDMA can be more easily bioactivated than NDEA to form reactive alkylating agents with the concomitant formation of oxygen radicals. After cessation of exposure, N7-alkylguanines remained elevated for 1 day and then gradually decreased over time but still higher than the background levels, even at day 16 (half-lives of 7-8 days). However, 8-oxodG was excised quickly from liver DNA and returned to the background level within 4 days post-exposure (half-lives less than 2 days). Taken together, this study firstly demonstrated that in addition to alkylation, N-nitrosodialkylamines can concurrently cause oxidative damage to DNA in vivo

  9. Reaction mechanism and kinetics of the degradation of terbacil initiated by OH radical - A theoretical study

    Science.gov (United States)

    Ponnusamy, S.; Sandhiya, L.; Senthilkumar, K.

    2018-02-01

    The reaction of terbacil with OH radical is studied by using electronic structure calculations. The reaction of terbacil with OH radical is found to proceed by H-atom abstraction, Cl-atom abstraction and OH addition reactions. The initially formed alkyl radical will undergo atmospheric transformation in the presence of molecular oxygen leading to the formation of peroxy radical. The reaction of peroxy radical with other atmospheric oxidants, such as HO2 and NO radicals is studied. The rate constant is calculated for the H-atom abstraction reactions over the temperature range of 200-1000 K. The results obtained from electronic structure calculations and kinetic study show that the H-atom abstraction reaction is more favorable. The calculated lifetime of terbacil is 24 h in normal atmospheric OH concentration. The rate constant calculated for H-atom abstraction reactions is 6 × 10-12, 4.4 × 10-12 and 3.2 × 10-12 cm3molecule-1s-1, respectively which is in agreement with the previous literature value of 1.9 × 10-12 cm3molecule-1s-1.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Thermochemical Stability of alpha-Amino-alpha-carbonylmethyl Radicals and Their Resonance As Measured by ESR.

    Science.gov (United States)

    Welle, Frank M.; Beckhaus, Hans-Dieter; Rüchardt, Christoph

    1997-02-07

    ESR spectra of the captodative alpha-amino-alpha-carbonylmethyl radicals 8 have been recorded. No coalescence temperature for the rotation of the two NMe groups was found at temperatures below the decomposition temperature of the radicals. From known coalescence temperatures and rotational barriers of substituted methyl radicals the rotational barrier of >/=17 kcal mol(-)(1) was estimated for the (*)C-N bond in the radicals 8. Enthalpies DeltaH(diss) and entropies DeltaS(diss) of the homolytic dissociation of 7a,c,d into 8a,c,d have been obtained from equilibrium measurements by ESR. By correcting for substituent interaction enthalpies in 7 (steric and geminal), a radical stabilization enthalpy RSE = -20.7 +/- 1.0 kcal mol(-)(1) was obtained for 8. By addition of the known RSEs of dialkylamino- and carbonyl groups, a RSE = -9.9 kcal mol(-)(1) is predicted for 8. The difference between the experimental and predicted values of 10.8 kcal mol(-)(1) is attributed to a synergistic captodative substituent effect. A linear correlation between the radical stabilization enthalpies of the radicals 8 and of other mono- and disubstituted alkyl radicals and their ESR aH(alpha) coupling constants was found. According to this correlation the reduction of aH(alpha) by 1 G corresponds to an increase in RSE of 1.57 kcal mol(-)(1). The large resonance of the captodative alpha-amino-alpha-carbonylmethyl radicals 3, expressed by their high RSE, their small aH(alpha) coupling constant, and their high rotational barrier, can be rationalized by a strong interaction between the alpha-amino and the alpha-carbonyl groups similar to that in amides and expressed in the resonance structures 6.

  17. 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.

  18. 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.

  19. Radical scavenging activity of lipophilized products from lipase-catalyzed transesterification of triolein with cinnamic and ferulic acids.

    Science.gov (United States)

    Choo, Wee-Sim; Birch, Edward John

    2009-02-01

    Lipase-catalyzed transesterification of triolein with cinnamic and ferulic acids using an immobilized lipase from Candida antarctica (E.C. 3.1.1.3) was conducted to evaluate the antioxidant activity of the lipophilized products as model systems for enhanced protection of unsaturated oil. The lipophilized products were identified using ESI-MS. Free radical scavenging activity was determined using the DPPH radical method. The polarity of the solvents proved important in determining the radical scavenging activity of the substrates. Ferulic acid showed much higher radical scavenging activity than cinnamic acid, which has limited activity. The esterification of cinnamic acid and ferulic acid with triolein resulted in significant increase and decrease in the radical scavenging activity, respectively. These opposite effects were due to the effect of addition of electron-donating alkyl groups on the predominant mechanism of reaction (hydrogen atom transfer or electron transfer) of a species with DPPH. The effect of esterification of cinnamic acid was confirmed using ethyl cinnamate which greatly enhances the radical scavenging activity. Although, compared to the lipophilized cinnamic acid product, the activity was lower. The radical scavenging activity of the main component isolated from lipophilized cinnamic acid product using solid phase extraction, monocinnamoyl dioleoyl glycerol, was as good as the unseparated mixture of lipophilized product. Based on the ratio of a substrate to DPPH concentration, lipophilized ferulic acid was a much more efficient radical scavenger than lipophilized cinnamic acid.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. Free radicals and polarized targets

    Science.gov (United States)

    Bunyatova, E. I.

    2004-06-01

    Many free radicals were added to organic compounds in search of high proton and deuteron polarizations. Few found practical application. A short review is presented, and special attention is given to some stable nitroxyl radicals which have lately been admixed to organic compounds solid at room temperature, in particular to scintillators.

  5. Free radicals and polarized targets

    Energy Technology Data Exchange (ETDEWEB)

    Bunyatova, E.I. E-mail: bunyatel@nusun.jinr.ru

    2004-06-21

    Many free radicals were added to organic compounds in search of high proton and deuteron polarizations. Few found practical application. A short review is presented, and special attention is given to some stable nitroxyl radicals which have lately been admixed to organic compounds solid at room temperature, in particular to scintillators.

  6. Hydroxyl radical reactivity with diethylhydroxylamine

    International Nuclear Information System (INIS)

    Gorse, R.A. Jr.; Lii, R.R.; Saunders, B.B.

    1977-01-01

    Diethylhydroxylamine (DEHA) reacts with gas-phase hydroxyl radicals on every third collision, whereas the corresponding reaction in aqueous solution is considerably slower. The high gas-phase reactivity explains the predicted inhibitory effect of DEHA in atmospheric smog processes. Results from the studies in the aqueous phase are helpful in predicting the mechanism of the reaction of DEHA with hydroxyl radicals

  7. 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.)

  8. 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

  9. 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

  10. Oxidative stability of fatty acid alkyl esters: a review.

    Directory of Open Access Journals (Sweden)

    Michal Angelovič

    2015-12-01

    Full Text Available The purpose of this study was to investigate and to process the current literary knowledge of the physico-chemical properties of vegetable oil raw used for biodiesel production in terms of its qualitative stability. An object of investigation was oxidative stability of biodiesel. In the study, we focused on the qualitative physico-chemical properties of vegetable oils used for biodiesel production, oxidative degradation and its mechanisms, oxidation of lipids, mechanisms of autooxidation, effectivennes of different synthetic antioxidants in relation to oxidative stability of biodiesel and methods of oxidative stability determination. Knowledge of the physical and chemical properties of vegetable oil as raw material and the factors affecting these properties is critical for the production of quality biodiesel and its sustainability. According to the source of oilseed, variations in the chemical composition of the vegetable oil are expressed by variations in the molar ratio among different fatty acids in the structure. The relative ratio of fatty acids present in the raw material is kept relatively constant after the transesterification reaction. The quality of biodiesel physico-chemical properties is influenced by the chain length and the level of unsaturation of the produced fatty acid alkyl esters. A biodiesel is thermodynamically stable. Its instability primarily occurs from contact of oxygen present in the ambient air that is referred to as oxidative instability. For biodiesel is oxidation stability a general term. It is necessary to distinguish ‘storage stability' and ‘thermal stability', in relation to oxidative degradation, which may occur during extended periods of storage, transportation and end use. Fuel instability problems can be of two related types, short-term oxidative instability and long-term storage instability. Storage instability is defined in terms of solid formation, which can plug nozzles, filters, and degrade engine

  11. 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.

  12. Radical cations in condensed phases

    Energy Technology Data Exchange (ETDEWEB)

    Symons, M.C.R. (Leicester Univ. (UK). Dept. of Chemistry)

    The subject is covered in sections, entitled: introduction (scope of present Review); preparative procedures; alkane and cycloalkane cations; alkene and cyclic alkene cations; alkyl-halide cations; alcohol and ether cations; carbonyl cations (aldehyde, ketone and ester cations); sulphur-centred cations; selenium-centred cations; nitrogen-centred cations; phosphorus-centred cations; tin- and lead-centred cations; aromatic cations; five membered hetero-aromatic cations; vinyl cations; inorganic cations.

  13. Molecular weight growth in Titan's atmosphere: branching pathways for the reaction of 1-propynyl radical (H3CC≡C˙) with small alkenes and alkynes.

    Science.gov (United States)

    Kirk, Benjamin B; Savee, John D; Trevitt, Adam J; Osborn, David L; Wilson, Kevin R

    2015-08-28

    The reaction of small hydrocarbon radicals (i.e.˙CN, ˙C2H) with trace alkenes and alkynes is believed to play an important role in molecular weight growth and ultimately the formation of Titan's characteristic haze. Current photochemical models of Titan's atmosphere largely assume hydrogen atom abstraction or unimolecular hydrogen elimination reactions dominate the mechanism, in contrast to recent experiments that reveal significant alkyl radical loss pathways during reaction of ethynyl radical (˙C2H) with alkenes and alkynes. In this study, the trend is explored for the case of a larger ethynyl radical analogue, the 1-propynyl radical (H3CC[triple bond, length as m-dash]C˙), a likely product from the high-energy photolysis of propyne in Titan's atmosphere. Using synchrotron vacuum ultraviolet photoionization mass spectrometry, product branching ratios are measured for the reactions of 1-propynyl radical with a suite of small alkenes (ethylene and propene) and alkynes (acetylene and d4-propyne) at 4 Torr and 300 K. Reactions of 1-propynyl radical with acetylene and ethylene form single products, identified as penta-1,3-diyne and pent-1-en-3-yne, respectively. These products form by hydrogen atom loss from the radical-adduct intermediates. The reactions of 1-propynyl radical with d4-propyne and propene form products from both hydrogen atom and methyl loss, (-H = 27%, -CH3 = 73%) and (-H = 14%, -CH3 = 86%), respectively. Together, these results indicate that reactions of ethynyl radical analogues with alkenes and alkynes form significant quantities of products by alkyl loss channels, suggesting that current photochemical models of Titan over predict both hydrogen atom production as well as the efficiency of molecular weight growth in these reactions.

  14. Radical production in biological systems

    International Nuclear Information System (INIS)

    Johnson, J.R.; Akabani, G.

    1994-10-01

    This paper describes our effort to develop a metric for radiation exposure that is more fundamental than adsorbed dose and upon which a metric for exposure to chemicals could be based. This metric is based on the production of radicals by the two agents. Radicals produced by radiation in biological systems commonly assumed to be the same as those produced in water despite the presence of a variety of complex molecules. This may explain why the extensive efforts to describe the relationship between energy deposition (track structure) and molecular damage to DNA, based on the spectrum of radicals produced, have not been successful in explaining simple biological effects such as cell killing. Current models assume that DNA and its basic elements are immersed in water-like media and only model the production and diffusion of water-based radicals and their interaction with DNA structures; these models lack the cross sections associated with each macro-component of DNA and only treat water-based radicals. It has been found that such models are not realistic because DNA is not immersed in pure water. A computer code capable of simulating electron tracks, low-energy electrons, energy deposition in small molecules, and radical production and diffusion in water like media has been developed. This code is still in at a primitive stage and development is continuing. It is being used to study radical production by radiation, and radical diffusion and interactions in simple molecular systems following their production. We are extending the code to radical production by chemicals to complement our PBPK modeling efforts. It therefore has been developed primarily for use with radionuclides that are in biological materials, and not for radiation fields

  15. 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

  16. Guest Editorial: Processes of Radicalization and De-Radicalization

    Directory of Open Access Journals (Sweden)

    Donatella Della Porta

    2012-05-01

    Full Text Available The study of radicalization and de-radicalization, understood as processes leading towards the increased or decreased use of political violence, is central to the question of how political violence emerges, how it can be prevented, and how it can be contained. The focus section of this issue of the International Journal of Conflict and Violence addresses radicalization and de-radicalization, seeking to develop a more comprehensive understanding of the processes, dynamics, and mechanisms involved and taking an interdisciplinary approach to overcome the fragmentation into separate disciplines and focus areas. Contributions by Pénélope Larzillière, Felix Heiduk, Bill Kissane, Hank Johnston, Christian Davenport and Cyanne Loyle, Veronique Dudouet, and Lasse Lindekilde address repressive settings, legitimacy, institutional aspects, organizational outcomes, and dynamics in Europe, Asia, Africa, and North and South America.

  17. 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

  18. Laboratory studies of nitrate radical chemistry - application to atmospheric processes

    Energy Technology Data Exchange (ETDEWEB)

    Noremsaune, Ingse

    1997-12-31

    This thesis studies atmospheric chemistry and tries in particular to fill gaps in the data base of atmospheric reactions. It studies the nitrate radical reactions with chloroethenes and with but-2-yne (2-butyne). The mechanisms and rate coefficients for the NO{sub 3}-initiated degradation of the chloroethenes and 2-butyne were investigated by means of the static reaction chamber and the fast flow-discharge technique. The reactions between the nitrate radical and the chloroethenes were studied at atmospheric pressure in a reaction chamber with synthetic air as bath gas. FTIR (Fourier Transform InfraRed spectroscopy) spectroscopy was used to follow the reactions and to identify the products. Products were observed for the reactions with (E)-1,2-dichloroethene and tetrachloroethene, although the absorption bands are weak. The alkyl peroxynitrate and nitrate compounds form very strong and characteristic absorption bands. The rate coefficients for the reactions between NO{sub 3} and the chloroethenes were investigated at room temperature by three different methods. The results are given in tables. 132 refs., 44 figs., 21 tabs.

