Formation of biologically relevant carboxylic acids during the gamma irradiation of acetic acid

Science.gov (United States)

Negron-Mendoza, A.; Ponnamperuma, C.

1976-01-01

Irradiation of aqueous solutions of acetic acid with gamma rays produced several carboxylic acids in small yield. Their identification was based on the technique of gas chromatography combined with mass spectrometry. Some of these acids are Krebs Cycle intermediates. Their simultaneous formation in experiments simulating the primitive conditions on the earth suggests that metabolic pathways may have had their origin in prebiotic chemical processes.

Ion-exclusion chromatography with conductimetric detection of aliphatic carboxylic acids on a weakly acidic cation-exchange resin by elution with benzoic acid-beta-cyclodextrin.

Science.gov (United States)

Tanaka, Kazuhiko; Mori, Masanobu; Xu, Qun; Helaleh, Murad I H; Ikedo, Mikaru; Taoda, Hiroshi; Hu, Wenzhi; Hasebe, Kiyoshi; Fritz, James S; Haddad, Paul R

2003-05-16

In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression.

Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent.

Science.gov (United States)

Ohta, Kazutoku; Ohashi, Masayoshi; Jin, Ji-Ye; Takeuchi, Toyohide; Fujimoto, Chuzo; Choi, Seong-Ho; Ryoo, Jae-Jeong; Lee, Kwang-Pill

2003-05-16

The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent.

Adsorption Equilibrium Equation of Carboxylic Acids on Anion-Exchange Resins in Water.

Science.gov (United States)

Kanazawa, Nobuhiro; Urano, Kohei; Kokado, Naohiro; Urushigawa, Yoshikuni

2001-06-01

The adsorption of propionic acid and benzoic acid on anion-exchange resins was analyzed, and an adsorption equilibrium equation of carboxylic acids was proposed. The adsorption of carboxylic acids on the anion-exchange resins was considered to be the sum of the physical adsorption of the molecule and the ion-exchange adsorption of the ion, which were independent of each other. For the physical adsorption of carboxylic acids, it was conformed to the Freundlich equation. For the ion-exchange adsorption of carboxylate ions, the equilibrium equation corresponded well with the experimental results for wide ranges of concentration and pH. The equation contains a selectivity coefficient S(A)(Cl) for the chloride ion versus the carboxylate ion, which was considered essentially a constant. The influent of the bicarbonate ion from carbon dioxide in air could also be expressed by the additional equilibrium equation with the selectivity coefficient S(HCO(3))(Cl) for the chloride ion versus the bicarbonate ion. Consequently, an adsorption equilibrium equation can estimate the equilibrium adsorption amounts. Even the effect of a coexisting bicarbonate ion is inconsequential when the parameters of the Freundlich isotherm equation and the selectivity coefficients of the carboxylate ion and the bicarbonate ion in each resin are determined in advance. Copyright 2001 Academic Press.

Carboxylic acids in crystallization of macromolecules: learning from successful crystallization experiments.

Science.gov (United States)

Offermann, Lesa R; He, John Z; Mank, Nicholas J; Booth, William T; Chruszcz, Maksymilian

2014-03-01

The production of macromolecular crystals suitable for structural analysis is one of the most important and limiting steps in the structure determination process. Often, preliminary crystallization trials are performed using hundreds of empirically selected conditions. Carboxylic acids and/or their salts are one of the most popular components of these empirically derived crystallization conditions. Our findings indicate that almost 40 % of entries deposited to the Protein Data Bank (PDB) reporting crystallization conditions contain at least one carboxylic acid. In order to analyze the role of carboxylic acids in macromolecular crystallization, a large-scale analysis of the successful crystallization experiments reported to the PDB was performed. The PDB is currently the largest source of crystallization data, however it is not easily searchable. These complications are due to a combination of a free text format, which is used to capture information on the crystallization experiments, and the inconsistent naming of chemicals used in crystallization experiments. Despite these difficulties, our approach allows for the extraction of over 47,000 crystallization conditions from the PDB. Initially, the selected conditions were investigated to determine which carboxylic acids or their salts are most often present in crystallization solutions. From this group, selected sets of crystallization conditions were analyzed in detail, assessing parameters such as concentration, pH, and precipitant used. Our findings will lead to the design of new crystallization screens focused around carboxylic acids.

Biosynthesis of quinoxaline antibiotics: Purification and characterization of the quinoxaline-2-carboxylic acid activating enzyme from Streptomyces triostinicus

International Nuclear Information System (INIS)

Glund, K.; Schlumbohm, W.; Bapat, M.; Keller, U.

1990-01-01

A quinoxaline-2-carboxylic acid activating enzyme was purified to homogeneity from triostin-producing Streptomyces triostinicus. It could also be purified from quinomycin-producing Streptomyces echinatus. Triostins and quinomycins are peptide lactones that contain quinoxaline-2-carboxylic acid as chromophoric moiety. The enzyme catalyzes the ATP-pyrophosphate exchange reaction dependent on quinoxaline-2-carboxylic acid and the formation of the corresponding adenylate. Besides quinoxaline-2-carboxylic acid, the enzyme also catalyzes the formation of adenylates from quinoline-2-carboxylic acid and thieno[3,2-b]pyridine-5-carboxylic acid. No adenylates were seen from quinoline-3-carboxylic acid, quinoline-4-carboxylic acid, pyridine-2-carboxylic acid, and 2-pyrazinecarboxylic acid. Previous work revealed that quinoline-2-carboxylic acid and thieno[3,2-b]pyridine-5-carboxylic acid became efficiently incorporated into the corresponding quinoxaline antibiotic analogues in vivo. Together with the data described here, this suggests that the enzyme is part of the quinoxaline antibiotics synthesizing enzyme system. The enzyme displays a native molecular weight of 42,000, whereas in its denatured form it is a polypeptide of Mr 52,000-53,000. It resembles in its behavior actinomycin synthetase I, the chromophore activating enzyme involved in actinomycin biosynthesis

Molecular Design of a Chiral Brønsted Acid with Two Different Acidic Sites: Regio-, Diastereo-, and Enantioselective Hetero-Diels-Alder Reaction of Azopyridinecarboxylate with Amidodienes Catalyzed by Chiral Carboxylic Acid-Monophosphoric Acid.

Science.gov (United States)

Momiyama, Norie; Tabuse, Hideaki; Noda, Hirofumi; Yamanaka, Masahiro; Fujinami, Takeshi; Yamanishi, Katsunori; Izumiseki, Atsuto; Funayama, Kosuke; Egawa, Fuyuki; Okada, Shino; Adachi, Hiroaki; Terada, Masahiro

2016-09-07

A chiral Brønsted acid containing two different acidic sites, chiral carboxylic acid-monophosphoric acid 1a, was designed to be a new and effective concept in catalytic asymmetric hetero-Diels-Alder reactions of azopyridinecarboxylate with amidodienes. The multipoint hydrogen-bonding interactions among the carboxylic acid, monophosphoric acid, azopyridinecarboxylate, and amidodiene achieved high catalytic and chiral efficiency, producing substituted 1,2,3,6-tetrahydropyridazines with excellent stereocontrol in a single step. This constitutes the first example of regio-, diastereo-, and enantioselective azo-hetero-Diels-Alder reactions by chiral Brønsted acid catalysis.

Substituted Amides of Pyrazine-2-carboxylic acids: Synthesis and Biological Activity

Directory of Open Access Journals (Sweden)

Katarina Kralova

2002-03-01

Full Text Available Condensation of 6-chloro-, 5-tert-butyl- or 6-chloro-5-tert-butylpyrazine-2-carboxylic acid chloride with ring substituted anilines yielded a series of amides, which were tested for their in vitro antimycobacterial, antifungal and photosynthesis-inhibiting activities. The highest antituberculotic activity (72% inhibition against Mycobacterium tuberculosis and the highest lipophilicity (log P = 6.85 were shown by the 3,5-bistrifluoromethylphenyl amide of 5-tert-butyl-6-chloropyrazine-2-carboxylic acid (2o. The 3-methylphenyl amides of 6-chloro- and 5-tert-butyl-6-chloro-pyrazine-2-carboxylic acid (2d and 2f exhibited only a poor in vitro antifungal effect (MIC = 31.25-500 μmol·dm-3 against all strains tested, although the latter was the most active antialgal compound (IC50 = 0.063 mmol·dm-3. The most active inhibitor of oxygen evolution rate in spinach chloroplasts was the (3,5-bis-trifluoromethylphenylamide of 6-chloropyrazine-2-carboxylic acid (2m, IC50 = 0.026 mmol·dm-3.

ON THE FORMATION OF BENZOIC ACID AND HIGHER-ORDER BENZENE CARBOXYLIC ACIDS IN INTERSTELLAR MODEL ICE GRAINS

Energy Technology Data Exchange (ETDEWEB)

McMurtry, Brandon M.; Saito, Sean E. J.; Turner, Andrew M.; Chakravarty, Harish K.; Kaiser, Ralf I. [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

2016-11-10

With a binary ice mixture of benzene (C{sub 6}H{sub 6}) and carbon dioxide (CO{sub 2}) at 10 K under contamination-free ultrahigh vacuum conditions, the formation of benzene carboxylic acids in interstellar ice grains was studied. Fourier transform infrared spectroscopy was used to probe for the formation of new species during the chemical processing of the ice mixture and during the following temperature-programmed desorption. Newly formed benzene carboxylic acid species, i.e., benzoic acid, as well as meta - and para -benzene dicarboxylic acid, were assigned using newly emerging bands in the infrared spectrum; a reaction mechanism, along with rate constants, was proposed utilizing the kinetic fitting of the coupled differential equations.

Anaerobic Fermentation for Production of Carboxylic Acids as Bulk Chemicals from Renewable Biomass.

Science.gov (United States)

Wang, Jufang; Lin, Meng; Xu, Mengmeng; Yang, Shang-Tian

Biomass represents an abundant carbon-neutral renewable resource which can be converted to bulk chemicals to replace petrochemicals. Carboxylic acids have wide applications in the chemical, food, and pharmaceutical industries. This chapter provides an overview of recent advances and challenges in the industrial production of various types of carboxylic acids, including short-chain fatty acids (acetic, propionic, butyric), hydroxy acids (lactic, 3-hydroxypropionic), dicarboxylic acids (succinic, malic, fumaric, itaconic, adipic, muconic, glucaric), and others (acrylic, citric, gluconic, pyruvic) by anaerobic fermentation. For economic production of these carboxylic acids as bulk chemicals, the fermentation process must have a sufficiently high product titer, productivity and yield, and low impurity acid byproducts to compete with their petrochemical counterparts. System metabolic engineering offers the tools needed to develop novel strains that can meet these process requirements for converting biomass feedstock to the desirable product.

Dimerization of Carboxylic Acids: An Equation of State Approach

DEFF Research Database (Denmark)

Tsivintzelis, Ioannis; Kontogeorgis, Georgios; Panayiotou, Costas

2017-01-01

The association term of the nonrandom hydrogen bonding theory, which is an equation of state model, is extended to describe the dimerization of carboxylic acids in binary mixtures with inert solvents and in systems of two different acids. Subsequently, the model is applied to describe the excess...

Enhanced detection of amino acids in hydrophilic interaction chromatography electrospray tandem mass spectrometry with carboxylic acids as mobile phase additives.

Science.gov (United States)

Yin, Dengyang; Hu, Xunxiu; Liu, Dantong; Du, Wencheng; Wang, Haibo; Guo, Mengzhe; Tang, Daoquan

2017-06-01

Liquid chromatography coupled with mass spectrometry technique has been widely used in the analysis of biological targets such as amino acids, peptides, and proteins. In this work, eight common single carboxylic acids or diacids, which contain different pKa have been investigated as the additives to the analysis of amino acids. As the results, carboxylic acid additive can improve the signal intensity of acidity amino acids such as Asp and Glu and the chromatographic separation of basic amino acids such as Arg, His, and Lys. In particular, the diacids have better performance than single acids. The proposed mechanism is that the diacid has hydrogen bond interaction with amino acids to reduce their polarity/amphiprotic characteristics. Besides, oxalic acid has been found having better enhancement than phthalic acid by overall consideration. Therefore, we successfully quantified the 15 amino acids in Sepia bulk pharmaceutical chemical by using oxalic acid as the additive.

An improved synthesis of carbon-14 labelled carboxylic acids from carbon-14 labelled amino acids

International Nuclear Information System (INIS)

Ramamurthy, T.V.; Ravi, S.; Viswanathan, K.V.

1988-01-01

Various carbon-14 labelled amino acids including the aromatic ones viz., tyrosine, phenylalanine and tryptophan are converted to the corresponding carboxylic acids in high yield (70-90%) on a micromolar scale synthesis by reaction with hydroxyl-amine-O-sulphonic acid and in a short reaction time. The improvement in yield has been achieved by using aqeuous alcohol as solvent in lieu of water alone as the medium of reaction. (author)

The Conversion of Carboxylic Acids to Ketones: A Repeated Discovery

Science.gov (United States)

Nicholson, John W.; Wilson, Alan

2004-09-01

This article describes the history of the reaction converting carboxylic acids to ketones. The reaction has been rediscovered several times, yet has actually been known for centuries. The best known version of the process is the Dakin West reaction (1928), which applies to α-amino acids and also involves the simultaneous conversion of the amine group to amido functionality. Unlike other examples, this particular reaction has attracted a reasonable amount of attention and it appears to be better known than the conversion of simple carboxylic acids to ketones. However, this reaction was described as long ago as 1612, when Beguin published an account of it in his book, Tyrocinium Chymicum . Since then, many chemists have rediscovered the reaction, apparently independently. One of the earliest modern accounts was by W. H. Perkin, Sr., in 1886, who made various simple ketones by refluxing the appropriate carboxylic acids with base. However, this work has been largely ignored, including by his son, W. H. Perkin, Jr., who used a more complicated base-catalyzed ketonization to prepare small ring compounds in the early years of the 20th century. Other articles detailing the application of ketonization to organic acids are discussed, including our own work, which employed the process to crosslink carboxylated polymers for possible technical application in coatings. Despite its relative obscurity, the reaction was used by Woodward et al. in the total synthesis of strychnine, reported in 1963, and this is discussed in detail at the end of the article. See Featured Molecules .

The effects of borate minerals on the synthesis of nucleic acid bases, amino acids and biogenic carboxylic acids from formamide.

Science.gov (United States)

Saladino, Raffaele; Barontini, Maurizio; Cossetti, Cristina; Di Mauro, Ernesto; Crestini, Claudia

2011-08-01

The thermal condensation of formamide in the presence of mineral borates is reported. The products afforded are precursors of nucleic acids, amino acids derivatives and carboxylic acids. The efficiency and the selectivity of the reaction was studied in relation to the elemental composition of the 18 minerals analyzed. The possibility of synthesizing at the same time building blocks of both genetic and metabolic apparatuses, along with the production of amino acids, highlights the interest of the formamide/borate system in prebiotic chemistry.

Potentiometric studies on mixed-ligand chelates of uranyl ion with carboxylic acid phenolic acids

International Nuclear Information System (INIS)

Bandiwadekar, S.P.; Chavar, A.M.

1988-01-01

Mixed ligand complexes of UO 2 2+ with bidentate carboxylic and phenolic acids have been studied potentiometrically at 30 ± 0.1degC and μ=0.2M (NaClO 4 ). 1:1 and 1:2 complexes of UO 2 2+ with phthalic acid (PTHA), maleic acid (MAE), malonic acid (MAL), quinolinic acid (QA), 5-sulphosalicylic acid (5-SSA), salicylic acid (SA), and only 1:1 complexes in the case of mandelic acid (MAD) have been detected. The formation of 1:1:1 mixed ligand complexes has been inferred from simultaneous equilibria in the present study. The values of ΔlogK, Ksub(DAL), Ksub(2LA) or Ksub(2AL) for the ternary complexes have been calculated. The stabilities of mixed ligand complexes depend on the size of the chelate ring and the stabilities of the binary complexes. (author). 15 refs

Carboxylic acid-functionalized SBA-15 nanorods for gemcitabine delivery

International Nuclear Information System (INIS)

Bahrami, Zohreh; Badiei, Alireza; Ziarani, Ghodsi Mohammadi

2015-01-01

The present study deals with the functionalization of mesoporous silica nanoparticles as drug delivery systems. Mono, di, and tri amino-functionalized SBA-15 nanorods were synthesized by post-grafting method using (3-aminopropyl) triethoxysilane, N-(2-aminoethyl-)3- aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino) ethylamino] propyl trimethoxysilane, respectively. The carboxylic acid derivatives of the amino-functionalized samples were obtained using succinic anhydride. Tminopropyltrimethoxysilanehe obtained modified materials were investigated as matrixes for the anticancer drug (gemcitabine) delivery. The prepared samples were characterized by SAXS, N 2 adsorption/desorption, SEM, transmission electron microscopy, thermogravimetric analysis, and FTIR and UV spectroscopies. The adsorption and release properties of all samples were studied. It was revealed that the adsorption capacity and release behavior of gemcitabine were highly dependent on the type of the introduced functional groups. The carboxylic acid-modified samples have higher loading content, due to the strong interaction with gemcitabine. The maximum content of deposited drug in the modified SBA-15 nanorods is close to 40 wt%. It was found that the surface functionalization leads toward significant decrease of the drug release rate. The carboxylic acid-functionalized samples have slower release rate in contrast with the amino-functionalized samples

In situ Recovery of Bio-Based Carboxylic Acids

Energy Technology Data Exchange (ETDEWEB)

Karp, Eric M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Saboe, Patrick [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Manker, Lorenz [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Michener, William E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Peterson, Darren J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Brandner, David [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Deutch, Stephen P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cywar, Robin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Beckham, Gregg T [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kumar, Manish [Pennsylvania State University

2018-03-16

The economics of chemical and biological processes is often dominated by the expense of downstream product separations from dilute product streams. Continuous separation techniques, such as in situ product recovery (ISPR), are attractive in that they can concentrate products from a reactor and minimize solvent loss, thereby increasing purity and sustainability of the process. In bioprocesses, ISPR can have an additional advantage of increasing productivity by alleviating product inhibition on the microorganism. In this work, we developed a liquid-liquid extraction (LLE)-based ISPR system integrated with downstream distillation to selectively purify free carboxylic acids, which were selected as exemplary bioproducts due to their ability to be produced at industrially relevant titers and productivities. Equilibrium constants for the extraction of carboxylic acids into a phosphine-oxide based organic phase were experimentally determined. Complete recovery of acids from the extractant and recyclability of the organic phase were demonstrated through multiple extraction-distillation cycles. Using these data, an equilibrium model was developed to predict the acid loading in the organic phase as a function of the extraction equilibrium constant, initial aqueous acid concentration, pH, organic to aqueous volume ratio, and temperature. A distillation process model was then used to predict the energy input required to distill neat acid from an organic phase as a function of the acid loading in the organic phase feed. The heat integrated distillation train can achieve neat recovery of acetic acid with an energy input of 2.6 MJ kg-1 of acetic acid. This LLE-based ISPR system integrated with downstream distillation has an estimated carbon footprint of less than 0.36 kg CO2 per kg of acetic acid, and provides a green approach to enable both new industrial bioprocesses, and process intensification of existing industrial operations by (1) increasing the productivity and titer of

Correction: Synthesis of pyrrolidine-3-carboxylic acid derivatives via asymmetric Michael addition reactions of carboxylate-substituted enones.

Science.gov (United States)

Yin, Feng; Garifullina, Ainash; Tanaka, Fujie

2018-04-25

Correction for 'Synthesis of pyrrolidine-3-carboxylic acid derivatives via asymmetric Michael addition reactions of carboxylate-substituted enones' by Feng Yin et al., Org. Biomol. Chem., 2017, 15, 6089-6092.

Modification of polysulfone with pendant carboxylic acid functionality ...

Indian Academy of Sciences (India)

polysulfone (PSF) by in situ generated chloromethyl radical in presence of stannic chloride in tetrachloroethane and .... vert the nitrile group to carboxylic acid was reported (Reddy ..... PEG molecular weight vs rejection at 35 psi pressure.

Ru(II)-Catalyzed Oxidative Heck-Type Olefination of Aromatic Carboxylic Acids with Styrenes through Carboxylate-Assisted C-H Bond Activation.

Science.gov (United States)

Dana, Suman; Mandal, Anup; Sahoo, Harekrishna; Mallik, Sumitava; Grandhi, Gowri Sankar; Baidya, Mahiuddin

2018-02-02

A straightforward synthesis of 2-styrylbenzoic acids from aryl carboxylic acids is disclosed through a carboxylate-assisted coupling under Ru(II) catalysis. This protocol is simple and exhibits broad scope with high tolerance of common organic functional groups, providing good to excellent yields of diverse olefinated products. The efficacy of this protocol has been showcased through sequential syntheses of isochromanone, isocoumarin, and formal synthesis of anacardic acid derivative in good yields.

Carboxylic acid effects on the size and catalytic activity of magnetite nanoparticles.

Science.gov (United States)

Hosseini-Monfared, Hassan; Parchegani, Fatemeh; Alavi, Sohaila

2015-01-01

Magnetite nanoparticles (Fe3O4-NPs) were successfully synthesized in diethylene glycol in the presence of carboxylic acids. They were characterized using XRD, SEM and FTIR. Carboxylic acid plays a critical role in determining the morphology, particle size and size distribution of the resulting particles. The results show that as-prepared magnetite nanoparticles are monodisperse and highly crystalline. The nanoparticles can be easily dispersed in aqueous media and other polar solvents due to coated by a layer of hydrophilic polyol and carboxylic acid ligands in situ. Easily prepared Fe3O4-NPs have been shown to be an active, recyclable, and highly selective catalyst for the epoxidation of cyclic olefins with aqueous 30% H2O2. Copyright © 2014 Elsevier Inc. All rights reserved.

The Defense-Related Isoleucic Acid Differentially Accumulates in Arabidopsis Among Branched-Chain Amino Acid-Related 2-Hydroxy Carboxylic Acids

Directory of Open Access Journals (Sweden)

Rafał P. Maksym

2018-06-01

Full Text Available The branched-chain amino acid (BCAA related 2-hydroxy carboxylic acid isoleucic acid (ILA enhances salicylic acid-mediated pathogen defense in Arabidopsis thaliana. ILA has been identified in A. thaliana as its glucose conjugate correlated with the activity of the small-molecule glucosyltransferase UGT76B1, which can glucosylate both salicylic acid and ILA in vitro. However, endogenous levels of the ILA aglycon have not yet been determined in planta. To quantify ILA as well as the related leucic acid (LA and valic acid (VA in plant extracts, a sensitive method based on the derivatization of small carboxylic acids by silylation and gas chromatography–mass spectrometric analysis was developed. ILA was present in all species tested including several monocotyledonous and dicotyledonous plants as well as broadleaf and coniferous trees, whereas LA and VA were only detectable in a few species. In A. thaliana both ILA and LA were found. However, their levels varied during plant growth and in root vs. leaves. ILA levels were higher in 2-week-old leaves and decreased in older plants, whereas LA exhibited a reverted accumulation pattern. Roots displayed higher ILA and LA levels compared to leaves. ILA was inversely related to UGT76B1 expression level indicating that UGT76B1 glucosylates ILA in planta. In contrast, LA was not affected by the expression of UGT76B1. To address the relation of both 2-hydroxy acids to plant defense, we studied ILA and LA levels upon infection by Pseudomonas syringae. LA abundance remained unaffected, whereas ILA was reduced. This change suggests an ILA-related attenuation of the salicylic acid response. Collectively, the BCAA-related ILA and LA differentially accumulated in Arabidopsis, supporting a specific role and regulation of the defense-modulating small-molecule ILA among these 2-hydroxy acids. The new sensitive method will pave the way to further unravel their role in plants.

Phosphorescent emissions of phosphine copper(I) complexes bearing 8-hydroxyquinoline carboxylic acid analogue ligands

Energy Technology Data Exchange (ETDEWEB)

Małecki, Jan G., E-mail: gmalecki@us.edu.pl [Department of Crystallography, Institute of Chemistry, University of Silesia, Szkolna 9 street, 40-006 Katowice (Poland); Łakomska, Iwona, E-mail: iwolak@chem.umk.pl [Department of Chemistry, Nicolaus Copernicus University, Toruń (Poland); Maroń, Anna [Department of Crystallography, Institute of Chemistry, University of Silesia, Szkolna 9 street, 40-006 Katowice (Poland); Szala, Marcin [Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice (Poland); Fandzloch, Marzena [Department of Chemistry, Nicolaus Copernicus University, Toruń (Poland); Nycz, Jacek E., E-mail: jacek.nycz@us.edu.pl [Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice (Poland)

2015-05-15

The pseudotetrahedral complexes of [Cu(PPh{sub 3}){sub 2}(L)], where L=8-hydroxy-2-methylquinoline-7-carboxylic acid (1), 8-hydroxy-2,5-dimethylquinoline-7-carboxylic acid (2) or 5-chloro-8-hydroxy-2-methylquinoline-7-carboxylic acid (3) have been synthesized and structurally characterized by X-ray crystallography. Their properties have been examined through combinations of IR, NMR, electronic absorption spectroscopy and cyclic voltammetry. The complexes exhibit extraordinary photophysical properties. Complex (1) in solid state exhibits an emission quantum yield of 4.67% and an excited life time of 1.88 ms (frozen DCM solution up to 6.7 ms). When dissolved in a coordinating solvent (acetonitrile) the charge transfer emission was quenched on a microsecond scale. - Highlights: • Synthesis of copper(I) complexes with 8-hydroxyquinoline carboxylic acid ligands. • Very long lived phosphorescent copper(I) complexes. • [Cu(PPh{sub 3}){sub 2}(L)] where L=8-hydroxy-2-methylquinoline-7-carboxylic acid luminesce in the solid state exhibits extremely long lifetime on millisecond scale (1.9 ms). • In frozen MeOH:EtOH solution lifetime increases to 7 ms. • Quantum efficiency equal to 4.7%.

40 CFR 721.2088 - Carboxylic acids, (C6-C9) branched and linear.

Science.gov (United States)

2010-07-01

... linear. 721.2088 Section 721.2088 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.2088 Carboxylic acids, (C6-C9) branched and linear. (a) Chemical... as carboxylic acids, (C6-C9) branched and linear (PMNs P-93-313, 314, 315, and 316) are subject to...

Kinetic studies on the carboxylation of 6-amino-penicillanic acid to 8-hydroxy-penillic acid

DEFF Research Database (Denmark)

Henriksen, Claus Maxel; Holm, SS; Schipper, D.

1997-01-01

The carboxylation in aqueous solution of 6-amino-penicillanic acid (6-APA) to 8-hydroxy-penillic acid (8-HPA) was studied at 25 degrees C and pH 6.5. During sparging with either a citrate buffer or a chemically defined cultivation medium containing 6-APA with mixtures of carbon dioxide and air (2.......7-41% (v/v) CO2), the kinetics for conversion of 6-APA was followed by HPLC. In the citrate buffer 6-APA was converted by two competitive reactions each following first order kinetics with respect to the concentration of 6-APA: 1. carboxylation into 8-HPA; and 2. slow conversion into an unknown compound....... Formation of the unknown compound was not observed in the cultivation medium. The carboxylation of 6-APA was also found to be first order with respect to the concentration of dissolved carbon dioxide. The rate constant for formation of 8-HPA did not differ significantly in the cultivation medium compared...

Silver-Catalyzed Dehydrogenative Synthesis of Carboxylic Acids from Primary Alcohols

DEFF Research Database (Denmark)

Ghalehshahi, Hajar Golshadi; Madsen, Robert

2017-01-01

A simple silver-catalyzed protocol has been developed for the acceptorless dehydrogenation of primary alcohols into carboxylic acids and hydrogen gas. The procedure uses 2.5 % Ag2 CO3 and 2.5-3 equiv of KOH in refluxing mesitylene to afford the potassium carboxylate which is then converted...... into the acid with HCl. The reaction can be applied to a variety of benzylic and aliphatic primary alcohols with alkyl and ether substituents, and in some cases halide, olefin, and ester functionalities are also compatible with the reaction conditions. The dehydrogenation is believed to be catalyzed by silver...

Catalytic conversion of carboxylic acids in bio-oil for liquid hydrocarbons production

International Nuclear Information System (INIS)

Wang, Shurong; Guo, Zuogang; Cai, Qinjie; Guo, Long

2012-01-01

Bio-oil must be upgraded to be suitable for use as a high-grade transport fuel. Crude bio-oil has a high content of carboxylic acids which can cause corrosion, and the high oxygen content of these acids also reduces the oil’s heating value. In this paper, acetic acid and propanoic acid were chosen as the model carboxylic acids in bio-oil. Their behavior in the production of liquid hydrocarbons during a catalytic conversion process was investigated in a micro-fixed bed reactor. The liquid organic phase from this catalytic conversion process mainly consisted of liquid hydrocarbons and phenol derivatives. Under the condition of low Liquid Hourly Space Velocity (LHSV), the liquid organic phase from acetic acid cracking had a selectivity of 22% for liquid hydrocarbons and a selectivity of 65% for phenol derivatives. The composition of the organic products changed considerably with the LHSV increasing to 3 h −1 . The selectivity for liquid hydrocarbons increased up to 52% while that for phenol derivatives decreased to 32%. Propanoic acid performed much better in producing liquid hydrocarbons than acetic acid. Its selectivity for liquid hydrocarbons was as high as 80% at LHSV = 3 h −1 . A mechanism for this catalytic conversion process was proposed according to the analysis of the components in the liquid organic phases. The pathways of the main compounds formation in the liquid organic phases were proposed, and the reason why liquid hydrocarbons were more effectively produced when using propanoic acid rather than acetic acid was also successfully explained. In addition, BET and SEM characterization were used to analyze the catalyst coke deposition. -- Graphical abstract: Display Omitted Highlights: ► High content of carboxylic acids in bio-oil causes its corrosiveness. ► Acetic acid and propanoic acid are two dominant acids in bio-oil. ► Liquid hydrocarbons were produced by cracking of these two dominant acids. ► A mechanism model was proposed to explain

Use of a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin column and propionic acid as an eluent in ion-exclusion/adsorption chromatography of aliphatic carboxylic acids and ethanol in food samples.

Science.gov (United States)

Mori, Masanobu; Hironaga, Takahiro; Kajiwara, Hiroe; Nakatani, Nobutake; Kozaki, Daisuke; Itabashi, Hideyuki; Tanaka, Kazuhiko

2011-01-01

We developed an ion-exclusion/adsorption chromatography (IEAC) method employing a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin (PS-WCX) column with propionic acid as the eluent for the simultaneous determination of multivalent aliphatic carboxylic acids and ethanol in food samples. The PS-WCX column well resolved mono-, di-, and trivalent carboxylic acids in the acidic eluent. Propionic acid as the eluent gave a higher signal-to-noise ratio, and enabled sensitive conductimetric detection of analyte acids. We found the optimal separation condition to be the combination of a PS-WCX column and 20-mM propionic acid. Practical applicability of the developed method was confirmed by using a short precolumn with a strongly acidic cation-exchange resin in the H(+)-form connected before the separation column; this was to remove cations from food samples by converting them to hydrogen ions. Consequently, common carboxylic acids and ethanol in beer, wine, and soy sauce were successfully separated by the developed method.

In Vitro Reactivity of Carboxylic Acid-CoA Thioesters with Glutathione

DEFF Research Database (Denmark)

Sidenius, Ulrik; Skonberg, Christian; Olsen, Jørgen

2004-01-01

was to investigate whether a correlation could be found between the structure of acyl-CoA thioesters and their reactivities toward the tripeptide, glutathione (ç- Glu-Cys-Gly).  The  acyl-CoA  thioesters  of  eight  carboxylic  acids  (ibuprofen,  clofibric  acid, indomethacin,  fenbufen,  tolmetin,  salicylic  acid......The chemical reactivity of acyl-CoA thioesters toward nucleophiles has been demonstrated in several recent studies. Thus, intracellularly formed acyl-CoAs of xenobiotic carboxylic acids may react covalently with endogenous proteins and potentially lead to adverse effects. The purpose of this study......,  2-phenoxypropionic  acid,  and  (4-chloro-2-methyl-phenoxy)acetic  acid  (MCPA))  were  synthesized,  and  each  acyl-CoA  (0.5  mM)  was incubated with glutathione (5.0 mM) in 0.1 M potassium phosphate (pH 7.4, 37 °C). All of the acyl-CoAs reacted with glutathione to form the respective acyl...

Synthesis of 2-phenyl- and 2,3-diphenyl-quinolin-4-carboxylic acid derivatives

International Nuclear Information System (INIS)

Elhadi, S. A.

2004-09-01

Quinolin derivatives are a group of compounds known to possess a wide range of biological activities. The chemistry of quinolines together with their corresponding aldehydes were dealt with in chapter one of this study. Special emphasis was given to the chemistry of benzaldehyde. Twenty five 2-phenyl- and 2,3-diphenyl-quinolin-4-carboxylic acid derivatives together with their corresponding intermediates were prepared in this work. Basically, the synthetic design of these compounds arise from the appropriate disconnections of the target 2-phenyl and 2,3-diphenyl-quinolin-4-carboxylic acids. The retro synthesis analysis of these compounds reveals pyruvic acid, aromatic amine and benzaldehyde or phenyl pyruvic acid, aromatic amine and benzaldehyde as possible logical precursors for 2-phenyl-and 2,3-diphenyl- quinoline-4-carboxylic acids respectively. The purity and identities of the synthesized compounds were elucidated through chromatographic and spectroscopic techniques. The compounds were heavily subjected to spectroscopic analysis (UV, IR, GC/MS, 1 H-and 13 C- NMR). The appropriate disconnections and the mechanisms of the corresponding reactions were given and discussed in chapter three. The spectral data were interpreted and correlated with the target structures. The prepared 2-phenyl- and 2,3-diphenyl-quinoline-4-carboxylic acid derivatives were screened for their antibacterial activity. The compounds were tested against the standard bacterial organisms B. subtilis, S. aureus, E. coli and P. vulgaris. Some of these compounds were devoid of antibacterial activity against S. aureus and P. vulgaris, while others showed moderate activity. All of the tested compounds showed an activity against B. subtilis and E. coli. 2,3-diphenyl -6-sulphanilamide-quinolin-4-carboxylic acid showed the highest activity against the four standard tested organisms.(Author)

Synthesis of 2-phenyl- and 2,3-diphenyl-quinolin-4-carboxylic acid derivatives

Energy Technology Data Exchange (ETDEWEB)

Elhadi, S A [Department of Chemistry, Faculty of Education, University of Khartoum, Khartoum (Sudan)

2004-09-01

Quinolin derivatives are a group of compounds known to possess a wide range of biological activities. The chemistry of quinolines together with their corresponding aldehydes were dealt with in chapter one of this study. Special emphasis was given to the chemistry of benzaldehyde. Twenty five 2-phenyl- and 2,3-diphenyl-quinolin-4-carboxylic acid derivatives together with their corresponding intermediates were prepared in this work. Basically, the synthetic design of these compounds arise from the appropriate disconnections of the target 2-phenyl and 2,3-diphenyl-quinolin-4-carboxylic acids. The retro synthesis analysis of these compounds reveals pyruvic acid, aromatic amine and benzaldehyde or phenyl pyruvic acid, aromatic amine and benzaldehyde as possible logical precursors for 2-phenyl-and 2,3-diphenyl- quinoline-4-carboxylic acids respectively. The purity and identities of the synthesized compounds were elucidated through chromatographic and spectroscopic techniques. The compounds were heavily subjected to spectroscopic analysis (UV, IR, GC/MS, {sup 1}H-and {sup 13}C- NMR). The appropriate disconnections and the mechanisms of the corresponding reactions were given and discussed in chapter three. The spectral data were interpreted and correlated with the target structures. The prepared 2-phenyl- and 2,3-diphenyl-quinoline-4-carboxylic acid derivatives were screened for their antibacterial activity. The compounds were tested against the standard bacterial organisms B. subtilis, S. aureus, E. coli and P. vulgaris. Some of these compounds were devoid of antibacterial activity against S. aureus and P. vulgaris, while others showed moderate activity. All of the tested compounds showed an activity against B. subtilis and E. coli. 2,3-diphenyl -6-sulphanilamide-quinolin-4-carboxylic acid showed the highest activity against the four standard tested organisms.(Author)

Chemo-enzymatic epoxidation of olefins by carboxylic acid esters and hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Ruesch gen. Klaas, M.; Warwel, S. [Inst. for Biochemistry and Technology of Lipids, H.P. Kaufmanm-Inst., Federal Centre for Cereal, Potato and Lipid Research, Muenster (Germany)

1998-12-31

Ethylen and, recently, butadiene can be epoxidized directly with oxygen and for the epoxidation of propylene, the use of heterogeneous transition metals and organic peroxides (Halcon-Process) is the major player. But, beside from those notable exceptions, all other epoxidations, including large ones like the epoxidation of plant oils as PVC-stabilizers (about 200.000 t/year), are carried out with peroxy acids. Because mcpba is far to expensive for most applications, short chain peracids like peracetic acid are used. Being much less stable than mcpba and thus risky handled in large amounts and high concentrations, these peroxy acids were preferably prepared in-situ. However, conventional in-situ formation of peracids has the serious drawback, that a strong acid is necessary to catalyze peroxy acid formation from the carboxylic acid and hydrogen peroxide. The presence of a strong acid in the reaction mixture often results in decreased selectivity because of the formation of undesired by-products by opening of the oxirane ring. Therefore, we propose a new method for epoxidation based on the in-situ preparation of percarboxylic acids from carboxylic acid esters and hydrogen peroxide catalyzed by a commercial, immobilized lipase. (orig.)

Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

African Journals Online (AJOL)

NICO

radiation balance.4,5 Major water-soluble inorganic ions are associated with atmospheric ... molecular weight carboxylic acids in aerosol samples collected from a rural ... include biomass burning, agriculture, livestock and soil dust. Tropical ...

Measuring the concentration of carboxylic acid groups in torrefied spruce wood.

Science.gov (United States)

Khazraie Shoulaifar, Tooran; Demartini, Nikolai; Ivaska, Ari; Fardim, Pedro; Hupa, Mikko

2012-11-01

Torrefaction is moderate thermal treatment (∼200-300°C) to improve the energy density, handling and storage properties of biomass fuels. In biomass, carboxylic sites are partially responsible for its hygroscopic. These sites are degraded to varying extents during torrefaction. In this paper, we apply methylene blue sorption and potentiometric titration to measure the concentration of carboxylic acid groups in spruce wood torrefied for 30min at temperatures between 180 and 300°C. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic acid sites. Thus both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction which provides new information to the chemical changes occurring during torrefaction. Copyright © 2012 Elsevier Ltd. All rights reserved.

Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes

Science.gov (United States)

Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

2013-02-01

The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

A Concise Synthesis and the Antibacterial Activity of 5,6-Dimethoxynaphthalene-2-carboxylic Acid

OpenAIRE

GÖKSU, Süleyman; UĞUZ, Metin Tansu

2014-01-01

5,6-Dimethoxynaphthalene-2-carboxylic acid was synthesized in 7 steps and with an overall yield of 46%. Bromination of 2-naphthol, and methylation with dimethyl sulfate followed by Friedel-Crafts acylation with AcCl gave 2-acetyl-5-bromo-6-methoxynaphthalene. 2-Acetyl-5-bromo-6-methoxynaphthalene was converted to 5-bromo-6- methoxynaphthalene-2-carboxylic acid by a haloform reaction. The esterification of the acid with methanol, methoxylation with NaOCH3 in the presence of CuI and s...

Acid-Base Behavior of Carboxylic Acid Groups Covalently Attached at the Surface of Polyethylene: The Usefulness of Contact Angle in Following the Ionization of Surface Functionality

Science.gov (United States)

1985-08-01

additional check, we converted granular PE-CO 2H to granular PE-CO 2CH3 by acid -catalyzed esterification. This material had no titrable groups. Upon...Task No. NR-631-840 TECHNICAL REPORT NO. 85-1 Acid -Base Behavior of Carboxylic Acid Groups Covalently Attached at the Surface of Polyethylene: The...34I Acid -Base Behavior K-142 ofCarboxylicAcidGroupsAttached...______________________ 12. PERSIIMAL AUTHOR IS) S.R. Holmes-Farly., R.H. Reamey, T.J

Separation and determination of some carboxylic acids by capillary electrophoresis

International Nuclear Information System (INIS)

Sladkov, V.; Fourest, B.

2006-01-01

Separation and determination of some organic acids, mono-carboxylic (formic and acetic), dicarboxylic (oxalic and tartaric), tricarboxylic (citric) acids and aromatic acids (phtalic, benzoic, mellitic and trimellitic), by capillary electrophoresis are reviewed. The method development parameters, such as separation and injection mode, are discussed. Special attention is paid to the comparison of different detection types (spectroscopic and electrochemical). The optimisation of the carrier electrolyte composition (choice of carrier electrolyte, effect of pH, ionic strength, electro-osmotic flow modifier) is treated. Different additives (alkali-earth and transition metal ions, cyclodextrins and alcohol), which are often used for improving organic acid separation, are also considered. (authors)

Separation and determination of some carboxylic acids by capillary electrophoresis

Energy Technology Data Exchange (ETDEWEB)

Sladkov, V.; Fourest, B

2006-07-01

Separation and determination of some organic acids, mono-carboxylic (formic and acetic), dicarboxylic (oxalic and tartaric), tricarboxylic (citric) acids and aromatic acids (phtalic, benzoic, mellitic and trimellitic), by capillary electrophoresis are reviewed. The method development parameters, such as separation and injection mode, are discussed. Special attention is paid to the comparison of different detection types (spectroscopic and electrochemical). The optimisation of the carrier electrolyte composition (choice of carrier electrolyte, effect of pH, ionic strength, electro-osmotic flow modifier) is treated. Different additives (alkali-earth and transition metal ions, cyclodextrins and alcohol), which are often used for improving organic acid separation, are also considered. (authors)

Chemical states of p-boronophenylalanine in aqueous carboxylic acids and polyols

International Nuclear Information System (INIS)

Kobayashi, Mitsue; Kitaoka, Yoshinori

1995-01-01

Chemical states of p-boronophenylalanine were studied by infrared (IR) spectroscopy in aqueous carboxylic acids and in aqueous fructose. For BPA in water, the absorption band due to the B-O stretching of trigonal boron was observed, while that of tetrahedral boron was observed for BPA in aqueous oxalic acid. This means BPA forms a complex of tetrahedral boron with oxalate. It was proved that BPA also formed complexes of tetrahedral boron with citric acid as well as with fructose. No appreciable interaction was detected between BPA and maleic acid. (author)

Supramolecular Coordination Assemblies Constructed From Multifunctional Azole-Containing Carboxylic Acids

Directory of Open Access Journals (Sweden)

Yuheng Deng

2010-05-01

Full Text Available This paper provides a brief review of recent progress in the field of metal coordination polymers assembled from azole-containing carboxylic acids and gives a diagrammatic summary of the diversity of topological structures in the resulting infinite metal-organic coordination networks (MOCNs. Azole-containing carboxylic acids are a favorable kind of multifunctional ligand to construct various metal complexes with isolated complexes and one, two and three dimensional structures, whose isolated complexes are not the focus of this review. An insight into the topology patterns of the infinite coordination polymers is provided. Analyzed topologies are compared with documented topologies and catalogued by the nature of nodes and connectivity pattern. New topologies which are not available from current topology databases are described and demonstrated graphically.

Synthesis and HPLC evaluation of carboxylic acid phases on a hydride surface.

Science.gov (United States)

Pesek, Joseph J; Matyska, Maria T; Gangakhedkar, Surekha; Siddiq, Rukhsana

2006-04-01

Three organic moieties containing carboxylic acid functional groups are attached to a particulate silica surface through silanization/hydrosilation. Two compounds (undecylenic acid and 10-undecynoic acid) have 11 carbon chains and the other is a five-carbon acid (pentenoic acid). Bonding is confirmed through carbon elemental analysis, diffuse reflectance infrared fourier transform spectroscopy, and carbon-13 and silicon-29 CP-MAS NMR spectroscopy. The bonded phases are tested by HPLC using PTH amino acids, nucleic acids, theophylline-related compounds, anilines, benzoic acid compounds, choline, and tobramycin. The latter two compounds are used to investigate the aqueous normal phase properties of the three bonded materials.

Preparation and reactivity of carboxylic acid-terminated boron-doped diamond electrodes

International Nuclear Information System (INIS)

Niedziolka-Joensson, Joanna; Boland, Susan; Leech, Donal; Boukherroub, Rabah; Szunerits, Sabine

2010-01-01

The paper reports on the formation of carboxy-terminated boron-doped diamond (BDD) electrodes. The carboxylic acid termination was prepared in a controlled way by reacting photochemically oxidized BDD with succinic anhydride. The resulting interface was readily employed for the linking of an amine-terminated ligand such as an osmium complex bearing an amine terminal group. The interfaces were characterized using X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). Contact angle measurements were used to follow the changes in surface wetting properties due to surface functionalization. The chemical reactivity of the carboxyl-terminated BDD was investigated by covalent coupling of the acid groups to an amine-terminated osmium complex.

Hepatic Metabolism of Perfluorinated Carboxylic Acids: A Nuclear Magnetic Resonance Investigation in Vivo

Science.gov (United States)

1995-01-17

Reo, C. M. Goecke, L. Narayanan, and B. M. Jarnot. "Effects of Perfluoro-n- octanoic Acid , Perfluoro-n-decanoic Acid , and Clofibrate on Hepatic...SUBTITLE 7C 5. FUNDING NUMBERS" Hepatic Metabolism of Perfluorinated Carboxylic Acids : A Nuclear Magnetic Resonance Investigation in Vivo G-AFOSR-90-0148 6...octanoic acid (PFOA) and perfluoro-n-decanoic acid (PFDA). These Air Force chemicals belong to a class of CU’. compounds known as peroxisome

Biotransformation of fluorophenyl pyridine carboxylic acids by the model fungus Cunninghamella elegans.

Science.gov (United States)

Palmer-Brown, William; Dunne, Brian; Ortin, Yannick; Fox, Mark A; Sandford, Graham; Murphy, Cormac D

2017-09-01

1. Fluorine plays a key role in the design of new drugs and recent FDA approvals included two fluorinated drugs, tedizolid phosphate and vorapaxar, both of which contain the fluorophenyl pyridyl moiety. 2. To investigate the likely phase-I (oxidative) metabolic fate of this group, various fluorinated phenyl pyridine carboxylic acids were incubated with the fungus Cunninghamella elegans, which is an established model of mammalian drug metabolism. 3.  19 F NMR spectroscopy established the degree of biotransformation, which varied depending on the position of fluorine substitution, and gas chromatography-mass spectrometry (GC-MS) identified alcohols and hydroxylated carboxylic acids as metabolites. The hydroxylated metabolites were further structurally characterised by nuclear magnetic resonance spectroscopy (NMR), which demonstrated that hydroxylation occurred on the 4' position; fluorine in that position blocked the hydroxylation. 4. The fluorophenyl pyridine carboxylic acids were not biotransformed by rat liver microsomes and this was a consequence of inhibitory action, and thus, the fungal model was crucial in obtaining metabolites to establish the mechanism of catabolism.