  19. CONTINENT RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    Yu. P. Sernyak

    2013-01-01

    Full Text Available Objective: to evaluate the impact of dissection of the dorsal venous complex without pre-ligation, suturing, or coagulation during radical prostatectomy (RPE in patients with localized prostate cancer (PC on the quality of surgery and the function of urinary retention.Subjects and methods. The data of 42 patients who had undergone posterior and anterior anatomical repair and vesicourethral anastomosis using a V-lock suture after prostatectomy were analyzed. All the patients were divided into 2 groups. Group 1 consisted of 22 patients in whom the dorsal venous complex was closed using a 3-0 vicryl suture before urethral dissection. Group 2 included 20 patients in whom the urethra was dissected without suturing the venous complex.Results. In group 1, complete urinary retention after catheter removal was noted in 9 (40.9 % and 15 (68 % patients within 24 hours and after 3 months, respectively. Following 12 months, two (9 % patients were observed to have partial mild urinary incontinence (as many as 2 pads per day. Group 2 patients showed complete urinary retention in 17 (85 % cases on the first day after catheter removal; all the patients retained urine 3 months later.Conclusion. In patients with localized PC, dissection of the dorsal venous complex without presuturing during laparoscopic RPE exerts a considerable impact on the preservation of urinary retention, namely 45% more of the patients reported complete urinary retention in early periods and 10 % more did this in later periods. At the same time, there was no statistically significant increase in intraoperative blood loss (p > 0.05, the number of positive edges, or biochemical recurrences.

  20. CONTINENT RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    Yu. P. Sernyak

    2014-07-01

    Full Text Available Objective: to evaluate the impact of dissection of the dorsal venous complex without pre-ligation, suturing, or coagulation during radical prostatectomy (RPE in patients with localized prostate cancer (PC on the quality of surgery and the function of urinary retention.Subjects and methods. The data of 42 patients who had undergone posterior and anterior anatomical repair and vesicourethral anastomosis using a V-lock suture after prostatectomy were analyzed. All the patients were divided into 2 groups. Group 1 consisted of 22 patients in whom the dorsal venous complex was closed using a 3-0 vicryl suture before urethral dissection. Group 2 included 20 patients in whom the urethra was dissected without suturing the venous complex.Results. In group 1, complete urinary retention after catheter removal was noted in 9 (40.9 % and 15 (68 % patients within 24 hours and after 3 months, respectively. Following 12 months, two (9 % patients were observed to have partial mild urinary incontinence (as many as 2 pads per day. Group 2 patients showed complete urinary retention in 17 (85 % cases on the first day after catheter removal; all the patients retained urine 3 months later.Conclusion. In patients with localized PC, dissection of the dorsal venous complex without presuturing during laparoscopic RPE exerts a considerable impact on the preservation of urinary retention, namely 45% more of the patients reported complete urinary retention in early periods and 10 % more did this in later periods. At the same time, there was no statistically significant increase in intraoperative blood loss (p > 0.05, the number of positive edges, or biochemical recurrences.

  1. Oxidation and Free Radical Decay in Vitamin E-stabilized, Radiation Cross-linked UHMWPE

    International Nuclear Information System (INIS)

    Oral, E.

    2006-01-01

    A novel a-tocopherol (vitamin E, α-T)-stabilized, cross-linked ultra-high molecular weight polyethylene (UHMWPE) (αTPE) was developed for total joint arthroplasty as a bearing surface with low wear and improved mechanical properties. Accelerated aging showed α-T protects irradiated UHMWPE against oxidation. However, accelerated aging may not truly reflect in vivo and shelf oxidation. We used real-time aging to monitor the evolution of oxidation and free radical signals of α-T to determine the mechanism of oxidative stability. UHMWPE blocks (30x30x10 mm) were machined and γ-irradiated (85 kGy) in argon. The blocks were doped in α-T for 5 hours at 120 degree and homogenized for 64 hours at 120 degree in argon, packaged in vacuum and γ-sterilized (25 kGy). Samples were aged in air at room temperature, in air at 40 degree and in water at 40 degree. Measurements were at 1, 2, 3, 4 and 7 months. Sections cut from the aged blocks (150μm) were boiled in hexane overnight to extract free species and evaluated by FTIR. Oxidation indices were calculated by taking the area under the carbonyl peak and normalizing it to a skeletal peak. ESR was used to determine the content and type of free radicals. Control was 100-kGy irradiated, unstabilized UHMWPE. αTPE showed a small amount of oxidation, which stabilized after 2 months. This indicated that the decay of the hydroperoxides formed by the reaction of the residual free radicals with oxygen was exhausted by α-T due to its ability to scavenge free radicals. In contrast, control UHMWPE continued to oxidize because the residual free radicals likely continued to form hydroperoxides and additional free radicals, furthering the oxidation reactions. There was a shift in the free radical signature of both αTPE and control from the sextet alkyl/allyl radicals to a sharp singlet during aging. Most likely, trapped free radicals move along the crystal stems until they react with another free radical or until they reach the crystal

  2. 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

  3. 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)

  4. 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.

  5. 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.

  6. Redox Properties of Free Radicals.

    Science.gov (United States)

    Neta, P.

    1981-01-01

    Describes pulse radiolysis as a useful means in studing one-electron redox potentials. This method allows the production of radicals and the determination of their concentration and rates of reaction. (CS)

  7. Penile rehabilitation after radical prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Ohl, Dana A; Ralph, David

    2013-01-01

    The pathophysiology of erectile dysfunction after radical prostatectomy (RP) is believed to include neuropraxia, which leads to temporarily reduced oxygenation and subsequent structural changes in penile tissue. This results in veno-occlusive dysfunction, therefore, penile rehabilitation programmes...

  8. 8-METHOXYNEORAUTENOL AND RADICAL SCAVENGING ...

    African Journals Online (AJOL)

    Preferred Customer

    8-METHOXYNEORAUTENOL AND RADICAL SCAVENGING FLAVONOIDS FROM. ERYTHRINA ABYSSINICA. Abiy Yenesew1*, Hannington Twinomuhwezi1 ... shown that the plant elaborates alkaloids [1], flavanones, pterocarpans, chalcones and isoflavonoids [1, 3]; some of which have been shown to have antimicrobial ...

  9. Radical Change by Entrepreneurial Design

    National Research Council Canada - National Science Library

    Roberts, Nancy C

    1998-01-01

    .... Radical change by entrepreneurial design then becomes the focal point, in order to acquaint the reader with the strategies and tactics of well-known entrepreneurs who have been successful in molding...

  10. Ecoporn, Irrationalities and Radical Environmentalism

    OpenAIRE

    Măntescu, Liviu

    2016-01-01

    This study explores the ‘irrationalities’ of deep ecology activism in the context of radical environmentalism by using the empirical example of ecoporn. Fuck For Forest is an environmental Non-Governmental Organisation which undertakes fund-raising for re-forestation and forest protection by means of pornography. Following twelve months of ethnographic fieldwork, this study presents first research results on a radical environmental project which does not promote democratic and established pro...

  11. [Urine derivation after radical cystectomy].

    Science.gov (United States)

    Jarabák, J; Zachoval, R; Vik, V

    2014-01-01

    Radical cystectomy, performed both for the treatment of cancer and other conditions, needs to be followed by ensuring the derivation of urine. The aim of this work is to summarize the possibilities of urine derivation after cystectomy, their advantages, disadvantages and long-term results. A review article summarising relevant literature and the team of authors own experience. This work compares advantages and risks of different types of urine derivation following radical cystectomy.

  12. Characterization of alkyl phenols in cashew (Anacardium occidentale) products and assay of their antioxidant capacity.

    Science.gov (United States)

    Trevisan, M T S; Pfundstein, B; Haubner, R; Würtele, G; Spiegelhalder, B; Bartsch, H; Owen, R W

    2006-02-01

    In this study the content of anacardic acids, cardanols and cardols in cashew apple, nut (raw and roasted) and cashew nut shell liquid (CNSL) were analysed. The higher amounts (353.6 g/kg) of the major alkyl phenols, anacardic acids were detected in CNSL followed by cashew fibre 6.1 g/kg) while the lowest (0.65 g/kg) amounts were detected in roasted cashew nut. Cashew apple and fibre contained anacardic acids exclusively, whereas CNSL also contained an abundance of cardanols and cardols. Cashew nut (raw and roasted) also contained low amounts of hydroxy alkyl phenols. Cashew nut shell liquid was used for a basic fractionation of the alkyl phenol classes and the individual anacardic acids, major cardanols and cardols were purified to homogeneity from these fractions by semi-preparative HPLC and definitively identified by nano-ESI-MS-MS, GC-MS and NMR analyses. The hexane extracts (10 mg/ml) of all cashew products tested plus CNSL, displayed significant antioxidant capacity. Cashew nut shell liquid was the more efficient (inhibition=100%) followed by the hexane extract of cashew fibre (94%) and apple (53%). The antioxidant capacity correlated significantly (P4.0 mM). The data shows that of these substances, anacardic-1 was by far the more potent antioxidant (IC50=0.27 mM) compared to cardol-1 (IC50=1.71 mM) and cardanol-1 (IC50>4.0 mM). The antioxidant capacity of anacardic acid-1 is more related to inhibition of superoxide generation (IC50=0.04 mM) and xanthine oxidase (IC50=0.30 mM) than to scavenging of hydroxyl radicals. At present a substantial amount of cashew fibre is mostly used in formulations of animal or poultry feeds. The data presented in this study, indicates that this waste product along with CNSL, both of which contain high contents of anacardic acids, could be better utilized in functional food formulations and may represent a cheap source of cancer chemopreventive agents.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. Catalytic Hydrogenation Activity and Electronic Structure Determination of Bis(arylimidazol-2-ylidene)pyridine Cobalt Alkyl and Hydride Complexes

    Science.gov (United States)

    Yu, Renyuan Pony; Darmon, Jonathan M.; Milsmann, Carsten; Margulieux, Grant W.; E. Stieber, S. Chantal; DeBeer, Serena

    2013-01-01

    The bis(arylimidazol-2-ylidene)pyridine cobalt methyl complex, (iPrCNC)CoCH3, was evaluated for the catalytic hydrogenation of alkenes. At 22 °C and 4 atm of H2 pressure, (iPrCNC)CoCH3 is an effective pre-catalyst for the hydrogenation of sterically hindered, unactivated alkenes such as trans-methylstilbene, 1-methyl-1-cyclohexene and 2,3-dimethyl-2-butene, representing one of the most active cobalt hydrogenation catalysts reported to date. Preparation of the cobalt hydride complex, (iPrCNC)CoH was accomplished by hydrogenation of (iPrCNC)CoCH3. Over the course of 3 hours at 22 °C, migration of the metal-hydride to the 4-position of the pyridine ring yielded (4-H2-iPrCNC)CoN2. Similar alkyl migration was observed upon treatment of (iPrCNC)CoH with 1,1-diphenylethylene. This reactivity raised the question as to whether this class of chelate is redoxactive, engaging in radical chemistry with the cobalt center. A combination of structural, spectroscopic and computational studies was conducted and provided definitive evidence for bis(arylimidazol-2-ylidene)pyridine radicals in reduced cobalt chemistry. Spin density calculations established that the radicals were localized on the pyridine ring, accounting for the observed reactivity and suggest a wide family of pyridine-based pincers may also be redox active. PMID:23968297

  20. 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

  1. 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...

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. Manganese-Catalyzed Cross-Coupling of Aryl Halides and Grignard Reagents by a Radical Mechanism

    DEFF Research Database (Denmark)

    Antonacci, Giuseppe; Ahlburg, Andreas; Fristrup, Peter

    2017-01-01

    The substrate scope and the mechanism have been investigated for the MnCl2-catalyzed cross-coupling reaction between aryl halides and Grignard reagents. The transformation proceeds rapidly and in good yield when the aryl halide component is an aryl chloride containing a cyano or an ester group...... in the para position or a cyano group in the ortho position. A range of other substituents gave no conversion of the aryl halide or led to the formation of side products. A broader scope was observed for the Grignard reagents, where a variety of alkyl- and arylmagnesium chlorides participated in the coupling....... Two radical-clock experiments were carried out, and in both cases an intermediate aryl radical was successfully trapped. The cross-coupling reaction is therefore believed to proceed by an SRN1 mechanism, with a triorganomanganate complex serving as the most likely nucleophile and single-electron donor...

  7. On polynomial and multiplicative radicals | Tumurbat | Quaestiones ...

    African Journals Online (AJOL)

    We show that polynomial and multiplicative radicals in [1] are special cases of radicals defined by means of elements. We scrutinize the way of defining a radical γG by a subset G of polynomials in noncommuting indeterminates. Defining polynomial radicals, Drazin and Roberts [1] required that the set G be closed

  8. 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...

  9. 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

  10. 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

  11. 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.

  12. Catalyzed Radical Termination in the Presence of Tellanyl Radicals.

    Science.gov (United States)

    Ribelli, Thomas G; Rahaman, S M Wahidur; Matyjaszewski, Krzysztof; Poli, Rinaldo

    2017-10-09

    The decomposition of the diazo initiator dimethyl 2,2'-azobis(isobutyrate) (V-601), generating the Me 2 C . (CO 2 Me) radical, affords essentially the same fraction of disproportionation and combination in media with a large range of viscosity (C 6 D 6 , [D 6 ]DMSO, and PEG 200) in the 25-100 °C range. This is in stark contrast to recent results by Yamago et al. on the same radical generated from Me 2 C(TeMe)(CO 2 Me) and on other X-TeR systems (X=polymer chain or unimer model; R=Me, Ph). The discrepancy is rationalized on the basis of an unprecedented RTe . -catalyzed radical disproportionation, with support from DFT calculations and photochemicaL V-601 decomposition in the presence of Te 2 Ph 2 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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.