Cloning of phenazine carboxylic acid genes of Fusarium fujikuroi ...

African Journals Online (AJOL)

STORAGESEVER

2010-03-08

Mar 8, 2010 ... genetic modification can improve the efficacy of biological control agents (Van Loon, 1998). Bacterial secondary ... WCS358r was modified to produce the antifungal com- pound phenazine-1-carboxylic acid (PCA) ( ..... control of Rhizoctonia solani in tomato. J. Biotechnol. 6: 115-127. Raaijmakers JM ...

Precipitation stripping of neodymium from carboxylate extractant with aqueous oxalic acid solutions

International Nuclear Information System (INIS)

Konishi, Yasuhiro; Asai, Satoru; Murai, Tetuya

1993-01-01

This paper describes a precipitation stripping method in which neodymium ions are stripped from carboxylate extractant in organic solvent and simultaneously precipitated with aqueous oxalic acid solution. For the single-stage process, a quantitative criterion for precipitating oxalate powders was derived theoretically, and stripping experiments were done under the precipitation conditions. The resultant precipitates were neodymium oxalate, which is completely free from contamination by the carboxylate extractant and the organic solvent. The overall rate of stripping was controlled by the transfer of neodymium carboxylate in the organic solution, indicating that the presence of oxalic acid in the aqueous phase has no effect on the stripping rate. These findings demonstrate the feasibility of combining the conventional stripping and precipitation stages in a solvent extraction process for separation and purification of rare earths

Thermodynamic studies on corrosion inhibition of aqueous solutions of amino/carboxylic acids toward copper by EMF measurement

International Nuclear Information System (INIS)

Spah, Manjula; Spah, Dal Chand; Deshwal, Balraj; Lee, Seungmoon; Chae, Yoon-Keun; Park, Jin Won

2009-01-01

Electromotive force (E) measurements were made on an electrochemical cell [Cu x Hg|CuCl 2 (m) in a solvent S|AgCl-Ag] (where S is a dilute aqueous solution (0.01 m) of amino acid (glycine, alanine, methionine and glutamic acid) or aliphatic carboxylic acid (formic acid, acetic acid, n-butyric acid and glutaric acid)) at 30 deg. C. These measured E values were used to compute the dissociation constants (K 1 and K 2 ) and the degree of dissociation (α 1 and α 2 ) by iterative procedures. The standard cell potential (E o ) and the mean activity coefficient (γ ± ) of CuCl 2 were also determined. The E o data were next used to evaluate the Gibbs energy of transfer (ΔG tr 0 ) of CuCl 2 from water to dilute aqueous solutions of the amino/carboxylic acids. The negative ΔG tr 0 values suggested that these acids act as potential corrosion inhibitors. The magnitudes of ΔG tr 0 values show that the amino acids act as better corrosion inhibitors towards copper than the aliphatic carboxylic acids.

Biological roles and therapeutic potential of hydroxy-carboxylic acid receptors

Directory of Open Access Journals (Sweden)

Kashan eAhmed

2011-10-01

Full Text Available In the recent past, deorphanization studies have described intermediates of energy metabolism to activate G protein-coupled receptors (GPCRs and to thereby regulate metabolic functions. GPR81, GPR109A and GPR109B, formerly known as the nicotinic acid receptor family, are encoded by clustered genes and share a high degree of sequence homology. Recently, hydroxy-carboxylic acids were identified as endogenous ligands of GPR81, GPR109A and GPR109B, and therefore these receptors have been placed into a novel receptor family of hydroxy-carboxylic acid (HCA receptors. The HCA1 receptor (GPR81 is activated by the glycolytic metabolite 2-hydroxy-propionic acid (lactate, the HCA2 receptor is activated by the ketone body 3-hydroxy-butyric acid and the HCA3 receptor (GPR109B is a receptor for the β-oxidation intermediate 3-hydroxy-octanoic acid. While HCA1 and HCA2 receptors are present in most mammalian species, the HCA3 receptor is exclusively found in humans and higher primates. HCA receptors are expressed in adipose tissue and mediate anti-lipolytic effects in adipocytes through Gi-type G-protein-dependent inhibition of adenylyl cyclase. HCA2 and HCA3 inhibit lipolysis during conditions of increased β-oxidation such as prolonged fasting, whereas HCA1 mediates the anti-lipolytic effects of insulin in the fed state. As HCA2 is a receptor for the established anti-dyslipidemic drug nicotinic acid, HCA1 and HCA3 also represent promising drug targets and several synthetic ligands for HCA receptors have been developed. In this article, we will summarize the deorphanization and pharmacological characterization of HCA receptors. Moreover, we will discuss recent progress in elucidating the physiological and pathophysiological role to further evaluate the therapeutic potential of the HCA receptor family for the treatment of metabolic disease.

Heterocycles [h]-Fused Onto 4-Oxoquinoline-3-Carboxylic Acid, Part VIII [1]. Convenient Synthesis and Antimicrobial Properties of Substituted Hexahydro[1,4]diazepino[2,3-h]quinoline-9-carboxylic acid and Its Tetrahydroquino[7,8-b]benzodiazepine Analog

Directory of Open Access Journals (Sweden)

Yusuf M. Al-Hiari

2008-11-01

Full Text Available [1,4]Diazepino[2,3-h]quinolone carboxylic acid 3 and its benzo-homolog tetrahydroquino[7,8-b]benzodiazepine-3-carboxylic acid 5 were prepared via PPAcatalyzed thermal lactamization of the respective 8-amino-7-substituted-1,4-dihydroquinoline-3-carboxylic acid derivatives 8, 10. The latter compounds were obtained by reduction of their 8-nitro-7-substituted-1,4-dihydroquinoline-3-carboxylic acid precursors 7, 9 which, in turn, were prepared by reaction of 7-chloro-1-cyclopropyl-6-fluoro-8-nitro-1,4-dihydroquinoline-3-carboxylic acid (6 with each of β-alanine and anthranilic acid. All intermediates and target compounds were characterized using elemental analysis, NMR, IR and MS spectral data. The prepared targets and the intermediates have shown interesting antibacterial activity mainly against Gram positive strains. In particular, compound 8 showed good activity against S. aureus (MIC = 0.39 μg/mL and B. subtilis (MIC = 0.78 μg/mL. Compounds 5a and 9 have also displayed good antifungal activity against C. albicans (MIC = 1.56 μg/mL and 0.78 μg/mL, respectively. None of the compounds tested showed any anticancer activity against solid breast cancer cell line MCF-7 cells or a human breast adenocarcinoma cell line.

(Liquid + liquid) equilibria measurements for ternary systems (sulfolane + a carboxylic acid + n-heptane) at T = 303.15 K and at 0.1 MPa

International Nuclear Information System (INIS)

Cele, N.P.; Bahadur, I.; Redhi, G.G.; Ebenso, E.E.

2016-01-01

Highlights: • The (liquid + liquid) equilibrium for (sulfolane + a carboxylic acid + heptane) was measured. • Selectivity values for solvent separation efficiency were calculated. • Separation of carboxylic acids from heptane is feasible by extraction. • Three parameter equations have been fitted to the binodal curve data. • The NRTL and UNIQUAC models were used to correlate the experimental data. - Abstract: In the present work, new (liquid + liquid) equilibrium (LLE) values are reported for ternary systems {sulfolane(1) + acetic acid, or propanoic acid, or butanoic acid, or 2-methylpropanoic acid, or pentanoic acid, or 3-methylbutanoic acid (2) + n-heptane (3)} at T = 303.15 K and at p = 0.1 MPa. The mutual solubility of carboxylic acid in sulfolane is dependent on the length and structure of the alkyl chain of the carboxylic acid; it progressively increases with an increase in the alkyl chain of the carboxylic acid. The single phase homogenous region increases as the alkyl chain of the carboxylic acid increases. The n-heptane is most soluble in the carboxylic acid mixtures with long alkyl chain, that is, (3-methylbutanoic acid + sulfolane) and (pentanoic acid + sulfolane) systems and least soluble in the carboxylic acid with short alkyl chain (acetic acid + sulfolane) system. Carboxylic acid together with many other oxygenates and hydrocarbons are produced by SASOL Company in South Africa using the Fischer–Tropsch process. The details about this process are given in introduction section. The NRTL and UNIQUAC models were used to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems. It was found that the NRTL model fits the experimental values significantly better than the UNIQUAC model.

Radiation-initiated emulsion copolymerization of styrene and carboxylic acid monomers

International Nuclear Information System (INIS)

Egusa, S.; Makuuchi, K.

1982-01-01

The emulsion copolymerization of styrene and carboxylic acid monomers such as acrylic, methacrylic, and itaconic acids (AAc, MAAc, IAc) was studied by using 60 Co γ-rays as initiator and sodium dodecylsulfate as emulsifier. The polymerization behavior of these acid monomers was followed by simultaneous conductometric and potentiometric titrations for a latex sample taken in polymerization. The polymerization rate of these acid monomers increases in the following order of hydrophobicity: IAc < AAc < MAAc; this suggests that their polymerization sites are mainly the surface and/or subsurface regions of latex particles. The copolymerization rate of styrene and acid monomer increases with an increase in the acid monomer content for AAc and MAAc, whereas for IAc the rate decreases. The particle sizes determined by the stopped-flow method reveal that this variation of copolymerization rate cannot be explained by the number of growing particles and should be attributed to another factor; for instance, the transfer rate of styrene molecules from oil droplets to growing particles

Formation and High-order Carboxylic Acids (RCOOH) in Interstellar Analogous Ices of Carbon Dioxide (CO2) and Methane(CH4)

Science.gov (United States)

Zhu, Cheng; Turner, Andrew M.; Abplanalp, Matthew J.; Kaiser, Ralf I.

2018-01-01

This laboratory study simulated the abiotic formation of carboxylic acids (RCOOH) in interstellar analogous ices of carbon dioxide (CO2) and methane (CH4) at 10 K upon exposure to energetic electrons. The chemical processing of the ices and the subsequent warm-up phase were monitored online and in situ, exploiting Fourier Transform Infrared Spectrometry and quadrupole mass spectrometry. Characteristic absorptions of functional groups of carboxylic acids (RCOOH) were observed in the infrared spectra of the irradiated ice. Two proposed reaction mechanisms replicated the kinetic profiles of the carboxylic acids along with the decay profile of the precursors during the irradiation via hydrocarbon formation, followed by carboxylation and/or through acetic acid along with mass growth processes of the alkyl chain. Mass spectra recorded during the warm-up phase demonstrated that these acids are distributed from acetic acid (CH3COOH) up to decanoic acid (C9H19COOH). High-dose irradiation studies (91 ± 14 eV) converted low-molecular-weight acids such as acetic acid (CH3COOH) and propionic acid (C2H5COOH) to higher-molecular-weight carboxylic acids, compared to low-dose irradiation studies (18 ± 3 eV). The traces of the {{{H}}}2{{C}}= {{C}}({OH}{)}2+ (m/z = 60) fragment—a link to linear carboxylic acids—implied that higher-order acids (C n H2n+1COOH, n ≥ 5) are likely branched, which correlates with the recent analysis of the structures of the monocarboxylic acids in the Murchison meteorite.

Direct enantioselective conjugate addition of carboxylic acids with chiral lithium amides as traceless auxiliaries.

Science.gov (United States)

Lu, Ping; Jackson, Jeffrey J; Eickhoff, John A; Zakarian, Armen

2015-01-21

Michael addition is a premier synthetic method for carbon-carbon and carbon-heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B.

Are carboxyl groups the most acidic sites in amino acids? Gas-phase acidities, photoelectron spectra, and computations on tyrosine, p-hydroxybenzoic acid, and their conjugate bases.

Science.gov (United States)

Tian, Zhixin; Wang, Xue-Bin; Wang, Lai-Sheng; Kass, Steven R

2009-01-28

Deprotonation of tyrosine in the gas phase was found to occur preferentially at the phenolic site, and the conjugate base consists of a 70:30 mixture of phenoxide and carboxylate anions at equilibrium. This result was established by developing a chemical probe for differentiating these two isomers, and the presence of both ions was confirmed by photoelectron spectroscopy. Equilibrium acidity measurements on tyrosine indicated that deltaG(acid)(o) = 332.5 +/- 1.5 kcal mol(-1) and deltaH(acid)(o) = 340.7 +/- 1.5 kcal mol(-1). Photoelectron spectra yielded adiabatic electron detachment energies of 2.70 +/- 0.05 and 3.55 +/- 0.10 eV for the phenoxide and carboxylate anions, respectively. The H/D exchange behavior of deprotonated tyrosine was examined using three different alcohols (CF3CH2OD, C6H5CH2OD, and CH3CH2OD), and incorporation of up to three deuterium atoms was observed. Two pathways are proposed to account for these results, and all of the experimental findings are supplemented with B3LYP/aug-cc-pVDZ and G3B3 calculations. In addition, it was found that electrospray ionization of tyrosine from a 3:1 (v/v) CH3OH/H2O solution using a commercial source produces a deprotonated [M-H]- anion with the gas-phase equilibrium composition rather than the structure of the ion that exists in aqueous media. Electrospray ionization from acetonitrile, however, leads largely to the liquid-phase (carboxylate) structure. A control molecule, p-hydroxybenzoic acid, was found to behave in a similar manner. Thus, the electrospray conditions that are employed for the analysis of a compound can alter the isomeric composition of the resulting anion.

Edge-carboxylated graphene nanoflakes from nitric acid oxidised arc-discharge material

OpenAIRE

NICOLOSI, VALERIA

2010-01-01

PUBLISHED Graphene nanoflakes (GNFs) with average diameters of 30 nm have been prepared by a single-step oxidation procedure using single-wall carbon nanotube arc-discharge material and nitric acid. The GNFs are predominately single sheets containing a small number of internal defects. The edges are decorated with primarily carboxylic acid groups which allow facile chemical functionalisation and cross-linking of the fragments using multivalent cations

Surface Patterning of Benzene Carboxylic Acids on Graphite: Influence of structure, solvent, and concentration on molecular self-assembly

Science.gov (United States)

Florio, Gina; Stiso, Kimberly; Campanelli, Joseph; Dessources, Kimberly; Folkes, Trudi

2012-02-01

Scanning tunneling microscopy (STM) was used to investigate the molecular self-assembly of four different benzene carboxylic acid derivatives at the liquid/graphite interface: pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid), trimellitic acid (1,2,4-benzenetricarboxylic acid), trimesic acid (1,3,5-benzenetricarboxylic acid), and 1,3,5-benzenetriacetic acid. A range of two dimensional networks are observed that depend sensitively on the number of carboxylic acids present, the nature of the solvent, and the solution concentration. We will describe our recent efforts to determine (a) the preferential two-dimensional structure(s) for each benzene carboxylic acid at the liquid/graphite interface, (b) the thermodynamic and kinetic factors influencing self-assembly (or lack thereof), (c) the role solvent plays in the assembly, (e) the effect of in situ versus ex situ dilution on surface packing density, and (f) the temporal evolution of the self-assembled monolayer. Results of computational analysis of analog molecules and model monolayer films will also be presented to aid assignment of network structures and to provide a qualitative picture of surface adsorption and network formation.

Development of starch biofilms using different carboxylic acids as plasticizers

International Nuclear Information System (INIS)

Cruz, L.C.; Miranda, C.S.; Santos, W.J. dos; Goncalves, A.P.B.; Oliveira, J.C.; Jose, N.M.

2014-01-01

Biodegradable films have become a widely exploited issue among scientists because of their positive environmental impact, besides their potential to promote better food conservation and an increase in shelf life. Starch has been studied in this field due to its availability, low cost and biodegradability. However, starch films tend to be brittle and they need addition of a plasticizer to enable their usage. In this work, starch films were synthesized with different carboxylic acids as plasticizers, aiming to observe the effect of the acids chain size in the final films properties. The acids used were: oxalic, succinic and adipic. The materials were produced by casting and characterized by DSC, TG, DRX e FTIR. It was observed that the acids chain size influenced on the thermal and structural properties of the films. (author)

Quantification of the xylem-to-phloem transfer of amino acids by use of inulin (14C)carboxylic acid as xylem transfer marker

International Nuclear Information System (INIS)

Van Bel, A.J.

1984-01-01

Inulin ( 14 C)carboxylic acid and 14 C-labelled amino acid (α-aminoisobutyric acid (aib) and valine) solutions were introduced into the transpiration stream through the cut stem bases of young (4-12 leaves) tomato plants. Inulin carboxylic acid (inu) was translocated exclusively by the xylem, whereas the amino acid distribution resulted from both xylem and phloem import. Comparison of the distribution of inu and aib permitted a quantitative assessment of the xylem-to-phloem transfer in the stem. Of aib, 20.6% traversed from xylem to phloem in a plant with 12 leaves. The phloem import was not evenly distributed over the leaves and varied from 0% (first five leaves) to 95% (top leaf) of the aib import per leaf. Doubling the flow rates in the xylem reduced the aib supply to 25% in the top leaf and 55% in the next leaf, which reflects a reduced xylem-to-phloem transfer. (author)

Rapid and selective derivatizatin method for the nitrogen-sensitive detection of carboxylic acids in biological fluids prior to gas chromatographic analysis

NARCIS (Netherlands)

Lingeman, H.; Haan, H.B.P.; Hulshoff, A.

1984-01-01

A rapid and selective derivatization procedure is described for the pre-column labelling of carboxylic acids with a nitrogen-containing label. The carboxylic acid function is activated with 2-bromo-1-methylpyridinium iodide and the activated carboxylic acid function reacts with a primary or a

Direct Enantioselective Conjugate Addition of Carboxylic Acids with Chiral Lithium Amides as Traceless Auxiliaries

Science.gov (United States)

2016-01-01

Michael addition is a premier synthetic method for carbon–carbon and carbon–heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B. PMID:25562717

A Novel Approach in Cinnamic Acid Synthesis: Direct Synthesis of Cinnamic Acids from Aromatic Aldehydes and Aliphatic Carboxylic Acids in the Presence of Boron Tribromide

Directory of Open Access Journals (Sweden)

M. Onciu

2005-02-01

Full Text Available Cinnamic acids have been prepared in moderate to high yields by a new direct synthesis using aromatic aldehydes and aliphatic carboxylic acids, in the presence of boron tribromide as reagent, 4-dimethylaminopyridine (4-DMAP and pyridine (Py as bases and N-methyl-2-pyrolidinone (NMP as solvent, at reflux (180-190°C for 8-12 hours.

Kinetic analysis of the reactivity of aliphatic cyclic alcohols and carboxylic acids in the T-for-H exchange reaction

International Nuclear Information System (INIS)

Tamura, Kiyoshi; Imaizumi, Hiroshi; Kano, Naoki

2007-01-01

In order to quantitatively evaluate the influence of tritium ( 3 He or T) on various functional groups in environment, the hydrogen isotope exchange reaction (T-for-H exchange reaction) between tritium-labeled poly-(vinyl alcohol) and each aliphatic cyclic alcohol (or carboxylic acid) has been dynamically observed in the range of 50 to 90degC. Consequently, the activities of the aliphatic cyclic alcohol and carboxylic acid increased with increasing reaction time. Applying in A''-McKay plot method to the observed data, the rate constants (k) for these materials were obtained. Using the k, the relation between the number of carbon atoms in the ring in each alcohol and the reactivity of the alcohol was quantitatively compared. Then, to clarify the effect of relative atomic charge of O atom (connected with the H atom in the hydroxy (or carboxy) group in the material) on the reactivity of the material, the MOPAC method was used. From both the above-mentioned and the obtained previously, the following nine items were found as to aliphatic cyclic alcohols (and carboxylic acids) in the T-for-H exchange reaction. (1) The reactivity of aliphatic cyclic alcohols (and carboxylic acids) depends on the temperature. (2) The reactivity of the cyclic materials decreases with increasing number of carbon atoms in the ring. (3) The reactivity of the aliphatic cyclic carboxylic acid seems to be smaller than that of aliphatic cyclic alcohol, and be larger than that of aliphatic cyclic amine. (4) For aliphatic cyclic alcohols, correlation exists between k and relative atomic charges of O atom obtained by the MOPAC method, but the tendency for aliphatic cyclic carboxylic acid is not clear. (5) As to having the same number of carbon atoms in each ring, the reactivity of the aliphatic cyclic carboxylic acid including the side chain is smaller than of the aliphatic cyclic carboxylic acid including no side chain. (6) The reactivity of aliphatic cyclic carboxylic acid is larger than that of

Facile syntheses of isotope-labeled chiral octahydroindole-2-carboxylic acid and its N-methyl analog

International Nuclear Information System (INIS)

Yinsheng Zhang

2012-01-01

We have synthesized deuterium and carbon-14 labeled enantiomerically pure octahydroindole-2-carboxylic acid (PD0140417), N-methyl octahydroindole-2-carboxylic acid (PD0348183) and their racemic analogs (PD0108405 and PD0338055). [ring-U- 14 C]PD0140417 was prepared from [ring-U- 14 C]benzoic acid in a seven-step synthesis in 6.2% overall radiochemical yield. [ 14 C]PD0348183 was prepared from [ 14 C]BaCO 3 in a five-step synthesis in 16% radiochemical yield. Additionally, [D]PD0108405 and [D]PD0338055 were synthesized by direct platinum-catalyzed hydrogenation with deuterium gas. (author)

Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

African Journals Online (AJOL)

Atmospheric aerosol samples of PM2.5 and PM10 were collected in April–May 2011 from a rural site in Tanzania and analyzed for water-soluble inorganic ions and low molecular weight carboxylic acids using ion chromatography. PM2.5 and PM10 low-volume samplers with quartz fibre filters were deployed and aerosol ...

The investigation of the reactions of some pyrazole-3-carboxylic acids with various diamines and diols

Directory of Open Access Journals (Sweden)

Rahmi Kasımoğulları

2012-06-01

Full Text Available In this study, some new derivatives were synthesized of 4-benzoyl-1-(3-nitrophenyl-5-phenyl-1H-pyrazole-3-carboxylic acid (1 and 4-(ethoxycarbonyl-1-(3-nitrophenyl-5-phenyl-1H-pyrazole-3-carboxylic acid (2 that they were pyrazole carboxylic acid derivatives. Firstly, 1 and 2 reacted with SOCl2 to transform them into acyl chlorides (3, 4. Then various bis-carboxamide derivatives (5–8 were obtained from the reaction of 3 and 4 with various diamines and also a ;#946;-hydroxy ester (9 derivative was obtained from the reaction of 3 with ethylene glycol. The structures of synthesized compounds were elucidated with using FT-IR, 1H NMR, 13C NMR and elemental analysis methods.

Versatile Multicomponent Reaction Macrocycle Synthesis Using α-Isocyano-ω-carboxylic Acids

NARCIS (Netherlands)

Liao, George P; Abdelraheem, Eman M M; Neochoritis, Constantinos G; Kurpiewska, Katarzyna; Kalinowska-Tłuścik, Justyna; McGowan, David C; Dömling, Alexander

2015-01-01

The direct macrocycle synthesis of α-isocyano-ω-carboxylic acids via an Ugi multicomponent reaction is introduced. This multicomponent reaction (MCR) protocol differs by being especially short, convergent, and versatile, giving access to 12-22 membered rings.

Carboxylic acid functionalization of halloysite nanotubes for sustained release of diphenhydramine hydrochloride

Energy Technology Data Exchange (ETDEWEB)

Zargarian, S. Sh.; Haddadi-Asl, V., E-mail: haddadi@aut.ac.ir; Hematpour, H. [Amirkabir University of Technology, Department of Polymer Engineering and Color Technology (Iran, Islamic Republic of)

2015-05-15

Halloysite nanotubes (HNT) (cylindrical shape with external diameter and length in the range of 30–80 nm and 0.2–1 µm, respectively) were functionalized with 3-aminopropyltriethoxysilane (APTES) from hydroxyl groups by a coupling reaction. Subsequently, maleic anhydride was attached to the APTES moieties to yield carboxylic acid-functionalized HNT. Loading and subsequent release of a model drug molecule diphenhydramine hydrochloride (DPH) on modified and unmodified nanotubes were investigated. Morphology of HNT was studied by electron microscopy. Successful attachment of APTES and carboxylic acid groups to halloysite and drug loading were evaluated by Fourier transform infrared spectroscopy. The amount of surface modification and drug adsorption capacity were calculated via thermogravimetric analysis. The ordered crystal structure of loaded drug was evaluated by X-ray diffraction. UV–Visible spectrophotometer was used to study drug release from modified and unmodified samples. Carboxylated halloysite exhibits higher loading capacity and prolonged release of DPH as compared to that of the natural halloysite.

Carboxylic acid functionalization of halloysite nanotubes for sustained release of diphenhydramine hydrochloride

International Nuclear Information System (INIS)

Zargarian, S. Sh.; Haddadi-Asl, V.; Hematpour, H.

2015-01-01

Halloysite nanotubes (HNT) (cylindrical shape with external diameter and length in the range of 30–80 nm and 0.2–1 µm, respectively) were functionalized with 3-aminopropyltriethoxysilane (APTES) from hydroxyl groups by a coupling reaction. Subsequently, maleic anhydride was attached to the APTES moieties to yield carboxylic acid-functionalized HNT. Loading and subsequent release of a model drug molecule diphenhydramine hydrochloride (DPH) on modified and unmodified nanotubes were investigated. Morphology of HNT was studied by electron microscopy. Successful attachment of APTES and carboxylic acid groups to halloysite and drug loading were evaluated by Fourier transform infrared spectroscopy. The amount of surface modification and drug adsorption capacity were calculated via thermogravimetric analysis. The ordered crystal structure of loaded drug was evaluated by X-ray diffraction. UV–Visible spectrophotometer was used to study drug release from modified and unmodified samples. Carboxylated halloysite exhibits higher loading capacity and prolonged release of DPH as compared to that of the natural halloysite

Hepatic Metabolism of Perfluorinated Carboxylic Acids and Polychlorotrifluoroethylene: A Nuclear Magnetic Resonance Investigation in vito

Science.gov (United States)

1994-01-06

L. Narayanan. and B. M. Jamot. ’Effects of Peulluoro-n- octanoic Acid , Perfluoro-n-decanoic Acid , and Clofibrate on Hepatic Phosphorus Metabolism in...pathways and examined the impact of perfluorocarboxylic acid exposure. This investigative strategy will delineate the metabolic effices exerted by...Perfluorinated Carboxylic Acids and Polychlorotrifluoroethylene: A Nuclear Magnetic Resonance Investigation in Vivo Principal Investigator: Nicholas V. Reo

Phosphazene-promoted metal-free ring-opening polymerization of ethylene oxide initiated by carboxylic acid

KAUST Repository

Zhao, Junpeng

2014-03-11

The effectiveness of carboxylic acid as initiator for the anionic ring-opening polymerization of ethylene oxide was investigated with a strong phosphazene base (t-BuP4) used as promoter. Kinetic study showed an induction period, i.e., transformation of carboxylic acid to hydroxyl ester, followed by slow chain growth together with simultaneous and fast end-group transesterification, which led to poly(ethylene oxide) (PEO) consisting of monoester (monohydroxyl), diester, and dihydroxyl species. An appropriate t-BuP4/acid ratio was proven to be essential to achieve better control over the polymerization and low dispersity of PEO. This work provides important information and enriches the toolbox for macromolecular and biomolecular engineering with protic initiating sites. © 2014 American Chemical Society.

RECOVERY OF CARBOXYLIC ACIDS FROM AQUEOUS SOLUTIONS BY LIQUID-LIQUID EXTRACTION WITH A TRIISOOCTYLAMINE DILUENT SYSTEM

Directory of Open Access Journals (Sweden)

G. Malmary

2001-12-01

Full Text Available Tertiary alkylamines in solution with organic diluents are attractive extractants for the recovery of carboxylic acids from dilute aqueous phases. The aim of this study was to investigate the mechanism for extraction of organic acids from water by a long-chain aliphatic tertiary amine. In order to attain this objective, we studied the liquid-liquid equilibria between the triisooctylamine + 1-octanol + n-heptane system as solvent and an aqueous solution of an individual carboxylic acid such as citric, lactic and malic acids. The experiments showed that the partition coefficient for a particular organic acid depends on the kind of solute, notably when the acid concentration in the aqueous phase is low. A mathematical model, where both chemical association and physical distribution are taken into consideration, is proposed. The model suggests that the various complexes obtained between amine and organic acids contribute to the distribution of the solute between the coexisting phases in equilibrium.

Additional Nucleophile-Free FeCl3-Catalyzed Green Deprotection of 2,4-Dimethoxyphenylmethyl-Protected Alcohols and Carboxylic Acids.

Science.gov (United States)

Sawama, Yoshinari; Masuda, Masahiro; Honda, Akie; Yokoyama, Hiroki; Park, Kwihwan; Yasukawa, Naoki; Monguchi, Yasunari; Sajiki, Hironao

2016-01-01

The deprotection of the methoxyphenylmethyl (MPM) ether and ester derivatives can be generally achieved by the combinatorial use of a catalytic Lewis acid and stoichiometric nucleophile. The deprotections of 2,4-dimethoxyphenylmethyl (DMPM)-protected alcohols and carboxylic acids were found to be effectively catalyzed by iron(III) chloride without any additional nucleophile to form the deprotected mother alcohols and carboxylic acids in excellent yields. Since the present deprotection proceeds via the self-assembling mechanism of the 2,4-DMPM protective group itself to give the hardly-soluble resorcinarene derivative as a precipitate, the rigorous purification process by silica-gel column chromatography was unnecessary and the sufficiently-pure alcohols and carboxylic acids were easily obtained in satisfactory yields after simple filtration.

Lipase catalyzed epoxidation of fatty acid methyl esters derived from unsaturated vegetable oils in absence of carboxylic acid.

Science.gov (United States)

Sustaita-Rodríguez, Alejandro; Ramos-Sánchez, Víctor H; Camacho-Dávila, Alejandro A; Zaragoza-Galán, Gerardo; Espinoza-Hicks, José C; Chávez-Flores, David

2018-04-11

Nowadays the industrial chemistry reactions rely on green technologies. Enzymes as lipases are increasing its use in diverse chemical processes. Epoxidized fatty acid methyl esters obtained from transesterification of vegetable oils have recently found applications as polymer plasticizer, agrochemical, cosmetics, pharmaceuticals and food additives. In this research article, grapeseed, avocado and olive oils naturally containing high percents of mono and poly unsaturations were used as starting materials for the production of unsaturated fatty acid methyl esters. The effect of lauric acid as an active oxygen carrier was studied on epoxidation reactions where unsaturated fatty acid methyl esters were converted to epoxy fatty acid methyl esters using immobilized Candida antarctica Lipase type B as catalyst and hydrogen peroxide as oxygen donor at mild temperature and pressure conditions. After this study it was confirmed by 1 H NMR, 13 C NMR and GC-MS that the addition of lauric acid to the enzymatic reaction is unnecessary to transform the alkenes in to epoxides. It was found that quantitative conversions were possible in despite of a carboxylic acid absence.

On the formation of niacin (vitamin B3) and pyridine carboxylic acids in interstellar model ices

Energy Technology Data Exchange (ETDEWEB)

McMurtry, Brandon M.; Turner, Andrew M.; Saito, Sean E.J.; Kaiser, Ralf I. [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822 (United States); Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822 (United States)

2016-06-15

The formation of pyridine carboxylic acids in interstellar ice grains was simulated by electron exposures of binary pyridine (C{sub 5}H{sub 5}N)-carbon dioxide (CO{sub 2}) ice mixtures at 10 K under contamination-free ultrahigh vacuum conditions. Chemical processing of the pristine ice and subsequent warm-up phase was monitored on line and in situ via Fourier transform infrared spectroscopy to probe for the formation of new radiation induced species. In the infrared spectra of the irradiated ice, bands assigned to nicotinic acid (niacin; vitamin B3; m-C{sub 5}H{sub 4}NCOOH) along with 2,3-, 2,5-, 3,4-, and 3,5-pyridine dicarboxylic acid (C{sub 5}H{sub 3}N(COOH){sub 2}) were unambiguously identified along with the hydroxycarbonyl (HOCO) radical. Our study suggests that the reactive pathway responsible for pyridine carboxylic acids formation involves a HOCO intermediate, which forms through the reaction of suprathermal hydrogen ejected from pyridine with carbon dioxide. The newly formed pyridinyl radical may then undergo radical–radical recombination with a hydroxycarbonyl radical to form a pyridine carboxylic acid.

Hepatic Metabolism of Perfluorinated Carboxylic Acids and Polychlorotrifluoroethylene: A Nuclear Magnetic Resonance Investigation in Vivo

Science.gov (United States)

1994-01-05

Goecke, L. Narayanan, and B. M. Jarnot. "Effects of Perfluoro-n- octanoic Acid , Perfluoro-n-decanoic Acid , and Clofibrate on Hepatic Phosphorus L...Carboxylic Acids and 4Polychiorotrifluoroethylene: A Nuclear Magnetic Resonance G-AFOSR-90-0148 Investigation in Vivo ,IIC 6. AUTHOR(S a Nicholas V. Reo...Maxim um 200 words) This report outlines our research progress regarding toxicological investigations of perifluoro- n-octanoic acid (PFOA) and

Solvent-Free Esterification of Carboxylic Acids Using Supported Iron Oxide Nanoparticles as an Efficient and Recoverable Catalyst

Directory of Open Access Journals (Sweden)

Fatemeh Rajabi

2016-07-01

Full Text Available Supported iron oxide nanoparticles on mesoporous materials (FeNP@SBA-15 have been successfully utilized in the esterification of a variety carboxylic acids including aromatic, aliphatic, and long-chain carboxylic acids under convenient reaction conditions. The supported catalyst could be easily recovered after reaction completion and reused several times without any loss in activity after up to 10 runs.

Synthesis of aminocarbonyl N-acylhydrazones by a three-component reaction of isocyanides, hydrazonoyl chlorides, and carboxylic acids.

Science.gov (United States)

Giustiniano, Mariateresa; Meneghetti, Fiorella; Mercalli, Valentina; Varese, Monica; Giustiniano, Francesco; Novellino, Ettore; Tron, Gian Cesare

2014-10-17

A novel one-pot multicomponent synthesis of α-aminocarbonyl N-acylhydrazones starting from readily available hydrazonoyl chlorides, isocyanides, and carboxylic acids is reported. The strategy exploits the ability of the carboxylic acid as a third component to suppress all competing reactions between nitrile imines and isocyanides, channeling the course of the reaction toward the formation of this novel class of compounds.

The effects of solvents and structure on the electronic absorption spectra of the isomeric pyridine carboxylic acid N-oxides

Directory of Open Access Journals (Sweden)

Drmanić Saša Ž.

2013-01-01

Full Text Available The ultraviolet absorption spectra of the carboxyl group of three isomeric pyridine carboxylic acids N-oxides (picolinic acid N-oxide, nicotinic acid N-oxide and isonicotinic acid N-oxide were determined in fourteen solvents in the wavelength range from 200 to 400 nm. The position of the absorption maxima (λmax of the examined acids showed that the ultraviolet absorption maximum wavelengths of picolinic acid N-oxide are the shortest, and those of isonicotinic acid N-oxide acid are the longest. In order to analyze the solvent effect on the obtained absorption spectra, the ultraviolet absorption frequencies of the electronic transitions in the carboxylic group of the examined acids were correlated using a total solvatochromic equation of the form max = v0 + sπ + aα+ bβ, where υmax is the absorption frequency (1/λmax, p is a measure of the solvent polarity, β represents the scale of solvent hydrogen bond acceptor basicities and α represent the scale of solvent hydrogen bond donor acidities. The correlation of the spectroscopic data was carried out by means of multiple linear regression analysis. The solvent effects on the ultraviolet absorption maximums of the examined acids were discussed.

Basicity of carboxylic acids: resonance in the cation and substituent effects

Czech Academy of Sciences Publication Activity Database

Böhm, S.; Exner, Otto

2005-01-01

Roč. 29, - (2005), s. 336-342 ISSN 1144-0546 R&D Projects: GA MŠk(CZ) LN00A032 Institutional research plan: CEZ:AV0Z4055905 Keywords : basicity * carboxylic acids Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.574, year: 2005

Carboxylic acid functional group analysis using constant neutral loss scanning-mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Dron, Julien [Laboratoire de Chimie et Environnement, Marseille Universites (case 29), 3 place Victor Hugo, 13331 Marseille Cedex 3 (France)], E-mail: julien.dron@up.univ-mrs.fr; Eyglunent, Gregory; Temime-Roussel, Brice; Marchand, Nicolas; Wortham, Henri [Laboratoire de Chimie et Environnement, Marseille Universites (case 29), 3 place Victor Hugo, 13331 Marseille Cedex 3 (France)

2007-12-12

The present study describes the development of a new analytical technique for the functional group determination of the carboxylic moiety using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS/MS) operated in the constant neutral loss scanning (CNLS) mode. Carboxylic groups were first derivatized into their corresponding methyl esters by reacting with BF{sub 3}/methanol mix and the reaction mixture was then directly injected into the APCI chamber. The loss of methanol (m/z = 32 amu) resulting from the fragmentation of the protonated methyl esters was then monitored. Applying this method together with a statistical approach to reference mixtures containing 31 different carboxylic acids at randomly calculated concentrations demonstrated its suitability for quantitative functional group measurements with relative standard deviations below 15% and a detection limit of 0.005 mmol L{sup -1}. Its applicability to environmental matrices was also shown through the determination of carboxylic acid concentrations inside atmospheric aerosol samples. To the best of our knowledge, it is the first time that the tandem mass spectrometry was successfully applied to functional group analysis, offering great perspectives in the characterization of complex mixtures which are prevailing in the field of environmental analysis as well as in the understanding of the chemical processes occurring in these matrices.

Carboxylic acid functional group analysis using constant neutral loss scanning-mass spectrometry

International Nuclear Information System (INIS)

Dron, Julien; Eyglunent, Gregory; Temime-Roussel, Brice; Marchand, Nicolas; Wortham, Henri

2007-01-01

The present study describes the development of a new analytical technique for the functional group determination of the carboxylic moiety using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS/MS) operated in the constant neutral loss scanning (CNLS) mode. Carboxylic groups were first derivatized into their corresponding methyl esters by reacting with BF 3 /methanol mix and the reaction mixture was then directly injected into the APCI chamber. The loss of methanol (m/z = 32 amu) resulting from the fragmentation of the protonated methyl esters was then monitored. Applying this method together with a statistical approach to reference mixtures containing 31 different carboxylic acids at randomly calculated concentrations demonstrated its suitability for quantitative functional group measurements with relative standard deviations below 15% and a detection limit of 0.005 mmol L -1 . Its applicability to environmental matrices was also shown through the determination of carboxylic acid concentrations inside atmospheric aerosol samples. To the best of our knowledge, it is the first time that the tandem mass spectrometry was successfully applied to functional group analysis, offering great perspectives in the characterization of complex mixtures which are prevailing in the field of environmental analysis as well as in the understanding of the chemical processes occurring in these matrices

Metal-Catalyzed Intra- and Intermolecular Addition of Carboxylic Acids to Alkynes in Aqueous Media: A Review

Directory of Open Access Journals (Sweden)

Javier Francos

2017-11-01

Full Text Available The metal-catalyzed addition of carboxylic acids to alkynes is a very effective tool for the synthesis of carboxylate-functionalized olefinic compounds in an atom-economical manner. Thus, a large variety of synthetically useful lactones and enol-esters can be accessed through the intra- or intermolecular versions of this process. In order to reduce the environmental impact of these reactions, considerable efforts have been devoted in recent years to the development of catalytic systems able to operate in aqueous media, which represent a real challenge taking into account the tendency of alkynes to undergo hydration in the presence of transition metals. Despite this, different Pd, Pt, Au, Cu and Ru catalysts capable of promoting the intra- and intermolecular addition of carboxylic acids to alkynes in a selective manner in aqueous environments have appeared in the literature. In this review article, an overview of this chemistry is provided. The synthesis of β-oxo esters by catalytic addition of carboxylic acids to terminal propargylic alcohols in water is also discussed.

Aminolysis of resin-bound N-nosylaziridine-2-carboxylic acids

DEFF Research Database (Denmark)

Olsen, Christian A; Christensen, Caspar; Nielsen, Birgitte

2006-01-01

[Structure: see text] Solid-phase synthesis is a rapidly developing area of organic chemistry, of particular importance for medicinal chemistry and chemical biology. Aziridines have previously only rarely been applied in solid-phase synthesis. In the present work, aminolysis of resin-bound, sprin......-loaded N-nitrobenzenesulfonyl-activated aziridine-2-carboxylic acids has been optimized and employed in the synthesis of a number of open-chain and heterocyclic scaffolds, including enantiopure products....

Optimization of polycrystalline platinum catalytic activity opposite to carboxylic acids oxidation

International Nuclear Information System (INIS)

Le Naour, C.; Moisy, P.; Blanc, P.; Madic, C.

1994-01-01

In electro nuclear industry, in the aim to reduce the quantity of wastes coming from the spent fuels reprocessing, the use of reagents as some carboxylic acids is considered: after use, these reagents are completely decomposed in gaseous products, which can be filtered and released in environment

Changes of sour taste and the composition of carboxylic acids induced in brewed coffee by γ-irradiation on green beans and storage of roast beans

International Nuclear Information System (INIS)

Tomoda, Goro; Matsuyama, Jun; Nagano, Akiko; Namatame, Mitsuko; Morita, Yoshiaki.

1980-01-01

Brazil santos green coffee beans were irradiated with 60 Co-γ rays at doses of 0, 0.05, 0.5 and 1.5 Mrad respectively and changes of the composition of carboxylic acids in roast beans were analyzed by means of GLC together with those of the organoleptic properties of roast beans during storage by use of the cup testing. The total acid content immediately after roasting was about 6,000 mg/100 g (roast beans) and the composition of carboxylic acids was as follows. Chlorogenic acid: hydroxy-carboxylic acids: mono-carboxylic acid: others = 73 : 18 : 7 : 2. Fresh coffee flavour was influenced markedly especially in acid taste by both irradiation of γ-rays on green beans and storage of roast beans, because of the change of above acids composition. On γ-ray irradiation, the change of the acid composition were more clear than that of stored roast beans. Therefore, the quality of γ-irradiated coffee beans seems to be closely associated with the ratio of hydroxy-carboxylic acids mg/ monocarboxylic acids mg, but little with total acid content. (author)

Aerosol volatility and enthalpy of sublimation of carboxylic acids.

Science.gov (United States)

Salo, Kent; Jonsson, Asa M; Andersson, Patrik U; Hallquist, Mattias

2010-04-08

The enthalpy of sublimation has been determined for nine carboxylic acids, two cyclic (pinonic and pinic acid) and seven straight-chain dicarboxylic acids (C(4) to C(10)). The enthalpy of sublimation was determined from volatility measurements of nano aerosol particles using a volatility tandem differential mobility analyzer (VTDMA) set-up. Compared to the previous use of a VTDMA, this novel method gives enthalpy of sublimation determined over an extended temperature range (DeltaT approximately 40 K). The determined enthalpy of sublimation for the straight-chain dicarboxylic acids ranged from 96 to 161 kJ mol(-1), and the calculated vapor pressures at 298 K are in the range of 10(-6)-10(-3) Pa. These values indicate that dicarboxylic acids can take part in gas-to-particle partitioning at ambient conditions and may contribute to atmospheric nucleation, even though homogeneous nucleation is unlikely. To obtain consistent results, some experimental complications in producing nanosized crystalline aerosol particles were addressed. It was demonstrated that pinonic acid "used as received" needed a further purification step before being suspended as a nanoparticle aerosol. Furthermore, it was noted from distinct differences in thermal properties that aerosols generated from pimelic acid solutions gave two types of particles. These two types were attributed to crystalline and amorphous configurations, and based on measured thermal properties, the enthalpy of vaporization was 127 kJ mol(-1) and that of sublimation was 161 kJ mol(-1). This paper describes a new method that is complementary to other similar methods and provides an extension of existing experimental data on physical properties of atmospherically relevant compounds.

1-Aminocyclopropane-1-carboxylic acid and abscisic acid during the germination of sugar beet (Beta vulgaris L.): a comparative study of fruits and seeds

Czech Academy of Sciences Publication Activity Database

Hermann, K.; Meinhard, J.; Dobrev, Petre; Linkies, A.; Pešek, Bedřich; Heß, B.; Macháčková, Ivana; Fischer, U.; Leubner-Metzger, G.

2007-01-01

Roč. 58, č. 11 (2007), s. 3047-3060 ISSN 0022-0957 Institutional research plan: CEZ:AV0Z50380511 Keywords : abscisic acid (ABA) * ABA 8'-hydroxylase (CYP707A) * 1-aminocyclopropane-1-carboxylic acid ( ACC ) Subject RIV: EF - Botanics Impact factor: 3.917, year: 2007

Growth kinetics of racemic heptahelicene-2-carboxylic acid nanowires on calcite (104)

Czech Academy of Sciences Publication Activity Database

Einax, M.; Richter, T.; Nimmrich, M.; Rahe, P.; Stará, Irena G.; Starý, Ivo; Kühnle, A.; Maass, P.

2016-01-01

Roč. 145, č. 13 (2016), č. článku 134702. ISSN 0021-9606 Institutional support: RVO:61388963 Keywords : heptahelicene-2-carboxylic acid nanowires * nc-AFM * calcite * growth kinetics Subject RIV: CC - Organic Chemistry Impact factor: 2.965, year: 2016

Ethylene-enhanced catabolism of [14C]indole-3-acetic acid to indole-3-carboxylic acid in citrus leaf tissues

International Nuclear Information System (INIS)

Sagee, O.; Riov, J.; Goren, J.

1990-01-01

Exogenous [ 14 C]indole-3-acetic acid (IAA) is conjugated in citrus (Citrus sinensis) leaf tissues to one major substance which has been identified as indole-3-acetylaspartic acid (IAAsp). Ethylene pretreatment enhanced the catabolism of [ 14 C]IAA to indole-3-carboxylic acid (ICA), which accumulated as glucose esters (ICGlu). Increased formation of ICGlu by ethylene was accompanied by a concomitant decrease in IAAsp formation. IAAsp and ICGlu were identified by combined gas chromatography-mass spectrometry. Formation of ICGlu was dependent on the concentration of ethylene and the duration of the ethylene pretreatment. It is suggested that the catabolism of IAA to ICA may be one of the mechanisms by which ethylene endogenous IAA levels

LIQUID-CHROMATOGRAPHIC ANALYSIS OF CARBOXYLIC-ACIDS USING N-(4-AMINOBUTYL)-N-ETHYLISOLUMINOL AS CHEMILUMINESCENT LABEL - DETERMINATION OF IBUPROFEN IN SALIVA

NARCIS (Netherlands)

STEIJGER, OM; LINGEMAN, H; BRINKMAN, UAT; HOLTHUIS, JJM; SMILDE, AK; DOORNBOS, DA

1993-01-01

N-(4-Aminobutyl)-N-ethylisoluminol was used for labelling of carboxylic acids. The derivatization reaction was carried out with 1-hydroxybenzotriazole as pre-activator of the carboxylic acid function and N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide as the coupling reagent. Optimum conditions for

Liquid chromatographic analysis of carboxylic acids using N-(4-aminobutyl)-N-ethylisoluminol as chemiluminescent label: determination of ibuprofen in saliva

NARCIS (Netherlands)

Steijger, O. M.; Lingeman, H.; Brinkman, U. A.; Holthuis, J. J.; Smilde, A. K.; Doornbos, D. A.

1993-01-01

N-(4-Aminobutyl)-N-ethylisoluminol was used for labelling of carboxylic acids. The derivatization reaction was carried out with 1-hydroxybenzotriazole as pre-activator of the carboxylic acid function and N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide as the coupling reagent. Optimum conditions for

Thermal stability of carboxylic acid functionality in coal; Sekitanchu ni sonzaisuru karubokishiruki no netsubunkai kyodo

Energy Technology Data Exchange (ETDEWEB)

Tsutsumi, Y.; Aida, T. [Kinki University, Osaka (Japan). Faculty of Engineering

1996-10-28

Carboxyl in coal was focused in discussing its pyrolytic behavior while tracking change of its absolute amount relative to the heating temperatures. A total of four kinds of coals, consisting of two kinds brown coals, sub-bituminous coal and bituminous coal were used. Change in the absolute amount of carboxyl due to heating varies with coalification degree. Decomposition starts in the bituminous coal from around 300{degree}C, and is rapidly accelerated when 400{degree}C is exceeded. Carboxyls in brown coals exist two to three times as much as those in bituminous and sub-bituminous coals, of which 40% is decomposed at a temperature as low as about 300{degree}C. Their pyrolytic behavior at temperatures higher than 400{degree}C resembles that of the bituminous coal. Carboxyls consist of those easy to decompose and difficult to decompose. Aromatic and aliphatic carboxylic acids with simple structure are stable at temperatures lower than 300{degree}C, and decompose abruptly from about 400{degree}C, hence their behavior resembles that of carboxyls in bituminous and sub-bituminous coals. Structure of low-temperature decomposing carboxyls in brown coals is not known, but it is assumed that humic acid originated from natural materials remains in the structure. 4 refs., 3 figs., 1 tab.

Do carboximide–carboxylic acid combinations form co-crystals? The role of hydroxyl substitution on the formation of co-crystals and eutectics

Directory of Open Access Journals (Sweden)

Ramanpreet Kaur

2015-05-01

Full Text Available Carboxylic acids, amides and imides are key organic systems which provide understanding of molecular recognition and binding phenomena important in biological and pharmaceutical settings. In this context, studies of their mutual interactions and compatibility through co-crystallization may pave the way for greater understanding and new applications of their combinations. Extensive co-crystallization studies are available for carboxylic acid/amide combinations, but only a few examples of carboxylic acid/imide co-crystals are currently observed in the literature. The non-formation of co-crystals for carboxylic acid/imide combinations has previously been rationalized, based on steric and computed stability factors. In the light of the growing awareness of eutectic mixtures as an alternative outcome in co-crystallization experiments, the nature of various benzoic acid/cyclic imide combinations is established in this paper. Since an additional functional group can provide sites for new intermolecular interactions and, potentially, promote supramolecular growth into a co-crystal, benzoic acids decorated with one or more hydroxyl groups have been systematically screened for co-crystallization with one unsaturated and two saturated cyclic imides. The facile formation of an abundant number of hydroxybenzoic acid/cyclic carboximide co-crystals is reported, including polymorphic and variable stoichiometry co-crystals. In the cases where co-crystals did not form, the combinations are shown invariably to result in eutectics. The presence or absence and geometric disposition of hydroxyl functionality on benzoic acid is thus found to drive the formation of co-crystals or eutectics for the studied carboxylic acid/imide combinations.

[Chloroquine analogues from benzofuro- and benzothieno[3,2-b]-4-pyridone-2-carboxylic acid esters].

Science.gov (United States)

Gölitzer, K; Meyer, H; Jomaa, H; Wiesner, J

2004-08-01

The amides 7 were synthesized from the annulated methyl 4-pyridone-2-carboxylates 4 via the carboxylic acids 5 and their acid chlorides by reacting with the novaldiamine base 6. The alcohol 8b, obtained from DIBAH reduction of the ester 4b, was transformed to the chloromethyl derivative 9 which reacted with 6 and 18-crown-6 leading to the 2-novaldiaminomethyl-4-pyridone 10. Compound 10 was obtained with higher yield from DIBAH reduction of the amide 7b. The substances 7 and 10 were inactive when tested against the chloroquine resistant Plasmodium falciparum strain Dd2.

Recovery of carboxylic acids at pH greater than pK_a

Energy Technology Data Exchange (ETDEWEB)

Tung, Lisa A. [Univ. of California, Berkeley, CA (United States)

1993-08-01

Economics of producing carboxylic acids by fermentation is often dominated, not by the fermentation cost, but by the cost of recovering and purifying the acids from dilute aqueous solutions. Experiments were performed to measure uptakes of lactic and succinic acids as functions of pH by basic polymeric sorbents; sorbent regeneration was also tested. Performance at pH > pK_a and regenerability depend on sorbent basicity; apparent pK_a and monomer pK{sub a} can be used to predict sorbent performance. Two basic amine extractants, Alamine 336 and Amberlite LA-2, in were also studied; they are able to sustain capacity to higher pH in diluents that stabilize the acid-amine complex through H bonding. Secondary amines perform better than tert-amines in diluents that solvate the additional proton. Competitive sulfate and phosphate, an interference in fermentation, are taken up by sorbents more strongly than by extractants. The third step in the proposed fermentation process, the cracking of the trimethylammonium (TMA) carboxylate, was also examined. Because lactic acid is more soluble and tends to self-esterify, simple thermal cracking does not remove all TMA; a more promising approach is to esterify the TMA lactate by reaction with an alcohol.

Organocatalyzed, Visible-Light Photoredox-Mediated, One-Pot Minisci Reaction Using Carboxylic Acids via N-(Acyloxy)phthalimides.

Science.gov (United States)

Sherwood, Trevor C; Li, Ning; Yazdani, Aliza N; Dhar, T G Murali

2018-03-02

An improved, one-pot Minisci reaction has been developed using visible light, an organic photocatalyst, and carboxylic acids as radical precursors via the intermediacy of in situ-generated N-(acyloxy)phthalimides. The conditions employed are mild, demonstrate a high degree of functional group tolerance, and do not require a large excess of the carboxylic acid reactant. As a result, this reaction can be applied to drug-like scaffolds and molecules with sensitive functional groups, enabling late-stage functionalization, which is of high interest to medicinal chemistry.

Anti-Inflammatory and Antinociceptive Activities of Anthraquinone-2-Carboxylic Acid.

Science.gov (United States)

Park, Jae Gwang; Kim, Seung Cheol; Kim, Yun Hwan; Yang, Woo Seok; Kim, Yong; Hong, Sungyoul; Kim, Kyung-Hee; Yoo, Byong Chul; Kim, Shi Hyung; Kim, Jong-Hoon; Cho, Jae Youl

2016-01-01

Anthraquinone compounds are one of the abundant polyphenols found in fruits, vegetables, and herbs. However, the in vivo anti-inflammatory activity and molecular mechanisms of anthraquinones have not been fully elucidated. We investigated the activity of anthraquinones using acute inflammatory and nociceptive experimental conditions. Anthraquinone-2-carboxylic acid (9,10-dihydro-9,10-dioxo-2-anthracenecarboxylic acid, AQCA), one of the major anthraquinones identified from Brazilian taheebo, ameliorated various inflammatory and algesic symptoms in EtOH/HCl- and acetylsalicylic acid- (ASA-) induced gastritis, arachidonic acid-induced edema, and acetic acid-induced abdominal writhing without displaying toxic profiles in body and organ weight, gastric irritation, or serum parameters. In addition, AQCA suppressed the expression of inflammatory genes such as cyclooxygenase- (COX-) 2 in stomach tissues and lipopolysaccharide- (LPS-) treated RAW264.7 cells. According to reporter gene assay and immunoblotting analyses, AQCA inhibited activation of the nuclear factor- (NF-) κB and activator protein- (AP-) 1 pathways by suppression of upstream signaling involving interleukin-1 receptor-associated kinase 4 (IRAK1), p38, Src, and spleen tyrosine kinase (Syk). Our data strongly suggest that anthraquinones such as AQCA act as potent anti-inflammatory and antinociceptive components in vivo, thus contributing to the immune regulatory role of fruits and herbs.

Phase behavior and micellar properties of carboxylic acid end group modified pluronic surfactants

NARCIS (Netherlands)

Custers, J.P.A.; Broeke, van den L.J.P.; Keurentjes, J.T.F.

2007-01-01

The micellar behavior of three different carboxylic acid end standing (CAE) surfactants has been characterized using conductometry, differential scanning calorimetry, isothermal titration calorimetry, and dynamic light scattering. The CAE surfactants are modified high molecular weight Pluronic

Acid monomer analysis in waterborne polymer systems by targeted labeling of carboxylic acid functionality, followed by pyrolysis - gas chromatography.

Science.gov (United States)

Brooijmans, T; Okhuijsen, R; Oerlemans, I; Schoenmakers, P J; Peters, R

2018-05-14

Pyrolysis - gas chromatography - (PyGC) is a common method to analyse the composition of natural and synthetic resins. The analysis of acid functionality in, for example, waterborne polyacrylates and polyurethanes polymers has proven to be difficult due to solubility issues, inter- and intramolecular interaction effects, lack of detectability in chromatographic analysis, and lack of thermal stability. Conventional analytical techniques, such as PyGC, cannot be used for the direct detection and identification of acidic monomers, due to thermal rearrangements that take place during pyrolysis. To circumvent this, the carboxylic acid groups are protected prior to thermal treatment by reaction with 2-bromoacetophenone. Reaction conditions are investigated and optimised wrt. conversion measurements. The aproach is applied to waterborne polyacryalates and the results are discussed. This approach enables identification and (semi)quantitative analysis of different acid functionalities in waterborne polymers by PyGC. Copyright © 2018 Elsevier B.V. All rights reserved.

Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

Science.gov (United States)

Vaïtilingom, M.; Charbouillot, T.; Deguillaume, L.; Maisonobe, R.; Parazols, M.; Amato, P.; Sancelme, M.; Delort, A.-M.

2011-08-01

The objective of this work was to compare experimentally the contribution of photochemistry vs. microbial activity to the degradation of carboxylic acids present in cloud water. For this, we selected 17 strains representative of the microflora existing in real clouds and worked on two distinct artificial cloud media that reproduce marine and continental cloud chemical composition. Photodegradation experiments with hydrogen peroxide (H2O2) as a source of hydroxyl radicals were performed under the same microcosm conditions using two irradiation systems. Biodegradation and photodegradation rates of acetate, formate, oxalate and succinate were measured on both media at 5 °C and 17 °C and were shown to be on the same order of magnitude (around 10-10-10-11 M s-1). The chemical composition (marine or continental origin) had little influence on photodegradation and biodegradation rates while the temperature shift from 17 °C to 5 °C decreased biodegradation rates of a factor 2 to 5. In order to test other photochemical scenarios, theoretical photodegradation rates were calculated considering hydroxyl (OH) radical concentration values in cloud water estimated by cloud chemistry modelling studies and available reaction rate constants of carboxylic compounds with both hydroxyl and nitrate radicals. Considering high OH concentration ([OH] = 1 × 10-12 M) led to no significant contribution of microbial activity in the destruction of carboxylic acids. On the contrary, for lower OH concentration (at noon, [OH] = 1 × 10-14 M), microorganisms could efficiently compete with photochemistry and in similar contributions than the ones estimated by our experimental approach. Combining these two approaches (experimental and theoretical), our results led to the following conclusions: oxalate was only photodegraded; the photodegradation of formate was usually more efficient than its biodegradation; the biodegradation of acetate and succinate seemed to exceed their photodegradation.

A Precise Method for Processing Data to Determine the Dissociation Constants of Polyhydroxy Carboxylic Acids via Potentiometric Titration.

Science.gov (United States)

Huang, Kaixuan; Xu, Yong; Lu, Wen; Yu, Shiyuan

2017-12-01

The thermodynamic dissociation constants of xylonic acid and gluconic acid were studied via potentiometric methods, and the results were verified using lactic acid, which has a known pKa value, as a model compound. Solutions of xylonic acid and gluconic acid were titrated with a standard solution of sodium hydroxide. The determined pKa data were processed via the method of derivative plots using computer software, and the accuracy was validated using the Gran method. The dissociation constants associated with the carboxylic acid group of xylonic and gluconic acids were determined to be pKa 1  = 3.56 ± 0.07 and pKa 1  = 3.74 ± 0.06, respectively. Further, the experimental data showed that the second deprotonation constants associated with a hydroxyl group of each of the two acids were pKa 2  = 8.58 ± 0.12 and pKa 2  = 7.06 ± 0.08, respectively. The deprotonation behavior of polyhydroxy carboxylic acids was altered using various ratios with Cu(II) to form complexes in solution, and this led to proposing a hypothesis for further study.

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.

Hepatic Metabolism of Perfluorinated Carboxylic Acids and Polycholorotrifluoroethylene: A Nuclear Magnetic Resonance Investigation in Vivo

Science.gov (United States)

1993-01-14

I14JAN93 Annual Technical Report 15DEC91-1ý+JAN9 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Hepatic Metabolism of Perfluorinated Carboxylic Acids and G-FS...13. ABSTRACT (Maximum 200 words) This report describes our studies of the effects of perfluorooctanoic acid (PFOA) and perfluorodecanolc acid (PFDA) on...metabolism. 31 p NMR was used to examine the effects of PFDA. PFOA. and clofibrate (C LOF) in both rats and guinea pigs. A unique effect is revealed in

Use of technical mixtures of carboxylic acids to the extraction of silver

International Nuclear Information System (INIS)

Smulek, W.

1983-01-01

The application of technical mixtures of carboxylic acids, obtained from a Polish oil mill, to the extraction of silver, gold, and europium is described. The distribution ratio is given as a function of HNO 3 and H 2 SO 4 concentrations, extractant and metal concentrations, and nature of diluent. (author)

Synthesis and bioactivities of Phenazine-1-carboxylic acid derivatives based on the modification of PCA carboxyl group.

Science.gov (United States)

Xiong, Zhipeng; Niu, Junfan; Liu, Hao; Xu, Zhihong; Li, Junkai; Wu, Qinglai

2017-05-01

Phenazine-1-carboxylic acid (PCA) as a natural product widely exists in microbial metabolites of Pseudomonads and Streptomycetes and has been registered for the fungicide against rice sheath blight in China. To find higher fungicidal activities compounds and study the effects on fungicidal activities after changing the carboxyl group of PCA, we synthesized a series of PCA derivatives by modifying the carboxyl group of PCA and their structures were confirmed by 1 H NMR and HRMS. Most compounds exhibited significant fungicidal activities in vitro. In particular, compound 6 exhibited inhibition effect against Rhizoctonia solani with EC 50 values of 4.35mg/L and compound 3b exhibited effect against Fusarium graminearum with EC 50 values of 8.30mg/L, compared to the positive control PCA with its EC 50 values of 7.88mg/L (Rhizoctonia solani) and 127.28mg/L (Fusarium graminearum), respectively. The results indicated that the carboxyl group of PCA could be modified to be amide group, acylhydrazine group, ester group, methyl, hydroxymethyl, chloromethyl and ether group etc. And appropriate modifications on carboxyl group of PCA were useful to extend the fungicidal scope. Copyright © 2017 Elsevier Ltd. All rights reserved.

Perfluorinated carboxylic acids in human breast milk from Spain and estimation of infant's daily intake

Energy Technology Data Exchange (ETDEWEB)

Motas Guzmàn, Miguel [Área de Toxicología, Universidad de Murcia, Campus de Espinardo, 30100 Murcia (Spain); Clementini, Chiara [University of Siena, Department of Physical Sciences, Earth and Environment, Via Mattioli, 4, 53100 Siena (Italy); Pérez-Cárceles, Maria Dolores; Jiménez Rejón, Sandra [Department of Legal Medicine, School of Medicine, University of Murcia & Instituto Murciano de Investigacion Biomedica (IMIB), (IMIB-VIRGEN DE LA ARRIXACA), Murcia (Spain); Cascone, Aurora; Martellini, Tania [Department of Chemistry “Ugo Schiff”, via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze (Italy); Guerranti, Cristiana [University of Siena, Department of Physical Sciences, Earth and Environment, Via Mattioli, 4, 53100 Siena (Italy); Bioscience Research Center, Via Aurelia Vecchia 32, 58015 Orbetello, GR (Italy); Cincinelli, Alessandra, E-mail: acincinelli@unifi.it [Department of Chemistry “Ugo Schiff”, via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze (Italy)

2016-02-15

Human milk samples were collected from 67 mothers in 2014 at a Primary Care Centre in Murcia (Spain) and analyzed for perfluorinated carboxylic acids (PFCAs). Concentrations measured for perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA) and perfluorododecanoic acid (PFDoDA) ranged from < LOQ (< 10 ng/L) to 397 ng/L with a mean concentration of 66 ± 68 ng/L and a median of 29 ng/L. The presence of these compounds was revealed in 50 samples out of 67 analyzed. Influence of number of pregnancies and food habits on PFCAs concentrations was also investigated. Statistically significant differences in PFCA levels were found when the women were divided into maternal age classes and into the categories primiparae and multiparae. A greater transfer of PFC during breastfeeding by primiparous was evidenced and thus a higher exposure to these contaminants for the first child. Moreover, it was possible to hypothesize that the content of PFCs is in general correlated to the eating habits of donors and, in particular, with the fish consumption. Finally, PFOA daily intakes and risk index (RI) were estimated for the first six months of life and we found that ingestion rates of PFOA did not exceed the tolerable daily intake (TDI) recommended by the European Food Safety Authority (EFSA). - Graphical abstract: Figure SI 1. Concentrations (ng/L) of PFCs recovered in 67 samples of human breast milk. - Highlights: • Perfluorinated carboxylic acids were analyzed in a set of 67 breast milk samples collected from Spanish women. • PFOA appeared as the major contributor to the total perfluorinated carboxylic acids. • PFOA concentrations were significantly higher in milk of primiparous participants. • PFOA daily intake and risk index were estimated for the firsts six month of life.

Perfluorinated carboxylic acids in human breast milk from Spain and estimation of infant's daily intake

International Nuclear Information System (INIS)

Motas Guzmàn, Miguel; Clementini, Chiara; Pérez-Cárceles, Maria Dolores; Jiménez Rejón, Sandra; Cascone, Aurora; Martellini, Tania; Guerranti, Cristiana; Cincinelli, Alessandra

2016-01-01

Human milk samples were collected from 67 mothers in 2014 at a Primary Care Centre in Murcia (Spain) and analyzed for perfluorinated carboxylic acids (PFCAs). Concentrations measured for perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA) and perfluorododecanoic acid (PFDoDA) ranged from < LOQ (< 10 ng/L) to 397 ng/L with a mean concentration of 66 ± 68 ng/L and a median of 29 ng/L. The presence of these compounds was revealed in 50 samples out of 67 analyzed. Influence of number of pregnancies and food habits on PFCAs concentrations was also investigated. Statistically significant differences in PFCA levels were found when the women were divided into maternal age classes and into the categories primiparae and multiparae. A greater transfer of PFC during breastfeeding by primiparous was evidenced and thus a higher exposure to these contaminants for the first child. Moreover, it was possible to hypothesize that the content of PFCs is in general correlated to the eating habits of donors and, in particular, with the fish consumption. Finally, PFOA daily intakes and risk index (RI) were estimated for the first six months of life and we found that ingestion rates of PFOA did not exceed the tolerable daily intake (TDI) recommended by the European Food Safety Authority (EFSA). - Graphical abstract: Figure SI 1. Concentrations (ng/L) of PFCs recovered in 67 samples of human breast milk. - Highlights: • Perfluorinated carboxylic acids were analyzed in a set of 67 breast milk samples collected from Spanish women. • PFOA appeared as the major contributor to the total perfluorinated carboxylic acids. • PFOA concentrations were significantly higher in milk of primiparous participants. • PFOA daily intake and risk index were estimated for the firsts six month of life.

Corrosion of stainless steel in alcohol solutions of the simplest carboxylic acids

International Nuclear Information System (INIS)

Vigdorovich, V.I.; Korneeva, T.V.; Tsygankova, L.E.

1975-01-01

The behaviour of stainless Kh18N10T steel is considered in the methanol and ethanol solutions of formic and acetic acids, respectively. Consideration is given to the effect of the concentration (C) of the acid (0.01-1.00 N), water (0.1-20.0 mass.%) and temperature (room temperature, 40 and 60 deg C). Curves of anodic polarization were plotted. In the course of time in 1.0 and 0.5 N anhydrous methanol solutions of HCOOH at room temperature in the absence of the external anode current one can observe an increase in the electrode potential. Continued reduction of the formic acid concentration results in an improvement on the initial potential (psi) and a practical constancy of psi in time. It is shown that depending on the acid concentration the additions of water are capable of producing both a passivating and an activating effect. It is assumed that the growth in the length of the hydrocarbon radical of carboxylic acid promotes the adsorption displacement of water and alcohols from the metal surface and enhancement of the corrosion rate

An acridinium sulphonylamide as a new chemiluminescent label for the determination of carboxylic acids in liquid chromatography

NARCIS (Netherlands)

Steijger, O.M.; Kamminga, D.A.; Lingeman, H.; Brinkman, U.A.T.

1998-01-01

The synthesis of a new acridinium sulphonylamide label for the liquid chromatographic determination of carboxylic acids is described. The label 10-methyl-N-(p-tolyl)-N-(p-iodoacetamidobenzenesulphonyl)-9-acridinium carboxamide iodide is synthesized from 9-acridinecarboxylic acid by a seven-step

Omega-3 carboxylic acids monotherapy and combination with statins in the management of dyslipidemia

Directory of Open Access Journals (Sweden)

Benes LB

2016-12-01

Full Text Available Lane B Benes1, Nikhil S Bassi2, Michael H Davidson1 1Department of Medicine, Section of Cardiology, 2Department of Medicine, University of Chicago, Chicago, IL, USA Abstract: The 2013 American College of Cardiology/American Heart Association guidelines on cholesterol management placed greater emphasis on statin therapy given the well-established benefits in primary and secondary prevention of cardiovascular disease. Residual risk may remain after statin initiation, in part because of triglyceride-rich lipoprotein cholesterol. Several large trials have failed to show benefit with non-statin cholesterol-lowering medications in the reduction of cardiovascular events. Yet, subgroup analyses showed a benefit in those with hypertriglyceridemia and lower high-density lipoprotein cholesterol level, a high-risk pattern of dyslipidemia. This review discusses the benefits of omega-3 carboxylic acids, a recently approved formulation of omega-3 fatty acid with enhanced bioavailability, in the treatment of dyslipidemia both as monotherapy and combination therapy with a statin. Keywords: omega-3 carboxylic acids, non-HDL-C, hypertriglyceridemia, residual risk, statin

Ultrasonic-assisted preparation of graphene oxide carboxylic acid polyvinyl alcohol polymer film and studies of thermal stability and surface resistivity.

Science.gov (United States)

Li, Yongshen; Li, Jihui; Li, Yuehai; Li, Yali; Song, Yunan; Niu, Shuai; Li, Ning

2018-01-01

In this paper, flake graphite, nitric acid and acetic anhydride are used to prepare graphene oxide carboxylic acid (GO-COOH) via an ultrasonic-assisted method, and GO-COOH and polyvinyl alcohol polymer (PVA) are used to synthesize graphene oxide carboxylic acid polyvinyl alcohol polymer (GO-COOPVA) via the ultrasonic-assisted method, and GO-COOPVA is used to manufacture graphene oxide carboxylic acid polyvinyl alcohol polymer film (GO-COOPVA film) via a solidification method, and the structure and morphology of GO-COOH, GO-COOPVA and GO-COOPVA film are characterized, and the thermal stability and surface resistivity are measured in the case of the different amount of GO-COOH. Based on the characterization and measurement, it has been successively confirmed and attested that carboxyl groups implant on 2D lattice of GO to form GO-COOH, and GO-COOH and PVA have the esterification reaction to produce GO-COOPVA, and GO-COOPVA consists of 2D lattice of GO-COOH and the chain of PVA connected in the form of carboxylic ester, and GO-COOPVA film is composed of GO-COOPVA, and the thermal stability of GO-COOPVA film obviously improves in comparison with PVA film, and the surface resistivity of GO-COOPVA film clearly decreases. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparative in vitro toxicity assessment of perfluorinated carboxylic acids.

Science.gov (United States)

Mahapatra, Cecon T; Damayanti, Nur P; Guffey, Samuel C; Serafin, Jennifer S; Irudayaraj, Joseph; Sepúlveda, Maria S

2017-06-01

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are synthetic fluorinated compounds that are highly bioaccumulative and persistent organic pollutants. Perfluorooctanoic acid (PFOA), an eight-carbon chain perfluorinated carboxylic acid, was used heavily for the production of fluoropolymers, but concerns have led to its replacement by shorter carbon chain homologues such as perfluorohexanoic acid (PFHxA) and perfluorobutanoic acid (PFBA). However, limited toxicity data exist for these substitutes. We evaluated the toxicity of PFOA, PFHxA and PFBA on a zebrafish liver cell line and investigated the effects of exposure on cell metabolism. Gross toxicity after 96 h of exposure was highest for PFOA and PFO - , while PFHxA and PFBA exhibited lower toxicity. Although the structural similarity of these compounds to fatty acids suggests the possibility of interference with the transport and metabolism of lipids, we could not detect any differential expression of peroxisome proliferator-activated receptor (ppar-α, -β and -γ), fabp3 and crot genes after 96 h exposure to up to 10 ppm of the test compounds. However, we observed localized lipid droplet accumulation only in PFBA-exposed cells. To study the effects of these compounds on cell metabolism, we conducted fluorescence lifetime imaging microscopy using naturally fluorescent biomarkers, NADH and FAD. The fluorescence lifetimes of NADH and FAD and the bound/free ratio of each of these coenzymes decreased in a dose- and carbon length-dependent manner, suggesting disruption of cell metabolism. In sum, our study revealed that PFASs with shorter carbon chains are less toxic than PFOA, and that exposure to sublethal dosage of PFOA, PFHxA or PFBA affects cell metabolism. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Synthesis of carboxylic acids, esters, alcohols and ethers containing a tetrahydropyran ring derived from 6-methyl-5-hepten-2-one.

Science.gov (United States)

Hanzawa, Yohko; Hashimoto, Kahoko; Kasashima, Yoshio; Takahashi, Yoshiko; Mino, Takashi; Sakamoto, Masami; Fujita, Tsutomu

2012-01-01

3-hydroxy acids, 3-hydroxy-3,7-dimethyloct-6-enoic acid (1) and 3-hydroxy-2,2,3,7-tetramethyloct-6-enoic acid (2), were prepared from 6-methyl-5-hepten-2-one, and they were subsequently used to prepare (2,6,6-trimethyltetrahydropyran-2-yl)acetic acid (3) and 2-methyl-2-(2,6,6-trimethyltetrahydropyran-2-yl)propanoic acid (4), respectively, via cyclization with an acidic catalyst such as boron trifluoride diethyl etherate or iodine. The reaction of carboxylic acids 3 and 4 with alcohols, including methanol, ethanol, and 1-propanol, produced the corresponding methyl, ethyl, and propyl esters, which all contained a tetrahydropyran ring. Reduction of carboxylic acids 3 and 4 afforded the corresponding alcohols. Subsequent reactions of these alcohols with several acyl chlorides produced novel esters. The alcohols also reacted with methyl iodide and sodium hydride to provide novel ethers. A one-pot cyclization-esterification of 1 to produce esters containing a tetrahydropyran ring, using iodine as a catalyst, was also investigated.

A comprehensive evaluation of the toxicology of cigarette ingredients: aliphatic and aromatic carboxylic acids.

Science.gov (United States)

Coggins, Christopher R E; Liu, Jianmin; Merski, Jerome A; Werley, Michael S; Oldham, Michael J

2011-06-01

Aromatic and aliphatic carboxylic acids are present in tobacco and tobacco smoke. A battery of tests was used to compare the toxicity of mainstream smoke from experimental cigarettes containing eight aromatic and aliphatic carboxylic acids and the salt of one acid that were added individually at three different levels (lowest and highest target inclusions were 100 and 90,000 ppm, respectively). Mainstream smoke from cigarettes containing each of the test ingredients was evaluated using analytical chemistry and assays to measure in vitro cytotoxicity (neutral red uptake) and Salmonella (five strains) mutagenicity. For four of the compounds (citric, lactic, benzoic acids, and sodium benzoate), 90-day rodent inhalation studies were also performed. Although sporadic statistically significant differences in some experimental cigarette smoke constituents occurred, none resulted in significant changes in mutagenicity or cytotoxicity responses, nor in responses measured in the inhalation studies, except for lactic acid (LA). Inclusion of LA resulted in dose-dependent increase in water and caused a dose-dependent decrease in cytotoxicity. Incorporation of LA into cigarettes resulted in several dose-related reductions in histopathology, which were largely restricted to the nasal passages. Incorporation of LA also ameliorated some of the typical decrease in body weight gain seen in cigarette smoke-exposed rats. Inclusion of these ingredients at exaggerated use levels resulted in sporadic dose-related and treatment effects for some smoke constituents, but no toxicological response was noted in the in vitro and in vivo tests performed.

Synthesis of N-acylurea derivatives from carboxylic acids and N,N ...

Indian Academy of Sciences (India)

acid 1 (scheme 1) to the basic nitrogen of the carbodi- imide 2, followed by addition of the carboxylate to form the O-acyl isourea 3. It is known10 that in low dielec- tric constant solvents such as CH2Cl2, formation of 3 occurs instantaneously and, in the absence of a nucle- ophile or a base, it can be stable for many hours.

Pyrazole carboxamides and carboxylic acids as protein kinase inhibitors in aberrant eukaryotic signal transduction

DEFF Research Database (Denmark)

Persson, Tobias; Yde, Christina W.; Rasmussen, Jakob Ewald

2007-01-01

Densely functionalised pyrazole carboxamides and carboxylic acids were synthesised in an expedient manner through saponification and transamidation, respectively, of ester-functionalised pyrazoles. This synthetic protocol allowed for three diversifying steps in which appendages on the pyrazole...

Ethylene biosynthesis by 1-aminocyclopropane-1-carboxylic acid oxidase: a DFT study.

Science.gov (United States)

Bassan, Arianna; Borowski, Tomasz; Schofield, Christopher J; Siegbahn, Per E M

2006-11-24

The reaction catalyzed by the plant enzyme 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO) was investigated by using hybrid density functional theory. ACCO belongs to the non-heme iron(II) enzyme superfamily and carries out the bicarbonate-dependent two-electron oxidation of its substrate ACC (1-aminocyclopropane-1-carboxylic acid) concomitant with the reduction of dioxygen and oxidation of a reducing agent probably ascorbate. The reaction gives ethylene, CO(2), cyanide and two water molecules. A model including the mononuclear iron complex with ACC in the first coordination sphere was used to study the details of O-O bond cleavage and cyclopropane ring opening. Calculations imply that this unusual and complex reaction is triggered by a hydrogen atom abstraction step generating a radical on the amino nitrogen of ACC. Subsequently, cyclopropane ring opening followed by O-O bond heterolysis leads to a very reactive iron(IV)-oxo intermediate, which decomposes to ethylene and cyanoformate with very low energy barriers. The reaction is assisted by bicarbonate located in the second coordination sphere of the metal.

Design of co-crystals/salts of some Nitrogenous bases and some derivatives of thiophene carboxylic acids through a combination of hydrogen and halogen bonds.

Science.gov (United States)

Jennifer, Samson Jegan; Muthiah, Packianathan Thomas

2014-01-01

The utility of N-heterocyclic bases to obtain molecular complexes with carboxylic acids is well studied. Depending on the solid state interaction between the N-heterocyclic base and a carboxylic acid a variety of neutral or ionic synthons are observed. Meanwhile, pyridines and pyrimidines have been frequently chosen in the area of crystal engineering for their multipurpose functionality. HT (hetero trimers) and LHT (linear heterotetramers) are the well known synthons that are formed in the presence of pyrimidines and carboxylic acids. Fourteen crystals involving various substituted thiophene carboxylic acid derivatives and nitrogenous bases were prepared and characterized by using single crystal X-ray diffraction. The 14 crystals can further be divided into two groups [1a-7a], [8b-14b] based on the nature of the nitrogenous base. Carboxylic acid to pyridine proton transfer has occurred in 3 compounds of each group. In addition to the commonly occurring hydrogen bond based pyridine/carboxylic acid and pyrimidine/carboxylic acid synthons which is the reason for assembly of primary motifs, various other interactions like Cl…Cl, Cl…O, C-H…Cl, C-H…S add additional support in organizing these supermolecules into extended architectures. It is also interesting to note that in all the compounds π-π stacking occurs between the pyrimidine-pyrimidine or pyridine-pyridine or acid-acid moieties rather than acid-pyrimidine/pyridine. In all the compounds (1a-14b) either neutral O-H…Npyridyl/pyrimidine or charge-assisted Npyridinium-H…Ocarboxylate hydrogen bonds are present. The HT (hetero trimers) and LHT (linear heterotetramers) are dominant in the crystal structures of the adducts containing N-heterocyclic bases with two proton acceptors (1a-7a). Similar type supramolecular ladders are observed in 5TPC44BIPY (8b), TPC44BIPY (9b), TPC44TMBP (11b). Among the seven compounds [8b-14b] the extended ligands are linear in all except for the TMBP (10b, 11b, 12b). The

Quantitative determination of carboxylic acids, amino acids, carbohydrates, ethanol and hydroxymethylfurfural in honey by (1)H NMR.

Science.gov (United States)

del Campo, Gloria; Zuriarrain, Juan; Zuriarrain, Andoni; Berregi, Iñaki

2016-04-01

A method using (1)H NMR spectroscopy has been developed to quantify simultaneously thirteen analytes in honeys without previous separation or pre-concentration steps. The method has been successfully applied to determine carboxylic acids (acetic, formic, lactic, malic and succinic acids), amino acids (alanine, phenylalanine, proline and tyrosine), carbohydrates (α- and β-glucose and fructose), ethanol and hydroxymethylfurfural in eucalyptus, heather, lavender, orange blossom, thyme and rosemary honeys. Quantification was performed by using the area of the signal of each analyte in the honey spectra, together with external standards. The regression analysis of the signal area against concentration plots, used for the calibration of each analyte, indicates a good linearity over the concentration ranges found in honeys, with correlation coefficients higher than 0.985 for the thirteen quantified analytes. The recovery studies give values over the 93.7-105.4% range with relative standard deviations lower than 7.4%. Good precision, with relative standard deviations over the range of 0.78-5.21% is obtained. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of carboxylic acid type on microstructure and magnetic properties of polymeric complex sol–gel driven NiFe{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Hessien, M.M. [Materials Science & Engineering Group, Department of Chemistry, Faculty of Science, Taif University (Saudi Arabia); Advanced Materials Dept, Central Metallurgical Research and Development Institute (CMRDI), P.O. Box: 87, Helwan, Cairo (Egypt); Mostafa, Nasser Y., E-mail: nmost69@yahoo.com [Materials Science & Engineering Group, Department of Chemistry, Faculty of Science, Taif University (Saudi Arabia); Department of Chemistry, Faculty of Science, Suez Canal University, Ismailia (Egypt); Abd-Elkader, Omar H. [Department of Zoology, Science College, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Electron Microscope and Thin Films Department, National Research Center (NRC), El-Behooth Street, Dokki, Cairo 12622 (Egypt)

2016-01-15

Citric, oxalic and tartaric acids were used for synthesis of NiFe{sub 2}O{sub 4} using polymeric complex precursor route. The dry precursor gels were calcined at various temperatures (400–1100 °C) for 2 h. All carboxylic acids produce iron-deficient NiFe{sub 2}O{sub 4} with considerable amount of α-Fe{sub 2}O{sub 3} at 400 °C. Increase in the annealing temperature caused reaction of α-Fe{sub 2}O{sub 3} with iron-deficient ferrite phase. The amount of initially formed α-Fe{sub 2}O{sub 3} is directly correlated with stability constant and inversely correlated with the decomposition temperature of Fe(III) carboxylate precursors. In case of tartaric acid precursor, single phase of the ferrite was obtained at 450 °C. However, in case of oxalic acid and citric acid precursors, single phase ferrite was obtained at 550 °C and 700 °C, respectively. The lattice parameters were increased with increasing annealing temperature and with decreasing the amount of α-Fe{sub 2}O{sub 3}. Maximum saturation magnetization (55 emu/g) was achieved using tartaric acid precursor annealed at 1100 °C. - Highlights: • Citric, oxalic and tartaric acids were used for synthesis of NiFe{sub 2}O{sub 4}. • Carboxylic acid type affects the produced powders. • At low temperatures all carboxylic acids produce iron-deficient NiFe{sub 2}O{sub 4} and α-Fe{sub 2}O{sub 3}. • α-Fe{sub 2}O{sub 3} is correlated with the decomposition of Fe(III) carboxylate precursors.

Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

Directory of Open Access Journals (Sweden)

M. Vaïtilingom

2011-08-01

Full Text Available The objective of this work was to compare experimentally the contribution of photochemistry vs. microbial activity to the degradation of carboxylic acids present in cloud water. For this, we selected 17 strains representative of the microflora existing in real clouds and worked on two distinct artificial cloud media that reproduce marine and continental cloud chemical composition. Photodegradation experiments with hydrogen peroxide (H₂O₂ as a source of hydroxyl radicals were performed under the same microcosm conditions using two irradiation systems. Biodegradation and photodegradation rates of acetate, formate, oxalate and succinate were measured on both media at 5 °C and 17 °C and were shown to be on the same order of magnitude (around 10⁻¹⁰–10⁻¹¹ M s⁻¹. The chemical composition (marine or continental origin had little influence on photodegradation and biodegradation rates while the temperature shift from 17 °C to 5 °C decreased biodegradation rates of a factor 2 to 5.

In order to test other photochemical scenarios, theoretical photodegradation rates were calculated considering hydroxyl (OH radical concentration values in cloud water estimated by cloud chemistry modelling studies and available reaction rate constants of carboxylic compounds with both hydroxyl and nitrate radicals. Considering high OH concentration ([OH] = 1 × 10⁻¹² M led to no significant contribution of microbial activity in the destruction of carboxylic acids. On the contrary, for lower OH concentration (at noon, [OH] = 1 × 10⁻¹⁴ M, microorganisms could efficiently compete with photochemistry and in similar contributions than the ones estimated by our experimental approach.

Combining these two approaches (experimental and theoretical, our results led to the following conclusions: oxalate was only photodegraded; the photodegradation of formate was usually more

Syntheses, structures, photoluminescence and photocatalysis of 2D layered lanthanide-carboxylates with 2, 2′-dithiodibenzoic acid

Energy Technology Data Exchange (ETDEWEB)

Ding, Ling; Zhong, Jie-Cen; Qiu, Xing-Tai; Sun, Yan-Qiong, E-mail: sunyq@fzu.edu.cn; Chen, Yi-Ping

2017-02-15

Two series of lanthanide-carboxylates, [Ln(2,2′-dtba)(2,2′-Hdtba)(EtOH)]{sub n} (I:Ln=Eu(1a), Dy(1b)) and [Ln(2,2′-dtba)(2,2′-Hdtba)(4,4′-bpy){sub 0.5}]{sub n} (II:Ln=Eu(2a), Dy(2b), Tb(2c) 2,2′-H{sub 2}dtba=2,2′-dithiodibenzoic acid, 4,4′-bpy=4,4′-bipyridine) have been synthesized under hydrothermal conditions. Interestingly, the H{sub 2}dtba organic ligand was generated by in situ S–S reaction of 2-mercaptobenzoic acid. Compounds I and II possess different 2D layered structures based on similar 1D [Ln(2,2′-dtba)]{sup +} chains. Photoluminescence studies reveal that compounds I and II exhibit strong lanthanide characteristic emission bands. Remarkably, Compounds 1b and 2a both exhibit good photocatalytic activity for degradation of Rhodamine-B (Rh-B) under the simulated sunlight irradiation. - Graphical abstract: Two series of lanthanide-carboxylates have been in situ synthesized under hydrothermal conditions. The lanthanide-carboxylates exhibit strong lanthanide characteristic emission bands and good photocatalytic activity for degradation of Rhodamine-B. - Highlights: • 2D layered lanthanide-carboxylates with 2,2′-dithiodibenzoic acid. • In situ S–S reaction of 2-mercaptobenzoic acid under hydrothermal condition. • The Emission spectra of I and II exhibit the characteristic transition of lanthanide ions. • Compounds 1b and 2a exhibit good photocatalytic activity for degradation of Rhodamine-B.

Approaches to α-amino acids via rearrangement to electron-deficient nitrogen: Beckmann and Hofmann rearrangements of appropriate carboxyl-protected substrates

Directory of Open Access Journals (Sweden)

Sosale Chandrasekhar

2012-08-01

Full Text Available The titled approaches were effected with various 2-substituted benzoylacetic acid oximes 3 (Beckmann and 2-substituted malonamic acids 9 (Hofmann, their carboxyl groups being masked as a 2,4,10-trioxaadamantane unit (an orthoacetate. The oxime mesylates have been rearranged with basic Al2O3 in refluxing CHCl3, and the malonamic acids with phenyliodoso acetate and KOH/MeOH. Both routes are characterized by excellent overall yields. Structure confirmation of final products was conducted with X-ray diffraction in selected cases. The final N-benzoyl and N-(methoxycarbonyl products are α-amino acids with both carboxyl and amino protection; hence, they are of great interest in peptide synthesis.

Phosphazene-promoted metal-free ring-opening polymerization of ethylene oxide initiated by carboxylic acid

KAUST Repository

Zhao, Junpeng; Pahovnik, David; Gnanou, Yves; Hadjichristidis, Nikolaos

2014-01-01

The effectiveness of carboxylic acid as initiator for the anionic ring-opening polymerization of ethylene oxide was investigated with a strong phosphazene base (t-BuP4) used as promoter. Kinetic study showed an induction period, i.e., transformation

The protonation state of small carboxylic acids at the water surface from photoelectron spectroscopy

Czech Academy of Sciences Publication Activity Database

Ottosson, N.; Wernersson, Erik; Söderström, J.; Pokapanich, W.; Kaufmann, S.; Svensson, S.; Persson, I.; Öhrwall, G.; Björneholm, O.

2011-01-01

Roč. 13, č. 26 (2011), s. 12261-12267 ISSN 1463-9076 Institutional research plan: CEZ:AV0Z40550506 Keywords : water surface * carboxylic acids * photoelectron spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.573, year: 2011

New derivatives of 3,4-dihydroisoquinoline-3-carboxylic acid with free-radical scavenging, D-amino acid oxidase, acetylcholinesterase and butyrylcholinesterase inhibitory activity.

Science.gov (United States)

Solecka, Jolanta; Guśpiel, Adam; Postek, Magdalena; Ziemska, Joanna; Kawęcki, Robert; Lęczycka, Katarzyna; Osior, Agnieszka; Pietrzak, Bartłomiej; Pypowski, Krzysztof; Wyrzykowska, Agata

2014-09-30

A series of 3,4-dihydroisoquinoline-3-carboxylic acid derivatives were synthesised and tested for their free-radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS·+), superoxide anion radical (O2·-) and nitric oxide radical (·NO) assays. We also studied d-amino acid oxidase (DAAO), acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activity. Almost each of newly synthesised compounds exhibited radical scavenging capabilities. Moreover, several compounds showed moderate inhibitory activities against DAAO, AChE and BuChE. Compounds with significant free-radical scavenging activity may be potential candidates for therapeutics used in oxidative-stress-related diseases.

Synthesis and Transformations of di-endo-3-Aminobicyclo-[2.2.2]oct-5-ene-2-carboxylic Acid Derivatives

Directory of Open Access Journals (Sweden)

Márta Palkó

2011-09-01

Full Text Available all-endo-3-amino-5-hydroxybicyclo[2.2.2]octane-2-carboxylic acid (13 and all-endo-5-amino-6-(hydroxymethylbicyclo[2.2.2]octan-2-ol (10 were prepared via dihydro-1,3-oxazine or g-lactone intermediates by the stereoselective functionalization of an N-protected derivative of endo-3-aminobicyclo[2.2.2]oct-5-ene-2-carboxylic acid (2. Ring closure of b-amino ester 4 resulted in tricyclic pyrimidinones 15 and 16. The structures, stereochemistry and relative configurations of the synthesized compounds were determined by IR and NMR.

Polyoxyethylene alkyl ether carboxylic acids: An overview of a neglected class of surfactants with multiresponsive properties.

Science.gov (United States)

Chiappisi, Leonardo

2017-12-01

In this work, an overview on aqueous solutions of polyoxyethylene alkyl ether carboxylic acids is given. Unique properties arise from the combination of the nonionic, temperature-responsive polyoxyethylene block with the weakly ionic, pH-responsive carboxylic acid termination in a single surfactant headgroup. Accordingly, this class of surfactant finds broad application across very different sectors. Despite their large use on an industrial and a technical scale, the literature lacks a systematic and detailed characterization of their physico-chemical properties which is provided herein. In addition, a comprehensive overview is given of their self-assembly and interfacial behavior, of their use as colloidal building blocks and for large-scale applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of scandium ionic associates with salicylic- or 2-phenylquinoline-4-carboxylic acid and rhodamine C

Energy Technology Data Exchange (ETDEWEB)

Kononenko, L.I.; Bel' tyukova, S V; Drobyazko, V N; Poluehktov, N S [AN Ukrainskoj SSR, Kiev. Inst. Obshchej i Neorganicheskoj Khimii; AN Ukrainskoj SSR, Odessa. Inst. Obshchej i Neorganicheskoj Khimii)

1975-09-01

With salicylic or 2-phenylquinoline-4-carboxylic acid and rhodamine C scandium forms ion associations whose benzene solutions are capable of luminescence. Optimum conditions for the formation of complexes and the composition of the complex with the ratio of Sc:acid:rhodamine C = 1:2:1 are established. A possibility of luminescence determination of scandium in the presence of rare earths is shown.

Novel Isoniazid cocrystals with aromatic carboxylic acids: Crystal engineering, spectroscopy and thermochemical investigations

Science.gov (United States)

Diniz, Luan F.; Souza, Matheus S.; Carvalho, Paulo S.; da Silva, Cecilia C. P.; D'Vries, Richard F.; Ellena, Javier

2018-02-01

Four novel cocrystals of the anti-tuberculosis drug Isoniazid (INH), including two polymorphs, with the aromatic carboxylic acids p-nitrobenzoic (PNBA), p-cyanobenzoic (PCNBA) and p-aminobenzoic (PABA) were rationally designed and synthesized by solvent evaporation. Aiming to explore the possible supramolecular synthons of this API, these cocrystals were fully characterized by X-ray diffraction (SCXRD, PXRD), spectroscopic (FT-IR) and thermal (TGA, DSC, HSM) techniques. The cocrystal formation was found to be mainly driven by the synthons formed by the pyridine and hydrazide moieties. In both INH-PABA polymorphs, the COOH acid groups are H-bonded to pyridine and hydrazide groups giving rise to the acid⋯pyridine and acid⋯hydrazide heterosynthons. In INH-PNBA and INH-PCNBA cocrystals these acid groups are only related to the pyridine moiety. In addition to the structural study, supramolecular and Hirshfeld surface analysis were also performed based on the structural data. The cocrystals were identified from the FT-IR spectra and their thermal behaviors were studied by a combination of DSC, TGA and HSM techniques.