  19. Overexpression of metallothionein in CHO cells and its effect on cell killing by ionizing radiation and alkylating agents

    International Nuclear Information System (INIS)

    Lohrer, H.; Robson, T.

    1989-01-01

    Metallothionein protein protects cells from the toxic effects of heavy metal ions. To establish its protective function against ionizing radiation and alkylating agents, a model system was created by transfecting two CHO cell lines (wild-type, K1-2 and X-ray sensitive, xrs-2 subclone Bc11) with the human metallothionein II-A (hMTII-A) gene integrated in a bovine papilloma derived autonomously replicating vector. The isolated transfectants are cadmium-resistant (Cd 1 ), due to the overexpression of the hMTII-A gene. Their steady-state level of hMTII-A mRNA can be increased up to 40-fold after Cd treatment and 20-fold after induction with ionizing radiation. The transfected cell lines proved to be as sensitive as the recipient cell lines to ionizing radiation and bleomycin but the transfectants were significantly more resistant to N-methyl-nitro-nitrosoguanidine (MNNG) and mitomycin C (MMC). These results lead to the conclusion that the MT protein does provide a defence mechanism to protect cells from monofunctional alkylating and cross-linking agents but not from free radicals. (author)

  20. 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- ...

  1. 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.

  2. 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

  3. 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.

  4. 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 ...

  5. 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...

  6. 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.

  7. 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.

  8. 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…

  9. 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.

  10. 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.

  11. 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 ...

  12. 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

  13. 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.

  14. 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.)

  15. Epistemological barriers to radical behaviorism.

    Science.gov (United States)

    O'Donohue, W T; Callaghan, G M; Ruckstuhl, L E

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers.

  16. Laparoscopic radical prostatectomy: a review

    Directory of Open Access Journals (Sweden)

    Pierluigi Bove

    2009-04-01

    Full Text Available INTRODUCTION: We offer an overview of the intra-, peri- and postoperative outcomes of laparoscopic radical prostatectomy (LRP with the endpoint to evaluate potential advantages of this approach. MATERIAL AND METHODS: We conducted an extensive Medline literature search (search terms “laparoscopic radical prostatectomy” and “radical prostatectomy” from 1990 until 2007. Only full-length English language articles identified during this search were considered for this analysis. A preference was given to the articles with large series with more than 100 patients. All pertinent articles concerning localized prostate cancer were reviewed. CONCLUSION:Pure LRP has shown to be feasible and reproducible but it is difficult to learn. Potential advantages over open surgery have to be confirmed by longer-term follow-up and adequately designed clinical studies.

  17. Epistemological barriers to radical behaviorism

    Science.gov (United States)

    O'Donohue, William T.; Callaghan, Glenn M.; Ruckstuhl, L. E.

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers. PMID:22478314

  18. 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.

  19. Alcohols as alkylating agents in heteroarene C?H functionalization

    OpenAIRE

    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 damage 1 . 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 underutilize...

  20. 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.

  1. Radical democratic politics and feminism

    Directory of Open Access Journals (Sweden)

    Martínez Labrin, Soledad

    2006-05-01

    Full Text Available In the article I present a reflection around the radical democratic project proposed by Chantal Mouffe and Ernesto Laclau. Specifically, I examine the application of the project in the context of the “new social movements” and especially, of feminist movement. I state the need of drawing attention to universalism and essentialism as the main obstacles to generate a collective proposal without margins. Nevertheless, doubts remind about the possibility of building up a feminism tailored by the radical democratic project, in a stage in which the political action of such a movement is characterized by categories that are closed and crystallized

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Radicalization and Radical Catalysis of Biomass Sugars: Insights from First-principles Studies

    OpenAIRE

    Yang, Gang; Zhu, Chang; Zou, Xianli; Zhou, Lijun

    2016-01-01

    Ab initio and density functional calculations are conducted to investigate the radicalization processes and radical catalysis of biomass sugars. Structural alterations due to radicalization generally focus on the radicalized sites, and radicalization affects H-bonds in D-fructofuranose more than in D-glucopyranose, potentially with outcome of new H-bonds. Performances of different functionals and basis sets are evaluated for all radicalization processes, and enthalpy changes and Gibbs free en...

  8. 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.

  9. 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.

  10. Toluene combustion: reaction paths, thermochemical properties, and kinetic analysis for the methylphenyl radical + O2 reaction.

    Science.gov (United States)

    da Silva, Gabriel; Chen, Chiung-Chu; Bozzelli, Joseph W

    2007-09-06

    Aromatic compounds such as toluene and xylene are major components of many fuels. Accurate kinetic mechanisms for the combustion of toluene are, however, incomplete, as they do not accurately model experimental results such as strain rates and ignition times and consistently underpredict conversion. Current kinetic mechanisms for toluene combustion neglect the reactions of the methylphenyl radicals, and we believe that this is responsible, in part, for the shortcomings of these models. We also demonstrate how methylphenyl radical formation is important in the combustion and pyrolysis of other alkyl-substituted aromatic compounds such as xylene and trimethylbenzene. We have studied the oxidation reactions of the methylphenyl radicals with O2 using computational ab initio and density functional theory methods. A detailed reaction submechanism is presented for the 2-methylphenyl radical + O2 system, with 16 intermediates and products. For each species, enthalpies of formation are calculated using the computational methods G3 and G3B3, with isodesmic work reactions used to minimize computational errors. Transition states are calculated at the G3B3 level, yielding high-pressure limit elementary rate constants as a function of temperature. For the barrierless methylphenyl + O2 and methylphenoxy + O association reactions, rate constants are determined from variational transition state theory. Multichannel, multifrequency quantum Rice-Ramsperger-Kassel (qRRK) theory, with master equation analysis for falloff, provides rate constants as a function of temperature and pressure from 800 to 2400 K and 1 x 10(-4) to 1 x 10(3) atm. Analysis of our results shows that the dominant pathways for reaction of the three isomeric methylphenyl radicals is formation of methyloxepinoxy radicals and subsequent ring opening to methyl-dioxo-hexadienyl radicals. The next most important reaction pathway involves formation of methylphenoxy radicals + O in a chain branching process. At lower

  11. Reaction between protein radicals and other biomolecules

    DEFF Research Database (Denmark)

    Østdal, Henrik; Davies, Michael Jonathan; Andersen, Henrik J

    2002-01-01

    The present study investigates the reactivity of bovine serum albumin (BSA) radicals towards different biomolecules (urate, linoleic acid, and a polypeptide, poly(Glu-Ala-Tyr)). The BSA radical was formed at room temperature through a direct protein-to-protein radical transfer from H(2)O(2....... Subsequent analysis showed a decrease in the concentration of urate upon reaction with the BSA radical, while the BSA radical in the presence of poly(Glu-Ala-Tyr) resulted in increased formation of the characteristic protein oxidation product, dityrosine. Reaction between the BSA radical and a linoleic acid...

  12. Students' Ideas and Radical Constructivism

    Science.gov (United States)

    Sánchez Gómez, Pedro J.

    2016-01-01

    In this article, I study, from the point of view of the analytic philosophy of mind, the compatibility of students' ideas studies (SIS) with radical constructivism (RC). I demonstrate that RC is based on a psychology of "narrow mental states"; that is, the idea that the mental content of an individual can be fully characterised without…

  13. [Reprodcutive results of radical trachelectomy].

    Science.gov (United States)

    Martínez-Chapa, Arnulfo; Alonso-Reyes, Nelly; Luna-Macías, Miguel

    2015-12-01

    Historically, cervical cancer in early stages has been treated with radical hysterectomy and radiotherapy with no option in keeping the uterine-ovarian function. Since two decades ago, evidence shows these cases are candidates for radical trachelectomy, a procedure capable of preserving the fertility without affecting the oncological outcome. To analyze reproductive results among patients treated with radical trachelectomy, in a reference center from the northeast of Mexico. Between March 1999 and December 2013, 27 cases with cervical cancer in early stages were treated with vaginal or abdominal radical trachelectomy in the ISSSTE Regional Hospital in Monterrey, NL (Mexico). We obtained the gynecological, medical and surgical clinical history. Plan of analysis consisted of descriptive statistics. Age range was 27-39 years. Main complications were cervical stenosis (n=1) and erosion of cerclaje (n=2). Eighteen patients tried to get pregnant, 8 of them got a spontaneous pregnancy; 1 more patient required assisted reproduction technics and did not succeed. All pregnancies were delivered by cesarean section and were preterm births; 3 underwent premature rupture of membranes. Two pregnancies ended in abortion, one at 10 weeks with severe hemorrhage that needed hysterectomy; the second one, at 1 7 weeks, received a fine uterine curettage. Only 6 cases (33%) got a live birth. Only one third of the attempted pregnancies got a live birth. Assisted reproduction technics play an important role and should be offer to all cases. Cerclaje is an important factor to carry a pregnancy up to the third trimester.

  14. Exploring the Theories of Radicalization

    Directory of Open Access Journals (Sweden)

    Maskaliūnaitė Asta

    2015-12-01

    Full Text Available After the London bombings in July 2005, the concern of terrorism scholars and policy makers has turned to “home-grown” terrorism and potential for political violence from within the states. “Radicalization” became a new buzz word. This article follows a number of reviews of the literature on radicalization and offers another angle for looking at this research. First, it discusses the term “radicalization” and suggests the use of the following definition of radicalization as a process by which a person adopts belief systems which justify the use of violence to effect social change and comes to actively support as well as employ violent means for political purposes. Next, it proposes to see the theories of radicalization focusing on the individual and the two dimensions of his/her motivation: whether that motivation is internal or external and whether it is due to personal choice or either internal (due to some psychological traits or external compulsion. Though not all theories fall neatly within these categories, they make it possible to make comparisons of contributions from a variety of different areas thus reflecting on the interdisciplinary nature of the study of terrorism in general and radicalization as a part of it.

  15. Remembering Dutch-Moluccan radicalism

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2016-01-01

    This article examines memory politics in relation to radical actions of young Dutch-Moluccans, more specifically a train hijacking in 1977 at the village of De Punt in the Netherlands. The article examines how these historical events were remembered in the drama-documentary television film, De Punt...

  16. Is Radical Innovation Management Misunderstood?

    DEFF Research Database (Denmark)

    Kristiansen, Jimmi Normann; Gertsen, Frank

    2015-01-01

    This paper poses a critical view on radical innovation (RI) management research and practice. The study investigates how expected RI performance influences firms’ under- standing of their RI capability. RI performance is often based on output measures such as market shares or fiscal return...

  17. Radical scavenging properties of genistein.

    Science.gov (United States)

    Zielonka, Jacek; Gebicki, Jerzy; Grynkiewicz, Grzegorz

    2003-10-15

    The reactivity of genistein toward reactive radical species has been investigated by means of pulse radiolysis. The values of rate constants, respectively 2.3 x 10(10) M(-1)s(-1) and 1.3 x 10(10) M(-1)s(-1) for the reaction with hydroxyl radical at pH 8.3 and 3.0, are close to diffusion limit indicating that genistein is a potent hydroxyl radical scavenger. The reactivity of genistein towards one-electron oxidants has also been investigated. The rate constants k = 4.6 x 10(9) M(-1)s(-1) (pH 8.3) and 6.7 x 10(8) M(-1)s(-1) (pH 7.6) have been determined for the reaction of genistein with *N3 and Br2*- radicals, respectively. For both oxidants the rate constants at pH 3 does not exceed 10(8) M(-1)s(-1). The differences in reactivity of genistein towards the oxidants at different acidity of the solution have been assumed to arise from the acid-base equilibria of genistein. The dissociation constants for genistein (pKa: 7.2, 10.0, and 13.1) have been evaluated spectroscopically. The influence of acid-base equilibria on bond dissociation energy and ionization potential for genistein has also been investigated by means of DFT calculations. It has been concluded on the basis of these calculations that monoanionic form of genistein existing at physiological pH is more powerful radical scavenger than the neutral molecule.

  18. 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....

  19. 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).

  20. Flavonoids as scavengers of nitric oxide radical.

    NARCIS (Netherlands)

    van Acker, S.A.B.E.; Tromp, M.N.J.L.; Haenen, G.R.M.M.; van der Vijgh, W.J.F.; Bast, A.

    1995-01-01

    Flavonoids are a group of naturally occurring compounds used, e.g., in the treatment of vascular endothelial damage. They are known to be excellent scavengers of oxygen free radicals. Since the nitric oxide radical (

  1. Reaction between protein radicals and other biomolecules

    DEFF Research Database (Denmark)

    Østdal, Henrik; Davies, Michael Jonathan; Andersen, Henrik J

    2002-01-01

    The present study investigates the reactivity of bovine serum albumin (BSA) radicals towards different biomolecules (urate, linoleic acid, and a polypeptide, poly(Glu-Ala-Tyr)). The BSA radical was formed at room temperature through a direct protein-to-protein radical transfer from H(2)O(2......)-activated immobilized horseradish peroxidase (im-HRP). Subsequently, each of the three different biomolecules was separately added to the BSA radicals, after removal of im-HRP by centrifugation. Electron spin resonance (ESR) spectroscopy showed that all three biomolecules quenched the BSA radicals....... Subsequent analysis showed a decrease in the concentration of urate upon reaction with the BSA radical, while the BSA radical in the presence of poly(Glu-Ala-Tyr) resulted in increased formation of the characteristic protein oxidation product, dityrosine. Reaction between the BSA radical and a linoleic acid...

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  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. 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.

  11. Oxygen free radicals in rheumatoid arthritis

    NARCIS (Netherlands)

    P. Biemond (Pieter)

    1986-01-01

    textabstractCurrent knowledge strongly suggests that oxygen free radicals are involved in the pathogenesis of RA. Additional information about the mechanism of free radical attack is necessary in order to find out if interaction with the mechanism of free radical damage can be used in the treatment

  12. 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. ...