Recovery of carboxylic acids produced during dark fermentation of food waste by adsorption on Amberlite IRA-67 and activated carbon.

Science.gov (United States)

Yousuf, Ahasa; Bonk, Fabian; Bastidas-Oyanedel, Juan-Rodrigo; Schmidt, Jens Ejbye

2016-10-01

Amberlite IRA-67 and activated carbon were tested as promising candidates for carboxylic acid recovery by adsorption. Dark fermentation was performed without pH control and without addition of external inoculum at 37°C in batch mode. Lactic, acetic and butyric acids, were obtained, after 7days of fermentation. The maximum acid removal, 74%, from the Amberlite IRA-67 and 63% from activated carbon was obtained from clarified fermentation broth using 200gadsorbent/Lbroth at pH 3.3. The pH has significant effect and pH below the carboxylic acids pKa showed to be beneficial for both the adsorbents. The un-controlled pH fermentation creates acidic environment, aiding in adsorption by eliminating use of chemicals for efficient removal. This study proposes simple and easy valorization of waste to valuable chemicals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of carboxylic acids as compatibilizer agent on mechanical properties of thermoplastic starch and polypropylene blends.

Science.gov (United States)

Martins, Andréa Bercini; Santana, Ruth Marlene Campomanes

2016-01-01

In this work, polypropylene/thermoplastic starch (PP/TPS) blends were prepared as an alternative material to use in disposable packaging, reducing the negative polymeric environmental impact. Unfortunately, this material displays morphological characteristics typical of immiscible polymer blends and a compatibilizer agent is needed. Three different carboxyl acids: myristic (C14), palmitic (C16) and stearic acids (C18) were used as natural compatibilizer agent (NCA). The effects of NCA on the mechanical, physical, thermal and morphological properties of PP/TPS blends were investigated and compared against PP/TPS with and without PP-grafted maleic anhydride (PPgMA). When compared to PP/TPS, blends with C18, PPgMA and C14 presented an improvement of 25, 22 and 17% in tensile strength at break and of 180, 194 and 259% in elongation at break, respectively. The highest increase, 54%, in the impact strength was achieved with C14 incorporation. Improvements could be seen, through scanning electron microscopy (SEM) images, in the compatibility between the immiscible components by acids incorporation. These results showed that carboxylic acids, specifically C14, could be used as compatibilizer agent and could substitute PPgMA. Copyright © 2015 Elsevier Ltd. All rights reserved.

Difference between Extra- and Intracellular T1 Values of Carboxylic Acids Affects the Quantitative Analysis of Cellular Kinetics by Hyperpolarized NMR

DEFF Research Database (Denmark)

Karlsson, Magnus; Jensen, Pernille Rose; Ardenkjær-Larsen, Jan Henrik

2016-01-01

on the quantification of intracellular metabolicactivity. It is expected that the significantly shorter T1valueof the carboxylic moieties inside cells is a result of macro-molecular crowding. An artificial cytosol has been preparedand applied to predict the T1of other carboxylic acids. Wedemonstrate the value......Incomplete knowledge of the longitudinal relaxationtime constant (T1) leads to incorrect assumptions in quantita-tive kinetic models of cellular systems, studied by hyper-polarized real-time NMR. Using an assay that measures theintracellular signal of small carboxylic acids in living cells...

Rapid Screening of Carboxylic Acids from Waste and Surface Waters by ESI-MS/MS Using Barium Ion Chemistry and On-Line Membrane Sampling

Science.gov (United States)

Duncan, Kyle D.; Volmer, Dietrich A.; Gill, Chris G.; Krogh, Erik T.

2016-03-01

Negative ion tandem mass spectrometric analysis of aliphatic carboxylic acids often yields only non-diagnostic ([M - H]-) ions with limited selective fragmentation. However, carboxylates cationized with Ba2+ have demonstrated efficient dissociation in positive ion mode, providing structurally diagnostic product ions. We report the application of barium adducts followed by collision induced dissociation (CID), to improve selectivity for rapid screening of carboxylic acids in complex aqueous samples. The quantitative MS/MS method presented utilizes common product ions of [M - H + Ba]+ precursor ions. The mechanism of product ion formation is investigated using isotopically labeled standards and a series of structurally related carboxylic acids. The results suggest that hydrogen atoms in the β and γ positions yield common product ions ([BaH]+ and [BaOH]+). Furthermore, the diagnostic product ion at m/z 196 serves as a qualifying ion for carboxylate species. This methodology has been successfully used in conjunction with condensed phase membrane introduction mass spectrometry (CP-MIMS), with barium acetate added directly to the methanol acceptor phase. The combination enables rapid screening of carboxylic acids directly from acidified water samples (wastewater effluent, spiked natural waters) using a capillary hollow fiber PDMS membrane immersion probe. We have applied this technique for the direct analysis of complex naphthenic acid mixtures spiked into natural surface waters using CP-MIMS. Selectivity at the ionization and tandem mass spectrometry level eliminate isobaric interferences from hydroxylated species present within the samples, which have been observed in negative electrospray ionization.

Rapid Screening of Carboxylic Acids from Waste and Surface Waters by ESI-MS/MS Using Barium Ion Chemistry and On-Line Membrane Sampling.

Science.gov (United States)

Duncan, Kyle D; Volmer, Dietrich A; Gill, Chris G; Krogh, Erik T

2016-03-01

Negative ion tandem mass spectrometric analysis of aliphatic carboxylic acids often yields only non-diagnostic ([M - H](-)) ions with limited selective fragmentation. However, carboxylates cationized with Ba(2+) have demonstrated efficient dissociation in positive ion mode, providing structurally diagnostic product ions. We report the application of barium adducts followed by collision induced dissociation (CID), to improve selectivity for rapid screening of carboxylic acids in complex aqueous samples. The quantitative MS/MS method presented utilizes common product ions of [M - H + Ba](+) precursor ions. The mechanism of product ion formation is investigated using isotopically labeled standards and a series of structurally related carboxylic acids. The results suggest that hydrogen atoms in the β and γ positions yield common product ions ([BaH](+) and [BaOH](+)). Furthermore, the diagnostic product ion at m/z 196 serves as a qualifying ion for carboxylate species. This methodology has been successfully used in conjunction with condensed phase membrane introduction mass spectrometry (CP-MIMS), with barium acetate added directly to the methanol acceptor phase. The combination enables rapid screening of carboxylic acids directly from acidified water samples (wastewater effluent, spiked natural waters) using a capillary hollow fiber PDMS membrane immersion probe. We have applied this technique for the direct analysis of complex naphthenic acid mixtures spiked into natural surface waters using CP-MIMS. Selectivity at the ionization and tandem mass spectrometry level eliminate isobaric interferences from hydroxylated species present within the samples, which have been observed in negative electrospray ionization.

In vitro assessment of potential intestinal absorption of some phenolic families and carboxylic acids from commercial instant coffee samples.

Science.gov (United States)

López-Froilán, R; Ramírez-Moreno, E; Podio, N S; Pérez-Rodríguez, M L; Cámara, M; Baroni, M V; Wunderlin, D A; Sánchez-Mata, M C

2016-06-15

Coffee is one of the most consumed beverages in the world, being a source of bioactive compounds as well as flavors. Hydroxycinnamic acids, flavonols, and carboxylic acids have been studied in the samples of instant coffee commercialized in Spain. The studies about contents of food components should be complemented with either in vitro or in vivo bioaccessibility studies to know the amount of food components effectively available for functions in the human body. In this sense, a widely used in vitro model has been applied to assess the potential intestinal absorption of phenolic compounds and organic acids. The contents of hydroxycinnamic acids and flavonols were higher in instant regular coffee samples than in the decaffeinated ones. Bioaccessible phenolic compounds in most analyzed samples account for 20-25% of hydroxycinnamic acids and 17-26% of flavonols. This could mean that a great part of them can remain in the gut, acting as potential in situ antioxidants. Quinic, acetic, pyroglutamic, citric and fumaric acids were identified in commercial instant coffee samples. Succinic acid was found in the coffee blend containing chicory. All carboxylic acids showed a very high bioaccessibility. Particularly, acetic acid and quinic acid were found in higher contents in the samples treated with the in vitro simulation of gastrointestinal processes, compared to the original ones, which can be explained by their cleavage from chlorogenic acid during digestion. This is considered as a positive effect, since quinic acid is considered as an antioxidant inducer.

Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

Science.gov (United States)

Giresse Tetsassi Feugmo, Conrard; Champagne, Benoît; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J.; Liégeois, Vincent

2012-03-01

In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement.

Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

International Nuclear Information System (INIS)

Tetsassi Feugmo, Conrard Giresse; Champagne, Benoît; Liégeois, Vincent; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J

2012-01-01

In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement. (paper)

l-2-Nitrimino-1,3-diazepane-4-carboxylic acid

Directory of Open Access Journals (Sweden)

Harutyun A. Karapetyan

2008-05-01

Full Text Available The cyclic form of l-nitroarginine, C6H10N4O4, crystallizes with two independent molecules in the asymmetric unit. According to the geometrical parameters, similar in both molecules, the structure corresponds to that of l-2-nitrimino-1,3-diazepane-4-carboxylic acid; there are, however, conformational differences between the independent molecules, one of them being close to a twisted chair while the other might be described as a rather flattened boat. All six active H atoms in the two molecules are involved in hydrogen bonds, two of which are intramolecular and four intermolecular, forming an infinite chain of molecules along the b axis.

Redshift or adduct stabilization -- a computational study of hydrogen bonding in adducts of protonated carboxylic acids

DEFF Research Database (Denmark)

Olesen, Solveig Gaarn; Hammerum, Steen

2009-01-01

It is generally expected that the hydrogen bond strength in a D-H-A adduct is predicted by the difference between the proton affinities of D and A, measured by the adduct stabilization, and demonstrated by the IR redshift of the D-H bond stretching vibrational frequency. These criteria do...... not always yield consistent predictions, as illustrated by the hydrogen bonds formed by the E and Z OH groups of protonated carboxylic acids. The delta-PA and the stabilization of a series of hydrogen bonded adducts indicate that the E OH group forms the stronger hydrogen bonds, whereas the bond length...... carboxylic acids are different. The OH bond length and IR redshift afford the better measure of hydrogen bond strength....

Determining aromatic and aliphatic carboxylic acids in biomass-derived oil samples using 2,4-dinitrophenylhydrazine and liquid chromatography-electrospray injection-mass spectrometry/mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Lewis, Samuel A.; Connatser, Raynella M.; Olarte, Mariefel V.; Keiser, James R.

2018-01-01

Converting biomass to a useful fuel commonly incorporates the pyrolysis of the biomass feed stock. The base liquid fraction usually contains high concentrations of ketones, aldehydes and carboxylic acids, of which each can cause detrimental issues related to the storage and upgrading process. Knowing the carbonyl species and the concentration of each will provide value information to the pyrolysis researchers, specifically as that community branches into more targeted end-products such as jet fuel or biogenic-derived oxygenate-containing fuel products. The analysis of aldehydes, ketones and small alkyl carboxylic acids using 2,4-dinitrophenylhydrazine (DNPH) derivation method has been well documented and the method is commonly used the analytical community. By using liquid chromatograph coupled to tandem mass spectrometry, biomass sample analysis can be complete with identification of most carbonyl species. The issue of identifying isobaric ketone and aldehyde compounds can be resolved by utilizing differences in retention time or characteristic fragment ions of ketones and aldehydes. One issue which could not resolved using published methods was identifying aromatic or large non-aromatic carboxylic acids from their corresponding hydroxyl aldehyde or ketone analogs. By modifying the current method for determining carbonyls in biomass samples, carboxylic and hydroxyl-carbonyl can be determined. A careful adjustment of the pH during the extraction procedure and extended heating time of the DNPH solution allowed for the successful derivation of aromatic carboxylic acids. Like other dinitrophenylhydrazones, carboxylic acid derivatives also produce a unique secondary ion pattern, which was useful to distinguish these species from the non-acid analogs.

Sulfonated reduced graphene oxide as a highly efficient catalyst for direct amidation of carboxylic acids with amines using ultrasonic irradiation.

Science.gov (United States)

Mirza-Aghayan, Maryam; Tavana, Mahdieh Molaee; Boukherroub, Rabah

2016-03-01

Sulfonated reduced graphene oxide nanosheets (rGO-SO3H) were prepared by grafting sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide (rGO) under sonochemical conditions. rGO-SO3H catalyst was characterized by Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). rGO-SO3H catalyst was successfully applied as a reusable solid acid catalyst for the direct amidation of carboxylic acids with amines into the corresponding amides under ultrasonic irradiation. The direct sonochemical amidation of carboxylic acid takes place under mild conditions affording in good to high yields (56-95%) the corresponding amides in short reaction times. Copyright © 2015 Elsevier B.V. All rights reserved.

Degradation of chitosan hydrogel dispersed in dilute carboxylic acids by solution plasma and evaluation of anticancer activity of degraded products

Science.gov (United States)

Chokradjaroen, Chayanaphat; Rujiravanit, Ratana; Theeramunkong, Sewan; Saito, Nagahiro

2018-01-01

Chitosan is a polysaccharide that has been extensively studied in the field of biomedicine, especially its water-soluble degraded products called chitooligosaccharides (COS). In this study, COS were produced by the degradation of chitosan hydrogel dispersed in a dilute solution (i.e., 1.55 mM) of various kinds of carboxylic acids using a non-thermal plasma technology called solution plasma (SP). The degradation rates of chitosan were influenced by the type of carboxylic acids, depending on the interaction between chitosan and each carboxylic acid. After SP treatment, the water-soluble degraded products containing COS could be easily separated from the water-insoluble residue of chitosan hydrogel by centrifugation. The production yields of the COS were mostly higher than 55%. Furthermore, the obtained COS products were evaluated for their inhibitory effect as well as their selectivity against human lung cancer cells (H460) and human lung normal cells (MRC-5).

Determination of perfluoroalkyl carboxylic, sulfonic, and phosphonic acids in food.

Science.gov (United States)

Ullah, Shahid; Alsberg, Tomas; Vestergren, Robin; Berger, Urs

2012-11-01

A sensitive and accurate method was developed and validated for simultaneous analysis of perfluoroalkyl carboxylic acids, sulfonic acids, and phosphonic acids (PFPAs) at low picograms per gram concentrations in a variety of food matrices. The method employed extraction with acetonitrile/water and cleanup on a mixed-mode co-polymeric sorbent (C8 + quaternary amine) using solid-phase extraction. High-performance liquid chromatographic separation was achieved on a C18 column using a mobile phase gradient containing 5 mM 1-methyl piperidine for optimal chromatographic resolution of PFPAs. A quadrupole time-of-flight high-resolution mass spectrometer operating in negative ion mode was used as detector. Method detection limits were in the range of 0.002 to 0.02 ng g(-1) for all analytes. Sample preparation (extraction and cleanup) recoveries at a spiking level of 0.1 ng g(-1) to a baby food composite were in the range of 59 to 98 %. A strong matrix effect was observed in the analysis of PFPAs in food extracts, which was tentatively assigned to sorption of PFPAs to the injection vial in the solvent-based calibration standard. The method was successfully applied to a range of different food matrices including duplicate diet samples, vegetables, meat, and fish samples.

Non-Acidic Free Fatty Acid Receptor 4 Agonists with Antidiabetic Activity

DEFF Research Database (Denmark)

Goncalves de Azavedo, Carlos M. B. P.; Watterson, Kenneth R; Wargent, Ed T

2016-01-01

The free fatty acid receptor 4 (FFA4 or GPR120) has appeared as an interesting potential target for the treatment of metabolic disorders. At present, most FFA4 ligands are carboxylic acids that are assumed to mimic the endogenous long-chain fatty acid agonists. Here, we report preliminary structure......-activity relationship studies of a previously disclosed non-acidic sulfonamide FFA4 agonist. Mutagenesis studies indicate that the compounds are orthosteric agonists despite the absence of a carboxylate function. The preferred compounds showed full agonist activity on FFA4 and complete selectivity over FFA1, although...... a significant fraction of these non-carboxylic acids also showed partial antagonistic activity on FFA1. Studies in normal and diet-induced obese (DIO) mice with the preferred compound 34 showed improved glucose tolerance after oral dosing in an oral glucose tolerance test. Chronic dosing of 34 in DIO mice...

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.

6-Substituted 3,4-dihydro-naphthalene-2-carboxylic acids: synthesis and structure-activity studies in a novel class of human 5alpha reductase inhibitors.

Science.gov (United States)

Baston, Eckhard; Salem, Ola I A; Hartmann, Rolf W

2002-10-01

Novel 3,4-dihydro-naphthalene-2-carboxylic acids were synthesized and evaluated for 5alpha reductase inhibitory activity. This enzyme exists in two isoforms and is a pharmacological target for the treatment of benign prostatic hyperplasia, male pattern baldness and acne. In the present study non-steroidal compounds capable of mimicking the transition state of the steroidal substrates were prepared. The synthetic strategy for the preparation of compounds 1-6 consisted of triflation followed by subsequent Heck-type carboxylation or methoxy carbonylation for 6-phenyl-3,4-dihydronaphthalen-2(1H)-one 1c. A Negishi-type coupling reaction between 6-(trifluoro-methanesulfonyloxy)-3,4-dihydro-naphthalene-2-carboxylic acid methyl ester 7b and various aryl bromides led, after further transformations, to 6-substituted 3,4-dihydro-naphthalene-2-carboxylic acids 7-15. In a similar way the corresponding naphthalene-2-carboxylic acids 16 and 17 were obtained. The DU 145 cell line and prostate homogenates served as enzyme sources for the human type 1 and type 2 isozymes, whereas ventral prostate was employed to evaluate rat isozyme inhibitory potency. The most active inhibitors identified in this study were 6-[4-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (3) (IC50 = 0.09 microM, rat type 1), 6-[3-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (13) (IC50 = 0.75 microM, human type 2; IC50 = 0.81 microM, human type 1) and 6-[4-(N,N-diisopropylamino-carbonyl)phenyl]naphthalene-2-carboxylic acid (16) (IC50 = 0.2 microM, human type 2). The latter compound was shown to deactivate the enzyme in an uncompetitive manner (Ki = 90 nM; Km, Testosterone = 0.8-1.0 microM) similar to the steroidal inhibitor Epristeride. Select inhibitors (13 and 16) were tested in vivo using testosterone propionate-treated, juvenile, orchiectomized SD-rats. None of the compounds was active at a dose of 25 mg/kg. This result might in part be

Developmental Toxicity of (4S-2- (4-hydroxy-3-methoxyphenyl thiazolidine-4-carboxylic acid in Zebrafish ( Danio rerio

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Cansu Akbulut

2017-08-01

Full Text Available ABSTRACT (4S-2-(4-hydroxy-3-methoxyphenylthiazolidine-4-carboxylic acid is new synthesized substance obtained from cysteine and valine. Thiazolidine derivates have important biological responses so scientists work intensively on these compounds in recent years. It is obvious that thiazolidine contained compounds will be used in future in the pharmaceutical industry to treat important diseases. Median lethal concentrations (LC50 for 48 h and 96 h were found as 1.106±0.052 mM and 0.804mM ± 0.102 respectively. According to LC50, exposure doses were determined as control, 0.4 mM, 0.2 mM and 0.1 mM (4S-2-(4-hydroxy-3-methoxyphenylthiazolidine-4-carboxylic acid. Developmental toxicity and apoptotic features on zebrafish development were evaluated in this study. The results of this study indicate that (4S-2-(4-hydroxy-3-methoxyphenylthiazolidine-4-carboxylic acid exposure cause developmental defects like pericardial edema, bent spine, tail malformation, blood accumulation, yolk sac edema but on the other hand concentration-dependent decrease in apoptotic rate. Likewise, concentration-dependent decrease in hatching and increase in mortality of embryos were also detected.

Bienzymatic Acetylcholinesterase and Choline Oxidase Immobilized Biosensor Based on a Phenyl Carboxylic Acid-Grafted Multiwalled Carbon Nanotube

Directory of Open Access Journals (Sweden)

So-Ra Lee

2014-01-01

Full Text Available Bienzymatic acetylcholinesterase (AChE and choline oxidase (ChOx immobilized biosensor based on a phenyl carboxylic acid-grafted multiwalled carbon nanotube (MWNT modified glass carbon electrode (GCE and carbon-screen printed electrode (SPE was fabricated for acetylcholine detection in human blood samples. Phenyl carboxylic acid-modified MWNT supports were prepared by electrochemical polymerization of 4-carboxyphenyl diazonium salts, which were synthesized by an amine group and sodium nitrite, on the surface of the MWNT-modified GCE and SPE in 0.1 M PBS. The successful fabrication of the AChE-ChOx-immobilized biosensor was confirmed via scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, electrochemical impedance spectroscopy (EIS, and cyclic voltammetry (CV. The sensing range of the biosensor based on a GCE and SPE was 1.0~10 μM and 10~100 μM, respectively. The interfering effect of 0.1 M L-ascorbic acid, 0.1 M L-cysteine, and 0.1 M uric acid to 0.1 M acetylcholine was 3.00%, 9.00%, and 3.00%, respectively. Acetylcholine in a human blood sample was detected by the AChE-ChOx-immobilized biosensor.

Copper Complexes of Nicotinic-Aromatic Carboxylic Acids as Superoxide Dismutase Mimetics

Directory of Open Access Journals (Sweden)

Virapong Prachayasittikul

2008-12-01

Full Text Available Nicotinic acid (also known as vitamin B3 is a dietary element essential for physiological and antihyperlipidemic functions. This study reports the synthesis of novel mixed ligand complexes of copper with nicotinic and other select carboxylic acids (phthalic, salicylic and anthranilic acids. The tested copper complexes exhibited superoxide dismutase (SOD mimetic activity and antimicrobial activity against Bacillus subtilis ATCC 6633, with a minimum inhibition concentration of 256 μg/mL. Copper complex of nicotinic-phthalic acids (CuNA/Ph was the most potent with a SOD mimetic activity of IC50 34.42 μM. The SOD activities were observed to correlate well with the theoretical parameters as calculated using density functional theory (DFT at the B3LYP/LANL2DZ level of theory. Interestingly, the SOD activity of the copper complex CuNA/Ph was positively correlated with the electron affinity (EA value. The two quantum chemical parameters, highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO, were shown to be appropriate for understanding the mechanism of the metal complexes as their calculated energies show good correlation with the SOD activity. Moreover, copper complex with the highest SOD activity were shown to possess the lowest HOMO energy. These findings demonstrate a great potential for the development of value-added metallovitamin-based therapeutics.

Sulfur-containing constituents and one 1H-pyrrole-2-carboxylic acid derivative from pineapple [Ananas comosus (L.) Merr.] fruit.

Science.gov (United States)

Zheng, Zong-Ping; Ma, Jinyu; Cheng, Ka-Wing; Chao, Jianfei; Zhu, Qin; Chang, Raymond Chuen-Chung; Zhao, Ming; Lin, Zhi-Xiu; Wang, Mingfu

2010-12-01

Two sulfur-containing compounds, (S)-2-amino-5-((R)-1-carboxy-2-((E)-3-(4-hydroxy-3-methoxyphenyl)allylthio)ethyl-amino)-5-oxopentanoic acid (1) and (S)-2-amino-5-((R)-1-(carboxymethylamino)-3-((E)-3-(4-hydroxyphenyl)allylthio)-1-oxopropan-2-ylamino)-5-oxopentanoic acid (2), and one 1H-pyrrole-2-carboxylic acid derivative, 6-(3-(1H-pyrrole-2-carbonyloxy)-2-hydroxypropoxy)-3,4,5-trihydroxy-tetrahydro-2H-pyran-2-carboxylic acid (3), together with eighteen known phenolic compounds, were isolated from the fruits of pineapple. Their structures were elucidated by a combination of spectroscopic analyses. Some of these compounds showed inhibitory activities against tyrosinase. The half maximal inhibitory concentration values of compounds 1, 4, 5, 6, 7 are lower than 1 mM. These compounds may contribute to the well-known anti-browning effect of pineapple juice and be potential skin whitening agents in cosmetic applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

Mechanism of catalytic action of oxide systems in reactions of aldehyde oxidation to carboxylic acids

International Nuclear Information System (INIS)

Andrushkevich, T.V.

1997-01-01

Mechanism of selective action of oxide catalysts (on the base of V 2 O 4 , MoO 3 ) of aldehyde oxidation to acids is considered, reaction acrolein oxidation to acrylic acid is taken as an example. Multistage mechanism of the process is established; it involves consequent transformation of coordination-bonded aldehyde into carbonyl-bonded aldehyde and symmetric carboxylate. Principles of active surface construction are formulated, they take into account the activity of stabilization center of concrete intermediate compound and bond energy of oxygen with surface. (author)

Determination of the conformation of 2-hydroxy- and 2-aminobenzoic acid dimers using 13C NMR and density functional theory/natural bond order analysis: the central importance of the carboxylic acid carbon.

Science.gov (United States)

Burnette, Ronald R; Weinhold, Frank

2006-07-20

The 13C chemical shift for the carboxylic acid carbon provides a powerful diagnostic probe to determine the preferred isomeric dimer structures of benzoic acid derivatives undergoing intra- and intermolecular H-bonding in the gas, solution and crystalline phases. We have employed hybrid density functional calculations and natural bond orbital analysis to elucidate the electronic origins of the observed 13C shieldings and their relationship to isomeric stability. We find that delocalizing interactions from the carbonyl oxygen lone pairs (nO) into vicinal carbon-oxygen and carbon-carbon antibonds (sigmaCO*,sigmaCC*) make critical contributions to the 13C shieldings, and these nO --> sigmaCO*, nO --> sigmaCC* interactions are in turn sensitive to the intramolecular interactions that dictate dimer structure and stability. The carboxyl carbon atom can thus serve as a useful detector of subtle structural and conformational features in this pharmacologically important class of carboxylic acid interactions.

Structure of eight molecular salts assembled from noncovalent bonding between carboxylic acids, imidazole, and benzimidazole

Science.gov (United States)

Jin, Shouwen; Zhang, Huan; Liu, Hui; Wen, Xianhong; Li, Minghui; Wang, Daqi

2015-09-01

Eight organic salts of imidazole/benzimidazole have been prepared with carboxylic acids as 2-methyl-2-phenoxypropanoic acid, α-ketoglutaric acid, 5-nitrosalicylic acid, isophthalic acid, 4-nitro-phthalic acid, and 3,5-dinitrosalicylic acid. The eight crystalline forms reported are proton-transfer compounds of which the crystals and compounds were characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. These structures adopted hetero supramolecular synthons, with the most common R22(7) motif observed at salts 2, 3, 5, 6 and 8. Analysis of the crystal packing of 1-8 suggests that there are extensive strong Nsbnd H⋯O, and Osbnd H⋯O hydrogen bonds (charge assisted or neutral) between acid and imidazolyl components in all of the salts. Except the classical hydrogen bonding interactions, the secondary propagating interactions also play important roles in structure extension. This variety, coupled with the varying geometries and number of acidic groups of the acids utilized, has led to the creation of eight supramolecular arrays with 1D-3D structure. The role of weak and strong noncovalent interactions in the crystal packing is analyzed. The results presented herein indicate that the strength and directionality of the Nsbnd H⋯O, and Osbnd H⋯O hydrogen bonds between acids and imidazole/benzimidazole are sufficient to bring about the formation of organic salts.

Luminescent hybrid lanthanide sulfates and lanthanide sulfonate-carboxylates with 1,10-phenanthroline involving in-situ oxidation of 2-mercaptonbenzoic acid

International Nuclear Information System (INIS)

Zhong, Jie-Cen; Wan, Fang; Sun, Yan-Qiong; Chen, Yi-Ping

2015-01-01

A series of lanthanide sulfates and lanthanide sulfonate-carboxylates, [Ln 2 (phen) 2 (SO 4 ) 3 (H 2 O) 2 ] n (I:Ln=Nd(1a), Sm(1b), Eu(1c), phen=1,10-phenanthroline) and [Ln(phen)(2-SBA)(BZA)] n (II: Ln=Sm(2a), Eu(2b), Dy(2c), 2-SBA=2-sulfobenzoate, BZA=benzoate) have been hydrothermally synthesized from lanthanide oxide, 2-mercaptonbenzoic acid with phen as auxiliary ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, TG analyses and luminescence spectroscopy. Interestingly, SO 4 2− anions in I came from the in situ deep oxidation of thiol groups of 2-mercaptonbenzoic acid while 2-sulfobenzoate and benzoate ligands in II from the middle oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. Compounds I are organic–inorganic hybrid lanthanide sulfates, which have rare one-dimensional column-like structures. Complexes II are binuclear lanthanide sulfonate-carboxylates with 2-sulfobenzoate and benzoate as bridges and 1,10-phenanthroline as terminal. Photoluminescence studies reveal that complexes I and II exhibit strong lanthanide characteristic emission bands in the solid state at room temperature. - Graphical abstract: Lanthanide sulfates and lanthanide sulfonate-carboxylates have been hydrothermally synthesized. Interestingly, sulfate anions, 2-sulfobenzoate and benzoate ligands came from the in situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. - Highlights: • In situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. • The organic–inorganic hybrid lanthanide sulfates with one-dimensional column-like structure. • The dinuclear lanthanide sulfonate-carboxylates. • The emission spectra exhibit the characteristic transition of 5 D 0 → 7 F J (J=0–4) of the Eu(III)

A Convenient One-Pot Method for the Synthesis of N-Methoxy-N-methyl Amides from Carboxylic Acids

International Nuclear Information System (INIS)

Kim, Joong Gon; Jang, Doo Ok

2010-01-01

We have developed a mild and convenient method for one-pot synthesis of Weinreb amides from carboxylic acids. The process is general for the preparation of Weinreb amides from a variety of carboxylic acids. The reaction was also applicable to the preparation of α-amino Weinreb amides and proceeded without deprotection of the N-Fmoc protecting group or racemization of the stereogenic centers. N-Methoxy-N-methyl amides, or Weinreb amides, have been widely used as versatile synthetic intermediates in organic syntheses. These amides serve as excellent acylating agents for organolithium or organomagnesium reagents and as robust aldehyde group equivalents. The utility of Weinreb amides has been extended to the preparation of N-protected amino aldehydes, useful intermediates for many chemoselective transformations in peptide chemistry

[Studies on interaction of acid-treated nanotube titanic acid and amino acids].

Science.gov (United States)

Zhang, Huqin; Chen, Xuemei; Jin, Zhensheng; Liao, Guangxi; Wu, Xiaoming; Du, Jianqiang; Cao, Xiang

2010-06-01

Nanotube titanic acid (NTA) has distinct optical and electrical character, and has photocatalysis character. In accordance with these qualities, NTA was treated with acid so as to enhance its surface activity. Surface structures and surface groups of acid-treated NTA were characterized and analyzed by Transmission Electron Microscope (TEM) and Fourier Transform Infrared Spectrometry (FT-IR). The interaction between acid-treated NTA and amino acids was investigated. Analysis results showed that the lengths of acid-treated NTA became obviously shorter. The diameters of nanotube bundles did not change obviously with acid-treating. Meanwhile, the surface of acid-treated NTA was cross-linked with carboxyl or esterfunction. In addition, acid-treated NTA can catch amino acid residues easily, and then form close combination.

Stereospecific synthesis of syn-α-oximinoamides by a three-component reaction of isocyanides, syn-chlorooximes, and carboxylic acids.

Science.gov (United States)

Pirali, Tracey; Mossetti, Riccardo; Galli, Simona; Tron, Gian Cesare

2011-07-15

A stereospecific multicomponent reaction among isocyanides, syn-chlorooximes, and carboxylic acids provides an efficient synthesis of biologically relevant syn-α-oximinoamides. © 2011 American Chemical Society

[14C]-radiolabeling of {[trans-(8β)]-6-methyl-1-(1-methylethyl) ergoline-8-carboxylic acid, 4-methoxycyclohexyl ester (Z)-2-buteneidioate (1:1)}

International Nuclear Information System (INIS)

Marzoni, G.; Wheeler, W.J.; Garbrecht, W.L.

1988-01-01

The 5HT 2 -receptor antagonist, [ 14 C]-labeled brace[trans-(8β)]-6-methyl-1-(1-methylethyl)ergoline-8-carboxylic acid, 4-methoxycyclohexyl ester (Z)-2-butenedioate (1:1)brace (LY281067) was synthesized from unlabeled 6-methyl-1-(1-methylethyl)ergoline-8-carboxylic acid. The [ 14 C] label was introduced into the carboxyl group attached to the 8 position of the ergoline nucleus. This site is stable to metabolism. The synthesis involves removal of an unlabeled carboxyl group and subsequent reinsertion of a [ 14 C]-labeled carboxyl group into the same position. The radiolabel is not introduced until near the end of the synthesis which allows for ease of handling and scale-up of intermediates. (author)

Organic acids in naturally colored surface waters

Science.gov (United States)

Lamar, William L.; Goerlitz, D.F.

1966-01-01

Most of the organic matter in naturally colored surface waters consists of a mixture of carboxylic acids or salts of these acids. Many of the acids color the water yellow to brown; however, not all of the acids are colored. These acids range from simple to complex, but predominantly they are nonvolatile polymeric carboxylic acids. The organic acids were recovered from the water by two techniques: continuous liquid-liquid extraction with n-butanol and vacuum evaporation at 50?C (centigrade). The isolated acids were studied by techniques of gas, paper, and column chromatography and infrared spectroscopy. About 10 percent of the acids recovered were volatile or could be made volatile for gas chromatographic analysis. Approximately 30 of these carboxylic acids were isolated, and 13 of them were individually identified. The predominant part of the total acids could not be made volatile for gas chromatographic analysis. Infrared examination of many column chromatographic fractions indicated that these nonvolatile substances are primarily polymeric hydroxy carboxylic acids having aromatic and olefinic unsaturation. The evidence suggests that some of these acids result from polymerization in aqueous solution. Elemental analysis of the sodium fusion products disclosed the absence of nitrogen, sulfur, and halogens.

Chemical rescue of the post-translationally carboxylated lysine mutant of allantoinase and dihydroorotase by metal ions and short-chain carboxylic acids.

Science.gov (United States)

Ho, Ya-Yeh; Huang, Yen-Hua; Huang, Cheng-Yang

2013-04-01

Bacterial allantoinase (ALLase) and dihydroorotase (DHOase) are members of the cyclic amidohydrolase family. ALLase and DHOase possess similar binuclear metal centers in the active site in which two metals are bridged by a post-translationally carboxylated lysine. In this study, we determined the effects of carboxylated lysine and metal binding on the activities of ALLase and DHOase. Although DHOase is a metalloenzyme, purified DHOase showed high activity without additional metal supplementation in a reaction mixture or bacterial culture. However, unlike DHOase, ALLase had no activity unless some specific metal ions were added to the reaction mixture or culture. Substituting the metal binding sites H59, H61, K146, H186, H242, or D315 with alanine completely abolished the activity of ALLase. However, the K146C, K146D and K146E mutants of ALLase were still active with about 1-6% activity of the wild-type enzyme. These ALLase K146 mutants were found to have 1.4-1.7 mol metal per mole enzyme subunit, which may indicate that they still contained the binuclear metal center in the active site. The activity of the K146A mutant of the ALLase and the K103A mutant of DHOase can be chemically rescued by short-chain carboxylic acids, such as acetic, propionic, and butyric acids, but not by ethanol, propan-1-ol, and imidazole, in the presence of Co2+ or Mn2+ ions. However, the activity was still ~10-fold less than that of wild-type ALLase. Overall, these results indicated that the 20 natural basic amino acid residues were not sufficiently able to play the role of lysine. Accordingly, we proposed that during evolution, the post-translational modification of carboxylated lysine in the cyclic amidohydrolase family was selected for promoting binuclear metal center self-assembly and increasing the nucleophilicity of the hydroxide at the active site for enzyme catalysis. This kind of chemical rescue combined with site-directed mutagenesis may also be used to identify a binuclear metal

Clozapine-carboxylic acid plasticized co-amorphous dispersions: Preparation, characterization and solution stability evaluation

Directory of Open Access Journals (Sweden)

Ali Ahmed Mahmoud Abdelhaleem

2015-06-01

Full Text Available This study addressed the possibility of forming of co-amorphous systems between clozapine (CZ and various carboxylic acid plasticizers (CAPs. The aim was to improve the solubility and oral bioavailability of clozapine. Co-amorphous dispersions were prepared using modified solvent evaporation methodology at drug/plasticizer stoichiometric ratios of 1:1, 1:1.5 and 1:2. Solid state characterization was performed using differential scanning calorimetry, X-ray diffraction and infra red spectroscopy. Highly soluble homogeneous co-amorphous dispersions were formed between clozapine and CAPs via hydrogen bonding. The co-amorphous dispersions formed with tartaric acid (1:2 showed the highest dissolution percentage (> 95 % in 20 minutes compared to pure crystalline CZ (56 %. Highly stable solutions were obtained from co-amorphous CZ-citric and CZ-tartaric acid at 1:1.5 molar ratio. The prepared dispersions suggest the possibility of peroral or sublingual administration of highly soluble clozapine at a reduced dose with the great chance to bypass the first pass metabolism.

Copper coordination polymers constructed from thiazole-5-carboxylic acid: Synthesis, crystal structures, and structural transformation

Energy Technology Data Exchange (ETDEWEB)

Meundaeng, Natthaya; Rujiwatra, Apinpus [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Prior, Timothy J., E-mail: t.prior@hull.ac.uk [Chemistry, University of Hull, Kingston upon Hull HU6 7RX (United Kingdom)

2017-01-15

We have successfully prepared crystals of thiazole-5-carboxylic acid (5-Htza) (L) and three new thiazole-5-carboxylate-based Cu{sup 2+} coordination polymers with different dimensionality, namely, 1D [Cu{sub 2}(5-tza){sub 2}(1,10-phenanthroline){sub 2}(NO{sub 3}){sub 2}] (1), 2D [Cu(5-tza){sub 2}(MeOH){sub 2}] (2), and 3D [Cu(5-tza){sub 2}]·H{sub 2}O (3). These have been characterized by single crystal X-ray diffraction and thermogravimetry. Interestingly, the 2D network structure of 2 can directly transform into the 3D framework of 3 upon removal of methanol molecules at room temperature. 2 can also undergo structural transformation to produce the same 2D network present in the known [Cu(5-tza){sub 2}]·1.5H{sub 2}O upon heat treatment for 2 h. This 2D network can adsorb water and convert to 3 upon exposure to air. - Highlights: • Rare examples of coordination polymers of thiazole-5-carboxylic acid were prepared. • Non-covalent interactions play a key role on the assembly of the complexes in solid state. • Structural transformation of a 2D framework to a 3D upon removal of methanol is observed.

Influence of indium-tin oxide surface structure on the ordering and coverage of carboxylic acid and thiol monolayers

International Nuclear Information System (INIS)

Cerruti, Marta; Rhodes, Crissy; Losego, Mark; Efremenko, Alina; Maria, Jon-Paul; Fischer, Daniel; Franzen, Stefan; Genzer, Jan

2007-01-01

This paper analyses the variability of self-assembled monolayers (SAMs) formation on ITO depending on the substrate surface features. In particular, we report on the formation of carboxylic acid- and thiol-based SAMs on two lots of commercially prepared indium-tin oxide (ITO) thin films. Contact angle measurements, electrochemical experiments, and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy showed that the quality of monolayers formed differed substantially between the two ITO batches. Only one of the two ITO substrates was capable of forming well-organized thiol- and carboxylic acid-based SAMs. In order to rationalize these observations, atomic force microscopy and x-ray diffraction analyses were carried out, and SAMs were prepared on ITO substrates fabricated by sputtering in our laboratories. An attempt was made to influence the film microstructure and surface morphology by varying substrate temperatures during ITO deposition. Good-quality thiol and carboxylic acid SAMs were obtained on one of the ITO substrates prepared in-house. While our characterization could not single out conclusively one specific parameter in ITO surface structure that could be responsible for good SAMs formation, we could point out homogeneous surface morphology as a relevant factor for the quality of the SAMs. Evidence was also found for ITO crystallographic orientation to be a parameter influencing SAMs organization

Effectiveness of carboxylic acids from Pichia membranifaciens against coffee rust

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Rosa Laura Andrade Melchor

Full Text Available ABSTRACT Coffee rust is a fungal disease that has affected every coffee-producing region in the world. Given that the effectivity of the protectant and systemic fungicides applied routinely to control the spread of the causative agent of the disease (Hemileia vastatrix has gradually diminished, besides are harmful to mammals and ecosystems, the objective of this work was to search for a mixture of harmless natural compounds with the potential to be applied in the field. So, a yeast strain producing a battery of long-chain carboxylic acids (CA with fungicide properties was isolated from soil of coffee crop and identified as Pichia membranifaciens by ITS sequencing. Culture conditions of the yeast were optimized and the CA in the solution were characterized by Gas Chromatography-Mass Spectrometry (GC-MS as ethyl formate (55.5 g L-1, octadecenoic acid (3.5 g L-1, propionic acid (7.2 g L-1, 3-(octadecanoyl-propionic acid (7.2 g L-1 and methyl acetate (8.4 g L-1. Randomized field studies were conducted in three different locations in Chiapas, México. Five treatments were tested including three concentrations of the CA solution (389, 584 and 778 ppm and copper oxychloride (5 000 ppm as conventional control. The initial coffee rust incidence averages varied between sites: Maravillas (3-9%, Santo Domingo (10-16% and Búcaro (16-22%. The treatments of CA solution proved to be effective at slowing down the progress of the rust disease even for the sites where initial incidence was high. Likewise, the CA solution reduced the viability of H. vastatrix spores, as assessed by fluorescence microscopy.

Enriched surface acidity for surfactant-free suspensions of carboxylated carbon nanotubes purified by centrifugation

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Elizabeth I. Braun

2016-06-01

Full Text Available It is well known that surfactant-suspended carbon nanotube (CNT samples can be purified by centrifugation to decrease agglomerates and increase individually-dispersed CNTs. However, centrifugation is not always part of protocols to prepare CNT samples used in biomedical applications. Herein, using carboxylated multi-walled CNTs (cMWCNTs suspended in water without a surfactant, we developed a Boehm titrimetric method for the analysis of centrifuged cMWCNT suspensions and used it to show that the surface acidity of oxidized carbon materials in aqueous cMWCNT suspensions was enriched by ∼40% by a single low-speed centrifugation step. This significant difference in surface acidity between un-centrifuged and centrifuged cMWCNT suspensions has not been previously appreciated and is important because the degree of surface acidity is known to affect the interactions of cMWCNTs with biological systems.

Derivatization of carboxylic acids with 4-APEBA for detection by positive-ion LC-ESI-MS(/MS) applied for the analysis of prostanoids and NSAID in urine

NARCIS (Netherlands)

Kretschmer, A.; Giera, M.A.; Wijtmans, M.; de Vries, L.; Lingeman, H.; Irth, H.; Niessen, W.M.A.

2011-01-01

In order to develop a generic positive ionization ESI LC-MS method for a variety of interesting substance classes, a new derivatization strategy for carboxylic acids was developed. The carboxylic acid group is labeled with the bromine containing 4-APEBA reagent based on carbodiimide chemistry. The

Structural and thermal properties of carboxylic acid functionalized polythiophenes

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Ariane de França Mescoloto

2014-01-01

Full Text Available Polythiophenes functionalized with polar groups at the end of side-chain have emerged as an alternative method to obtain good compatibility between this class of conjugated polymers and electron acceptor compounds. The aim is to prevent phase segregation and to improve the efficiency of the polythiophene technological devices. However, homopolymers synthesized from thiophene rings with high polar groups at the end of the side-chain, such as hydroxyl and carboxylic acid groups, are poorly soluble in common volatile organic solvents. We report on a systematic preparation of copolymers of 3-hexylthiophene (HT and thiophene-3-acetic acid (TAA, using different feed ratios. The chemical structures of the copolymers were confirmed by FTIR and ¹H-NMR. The TAA content in these copolymers were 33, 38 and 54 mol %. HPSEC results did not show any remarkable correlation with TAA contents in the copolymers. In contrast, the thermal analyses showed a decrease in the thermal stability and an increase in rigidity of their backbones, for the copolymers with high amounts of TAA. The solubility and optical property of copolymers were also related to the TAA contents. Thus, the properties of these copolymers can be modulated by a simple control of feed ratio of TAA in the copolymerization.

Preparation of fulvic acid and low-molecular organic acids by oxidation of weathered coal humic acid

Energy Technology Data Exchange (ETDEWEB)

Shinozuka, T.; Ito, A.; Sasaki, O.; Yazawa, Y.; Yamaguchi, T. [Chiba Institute of Technolgy, Chiba (Japan). Dept. of Industrial Chemistry

2002-07-01

Weathered coal contains much humic acid and a little fulvic acid. Therefore, the production of fulvic acid, the most valuable humic substance because of its water-solubility, was examined by ozone and hydrogen peroxide oxidation of humic acid extracted form Xinjiang (China) weathered coal. The resulting products of the oxidation were water soluble fulvic acid and organic acids, mainly formic acid and oxalic acid. The product yield of fulvic acid was 20 (C%) and that of organic acids were 39 (C%) for formic and acid 13 (C%) for oxalic acid. The formed fulvic acid showed a higher content of oxygen and carboxyl groups, than those of the extracted one from the original weathered coal.

Immobilization of dendrimers on Si-C linked carboxylic acid-terminated monolayers on silicon(111)

International Nuclear Information System (INIS)

Boecking, Till; Wong, Elicia L.S.; James, Michael; Watson, Jolanta A.; Brown, Christopher L.; Chilcott, Terry C.; Barrow, Kevin D.; Coster, Hans G.L.

2006-01-01

Poly(amidoamine) dendrimers were attached to activated undecanoic acid monolayers, covalently linked to smooth silicon surfaces via Si-C bonds. The resulting ultra-thin dendrimer films were characterized by X-ray photoelectron spectroscopy (XPS), X-ray reflectometry (XR) and atomic force microscopy (AFM). XPS results suggested amide bond formation between the dendrimer and the surface carboxylic acid groups. XR yielded thicknesses of 10 A for the alkyl region of the undecanoic acid monolayer and 12 A for the dendrimer layer, considerably smaller than the diameter of these spherical macromolecules in solution. This was consistent with AFM images showing collapsed dendrimers on the surface. It was concluded that the deformation arose from a large number of amine groups on the surface of each dendrimer reacting efficiently with the activated surface, whereby the dendrimers can deform to fill voids while spreading over the activated surface to form a homogeneous macromolecular layer

Method for the determination of carboxylic acids in industrial effluents using dispersive liquid-liquid microextraction with injection port derivatization gas chromatography-mass spectrometry.