  13. 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 ...

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Geoscientists and the Radical Middle

    Science.gov (United States)

    Tinker, S. W.

    2015-12-01

    Addressing the great challenges facing society requires industry, government, and academia to work together. I call this overlap space, where compromises are made and real solutions determined, the Radical Middle. Radical because it can appear at times as if the loudest and most publicly influential voices lie outside of the actual solution space, content to provoke but not problem-solve. One key area where geoscientists can play a lead role in the Radical Middle is in the overlap between energy, the environment, and the economy. Globally, fossil fuels still represent 85% of the aggregate energy mix. As existing conventional oil and natural-gas reservoir production continues to slowly decline, unconventional reservoirs, led today by shale and other more expensive resources, will represent a growing part of the oil and gas production mix. Many of these unconventional reservoirs require hydraulic fracturing. The positive economic impact of hydraulic fracturing and associated natural gas and oil production on the United States economy is well documented and undeniable. Yet there are environmental concerns about fracking, and some states and nations have imposed moratoria. This energy-environment-economy space is ideal for leadership from the geosciences. Another such overlap space is the potential for geoscience leadership in relations with China, whose economy and global presence continue to expand. Although China is building major hydropower and natural-gas power plants, as well as nuclear reactors, coal is still king—with the associated environmental impacts. Carbon sequestration—onshore in brine and to enhance oil recovery, as well as offshore—could prove viable. It is vital that educated and objective geoscientists from industry, government, and academia leave their corners and work together in the Radical Middle to educate the public and develop and deliver balanced, economically sensible energy and environmental strategies.

  3. Free radical mediated cellulose degradation

    OpenAIRE

    Johansson, Erik

    2003-01-01

    This thesis addresses the mechanisms involved in cellulosedegradation in general and Totally Chlorine Free (TCF) bleachingof pulp in particular. The thesis shows that the cellulosedegradation during high consistency ozone bleaching is explainedby free radical chain reactions. By simulation, it has been shown that the number, weight andviscosity average of liner polymer chain length can be used tocalculate the number of random scissions in a linear polymer ofany molecular weight distribution, ...

  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. Remediation of polluted soils contaminated with Linear Alkyl Benzenes using Fenton's reagent

    Directory of Open Access Journals (Sweden)

    Douglas do Nascimento Silva

    2005-06-01

    Full Text Available Linear Alkyl Benzenes (LABs are used as insulating oil for electric cables. When it happens a spill, LABs they are basically sorbed in the soil, because, these compounds have high hidrophobicity and low vapor pressure. The conventional methods of treatment of soils are not efficient. The Fenton's reaction (reaction between a solution of iron II and hydrogen peroxide it generates hydroxyl radicals, not selective, and capable of oxidize a great variety of organic compounds. A study was conducted to evaluate the viability of use of the Fenton's reagents to promote the remediation of polluted soils with Linear Alkyl Benzenes. A column was especially projected for these experiments, packed with a sandy and other soil loamy. The pH of the soil was not altered. The obtained results demonstrated the technical viability of the process of injection of the Fenton's reagents for the treatment of polluted areas with LABs.Os Linear Alquilbenzenos (LABs são usados como fluido refrigerante de cabos elétricos. Quando ocorre um vazamento, os LABs ficam basicamente adsorvidos no solo, pois, são compostos bastante hidrofóbicos e com baixa pressão de vapor. Os métodos convencionais de tratamento de solos não são eficientes. A reação de Fenton (solução de ferro II e peróxido de hidrogênio gera radicais hidroxila, não seletivos, e capazes de oxidar uma grande variedade de compostos orgânicos, chegando a mineralização dos mesmos. Neste trabalho foi estudada a viabilidade de utilização dos reagentes de Fenton para promover a remediação de solos contaminados com LABs. Utilizou-se uma coluna especialmente projetada para estes experimentos, empacotada com um solo arenoso e outro argiloso. O pH do solo não foi alterado. Os resultados obtidos demonstram a viabilidade técnica do processo de injeção dos reagentes de Fenton para o tratamento de áreas contaminadas com LABs.

  6. Understanding ozone formation and the radical budget during oil sands plume transport in the Athabasca region of Alberta

    Science.gov (United States)

    Moussa, S. G.; Leithead, A.; Li, S. M.; Wang, D. K.; O'brien, J.; Mittermeier, R. L.; Gordon, M.; Staebler, R. M.; Liu, P.; Liggio, J.

    2015-12-01

    The sources of ozone and hydroxyl radicals (OH) in the Alberta oil sands (OS) region have not previously been well characterized. In the summer of 2013, airborne measurements of various volatile organic compounds (VOCs), nitrogen oxides (NOx = NO2+NO) and ozone were made in the Athabasca OS region between August 13 and September 7, 2013. Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) and whole air samples were used to measure VOCs. A box model incorporating the Master Chemical Mechanism (MCM v3.3), was constrained by measured chemical species and meteorological parameters and used to simulate the evolution of an OS plume. In doing so, an improved understanding of the chemical factors controlling the radical budget and the evolution of ozone in oil sands plumes is achieved. Our results indicate that approximately 20% of the in-plume generated OH radicals are derived from primary sources (HCHO, O3 and HONO photolysis). The remaining OH is derived from the recycling of hydroperoxyl radical (HO2). The HO2 and alkyl peroxyl radical (RO2) chemistry leads to 35% of the ozone formation in the plume, while the main sink for ozone in the plume was via reactions with alkenes (anthropogenic and biogenic). The results of this work will help to characterize ozone formation and the factors influencing its atmospheric fate in the oil sands region.

  7. 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...

  8. 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

  9. 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.

  10. Oxidative stress, free radicals and protein peroxides.

    Science.gov (United States)

    Gebicki, Janusz M

    2016-04-01

    Primary free radicals generated under oxidative stress in cells and tissues produce a cascade of reactive secondary radicals, which attack biomolecules with efficiency determined by the reaction rate constants and target concentration. Proteins are prominent targets because they constitute the bulk of the organic content of cells and tissues and react readily with many of the secondary radicals. The reactions commonly lead to the formation of carbon-centered radicals, which generally convert in vivo to peroxyl radicals and finally to semistable hydroperoxides. All of these intermediates can initiate biological damage. This article outlines the advantages of the application of ionizing radiations to studies of radicals, with particular reference to the generation of desired radicals, studies of the kinetics of their reactions and correlating the results with events in biological systems. In one such application, formation of protein hydroperoxides in irradiated cells was inhibited by the intracellular ascorbate and glutathione. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Youth De-Radicalization: A Canadian Framework

    Directory of Open Access Journals (Sweden)

    Hafal (Haval Ahmad

    2017-09-01

    Full Text Available Youth radicalization leading to violence has become a growing fear among Canadians, as terrorist attacks are carried out in Western states. Although Canada has suffered relatively fewer acts of violence, this fear has intensified and a de-radicalization strategy is needed in the Canadian context. In a qualitative case study methodology, interviews were conducted with school counsellors, religious leaders, and academics to explore solutions to youth radicalization. Youth de-radicalization approaches from the United Kingdom were analyzed and found that community-based initiatives were missing from programming. Social identity theory is used to explain that youth join radicalized groups to feel a sense of belonging and have to be provided an alternative and moderate group identity to de-radicalize. This study found youth de-radicalization in Canada is best served through a community collaboration approach.

  12. 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

  13. 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.

  14. 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...

  15. 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

  16. 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.

  17. 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.

  18. 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 ...

  19. 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...

  20. 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...

  1. Effect of some free radicals on superoxide dismutase and ...

    African Journals Online (AJOL)

    Free radicals are species with unpaired electron in their outermost shell. Most free radicals come from oxygen or nitrogen atoms. Radical species such as superoxide radical, hydroxyl radicals and hydrated electron are called the primary radicals of water radiolysis and can be produced by irradiating water molecule.

  2. 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.

  3. 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...

  4. Online radicalization: the net or the netizen?

    Directory of Open Access Journals (Sweden)

    Femi Richard Omotoyinbo

    2014-10-01

    Full Text Available Purpose - Radicalization has gained some unusual prominence in the academic circles; maintaining a generic existence not only in the political sector. And with the advent of the Information Communication Technology (ICT, radicalization has begun to have some virtual dimension even in the remotest of human communities. This study seeks to mobilize a universal awareness on the collective urgency to oppose Online Radicalization (a radicalization that happens through the internet due to its propensity to engendering conflicts. It also aims at identifying the principal cause of online radicalization and steer a clear course for a practical reversal in the systems of online radicalization.Design/methodology/approach - The study is divided into three primary parts. The general notion of radicalization is the focus of the first part; which is further analysed into the levels of online radicalization with its accompanying developments and segments. The second part utilizes analytic and historical method to pinpoint the principal cause of online radicalization amidst the suspected causal factors (the Net and the Netizen. The final part analytically focuses on the Netizen (a user/citizen of the internet as the primary cause of online radicalization, and how the global community can bring about a corresponding change in the Net by the application of some measures on the Netizen.Findings - By virtue of the analytic plus historical methods employed by this study; it was initially identified that radicalization is basically having two versions which are online and offline. Further emphasis on the online version reveals that its existence is only made possible by the availability of the internet (the Net. Since the Net is a global phenomenon online radicalization is considered to be worldwide: a menace of globalization. However, the study later indicated that the Net is a facilitator and a cause of online radicalization. A view was deduced that the Netizen is

  5. Iron and iron derived radicals

    International Nuclear Information System (INIS)

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fast! Think small! In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab

  6. Laser spectroscopy of hydrocarbon radicals

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P. [Harvard Univ., Cambridge, MA (United States)

    1993-12-01

    The author reports the application of supersonic jet flash pyrolysis to the specific preparation of a range of organic radicals, biradicals, and carbenes in a skimmed molecular beam. Each species was produced cleanly and specifically, with little or no secondary reactions by the thermal dissociation of appropriately designed and synthesized organic precursors. Photoelectron spectra of the three isomeric C{sub 3}H{sub 2} carbenes, ortho-benzyne, and the {alpha},3-dehydrotoluene biradical, were used to establish adiabatic ionization potentials for use in thermochemical determinations.

  7. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

    1993-12-01

    The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

  8. Free radical kinetics of irradiated durum wheat

    International Nuclear Information System (INIS)

    Korkmaz, M.; Polat, M.

    2000-01-01

    In the present work, a detailed ESR investigation of characteristic features and kinetic behaviors at three different temperatures of free radicals produced in a species of durum wheat cultivated in Turkey and irradiated at doses of up to 5 kGy by a γ source, is reported. Unirradiated wheat samples exhibit a weak, single-line ESR signal originating from a radical of unknown structure called radical III in this work. Irradiation produces two more radicals identified as hydroxyalkyl (I) and aldehydalkyl (II) radicals beside radical III. The radicals (I, II and III) follow complicated kinetics. Species I and II initially decay very fast after the irradiation followed by slower decay. Radical half-life times depend on whether they were induced in the crystalline or amorphous fractions of the wheat starch. Activation energy values of the radicals were found to follow the order E a (III)>E a (II)>E a (I). ESR parameters of the radical species were determined by simulating experimental spectra recorded following the irradiation. Room temperature dose-response curves and variations of different spectral parameters between 120 and 390 K were also studied

  9. Free radical kinetics of irradiated durum wheat

    Energy Technology Data Exchange (ETDEWEB)

    Korkmaz, M.; Polat, M

    2000-04-01

    In the present work, a detailed ESR investigation of characteristic features and kinetic behaviors at three different temperatures of free radicals produced in a species of durum wheat cultivated in Turkey and irradiated at doses of up to 5 kGy by a {gamma} source, is reported. Unirradiated wheat samples exhibit a weak, single-line ESR signal originating from a radical of unknown structure called radical III in this work. Irradiation produces two more radicals identified as hydroxyalkyl (I) and aldehydalkyl (II) radicals beside radical III. The radicals (I, II and III) follow complicated kinetics. Species I and II initially decay very fast after the irradiation followed by slower decay. Radical half-life times depend on whether they were induced in the crystalline or amorphous fractions of the wheat starch. Activation energy values of the radicals were found to follow the order E{sub a}(III)>E{sub a}(II)>E{sub a}(I). ESR parameters of the radical species were determined by simulating experimental spectra recorded following the irradiation. Room temperature dose-response curves and variations of different spectral parameters between 120 and 390 K were also studied.

  10. Radical constructivism: Between realism and solipsism

    Science.gov (United States)

    Martínez-Delgado, Alberto

    2002-11-01

    This paper criticizes radical constructivism of the Glasersfeld type, pointing out some contradictions between the declared radical principles and their theoretical and practical development. These contradictions manifest themselves in a frequent oscillation between solipsism and realism, despite constructivist claims to be an anti-realist theory. The paper also points out the contradiction between the relativism of the radical constructivist principles and the constructivist exclusion of other epistemological or educational paradigms. It also disputes the originality and importance of the radical constructivist paradigm, suggesting the idea of an isomorphism between radical constructivist theory and contemplative realism. In addition, some pedagogical and scientific methodological aspects of the radical constructivist model are examined. Although radical constructivism claims to be a rational theory and advocates deductive thinking, it is argued that there is no logical deductive connection between the radical principles of constructivism and the radical constructivist ideas about scientific research and learning. The paper suggests the possibility of an ideological substratum in the construction and hegemonic success of subjective constructivism and, finally, briefly advances an alternative realist model to epistemological and educational radical constructivism.

  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. 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.

  13. 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.

  14. 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)

  15. 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.

  16. Patterned monolayers of nitronyl nitroxide radicals

    NARCIS (Netherlands)

    Mannini, Matteo; Rovai, Donella; Sorace, Lorenzo; Perl, A.; Ravoo, B.J.; Reinhoudt, David

    2008-01-01

    We report here the results of the preliminary characterization of the monolayer obtained both by self-assembling and microcontact printing of a di-alkyl sulfide nitronyl nitroxide derivative, 11-decyl sulfanyl-undecanyl nitronyl nitroxide of which we describe the synthesis. The sulfide unit has been

  17. 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.

  18. Radicalization In Pakistan And The Spread Of Radical Islam In Pakistan

    Directory of Open Access Journals (Sweden)

    Bahir ahmad

    2015-08-01

    Full Text Available ABSTRACT It is pertinent to mention that radicalism is not intrinsic to Islam and radical interpretations of the religion or for that matter may occur within any way of life and religion Saikal 2003 and yet the question remains as to why Muslims in certain geographical regions have more radical approaches towards their religion and also that what are the causes of such radicalization. Becoming a radical Muslim is not even a matter of a day nor is it a sudden process. There are several reasons behind making a person radical peaceful angry smiling or tolerant. For knowing the reason behind radicalization or radicals persons one has to understand the causes. Tracing these causes is one of the ways to eliminate such behavior. The first step in the elimination of the radical sentiments in a person is to develop peace in his personality Fair Malhotra amp Shapiro 2010. The chapter which has been addressed here is going to shed light on the roots and symptoms of the radicalism. There will be a brief discussion on how the roots of radicalism can be traced and can be eliminated. The assessment and discussion will be conducted on the parameters of the economy media politics and theology from social cultural point of view. According to the analysis of Ahrari 2000 political factor is one of the major and direct factors which have resulted in causing of the radicalism. These factors however intertwine with one another. Radical actions cannot take place only because of the political factors.

  19. Western Radicalization: Rethinking the Psychology of Terrorism

    Science.gov (United States)

    2017-03-01

    RADICALIZATION: RETHINKING THE PSYCHOLOGY OF TERRORISM by Vern Pierson March 2017 Thesis Co-Advisors: Mohammed Hafez John Rollins THIS PAGE...thesis 4. TITLE AND SUBTITLE WESTERN RADICALIZATION: RETHINKING THE PSYCHOLOGY OF TERRORISM 5. FUNDING NUMBERS 6. AUTHOR(S) Vern Pierson 7...terrorists are engaging in political “group speak” and are by nature psychologically “normal.” Thus, anyone is susceptible to radicalization. To counter

  20. Poly(n-isopropylacrylamide)-based hydrogel coatings on magnetite nanoparticles via atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Frimpong, Reynolds A; Hilt, J Zach [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States)], E-mail: hilt@engr.uky.edu

    2008-04-30

    Core magnetite (Fe{sub 3}O{sub 4}) nanoparticles have been functionalized with a model intelligent hydrogel system based on the temperature responsive polymer poly(n-isopropyl acrylamide) (PNIPAAm) to obtain magnetically responsive core-shell nanocomposites. Fe{sub 3}O{sub 4} nanoparticles were obtained from a one-pot co-precipitation method which provided either oleic acid (hydrophobic) or citric acid (hydrophilic) coated nanoparticles. Subsequent ligand exchange of these coatings with various bromine alkyl halides and a bromo silane provided initiating sites for functionalization with NIPAAm using atom transfer radical polymerization (ATRP). The bromine alkyl halides that were used were 2-bromo-2-methyl propionic acid (BMPA) and 2-bromopropionyl bromide (BPB). The bromo silane that was used was 3-bromopropyl trimethoxysilane (BPTS). The intelligent polymeric shell consists of NIPAAm crosslinked with poly(ethylene glycol) 400 dimethacrylate (PEG400DMA). Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) were used to confirm the presence of the polymeric shell. Dynamic light scattering (DLS) was used to characterize the nanocomposites for particle size changes with temperature. Their magnetic and temperature responsiveness show great promise for further biomedical applications. This platform for functionalizing magnetic nanoparticles with intelligent hydrogels promises to impact a wide range of medical and biological applications of magnetic nanoparticles.

  1. Poly(n-isopropylacrylamide)-based hydrogel coatings on magnetite nanoparticles via atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Frimpong, Reynolds A; Hilt, J Zach

    2008-01-01

    Core magnetite (Fe 3 O 4 ) nanoparticles have been functionalized with a model intelligent hydrogel system based on the temperature responsive polymer poly(n-isopropyl acrylamide) (PNIPAAm) to obtain magnetically responsive core-shell nanocomposites. Fe 3 O 4 nanoparticles were obtained from a one-pot co-precipitation method which provided either oleic acid (hydrophobic) or citric acid (hydrophilic) coated nanoparticles. Subsequent ligand exchange of these coatings with various bromine alkyl halides and a bromo silane provided initiating sites for functionalization with NIPAAm using atom transfer radical polymerization (ATRP). The bromine alkyl halides that were used were 2-bromo-2-methyl propionic acid (BMPA) and 2-bromopropionyl bromide (BPB). The bromo silane that was used was 3-bromopropyl trimethoxysilane (BPTS). The intelligent polymeric shell consists of NIPAAm crosslinked with poly(ethylene glycol) 400 dimethacrylate (PEG400DMA). Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) were used to confirm the presence of the polymeric shell. Dynamic light scattering (DLS) was used to characterize the nanocomposites for particle size changes with temperature. Their magnetic and temperature responsiveness show great promise for further biomedical applications. This platform for functionalizing magnetic nanoparticles with intelligent hydrogels promises to impact a wide range of medical and biological applications of magnetic nanoparticles

  2. Dynamics of Radical-Mediated Enzyme Catalyses

    Science.gov (United States)

    Warncke, Kurt

    1997-11-01

    An emergent class of enzymes harnesses the extreme reactivity of electron-deficient free radical species to perform some of the most difficult reactions in biology. The regio- and stereo-selectivity achieved by these enzymes defies long-held ideas that radical reactions are non-specific. The common primary step in these catalyses is metal- or metallocenter-assisted generation of an electron-deficient organic "initiator radical". The initiator radical abstracts a hydrogen atom from the substrate, opening a new reaction channel for rearrangement to the product. Our aim is to elucidate the detailed molecular mechanisms of the radical pair separation and radical rearrangement steps. Radical pair separation and substrate radical rearrangement are tracked by using time-resolved (10-7 to 10-3 s) techniques of pulsed-electron paramagnetic resonance spectroscopy (FT-EPR, ESEEM). Synchronous time-evolution of the reactions is attained by triggering with a visible laser pulse. Transient non-Boltzmann population of the states of the spin-coupled systems, and resultant electron spin polarization, facilitates study at or near room temperature under conditions where the enzymes are operative. The systems examined include ethanolamine deaminase, a vitamin B12 coenzyme-dependent enzyme, ribonucleotide reductase and photosynthetic reaction centers. The electronic and nuclear structural and kinetic information obtained from the pulsed-EPR studies is used to address how the initiator radicals are stabilized against deleterious recombination with the metal, and to distinguish the participation of concerted versus sequential rearrangement pathways.

  3. Organosilicon Radicals with Si-H and Si-Me Bonds from Commodity Precursors.

    Science.gov (United States)

    Kundu, Subrata; Samuel, Prinson P; Sinhababu, Soumen; Luebben, Anna V; Dittrich, Birger; Andrada, Diego M; Frenking, Gernot; Stückl, A Claudia; Schwederski, Brigitte; Paretzki, Alexa; Kaim, Wolfgang; Roesky, Herbert W

    2017-08-16

    The cyclic alkyl(amino) carbene (cAAC) stabilized biradicals of composition (cAAC) 2 SiH 2 (1), (cAAC)SiMe 2 -SiMe 2 (cAAC) (2), and (cAAC)SiMeCl-SiMeCl(cAAC) (3) have been isolated as molecular species. All the compounds are stable at room temperature for more than 6 months under inert conditions in the solid state. All radical species were fully characterized by single-crystal X-ray structure analysis and EPR spectroscopy. Furthermore, the structure and bonding of compounds 1-3 have been investigated by theoretical methods. Compound 1 contains the SiH 2 moiety and this is the first instance, where we have isolated 1 without an acceptor molecule.

  4. Synthesis and characterization of functional copolymer/organo-silicate nanoarchitectures through interlamellar complex-radical (coterpolymerization

    Directory of Open Access Journals (Sweden)

    2008-09-01

    Full Text Available The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized by interlamellar complex-radical (coterpolymerization of intercalated monomer complexes of maleic anhydride (MA and itaconic acid (IA with dimethyl dodecylamine surface modified montmorillonite (organo-MMT (MA…DMDA-MMT and IA…DMDA-MMT n-butyl methacrylate (BMA and/or BMA/styrene monomer mixtures. The results of nanocomposite structure–composition– property relationship studies indicate that interlamellar complex-formation between anhydride/acid units and surface alkyl amine and rigid/flexible linkage balance in polymer chains are important factors providing the effective intercalation/ exfoliation of the polymer chains into the silicate galleries, the formation of nanostructural hybrids with higher thermal stability, dynamic mechanical behaviour and well dispersed morphology.

  5. Insertion of molecular oxygen into a palladium(II) methyl bond: a radical chain mechanism involving palladium(III) intermediates.

    Science.gov (United States)

    Boisvert, Luc; Denney, Melanie C; Hanson, Susan Kloek; Goldberg, Karen I

    2009-11-04

    The reaction of (bipy)PdMe(2) (1) (bipy = 2,2'-bipyridine) with molecular oxygen results in the formation of the palladium(II) methylperoxide complex (bipy)PdMe(OOMe) (2). The identity of the product 2 has been confirmed by independent synthesis. Results of kinetic studies of this unprecedented oxygen insertion reaction into a palladium alkyl bond support the involvement of a radical chain mechanism. Reproducible rates, attained in the presence of the radical initiator 2,2'-azobis(2-methylpropionitrile) (AIBN), reveal that the reaction is overall first-order (one-half-order in both [1] and [AIBN], and zero-order in [O(2)]). The unusual rate law (half-order in [1]) implies that the reaction proceeds by a mechanism that differs significantly from those for organic autoxidations and for the recently reported examples of insertion of O(2) into Pd(II) hydride bonds. The mechanism for the autoxidation of 1 is more closely related to that found for the autoxidation of main group and early transition metal alkyl complexes. Notably, the chain propagation is proposed to proceed via a stepwise associative homolytic substitution at the Pd center of 1 with formation of a pentacoordinate Pd(III) intermediate.

  6. 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

  7. 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 ...

  8. 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)

  9. 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)

  10. 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...

  11. 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

  12. 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.

  13. 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

  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; 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.

  15. 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.

  16. 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...

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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.

  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. 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.

  8. "Cartooning capitalism": Radical cartooning and the making of American popular radicalism in the early twentieth century

    OpenAIRE

    Cohen, Michael

    2007-01-01

    During the first two decades of the twentieth century, a mass culture of popular radicalism - consisting of various socialist, industrial unionist, anarchist, Progressive, feminist, black radical and other movements - arose to challenge the legitimacy of corporate capitalism in the United States. This article considers the role of radical cartoonists in propagandizing for, and forging unity within, this culture of popular radicalism. By articulating a common set of anti-capitalist values and ...

  9. Students' Ideas and Radical Constructivism

    Science.gov (United States)

    Sánchez Gómez, Pedro J.

    2016-08-01

    In this article, I study, from the point of view of the analytic philosophy of mind, the compatibility of students' ideas studies (SIS) with radical constructivism (RC). I demonstrate that RC is based on a psychology of narrow mental states; that is, the idea that the mental content of an individual can be fully characterised without any reference external to her or him. I show that this fact imposes some severe restrictions to SIS to be incorporated into RC. In particular, I argue that only qualitative studies can comply with the requirement of narrowness. Nevertheless, I propose that quantitative works can be employed as sources of types in order to study token actual students. I use this type-token dichotomy to put forward an outline of a theory of the relation between school contents and mental contents. In this view, token mental contents regarding a given topic can be defined, and probed, only by resorting to typical school contents.

  10. Iron and iron derived radicals

    Energy Technology Data Exchange (ETDEWEB)

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fastexclamation Think smallexclamation In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab.

  11. Kierkegaard as radical Christian thinker

    Directory of Open Access Journals (Sweden)

    Mojsić Sofija

    2013-01-01

    Full Text Available The main goal of this paper is the reaffirmation and emphasis of the radical, revolutionary aspect of Kierkegaard’s thought which has been mainly neglected in the standard literature on the Danish thinker. The author contends that there were two crises in Kierkegaard’s life: in 1838 and 1848. In 1838 Kierkegaard completely withdrew from the world and people into his “hidden inwardness”, which he claimed to be the essence of true Christianity. In 1848 he broke through his isolation and spoke openly of his new conviction. He stressed the practical and revolutionary character of Christianity, which demanded revolutionary change of the entire society and inner revolution in the individual personality in accordance with the authentic early Christian faith.

  12. Hydroxyl radical formation by dithranol.

    Science.gov (United States)

    Müller, K; Kappus, H

    1988-11-15

    Ethene formation from 2-keto-thiomethyl-butyric acid (KMBA) was used to measure hydroxyl radical generation from the antipsoriatic drug dithranol in phosphate buffer pH 7.8. Because the singlet oxygen (1O2) sensitizer, rose bengale, showed enlarged production of ethene when irradiated in the presence of KMBA, experiments were performed in the dark in order to avoid 1O2 production by dithranol. KMBA was converted to ethene by dithranol under aerobic conditions, whereas ethene formation was negligible in the absence of oxygen. Addition of catalytic amounts of FeCl3 resulted in increased ethene formation, indicating the catalysis of a superoxide-driven Fenton-reaction. O2- - and .OH-scavengers such as rutin, catechin, dimethyl sulfoxide, mannitol, ethanol, sodium salicylate and propyl gallate as well as catalase and superoxide dismutase inhibited ethene formation.

  13. 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.

  14. 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.

  15. 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).

  16. 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.

  17. 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...

  18. 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.

  19. 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.