Science.gov (United States)

Makoś, Patrycja; Fernandes, Andre; Boczkaj, Grzegorz

2017-09-29

The paper presents a new method for the determination of 15 carboxylic acids in samples of postoxidative effluents from the production of petroleum bitumens using ion-pair dispersive liquid-liquid microextraction and gas chromatography coupled to mass spectrometry with injection port derivatization. Several parameters related to the extraction and derivatization efficiency were optimized. Under optimized experimental conditions, the obtained limit of detection and quantification ranged from 0.0069 to 1.12μg/mL and 0.014 to 2.24μg/mL, respectively. The precision (RSD ranged 1.29-6.42%) and recovery (69.43-125.79%) were satisfactory. Nine carboxylic acids at concentrations ranging from 0.10μg/mL to 15.06μg/mL were determined in the raw wastewater and in samples of effluents treated by various oxidation methods. The studies revealed a substantial increase of concentration of benzoic acids, in samples of wastewater after treatment, which confirms the need of carboxylic acids monitoring during industrial effluent treatment processes. Copyright © 2017 Elsevier B.V. All rights reserved.

High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T., E-mail: ktlim@pknu.ac.kr [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2015-03-30

Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.

Characterisation and application of new carboxylic acid-functionalised ruthenium complexes as dye-sensitisers for solar cells

DEFF Research Database (Denmark)

Duprez, Virginie; Biancardo, Matteo; Krebs, Frederik C

2007-01-01

A series of ruthenium complexes with and without TiO2, anchoring carboxylic acid groups have been synthesised and characterised using nuclear magnetic resonance (NMR), UV-vis and luminescence. These complexes were adsorbed on thin films of the wide band-gap semiconductor anatase and were tested a...

Structure-Activity Relationship Study of Ionotropic Glutamate Receptor Antagonist (2S,3R)-3-(3-Carboxyphenyl)pyrrolidine-2-carboxylic Acid

DEFF Research Database (Denmark)

Krogsgaard-Larsen, Niels; Storgaard, Morten; Møller, Charlotte

2015-01-01

Herein we describe the first structure-activity relationship study of the broad-range iGluR antagonist (2S,3R)-3-(3-carboxyphenyl)pyrrolidine-2-carboxylic acid (1) by exploring the pharmacological effect of substituents in the 4, 4', or 5' positions and the bioisosteric substitution of the distal...... carboxylic acid for a phosphonic acid moiety. Of particular interest is a hydroxyl group in the 4' position 2a which induced a preference in binding affinity for homomeric GluK3 over GluK1 (Ki = 0.87 and 4.8 μM, respectively). Two X-ray structures of ligand binding domains were obtained: 2e in GluA2-LBD...... and 2f in GluK1-LBD, both at 1.9 Å resolution. Compound 2e induces a D1-D2 domain opening in GluA2-LBD of 17.3-18.8° and 2f a domain opening in GluK1-LBD of 17.0-17.5° relative to the structures with glutamate. The pyrrolidine-2-carboxylate moiety of 2e and 2f shows a similar binding mode as kainate...

The acidic functional groups of humic acid

Energy Technology Data Exchange (ETDEWEB)

Shanxiang, Li; Shuhe, Sun; Zhai Zongxi, Wu Qihu

1983-09-01

The acidic functional groups content, pK value, DELTAH and DELTAS of humic acid (HA) and nitro-humic acid (NHA) were determined by potentiometry, conductometry and calorimetric titration. The thermodynamic parameters of carboxylic groups and phenolic hydroxyl groups of humic acid are similar to that of simple hydroxy-benzoic acid. The configuration sites of acidic functional groups in humic acid from different coals are different. The carbonyl groups on aromatic rings are probably ortho to phenolic -OH for HA and NHA extracted from Huangxian's brown coal and Japanese lignite, while those from Lingshi's weathered coal are not. The weak -COOH groups of the latter possess higher chemical activity. The -COOH content in HA increases, phenolic -OH group decreases and the chemical acidity of acidic functional groups increases when HA is oxidized by nitric acid. (14 refs.)

Meso-ester and carboxylic acid substituted BODIPYs with far-red and near-infrared emission for bioimaging applications

KAUST Repository

Ni, Yong; Zeng, Lintao; Kang, Namyoung; Huang, Kuo-Wei; Wang, Liang; Zeng, Zebing; Chang, Young-Tae; Wu, Jishan

2014-01-01

-6) become partially soluble in water, and their absorptions and emissions are located in the far-red or near-infrared region. Three synthetic approaches are attempted to access the meso-carboxylic acid (COOH)-substituted BODIPYs 7 and 8 from the meso

Surface properties of calcium and magnesium oxide nanopowders grafted with unsaturated carboxylic acids studied with inverse gas chromatography.

Science.gov (United States)

Maciejewska, Magdalena; Krzywania-Kaliszewska, Alicja; Zaborski, Marian

2012-09-28

Inverse gas chromatography (IGC) was applied at infinite dilution to evaluate the surface properties of calcium and magnesium oxide nanoparticles and the effect of surface grafted unsaturated carboxylic acid on the nanopowder donor-acceptor characteristics. The dispersive components (γ(s)(D)) of the free energy of the nanopowders were determined by Gray's method, whereas their tendency to undergo specific interactions was estimated based on the electron donor-acceptor approach presented by Papirer. The calcium and magnesium oxide nanoparticles exhibited high surface energies (79 mJ/m² and 74 mJ/m², respectively). Modification of nanopowders with unsaturated carboxylic acids decreased their specific adsorption energy. The lowest value of γ(s)(D) was determined for nanopowders grafted with undecylenic acid, approximately 55 mJ/m². The specific interactions were characterised by the molar free energy (ΔG(A)(SP)) and molar enthalpy (ΔH(A)(SP)) of adsorption as well as the donor and acceptor interaction parameters (K(A), K(D)). Copyright © 2012 Elsevier B.V. All rights reserved.

Megasphaera hexanoica sp. nov., a medium-chain carboxylic acid-producing bacterium isolated from a cow rumen.

Science.gov (United States)

Jeon, Byoung Seung; Kim, Seil; Sang, Byoung-In

2017-07-01

Strain MHT, a strictly anaerobic, Gram-stain-negative, non-spore-forming, spherical coccus or coccoid-shaped microorganism, was isolated from a cow rumen during a screen for hexanoic acid-producing bacteria. The microorganism grew at 30-40 °C and pH 5.5-7.5 and exhibited production of various short- and medium-chain carboxylic acids (acetic acid, butyric acid, pentanoic acid, isobutyric acid, isovaleric acid, hexanoic acid, heptanoic acid and octanoic acid), as well as H2 and CO2 as biogas. Phylogenetic analysis based on 16S rRNA gene sequencing demonstrated that MHT represents a member of the genus Megasphaera, with the closest relatives being Megapsphaera indica NMBHI-10T (94.1 % 16S rRNA sequence similarity), Megasphaera elsdenii DSM 20460T (93.8 %) and Megasphaera paucivorans DSM 16981T (93.8 %). The major cellular fatty acids produced by MHT included C12 : 0, C16 : 0, C18 : 1cis 9, and C18 : 0, and the DNA G+C content of the MHT genome is 51.8 mol%. Together, the distinctive phenotypic and phylogenetic characteristics of MHT indicate that this microorganism represents a novel species of the genus Megasphaera, for which the name Megasphaera hexanoica sp. nov. is herein proposed. The type strain of this species is MHT (=KCCM 43214T=JCM 31403T).

Investigations of the reactivity of pyridine carboxylic acids with diazodiphenylmethane in protic and aprotic solvents.

Directory of Open Access Journals (Sweden)

ALEKSANDAR D. MARINKOVIC

2005-04-01

Full Text Available Rate constants for the reaction of diazodiphenylmethane with isomeric pyridine carboxylic acids were determined in chosen protic and aprotic solvents at 30 °C, using the well known UV spectrophotometric method. The values of the rate constants of the investigated acids in protic solvents were higher than those in aprotic solvents. The second order rate constants were correlated with solvent parameters using the Kamlet-Taft solvatochromic equation in the form: log k = log k0 + sp* + aa + bb . The correlation of the obtained kinetic data were performed by means of multiple linear regression analysis taking appropriate solvent parameters. The signs of the equation coefficients were in agreement with the postulated reaction mechanism. The mode of the influence of the solvent on the reaction rate in all the investigated acids are discussed on the basis of the correlation results.

Aldehydes, ketones, and carboxylic acids formed radiolytically in aqueous solutions of cyanides and simple nitriles

International Nuclear Information System (INIS)

Negron-Mendoza, A.; Draganic, Z.D.; Navarro-Gonzalez, R.; Graganic, I.G.

1983-01-01

A systematic search for aldehydes, ketones, and carboxylic acids was carried out in aqueous solutions of HCN, NH 4 CN, CH 3 CN, and C 2 H 4 CN, that had received multikilogray doses of 60 Co γ radiation. About 30 radiolytic products were identified, among them a large variety of dicarboxylic and tricarboxylic acids. Some of them might be of significant interest in molecular evolution studies of prebiotic processes. They originate in the free-radical-initiated chemical reactions where the additional oligomerization processes are particularly important. Most of the radiolytic products appear in both cyanides and nitriles and point to the importance of reactions involving the carbon-nitrogen triple bond

Chemo-enzymatic Baeyer-Villiger oxidation of 4-methylcyclohexanone via kinetic resolution of racemic carboxylic acids: direct access to enantioenriched lactone.

Science.gov (United States)

Drożdż, Agnieszka; Chrobok, Anna

2016-01-21

A new method for the asymmetric chemo-enzymatic Baeyer-Villiger oxidation of prochiral 4-methylcyclohexanone to (R)-4-methylcaprolactone in the presence of (±)-4-methyloctanoic acid, Candida Antarctica lipase B and 30% aq. H2O2 has been developed. A mechanism for the asymmetric induction based on kinetic resolution of racemic carboxylic acids is proposed.

Gas chromatographic-mass spectrometric investigation of n-alkanes and carboxylic acids in bottom sediments of the northern Caspian Sea

Science.gov (United States)

Kenzhegaliev, Akimgali; Zhumagaliev, Sagat; Kenzhegalieva, Dina; Orazbayev, Batyr

2018-03-01

Prior to the start of experimental oil production in the Kashagan field (northern part of the Caspian Sea), n-alkanes and carboxylic acids contained in samples obtained from bottom sediments in the area of artificial island "D" were investigated by gas chromatography-mass spectrometry. Concentrations of 10 n-alkanes (composed of C10-C13, C15-C20) and 11 carboxylic acids (composed of C6-C12, C14-C16) were identified and measured. Concentrations of individual alkanes and carboxylic acids in bottom sediments of the various samples varied between 0.001 ÷ 0.88 μg/g and 0.001 ÷ 1.94 μg/g, respectively. Mass spectra, in particular the M+ molecular ion peak and the most intense peaks of fragment ions, are given. The present study illustrates the stability of molecular ions to electronic ionisation and the main fragment ions to the total ion current and shows that the initial fragmentation of alkanes implies radical cleavage of C2H5 rather than CH3. All aliphatic monocarboxylic acids studied were characterised by McLafferty rearrangement leading to the formation of F4 cation-radical with m/z 60 and F3 cation-radical with m/z 88 in the case of ethylhexanoic acid. The formation of oxonium ions presents another important aspect of acid fragmentation. Using mass numbers of oxonium ions and rearrangement ions allows determination of the substitution character in α- and β- C atoms. The essence of our approach is to estimate the infiltration of hydrocarbon fluids from the enclosing formation into sea water, comprising an analysis of derivatives of organic compounds in bottom sediments. Thus, concentrations of derived organic molecules can serve as a basis for estimates of the depth at which hydrocarbon fluids leak, i.e., to serve as an auxiliary technique in the search for hydrocarbon deposits and to repair well leaks.

Investigation of supramolecular synthons and structural characterisation of aminopyridine-carboxylic acid derivatives.

Science.gov (United States)

Hemamalini, Madhukar; Loh, Wan-Sin; Quah, Ching Kheng; Fun, Hoong-Kun

2014-01-01

Co-crystal is a structurally homogeneous crystalline material that contains two or more neutral building blocks that are present in definite stoichiometric amounts. The main advantage of co-crystals is their ability to generate a variety of solid forms of a drug that have distinct physicochemical properties from the solid co-crystal components. In the present investigation, five co-crystals containing 2-amino-6-chloropyridine (AMPY) moiety were synthesized and characterized. The crystal structure of 2-amino-6-chloropyridine (AMPY) (I), and the robustness of pyridine-acid supramolecular synthon were discussed in four stoichiometry co-crystals of AMPY…BA (II), AMPY…2ABA (III), AMPY…3CLBA (IV) and AMPY…4NBA (V). The abbreviated designations used are benzoic acid (BA), 2-aminobenzoic acid (2ABA), 3-chlorobenzoic acid (3CLBA) and 4-nitrobenzoic acid (4NBA). All the crystalline materials have been characterized by (1)HNMR, (13)CNMR, IR, photoluminescence, TEM analysis and X-ray diffraction. The supramolecular assembly of each co-crystal is analyzed and discussed. Extensive N---H · · · N/N---H · · · O/O---H · · · N hydrogen bonds are found in (I-V), featuring different supramolecular synthons. In the crystal structure, for compound (I), the 2-amino-6-chloropyridine molecules are linked together into centrosymmetric dimers by hydrogen bonds to form homosynthon, whereas for compounds (II-V), the carboxylic group of the respective acids (benzoic acid, 2-aminobenzoic acid, 3-chlorobenzoic acid and 4-nitrobenzoic acid) interacts with pyridine molecule in a linear fashion through a pair of N---H · · · O and O---H · · · N hydrogen bonds, generating cyclic hydrogen-bonded motifs with the graph-set notation [Formula: see text] , to form heterosynthon. In compound (II), another intermolecular N---H · · · O hydrogen bonds further link these heterosynthons into zig-zag chains. Whereas in compounds (IV) and (V

Synthesis, characterization and crystal structure of (2RS,4R)-2-(2-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid

Science.gov (United States)

Muche, Simon; Müller, Matthias; Hołyńska, Małgorzata

2018-03-01

The condensation reaction of ortho-vanillin and L-cysteine leads to formation of a racemic mixture of (2RS,4R)-2-(2-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid and not, as reported in the available literature, to a Schiff base. The racemic mixture was fully characterized by 1D and 2D NMR techniques, ESI-MS and X-ray diffraction. Addition of ZnCl2 led to formation of crystals in form of colorless needles, suitable for X-ray diffraction studies. The measured crystals were identified as the diastereomer (2R,4R)-2-(2-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid 1. The bulk material is racemic. Thiazolidine exists as zwitterion in solid state, as indicated by the crystal structure.

Thermochemistry of aqueous pyridine-3-carboxylic acid (nicotinic acid)

Energy Technology Data Exchange (ETDEWEB)

Goncalves, Elsa M. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto Politecnico de Setubal, ESTBarreiro, Rua Americo da Silva Marinho, 2839-001 Lavradio (Portugal); Rego, Talita S. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Minas da Piedade, Manuel E., E-mail: memp@fc.ul.p [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal)

2011-06-15

Research highlights: {yields} We determined the {Delta}{sub sol}H{sub m} of solid nicotinic acid (NA) in water by solution calorimetry. {yields} We determined {Delta}{sub dil}H{sub m} of an aqueous nicotinic acid solution by flow calorimetry. {yields} We determined (aq, {infinity}) for the 3 NA species involved in acid/base equilibria. {yields} We determined the enthalpy of formation of NA(aq) under saturation conditions.. - Abstract: The molar enthalpy of solution of solid nicotinic acid (NA) at T = 298.15 K, to give an aqueous solution of molality m = 3.748 . 10{sup -3} mol {center_dot} kg{sup -1}, was determined as {Delta}{sub sol}H{sub m} = (19,927 {+-} 48) J {center_dot} mol{sup -1}, by solution calorimetry. Enthalpies of dilution, {Delta}{sub dil}H{sub m}, of 0.1005 mol {center_dot} kg{sup -1} aqueous nicotinic acid to yield final solutions with molality in the approximate range (0.03 to 0.09) mol {center_dot} kg{sup -1} were also measured by flow calorimetry. Combining the two sets of data and the results of pH measurements, with values of proton dissociation enthalpies and {Delta}{sub f}H{sub m}{sup 0}(NA, cr) selected from the literature, it was possible to derive the standard molar enthalpies of formation of the three nicotinic acid species involved in protonation/deprotonation equilibria, at infinite dilution: {Delta}{sub f}H{sub m}{sup 0}(HN{sup +}C{sub 5}H{sub 4}COOH.{infinity}H{sub 2}O,aq) = (328.2 {+-} 1.2) kJ {center_dot} mol{sup -1}, {Delta}{sub f}H{sub m}{sup 0}(HN{sup +}C{sub 5}H{sub 4}COO{sup -}.{infinity}H{sub 2}O,aq) = (325.0 {+-} 1.2) kJ {center_dot} mol{sup -1}, and {Delta}{sub f}H{sub m}{sup 0}(NC{sub 5}H{sub 4}COO{sup -}.{infinity}H{sub 2}O,aq) = (313.7 {+-} 1.2) kJ {center_dot} mol{sup -1}. Finally, the enthalpy of solution of nicotinic acid at T = 298.15 K, under saturation conditions (m = 0.138 mol {center_dot} kg{sup -1}), and the standard molar enthalpy of formation of the corresponding solution could also be obtained as {Delta

Activation of the Glutamic Acid-Dependent Acid Resistance System in Escherichia coli BL21(DE3) Leads to Increase of the Fatty Acid Biotransformation Activity.

Science.gov (United States)

Woo, Ji-Min; Kim, Ji-Won; Song, Ji-Won; Blank, Lars M; Park, Jin-Byung

The biosynthesis of carboxylic acids including fatty acids from biomass is central in envisaged biorefinery concepts. The productivities are often, however, low due to product toxicity that hamper whole-cell biocatalyst performance. Here, we have investigated factors that influence the tolerance of Escherichia coli to medium chain carboxylic acid (i.e., n-heptanoic acid)-induced stress. The metabolic and genomic responses of E. coli BL21(DE3) and MG1655 grown in the presence of n-heptanoic acid indicated that the GadA/B-based glutamic acid-dependent acid resistance (GDAR) system might be critical for cellular tolerance. The GDAR system, which is responsible for scavenging intracellular protons by catalyzing decarboxylation of glutamic acid, was inactive in E. coli BL21(DE3). Activation of the GDAR system in this strain by overexpressing the rcsB and dsrA genes, of which the gene products are involved in the activation of GadE and RpoS, respectively, resulted in acid tolerance not only to HCl but also to n-heptanoic acid. Furthermore, activation of the GDAR system allowed the recombinant E. coli BL21(DE3) expressing the alcohol dehydrogenase of Micrococcus luteus and the Baeyer-Villiger monooxygenase of Pseudomonas putida to reach 60% greater product concentration in the biotransformation of ricinoleic acid (i.e., 12-hydroxyoctadec-9-enoic acid (1)) into n-heptanoic acid (5) and 11-hydroxyundec-9-enoic acid (4). This study may contribute to engineering E. coli-based biocatalysts for the production of carboxylic acids from renewable biomass.

Activation of the Glutamic Acid-Dependent Acid Resistance System in Escherichia coli BL21(DE3 Leads to Increase of the Fatty Acid Biotransformation Activity.

Directory of Open Access Journals (Sweden)

Ji-Min Woo

Full Text Available The biosynthesis of carboxylic acids including fatty acids from biomass is central in envisaged biorefinery concepts. The productivities are often, however, low due to product toxicity that hamper whole-cell biocatalyst performance. Here, we have investigated factors that influence the tolerance of Escherichia coli to medium chain carboxylic acid (i.e., n-heptanoic acid-induced stress. The metabolic and genomic responses of E. coli BL21(DE3 and MG1655 grown in the presence of n-heptanoic acid indicated that the GadA/B-based glutamic acid-dependent acid resistance (GDAR system might be critical for cellular tolerance. The GDAR system, which is responsible for scavenging intracellular protons by catalyzing decarboxylation of glutamic acid, was inactive in E. coli BL21(DE3. Activation of the GDAR system in this strain by overexpressing the rcsB and dsrA genes, of which the gene products are involved in the activation of GadE and RpoS, respectively, resulted in acid tolerance not only to HCl but also to n-heptanoic acid. Furthermore, activation of the GDAR system allowed the recombinant E. coli BL21(DE3 expressing the alcohol dehydrogenase of Micrococcus luteus and the Baeyer-Villiger monooxygenase of Pseudomonas putida to reach 60% greater product concentration in the biotransformation of ricinoleic acid (i.e., 12-hydroxyoctadec-9-enoic acid (1 into n-heptanoic acid (5 and 11-hydroxyundec-9-enoic acid (4. This study may contribute to engineering E. coli-based biocatalysts for the production of carboxylic acids from renewable biomass.

Determination of dissociation constants or propionic acid and lactic acid (2-hydroxypropionic acid) by potentiometry and conductometry

International Nuclear Information System (INIS)

Saeeduddin; Khanzada, A.W.K.

2004-01-01

Dissociation constants of propionic acid and 2-hydroxypropionic acid (lactic acid) have been studied at different temperatures between 25 to 50 deg. C interval. Propionic acid is analyzed by conductometry while 2-hydroxypropionic acid is analyzed by potentiometry. Both investigated compounds are symmetrical carboxylic acids having same length of carbon chain but are markedly different in ionic behavior. We were interested to see how the hydroxyl group (-OH) induction in propionic acid affects on pKa values of 2-hydroxypropionic acid. We observed that as temperature increases pKa values increase. The increase is observed for both the investigated compounds. PKa values of 2-hydroxypropionic acid are lower as compared to propionic acid because of electron withdrawing (-OH). (author)

Nanoparticles modified with multiple organic acids

Science.gov (United States)

Cook, Ronald Lee (Inventor); Luebben, Silvia DeVito (Inventor); Myers, Andrew William (Inventor); Smith, Bryan Matthew (Inventor); Elliott, Brian John (Inventor); Kreutzer, Cory (Inventor); Wilson, Carolina (Inventor); Meiser, Manfred (Inventor)

2007-01-01

Surface-modified nanoparticles of boehmite, and methods for preparing the same. Aluminum oxyhydroxide nanoparticles are surface modified by reaction with selected amounts of organic acids. In particular, the nanoparticle surface is modified by reactions with two or more different carboxylic acids, at least one of which is an organic carboxylic acid. The product is a surface modified boehmite nanoparticle that has an inorganic aluminum oxyhydroxide core, or part aluminum oxyhydroxide core and a surface-bonded organic shell. Organic carboxylic acids of this invention contain at least one carboxylic acid group and one carbon-hydrogen bond. One embodiment of this invention provides boehmite nanoparticles that have been surface modified with two or more acids one of which additional carries at least one reactive functional group. Another embodiment of this invention provides boehmite nanoparticles that have been surface modified with multiple acids one of which has molecular weight or average molecular weight greater than or equal to 500 Daltons. Yet, another embodiment of this invention provides boehmite nanoparticles that are surface modified with two or more acids one of which is hydrophobic in nature and has solubility in water of less than 15 by weight. The products of the methods of this invention have specific useful properties when used in mixture with liquids, as filler in solids, or as stand-alone entities.

Nanoparticles modified with multiple organic acids

Science.gov (United States)

Cook, Ronald Lee; Luebben, Silvia DeVito; Myers, Andrew William; Smith, Bryan Matthew; Elliott, Brian John; Kreutzer, Cory; Wilson, Carolina; Meiser, Manfred

2007-07-17

Surface-modified nanoparticles of boehmite, and methods for preparing the same. Aluminum oxyhydroxide nanoparticles are surface modified by reaction with selected amounts of organic acids. In particular, the nanoparticle surface is modified by reactions with two or more different carboxylic acids, at least one of which is an organic carboxylic acid. The product is a surface modified boehmite nanoparticle that has an inorganic aluminum oxyhydroxide core, or part aluminum oxyhydroxide core and a surface-bonded organic shell. Organic carboxylic acids of this invention contain at least one carboxylic acid group and one carbon-hydrogen bond. One embodiment of this invention provides boehmite nanoparticles that have been surface modified with two or more acids one of which additional carries at least one reactive functional group. Another embodiment of this invention provides boehmite nanoparticles that have been surface modified with multiple acids one of which has molecular weight or average molecular weight greater than or equal to 500 Daltons. Yet, another embodiment of this invention provides boehmite nanoparticles that are surface modified with two or more acids one of which is hydrophobic in nature and has solubility in water of less than 15 by weight. The products of the methods of this invention have specific useful properties when used in mixture with liquids, as filler in solids, or as stand-alone entities.

Synthesis and complexation properties towards uranyl cation of carboxylic acid derivatives of p-tert-butyl-calix[6]arene

International Nuclear Information System (INIS)

Souane, R.

2005-03-01

In the fuel reprocessing plants radioactive metals, and more particularly, uranium in UO 2 2+ form in the various installations, have many varied physico-chemical forms and there is a risk of exposure and internal contamination in the nuclear industry. It is necessary to exert a medical control to ensure the protection of the health of the workers. This medical control is done by dosing uranyl cation in the urine of the exposed people. This work forms part of this context. Indeed, we prepared a ligand able to complex the ion uranyl and which is also to be grafted on a solid support. In the family of calixarenes, the calix[6]arenes functionalized by three or four carboxylic functions were selected like chelating molecules of the ion uranyl. The properties of complexation of these calixarenes were studied by potentiometry in methanol, under these conditions balances of protonation and complexation were determined and the constant partners were obtained using the Hyperquad program. We synthesized tri-carboxylic calix[6]arenes comprising of the groupings nitro (NO 2 ) in para position of phenol in order to see the influence of a substitution in para position on the complexation. We also synthesized calix[6]arenes tetra-carboxylic in order to show the role of an additional carboxylic acid grouping. The potentiometric study determined thermodynamic parameters of protonation and complexation of carboxylic calix[6]arenes. The results of the complexation highlighted which complex UO 2 L corresponding to the ligand para-tert-butyl-calix[6]arene tetra-acid is more stable than that corresponding to the ligand mono-nitro calix[6]arene tri-acid (ΔlogΒ110 = 4.3), and than the effect of the groupings nitro in para position has low influence on the complexation of UO 2 2+ . This makes it possible to consider as possible the grafting of the calix[6]arenes which one knows the behaviour of trapping. To this end we synthesized the ligand 23. (author)

A rapid microwave induced synthesis of [carboxyl-14C]-nicotinic acid (vitamin B3) and [carbonyl-14C]-nicotinamide using K14CN

International Nuclear Information System (INIS)

Ravi, S.; Mathew, K.M.; Sivaprasad, N.

2008-01-01

Microwave assisted direct aromatic substitution of 3-bromopyridine with K 14 CN as the cyanide source and catalytic amount of tetrabutylammonium bromide afforded [3- 14 C]-cyanopyridine 3 in 90% yield. Microwave assisted hydrolysis of 3 with a mixture of concentrated hydrochloric acid and propionic acid afforded [carboxyl- 14 C]-nicotinic acid in 95% yield whereas microwave assisted hydrolysis of 3 with a mixture of concentrated sulfuric acid and propionic acid afforded [carbonyl- 14 C]-nicotinamide in 85% yield. (author)

Determination of the Cyanide Metabolite 2-Aminothiazoline-4-Carboxylic Acid in Urine and Plasma by Gas Chromatography-Mass Spectrometry

National Research Council Canada - National Science Library

Logue, Brian A; Kirschten, Nicholas P; Petrikovics, Ilona; Moser, Matthew A; Rockwood, Gary A; Baskin, Steven I

2005-01-01

The cyanide metabolite 2-aminothiazoline.4-carboxylic acid (ATCA) is a promising biomarker for cyanide exposure because of its stability and the limitations of direct determination of cyanide and more abundant cyanide metabolites...

Comparative hepatotoxicity of 6:2 fluorotelomer carboxylic acid and 6:2 fluorotelomer sulfonic acid, two fluorinated alternatives to long-chain perfluoroalkyl acids, on adult male mice.

Science.gov (United States)

Sheng, Nan; Zhou, Xiujuan; Zheng, Fei; Pan, Yitao; Guo, Xuejiang; Guo, Yong; Sun, Yan; Dai, Jiayin

2017-08-01

Due to their structural similarities, 6:2 fluorotelomer sulfonic acid (6:2 FTSA) and 6:2 fluorotelomer carboxylic acid (6:2 FTCA) are often used as alternatives to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), respectively. With limited health risk data and 6:2 FTSA detection in water and sludge, the toxicity of these chemicals is of growing concern. Here, adult male mice were exposed with 5 mg/kg/day of 6:2 FTCA or 6:2 FTSA for 28 days to investigate their hepatotoxicological effects. In contrast to 6:2 FTCA, 6:2 FTSA was detected at high and very high levels in serum and liver, respectively, demonstrating bioaccumulation potential and slow elimination. Furthermore, 6:2 FTSA induced liver weight increase, inflammation, and necrosis, whereas 6:2 FTCA caused no obvious liver injury, with fewer significantly altered genes detected compared with that of 6:2 FTSA (39 vs. 412). Although PFOA and PFOS commonly activate peroxisome proliferator-activated receptor α (PPARα), 6:2 FTSA induced an increase in PPARγ and related proteins, but not in lipid metabolism-related genes such as PPARα. Our results showed that 6:2 FTCA and 6:2 FTSA exhibited weak and moderate hepatotoxicity, respectively, compared with that reported for legacies PFOA and PFOS.

Electrochemical properties of polyolefin nonwoven fabric modified with carboxylic acid group for battery separator

Energy Technology Data Exchange (ETDEWEB)

Choi, Seong-Ho; Kang, Hae-Jeong; Ryu, Eun-Nyoung; Lee, Kwang-Pill E-mail: kplee@kyungpook.ac.kr

2001-07-01

Carboxylic acid group was introduced by radiation-induced grafting of acrylic acid (AAc) onto polyolefine nonwoven fabric (PNF), wherein the PNF comprises at least about 60% of a polyethylene having a melting temperature at {approx}132 deg. C and no more than about 40% of a second polypropylene having a lower melting temperature at {approx}162 deg. C, for a battery separator. The AAc-grafted PNF was characterized by XPS, SEM, DSC, TGA and porosimeter. The wetting speed, electrolyte retention, electrical resistance, and tensile strength were evaluated after grafting of AAc. It was found that the wetting speed, electrolyte retention, thickness, and ion-exchange capacity increased, whereas the electrical resistance decreased with increasing grafting yield. The tensile strength decreased with increasing grafting yield, whereas the elongation decreased with increasing grafting yield. (author)

Electrochemical properties of polyolefine nonwoven fabric modified with carboxylic acid group for battery separator

Energy Technology Data Exchange (ETDEWEB)

Choi, Seong-Ho; Park, Keung-Shik; Kang, Hae-Jeong; Ryu, Eun-Nyoung; Lee, Pill-Kwang [Department of Chemistry Graduate School, Kyungpook National University, Taegu (Korea)

2000-07-01

Carboxylic acid group was introduced by radiation-induced grafting of acrylic acid (AAc) onto polyolefine nonwoven fabric (PNF), wherein the PNF comprises at least about 60% of a polyethylene having a melting temperature at {approx}132degC and no more than about 40% of a second polypropylene having a lower melting temperature at {approx}162degC, for a battery separator. The AAc-grafted PNF was characterized by XPS, SEM, DSC, TGA and porosimeter. The wetting speed, electrolyte retention, electrical resistance, and tensile strength were evaluated after grafting of AAc. It was found that the wetting speed, electrolyte retention, thickness, and ion-exchange capacity increased, whereas the electrical resistance decreased with increasing grafting yield. The tensile strength decreased with increasing grafting yield, whereas the elongation decreased with increasing grafting yield. (author)

On the microstructure of organic solutions of mono-carboxylic acids: Combined study by infrared spectroscopy, small-angle neutron scattering and molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Eremin, Roman A., E-mail: era@jinr.ru [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Kholmurodov, Kholmirzo T. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); International University “Dubna”, Dubna 141980 (Russian Federation); Petrenko, Viktor I. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Taras Shevchenko National University of Kyiv, Kyiv 03022 (Ukraine); Rosta, László [Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest H-1525 (Hungary); Grigoryeva, Natalia A. [Faculty of Physics, Saint-Petersburg State University, 198504 Saint-Petersburg (Russian Federation); Avdeev, Mikhail V. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation)

2015-11-05

Highlights: • The model of the scattering particle for a reliable SANS analysis is proposed. • The structural parameters of saturated mono-carboxylic acids in solutions are obtained. • The differences in nematic transitions correlate to solvation peculiarities. - Abstract: The data of infrared spectroscopy (IR), molecular dynamics (MD) simulations and small-angle neutron scattering (SANS) have been combined to conclude about the nanoscale structural organization of organic non-polar solutions of saturated mono-carboxylic acids with different alkyl chain lengths for diluted solutions of saturated myristic (C14) and stearic (C18) acids in benzene and decalin. In particular, the degree of dimerization was found from the IR spectra. The structural anisotropy of the acids and their dimers was used in the treatment of the data of MD simulations to describe the solute–solvent interface in a cylindrical approximation and show its rather strong influence on SANS. The corresponding scattering length density profiles were used to fit the experimental SANS data comprising the information about the acid molecule isomerization. The SANS data from concentrated solutions showed a partial self-assembling of the acids within the nematic transition is different for two solvents due to lyophobic peculiarities.

Phenazine-1-carboxylic acid influences biofilm development and turnover of rhizobacterial biomass in a soil moisture-dependent manner

Science.gov (United States)

Rhizobacterial biofilm development influences terrestrial carbon and nitrogen cycles with ramifications for crop and soil health. Phenazine-1-carboxylic acid (PCA) is a redox-active metabolite produced by rhizobacteria in dryland wheat fields of Washington and Oregon, USA. PCA promotes biofilm dev...

Bioactivation of carboxylic acid compounds by UDP-Glucuronosyltransferases to DNA-damaging intermediates: role of glycoxidation and oxidative stress in genotoxicity.

Science.gov (United States)

Sallustio, Benedetta C; Degraaf, Yvette C; Weekley, Josephine S; Burcham, Philip C

2006-05-01

Nonenzymatic modification of proteins by acyl glucuronides is well documented; however, little is known about their potential to damage DNA. We have previously reported that clofibric acid undergoes glucuronidation-dependent bioactivation to DNA-damaging species in cultured mouse hepatocytes. The aim of this study was to investigate the mechanisms underlying such DNA damage, and to screen chemically diverse carboxylic acid drugs for their DNA-damaging potential in glucuronidation proficient murine hepatocytes. Cells were incubated with each aglycone for 18 h, followed by assessment of compound cytotoxicity using the MTT assay and evaluation of DNA damage using the Comet assay. Relative cytotoxic potencies were ketoprofen > diclofenac, benoxaprofen, nafenopin > gemfibrozil, probenecid > bezafibrate > clofibric acid. At a noncytotoxic (0.1 mM) concentration, only benoxaprofen, nafenopin, clofibric acid, and probenecid significantly increased Comet moments (P Clofibric acid and probenecid exhibited the greatest DNA-damaging potency, producing significant DNA damage at 0.01 mM concentrations. The two drugs produced maximal increases in Comet moment of 4.51 x and 2.57 x control, respectively. The glucuronidation inhibitor borneol (1 mM) abolished the induction of DNA damage by 0.5 mM concentrations of clofibric acid and probenecid. In an in vitro cell-free system, clofibric acid glucuronide was 10 x more potent than glucuronic acid in causing DNA strand-nicking, although both compounds showed similar rates of autoxidation to generate hydroxyl radicals. In cultured hepatocytes, the glycation inhibitor, aminoguanidine, and the iron chelator, desferrioxamine mesylate, inhibited DNA damage by clofibric acid, whereas the free radical scavengers Trolox and butylated hydroxytoluene, and the superoxide dismutase mimetic bis-3,5-diisopropylsalicylate had no effect. In conclusion, clinically relevant concentrations of two structurally unrelated carboxylic acids, probenecid and

Omega-3 carboxylic acids (Epanova): a review of its use in patients with severe hypertriglyceridemia.

Science.gov (United States)

Blair, Hannah A; Dhillon, Sohita

2014-10-01

Omega-3 carboxylic acids (Epanova) [OM3-CA] is the first free fatty acid form of long-chain marine omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid being the most abundant) to be approved by the US FDA as an adjunct to diet to lower triglyceride levels in patients with severe hypertriglyceridemia (≥ 500 mg/dL). Oral OM3-CA has greater bioavailability than ethyl ester forms of omega-3 and, unlike omega-3 acid ethyl esters, does not require co-ingestion of a high-fat meal, as it does not need pancreatic enzyme activity for absorption. In the 12-week EpanoVa fOr Lowering Very high triglyceridEs (EVOLVE) trial, OM3-CA 2 or 4 g/day significantly reduced serum triglyceride levels relative to placebo. Other lipid parameters, including non-high-density lipoprotein cholesterol (non-HDL-C), total cholesterol, and very low-density lipoprotein cholesterol (VLDL-C) levels, were also reduced significantly with OM3-CA relative to placebo. Low-density lipoprotein cholesterol levels were increased significantly with OM3-CA relative to placebo; however, these increases were not accompanied by increases in the circulating concentrations of non-HDL-C, VLDL-C, or apolipoprotein B. OM3-CA was generally well tolerated in this study, with most adverse events being of mild or moderate severity. Although additional comparative data are needed to position OM3-CA with respect to other formulations of omega-3 fatty acids, current evidence suggests that OM3-CA is a useful addition to the treatment options available for patients with severe hypertriglyceridemia.

An engineered fatty acid synthase combined with a carboxylic acid reductase enables de novo production of 1-octanol in Saccharomyces cerevisiae.

Science.gov (United States)

Henritzi, Sandra; Fischer, Manuel; Grininger, Martin; Oreb, Mislav; Boles, Eckhard

2018-01-01

The ideal biofuel should not only be a regenerative fuel from renewable feedstocks, but should also be compatible with the existing fuel distribution infrastructure and with normal car engines. As the so-called drop-in biofuel, the fatty alcohol 1-octanol has been described as a valuable substitute for diesel and jet fuels and has already been produced fermentatively from sugars in small amounts with engineered bacteria via reduction of thioesterase-mediated premature release of octanoic acid from fatty acid synthase or via a reversal of the β-oxidation pathway. The previously engineered short-chain acyl-CoA producing yeast Fas1 R1834K /Fas2 fatty acid synthase variant was expressed together with carboxylic acid reductase from Mycobacterium marinum and phosphopantetheinyl transferase Sfp from Bacillus subtilis in a Saccharomyces cerevisiae Δfas1 Δfas2 Δfaa2 mutant strain. With the involvement of endogenous thioesterases, alcohol dehydrogenases, and aldehyde reductases, the synthesized octanoyl-CoA was converted to 1-octanol up to a titer of 26.0 mg L -1 in a 72-h fermentation. The additional accumulation of 90 mg L -1 octanoic acid in the medium indicated a bottleneck in 1-octanol production. When octanoic acid was supplied externally to the yeast cells, it could be efficiently converted to 1-octanol indicating that re-uptake of octanoic acid across the plasma membrane is not limiting. Additional overexpression of aldehyde reductase Ahr from Escherichia coli nearly completely prevented accumulation of octanoic acid and increased 1-octanol titers up to 49.5 mg L -1 . However, in growth tests concentrations even lower than 50.0 mg L -1 turned out to be inhibitory to yeast growth. In situ extraction in a two-phase fermentation with dodecane as second phase did not improve growth, indicating that 1-octanol acts inhibitive before secretion. Furthermore, 1-octanol production was even reduced, which results from extraction of the intermediate octanoic acid to

Enhancing Cooperativity in Bifunctional Acid–Pd Catalysts with Carboxylic Acid-Functionalized Organic Monolayers

Energy Technology Data Exchange (ETDEWEB)

Coan, Patrick D. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Ellis, Lucas D. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Griffin, Michael B. [National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Schwartz, Daniel K. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Medlin, J. Will [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States

2018-03-01

Cooperative catalysts containing a combination of noble metal hydrogenation sites and Bronsted acid sites are critical for many reactions, including the deoxygenation (DO) of biomass-derived oxygenates in the upgrading of pyrolysis oil. One route toward the design of cooperative catalysts is to tether two different catalytically active functions so that they are in close proximity while avoiding undesirable interactions that can block active sites. Here, we deposited carboxylic acid (CA)-functionalized organophosphonate monolayers onto Al2O3-supported Pd nanoparticle catalysts to prepare bifunctional catalysts containing both Bronsted acid and metal sites. Modification with phosphonic acids (PAs) improved activity and selectivity for gas-phase DO reactions, but the degree of improvement was highly sensitive to both the presence and positioning of the CA group, suggesting a significant contribution from both the PA and CA sites. Short spacer lengths of 1-2 methylene groups between the phosphonate head and CA tail were found to yield the best DO rates and selectivities, whereas longer chains performed similarly to self-assembled monolayers having alkyl tails. Results from a combination of density functional theory and Fourier transform infrared spectroscopy suggested that the enhanced catalyst performance on the optimally positioned CAs was due to the generation of strong acid sites on the Al2O3 support adjacent to the metal. Furthermore, the high activity of these sites was found to result from a hydrogen-bonded cyclic structure involving cooperativity between the phosphonate head group and CA tail function. More broadly, these results indicate that functional groups tethered to supports via organic ligands can influence catalytic chemistry on metal nanoparticles.

Determination of tetrahydrophtalimide and 2-thiothiazolidine-4-carboxylic acid, urinary metabolites of the fungicide captan, in rats and humans

NARCIS (Netherlands)

van Welie, R.T.H.; van Duyn, P; Lamme, E K; Jäger, P; van Baar, B L; Vermeulen, N P

1991-01-01

Capillary gas chromatographic (GC) methods using sulphur and mass selective detection for the qualitative and quantitative determination of tetrahydrophtalimide (THPI) and 2-thiothiazolidine-4-carboxylic acid (TTCA), urinary metabolites of the fungicide captan in rat and humans, were developed.

Reaction of uranyl nitrate with carboxylic di-acids under hydrothermal conditions. Crystal structure of complexes with L(+)-tartaric and oxalic acids

International Nuclear Information System (INIS)

Thuery, P.

2007-01-01

L(+)-tartaric acid reacts with uranyl nitrate in the presence of KOH, under mild hydrothermal conditions, to give the complex [UO 2 (C 4 H 4 O 6 )(H 2 O)] (1), the first uranyl tartrate to be crystallographically characterized. Each tartrate ligand bridges three uranyl ions, one of them in chelating fashion through proximal carboxylate and hydroxyl groups. The resulting assemblage is two-dimensional, with the uranyl pentagonal bipyramidal coordination polyhedra separated from one another. Prolonged heating of an uranyl tartrate solution resulted in oxidative cleavage of the acid and formation of the oxalate complex [(UO 2 ) 2 (C 2 O 4 ) 2 (OH)Na(H 2 O) 2 ] (2). The bis-bidentate oxalate and bridging hydroxide groups ensure the formation of sheets with corner-sharing uranyl pentagonal bipyramidal coordination polyhedra, in which six-membered metallacycles encompass the sodium ions. These sheets are assembled into a three-dimensional framework through further oxo-bonding of the sodium ions. (authors)

A relativistic density functional study of uranyl hydrolysis and complexation by carboxylic acids in aqueous solution

International Nuclear Information System (INIS)

Ray, Rupashree Shyama

2009-01-01

In this work, the complexation of uranium in its most stable oxidation state VI in aqueous solution was studied computationally, within the framework of density functional (DF) theory. The thesis is divided into the following parts: Chapter 2 briefly summarizes the relevant general aspects of actinide chemistry and then focuses on actinide environmental chemistry. Experimental results on hydrolysis, actinide complexation by carboxylic acids, and humic substances are presented to establish a background for the subsequent discussion. Chapter 3 describes the computational method used in this work and the relevant features of the parallel quantum chemistry code PARAGAUSS employed. First, the most relevant basics of the applied density functional approach are presented focusing on relativistic effects. Then, the treatment of solvent effects, essential for an adequate modeling of actinide species in aqueous solution, will be introduced. At the end of this chapter, computational parameters and procedures will be summarized. Chapter 4 presents the computational results including a comparison to available experimental data. In the beginning, the mononuclear hydrolysis product of UO_2"2"+, [UO_2OH]"+, will be discussed. The second part deals with actinide complexation by carboxylate ligands. First of all the coordination number for uranylacetate will be discussed with respect to implications for the complexation of actinides by humic substances followed by the uranyl complexation of aromatic carboxylic acids in comparison to earlier results for aliphatic ones. In the end, the ternary uranyl-hydroxo-acetate are discussed, as models of uranyl humate complexation at ambient condition.

Effect of carboxylic acid of periodic mesoporous organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems

Energy Technology Data Exchange (ETDEWEB)

Dutta, Saikat; Wu, Kevin C.-W., E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Kao, Hsien-Ming, E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw [Department of Chemistry, National Central University, Chung-Li 32054, Taiwan (China)

2014-11-01

This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (–COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and {sup 13}C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed.

Effect of carboxylic acid of periodic mesoporous organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems

International Nuclear Information System (INIS)

Dutta, Saikat; Wu, Kevin C.-W.; Kao, Hsien-Ming

2014-01-01

This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (–COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and 13 C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed

Effect of a Long Chain Carboxylate Acid on Sodium Dodecyl Sulfate Micelle Structure: A Small-angle Neutron Scattering Study

International Nuclear Information System (INIS)

Arum Patriati; Edy Giri Rachman Putra

2009-01-01

The effect of different hydrocarbon chain length of carboxylate acid, i.e. dodecanoic acid, CH 3 (CH 2 ) 10 COOH and hexadecanoic acid, CH 3 (CH 2 ) 14 COOH as a co-surfactant in the 0.3M SDS micellar solution has been studied using small angle neutron scattering (SANS). Here, the present of dodecanoic acid has induced the SDS structural micelles. The ellipsoid micelles structures changed significantly in length (major axis) from 21.7 Armstrong to 35.5 Armstrong at a fixed minor axis of 16.7 Armstrong in the present of 0.005M to 0.1M dodecanoic acid. Nevertheless, this effect was not shown in the present of hexadecanoic acid with the same concentration range. The present of hexadecanoic acid molecules gave a small effect on growth of SDS micelles where the major axis of the micelle was simply elongated from 21.5 Armstrong to 23.5 Armstrong. It showed that the appropriate hydrocarbon chain length between surfactant and co-surfactant molecules is one of the determining factors in forming a mixed micelles structure. (author)

Dynamically formed hydrous zirconium (IV) oxide-polyelectrolyte membranes. III: Poly(acrylic acid) and substituted poly(acrylic acid) homo, co and terpolymer membranes

International Nuclear Information System (INIS)

Van Reenen, A.J.; Sanderson, R.D.

1989-01-01

A series of acrylic acid and substituted acrylic acid homo, co and terpolymers was synthesised. These polymers were used as polyelectrolytes in dynamically formed hydrous zirconium (iv) oxide-polyelectrolyte membranes. Substitution of the acrylic acid α-hydrogen was done to increase the number of carboxylic acid groups per monomer unit and to change the acid strength of acrylic acid carboxylic acid group. None of these changes improved the salt rejection of these membranes over that of commercially used poly(acrylic acid). Improvement in rejection was found when a hydrophobic comonomer, vinyl acetate, was used in conjunction with acrylic acid in a copolymer dynamic membrane. 16 refs., 6 figs., 1 tab

Palladium-Catalyzed Decarboxylative γ-Olefination of 2,5-Cyclohexadiene-1-carboxylic Acid Derivatives with Vinyl Halides.

Science.gov (United States)

Chang, Chi-Hao; Chou, Chih-Ming

2018-04-06

This study explores a Pd-catalyzed decarboxylative Heck-type Csp 3 -Csp 2 coupling reaction of 2,5-cyclohexadiene-1-carboxylic acid derivatives with vinyl halides to provide γ-olefination products. The olefinated 1,3-cyclohexadienes can be further oxidized to produce meta-alkylated stilbene derivatives. Additionally, the conjugated diene products can also undergo a Diels-Alder reaction to produce a bicyclo[2.2.2]octadiene framework.

Chemistry and electrochemistry in trifluoroacetic acid. Comparison with acetic acid

International Nuclear Information System (INIS)

Petit, Gerard

1972-01-01

As the trifluoroacetic acid is, with the acetic acid, one of most often used carboxylic acids as solvent, notably in organic chemistry, this research thesis addresses some relatively simple complexing and redox reactions to highlight the peculiar feature of this acid, and to explain its very much different behaviour with respect to acetic acid. The author develops the notion of acidity level in solvents of low dielectric constant. The second part addresses a specific solvent: BF 3 (CH 3 COOH) 2 . The boron trifluoride strengthens the acidity of acetic acid and modifies its chemical and physical-chemical properties. In the third part, the author compares solvent properties of CF 3 COOH and CH 3 COOH. Noticed differences explain why the trifluoroacetic acid is a more interesting reaction environment than acetic acid for reactions such as electrophilic substitutions or protein solubilisation [fr

Proton-conducting membranes based on benzimidazole-containing sulfonated poly(ether ether ketone) compared with their carboxyl acid form

Energy Technology Data Exchange (ETDEWEB)

Li, Hongtao; Wu, Jing; Zhao, Chengji; Zhang, Gang; Zhang, Yang; Shao, Ke; Xu, Dan; Lin, Haidan; Han, Miaomiao; Na, Hui [Alan G MacDiarmid Institute, College of Chemistry, Jilin University, Changchun 130012 (China)

2009-10-15

A series of sulfonated poly(ether ether ketone) containing pendant carboxyl (C-SPEEKs) have been synthesized using a nucleophilic polycondesation reaction. A condensation reaction between 1,2-diaminobenzene and carboxyl resulted in a new series of copolymers containing benzimidazole groups (SPEEK-BIms). The expected structures of the sulfonated copolymers are confirmed by {sup 1}H NMR. The dependence of ion exchange capacity, water uptake, proton conductivity and methanol diffusion coefficient of SPEEK-BIm membranes has been studied and compared with their carboxyl acid form. The results suggest that the introduction of benzimidazole groups may be responsible for many excellent properties of the membranes for fuel cell. It is noticeable that the markedly improved oxidative stability is benefit for the application of membrane. (author)

Rhodium-catalyzed regioselective olefination directed by a carboxylic group.

Science.gov (United States)

Mochida, Satoshi; Hirano, Koji; Satoh, Tetsuya; Miura, Masahiro

2011-05-06

The ortho-olefination of benzoic acids can be achieved effectively through rhodium-catalyzed oxidative coupling with alkenes. The carboxylic group is readily removable to allow ortho-olefination/decarboxylation in one pot. α,β-Unsaturated carboxylic acids such as methacrylic acid also undergo the olefination at the β-position. Under the rhodium catalysis, the cine-olefination of heteroarene carboxylic acids such as thiophene-2-carboxylic acid proceeds smoothly accompanied by decarboxylation to selectively produce the corresponding vinylheteroarene derivatives. © 2011 American Chemical Society

Electrocatalytic carboxylation of chloroacetonitrile at a silver cathode for the synthesis of cyanoacetic acid

Energy Technology Data Exchange (ETDEWEB)

Scialdone, Onofrio [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)], E-mail: scialdone@dicpm.unipa.it; Galia, Alessandro; Filardo, Giuseppe [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Isse, Abdirisak Ahmed [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, 35131 Padova (Italy)], E-mail: Abdirisak.ahmedisse@unipd.it; Gennaro, Armando [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, 35131 Padova (Italy)

2008-12-30

The electrocatalytic carboxylation of chloroacetonitrile to cyanoacetic acid performed at silver cathodes was investigated both theoretically and experimentally. Silver exhibits powerful electrocatalytic activities towards the reduction of chloroacetonitrile. In CO{sub 2}-saturated CH{sub 3}CN, reduction of NCCH{sub 2}Cl occurs at potentials that are about 0.7 V more positive than those observed at glassy carbon and gives cyanoacetic acid in good yields. Theoretical considerations on the effect of operative parameters on the performances of the process were confirmed by electrocarboxylation experiments performed in undivided cells equipped with sacrificial anodes both in a bench-scale electrochemical batch reactor and in a continuous batch recirculation reaction system equipped with a parallel plate electrochemical cell. Selectivities and Faradic efficiencies higher than 80% were obtained by working under anhydrous conditions both under amperostatic and potentiostatic alimentation at proper values of either current density or applied potential.

4-Methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylic Acid. Peculiarities of Preparation, Structure, and Biological Properties

Directory of Open Access Journals (Sweden)

Igor V. Ukrainets

2018-03-01

Full Text Available In order to determine the regularities of the structure–analgesic activity relationship, the peculiarities of obtaining, the spatial structure, and biological properties of 4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylic acid and some of its derivatives have been studied. Using nuclear magnetic resonance (NMR spectroscopy and X-ray diffraction analysis, it has been proven that varying the reaction conditions using alkaline hydrolysis of methyl 4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylate makes it possible to successfully synthesize a monohydrate of the target acid, its sodium salt, or 4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine. The derivatographic study of the thermal stability of 4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylic acid monohydrate has been carried out; based on this study, the optimal conditions completely eliminating the possibility of unwanted decomposition have been proposed for obtaining its anhydrous form. It has been shown that 4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine is easily formed during the decarboxylation of not only 4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylic acid, but also its sodium salt, which is capable of losing СО2 both in rather soft conditions of boiling in an aqueous solution, and in more rigid conditions of dry heating. The NMR spectra of the compounds synthesized are given; their spatial structure is discussed. To study the biological properties of 4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylic acid and its sodium salt, the experimental model of inflammation caused by subplantar introduction of the carrageenan solution in one of the hind limbs of white rats was used. The anti-inflammatory activity and analgesic effect were assessed by the degree of edema reduction and the ability to affect the pain response compared to the animals of control groups. According to the results of the tests performed, it has been found that after intraperitoneal injection

Catalytic transformation of functionalized carboxylic acids using multifunctional rhenium complexes.

Science.gov (United States)

Naruto, Masayuki; Agrawal, Santosh; Toda, Katsuaki; Saito, Susumu

2017-06-13

Carboxylic acids (CAs) are one of the most ubiquitous and important chemical feedstocks available from biorenewable resources, CO 2 , and the petrochemical industry. Unfortunately, chemoselective catalytic transformations of CH n CO 2 H (n = 1-3) groups into other functionalities remain a significant challenge. Herein, we report rhenium V complexes as extremely effective precatalysts for this purpose. Compared to previously reported heterogeneous and homogeneous catalysts derived from high- or low-valent metals, the present method involves a α-C-H bond functionalization, a hydrogenation, and a hydrogenolysis, which affords functionalized alcohols with a wide substrate scope and high chemoselectivity under relatively mild reaction conditions. The results represent an important step toward a paradigm shift from 'low-valent' to 'high-valent' metal complexes by exploring a new portfolio of selective functional group transformations of highly oxygenated organic substrates, as well as toward the exploitation of CAs as a valuable biorenewable feedstock.

A relativistic density functional study of uranyl hydrolysis and complexation by carboxylic acids in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Ray, Rupashree Shyama

2009-02-10

In this work, the complexation of uranium in its most stable oxidation state VI in aqueous solution was studied computationally, within the framework of density functional (DF) theory. The thesis is divided into the following parts: Chapter 2 briefly summarizes the relevant general aspects of actinide chemistry and then focuses on actinide environmental chemistry. Experimental results on hydrolysis, actinide complexation by carboxylic acids, and humic substances are presented to establish a background for the subsequent discussion. Chapter 3 describes the computational method used in this work and the relevant features of the parallel quantum chemistry code PARAGAUSS employed. First, the most relevant basics of the applied density functional approach are presented focusing on relativistic effects. Then, the treatment of solvent effects, essential for an adequate modeling of actinide species in aqueous solution, will be introduced. At the end of this chapter, computational parameters and procedures will be summarized. Chapter 4 presents the computational results including a comparison to available experimental data. In the beginning, the mononuclear hydrolysis product of UO{sub 2}{sup 2+}, [UO{sub 2}OH]{sup +}, will be discussed. The second part deals with actinide complexation by carboxylate ligands. First of all the coordination number for uranylacetate will be discussed with respect to implications for the complexation of actinides by humic substances followed by the uranyl complexation of aromatic carboxylic acids in comparison to earlier results for aliphatic ones. In the end, the ternary uranyl-hydroxo-acetate are discussed, as models of uranyl humate complexation at ambient condition.

Erbium trifluoromethanesulfonate-catalyzed Friedel–Crafts acylation using aromatic carboxylic acids as acylating agents under monomode-microwave irradiation

DEFF Research Database (Denmark)

Tran, Phuong Hoang; Hansen, Poul Erik; Nguyen, Hai Truong

2015-01-01

Erbium trifluoromethanesulfonate is found to be a good catalyst for the Friedel–Crafts acylation of arenes containing electron-donating substituents using aromatic carboxylic acids as the acylating agents under microwave irradiation. An effective, rapid and waste-free method allows the preparation...... of a wide range of aryl ketones in good yields and in short reaction times with minimum amounts of waste...

Sodium borohydride reduction of aromatic carboxylic acids via ...

Indian Academy of Sciences (India)

Unknown

using a sodium borohydride–THF–methanol system. The alcohols ... rature using ethanol or methanol as solvent. Although, .... acids, phenylacetic acids, phenylpropanoic acid and cinnamic ... excess of reagent in water or alcohol, involved a.

Triboelectrification of active pharmaceutical ingredients: week acids and their salts.

Science.gov (United States)

Fujinuma, Kenta; Ishii, Yuji; Yashihashi, Yasuo; Yonemochi, Estuo; Sugano, Kiyohiko; Tarada, Katsuhide

2015-09-30

The effect of salt formulation on the electrostatic property of active pharmaceutical ingredients was investigated. The electrostatic property of weak acids (carboxylic acids and amide-enole type acid) and their sodium salts was evaluated by a suction-type Faraday cage meter. Free carboxylic acids showed negative chargeability, whereas their sodium salts showed more positive chargeability than the free acids. However, no such trend was observed for amide-enole type acids. Copyright © 2015 Elsevier B.V. All rights reserved.

Luminescent hybrid lanthanide sulfates and lanthanide sulfonate-carboxylates with 1,10-phenanthroline involving in-situ oxidation of 2-mercaptonbenzoic acid

Science.gov (United States)

Zhong, Jie-Cen; Wan, Fang; Sun, Yan-Qiong; Chen, Yi-Ping

2015-01-01

A series of lanthanide sulfates and lanthanide sulfonate-carboxylates, [Ln2(phen)2(SO4)3(H2O)2]n (I:Ln=Nd(1a), Sm(1b), Eu(1c), phen=1,10-phenanthroline) and [Ln(phen)(2-SBA)(BZA)]n (II: Ln=Sm(2a), Eu(2b), Dy(2c), 2-SBA=2-sulfobenzoate, BZA=benzoate) have been hydrothermally synthesized from lanthanide oxide, 2-mercaptonbenzoic acid with phen as auxiliary ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, TG analyses and luminescence spectroscopy. Interestingly, SO4 2 - anions in I came from the in situ deep oxidation of thiol groups of 2-mercaptonbenzoic acid while 2-sulfobenzoate and benzoate ligands in II from the middle oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. Compounds I are organic-inorganic hybrid lanthanide sulfates, which have rare one-dimensional column-like structures. Complexes II are binuclear lanthanide sulfonate-carboxylates with 2-sulfobenzoate and benzoate as bridges and 1,10-phenanthroline as terminal. Photoluminescence studies reveal that complexes I and II exhibit strong lanthanide characteristic emission bands in the solid state at room temperature.

Acid-functionalized polyolefin materials and their use in acid-promoted chemical reactions

Science.gov (United States)

Oyola, Yatsandra; Tian, Chengcheng; Bauer, John Christopher; Dai, Sheng

2016-06-07

An acid-functionalized polyolefin material that can be used as an acid catalyst in a wide range of acid-promoted chemical reactions, wherein the acid-functionalized polyolefin material includes a polyolefin backbone on which acid groups are appended. Also described is a method for the preparation of the acid catalyst in which a precursor polyolefin is subjected to ionizing radiation (e.g., electron beam irradiation) of sufficient power and the irradiated precursor polyolefin reacted with at least one vinyl monomer having an acid group thereon. Further described is a method for conducting an acid-promoted chemical reaction, wherein an acid-reactive organic precursor is contacted in liquid form with a solid heterogeneous acid catalyst comprising a polyolefin backbone of at least 1 micron in one dimension and having carboxylic acid groups and either sulfonic acid or phosphoric acid groups appended thereto.

Biomedical applications of SPION@APTES@PEG-folic acid@carboxylated quercetin nanodrug on various cancer cells

International Nuclear Information System (INIS)

Akal, Z.Ü.; Alpsoy, L.; Baykal, A.

2016-01-01

Highlights: • SPION has been synthesized via Reflux synthesis route. • SPION@APTES@FA-PEG@CQ nanodrug has super paramagnetic property. • SPION@APTES@FA-PEG@CQ nanodrug has cytotoxic, apoptotic and necrotic effects on HeLa and MCF-7 cells. • SPION@APTES@FA-PEG@CQ nanodrug can be potentially used for the delivery of quercetin to cervical and breast cancer cells. - Abstract: In this study, carboxylated quercetin (CQ) was conjugated to superparamagnetic iron oxide nanoparticles (SPIONs) which were modified by (3-aminopropyl) triethoxysilane (APTES), Folic acid (FA) and carboxylated Polyethylene glycol (PEG); (SPION@APTES@FA-PEG@CQ), nanodrug has been synthesized via polyol and accompanying by various chemical synthesis routes. The characterization of the final product was done via X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), Transmission electron spectroscopy (TEM) and Vibrating sample magnetometer (VSM). Its cytotoxic and apoptotic activities on over expressed folic acid receptor (FR + ) (MCF-7, HeLa) and none expressed folic acid receptor (FR-) (A549) cancer cell lines were determined by using MTT assay, Real-Time Cell Analysis, TUNEL assay, Annexin assay and RT-PCR analysis for Caspase3/7 respectively. SPION@APTES@FA-PEG@CQ nanodrug showed higher cytotoxicity against HeLa and MCF-7 cell lines as compared with A549 cell line. Moreover, SPION@APTES@FA-PEG@CQ nanodrug also caused higher apoptotic and necrotic effects in 100 μg/mL HeLa and MCF-7 cells than A549 cells. The findings showed that SPION@APTES@FA-PEG@CQ nanodrug has cytotoxic, apoptotic and necrotic effects on HeLa and MCF-7 which are FR over expressed cell lines and can be potentially used for the delivery of quercetin to cervical and breast cancer cells.

Biomedical applications of SPION@APTES@PEG-folic acid@carboxylated quercetin nanodrug on various cancer cells

Energy Technology Data Exchange (ETDEWEB)

Akal, Z.Ü., E-mail: zulker@fatih.edu.tr [Department of Biology, 34500 Büyükçekmece, Istanbul (Turkey); Alpsoy, L. [Department of Biology, 34500 Büyükçekmece, Istanbul (Turkey); Department of Medical Biology, 34500 Büyükçekmece, Istanbul (Turkey); Baykal, A. [Department of Chemistry, Fatih University, 34500 Büyükçekmece, Istanbul (Turkey)

2016-08-15

Highlights: • SPION has been synthesized via Reflux synthesis route. • SPION@APTES@FA-PEG@CQ nanodrug has super paramagnetic property. • SPION@APTES@FA-PEG@CQ nanodrug has cytotoxic, apoptotic and necrotic effects on HeLa and MCF-7 cells. • SPION@APTES@FA-PEG@CQ nanodrug can be potentially used for the delivery of quercetin to cervical and breast cancer cells. - Abstract: In this study, carboxylated quercetin (CQ) was conjugated to superparamagnetic iron oxide nanoparticles (SPIONs) which were modified by (3-aminopropyl) triethoxysilane (APTES), Folic acid (FA) and carboxylated Polyethylene glycol (PEG); (SPION@APTES@FA-PEG@CQ), nanodrug has been synthesized via polyol and accompanying by various chemical synthesis routes. The characterization of the final product was done via X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), Transmission electron spectroscopy (TEM) and Vibrating sample magnetometer (VSM). Its cytotoxic and apoptotic activities on over expressed folic acid receptor (FR + ) (MCF-7, HeLa) and none expressed folic acid receptor (FR-) (A549) cancer cell lines were determined by using MTT assay, Real-Time Cell Analysis, TUNEL assay, Annexin assay and RT-PCR analysis for Caspase3/7 respectively. SPION@APTES@FA-PEG@CQ nanodrug showed higher cytotoxicity against HeLa and MCF-7 cell lines as compared with A549 cell line. Moreover, SPION@APTES@FA-PEG@CQ nanodrug also caused higher apoptotic and necrotic effects in 100 μg/mL HeLa and MCF-7 cells than A549 cells. The findings showed that SPION@APTES@FA-PEG@CQ nanodrug has cytotoxic, apoptotic and necrotic effects on HeLa and MCF-7 which are FR over expressed cell lines and can be potentially used for the delivery of quercetin to cervical and breast cancer cells.

STUDY OF ORGANIC ACIDS IN ALMOND LEAVES

Directory of Open Access Journals (Sweden)

Lenchyk L.V.

2015-05-01

Full Text Available Introduction. Almond (Amygdalus communis is a stone fruit, from the Rosaceae family, closest to the peach. It is spread throughout the entire Mediterranean region and afterwards to the Southwestern USA, Northern Africa, Turkey, Iran, Australia and South Africa. It is sensitive to wet conditions, and therefore is not grown in wet climates. Iran is located in the semi-arid region of the world. Because of its special tolerance to water stress, almond is one of the main agricultural products in rainfed condition in Iran. Almond leaves have been investigated for their phenolic content and antioxidant activity. It was found that total antioxidant activity and phenolic compounds exhibited variations according to season, plant organ (leaf and stem and variety. Analysis of previous research on almonds focused on investigating compounds mostly in seeds and phenolic compounds in leaves, but organic acids in leaves have not been studied. Aim of this study was investigation of organic acids in leaves of almond variety which is distributed in Razavi Khorasan province of Iran. Materials and Methods. In August 2012 almond leaves were collected in Iran, dried and grinded. The study of qualitative composition and quantitative determination of carboxylic acids in almond leaves was carried out by gas chromatography with mass spectrometric detection. For determination organic acids content, to 50 mg of dried plant material in 2 ml vial internal standard (50 μg of tridecane in hexane was added and filled up with 1.0 ml of methylating agent (14 % BCl3 in methanol, Supelco 3-3033. The mixture was kept in a sealed vial during 8 hours at 65 °C. At this time fatty oil was fully extracted, and hydrolyzed into its constituent fatty acids and their methylation was done. At the same time free organic and phenolcarbonic acids were methylated too. The reaction mixture was poured from the plant material sediment and was diluted with 1 ml of distilled water. To extract methyl

21 CFR 186.1316 - Formic acid.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Formic acid. 186.1316 Section 186.1316 Food and... Substances Affirmed as GRAS § 186.1316 Formic acid. (a) Formic acid (CH2O2, CAS Reg. No. 64-18-6) is also referred to as methanoic acid or hydrogen carboxylic acid. It occurs naturally in some insects and is...

A structural and functional model for the 1-aminocyclopropane-1-carboxylic acid oxidase.

Science.gov (United States)

Sallmann, Madleen; Oldenburg, Fabio; Braun, Beatrice; Réglier, Marius; Simaan, A Jalila; Limberg, Christian

2015-10-12

The hitherto most realistic low-molecular-weight analogue for the 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO) is reported. The ACCOs 2-His-1-carboxylate iron(II) active site was mimicked by a TpFe moiety, to which the natural substrate ACC could be bound. The resulting complex [Tp(Me,Ph) FeACC] (1), according to X-ray diffraction analysis performed for the nickel analogue, represents an excellent structural model, featuring ACC coordinated in a bidentate fashion-as proposed for the enzymatic substrate complex-as well as a vacant coordination site that forms the basis for the first successful replication also of the ACCO function: 1 is the first known ACC complex that reacts with O2 to produce ethylene. As a FeOOH species had been suggested as intermediate in the catalytic cycle, H2 O2 was tested as the oxidant, too, and indeed evolution of ethylene proceeded even more rapidly to give 65 % yield. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural and thermodynamic study of rare earth(III) complexation by poly-hydroxylated carboxylic acids: synthesis of new extractants and outlook for the extraction of these cations

International Nuclear Information System (INIS)

Aury, S.

2002-12-01

The aim of this work is: to improve the knowledge on the binding sites of the poly-hydroxylated carboxylic acids with the trivalent lanthanide(III) ions by comparing them to gluconic acid (previously studied) and to molecules with different configuration and with a variable number of OH functions (threonic acid, glyceric acid, 2-hydroxy-butanoic acid, 3-hydroxy-butanoic acid). To find the best complexing agent among different acids (aldonic acids, aldaric acids, di-hydroxybenzoic acids) (determination of the set of complexes and their stability constants by potentiometry, NMR and UV-Visible spectroscopy). To synthesize hydrophobic monoamides from one lactone form of saccharic acid, to study their complexing power and their capacity to extract the trivalent lanthanide(III) ions. (author)

Tropanol esters of metallocene carboxylic acids. Syntheses, labelling with 103Ru and sup(103m)Rh and organ distribution

International Nuclear Information System (INIS)

Wenzel, M.; Wu, Y.

1988-01-01

The tropanol esters of the carboxylic acids of ferrocene, 103 Ru-ruthenocene and sup(103m)Rh-rhodocinium were synthezised. The organ distribution of the 103 Ru or sup(103m)Rh labelled tropanol-esters were investigated. Only the 103 Ru labelled ester showed a high heart/blood ratio. (author)

Amino acid analogs for tumor imaging

International Nuclear Information System (INIS)

Goodman, M.M.; Shoup, T.

1998-01-01

The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is [ 18 F]-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an α-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of α-aminoisobutyric acid

[Pollution characteristics of organic acids in atmospheric particles during haze periods in autumn in Guangzhou].

Science.gov (United States)

Tan, Ji-hua; Zhao, Jing-ping; Duan, Jing-chun; Ma, Yong-liang; He, Ke-bin; Yang, Fu-mo

2013-05-01

Total suspended particles (TSP), collected during a typical haze period in Guangzhou, were analyzed for the fatty acids (C12-C30) and low molecular weight dicarboxylic acids (C3-C9) using gas chromatography/mass spectrometry (GC/MS). The results showed that the concentration of total fatty and carboxylic acids was pretty high during the haze episode. The ratios of fatty acids and carboxylic acids in haze to those in normal days were 1.9 and 2.5, respectively. During the episode of the increasing pollution, the fatty acids and carboxylic acids at night (653 ng x m(-3)) was higher than that (487 ng x m(-3)) in days. After that, the level of fatty acids and carboxylic acids in days (412 ng x m(-3)) was higher than that (336 ng x m(-3)) at night. In general, the time-series of fatty acids and carboxylic acids was similar to that of the air particle and carbonaceous species, however, the trend of the ratio of fatty acids and carboxylic acids to organic carbon was opposite to that of air particle and carbonaceous species. This ratio decreased with the increase of the concentration of air particle and after the night of 27th, the ratio increased with the decrease in the concentration of air particle. The results showed that haze pollution had a significant inhibitory effect on the enrichment of fatty and carboxylic acids. Based on the ratio of malonate to succinate (C3/C4), it could be found that primary sources contribute more to the atmospheric fatty and carboxylic acids during the autumn haze pollution periods in Guangzhou.

Photoacidic and Photobasic Behavior of Transition Metal Compounds with Carboxylic Acid Group(s)

Energy Technology Data Exchange (ETDEWEB)

O’Donnell, Ryan M. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Sampaio, Renato N. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Li, Guocan [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Johansson, Patrik G. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Ward, Cassandra L. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Meyer, Gerald J. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States

2016-03-10

Excited state proton transfer studies of six Ru polypyridyl compounds with carboxylic acid/carboxylate group(s) revealed that some were photoacids and some were photobases. The compounds [Ru^II(btfmb)₂(LL)]²⁺, [Ru^II(dtb)2(LL)]2+, and [RuII(bpy)2(LL)]2+, where bpy is 2,2'-bipyridine, btfmb is 4,4'-(CF₃)₂-bpy, and dtb is 4,4'-((CH₃)₃C)₂-bpy, and LL is either dcb = 4,4'-(CO₂H)₂-bpy or mcb = 4-(CO₂H),4'-(CO2Et)-2,2'-bpy, were synthesized and characterized. The compounds exhibited intense metal-to-ligand charge-transfer (MLCT) absorption bands in the visible region and room temperature photoluminescence (PL) with long τ > 100 ns excited state lifetimes. The mcb compounds had very similar ground state pKa’s of 2.31 ± 0.07, and their characterization enabled accurate determination of the two pK_a values for the commonly utilized dcb ligand, pK_a1 = 2.1 ± 0.1 and pKa2 = 3.0 ± 0.2. Compounds with the btfmb ligand were photoacidic, and the other compounds were photobasic. Transient absorption spectra indicated that btfmb compounds displayed a [Ru^III(btfmb–)L₂]^2+* localized excited state and a [Ru^III(dcb–)L₂]^2+* formulation for all the other excited states. Time dependent PL spectral shifts provided the first kinetic data for excited state proton transfer in a transition metal compound. PL titrations, thermochemical cycles, and kinetic analysis (for the mcb compounds) provided self-consistent pK_a* values. The ability to make a single ionizable group photobasic or photoacidic through ligand design was unprecedented and was understood based on the orientation of the lowest-lying MLCT excited state dipole relative to the ligand that contained the carboxylic acid group(s).

What is the enthalpy of formation of pyrazine-2-carboxylic acid?

International Nuclear Information System (INIS)

Miranda, Margarida S.; Duarte, Darío J.R.; Liebman, Joel F.

2016-01-01

There are two contemporary conflicting, indeed, incompatible determinations of measurements of the enthalpies of combustion and of formation of pyrazine-2-carboxylic acid in the literature, (−2268.0 ± 0.9 and −271.2 ± 1.1 kJ · mol −1 ) and (−2211.4 ± 0.9 and −327.8 ± 1.1 kJ · mol −1 ). The current paper discusses these two sets of values and from the use of a measurement of the enthalpy of sublimation, a newly evaluated enthalpy of formation of pyrazine itself, and of the quantum chemical calculations at the G3(MP2)//B3LYP level, the former results are accepted and the derived gas phase enthalpy of formation, −(167.6 ± 3.1) kJ · mol −1 , suggested.

Liquid chromatographic determination of urinary 2-thiothiazolidine-4-carboxylic acid, a biomarker of carbon disulphide exposure.

Science.gov (United States)

Lee, B L; Yang, X F; New, A L; Ong, C N

1995-06-23

An effective gradient high-performance liquid chromatographic method for baseline separation of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA), with photodiode array detection at 271 nm was described. o-Methylhippuric acid was used as an internal standard (I.S.). A 1-ml urine sample was saturated with 300 mg of sodium sulphate, acidified with 100 microliters of 6 M hydrochloric acid, extracted twice with 2 ml of diethyl ether, and after evaporation, the residue was taken up in 1 ml of 0.1% (v/v) phosphoric acid. The two mobile phases used for gradient elution were: (A) 10 mM ammonium dihydrogenphosphate (pH 3.5) and (B) same concentration of buffer but containing 20% (v/v) of methanol (pH 4.8). The flow-rate was set at 1.0 ml/min. TTCA and I.S. were detected at 2.2 and 9.1 min, respectively. The method was validated with urine samples collected from normal subjects and workers occupationally exposed to carbon disulphide. The present method enables the detection of urinary TTCA at a concentration of 0.025 mg/l. Analytical recovery and reproducibility generally exceeded 90%. The proposed method is considered more sensitive, specific and reliable than other existing methods.

Prediction of protein modification sites of pyrrolidone carboxylic acid using mRMR feature selection and analysis.

Directory of Open Access Journals (Sweden)

Lu-Lu Zheng

Full Text Available Pyrrolidone carboxylic acid (PCA is formed during a common post-translational modification (PTM of extracellular and multi-pass membrane proteins. In this study, we developed a new predictor to predict the modification sites of PCA based on maximum relevance minimum redundancy (mRMR and incremental feature selection (IFS. We incorporated 727 features that belonged to 7 kinds of protein properties to predict the modification sites, including sequence conservation, residual disorder, amino acid factor, secondary structure and solvent accessibility, gain/loss of amino acid during evolution, propensity of amino acid to be conserved at protein-protein interface and protein surface, and deviation of side chain carbon atom number. Among these 727 features, 244 features were selected by mRMR and IFS as the optimized features for the prediction, with which the prediction model achieved a maximum of MCC of 0.7812. Feature analysis showed that all feature types contributed to the modification process. Further site-specific feature analysis showed that the features derived from PCA's surrounding sites contributed more to the determination of PCA sites than other sites. The detailed feature analysis in this paper might provide important clues for understanding the mechanism of the PCA formation and guide relevant experimental validations.

Conjugates of 1'-Aminoferrocene-1-carboxylic Acid and Proline: Synthesis, Conformational Analysis and Biological Evaluation

Directory of Open Access Journals (Sweden)

Monika Kovačević

2014-08-01

Full Text Available Our previous studies showed that alteration of dipeptides Y-Fca-Ala-OMe (III into Y-Ala-Fca-OMe (IV (Y = Ac, Boc; Fca = 1'-aminoferrocene-1-carboxylic acid significantly influenced their conformational space. The novel bioconjugates Y-Fca-Pro-OMe (1, Y = Ac; 2, Y = Boc and Y-Pro-Fca-OMe (3, Y = Boc; 4, Y = Ac have been prepared in order to investigate the influence of proline, a well-known turn-inducer, on the conformational properties of small organometallic peptides with an exchanged constituent amino acid sequences. For this purpose, peptides 1–4 were subjected to detailed spectroscopic analysis (IR, NMR, CD spectroscopy in solution. The conformation of peptide 3 in the solid state was determined. Furthermore, the ability of the prepared conjugates to inhibit the growth of estrogen receptor-responsive MCF-7 mammary carcinoma cells and HeLa cervical carcinoma cells was tested.

Synthesis and Structural Characterization of 1- and 2-Substituted Indazoles: Ester and Carboxylic Acid Derivatives

Directory of Open Access Journals (Sweden)

Isabel Bento

2006-11-01

Full Text Available A series of indazoles substituted at the N-1 and N-2 positions with ester-containing side chains -(CH2nCO2R of different lengths (n = 0-6, 9, 10 are described.Nucleophilic substitution reactions on halo esters (X(CH2nCO2R by 1H-indazole inalkaline solution lead to mixtures of N-1 and N-2 isomers, in which the N-1 isomerpredominates. Basic hydrolysis of the ester derivatives allowed the synthesis of thecorresponding indazole carboxylic acids. All compounds were fully characterised bymultinuclear NMR and IR spectroscopies, MS spectrometry and elemental analysis; theNMR spectroscopic data were used for structural assignment of the N-1 and N-2 isomers.The molecular structure of indazol-2-yl-acetic acid (5b was determined by X-raydiffraction, which shows a supramolecular architecture involving O2-H...N1intermolecular hydrogen bonds.

In situ SERS and X-ray photoelectron spectroscopy studies on the pH-dependant adsorption of anthraquinone-2-carboxylic acid on silver electrode

Energy Technology Data Exchange (ETDEWEB)

Li, Dan, E-mail: dany@sit.edu.cn [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Jia, Shaojie [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Fodjo, Essy Kouadio [Laboratory of Physical Chemistry, University Felix Houphouet Boigny, 22 BP 582, Abidjan 22, Cote d’Ivoire (Cote d' Ivoire); Xu, Hu [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Wang, Yuhong, E-mail: yuhong_wang502@sit.edu.cn [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Deng, Wei [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China)

2016-03-30

Graphical abstract: The orientation of anthraquinone-2-carboxylic acid (AQ-2-COOH) has been investigated by in situ surface-enhanced Raman scattering (in situ SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) on silver surface. - Highlights: • The adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on Ag electrode is influenced by the pH. • The pH-dependant adsorption of AQ-2-COOH has been confirmed by in situ surface-enhanced Raman scattering (in situ SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS). • The results can provide insights into electron transfer reactions of AQ-2-COOH in biological systems. - Abstract: In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from −0.3 to −0.5 V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from −0.3 to −0.5 V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented.

Development of starch biofilms using different carboxylic acids as plasticizers; Desenvolvimento de biofilmes de amido utilizando como plastificantes diferentes acidos carboxilicos

Energy Technology Data Exchange (ETDEWEB)

Cruz, L.C.; Miranda, C.S.; Santos, W.J. dos; Goncalves, A.P.B.; Oliveira, J.C.; Jose, N.M., E-mail: uanaconceicaocruz@gmail.com [Universidade Federal da Bahia (GECIM/UFBA), Salvador, BA (Brazil). Programa de Pos-Graduacao em Engenharia Quimica. Grupo de Energia e Ciencias dos Materiais

2014-07-01

Biodegradable films have become a widely exploited issue among scientists because of their positive environmental impact, besides their potential to promote better food conservation and an increase in shelf life. Starch has been studied in this field due to its availability, low cost and biodegradability. However, starch films tend to be brittle and they need addition of a plasticizer to enable their usage. In this work, starch films were synthesized with different carboxylic acids as plasticizers, aiming to observe the effect of the acids chain size in the final films properties. The acids used were: oxalic, succinic and adipic. The materials were produced by casting and characterized by DSC, TG, DRX e FTIR. It was observed that the acids chain size influenced on the thermal and structural properties of the films. (author)

Fatty acid biosynthesis VII. Substrate control of chain-length of products synthesised by rat liver fatty acid synthetase

DEFF Research Database (Denmark)

Hansen, Heinz Johs. Max; Carey, E.M.; Dils, R.

1970-01-01

- 1. Gas-liquid and paper chromatography have been used to determine the chain-lengths of fatty acids synthesised by purified rat liver fatty acid synthetase from [1-14C]acetyl-CoA, [1,3-14C2]malonyl-CoA and from [1-14C]acetyl-CoA plus partially purified rat liver acetyl-CoA carboxylase. - 2....... A wide range (C4:0–C18:0) of fatty acids was synthesised and the proportions were modified by substrate concentrations in the same manner as for purified rabbit mammary gland fatty acid synthetase. - 3. The relative amount of radioactivity incorporated from added acetyl-CoA and malonyl-CoA depended...... of long-chain fatty acids was synthesised from carboxylated acetyl-CoA than from added malonyl-CoA. - 5. It is suggested that acetyl-CoA carboxylase may carboxylate acetate bound to fatty acid synthetase....

Synthesis of new oxovanadium (IV) complexes of potential insulinmimetic activity with coumarin-3-carboxylic acid ligands and substituted derivatives

International Nuclear Information System (INIS)

Salas Fernandez, Paloma; Alvino de la Sota, Nora; Galli Rigo-Righi, Carla

2013-01-01

This work comprises the design and synthesis of four new oxovanadium (IV) complexes, a metal which possesses insulin-mimetic action. Coumarin-3-carboxylic acid and three of its 6 -and 6,8- derivatives were used as ligands. Coumarins are of interest due to their well-known biological properties and pharmacological applications; these include the insulino-sensibilizing effect of certain alcoxy-hydroxy-derivatives which might lead to the eventual existence of a synergetic effect with the active metal center. The synthesis of the vanadyl complexes was preceded by the synthesis of the coumarin-3-carboxylic acid and its 6-bromo- derivative, as well as the syntheses of three derivatives not previously reported: 6-bromo-8-metoxi-, 6-bromo-8-nitro-, and 6-bromo-8-hydroxy-, which were prepared by a Knoevenagel condensation reaction. The complexes, on their part, were prepared by a metathesis reaction between VOSO 4 and the corresponding ligands, on the basis of methods reported for other vanadyl complexes and under strict pH control. The coumarin-3-carboxylic ligands and the derivatives were characterized by 1 H-NMR-, FTIR- and UV-Vis-spectroscopy. In the case of the complexes, their paramagnetic character did not allow for NMR characterization, being thus identified by FT-IR-spectroscopy and by the quantitative determination of their vanadium contents. (author)

Polymorphism in Self-Assembled Structures of 9-Anthracene Carboxylic Acid on Ag(111

Directory of Open Access Journals (Sweden)

Bo Xu

2012-06-01

Full Text Available Surface self-assembly process of 9-anthracene carboxylic acid (AnCA on Ag(111 was investigated using STM. Depending on the molecular surface density, four spontaneously formed and one annealed AnCA ordered phases were observed, namely a straight belt phase, a zigzag double-belt phase, two simpler dimer phases, and a kagome phase. The two high-density belt phases possess large unit cells on the scale length of 10 nm, which are seldom observed in molecular self-assembled structures. This structural diversity stems from a complicated competition of different interactions of AnCA molecules on metal surface, including intermolecular and molecular-substrate interactions, as well as the steric demand from high molecular surface density.

Nuclear magnetic resonance titration studies of simple host-guest amine-carboxylic acid systems

International Nuclear Information System (INIS)

Mahinay, Myrna S.; Lindoy, Leonard F.

1999-01-01

Adduct formation for the open-chain 1,2-diaminoethane and its N-methyl derivatives [N,N-dimethyl-ethylenediamine (N,N-DMEN),N,N'-dimethylethylenediamine (N,N'-DMEN);N,N,N',N'-tetramethyl-ethylenediamine (N,N,N',N'-TMEN)]; 1,4-diaminobutane; diethylenetriamine (DIEN); triethylenetramine (TRIEN); and the carboxylic acid systems in polar CD 3 OH and nonpolar CDCl 3 solvents were elucidated by nmr titration. The stoichiometries of the adducts were found to correspond to the number of nitrogen present in the amine species with the exception of ligand incorporating N-donors of low basicity; that is, whose log K values for the protonated species in water were less than approximately 6 to 7.(Author)

Long-chain perfluoroalkyl carboxylic acids in Pacific cods from coastal areas in northern Japan: A major source of human dietary exposure

International Nuclear Information System (INIS)

Fujii, Yukiko; Sakurada, Tsukasa; Harada, Kouji H.; Koizumi, Akio; Kimura, Osamu; Endo, Tetsuya; Haraguchi, Koichi

2015-01-01

This study investigates perfluoroalkyl carboxylic acids (PFCAs) contamination of edible fish muscle from Japanese coastal waters. The concentrations of PFCAs with 8–14 carbon atoms (C8–C14) in Pacific cods in Hokkaido, Japan were 51 (median: pg/g-wet weight) for C8, 93 for C9, 99 for C10, 746 for C11, 416 for C12, 404 for C13, and 93 for C14. The levels of C9–C14 PFCAs in fish were strongly correlated to each other, but not to C8 and the other chlorinated persistent organic pollutants, indicating that C9–C14 PFCAs have a different emission source and/or bioaccumulation mechanism. The relative ratios between estimated PFCAs intake through fish consumption and the reported total dietary exposure of PFCAs were less than 1 for C8 to C9, but were more than 1 for C10 to C14. This result strongly suggests that fish consumption is a significant source of human dietary exposure to C10–C14 PFCAs. - Highlights: • Perfluoroalkyl carboxylic acids were detected in edible cod fish from Japanese coastal waters. • The levels of long-chain PFCAs in fish were independent from those of C8 and other POPs. • Long chain PFCAs intake through fish and the reported total dietary exposure were comparable. • Sea fish such as Pacific cod may be a significant human dietary source of long-chain PFCAs. - Sea fish are a significant source of long-chain perfluoroalkyl carboxylic acids for the Japanese population

A Single Enzyme Transforms a Carboxylic Acid into a Nitrile through an Amide Intermediate.

Science.gov (United States)

Nelp, Micah T; Bandarian, Vahe

2015-09-01

The biosynthesis of nitriles is known to occur through specialized pathways involving multiple enzymes; however, in bacterial and archeal biosynthesis of 7-deazapurines, a single enzyme, ToyM, catalyzes the conversion of the carboxylic acid containing 7-carboxy-7-deazaguanine (CDG) into its corresponding nitrile, 7-cyano-7-deazaguanine (preQ0 ). The mechanism of this unusual direct transformation was shown to proceed via the adenylation of CDG, which activates it to form the newly discovered amide intermediate 7-amido-7-deazaguanine (ADG). This is subsequently dehydrated to form the nitrile in a process that consumes a second equivalent of ATP. The authentic amide intermediate is shown to be chemically and kinetically competent. The ability of ToyM to activate two different substrates, an acid and an amide, accounts for this unprecedented one-enzyme catalysis of nitrile synthesis, and the differential rates of these two half reactions suggest that this catalytic ability is derived from an amide synthetase that gained a new function. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pentavalent Bismuth-Mediated Glycosylation Methods to Activate Sialic and Uronic Acids and the Incorporation of Sialic Acids Into Insulin

Science.gov (United States)

Kabotso, Daniel Elorm Kwame

The negative charge at physiological pH of carboxylic acid-containing monosaccharides modulate the properties of many natural biomolecules such as oligosaccharides and glycoconjugates. Unfortunately, these altered electronic properties also make the incorporation of such acidic sugars more challenging as compared to the more commonly studied neutral sugars. Herein are reported the first demonstration of glycosylation reactions mediated by triphenylbis(1,1,1-trifluoromethanesulfonato)-bismuth with thioglycosides containing carboxylic acid substituents protected as esters. Unlike with many neutral sugar substrates, the addition of 1-propanethiol to the reactions proved critical to obtaining good yields of the desired glycosylation products using sialic acid, galacturonic acid, and glucuronic acid. The protocol was demonstrated to be amenable to automation using a liquid-handling platform. The consequences of artificially incorporating carboxylic-acid-containing sugars into proteins were tested by the design of a linker containing 1 to 4 sialic acids--a sugar found in many human proteins and brain tissues--that was attached via reductive amination of trityl thiopropylaldehyde at the phenyl alanine terminal end of the protein insulin produced through solid-phase peptide synthesis. Removal of the trityl group with neat trifluoroacetic acid furnished the thiol-free modified insulin that was ligated via a disulfide bond to the peptide scaffold bearing acetyl protected sialic acids. A 14-15% ammonium hydroxide solution was found to be effective in deprotecting the acetyl groups without degradation of the disulfide bond. In addition to maintaining the potency and bioactivity of insulin, the sialic acid-containing linker rendered insulin more resistant to aggregation due to heat and mechanical agitation compared to the unmodified protein.

Aerosol Fragmentation Driven by Coupling of Acid-Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals.

Science.gov (United States)

Liu, Matthew J; Wiegel, Aaron A; Wilson, Kevin R; Houle, Frances A

2017-08-10

A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps with physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular

Extraction of cesium from acid solutions

International Nuclear Information System (INIS)

Katykhin, G.S.; Simonov, A.S.

1983-01-01

The extraction of cesium from acidic solutions is studied. Halogen-substituted carboxylic acids were chosen for the aqueous phase and nitrobenzene the diluent. The distribution coefficients are determined by the use of radioactive tracers 134 Cs and 137 Cs. It is believed that large singly charged anions of strong acids are necessary for the extraction of cesium. Metal halide acids are selected for supplying the anions

Mechanism of in situ surface polymerization of gallic acid in an environmental-inspired preparation of carboxylated core-shell magnetite nanoparticles.

Science.gov (United States)

Tóth, Ildikó Y; Szekeres, Márta; Turcu, Rodica; Sáringer, Szilárd; Illés, Erzsébet; Nesztor, Dániel; Tombácz, Etelka

2014-12-30

Magnetite nanoparticles (MNPs) with biocompatible coatings are good candidates for MRI (magnetic resonance imaging) contrasting, magnetic hyperthermia treatments, and drug delivery systems. The spontaneous surface induced polymerization of dissolved organic matter on environmental mineral particles inspired us to prepare carboxylated core-shell MNPs by using a ubiquitous polyphenolic precursor. Through the adsorption and in situ surface polymerization of gallic acid (GA), a polygallate (PGA) coating is formed on the nanoparticles (PGA@MNP) with possible antioxidant capacity. The present work explores the mechanism of polymerization with the help of potentiometric acid-base titration, dynamic light scattering (for particle size and zeta potential determination), UV-vis (UV-visible light spectroscopy), FTIR-ATR (Fourier-transformed infrared spectroscopy by attenuated total reflection), and XPS (X-ray photoelectron spectroscopy) techniques. We observed the formation of ester and ether linkages between gallate monomers both in solution and in the adsorbed state. Higher polymers were formed in the course of several weeks both on the surface of nanoparticles and in the dispersion medium. The ratio of the absorbances of PGA supernatants at 400 and 600 nm (i.e., the E4/E6 ratio commonly used to characterize the degree of polymerization of humic materials) was determined to be 4.3, similar to that of humic acids. Combined XPS, dynamic light scattering, and FTIR-ATR results revealed that, prior to polymerization, the GA monomers became oxidized to poly(carboxylic acid)s due to ring opening while Fe(3+) ions reduced to Fe(2+). Our published results on the colloidal and chemical stability of PGA@MNPs are referenced thoroughly in the present work. Detailed studies on biocompatibility, antioxidant property, and biomedical applicability of the particles will be published.

Determination of carboxyl groups in wood fibers by headspace gas chromatography

Science.gov (United States)

X.-S. Chai; Q.X. Hou; J.Y. Zhu; S.-L. Chen; S.F. Wang; L. Lucia

2003-01-01

The phase reaction conversion (PRC) headspace gas chromatographic (HSGC) technique was employed to develop a method for the determination of the content of carboxyl groups in wood fibers. Acid treatment of the wood fibers using hydrochloric was applied to convert carboxyl groups to carboxyl acids. Bicarbonate solution is then used to react with carboxyl acids on the...

Fe-Catalyzed Oxidative Cleavage of Unsaturated Fatty Acids

NARCIS (Netherlands)

Spannring, P.

2013-01-01

The oxidative cleavage of unsaturated fatty acids into aldehydes or carboxylic acids gives access to valuable products. The products can be used as chemical building blocks, as emulsifiers or in the paint or polymer industry. Ozonolysis is applied industrially to cleave the fatty acid oleic acid

Indium-Catalyzed Reductive Dithioacetalization of Carboxylic Acids with Dithiols: Scope, Limitations, and Application to Oxidative Desulfurization.