  20. 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

  1. Radical Behaviorism and Buddhism: Complementarities and Conflicts

    Science.gov (United States)

    Diller, James W.; Lattal, Kennon A.

    2008-01-01

    Comparisons have been made between Buddhism and the philosophy of science in general, but there have been only a few attempts to draw comparisons directly with the philosophy of radical behaviorism. The present review therefore considers heretofore unconsidered points of comparison between Buddhism and radical behaviorism in terms of their…

  2. Free Radical Mechanisms in Autoxidation Processes.

    Science.gov (United States)

    Simic, Michael G.

    1981-01-01

    Discusses the use of steady-state radiation chemistry and pulse radiolysis for the generation of initial free radicals and formation of peroxy radicals in the autoxidation process. Provides information regarding the autoxidation process. Defines autoxidation reactions and antioxidant action. (CS)

  3. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    B. Mourrain; J.B. Lasserre; M. Laurent (Monique); P. Rostalski; P. Trebuchet (Philippe)

    2013-01-01

    htmlabstractIn this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and

  4. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    B. Mourrain; J.B. Lasserre; M. Laurent (Monique); P. Rostalski; P. Trebuchet (Philippe)

    2011-01-01

    htmlabstractIn this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and

  5. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    Lasserre, J.B.; Laurent, M.; Mourrain, B.; Rostalski, P.; Trébuchet, P.

    2013-01-01

    In this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming its complex (resp. real) variety is finite. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and semi-definite

  6. Free radical scavenging activity of Lafoensia pacari.

    Science.gov (United States)

    Solon, S; Lopes, L; Teixeira de Sousa, P; Schmeda-Hirschmann, G

    2000-09-01

    The methanolic extract of the stem bark of Lafoensia pacari (Lythraceae) showed free radical scavenging activity in the diphenyl picryl hydrazyl radical (DPPH) decoloration assay and inhibited the enzyme xanthine oxidase 'in vitro'. Bioassay-guided isolation led to ellagic acid (EA) as the main active compound of Brazilian and Paraguayan collections of the plant.

  7. An Appreciation of Free Radical Chemistry

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 9. An Appreciation of Free Radical Chemistry - 6. Experiments Involving Free Radicals. G Nagendrappa. Classroom Volume 10 Issue 9 September 2005 pp 79-84 ...

  8. EPR spin trapping of protein radicals

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan; Hawkins, Clare Louise

    2004-01-01

    Electron paramagnetic resonance (EPR) spin trapping was originally developed to aid the detection of low-molecular-mass radicals formed in chemical systems. It has subsequently found widespread use in biology and medicine for the direct detection of radical species formed during oxidative stress ...

  9. Resonance raman studies of phenylcyclopropane radical cations

    NARCIS (Netherlands)

    Godbout, J.T.; Zuilhof, H.; Heim, G.; Gould, I.R.; Goodman, J.L.; Dinnocenzo, J.P.; Myers Kelley, A.

    2000-01-01

    Resonance Raman spectra of the radical cations of phenylcyclopropane and trans-1-phenyl-2-methylcyclopropane are reported. A near-UV pump pulse excites a photosensitizer which oxidizes the species of interest, and a visible probe pulse delayed by 35 ns obtains the spectrum of the radical ion. The

  10. Allylthioketone Mediated Free Radical Polymerization of Methacrylates

    Directory of Open Access Journals (Sweden)

    Feng Zhong

    2017-11-01

    Full Text Available By combination of high trapping free radical efficiency of the thioketone and resonance of the allylic radical, a new type of mediating agent, 1,3,3-triphenylprop-2-ene-1-thione (TPPT has been successfully synthesized, and then is used to study controlled free radical polymerization of methacrylates. Very stable TPPT radicals at the end of poly(methyl methacrylate (PMMA are detected in the polymerization of MMA using TPPT and AIBN as the control agent and initiator. The MALDI-TOF MS spectra are used to identify terminal groups of the resultant poly(glycidyl methacrylate (PGMA, and major component of the obtained polymer has the structure, (CH32(CNC-PGMA-C7H9O3. Chain extension reaction tests ascertain formation of the dead polymers during the polymer storage and purification process of the polymers. Owing to very slow fragmentation reaction of the TPPT-terminated polymethacrylate radical and addition reaction of this radical with a primary radical, the growing chain radicals are difficult to be regenerated, leading to an unobvious change of the molecular weight with monomer conversion. The molecular weights of polymers can be controlled by the ratios of monomer/initiator and TPPT/initiator. However, the first order kinetics of the polymerization and the polymers with narrow polydispersity are obtained, and these phenomena are discussed. This study provides useful information on how to design a better controlling agent.

  11. Ideals Adrift: An Educational Approach to Radicalization

    Science.gov (United States)

    van San, Marion; Sieckelinck, Stijn; de Winter, Micha

    2013-01-01

    These days, the radicalization of young people is above all viewed as a security risk. Almost all research into this phenomenon has been carried out from a legal, criminological or socio-psychological perspective with a focus on detecting and containing the risks posed by radicalization. In the light of the political developments since September…

  12. Free radicals in biology. Volume II

    International Nuclear Information System (INIS)

    Pryor, W.A.

    1976-01-01

    This volume continues the treatment of topics in free radical biology and free radical pathology from Volume I. In the first chapter, pyridinyl radicals, radicals which are models for those derived from NAD, are discussed. Pyridinyl radicals can be synthesized and isolated and directly studied in a number of chemical systems. The next chapter treats the role of glutathione in the cell. It is becoming even more apparent that this vital thiol controls a large number of important cellular functions. The GSH/GSSG balance has recently been implicated as a control for cellular development; this balance also may be important in relaying the effects of oxidants from one site to another in the body. The next chapter outlines the reactions of singlet oxygen; some of these involve free radicals and some do not. This reactive intermediate appears to be important both in photochemical smog and in cellular chemistry where singlet oxygen is produced by nonphotochemical processes. The production of free radicals from dry tissues, a controversial area with conflicting claims is reviewed. The next chapter outlines the current status of the studies of photochemical smog. The next two chapters treat specific reactive materials which are present in smog. The first discusses the chemistry of nitrogen oxides and ozone. The second chapter treats the chemistry of the peroxyacyl nitrites. These compounds, although present in only small concentration, are among the most toxic components of smog. The last two chapters treat radiation damage to proteins and radiation protection and radical reactions produced by radiation in nucleic acids

  13. Victimology: A Consideration of the Radical Critique.

    Science.gov (United States)

    Friedrichs, David O.

    1983-01-01

    Discusses the emergence of a new radical model in criminology and a new subdisciplinary area of concern, victimology, with roots in Marx and Engels' original formulations. Argues that the radical understanding of victimization provides an important corrective to mainstream approaches and broadens the focus of the concept of victimization. (JAC)

  14. Electronic structure and properties of hydroxyalkyl radicals

    International Nuclear Information System (INIS)

    Kosobutskij, V.S.; Majboroda, V.D.; Petryaev, E.P.

    1989-01-01

    Quantum-chemical calculation using the MNDo method of hydroxymethyl and hydroxyethyl radicals and corresponding anion-radicals is made. Electron structure of radical particles differs considerably from the structure of initial alcohols. From the viewpoint of perturbation theory of molecular orbitals it is shown that noncoupled electron in hydroxyalkyl radicals and radical-anions occupies the loosening orbital. For this reason the above-mentioned particles easily enter the reactions of electron transfer on the acceptor and are not active in reactions of break-off and addition via binary bond. Theoretical concepts are confirmed by experimental data, obtained when studying gamma-radiolysis of methanol solution in water and in 5M NaOH aqueous solution (dose rate is 0.478 Gy/s, dose range is 0.796-4.293 kGy)

  15. In vitro study of cytotoxicity by U.V. radiation and differential sensitivity in combination with alkylating agents on established cell systems

    International Nuclear Information System (INIS)

    Ramudu, K.

    1991-01-01

    The effect of U.V. radiation or alkylating agents, such as actinomycin-D, cycloheximide and mitomycin-C (MMC), was studied on CHO, BHK and HeLa cells. U.V. radiation caused DNA ssb and dsb and were prevented by cycloheximide and actinomycin-D. MMC is known to be cytotoxic in CHO/BHK cells by forming free radical generation. MMC in combination with U.V. radiation enhanced DNA ssb ampersand dsb in these cell types. However, HeLa cells were insensitive to U.V. radiation. This insensitivity to U.V. radiation could be ascribed to the presence of glutathione transferase which is absent in CHO/BHK cell line

  16. 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

  17. Hydroxyl-radical-induced oxidation of cyclic dipeptides: Reactions of free peptide radicals and their peroxyl radicals

    International Nuclear Information System (INIS)

    Mieden, O.J.

    1989-01-01

    In the course of this study investigations were carried out into the reactions of hydroxyl radicals and hydrogen atoms with cyclic dipeptides as well as the subsequent reactions of peptide radicals and their peroxyl radicals in aqueous solution. The radiolysis products formed in the absence and presence of oxygen or transient metal complexes were characterized and determined on a quantitative basis. The linking of information from product analyses to the kinetic data for transient species obtained by time-resolving UV/VIS and conductivity measurements (pulse radiolysis) as well as computer-assisted simulations of individual events during the reaction permitted an evaluation of the mechanisms underlying the various processes and an identification of interim products with short life-times, which did or did not belong to the group of radicals. Through the characterization of key reactions of radicals and peroxyl radicals of this substance class a major advance has been made towards a better understanding of the role of radicals in the peptide compound and the mechanisms involved in indirect radiation effects on long-chain peptides and proteins. (orig.) [de

  18. 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...

  19. 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...

  20. Non-enzymatic modifications in metallothioneins connected to lipid membrane damages: structural and biomimetic studies under reductive radical stress.

    Science.gov (United States)

    Torreggiani, Armida; Chatgilialoglu, Chryssostomos; Ferreri, Carla; Melchiorre, Michele; Atrian, Silvia; Capdevila, Merce'

    2013-10-30

    . The chemical mechanism involving sulfur-containing moieties under reductive conditions discloses new scenarios that bring to the loss of sulfur-centered radicals by desulfurization reactions that change the natural sequences of MTs. Ala is a genetically coded amino acid, therefore the mutation of Cys to Ala occurring to a sequence by the radical process so far discussed, corresponds to a post-translational modification. Research on such mutation connected also to a free radical stress will be important to contribute for a complete picture of the degeneration associated to diseases and aging. Analogously, the Met to Aba mutation occurring after reductive stress transforms a natural amino acid into a natural, non-genetically-coded congener. Aba corresponds to a homologation of the alkyl chains normally present in genetically codified amino acids, such as methyl (in Ala) and isopropyl (in Leu), with an ethyl unit. Based on alkyl substitution, this modification can therefore be studied in order to understand its general consequences on the structure-activity relationships in proteins and, in particular, on molecular interactions. This article is part of a Special issue entitled: Posttranslational Protein modifications in biology and Medicine. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Part I. An investigation into the mechanism of the samarium (II)-promoted Barbier reaction: Sequential radical cyclization/organometallic addition. Part II. Conjugate addition reactions of organosamarium reagents by in situ transmetalation to cuprates. Part III. Approximate absolute rate constants for the reaction of tributyltin radicals with aryl and vinyl halides. Part IV. An investigation into the synthetic utility of tri-n-butylgermanium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Totleben, M.J.

    1992-01-01

    An investigation of the mechanism of the samarium diiodide mediated Barbier reaction was conducted. Through a series of alkyl halide-carbonyl coupling and deuterium labelling experiments, evidence supportive of an organometallic addition mechanism was collected. Further probing led to an expansion of the utility of SmI[sub 2] in synthesis. The author has shown that radical cyclization of aryl and alkyl radicals to olefins, followed by reduction to primary and secondary organosamarium species is feasible. Organosamarium (III) reagents, produced by the reduction of alkyl and select aryl halides with 2 equiv of SmI[sub 2] in THF/HMPA, were treated with copper (I) salts and complexes to effect in situ transmetalation to cuprates. This allowed the 1,4-addition to [alpha],[beta]-unsaturated ketones. This new methodology allows for the sequential formation of carbon-carbon bonds through a combination of free radical and cuprate chemistry. Absolute rate constants for the abstraction of bromine atoms (k[sub Br]) by tri-n-butyltin radicals from a series of vinyl and aryl bromides have been determined. Atom abstraction was modestly enhanced by proximity of the halogen to a substituent in the following order: para < meta < ortho. Tri-n-butyl germanium hydride is known to be a poorer hydrogen atom donor than its tin analog. This feature makes it attractive for use in slow radical cyclizations where tin hydride would provide mainly for reduction. A brief study was executed to improve on the utility of the reagent as current conditions do not yield desired products in high amounts. Initial investigations examined the effect of initiator on reduction by germanium hydride, and subsequent experiments probed solvent effects. t-Butyl alcohol was determined to be superior to benzene or acetonitrile, giving consistently higher yields of reduction products.

  14. Fluoropolymer materials and architectures prepared by controlled radical polymerizations

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie; Jankova Atanasova, Katja; Hvilsted, Søren

    2007-01-01

    This review initially summarizes the mechanisms, merits and limitations of the three controlled radical polymerizations: nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP) or metal catalyzed living radical polymerization, and reversible addition–fragmentation chain...

  15. 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.

  16. Involvement of free radicals in breast cancer.

    Science.gov (United States)

    Ríos-Arrabal, Sandra; Artacho-Cordón, Francisco; León, Josefa; Román-Marinetto, Elisa; Del Mar Salinas-Asensio, María; Calvente, Irene; Núñez, Maria Isabel

    2013-08-27

    Researchers have recently shown an increased interest in free radicals and their role in the tumor microenvironment. Free radicals are molecules with high instability and reactivity due to the presence of an odd number of electrons in the outermost orbit of their atoms. Free radicals include reactive oxygen and nitrogen species, which are key players in the initiation and progression of tumor cells and enhance their metastatic potential. In fact, they are now considered a hallmark of cancer. However, both reactive species may contribute to improve the outcomes of radiotherapy in cancer patients. Besides, high levels of reactive oxygen species may be indicators of genotoxic damage in non-irradiated normal tissues. The purpose of this article is to review recent research on free radicals and carcinogenesis in order to understand the pathways that contribute to tumor malignancy. This review outlines the involvement of free radicals in relevant cellular events, including their effects on genetic instability through (growth factors and tumor suppressor genes, their enhancement of mitogenic signals, and their participation in cell remodeling, proliferation, senescence, apoptosis, and autophagy processes; the possible relationship between free radicals and inflammation is also explored. This knowledge is crucial for evaluating the relevance of free radicals as therapeutic targets in cancer.

  17. 'Living'-chain radical polymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Korolev, Gennadii V; Marchenko, A P [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2000-05-31

    The review is devoted to various types of compounds used as agents for 'living' radical polymerisation, such as alkoxyamines formed upon addition of the chain carrier radicals, R{sup .}, to stable nitroxyl radicals, as well as products of the addition of the radicals to transition metal complexes with different ligands, etc. In all cases, the mechanism of the action of these agents consists in their reversible dissociation ArightleftarrowsR{sup .} + X{sup .}, where X{sup .} is a stable free radical or a metal-containing complex which can accept radicals R{sup .} (R{sup .} + X{sup .}{yields}A) and thus compete with the quadratic chain termination. Particular attention is paid to the studies which allowed a quantitative formulation of the mechanism of 'living' radical polymerisation in the form of a mathematical model suitable for predicting both the parameters of the polymerisation and the properties of the resulting polymer (molecular mass and polydispersity). The bibliography includes 359 references.

  18. 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

  19. Comparison of Antioxidant Evaluation Assays for Investigating Antioxidative Activity of Gallic Acid and Its Alkyl Esters in Different Food Matrices.

    Science.gov (United States)

    Phonsatta, Natthaporn; Deetae, Pawinee; Luangpituksa, Pairoj; Grajeda-Iglesias, Claudia; Figueroa-Espinoza, Maria Cruz; Le Comte, Jérôme; Villeneuve, Pierre; Decker, Eric A; Visessanguan, Wonnop; Panya, Atikorn

    2017-08-30

    The addition of antioxidants is one of the strategies to inhibit lipid oxidation, a major cause of lipid deterioration in foods leading to rancidity development and nutritional losses. However, several studies have been reported that conventional antioxidant assays, e.g., TPC, ABTS, FRAP, and ORAC could not predict antioxidant performance in several foods. This study aimed to investigate the performance of two recently developed assays, e.g., the conjugated autoxidizable triene (CAT) and the apolar radical-initiated conjugated autoxidizable triene (ApoCAT) assays to predict the antioxidant effectiveness of gallic acid and its esters in selected food models in comparison with the conventional antioxidant assays. The results indicated that the polarities of the antioxidants have a strong impact on antioxidant activities. In addition, different oxidant locations demonstrated by the CAT and ApoCAT assays influenced the overall antioxidant performances of the antioxidants with different polarities. To validate the predictability of the assays, the antioxidative performance of gallic acid and its alkyl esters was investigated in oil-in-water (O/W) emulsions, bulk soybean oils, and roasted peanuts as the lipid food models. The results showed that only the ApoCAT assay could be able to predict the antioxidative performances in O/W emulsions regardless of the antioxidant polarities. This study demonstrated that the relevance of antioxidant assays to food models was strongly dependent on physical similarities between the tested assays and the food structure matrices.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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...

  6. 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

  7. 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....

  8. 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.

  9. 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.

  10. Editorial: From Radicalism to Minority Issues

    Directory of Open Access Journals (Sweden)

    Editor Al-Jami'ah Journal of Islamic Studies

    2014-06-01

    Full Text Available This edition presents contemporary themes around Islam and Muslims in Indonesia from the issues of radicalism, online media, a Dutch scholar during colonial era, women’s resistance to shariatization, local practice of Islamic sufism, minority group, to broader theme of the relation of religion and science. To begin with, James Adam Fenton sheds light on the way in which Indonesian society has responded to radical ideology. He argues that dialogue in open society with democratic spirit helps the society to disengage from radicalism.

  11. User involvement competence for radical innovation

    DEFF Research Database (Denmark)

    Lettl, Christopher

    2007-01-01

    -assisted navigation systems. The case study analysis reveals that firms who closely interact with specific users benefit significantly for their radical innovation work. These users have a high motivation toward new solutions, are open to new technologies, possess diverse competencies, and are embedded into a very......One important market related capability for firms which seek to develop radical innovations is the competence to involve the 'right' users at the 'right' time in the 'right' form. While former studies have identified a rather passive role of users in the radical innovation process, this paper...

  12. Competition of charge- versus radical-directed fragmentation of gas-phase protonated cysteine sulfinyl radicals.

    Science.gov (United States)

    Love, Chasity B; Tan, Lei; Francisco, Joseph S; Xia, Yu

    2013-04-24

    The fragmentation behavior of various cysteine sulfinyl ions (intact, N-acetylated, and O-methylated), new members of the gas-phase amino acid radical ion family, was investigated by low-energy collision-induced dissociation (CID). The dominant fragmentation channel for the protonated cysteine sulfinyl radicals ((SO•)Cys) was the radical-directed Cα-Cβ homolytic cleavage, resulting in the formation of glycyl radical ions and loss of CH2SO. This channel, however, was not observed for protonated N-acetylated cysteine sulfinyl radicals (Ac-(SO•)Cys); instead, charge-directed H2O loss followed immediately by SH loss prevailed. Counterintuitively, the H2O loss did not derive from the carboxyl group but involved the sulfinyl oxygen, a proton, and a Cβ hydrogen atom. Theoretical calculations suggested that N-acetylation significantly increases the barrier (~14 kcal mol(-1)) for the radical-directed fragmentation channel because of its reduced capability to stabilize the thus-formed glycyl radical ions via the captodative effect. N-Acetylation also assists in moving the proton to the sulfinyl site, which reduces the barrier for H2O loss. Our studies demonstrate that for cysteine sulfinyl radical ions, the stability of the product ions (glycyl radical ions) and the location of the charge (proton) can significantly modulate the competition between radical- and charge-directed fragmentation.

  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. In Vitro Antimicrobial Bioassays, DPPH Radical Scavenging Activity, and FTIR Spectroscopy Analysis of Heliotropium bacciferum

    Directory of Open Access Journals (Sweden)

    Sohail Ahmad

    2016-01-01

    Full Text Available The present study deals with the antimicrobial, antioxidant, and functional group analysis of Heliotropium bacciferum extracts. Disc diffusion susceptibility method was followed for antimicrobial assessment. Noteworthy antimicrobial activities were recorded by various plant extracts against antibiotic resistant microorganisms. Plant flower extracts antioxidant activity was investigated against 2, 2-diphenyl-1-picryl hydrazyl radical by ultraviolet spectrophotometer (517 nm. Plant extracts displayed noteworthy radical scavenging activities at all concentrations (25–225 μg/mL. Notable activities were recorded by crude, chloroform and ethyl acetate extracts up to 88.27% at 225 μg/mL concentration. Compounds functional groups were examined by Fourier transform infrared spectroscopic studies. Alkanes, alkenes, alkyl halides, amines, carboxylic acids, amides, esters, alcohols, phenols, nitrocompounds, and aromatic compounds were identified by FTIR analysis. Thin layer chromatography bioautography was carried out for all plant extracts. Different bands were separated by various solvent systems. The results of the current study justify the use of Heliotropium bacciferum in traditional remedial herbal medicines.

  16. In Vitro Antimicrobial Bioassays, DPPH Radical Scavenging Activity, and FTIR Spectroscopy Analysis of Heliotropium bacciferum.

    Science.gov (United States)

    Ahmad, Sohail; AbdEl-Salam, Naser M; Ullah, Riaz

    2016-01-01

    The present study deals with the antimicrobial, antioxidant, and functional group analysis of Heliotropium bacciferum extracts. Disc diffusion susceptibility method was followed for antimicrobial assessment. Noteworthy antimicrobial activities were recorded by various plant extracts against antibiotic resistant microorganisms. Plant flower extracts antioxidant activity was investigated against 2, 2-diphenyl-1-picryl hydrazyl radical by ultraviolet spectrophotometer (517 nm). Plant extracts displayed noteworthy radical scavenging activities at all concentrations (25-225 μg/mL). Notable activities were recorded by crude, chloroform and ethyl acetate extracts up to 88.27% at 225 μg/mL concentration. Compounds functional groups were examined by Fourier transform infrared spectroscopic studies. Alkanes, alkenes, alkyl halides, amines, carboxylic acids, amides, esters, alcohols, phenols, nitrocompounds, and aromatic compounds were identified by FTIR analysis. Thin layer chromatography bioautography was carried out for all plant extracts. Different bands were separated by various solvent systems. The results of the current study justify the use of Heliotropium bacciferum in traditional remedial herbal medicines.

  17. Radical Pancreaticoduodenectomy for Benign Disease

    Directory of Open Access Journals (Sweden)

    D. O. Kavanagh

    2008-01-01

    Full Text Available Whipple's procedure is the treatment of choice for pancreatic and periampullary malignancies. Preoperative histological confirmation of malignancy is frequently unavailable and some patients will subsequently be found to have benign disease. Here, we review our experience with Whipple's procedure for patients ultimately proven to have benign disease. The medical records of all patients who underwent Whipple's procedure during a 15-year period (1987–2002 were reviewed; 112 patients underwent the procedure for suspected malignancy. In eight cases, the final histology was benign (7.1%. One additional patient was known to have benign disease at resection. The mean age was 50 years (range: 30–75. The major presenting features included jaundice (five, pain (two, gastric outlet obstruction (one, and recurrent gastrointestinal haemorrhage (one. Investigations included ultrasound (eight, computerised tomography (eight, endoscopic retrograde cholangiopancreatography (seven; of these, four patients had a stent inserted and three patients had sampling for cytology, and endoscopic ultrasound (two. The pathological diagnosis included benign biliary stricture (two, chronic pancreatitis (two, choledochal cyst (one, inflammatory pseudotumour (one, cystic duodenal wall dysplasia (one, duodenal angiodysplasia (one, and granular cell neoplasm (one. There was no operative mortality. Morbidity included intra-abdominal collection (one, anastomotic leak (one, liver abscess (one, and myocardial infarction (one. All patients remain alive and well at mean follow-up of 41 months. Despite recent advances in diagnostic imaging, 8% of the patients undergoing Whipple'’s procedure had benign disease. A range of unusual pathological entities can mimic malignancy. Accurate preoperative histological diagnosis may have allowed a less radical operation to be performed. Endoscopic ultrasound–guided fine needle aspirate (EUS-FNA may reduce the need for Whipple's operation in

  18. Radical pancreaticoduodenectomy for benign disease.

    LENUS (Irish Health Repository)

    Kavanagh, D O

    2008-01-01

    Whipple\\'s procedure is the treatment of choice for pancreatic and periampullary malignancies. Preoperative histological confirmation of malignancy is frequently unavailable and some patients will subsequently be found to have benign disease. Here, we review our experience with Whipple\\'s procedure for patients ultimately proven to have benign disease. The medical records of all patients who underwent Whipple\\'s procedure during a 15-year period (1987-2002) were reviewed; 112 patients underwent the procedure for suspected malignancy. In eight cases, the final histology was benign (7.1%). One additional patient was known to have benign disease at resection. The mean age was 50 years (range: 30-75). The major presenting features included jaundice (five), pain (two), gastric outlet obstruction (one), and recurrent gastrointestinal haemorrhage (one). Investigations included ultrasound (eight), computerised tomography (eight), endoscopic retrograde cholangiopancreatography (seven; of these, four patients had a stent inserted and three patients had sampling for cytology), and endoscopic ultrasound (two). The pathological diagnosis included benign biliary stricture (two), chronic pancreatitis (two), choledochal cyst (one), inflammatory pseudotumour (one), cystic duodenal wall dysplasia (one), duodenal angiodysplasia (one), and granular cell neoplasm (one). There was no operative mortality. Morbidity included intra-abdominal collection (one), anastomotic leak (one), liver abscess (one), and myocardial infarction (one). All patients remain alive and well at mean follow-up of 41 months. Despite recent advances in diagnostic imaging, 8% of the patients undergoing Whipple\\'s procedure had benign disease. A range of unusual pathological entities can mimic malignancy. Accurate preoperative histological diagnosis may have allowed a less radical operation to be performed. Endoscopic ultrasound-guided fine needle aspirate (EUS-FNA) may reduce the need for Whipple\\'s operation

  19. Day case laparoscopic radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Hamid Abboudi

    2017-10-01

    Full Text Available Background: To evaluate the feasibility of performing laparoscopic radical prostatectomy (LRP as a day case procedure while maintaining patient satisfaction and safety. Herein we report our experience, selection criteria, and discharge criteria for day case LRP. Methods: We performed a prospective study with 32 patients undergoing extraperitoneal LRP. These patients were counselled before the procedure that they would go home the same evening of the procedure. Pain scores and quality of life data were recorded day 1 postoperatively via a telephone consultation. The patients underwent routine blood tests on day 2 and an outpatient review on day 7 and regularly thereafter via an assigned key worker. Socio-demographic data, comorbidities, and outcomes were collected for analysis. Results: All patients were successfully discharged the same day of surgery. Mean patient age was 62 years with a mean body mass index of 25. Mean operative time was 147 minutes, and estimated blood loss was 101 ml. Three patients were treated for post operative urinary tract infections; two patients developed infected lymphoceles which required percutaneous drainage and one patient required re-catheterisation due to a burst catheter balloon. Of these six complications four patients required re-admission. Post-operative pain, nausea and vomiting were low whilst patient satisfaction scores were unanimously high in all patients surveyed. Conclusions: The early experience with extraperitoneal LRP as a same day surgery is promising although patients who are at high risk of lymphocele should be excluded. Preoperative patient counselling and selection is paramount. Patient satisfaction is not adversely affected by the shortened stay. Surgeon experience, a well-motivated patient, meticulous attention to detail through an integrated pathway, a multidisciplinary team and adequate postoperative assessment are essential.

  20. An in situ radiolysis EPR study of spin trapping by 2-methyl-2-nitrosopropane: steric and electronic effects influencing the trapping of hydroxyalkyl radicals derived from pentanols and substituted pentanols

    International Nuclear Information System (INIS)

    Madden, K.P.; Taniguchi, Hitoshi

    1993-01-01

    The spin adducts formed by reaction of bulky hydroxyalkyl radicals with the nitroso spin trap 2-methyl-2-nitrosopropane (MNP) were studied using in-situ radiolysis EPR. Parent hydroxyalkyl radicals were produced in aqueous solution either by hydroxyl-radical reaction with unsubstituted and methyl-substituted alcohols (propanols, pentanols and cyclohexanols) or by reaction of the corresponding ketone with the hydrated electron. All but the bulkiest radicals reacted with MNP by addition at the nitroso nitrogen site to form the MNP-C(OH)RR' spin adduct. Steric interactions strongly modulated the yields of the spin adducts produced. Strongly reducing hydroxyalkyl radicals also reacted with MNP to produce the MNP-H adduct by direct reduction of MNP. Steric hindrance between the parent radical and MNP was sufficient in the most extreme case to shut off MNP-R production with concomitant production of MNP-H. Spin-adduct persistence was measured for the MNP-hydroxyalkyl and MNP-alkyl spin adducts. Hydroxyalkyl spin adduct lifetimes varied from seconds (MNP-1 -hydroxy-1-methylbutyl) to one year (MNP-1-hydroxycyclohexyl), correlating with the level of aminoxyl function shielding afforded by its substituent groups. MNP spin adducts formed from other non-hydroxyalkyl alcohol radicals had short lifetimes of less than 18 hours. (Author)

  1. Psychopathology according to behaviorism: a radical restatement.

    Science.gov (United States)

    Pérez-Alvarez, Marino

    2004-11-01

    This article is a radical restatement of the predominant psychopathology, which is characterized by nosological systems and by its approach towards a neurobiological conception of the so-called mental disorders. The "radical" sense of this restatement is that of radical behaviorism itself. As readers will recall, "radical" applied to behaviorism means total (not ignoring anything that interests psychology), pragmatic (referring to the practical sense of knowledge), and it also derives from the Latin word for "root" (and thus implies change beginning at a system's roots or getting to the root of things, in this case, of psychological disorders). Based on this, I introduce the Aristotelian distinction of material and form, which, besides being behaviorist avant la lettre, is used here as a critical instrument to unmask the hoax of psychopathology as it is presented. The implications of this restatement are discussed, some of them already prepared for clinical practice.

  2. Interactions between simple radicals and water

    International Nuclear Information System (INIS)

    Crespo-Otero, Rachel; Sanchez-Garcia, Elsa; Suardiaz, Reynier; Montero, Luis A.; Sander, Wolfram

    2008-01-01

    The interactions of the simple radicals CH 3 , NH 2 , OH, and F with water have been studied by DFT (UB3LYP/6-311++G(2d,2p)) and ab initio (RHF-UCCSD(T)/6-311++G(2d,2p)) methods. In this order the number of lone pairs (from zero to three), the electronegativity, and the strength of the X-H bonds increase (X = C, N, and O). The various minima of the radical-water complexes were located using the multiple minima hypersurface (MMH) approach which had previously been proven to be useful for closed-shell molecules. The role of the unpaired electron in hydrogen bonding was investigated using the natural bond orbital (NBO) analysis. A considerable contribution of the unpaired electron to the complex stabilization was only found for the methyl radical and the fluorine atom, whereas in the aminyl and the hydroxyl radical the role of the unpaired electron is negligible

  3. Photodynamically generated bovine serum albumin radicals

    DEFF Research Database (Denmark)

    Silvester, J A; Timmins, G S; Davies, Michael Jonathan

    1998-01-01

    Porphyrin-sensitized photoxidation of bovine serum albumin (BSA) results in oxidation of the protein at (at least) two different, specific sites: the Cys-34 residue giving rise to a thiyl radical (RS.); and one or both of the tryptophan residues (Trp-134 and Trp-214) resulting in the formation...... of tertiary carbon-centred radicals and disruption of the tryptophan ring system. In the case of porphyrins such as hematoporphyrin, which bind at specific sites on BSA, these species appear to arise via long-range transfer of damage within the protein structure, as the binding site is some distance from...... the ultimate site of radical formation. This transfer of damage is shown to depend on a number of factors including the conformation of the protein, the presence of blocking groups and pH. Alteration of the protein conformation results in radical formation at additional (or alternative) sites, as does blocking...

  4. Radicalization and the Use of Social Media

    Directory of Open Access Journals (Sweden)

    Robin Thompson

    2011-01-01

    Full Text Available The use of social media tools by individuals and organizations to radicalize individuals for political and social change has become increasingly popular as the Internet penetrates more of the world and mobile computing devices are more accessible. To establish a construct for radicalization,the power and reach of social media will be described so there is common understanding of what social media is and how it is utilized by various individuals and groups. The second section will answer the question of why social media applications are the perfect platform for the radical voice. Finally, the use of social media and its influence in radicalizing populations in Northern Africa and the Middle East during 2011 will be analyzed and recommendations proposed.

  5. Radical Sustainable Innovation of office buildings

    DEFF Research Database (Denmark)

    Koch, Christian; Berker, Thomas; Koch-Ørvad, Nina

    2017-01-01

    by high degrees of newness in the entire life cycle. RSI should offer significant enhancements of known benefits, entirely new benefits, or substantial cost reductions, leading to the transformation of existing markets, the creation of sustainable growth, and global sustainability. Thus, if buildings were......The recent development of technologies, processes and methods of sustainable building has enabled an unprecedented quantum leap in the available solutions. These possibilities could be interpreted as radical, yet they appear at a time as results of a long emergent development. The aim of this paper...... is to critically scrutinize, theoretically and empirically, whether radical innovation is occurring in sustainable building and what the implication are. The theoretical framework is based on concepts of radical innovation, inventions and sustainability. Radical sustainable innovation (RSI) should be characterized...

  6. Prison Radicalization: The New Extremist Training Grounds?

    National Research Council Canada - National Science Library

    Coffin, Jr., McKinley D

    2007-01-01

    As a nation with the largest prison population in the world, the United States has all the ingredients for criminals, extremists, and religious radicals to collaborate in producing a new breed of homegrown terrorist...

  7. Sphingomyelinase inhibitory and free radical scavenging potential ...

    African Journals Online (AJOL)

    Sphingomyelinase inhibitory and free radical scavenging potential of selected Nigerian medicinal plant extracts. FM Awah, PN Uzoegwu, P Ifeonu, JO Oyugi, J Rutherford, X Yao, F Fehrmann, KR Fowke, MO Eze ...

  8. Free radical scavenging activity of papaya juice

    Energy Technology Data Exchange (ETDEWEB)

    Webman, E.J.; Mower, H.F.; Edlin, Gordon

    1989-03-01

    Papaya juice is an efficient scavenger of highly reactive hydroxyl radicals (OH radical) formed during /sup 60/Co irradiation of water. The OH anion radicals were detected by the electron spin resonance (ESR) technique of spin trapping using DMPO (5,5-dimethyl-1-pyrroline-N-oxide) or by a colorimetric assay in which salicylate is converted into polyhydroxybenzoic acids. Papaya juice is also able to quench the ESR signal of a stable free radical (TEMPOL) and the ESR signal of the DMPO-OH adduct. The active substance(s) in papaya juice are heat-stable, dialyzable, and soluble in water but not in lipid solvents. The active agents do not appear to be ascorbate, tocopherol, or carotenoids.

  9. ESR of radicals captured in coal

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Y.; Yamakawa, T.

    1986-01-01

    A study is reported of the interrelation between the state of movement exhibited by a spin probe radical added to Morwell, Wandoan and Liddell coals, and 1) the pore structure of the coals, 2) the configuration of their functional groups. The radicals used as the spin probe was 2,2,6,6-tetramethyl-4-piperidinol-1-oxyl (TEMPOL). In the case of Wandoan coal, the probe radical entered the pores, with the result that the degree of freedom of its rotational movement remained restricted up to high temperatures. With Liddell coal, the shift to free rotation took place over a broader range of temperatures. This was due to the distribution of active sites where interaction with the introduced radical molecules was possible. 14 references, 6 figures, 3 tables.

  10. Proton hyperfine tensors in nitroxide radicals

    Energy Technology Data Exchange (ETDEWEB)

    Brustolon, M.; Maniero, A.L.; Segre, U. (Universita di Padova (Italy)); Ottaviani, M.F. (Universita di Firenze (Italy)); Romanelli, M. (Universita della Basilicata (Italy))

    1990-08-23

    The proton hyperfine tensors of five nitroxide radicals have been obtained by ENDOR spectroscopy in frozen solution. The spectra are interpreted by computing the dipolar hyperfine interaction and simulating the spectra. EPR spectra in solution of the same radicals have been simulated by taking into account the effects of the proton hyperfine tensors. We have been able to reproduce accurately the line broadening effects of the proton hyperfine structures inside each nitrogen hyperfine component and we have determined the correlation times for the rotational motion. In the case of the radical Tempol, our analysis allows discrimination between the effects due to the protons of the axial and equatorial methyl groups. On the basis of experimental evidence we can attribute the larger isotropic hyperfine coupling constant to the axial methyl protons. The possible use of the present results for interpreting the spectra of other nitroxide radicals is discussed.

  11. Neo-liberal Governing of 'Radicals'

    DEFF Research Database (Denmark)

    Lindekilde, Lasse

    2012-01-01

    The Danish government’s counter-radicalization Action Plan of 2009 had intended and unintended effects. Primarily targeting Danish Muslims, it employs neoliberal governmentality approaches of governance through individual support and response, information and knowledge, empowerment, surveillance...

  12. Fast beam studies of free radical photodissociation

    Energy Technology Data Exchange (ETDEWEB)

    Neumark, D.M. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    The authors have developed a novel technique for studying the photodissociation spectroscopy and dynamics of free radicals. In these experiments, radicals are generated by laser photodetachment of a fast (6-8 keV) mass-selected negative ion beam. The resulting radicals are photodissociated with a second laser, and the photofragments are collected and detected with high efficiency using a microchannel plate detector. The overall process is: ABC{sup -} {yields} ABC + e{sup -} {yields} A + BC, AB + C. Two types of fragment detection schemes are used. To map out the photodissociation cross-section of the radical, the photodissociation laser is scanned and the total photofragment yield is measured as a function of wavelength. In other experiments, the photodissociation frequency is fixed and the photofragment masses, kinetic energy release, and scattering angle is determined for each photodissociation event.

  13. The formation of [M-H]+ ions in N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione derivatives during atmospheric pressure photoionization mass spectrometry

    KAUST Repository

    Sioud, Salim

    2014-10-09

    RESULTS [M-H]+ ions were observed under APPI conditions. The type of dopant and the length of the alkyl chain affected the formation of these ions. MS/MS fragmentation of [M-H]+ and [M + H]+ ions exhibited completely different patterns. Theoretical calculations revealed that the loss of hydrogen molecules from the [M + H]+ ions is the most favourable condition under which to form [M-H]+ ions.CONCLUSIONS [M-H]+ ions were detected in all the TPD derivatives studied here under the special experimental conditions during APPI, using a halogenated benzene dopant, and TPD containing substituted N-alkyl side chains with a minimum of four carbon atoms. Density functional theory calculations showed that for [M-H]+ ions to be formed under these conditions, the loss of hydrogen molecules from the [M + H]+ ions is proposed to be necessary.RATIONALE The formation of ions during atmospheric pressure photoionization (APPI) mass spectrometry in the positive mode usually provides radical cations and/or protonated species. Intriguingly, during the analysis of some N-alkyl-substituted thieno[3,4-c]pyrrole-4,6-dione (TPD) derivatives synthesized in our laboratory, unusual [M-H]+ ion peaks were observed. In this work we investigate the formation of [M-H]+ ions observed under APPI conditions.METHODS Multiple experimental parameters, including the type of ionization source, the composition of the solvent, the type of dopant, the infusion flow rate, and the length of the alkyl side chain were investigated to determine their effects on the formation of [M-H]+ ions. In addition, a comparison study of the gas-phase tandem mass spectrometric (MS/MS) fragmentation of [M + H]+ vs [M-H]+ ions and computational approaches were used.

  14. Analysis of radicals of irradiated garlic

    International Nuclear Information System (INIS)

    Kameya, Hiromi; Kaimori, Yoshihiko; Ukai, Mitsuko

    2010-01-01

    The detection method of gamma ray irradiated garlic using Electron Spin Resonance(ESR)spectroscopy was studied. The ESR spectrum was consisted of one singlet signal at g=2.00. This signal is due to an organic free radical. Upon irradiation, the intensity of the signal was increased. Also two signals due to cellulose radical were detected nearby the singlet. The intensity of the singlet signal was increased as depend on the increase of the irradiation dose level. (author)

  15. [Early complications following open radical prostatectomy

    DEFF Research Database (Denmark)

    Roder, M.A.; Gruschy, L.; Brasso, K.

    2009-01-01

    INTRODUCTION: Radical prostatectomy has been offered as curative treatment for localized prostate cancer at Rigshospitalet since August 1995. We here report on postoperative complications in 719 patients operated during the 12-year-period from August 1995 to August 2007 with special emphasis...... patients (1,1%). One patient died within 30 days after surgery. CONCLUSION: Our results demonstrate that radical prostatectomy can be performed with a minimal mortality and an acceptable morbidity Udgivelsesdato: 2009/4/27...

  16. 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...

  17. 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.

  18. 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

  19. 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)

  20. 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