Science.gov (United States)

Nishino, Kota; Minato, Kohei; Miyazaki, Takahiro; Ogiwara, Yohei; Sakai, Norio

2017-04-07

In this study an InI 3 -TMDS (1,1,3,3-tetramethyldisiloxane) reducing system effectively catalyzed the reductive dithioacetalization of a variety of aromatic and aliphatic carboxylic acids with 1,2-ethanedithiol or 1,3-propanedithiol leading to the one-pot preparation of either 1,3-dithiolane derivatives or a 1,3-dithiane derivative. Also, the intact indium catalyst continuously catalyzed the subsequent oxidative desulfurization of an in situ formed 1,3-dithiolane derivative, which led to the preparation of the corresponding aldehydes.

PCI-GC-MS-MS approach for identification of non-amino organic acid and amino acid profiles.

Science.gov (United States)

Luan, Hemi; Yang, Lin; Ji, Fenfen; Cai, Zongwei

2017-03-15

Alkyl chloroformate have been wildly used for the fast derivatization of metabolites with amino and/or carboxyl groups, coupling of powerful separation and detection systems, such as GC-MS, which allows the comprehensive analysis of non-amino organic acids and amino acids. The reagents involving n-alkyl chloroformate and n-alcohol are generally employed for providing symmetric labeling terminal alkyl chain with the same length. Here, we developed an asymmetric labeling strategy and positive chemical ionization gas chromatography-tandem mass spectrometry (PCI-GC-MS-MS) approach for determination of non-amino organic acids and amino acids, as well as the short chain fatty acids. Carboxylic and amino groups could be selectively labelled by propyl and ethyl groups, respectively. The specific neutral loss of C 3 H 8 O (60Da), C 3 H 5 O 2 (74Da) and C 4 H 8 O 2 (88Da) were useful in the selective identification for qualitative analysis of organic acids and amino acid derivatives. PCI-GC-MS-MS using multiple reaction monitoring (MRM) was applied for semi-quantification of typical non-amino organic acids and amino acids. This method exhibited a wide range of linear range, good regression coefficient (R 2 ) and repeatability. The relative standard deviation (RSD) of targeted metabolites showed excellent intra- and inter-day precision (chloroformate derivatization. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis, Antifungal Activity and QSAR of Some Novel Carboxylic Acid Amides

Directory of Open Access Journals (Sweden)

Shijie Du

2015-03-01

Full Text Available A series of novel aromatic carboxylic acid amides were synthesized and tested for their activities against six phytopathogenic fungi by an in vitro mycelia growth inhibition assay. Most of them displayed moderate to good activity. Among them N-(2-(1H-indazol-1-ylphenyl-2-(trifluoromethylbenzamide (3c exhibited the highest antifungal activity against Pythium aphanidermatum (EC50 = 16.75 µg/mL and Rhizoctonia solani (EC50 = 19.19 µg/mL, compared to the reference compound boscalid with EC50 values of 10.68 and 14.47 µg/mL, respectively. Comparative molecular field analysis (CoMFA and comparative molecular similarity indices analysis (CoMSIA were employed to develop a three-dimensional quantitative structure-activity relationship model for the activity of the compounds. In the molecular docking, a fluorine atom and the carbonyl oxygen atom of 3c formed hydrogen bonds toward the hydroxyl hydrogens of TYR58 and TRP173.

An enantioselective approach toward 3,4-dihydroisocoumarin through the bromocyclization of styrene-type carboxylic acids.

Science.gov (United States)

Chen, Jie; Zhou, Ling; Tan, Chong Kiat; Yeung, Ying-Yeung

2012-01-20

A facile and enantioselective approach toward 3,4-dihydroisocoumarin was developed. The method involved an amino-thiocarbamate catalyzed enantioselective bromocyclization of styrene-type carboxylic acids, yielding 3-bromo-3,4-dihydroisocoumarins with good yields and ee's. 3-Bromo-3,4-dihydroisocoumarins are versatile building blocks for various dihydroisocoumarin derivatives in which the Br group can readily be modified to achieve biologically important 4-O-type and 4-N-type 3,4-dihydroisocoumarin systems. In addition, studies indicated that, by refining some parameters, the synthetically useful 5-exo phthalide products could be achieved with good yields and ee's.

Development and Validation of an HPLC Method for Simultaneous Quantification of Clopidogrel Bisulfate, Its Carboxylic Acid Metabolite, and Atorvastatin in Human Plasma: Application to a Pharmacokinetic Study

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Octavian Croitoru

2015-01-01

Full Text Available A simple, sensitive, and specific reversed phase liquid chromatographic method was developed and validated for simultaneous quantification of clopidogrel, its carboxylic acid metabolite, and atorvastatin in human serum. Plasma samples were deproteinized with acetonitrile and ibuprofen was chosen as internal standard. Chromatographic separation was performed on an BDS Hypersil C18 column (250 × 4.6 mm; 5 μm via gradient elution with mobile phase consisting of 10 mM phosphoric acid (sodium buffer solution (pH = 2.6 adjusted with 85% orthophosphoric acid : acetonitrile : methanol with flow rate of 1 mL·min−1. Detection was achieved with PDA detector at 220 nm. The method was validated in terms of linearity, sensitivity, precision, accuracy, limit of quantification, and stability tests. Calibration curves of the analytes were found to be linear in the range of 0.008–2 μg·mL−1 for clopidogrel, 0.01–4 μg·mL−1 for its carboxylic acid metabolite, and 0.005–2.5 μg·mL−1 for atorvastatin. The results of accuracy (as recovery with ibuprofen as internal standard were in the range of 96–98% for clopidogrel, 94–98% for its carboxylic acid metabolite, and 90–99% for atorvastatin, respectively.

The effect of omega-3 carboxylic acids on apolipoprotein CIII-containing lipoproteins in severe hypertriglyceridemia.

Science.gov (United States)

Morton, Allyson M; Furtado, Jeremy D; Lee, Jane; Amerine, William; Davidson, Michael H; Sacks, Frank M

Lipoprotein subspecies containing apoCIII adversely affect cardiovascular disease (CVD) risk; for example, low density lipoprotein (LDL) with apoCIII is a stronger CVD predictor than LDL without apoCIII. The Epanova for Lowering Very High Triglycerides (EVOLVE) trial showed that Epanova (omega-3 carboxylic acids [OM3-CA]) significantly lowered TG and apoCIII but raised LDL-C. However, it is unknown what subspecies of LDL were affected by treatment. To determine how lipoprotein subspecies are affected by omega-3 fatty acid treatment, we studied the effect of OM3-CA on apoCIII concentrations in high density lipoprotein (HDL), LDL, and very low density lipoprotein (VLDL) and on the concentrations of subspecies of HDL, LDL, and VLDL that contain or do not contain apoCIII. We analyzed plasma from a subset of subjects from the EVOLVE trial, a 12-week double-blind study of 399 subjects with fasting TG of 500 to 2000 mg/dL who were randomized to OM3-CA 2, 3, or 4 g/d or olive oil (placebo). OM3-CA significantly reduced plasma apoCIII relative to placebo, as well as apoCIII in HDL, and apoCIII in LDL. Treatment did not significantly affect the concentration of LDL with apoCIII, a subspecies highly associated with CVD risk. OM3-CA increased selectively the concentration of LDL that does not contain apoCIII, a subspecies with a weak relation to coronary heart disease. The reduction in apoCIII was associated with plasma increases in eicosapentaenoic acid, docosahexaenoic acid, and arachidonic acid and decreases in linoleic, palmitic, and oleic acids. Reduction in apoCIII may be a mechanism for the TG-lowering effects of OM3-CA. The increase in LDL-C seen in the EVOLVE trial may not be associated with increased risk of CVD. Copyright © 2016 National Lipid Association. Published by Elsevier Inc. All rights reserved.

Preparation of an aminopropyl imidazole-modified silica gel as a sorbent for solid-phase extraction of carboxylic acid compounds and polycyclic aromatic hydrocarbons.

Science.gov (United States)

Wang, Na; Guo, Yong; Wang, Licheng; Liang, Xiaojing; Liu, Shujuan; Jiang, Shengxiang

2014-05-21

In this paper, a kind of aminopropyl imidazole-modified silica sorbent was synthesized and used as a solid-phase extraction (SPE) sorbent for the determination of carboxylic acid compounds and polycyclic aromatic hydrocarbons (PAHs). The resultant aminopropyl imidazole-modified silica sorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA) to ensure the successful binding of aminopropyl imidazole on the surface of silica gel. Then the aminopropyl imidazole-modified silica sorbent served as a SPE sorbent for the enrichment of carboxylic acid compounds and PAHs. The new sorbent exhibited high extraction efficiency towards the tested compounds and the results show that such a sorbent can offer multiple intermolecular interactions: electrostatic, π-π, and hydrophobic interactions. Several parameters affecting the extraction recovery, such as the pH of sample solution, the pH of eluent, the solubility of eluent, the volume of eluent, and sample loading, were also investigated. Under the optimized conditions, the proposed method was applied to the analysis of four carboxylic acid compounds and four PAHs in environmental water samples. Good linearities were obtained for all the tested compounds with R(2) larger than 0.9903. The limits of detection were found to be in the range of 0.0065-0.5 μg L(-1). The recovery values of spiked river water samples were from 63.2% to 112.3% with relative standard deviations (RSDs) less than 10.1% (n = 4).

Copolymers Based on Indole-6-Carboxylic Acid and 3,4-Ethylenedioxythiophene as Platinum Catalyst Support for Methanol Oxidation

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Tzi-Yi Wu

2015-10-01

Full Text Available Indole-6-carboxylic acid (ICA and 3,4-ethylenedioxythiophene (EDOT are copolymerized electrochemically on a stainless steel (SS electrode to obtain poly(indole-6-carboxylic acid-co-3,4-ethylenedioxythiophenes (P(ICA-co-EDOTs. The morphology of P(ICA-co-EDOTs is checked using scanning electron microscopy (SEM, and the SEM images reveal that these films are composed of highly porous fibers when the feed molar ratio of ICA/EDOT is greater than 3/2. Platinum particles can be electrochemically deposited into the P(ICA-co-EDOTs and PICA films to obtain P(ICA-co-EDOTs-Pt and PICA-Pt composite electrodes, respectively. These composite electrodes are further characterized using X-ray photoelectron spectroscopy (XPS, SEM, X-ray diffraction analysis (XRD, and cyclic voltammetry (CV. The SEM result indicates that Pt particles disperse more uniformly into the highly porous P(ICA3-co-EDOT2 fibers (feed molar ratio of ICA/EDOT = 3/2. The P(ICA3-co-EDOT2-Pt nanocomposite electrode exhibited excellent catalytic activity for the electrooxidation of methanol in these electrodes, which reveals that P(ICA3-co-EDOT2-Pt nanocomposite electrodes are more promising for application in an electrocatalyst as a support material.

Charge-transfer excited state in pyrene-1-carboxylic acids adsorbed on titanium dioxide nanoparticles

Science.gov (United States)

Krawczyk, S.; Nawrocka, A.; Zdyb, A.

2018-06-01

The electronic structure of excited photosensitizer adsorbed at the surface of a solid is the key factor in the electron transfer processes that underlie the efficiency of dye-sensitized solar cells and photocatalysts. In this work, Stark effect (electroabsorption) spectroscopy has been used to measure the polarizability and dipole moment changes in electronic transitions of pyrene-1-carboxylic (PCA), -acetic (PAA) and -butyric (PBA) acids in ethanol, both free and adsorbed on colloidal TiO2, in glassy ethanol at low temperature. The lack of appreciable increase of dipole moment in the excited state of free and adsorbed PAA and PBA points that two or more single bonds completely prevent the expansion of π-electrons from the aromatic ring towards the carboxylic group, thus excluding the possibility of direct electron injection into TiO2. In free PCA, the pyrene's forbidden S0 → S1 transition has increased intensity, exhibits a long progression in 1400 cm-1 Ag mode and is associated with |Δμ| of 2 D. Adsorption of PCA on TiO2 causes a broadening and red shift of the S0 → S1 absorption band and an increase in dipole moment change on electronic excitation to |Δμ| = 6.5 D. This value increased further to about 15 D when the content of acetic acid in the colloid was changed from 0.2% to 2%, and this effect is ascribed to the surface electric field. The large increase of |Δμ| points that the electric field effect can not only change the energetics of electron transfer from the excited sensitizer into the solid, but can also shift the molecular electronic density, thus directly influencing the electronic coupling factor relevant for electron transfer at the molecule-solid interface.

Formation of organic acids from trace carbon in acidic oxidizing media

International Nuclear Information System (INIS)

Terrassier, C.

2003-01-01

Carbon 14 does not fully desorb as CO 2 during the hot concentrated nitric acid dissolution step of spent nuclear fuel reprocessing: a fraction is entrained in solution into the subsequent process steps as organic species. The work described in this dissertation was undertaken to identify the compounds arising from the dissolution in 3 N nitric acid of uranium carbides (selected as models of the chemical form of carbon 14 in spent fuel) and to understand their formation and dissolution mechanism. The compounds were present at traces in solution, and liquid-solid extraction on a specific stationary phase (porous graphite carbon) was selected to concentrate the monoaromatic poly-carboxylic acids including mellitic acid, which is mentioned in the literature but has not been formally identified. The retention of these species and of oxalic acid - also cited in the literature - was studied on this stationary phase as a function of the mobile phase pH, revealing an ion exchange retention mechanism similar to the one observed for benzyltrimethylammonium polystyrene resins. The desorption step was then optimized by varying the eluent pH and ionic strength. Mass spectrometry analysis of the extracts identified acetic acid, confirmed the presence of mellitic acid, and revealed compounds of high molecular weight (about 200 g/mol); the presence of oxalic acid was confirmed by combining gas chromatography and mass spectrometry. Investigating the dissolution of uranium and zirconium carbides in nitric acid provided considerable data on the reaction and suggested a reaction mechanism. The reaction is self-catalyzing via nitrous acid, and the reaction rate de pends on the acidity and nitrate ion concentration in solution. Two uranium carbide dissolution mechanisms are proposed: one involves uranium at oxidation state +IV in solution, coloring the dissolution solution dark green, and the other assumes that uranium monocarbide is converted to uranium oxide. The carboxylic acid

Frictional response of fatty acids on steel.

Science.gov (United States)

Sahoo, Rashmi R; Biswas, S K

2009-05-15

Self-assembled monolayers of fatty acids were formed on stainless steel by room-temperature solution deposition. The acids are covalently bound to the surface as carboxylate in a bidentate manner. To explore the effect of saturation in the carbon backbone on friction in sliding tribology, we study the response of saturated stearic acid (SA) and unsaturated linoleic acid (LA) as self-assembled monolayers using lateral force microscopy and nanotribometry and when the molecules are dispersed in hexadecane, using pin-on-disc tribometry. Over a very wide range (10 MPa-2.5 GPa) of contact pressures it is consistently demonstrated that the unsaturated linoleic acid molecules yield friction which is significantly lower than that of the saturated stearic acid. It is argued, using density functional theory predictions and XPS of slid track, that when the molecular backbone of unsaturated fatty acids are tilted and pressed strongly by a probe, in tribological contact, the high charge density of the double bond region of the backbone allows coupling with the steel substrate. The interaction yields a low friction carboxylate soap film on the substrate. The saturated fatty acid does not show this effect.

New trends and applications in carboxylation for isotope chemistry.

Science.gov (United States)

Bragg, Ryan A; Sardana, Malvika; Artelsmair, Markus; Elmore, Charles S

2018-05-08

Carboxylations are an important method for the incorporation of isotopically labeled 14 CO 2 into molecules. This manuscript will review labeled carboxylations since 2010 and will present a perspective on the potential of recent unlabeled methodology for labeled carboxylations. The perspective portion of the manuscript is broken into 3 major sections based on product type, arylcarboxylic acids, benzylcarboxylic acids, and alkyl carboxylic acids, and each of those sections is further subdivided by substrate. © 2018 AstraZeneca. Journal of Labelled Compounds and Radiopharmaceuticals Published by John Wiley & Sons, Ltd.

Oxidation of ethoxylated fatty alcohols to alkylpolyglycol carboxylic acids using noble metals as catalysts

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Sagredos, Angelos

2009-09-01

Full Text Available The conversion of ethoxylated fatty alcohols to the corresponding carboxylic acids through dehydrogenation/ oxidation using noble-metal catalysts has been studied. Ethoxylated primary aliphatic alcohols, ethoxylated random secondary aliphatic alcohols and ethoxylated alkylphenols have been converted to the corresponding acids in the presence of a base. The noble metal catalysts Palladium and Platinum were used without significant degradation of the ethoxyl chain in yields that exceeded 90%. On the other hand, the catalysts Rhodium and Ruthenium gave yields of about 80% and 60% respectively.La conversión de alcoholes grasos etoxilados a los correspondientes ácidos carboxílicos por deshidrogenación/ oxidación con metales nobles como catalizador ha sido estudiada. Alcoholes primarios alifáticos etoxilados, alcoholes alifáticos secundarios etoxilados al azar y alquilfenoles etoxilados han sido convertidos a los correspondientes ácidos en presencia de base. Los catalizadores paladio y platino fueron usados sin degradación significativa de las cadenas etoxiladas con un rendimiento que excedió del 90%. Por otra parte catalizadores de rodio y rutenio produjeron rendimientos del 80 y 60%, respectivamente.

A radioimmunoassay for abscisic acid

International Nuclear Information System (INIS)

Walton, D.; Dashek, W.; Galson, E.

1979-01-01

We have developed a radioimmunoassay (RIA) for abscisic acid (ABA) in the 0.1 ng to 2.5 ng range. Antibodies were obtained from rabbits immunized with ABA bound via its carboxyl group to bovine serum albumin. Cross-reactivity studies indicate that ABA esters are completely cross-reactive with ABA, while trans, trans abscisic acid (t-ABA) phaseic acid (PA) and dihydrophaseic acid (DPA) have much lower but significant cross-reactivities. Purification methods which reduce the levels of cross-reacting substances are described. (orig.) 891 AJ/orig. 892 MKO [de

Acid-base-controlled stereoselective metalation of overhanging carboxylic acid porphyrins: consequences for the formation of heterobimetallic complexes.

Science.gov (United States)

Le Gac, Stéphane; Najjari, Btissam; Dorcet, Vincent; Roisnel, Thierry; Fusaro, Luca; Luhmer, Michel; Furet, Eric; Halet, Jean-François; Boitrel, Bernard

2013-08-12

Overhanging carboxylic acid porphyrins have revealed promising ditopic ligands offering a new entry in the field of supramolecular coordination chemistry of porphyrinoids. Notably, the adjunction of a so-called hanging-atop (HAT) Pb(II) cation to regular Pb(II) porphyrin complexes allowed a stereoselective incorporation of the N-core bound cation, and an allosterically controlled Newton's cradle-like motion of the two Pb(II) ions also emerged from such bimetallic complexes. In this contribution, we have extended this work to other ligands and metal ions, aiming at understanding the parameters that control the HAT Pb(II) coordination. The nature of the N-core bound metal ion (Zn(II), Cd(II)), the influence of the deprotonation state of the overhanging COOH group and the presence of a neutral ligand on the opposite side (exogenous or intramolecular), have been examined through (1)H NMR spectroscopic experiments with the help of radiocrystallographic structures and DFT calculations. Single and bis-strap ligands have been considered. They all incorporate a COOH group hung over the N-core on one side. For the bis-strap ligands, either an ester or an amide group has been introduced on the other side. In the presence of a base, the mononuclear Zn(II) or Cd(II) complexes incorporate the carbonyl of the overhanging carboxylate as apical ligand, decreasing its availability for the binding of a HAT Pb(II). An allosteric effector (e.g., 4-dimethylaminopyridine (DMAP), in the case of a single-strap ligand) or an intramolecular ligand (e.g., an amide group), strong enough to compete with the carbonyl of the hung COO(-), is required to switch the N-core bound cation to the opposite side with concomitant release of the COO(-), thereby allowing HAT Pb(II) complexation. In the absence of a base, Zn(II) or Cd(II) binds preferentially the carbonyl of the intramolecular ester or amide groups in apical position rather than that of the COOH. This better preorganization, with the

Highly selective and efficient imprinted polymers based on carboxyl-functionalized magnetic nanoparticles for the extraction of gallic acid from pomegranate rind.

Science.gov (United States)

Zhang, Junjie; Li, Benqiang; Yue, Huijuan; Wang, Jing; Zheng, Yuansuo

2018-01-01

With the combined surface imprinting technique and immobilized template strategy, molecularly imprinted magnetic nanoparticles were successfully prepared and coupled with high-performance liquid chromatography to selectively separate and determine gallic acid from the pomegranate rind. On the surface of carboxyl-functionalized magnetic nanospheres, thin imprinting shells were formed using dopamine as monomer and crosslinker. The characteristics, polymerization conditions, and adsorption performances of the resultant nanomaterials were investigated in detail. In addition of good crystallinity, satisfactory magnetism, and uniform morphology of the obtained polymers, they had rapid binding kinetics, high adsorption capacity, and favorable reusability. In the mixed solution of four hydroxybenzoic acids, the prepared nanomaterials have an excellent selectivity to gallic acid with an imprinting factor of as high as 17.5. Therefore, the polymers have great potentials in specific extraction and enrichment of gallic acid from the complex natural resources. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous analysis of plasma free fatty acids and their 3-hydroxy analogs in fatty acid beta-oxidation disorders

NARCIS (Netherlands)

Costa, C. G.; Dorland, L.; Holwerda, U.; de Almeida, I. T.; Poll-The, B. T.; Jakobs, C.; Duran, M.

1998-01-01

We present a new derivatization procedure for the simultaneous gas chromatographic-mass spectrometric analysis of free fatty acids and 3-hydroxyfatty acids in plasma. Derivatization of target compounds involved trifluoroacetylation of hydroxyl groups and tert-butyldimethylsilylation of the carboxyl

Organic acids and aldehydes in rainwater in a northwest region of Spain

Energy Technology Data Exchange (ETDEWEB)

Pena, R.M.; Garcia, S.; Herrero, C. [Universidad de Santiago de Compostela, Lugo (Spain). Departamento de Quimica Analitica, Nutricion y Bromatologia

2002-11-01

During a 1 year period, measurements of carboxylic acids and aldehydes were carried out in rainwater samples collected at nine different sites in NW Spain surrounding a thermal power plant in order to determine concentration levels and sources. In addition, certain major ions (Cl{sup -}, NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, Na{sup +}, NH{sub 4}{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}) were also determined. Aldehyde and carboxylic acid concentration patterns and their effects on rainwater composition concerning temporal, seasonal and spatial variations were evaluated. Among carboxylic acids, formic and acetic were predominant (VWA 7.0 and 8.3 {mu}M), while formaldehyde and acroleine were the dominant aldehydes (VWA 0.42 and 1.25 {mu}M). Carboxylic acids were estimated to account for 27.5% of the total free acidity (TFA), whereas sulphuric and nitric acid accounted for 46.2% and 26.2%, respectively. Oxalic acid was demonstrated to be an important contributing compound to the acidification in rainwater representing 7.1% of the TFA. The concentration of aldehydes and carboxylic acids, which originated mainly from biogenic emissions in the area studied, was strongly dependent on the season of the year (growing and non-growing). The ratios of formic to acetic acids are considerably different in the two seasons suggesting that there exist distinct sources in both growing and non-growing seasons. Principal component analysis was applied in order to elucidate the sources of aldehydes and organic acids in rainwater. The prevalence of natural vegetative origins for both of these compounds versus anthropogenic emissions was demonstrated and the importance of the oxidation of aldehydes as a relevant source of organic acids was also established. (author)

Bioisosteric modifications of 2-arylureidobenzoic acids

DEFF Research Database (Denmark)

Valgeirsson, Jon; Nielsen, Elsebet O; Peters, Dan

2004-01-01

2-Arylureidobenzoic acids (AUBAs) have recently been presented as the first series of selective noncompetitive GluR5 antagonists. In this paper we have modified the acidic moiety of the AUBAs by introducing different acidic and neutral groups, and similarly, we have replaced the urea linker...... of the AUBAs with other structurally related linkers. Replacing the acid with neutral substituents led to inactive compounds in all instances, showing that an acidic moiety is necessary for activity. Replacing the carboxylic moiety in 2a with a sulfonic acid (5c) or a tetrazole ring (5d) improved the potency...

Dielectric properties of supramolecular ionic structures obtained from multifunctional carboxylic acids and amines

DEFF Research Database (Denmark)

Gonzalez, Lidia; Yu, Liyun; Hvilsted, Søren

2014-01-01

The dielectric properties of several supramolecular ionic polymers and networks, linked by the ammonium salts of hexamethylene diamine (HMDA), tris(2-aminoethyl)amine (TAEA), poly(propylene imine) (PPI) dendrimers and two short bis carboxymethyl ether-terminated poly(ethylene glycol)s (Di......COOH-PEG), are reported in this paper. All supramolecular ionic polymers and networks exhibit very high relative dielectric permittivities ( 3 0 )( 10 2 – 10 6 ) at low frequencies, and signi fi cantly lower values (from 1 up to 26) at high frequencies. Additionally, the dielectric properties of supramolecular ionic......), are investigated. Here the relative dielectric permittivities of the supramolecular ionic structures formed with the multifunctional carboxylic acids were lower than those from the supramolecular ionic structures formed with the two carboxymethyl ether-terminated poly(ethylene glycol)s....

Synthesis of new fatty acids amides from aminolysis of fatty acid methyl esters (FAMEs)

International Nuclear Information System (INIS)

Lopes, Carolina R.; Montes D'Oca, Caroline da Ros; Duarte, Rodrigo da C.; Kurz, Marcia H.S.; Primel, Ednei G.; Clementin, Rosilene M.; Villarreyes, Joaquin Ariel M.; Montes D'Oca, Marcelo G.

2010-01-01

Recent biochemical and pharmacological studies have led to the characterization of different fatty acid amides as a new family of biologically active lipids. Here, we describe the synthesis of new amides from C16:0, 18:0, 18:1 and 18:1, OH fatty acids (FFA) families with cyclic and acyclic amines and demonstrate for the first time that these compounds produce cytotoxic effects. Application of this method to the synthesis of fatty acid amides was performed using the esters aminolysis as a key step and various carboxylic amides were prepared in good yield from fatty acid methyl esters (FAMEs). (author)

Mechanisms for formation of organic acids in gas-phase reactions of ozone and hydroxyl radical with dialkenes and unsaturated carbonyls

Science.gov (United States)

Chien, Chao-Jung

2001-07-01

Carboxylic acids are ubiquitous throughout the troposphere and may contribute significant fractions of the free acidity in some remote areas. One of the important sources of these carboxylic acids is thought to be photochemical transformation of biogenic hydrocarbons such as isoprene. For the work reported here, atmospheric samples from University of North Carolina dual outdoor environmental chamber under simulated urban atmospheric conditions were analyzed for carboxylic acids. Both OH radicals and O3 initiated photooxidation reaction experiments were performed for isoprene, along with its structural analogs, 1,3-butadiene and 2,3-dimethyl-1,3-butadiene, and their primary photooxidation products, methacrolein, acrolein, and methyl vinyl ketone. Among the detected carboxylic acids were formic, acetic, and several multifunctional carboxylic acids, including methacrylic, acrylic, glyoxylic, and glycolic acids. Quantification of most carboxylic acid products was also established. Formation yields of carboxylic acids from the reactions of O3 with studied compounds were determined, and time-concentration series of the reactants and carboxylic acid products were measured to facilitate mechanism formulation. While the reaction mechanisms of Criegee biradicals arising from decomposition of primary ozonides are proposed to account for the observed carboxylic acid products in the ozonolysis of unsaturated hydrocarbons, reactions of peroxy acyl radicals with HO2 and/or other peroxy radicals are thought to be responsible for the formation of carboxylic acids during the OH-initiated reactions in the presence of NOx. In this study, smog chamber simulations have also been performed for selected compounds using Morpho, a photochemical kinetic simulation software package. Explicit photochemical mechanisms with O 3 and OH radicals that lead to formation of carboxylic acids were elaborated and implemented, and the simulation results were compared with those from other chemical

Recovery and esterification of aqueous carboxylates by using CO

NARCIS (Netherlands)

Cabrera-Rodríguez, Carlos I.; Paltrinieri, Laura; Smet, De Louis C.P.M.; Wielen, Van Der Luuk A.M.; Straathof, Adrie J.J.

2017-01-01

The recovery of carboxylic acids from fermentation broth is one of the main bottlenecks for the industrial production of bio-based esters. This paper proposes an alternative for the recovery of carboxylates produced by fermentations at pH values above the pKa of the carboxylic acid. In this

Tris[(6S)-6-hy-droxy-4-epi-shikimic acid] monohydrate: an enanti-omerically pure hy-droxy-lated shikimic acid derived from methyl shikimate.

Science.gov (United States)

Griesbeck, Axel G; Miara, Claus; Neudörfl, Jörg-M

2012-11-01

The title compound, 3C(7)H(10)O(6)·H(2)O, is the enanti-omerically pure product of a multi-step synthesis from the enanti-omerically pure natural shikimic acid. The asymmetric unit contains three mol-ecules of the acid and one mol-ecule of water. The cyclo-hexene rings of the acids have half-chair conformations. The carboxyl-ate, the four hydroxide groups and the additional water mol-ecule form a complex three-dimensional hydrogen-bonding network.

Fatty acid biosynthesis. VIII. The fate of malonyl-CoA in fatty acid biosynthesis by purified enzymes from lactating-rabbit mammary gland

DEFF Research Database (Denmark)

Hansen, Heinz Johs. Max; Carey, E.M.; Dils, R.

1971-01-01

- 1. We have investigated the formation and utilization of malonyl-CoA in fatty acid synthesis catalysed by preparations of partially purified acetyl-CoA carboxylase and purified fatty acid synthetase from lactating-rabbit mammary gland. - 2. Carboxylation of [1-14C]acetyl-CoA was linked to fatty...... acid synthesis by the presence of fatty acid synthetase and NADPH. The rate of fatty acid formation was equal to that of acetyl-CoA carboxylation, without the accumulation of free malonyl-CoA to a concentration required to obtain the same rate of fatty acid synthesis from added [1,3-14C2]malonyl......-CoA. - 3. The preparations of acetyl-CoA carboxylase and fatty acid synthetase were each able to decarboxylate [1,3-14C2]malonyl-CoA. - 4. Both enzyme preparations acted as competitive inhibitors of 14CO2 fixation into acetyl-CoA catalysed by acetyl-CoA carboxylase in the absence of NADPH...

Application of monocarboxylic acids for the extraction of metal ions-literature survey

International Nuclear Information System (INIS)

Brzozka, Z.; Rozycki, C.

1980-01-01

In the paper there is presented a literature review concerning the application of monocarboxylic acids for extraction of metal ions. The following problems are discussed: characteristic of monocarboxylic acids and their mixtures, the equilibria between the acid solution in organic solvent and aqueous phase, the mechanism of acid partition, complexes of carboxylic acids and metal ions in aqueous phase, mechanism of extraction by means of carboxylic acids as well as the problems concerning the extraction of individual metal ions. Data about the extraction of metal ions are presented in table. The 138 references are given. (author)

4-Hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester derivatives as potent anti-tumor agents.

Science.gov (United States)

Hayakawa, Ichiro; Shioya, Rieko; Agatsuma, Toshinori; Furukawa, Hidehiko; Naruto, Shunji; Sugano, Yuichi

2004-01-19

Based on the structure of 4-hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester (1), which exhibits selective cytotoxicity against a tumorigenic cell line, (2,4-dimethoxyphenyl)-(4-hydroxy-3-methyl-6-phenylbenzofuran-2-yl)-methanone (18m) was designed and synthesized as a biologically stable derivative containing no ester group. Although the potency of 18m was almost the same as our initial hit compound 1, 18m is expected to last longer in the human body as an anticancer agent.

The use of fatty acid esters to enhance free acid sophorolipid synthesis.

Science.gov (United States)

Ashby, Richard D; Solaiman, Daniel K Y; Foglia, Thomas A

2006-02-01

Fatty acid esters were prepared by transesterification of soy oil with methanol (methyl-soyate, Me-Soy), ethanol (ethyl-soyate, Et-Soy) and propanol (propyl-soyate, Pro-Soy) and used with glycerol as fermentation substrates to enhance production of free-acid sophorolipids (SLs). Fed-batch fermentations of Candida bombicola resulted in SL yields of 46 +/- 4 g/l, 42 +/- 7 g/l and 18 +/- 6 g/l from Me-Soy, Et-Soy, and Pro-Soy, respectively. Liquid chromatography with atmospheric pressure ionization mass spectrometry (LC/API-MS) showed that Me-Soy resulted in 71% open-chain SLs with 59% of those molecules remaining esterified at the carboxyl end of the fatty acids. Et-Soy and Pro-Soy resulted in 43% and 80% open-chain free-acid SLs, respectively (containing linoleic acid and oleic acid as the principal fatty acid species linked to the sophorose sugar at the omega-1 position), with no evidence of residual esterification.

Incorporation of oxygen into abscisic acid and phaseic acid for molecular oxygen

International Nuclear Information System (INIS)

Creelman, R.A.; Zeevaart, J.A.D.

1984-01-01

Abscisic acid accumulates in detached, wilted leaves of Xanthium strumariu. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% 18 O 2 and 80% N 2 indicates that one atom of 18 O is incorporated in the 6'-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase. Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing 18 O 2 indicates that one atom of 18 O is presented in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-streesed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggest that either (a) the oxygen present in the 1'-, 4'-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1'- and 4'-positions of abscisic acid which is converted to abscisic acid under conditions of water stress. 17 references, 2 figures, 1 tables

Incorporation of oxygen into abscisic Acid and phaseic Acid from molecular oxygen.

Science.gov (United States)

Creelman, R A; Zeevaart, J A

1984-05-01

Abscisic acid accumulates in detached, wilted leaves of Xanthium strumarium. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% (18)O(2) and 80% N(2) indicates that one atom of (18)O is incorporated in the 6'-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase.Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing (18)O(2) indicates that one atom of (18)O is present in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-stressed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggests that either (a) the oxygen present in the 1'-, 4'-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1'- and 4'-positions of abscisic acid which is converted to abscisic acid under conditions of water stress.

A combined experimental and computational thermodynamic study of fluorene-9-methanol and fluorene-9-carboxylic acid

International Nuclear Information System (INIS)

Oliveira, Juliana A.S.A.; Calvinho, Maria M.; Notario, R.; Monte, Manuel J.S.; Ribeiro da Silva, Maria D.M.C.

2013-01-01

Highlights: • A thermodynamic study of two fluorene derivatives is presented. • Vapour pressures and energies of combustion were measured. • Enthalpy, entropy and Gibbs energy of sublimation were derived. • Enthalpy and Gibbs energy of formation in crystal and gas phases were calculated. • Gas phase enthalpy of formation was also estimated by quantum chemical calculations. -- Abstract: This work reports an experimental and computational thermodynamic study performed on two 9-fluorene derivatives: fluorene-9-methanol and fluorene-9-carboxylic acid. The standard (p o = 0.1 MPa) molar enthalpies of formation in the crystalline phase of these compounds were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. A static method, based on a capacitance diaphragm gauge, and a Knudsen effusion method were used to perform the vapour pressure study of the referred compounds, yielding accurate determination of the standard molar enthalpies and entropies of sublimation and vaporisation. For fluorene-9-carboxylic acid, the enthalpy of sublimation was also determined using Calvet microcalorimetry. The enthalpy of fusion of both compounds was derived indirectly from vapour pressure results and directly from DSC experiments. Combining the thermodynamic parameters of the compounds studied, the standard Gibbs energy of formation in crystalline and gaseous phases were derived as well as the standard molar enthalpy of formation in the gaseous phase. A theoretical study at the G3 and G4 levels has been carried out, and the calculated enthalpies of formation have been compared with the experimental values

Effects of oxidizing adulterants on detection of 11-nor-delta9-THC-9-carboxylic acid in urine.

Science.gov (United States)

Paul, Buddha D; Jacobs, Aaron

2002-10-01

Bleach, nitrite, chromate, and hydrogen peroxide-peroxidase are effective urine adulterants used by the illicit drug users to conceal marijuana-positive results. Methods for detecting nitrite and chromate are available. Effects of other oxidizing agents that could possibly be used as adulterants and are difficult to detect or measure are presented in this report. Urine samples containing 40 ng/mL of 11-nor-delta9-THC-9-carboxylic acid (THC-acid) were treated with 10 mmol/L of commonly available oxidizing agents. Effects of horseradish peroxidase of activity 10 unit/mL and extracts from 2.5 g of red radish (Raphanus sativus, Radicula group), horseradish (Armoracia rusticana), Japanese radish (Raphanus sativus, Daikon group), and black mustard seeds (Brassica nigra), all with 10 mmol/L of hydrogen peroxide, were also examined. After 5 min, 16 h and 48 h of exposure at room temperature (23 degrees C) the specimens were tested by a gas chromatographic-mass spectrometric method for THC-acid. A control group treated with sodium hydrosulfite to reduce the oxidants, was also tested to investigate the effect of oxidizing agents on THC-acid in the extraction method. THC-acid was lost completely in the extraction method when treated with chromate, nitrite, oxone, and hydrogen peroxide/ferrous ammonium sulfate (Fenton's reagent). Some losses were also observed with persulfate and periodate (up to 25%). These oxidants, and other oxidizing agents like permanganate, periodate, peroxidase, and extracts from red radish, horseradish, Japanese radish and black mustard seeds destroyed most of the THC-acid (> 94%) within 48 h of exposure. Chlorate, perchlorate, iodate, and oxychloride under these conditions showed little or no effect. Complete loss was observed when THC-acid was exposed to 50 mmol/L of oxychloride for 48 h. Several oxidizing adulterants that are difficult to test by the present urine adulterant testing methods showed considerable effects on the destruction of THC-acid

Behenic acid pyrolysis to produce diesel-like hydrocarbons

International Nuclear Information System (INIS)

Xu, Zhi-Xiang; Liu, Peng; Xu, Gui-Sheng; He, Zhi-Xia; Ji, Heng-Song; Wang, Qian

2017-01-01

Highlights: • Behenic acid is a suitable bio-renewable resource to produce bio-fuel oil using catalytic cracking. • Little fraction of aromatic compounds presented in bio-fuel oil. • Carbon chain of fatty acid was cracked to form short carbon chain carboxyl firstly. • ESI FT-ICR MS experiment was an effective method to analyze bio-fuel oil heavy compounds. - Abstract: In order to obtain diesel-like bio-fuel oil, behenic acid was selected to carry out fast pyrolysis. The decomposition temperature of behenic acid was in the range of 250–450 °C at 20 k/min according to TG experiment. The bio-fuel oil mainly contained alkane, alkene and fatty acid. Components of products were C_1_3–C_2_0 hydrocarbon. Little fraction of aromatic compounds was found in bio-fuel oil. According to ESI FT-ICR MS analysis results, the oxygen containing compounds in bio-fuel oil were mainly O_2–O_4 classes, with the O_3 being the major class. According to GC–MS and ESI FT-ICR MS results, it was found that the carbon chain of behenic acid was cracked to form short carbon chain carboxyl firstly. And then decarboxylation reaction carried out. In other means carboxyl groups were more stable than carbon chain of fatty acid. The probable mechanism of O_4 species was free radical reaction. The recommended pyrolysis path was also proposed. Diesel-like bio-fuel oil can be obtained using behenic acid catalytic cracking.

Sugar amino acids and related molecules

Indian Academy of Sciences (India)

Sugar amino acids constitute an important class of such polyfunctional scaffolds where the carboxyl, amino and hydroxyl termini provide an excellent opportunity to organic chemists to create structural diversities akin to Nature's molecular arsenal. In recent years, sugar amino acids have been used extensively in the area of ...

Acute toxicity assessment of perfluorinated carboxylic acids towards the Baltic microalgae.

Science.gov (United States)

Latała, Adam; Nędzi, Marcin; Stepnowski, Piotr

2009-09-01

The presence of high-energy carbon-fluorine bonds in perfluoro compounds lends them great stability and causes them to be environmentally persistent. Relatively little is known about the acute toxicity of perfluorinated carboxylic acids (PFCAs) to ecotoxicological markers such as aquatic plants and animals. This study tested the toxicity of these compounds to the green alga Chlorella vulgaris, the diatom Skeletonema marinoi and the blue-green alga Geitlerinema amphibium, which are species representative of the algal flora of the Baltic Sea. The EC(50) values obtained range from 0.28 mM to 12.84 mM. A distinct relationship between hydrophobicity and toxicity is demonstrated. For every extra perfluoromethylene group in the alkyl chain, the toxicity increases twofold. LogEC(50) values are very well correlated linearly with both the number of carbon atoms in the perfluoroalkyl chain and the partition coefficients. The results also indicate that there are clear differences between the responses of particular taxonomic groups of algae: blue-green algae and diatoms are far more sensitive to PFCAs than green algae, probably because of differences in cell wall structure.

Vaporization of protic ionic liquids derived from organic superbases and short carboxylic acids.

Science.gov (United States)

Ribeiro, Filipe M S; Lima, Carlos F R A C; Vaz, Inês C M; Rodrigues, Ana S M C; Sapei, Erlin; Melo, André; Silva, Artur M S; Santos, Luís M N B F

2017-06-28

This work presents a comprehensive evaluation of the phase behaviour and cohesive enthalpy of protic ionic liquids (PILs) composed of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) organic superbases with short-chain length (acetic, propionic and butyric) carboxylic acids. Glass transition temperatures, T g , and enthalpies of vaporization, ΔH vap , were measured for six [BH][A] (1 : 1) PILs (B = DBN, DBU; A = MeCOO, EtCOO, nPrCOO), revealing more significant changes upon increasing the number of -CH 2 - groups in the base than in the acid. The magnitude of ΔH vap evidences that liquid PILs have a high proportion of ions, although the results also indicate that in DBN PILs the concentration of neutral species is not negligible. In the gas phase, these PILs exist as a distribution of ion pairs and isolated neutral species, with speciation being dependent on the temperature and pressure conditions - at high temperatures and low pressures the separated neutral species dominate. The higher T g and ΔH vap of the DBU PILs are explained by the stronger basicity of DBU (as supported by NMR and computational calculations), which increases the extent of proton exchange and the ionic character of the corresponding PILs, resulting in stronger intermolecular interactions in condensed phases.

Fatty Acid-Based Monomers as Styrene Replacements for Liquid Molding Resins

Science.gov (United States)

2005-05-01

fatty acid length and unsaturation level on resin and polymer properties. Fig. 2. The addition of fatty acids ( oleic acid ) to glycidyl methacylate to...the synthetic route used to form the methacrylated fatty acids (MFA). The carboxylic acid of fatty acids undergoes a simple addition reaction with... form methacrylated fatty acid monomer

HISTOPATHOLOGICAL EFFECTS OF (4S)-2-(4-HYDROXY-3-METHOXYPHENYL) THIAZOLIDINE-4-CARBOXYLIC ACID ON ZEBRAFISH (Danio rerio) HEART TISSUE

OpenAIRE

YÖN, Nazan Deniz; ÖZTÜRK, Burcu; ZENGİN, Mustafa; AKBULUT, Cansu

2018-01-01

Examination thehistopathological effects of (4s)-2-(4-hydroxy-3-methoxyphenyl) thiazolidine-4-carboxylicacid on heart tissue of zebrafish were aimed.Introduction:(4S)-2-(4-hydroxy-3-methoxyphenyl) thiazolidine-4-carboxylic acid is newsynthesized substance which obtained from cysteine and valine. Because ofthiazolidine derivates have important biological responses scientist workintensively on these compounds recent years. It is obvious that thiazolidinecontained compounds will be used in futur...

Study of the electronic structure at the interface between fluorene-1-carboxylic acid molecules and Cu(110)

International Nuclear Information System (INIS)

Song Fei; Mao Hongying; Guan Dandan; Dou Weidong; Zhang Hanjie; Li Haiyang; He Pimo; Bao Shining; Hofmann, Philip

2009-01-01

The interface electronic properties of fluorene-1-carboxylic acid (FC-1) adsorbed on Cu(110) have been studied by ultraviolet photoemission spectroscopy (UPS) and first-principles calculations. Both the molecular orbitals and the Cu valence band are significantly modified upon adsorption. FC-1 is chemically bonded to Cu(110) through charge donation and back donation involving the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of the molecule. An observed reduction of the work function can be attributed to the adsorption induced charge redistribution, and the positive interface dipole.

Reactive extraction of carboxylic acids from apolar hydrocarbons using aqueous solutions of sodium hydrogen carbonate with back-recovery using carbon dioxide under pressure

NARCIS (Netherlands)

Kuzmanovic, B.; Kuipers, N.J.M.; de Haan, A.B.; Kwant, Gerard

2005-01-01

A combination of using an aqueous solution of sodium hydrogen carbonate for forward-extraction of carboxylic acids from a dilute apolar organic solvent, and carbon dioxide under pressure for its back-recovery, is studied. Used in combination, these two steps might provide a technique for the

A chromene and prenylated benzoic acid from Piper aduncum.

Science.gov (United States)

Baldoqui, D C; Kato, M J; Cavalheiro, A J; Bolzani, V da S; Young, M C; Furlan, M

1999-08-01

In addition to nerolidol, 2',6'-dihydroxy-4'-methoxydihydrochalcone, methyl 2,2-dimethyl-8-(3'-methyl-2'-butenyl)-2H-1-chromene-6-carboxylate, methyl 2,2-dimethyl-2H-1-chromene-6-carboxylate and methyl 8-hydroxy-2,2-dimethyl-2H-1-chromene-6-carboxylate, two new natural products were isolated from the leaves of Piper aduncum, 2,2-dimethyl-2H-1-chromene-6-carboxylic acid and 3-(3',7'-dimethyl-2',6'-octadienyl)-4-methoxybenzoic acid. The structures of the isolates were established based on analysis of spectroscopic data, including ES-MS. The DNA-damaging activity of the isolated compounds was also investigated against mutant strains of Saccharomyces cerevisiae.

Transport of amino acids and GABA analogues via the human proton-coupled amino acid transporter, hPAT1

DEFF Research Database (Denmark)

Larsen, Mie; Larsen, Birger Brodin; Frølund, Bente

2008-01-01

The objective of this study was to investigate transepithelial amino acid transport as a function of Caco-2 cell culture time. Furthermore, the objective was to investigate apical uptake characteristics of hPAT1-mediated transport under various experimental conditions. Apical amino acid uptake......, which has been shown to function as a carboxylic acid bioisostere for substrates of the GABA receptor and transport systems....

Cinnamic Acid Derivatives as Antidiabetics Agents

Directory of Open Access Journals (Sweden)

Teni Ernawati

2017-04-01

Full Text Available Diabetes mellitus is a metabolic disorder of carbohydrate metabolism. Treatment of type II diabetes is usually done by prescribing diet and exercise for the patient however it can also be treated with antidiabetic drugs. The purpose of this paper is to illustrate some cinnamic acid derivative compounds which are either isolated from natural materials or the results of the chemical synthesis. In addition, their biological activities as an agent of α-glucosidase inhibitors have also been evaluated. Chemically, cinnamic acid has three main functional groups:  first is the substitution on the phenyl group, second is the additive reaction into the α-β unsaturated, and third is the chemical reaction with carboxylic acid functional groups. Chemical aspects of cinnamic acid derivative compounds have received much attention in the research and development of drugs, especially modifications within three functional groups are very influential. In the last 10 years, a lot of research and development of cinnamic acid derivatives as inhibitors of the α-glucosidase enzyme has been done. One example of the research done in this field is the modification of para position in the structure of cinnamic acid and addition of alkyl groups in the carboxylic group which would increase the activity of the α-glucosidase enzyme therefore the level of inhibition is 100 times higher than that of cinnamic acid compound itself. The novelty of this review article is to focus on the antidiabetic activity of cinnamic acid derivatives.

Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

Directory of Open Access Journals (Sweden)

Ruth Gomes

2014-11-01

Full Text Available A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state 13C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N2 sorption, HR-TEM, and NH3 temperature programmed desorption-thermal conductivity detector (TPD-TCD analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, β-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

Incorporation of Oxygen into Abscisic Acid and Phaseic Acid from Molecular Oxygen 1

Science.gov (United States)

Creelman, Robert A.; Zeevaart, Jan A. D.

1984-01-01

Abscisic acid accumulates in detached, wilted leaves of Xanthium strumarium. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% 18O2 and 80% N2 indicates that one atom of 18O is incorporated in the 6′-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase. Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing 18O2 indicates that one atom of 18O is present in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-stressed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggests that either (a) the oxygen present in the 1′-, 4′-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1′- and 4′-positions of abscisic acid which is converted to abscisic acid under conditions of water stress. PMID:16663564

Zeolite-catalysed preparation of alpha-hydroxy carboxylic acids and esters thereof

DEFF Research Database (Denmark)

2010-01-01

A process for the production of lactic acid and 2-hydroxy-3-butenoic acid or esters thereof by conversion of glucose, fructose, sucrose, xylose and glycolaldehyde dissolved in a solvent in presence of a solid Lewis acidic catalyst.......A process for the production of lactic acid and 2-hydroxy-3-butenoic acid or esters thereof by conversion of glucose, fructose, sucrose, xylose and glycolaldehyde dissolved in a solvent in presence of a solid Lewis acidic catalyst....

Selenium speciation in urine by ion-pairing chromatography with perfluorinated carboxylic acids and ICP-MS detection

DEFF Research Database (Denmark)

Gammelgaard, Bente; Bendahl, L.; Sidenius, U.

2002-01-01

Five aqueous standards, selenomethionine (SeMet), methylselenomethionine (MeSeMet), methylselenocysteine (MeSeCys), selenogammaaminobutyric acid (SeGaba) and the trimethylselenonium ion (TMSe), were separated in ion-pairing chromatographic systems based on perfluorinated carboxylic acids in metha...... were major compounds in urine samples-even after massive consumption of selenium-containing supplements. The selenium species in the urine samples showed a limited stability, as they changed during storage at +4 degreesC as well as -18 degreesC...... of between 2.3 and 5.1 pg. Urine samples from different individuals before and during supplementation with selenomethionine were analysed. Several species were separated in the different urine samples. A major component eluting at the beginning of the chromatogram was predominant in many samples, especially...... after selenium consumption. This species was not identified and solid phase extraction experiments suggested that it was neutral. When different urine samples were spiked with the available standards, co-elution of species with TMSe, MeSeMet or SeMet was observed in some samples. None of these species...

Interaction between Al3+ and acrylic acid and polyacrylic acid in acidic aqueous solution: a model experiment for the behavior of Al3+ in acidified soil solution.

Science.gov (United States)

Etou, Mayumi; Masaki, Yuka; Tsuji, Yutaka; Saito, Tomoyuki; Bai, Shuqin; Nishida, Ikuko; Okaue, Yoshihiro; Yokoyama, Takushi

2011-01-01

From the viewpoint of the phytotoxicity and mobility of Al(3+) released from soil minerals due to soil acidification, the interaction between Al(3+) and acrylic acid (AA) and polyacrylic acid (PAA) as a model compound of fulvic acid was investigated. The interaction was examined at pH 3 so as to avoid the hydrolysis of Al(3+). The interaction between Al(3+) and AA was weak. However, the interaction between Al(3+) and PAA was strong and depended on the initial (COOH in PAA)/Al molar ratio (R(P)) of the solution. For the range of 1/R(P), the interaction between Al(3+) and PAA can be divided into three categories: (1) 1:1 Al-PAA-complex (an Al(3+) combines to a carboxyl group), (2) intermolecular Al-PAA-complex (an Al(3+) combines to more than 2 carboxyl groups of other Al-PAA-complexes) in addition to the 1:1 Al-PAA-complex and (3) precipitation of intermolecular complexes. In conclusion, R(P) is an important factor affecting the behavior of Al(3+) in acidic soil solution.

HTGR fuel development: loading of uranium on carboxylic acid cation-exchange resins using solvent extraction of nitrate

International Nuclear Information System (INIS)

Haas, P.A.

1975-09-01

The reference fuel kernel for recycle of 233 U to HTGR's (High-Temperature Gas-Cooled Reactors) is prepared by loading carboxylic acid cation-exchange resins with uranium and carbonizing at controlled conditions. The purified 233 UO 2 (NO 3 ) 2 solution from a fuel reprocessing plant contains excess HNO 3 (NO 3 - /U ratio of approximately 2.2). The reference flowsheet for a 233 U recycle fuel facility at Oak Ridge uses solvent extraction of nitrate by a 0.3 M secondary amine in a hydrocarbon diluent to prepare acid-deficient uranyl nitrate. This nitrate extraction, along with resin loading and amine regeneration steps, was demonstrated in 14 runs. No significant operating difficulties were encountered. The process is controlled via in-line pH measurements for the acid-deficient uranyl nitrate solutions. Information was developed on pH values for uranyl nitrate solution vs NO 3 - /U mole ratios, resin loading kinetics, resin drying requirements, and other resin loading process parameters. Calculations made to estimate the capacities of equipment that is geometrically safe with respect to control of nuclear criticality indicate 100 kg/day or more of uranium for single nitrate extraction lines with one continuous resin loading contactor or four batch loading contactors. (auth)

Gamma-irradiation of malic acid in aqueous solutions. [prebiotic significance

Science.gov (United States)

Negron-Mendoza, A.; Graff, R. L.; Ponnamperuma, C.

1980-01-01

The gamma-irradiation of malic acid in aqueous solutions was studied under initially oxygenated and oxygen-free conditions in an attempt to determine the possible interconversion of malic acid into other carboxylic acids, specifically those associated with Krebs cycle. The effect of dose on product formation of the system was investigated. Gas-liquid chromatography combined with mass spectrometry was used as the principal means of identification of the nonvolatile products. Thin layer chromatography and direct probe mass spectroscopy were also employed. The findings show that a variety of carboxylic acids are formed, with malonic and succinic acids in greatest abundance. These products have all been identified as being formed in the gamma-irradiation of acetic acid, suggesting a common intermediary. Since these molecules fit into a metabolic cycle, it is strongly suggestive that prebiotic pathways provided the basis for biological systems.

Determination of carboxylic acids, carbohydrates and metals in different tomato cultivars by HPLC-ICP-AES in a single chromatographic run

OpenAIRE

Paredes Paredes, Eduardo; Maestre, Salvador E.; Prats Moya, Soledad; Todolí Torró, José Luis

2007-01-01

Póster presentado en European Winter Conference on Plasma Spectrochemistry 2007, 18-23 February 2007, Taormina, Italy The determination of carbohydrates, carboxylic acids and metals is a subject of great interest in the field of food science because their presence and concentration can influence on food quality. Besides the study of the profiles of these compounds can permit the discrimination between different varieties of a product. Unfortunately, the usually employed chromatograph...

Structure and photoluminescence property of complexes of aromatic carboxylic acid-functionalized polysulfone with Eu(Ⅲ) and Tb(Ⅲ)

International Nuclear Information System (INIS)

Gao, Baojiao; Qiao, Zongwen; Chen, Tao

2014-01-01

With chloromethylated polysulfone as starting substance, naphthoic acid (NA) and benzoic acid (BA) were bonded onto the side chains of polysulfone (PSF) via polymer reactions, obtaining two kinds of aromatic carboxyl acid-functionalized polysulfone, PSFNA and PSFBA. Subsequently, the luminescent binary and ternary polymer-rare earth complexes of Eu(Ⅲ) and Tb(Ⅲ) were prepared through coordination reactions, respectively, with PSFNA and PSFBA as macromolecule ligands and with 1,10-phenanthroline (Phen) and 4,4′-bipyridine (Bipy) as small-molecule co-ligands. This work focuses on investigating the relationship between structure and photoluminescence property of these complexes. The experimental results indicate that the macromolecule ligands PSFNA and PSFBA can strongly sensitize the fluorescence emissions of Eu 3+ ion or Tb 3+ ion, and the sensitization effect is strongly dependent on the structure of the ligands and the property of the central ions. The fluorescence emission of the binary complex PSF–(NA) 3 –Eu(Ⅲ) is stronger than that PSF–(BA) 3 –Eu(Ⅲ), suggesting the bonded ligand NA has stronger sensitization action for Eu 3+ ion than ligand BA; The binary complex PSF–(BA) 3 –Tb(Ⅲ) emit very strong characteristic fluorescence of Tb 3+ ion, displaying that ligand BA can strongly sensitize Tb 3+ ion, whereas PSF–(NA) 3 –Tb(Ⅲ) does not emit the characteristic fluorescence of Tb 3+ ion, showing that the bonded ligand NA does not sensitize Tb 3+ ion. The fluorescence intensity of the ternary complexes is stronger than that of the binary complexes in the same series. The solid films of these complexes also emit the strong characteristic fluorescence of Eu 3+ ion or Tb 3+ ion. - Highlights: • We prepared two kinds of aromatic carboxyl acid-functionalized polysulfone, PSFNA and PSFBA via polymer reaction. • Various binary and ternary luminescent polymer-rare earth complexes of Eu(Ⅲ) and Tb (Ⅲ) were obtained. • The relationship

Unravelling the surface chemistry of metal oxide nanocrystals, the role of acids and bases.

Science.gov (United States)

De Roo, Jonathan; Van den Broeck, Freya; De Keukeleere, Katrien; Martins, José C; Van Driessche, Isabel; Hens, Zeger

2014-07-09

We synthesized HfO2 nanocrystals from HfCl4 using a surfactant-free solvothermal process in benzyl alcohol and found that the resulting nanocrystals could be transferred to nonpolar media using a mixture of carboxylic acids and amines. Using solution (1)H NMR, FTIR, and elemental analysis, we studied the details of the transfer reaction and the surface chemistry of the resulting sterically stabilized nanocrystals. As-synthesized nanocrystals are charge-stabilized by protons, with chloride acting as the counterion. Treatment with only carboxylic acids does not lead to any binding of ligands to the HfO2 surface. On the other hand, we find that the addition of amines provides the basic environment in which carboxylic acids can dissociate and replace chloride. This results in stable, aggregate-free dispersions of HfO2 nanocrystals, sterically stabilized by carboxylate ligands. Moreover, titrations with deuterated carboxylic acid show that the charge on the carboxylate ligands is balanced by coadsorbed protons. Hence, opposite from the X-type/nonstoichiometric nanocrystals picture prevailing in literature, one should look at HfO2/carboxylate nanocrystals as systems where carboxylic acids are dissociatively adsorbed to bind to the nanocrystals. Similar results were obtained with ZrO2 NCs. Since proton accommodation on the surface is most likely due to the high Brønsted basicity of oxygen, our model could be a more general picture for the surface chemistry of metal oxide nanocrystals with important consequences on the chemistry of ligand exchange reactions.

Isotope-labelled folic acid derivatives

International Nuclear Information System (INIS)

Lewin, N.; Wong, E.T.

1976-01-01

The suggestion deals with the production of folic acid derivatives suitable as indicators or tracers for analyses of serum folates. These folic acid derivatives contain folic acid which is bound by one or both carboxyl groups to the amino nitrogen of compounds such as, e.g., tyramine, glycyl tyrosine, tyrosine, or the methyl ester of tyrosine. The derivative obtained can be substituted by a gamma emitter, e.g. the iodine isotope I 125. The radioactive derivative is used in the method for the competitive protein bonding to determine endogenic folates in the serum. (UWI) [de

1-Azaniumylcyclobutane-1-carboxylate monohydrate

Directory of Open Access Journals (Sweden)

Ray J. Butcher

2014-02-01

Full Text Available In the title compound, C5H9NO2·H2O, the amino acid is in the usual zwitterionic form involving the α-carboxylate group. The cyclobutane backbone of the amino acid is disordered over two conformations, with occupancies of 0.882 (7 and 0.118 (7. In the crystal, N—H...O and O—H...O hydrogen bonds link the zwitterions [with the water molecule involved as both acceptor (with the NH3+ and donor (through a single carboxylate O from two different aminocyclobutane carboxylate moities], resulting in a two-dimensional layered structure lying parallel to (100.

Production and Recovery of Pyruvic Acid: Recent Advances

Science.gov (United States)

Pal, Dharm; Keshav, Amit; Mazumdar, Bidyut; Kumar, Awanish; Uslu, Hasan

2017-12-01

Pyruvic acid is an important keto-carboxylic acid and can be manufactured by both chemical synthesis and biotechnological routes. In the present paper an overview of recent developments and challenges in various existing technique for the production and recovery of pyruvic acid from fermentation broth or from waste streams has been presented. The main obstacle in biotechnological production of pyruvic acid is development of suitable microorganism which can provide high yield and selectivity. On the other hand, technical limitation in recovery of pyruvic acid from fermentation broth is that, it could not be separated as other carboxylic acid in the form of salts by addition of alkali. Besides, pyruvic acid cannot be crystallized. Commercial separation by distillation is very expensive because pyruvic acid decomposes at higher temperature. It is also chemically reactive due to its peculiar molecular structure and has tendency to polymerize. Thus, at high concentration the various type of reaction leads to lower yield of the product, and hence, conventional methods are not favorable. Alternate separation technologies viable to both synthetic and biological routes are the current research areas. Latest techniques such as reactive extraction is new to the field of recovery of pyruvic acid. Recent development and future prospects in downstream processing of biochemically produced pyruvic acids has been discussed in this review article.

Adsorption of amino acids by fullerenes and fullerene nanowhiskers

Science.gov (United States)

Hashizume, Hideo; Hirata, Chika; Fujii, Kazuko; Miyazawa, Kun'ichi

2015-12-01

We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C60) and fullerene nanowhiskers (FNWs). C60 and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C60 or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C60 did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C60 and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C60 and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C60 and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C60. The theoretical simulations showed the bonding distance between C60 and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val changed a little by C60. In our study Try and Tyr were hardly adsorbed by C60 and FNWs. These amino acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides.

Heat capacity and thermodynamics of solid and liquid pyridine-3-carboxylic acid (nicotinic acid) over the temperature range 296 K to 531 K

International Nuclear Information System (INIS)

Joseph, Abhinav; Bernardes, Carlos E.S.; Minas da Piedade, Manuel E.

2012-01-01

Highlights: ► We determined the heat capacity of solid and liquid nicotinic acid by DSC. ► We determined Δ 357.8K 305.6K H m o (NA,crII) by Calvet microcalorimetry. ► We studied the thermodynamics of the cr II → cr I phase transition. ► We determined the Δ f G m o –T diagram of nicotinic acid for T = (296 to 531) K. - Abstract: The molar heat capacity of pyridine-3-carboxylic acid (nicotinic acid) for T = (296 to 531) K was investigated by differential scanning calorimetry (DSC) and Calvet-drop microcalorimetry. The measurements extended up to the liquid range and also covered the interval where a reversible and fast solid-solid (cr II → cr I) phase transition occurs. The molar enthalpies and entropies of that phase transition and of fusion were obtained as T trs = (455.0 ± 0.2) K, Δ trs H m o = (0.90 ± 0.10) kJ ⋅ mol −1 , Δ trs S m o = (1.98 ± 0.22) J ⋅ K −1 ⋅ mol −1 , T fus = (509.91 ± 0.04) K, Δ fus H m o = (28.2 ± 0.1) kJ ⋅ mol −1 , and Δ fus S m o = (55.30 ± 0.16) J ⋅ K −1 ⋅ mol −1 . By combining these experimental results with the previously reported Δ sub H m (NA,cr II) at T = 366.5 K, the corresponding entropy in the gaseous state calculated at the B3LYP/6-31+G(d,p) level of theory, and Δ f H m o (NA),cr II) at T = 298.15 K, it was possible to estimate the standard molar Gibbs energy of formation functions necessary for the construction of the Δ f G m ∘ vs. T diagram illustrating the enantiotropic nature of this system.

Structural transformations on N-acetylneuraminic acid

International Nuclear Information System (INIS)

Schmid, W.

1986-01-01

Structural transformations on N-Acetylneuraminic acid are of special interest because of the biological importance of this compound. Although many stereo- and regioselective variations (especially for pyranoid derivatives) have been reported, no detailed studies of the furanoid derivatives from N-Acetylneuramino-1, 4-lactone diethyl dithioacetal have been described hitherto. Therefore a series of derivatives of the Neu5Ac-lactone diethyl dithioacetal has been investigated by n.m.r. spectroscopic techniques. The complete assignment of the 1 H and 13 C resonances was achieved by relaxation time measurements, decoupling experiments and 2-D - shiftcorrelation spectroscopy. The influence of different substituents on the conformational behavior is also discussed. For the Tetra-O-Acetyl-N-acetylneuraminic acid-γ-lactone diethyl dithioacetal the conformation in solution could be determined. The observed data were explained by a zigzag conformation of the backbone as described for the acetylated mannose diethyl dithioacetal. The synthesis of the tetrazole-analogue of N-Acetylneuraminic acid is also described. This compound is of special biological interest because there is a similarity in acidity between the carboxyl-group and the tetrazole-function and the metabolic stability of the tetrazole function is enhanced in comparison with the carboxyl-group. Many of the biological functions of N-Acetylneuraminic acid are connected with the presence of the carboxyl-group. It was therefore interesting to transform this group to the bioisostere tetrazole-function to investigate the influence of the tetrazole-group of this compound on biological activity in the future. During the application of protective groups in the field of Neuraminic acid chemistry a new compound, an ortholactone-derivative of Neu5Ac, was discovered. It's structure is similar to an adamantanecage and the chemistry of such an orthoester function opens new possibilities for structural transformations on N

Preparation of carbon-14-labelled gallic acid

International Nuclear Information System (INIS)

Kozak, I.; Prochazka, M.

1977-01-01

Gallic acid labelled with 14 C was prepared for the needs of biological studies. A lithium derivative of trimethoxybenzene was treated with 14 CO 2 and then demethylated to yeld [carboxyl- 14 C]gallic acid. The preparation scheme and the individual steps of the synthesis are described in detail

Solvothermal synthesis of uranium(VI) phases with aromatic carboxylate ligands: A dinuclear complex with 4-hydroxybenzoic acid and a 3D framework with terephthalic acid

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yingjie, E-mail: yzx@ansto.gov.au [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Karatchevtseva, Inna [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Bhadbhade, Mohan [Mark Wainwright Analytical Centre, University of New South Wales, Kensington, NSW 2052 (Australia); Tran, Toan Trong; Aharonovich, Igor [School of Physics and Advanced Materials, University of Technology Sydney, Ultimo, NSW 2007 (Australia); Fanna, Daniel J.; Shepherd, Nicholas D. [School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 (Australia); Lu, Kim [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Li, Feng [School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 (Australia); Lumpkin, Gregory R. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

2016-02-15

With the coordination of dimethylformamide (DMF), two new uranium(VI) complexes with either 4-hydroxybenzoic acid (H{sub 2}phb) or terephthalic acid (H{sub 2}tph) have been synthesized under solvothermal conditions and structurally characterized. [(UO{sub 2}){sub 2}(Hphb){sub 2}(phb)(DMF)(H{sub 2}O){sub 3}]·4H{sub 2}O (1) has a dinuclear structure constructed with both pentagonal and hexagonal bipyramidal uranium polyhedra linked through a µ{sub 2}-bridging ligand via both chelating carboxylate arm and alcohol oxygen bonding, first observation of such a coordination mode of 4-hydroxybenzoate for 5 f ions. [(UO{sub 2})(tph)(DMF)] (2) has a three-dimensional (3D) framework built with pentagonal bipyramidal uranium polyhedra linked with µ{sub 4}-terephthalate ligands. The 3D channeled structure is facilitated by the unique carboxylate bonding with nearly linear C–O–U angles and the coordination of DMF molecules. The presence of phb ligands in different coordination modes, uranyl ions in diverse environments and DMF in complex 1, and tph ligand, DMF and uranyl ion in complex 2 has been confirmed by Raman spectroscopy. In addition, their thermal stability and photoluminescence properties have been investigated. - Graphical abstract: With the coordination of dimethylformamide, two new uranyl complexes with either 4-hydroxybenzoate or terephthalate have been synthesized under solvothermal conditions and structurally characterized. - Highlights: • Solvent facilitates the synthesis of two new uranium(VI) complexes. • A dinuclear complex with both penta- and hexagonal bipyramidal uranium polyhedral. • A unique µ{sub 2}-bridging mode of 4-hydroxybenzoate via alcohol oxygen for 5 f ions. • A 3D framework with uranium polyhedra and µ{sub 4}-terephthalate ligands. • Vibration modes and photoluminescence properties are reported.

2-[(1-Benzamido-2-methoxy-2-oxoethylamino]benzoic Acid

Directory of Open Access Journals (Sweden)

Alami Anouar

2013-01-01

Full Text Available The carboxylic α,α-diaminoester 2-[(1-benzamido-2-methoxy-2-oxoethyl amino]benzoic acid is obtained by N-alkylation of methyl α-azido glycinate N-benzoylated with 2-aminobenzoic acid.

Syntheses of {gamma}-aminobutyric-1-{sup 14}C and of {alpha}-aminoadipic-6-{sup 14}C acid from methoxy-3 chloropropyl-magnesium and marked carbon dioxide; Syntheses de l'acide {gamma}-aminobutyrique{sup 14}C-1 et de l'acide {alpha}-aminoadipique {sup 14}C-6 a partir de methoxy-3 chloropropylmagnesium et d'anhydride carbonique marque

Energy Technology Data Exchange (ETDEWEB)

Liem, Phung Nhu [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, Departement des radioelements, Service des molecules marquees

1967-04-01

Carbonation of {gamma}-methoxypropyl-magnesium chloride by CO{sub 2} gives {gamma}-methoxy-butyric carboxylic-{sup 14}C acid with a yield of about 95 per cent. When the latter is treated successively with anhydrous HBr and with diazomethane, methyl carboxylic {gamma}-bromobutyrate-{sup 14}C is formed. This in turn gives {gamma}-amino-butyric carboxylic-{sup 14}C acid with an overall yield of 66 per cent with respect to Ba{sup 14}CO{sub 3}, when it is condensed with potassium phthalimide and hydrolyzed by acid. By reacting methyl-{gamma}-bromobutyrate-{sup 14}C with the sodium derivative of ethyl cyanacetamido-acetate in ethanol, followed by an acid hydrolysis, {alpha}-aminoadipic-6-{sup 14}C acid is obtained with an overall yield of 46 per cent with respect to Ba{sup 14}CO{sub 3}. (author) [French] La carbonatation du chlorure de {gamma}-methoxypropylmagnesium par {sup 14}CO{sub 2} donne l'acide {gamma}-methoxybutyrique carboxyle {sup 14}C avec un rendement d'environ 95 pour cent. Ce dernier traite successivement par HBr anhydre et par le diazomethane conduit au {gamma}-bromobutyrate de methyle carboxyle {sup 14}C. Celui-ci condense avec le phtalimide de potassium suivi d'une hydrolyse acide fournit l'acide {gamma}-aminobutyrique carboxyle {sup 14}C avec un rendement global de 66 pour cent par rapport a Ba{sup 14}CO{sub 3}. L'action du {gamma}-bromobutyrate de methyle {sup 14}C sur le derive sode du cyanacetamidoacetate d'ethyle dans l'ethanol suivie d'hydrolyse acide donne l'acide {alpha}-aminoadipique {sup 14}C-6 avec un rendement global de 46 pour cent par rapport a Ba{sup 14}CO{sub 3}. (auteur)

Effects of Food on the Pharmacokinetics of Omega-3-Carboxylic Acids in Healthy Japanese Male Subjects: A Phase I, Randomized, Open-label, Three-period, Crossover Trial.

Science.gov (United States)

Shimada, Hitoshi; Nilsson, Catarina; Noda, Yoshinori; Kim, Hyosung; Lundström, Torbjörn; Yajima, Toshitaka

2017-09-01

Omega-3-carboxylic acids (OM3-CA) contain omega-3 free fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as carboxylic acids. Food intake is known to affect the bioavailability of ethyl ester fatty acid formulations. We conducted a phase I study to investigate the effects of the timing of OM3-CA administration relative to food intake on the pharmacokinetics of EPA and DHA. In this randomized, open-label, three-period crossover study, Japanese healthy male subjects were administered 4×1 g OM3-CA capsules with continued fasting, before a meal, or after a meal. All subjects fasted for ≥10 h prior to drug/meal administration. The primary objective was to examine the effect of meal timing on the pharmacokinetics of EPA and DHA after OM3-CA administration. The secondary objectives were to examine the safety and tolerability of OM3-CA. A total of 42 Japanese subjects was enrolled in the study. The baseline-adjusted maximum concentration and area under the concentration-time curve from 0 to 72 h for EPA, DHA, and EPA +DHA were lower in the fasting and before meal conditions than in the after meal condition. The maximum total EPA, total DHA, and total EPA+DHA concentrations were reached later when administered in fasting conditions than in fed conditions, indicating slower absorption in fasting conditions. Diarrhea was reported by five, six, and no subjects in the fasting, before meal, and after meal conditions, respectively. The timing of OM3-CA administration relative to food intake influences the systemic bioavailability of EPA and DHA in healthy Japanese male subjects. NCT02372344.

A library synthesis of 4-hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester derivatives as anti-tumor agents.

Science.gov (United States)

Hayakawa, Ichiro; Shioya, Rieko; Agatsuma, Toshinori; Furukawa, Hidehiko; Naruto, Shunji; Sugano, Yuichi

2004-09-06

As a result of a hit-to-lead program using a technique of solution-phase parallel synthesis, a highly potent (2,4-dimethoxyphenyl)-[6-(3-fluorophenyl)-4-hydroxy-3-methylbenzofuran-2-yl]methanone (15b) was synthesized as an optimized derivative of 4-hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester (1), which was discovered as a screening hit from small-molecule libraries and exhibited selective cytotoxicity against a tumorigenic cell line.

Synthesis of 1-Methyl-3-oxo-7-oxabicyclo[2.2.1]hept-5-ene-2-carboxylic Acid Methyl Ester

Directory of Open Access Journals (Sweden)

Gil Valdo José da Silva

2005-11-01

Full Text Available A simple and efficient method for the preparation of 1-methyl-3-oxo-7- oxabicyclo[2.2.1]hept-5-en-2-carboxylic acid methyl ester (1 is described. The first step is a highly regioselective Diels-Alder reaction between 2-methylfuran and methyl-3-bromo- propiolate. A remarkably difficult ketal hydrolysis reaction was effected by treatment with HCl, a simple reagent that was shown to be more efficient, in this case, than commonly used more elaborate methods.

Perfluorinated carboxylic and sulphonic acids in surface water media from the regions of Tibetan Plateau: Indirect evidence on photochemical degradation?

Science.gov (United States)

Yamazaki, Eriko; Falandysz, Jerzy; Taniyasu, Sachi; Hui, Ge; Jurkiewicz, Gabriela; Yamashita, Nobuyoshi; Yang, Yong-Liang; Lam, Paul K S

2016-01-01

Perfluorinated surfactants and repellents are synthetic substances that have found numerous industrial and customer applications. Due to their persistence, at least two groups of these substances-perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonic acids (PFSAs)-are diffused widely in the environment. It is hypothesized that the Tibetan Plateau, is one of few unique places on the Earth, due to its topography, specifically the vast space and high elevation above sea level, geographic location, climate, high solar radiation, lack of industry, little urbanization and general lack of significant direct sources of pollution. There it is believed possible to gain an insight into atmospheric fate (possible photochemical degradation of higher molecular mass and formation of lower molecular mass PFCAs and PFSAs) of PFASs under un-disturbed environmental conditions. Ultratrace analytical method for PFCAs and PFSAs and use of transportation and field blanks, laboratory blanks and isotopically labelled surrogates for recovery control has allowed the determination of nine perfluorinated carboxylic acids and six perfluorinated sulfonic acids at ultra-trace levels in water based samples from the alpine dimension regions of the Tibetan Plateau, the eastern slope of Minya Konka peak at the eastern edge of the Tibetan Plateau, and also from the city of Chengdu from the lowland of the Sichuan Province in China. The specific compositional pattern of PFCAs and PFSAs and low levels of pollution with those compounds were observed in the central region of the Tibetan Plateau and in the region adjacent to the peaks of Minya Konka in the Eastern Tibetan Plateau. The fingerprint of the compositional pattern of PFCAs and PFSAs in water samples in the central region of the Tibetan Plateau and in the alpine region adjacent to the peaks of Minya Konka in the Eastern Tibetan Plateau may be explained by the result of photochemical degradation with dealkylation of longer chain

Whole-body pharmacokinetics of HDAC inhibitor drugs, butyric acid, valproic acid and 4-phenylbutyric acid measured with carbon-11 labeled analogs by PET

International Nuclear Information System (INIS)

Kim, Sung Won; Hooker, Jacob M.; Otto, Nicola; Win, Khaing; Muench, Lisa; Shea, Colleen; Carter, Pauline; King, Payton; Reid, Alicia E.; Volkow, Nora D.; Fowler, Joanna S.

2013-01-01

The fatty acids, n-butyric acid (BA), 4-phenylbutyric acid (PBA) and valproic acid (VPA, 2-propylpentanoic acid) have been used for many years in the treatment of a variety of CNS and peripheral organ diseases including cancer. New information that these drugs alter epigenetic processes through their inhibition of histone deacetylases (HDACs) has renewed interest in their biodistribution and pharmacokinetics and the relationship of these properties to their therapeutic and side effect profiles. In order to determine the pharmacokinetics and biodistribution of these drugs in primates, we synthesized their carbon-11 labeled analogues and performed dynamic positron emission tomography (PET) in six female baboons over 90 min. The carbon-11 labeled carboxylic acids were prepared by using 11 CO 2 and the appropriate Grignard reagents. [ 11 C]BA was metabolized rapidly (only 20% of the total carbon-11 in plasma was parent compound at 5 min post injection) whereas for VPA and PBA 98% and 85% of the radioactivity were the unmetabolized compound at 30 min after their administration respectively. The brain uptake of all three carboxylic acids was very low ( VPA > PBA), which is consistent with the need for very high doses for therapeutic efficacy. Most of the radioactivity was excreted through the kidneys and accumulated in the bladder. However, the organ biodistribution between the drugs differed. [ 11 C]BA showed relatively high uptake in spleen and pancreas whereas [ 11 C]PBA showed high uptake in liver and heart. Notably, [ 11 C]VPA showed exceptionally high heart uptake possibly due to its involvement in lipid metabolism. The unique biodistribution of each of these drugs may be of relevance in understanding their therapeutic and side effect profile including their teratogenic effects

Equilibrium studies of ternary systems containing some selected transition metal ions, triazoles and aromatic carboxylic acids

Energy Technology Data Exchange (ETDEWEB)

Khalil, Mohamed Magdy; Radalla, Abd-Elatty; Qasem, Fatma; Khaled, Rehab [Beni-Suef University, Beni-Suef (Egypt)

2014-01-15

Solution equilibria of the binary and ternary complex systems of the divalent transition metal ions Cu{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Co{sup 2+} with 1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole (TRZSH), and 3-amino-1,2,4-triazole (TRZAM) and aromatic carboxylic acids (phthalic, anthranilic, salicylic, and 5-sulfosalicylic acid) have been studied pH-metrically at (25.0±0.1) .deg. C, and a constant ionic strength I=1x10{sup -1} mol L{sup -1} NaNO{sub 3} in an aqueous medium. The potentiometric titration curves show that binary and ternary complexes of these ligands are formed in solution. The stability constants of the different binary and ternary complexes formed were calculated on the basis of computer analysis of the titration data. The relative stability of the different ternary complex species is expressed in terms of Δ log K values, log X and R. S.% parameters. The effect of temperature of the medium on both the proton-ligand equilibria for TRZAM and phthalic acid and their metal-ligand equilibria with Cu{sup 2+}, Ni{sup 2+}, and Co{sup 2+} has been studied along with the corresponding thermodynamic parameters. The complexation behavior of ternary complexes is ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV-visible spectrophotometry.

Impact of the counterion on the solubility and physicochemical properties of salts of carboxylic acid drugs.

Science.gov (United States)

David, S E; Timmins, P; Conway, B R

2012-01-01

Salt formation is a widely used approach to improve the physicochemical and solid state properties of an active pharmaceutical ingredient. In order to better understand the relationships between the active drug, the selected counterion and the resultant salt form, crystalline salts were formed using four different carboxylic acid drugs and a closely related series of amine counterions. Thirty-six related crystalline salts were prepared, characterized and the relationship between solubility and dissolution behaviour and other properties of the salt and the counterion studied. Salts of four model acid drugs, gemfibrozil, flurbiprofen, ibuprofen and etodolac were prepared using the counterions butylamine, hexylamine, octylamine, benzylamine, cyclohexylamine, tert-butylamine, 2-amino-2-methylpropan-1-ol, 2-amino-2-methylpropan-1,3-diol and tris(hydroxymethyl)aminomethane. Salt formation was confirmed, the salts were characterized and their corresponding solubilities determined and rationalized with respect to the counterions' properties. The properties of the salt highly dependent on the nature of the counterion and, although there is considerable variation, some general conclusion can be drawn. For the alkyl amines series, increasing chain length leads to a reduction in solubility across all the acidic drugs studied and a reduction in melting point, thus contradicting simplistic relationships between solubility and melting point. Small, compact counterions consistently produce crystalline salts with high melting point accompanied with a modest improvement in solubility and the nature of hydrogen bonding between the ions has a major impact on the solubility.

Enhanced electrochemical response in oxidative differential pulse voltammetry of dopamine in the presence of ascorbic acid at carboxyl-terminated boron-doped diamond electrodes

Energy Technology Data Exchange (ETDEWEB)

Kondo, Takeshi [Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)], E-mail: t.kondo@ci.kagu.tus.ac.jp; Niwano, Yu; Tamura, Akira; Imai, Junichi [Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Honda, Kensuke [Department of Chemistry and Earth Sciences, Faculty of Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8521 (Japan); Einaga, Yasuaki [Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-0012 (Japan); Tryk, Donald A. [Fuel Cell Nanomaterials Center, University of Yamanashi, Takeda 4-3-11, Kofu, Yamanashi 400-8511 (Japan); Fujishima, Akira [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012 (Japan); Kawai, Takeshi [Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)

2009-03-01

The differential pulse voltammetric (DPV) peak for dopamine (DA) oxidation was found to be highly amplified by the addition of ascorbic acid (AA) when carboxyl-terminated boron-doped diamond (BDD) electrodes were used as the working electrode. The DP voltammogram for a solution containing DA and AA obtained using a 4-pentenoic acid-modified BDD (4PA-BDD) electrode showed well-separated oxidation peaks for DA and AA at 0.4 and 0.6 V vs. Ag/AgCl, respectively. In addition, as the DA concentration increased at constant AA concentration, a simultaneous increase in the DA peak current density and decrease in the AA peak current density were observed. The slope of the calibration curve for the [DA] range of 1-10 {mu}M in the presence of AA (500 {mu}M) was seven times larger than that obtained in the absence of AA. Such an enhancement was found to be more efficient at 4PA-BDD than at oxidized-BDD, partly due to simple electrostatic effects and partly due to suppression of the polymerization of DA oxidation products by the terminal carboxyl groups. The enhanced detection method using a carboxyl-terminated BDD electrode should be an effective analytical tool, especially for determining low concentrations of DA in the presence of high concentrations of AA.

Enhanced electrochemical response in oxidative differential pulse voltammetry of dopamine in the presence of ascorbic acid at carboxyl-terminated boron-doped diamond electrodes

International Nuclear Information System (INIS)

Kondo, Takeshi; Niwano, Yu; Tamura, Akira; Imai, Junichi; Honda, Kensuke; Einaga, Yasuaki; Tryk, Donald A.; Fujishima, Akira; Kawai, Takeshi

2009-01-01

The differential pulse voltammetric (DPV) peak for dopamine (DA) oxidation was found to be highly amplified by the addition of ascorbic acid (AA) when carboxyl-terminated boron-doped diamond (BDD) electrodes were used as the working electrode. The DP voltammogram for a solution containing DA and AA obtained using a 4-pentenoic acid-modified BDD (4PA-BDD) electrode showed well-separated oxidation peaks for DA and AA at 0.4 and 0.6 V vs. Ag/AgCl, respectively. In addition, as the DA concentration increased at constant AA concentration, a simultaneous increase in the DA peak current density and decrease in the AA peak current density were observed. The slope of the calibration curve for the [DA] range of 1-10 μM in the presence of AA (500 μM) was seven times larger than that obtained in the absence of AA. Such an enhancement was found to be more efficient at 4PA-BDD than at oxidized-BDD, partly due to simple electrostatic effects and partly due to suppression of the polymerization of DA oxidation products by the terminal carboxyl groups. The enhanced detection method using a carboxyl-terminated BDD electrode should be an effective analytical tool, especially for determining low concentrations of DA in the presence of high concentrations of AA

Spectroscopic and first principles investigation on 4-[(4-pyridinylmethylene)amino]-benzoic acid bearing pyridyl and carboxyl anchoring groups

Science.gov (United States)

Zhang, Lei; Wang, Qiaoyi

2018-03-01

We report a combined experimental and computational investigation on the structure and photophysics of 4-[(4-pyridinylmethylene)amino]-benzoic acid, a functional molecule bearing two anchoring groups for attachment onto a TiO2 surface and perovskite surface, for potential solar cell application. This molecule possesses interesting adsorption properties in perovskite solar cell because the pyridyl group serves as the Lewis base and targets Lewis acidic sites in the perovskite surface, while the carboxyl group targets TiO2 surface, improving the coupling between the perovskite surface and the TiO2 surface. The electronic structures of the molecule and its photochemistry are revealed by the UV-vis absorption spectra and the fluorescence spectra under visible light irradiation, which are combined with density functional theory (DFT) and time-dependent density functional theory (TDDFT) analysis. Considering the bi-anchoring groups and the conjugated π system embedded in the molecule, we anticipate it can molecular engineer the TiO2/perovskite interface in perovskite solar cell.

Uranium (IV) carboxylates - I

Energy Technology Data Exchange (ETDEWEB)

Satpathy, K C; Patnaik, A K [Sambalpur Univ. (India). Dept. of Chemistry

1975-11-01

A few uranium(IV) carboxylates with monochloro and trichloro acetic acid, glycine, malic, citric, adipic, o-toluic, anthranilic and salicylic acids have been prepared by photolytic methods. The I.R. spectra of these compounds are recorded and basing on the spectral data, structure of the compounds have been suggested.

Secondary metabolites from the sponge Tedania anhelans: Isolation and characterization of two novel pyrazole acids and other metabolites

Digital Repository Service at National Institute of Oceanography (India)

Parameswaran, P.S.; Naik, C.G.; Hegde, V.R.

Chemical investigation of the methanol extract of the sponge Tedania anhelans yielded the two unusual heteroaromatic acids, pyrazole-3(5)-carboxylic acid (2) and 4-methylpyrazole-3(5)-carboxylic acid (3), which are reported for the first time...

Adsorption of amino acids by fullerenes and fullerene nanowhiskers

International Nuclear Information System (INIS)

Hashizume, Hideo; Hirata, Chika; Fujii, Kazuko; Miyazawa, Kun’ichi

2015-01-01

We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C 60 ) and fullerene nanowhiskers (FNWs). C 60 and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C 60 or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C 60 did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C 60 and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C 60 and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C 60 and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C 60 . The theoretical simulations showed the bonding distance between C 60 and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val < Phe < Pro < Asp < Ala < Trp < Tyr < Arg < Leu. However, the simulation was not consistent with our experimental results. The adsorption of albumin (a protein) by C 60 showed the effect on the side chains of Try and Trp. The structure of albumin was changed a little by C 60 . In our study Try and Tyr were hardly adsorbed by C 60 and FNWs. These amino acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides. (paper)

Analysis of perfluorinated carboxylic acids in soils II: optimization of chromatography and extraction.

Science.gov (United States)

Washington, John W; Henderson, W Matthew; Ellington, J Jackson; Jenkins, Thomas M; Evans, John J

2008-02-15

With the objective of detecting and quantitating low concentrations of perfluorinated carboxylic acids (PFCAs), including perfluorooctanoic acid (PFOA), in soils, we compared the analytical suitability of liquid chromatography columns containing three different stationary phases, two different liquid chromatography-tandem mass spectrometry (LC/MS/MS) systems, and eight combinations of sample-extract pretreatments, extractions and cleanups on three test soils. For the columns and systems we tested, we achieved the greatest analytical sensitivity for PFCAs using a column with a C(18) stationary phase in a Waters LC/MS/MS. In this system we achieved an instrument detection limit for PFOA of 270 ag/microL, equating to about 14 fg of PFOA on-column. While an elementary acetonitrile/water extraction of soils recovers PFCAs effectively, natural soil organic matter also dissolved in the extracts commonly imparts significant noise that appears as broad, multi-nodal, asymmetric peaks that coelute with several PFCAs. The intensity and elution profile of this noise is highly variable among soils and it challenges detection of low concentrations of PFCAs by decreasing the signal-to-noise contrast. In an effort to decrease this background noise, we investigated several methods of pretreatment, extraction and cleanup, in a variety of combinations, that used alkaline and unbuffered water, acetonitrile, tetrabutylammonium hydrogen sulfate, methyl-tert-butyl ether, dispersed activated carbon and solid-phase extraction. For the combined objectives of complete recovery and minimization of background noise, we have chosen: (1) alkaline pretreatment; (2) extraction with acetonitrile/water; (3) evaporation to dryness; (4) reconstitution with tetrabutylammonium-hydrogen-sulfate ion-pairing solution; (5) ion-pair extraction to methyl-tert-butyl ether; (6) evaporation to dryness; (7) reconstitution with 60/40 acetonitrile/water (v/v); and (8) analysis by LC/MS/MS. Using this method, we

Evolution of the biosynthesis of the branched-chain amino acids

Science.gov (United States)

Keefe, Anthony D.; Lazcano, Antonio; Miller, Stanley L.

1995-01-01

The origins of the biosynthetic pathways for the branched-chain amino acids cannot be understood in terms of the backwards development of the present acetolactate pathway because it contains unstable intermediates. We propose that the first biosynthesis of the branched-chain amino acids was by the reductive carboxylation of short branched chain fatty acids giving keto acids which were then transaminated. Similar reaction sequences mediated by nonspecific enzymes would produce serine and threomine from the abundant prebiotic compounds glycolic and lactic acids. The aromatic amino acids may also have first been synthesized in this way, e.g. tryptophan from indole acetic acid. The next step would have been the biosynthesis of leucine from alpha-ketoisovalerc acid. The acetolactate pathway developed subsequently. The first version of the Krebs cycle, which was used for amino acid biosynthesis, would have been assembled by making use fo the reductive carboxylation and leucine biosynthesis enzymes, and completed with the development of a single new enzyme, succinate dehydrogenase. This evolutionary scheme suggests that there may be limitations to inferring the origins of metabolism by a simple back extrapolation of current pathways.

Determination of short chain carboxylic acids in vegetable oils and fats using ion exclusion chromatography electrospray ionization mass spectrometry.

Science.gov (United States)

Viidanoja, Jyrki

2015-02-27

A new method for quantification of short chain C1-C6 carboxylic acids in vegetable oils and fats by employing Liquid Chromatography Mass Spectrometry (LC-MS) has been developed. The method requires minor sample preparation and applies non-conventional Electrospray Ionization (ESI) liquid phase chemistry. Samples are first dissolved in chloroform and then extracted using water that has been spiked with stable isotope labeled internal standards that are used for signal normalization and absolute quantification of selected acids. The analytes are separated using Ion Exclusion Chromatography (IEC) and detected with Electrospray Ionization Mass Spectrometry (ESI-MS) as deprotonated molecules. Prior to ionization the eluent that contains hydrochloric acid is modified post-column to ensure good ionization efficiency of the analytes. The averaged within run precision and between run precision were generally lower than 8%. The accuracy was between 85 and 115% for most of the analytes. The Lower Limit of Quantification (LLOQ) ranged from 0.006 to 7mg/kg. It is shown that this method offers good selectivity in cases where UV detection fails to produce reliable results. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermophysical properties of carboxylic and amino acid buffers at subzero temperatures: relevance to frozen state stabilization.

Science.gov (United States)

Sundaramurthi, Prakash; Suryanarayanan, Raj

2011-06-02

Macromolecules and other thermolabile biologicals are often buffered and stored in frozen or dried (freeze-dried) state. Crystallization of buffer components in frozen aqueous solutions and the consequent pH shifts were studied in carboxylic (succinic, malic, citric, tartaric acid) and amino acid (glycine, histidine) buffers. Aqueous buffer solutions were cooled from room temperature (RT) to -25 °C and the pH of the solution was measured as a function of temperature. The thermal behavior of frozen solutions was investigated by differential scanning calorimetry (DSC), and the crystallized phases were identified by X-ray diffractometry (XRD). Based on the solubility of the neutral species of each buffer system over a range of temperatures, it was possible to estimate its degree of supersaturation at the subambient temperature of interest. This enabled us to predict its crystallization propensity in frozen systems. The experimental and the predicted rank orderings were in excellent agreement. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartrate systems, at initial pH pI. In the histidine buffer system, depending on the initial pH, either histidine or histidine HCl crystallized.

Glutamic acid as anticancer agent: An overview.

Science.gov (United States)

Dutta, Satyajit; Ray, Supratim; Nagarajan, K

2013-10-01

The objective of the article is to highlight various roles of glutamic acid like endogenic anticancer agent, conjugates to anticancer agents, and derivatives of glutamic acid as possible anticancer agents. Besides these emphases are given especially for two endogenous derivatives of glutamic acid such as glutamine and glutamate. Glutamine is a derivative of glutamic acid and is formed in the body from glutamic acid and ammonia in an energy requiring reaction catalyzed by glutamine synthase. It also possesses anticancer activity. So the transportation and metabolism of glutamine are also discussed for better understanding the role of glutamic acid. Glutamates are the carboxylate anions and salts of glutamic acid. Here the roles of various enzymes required for the metabolism of glutamates are also discussed.

Decarboxylation-based traceless linking with aroyl acrylic acids

DEFF Research Database (Denmark)

Nielsen, John

1998-01-01

beta-Keto carboxylic acids are known to decarboxylate readily. In our pursuit to synthesize beta-indolinyl propiophenones, we have exploited this chemistry as a mean of establishing a traceless handle. 2-Aroyl acrylic acids have been esterified to a trityl resin, after which Michael-type addition...

Extraction of some acids using aliphatic amines

International Nuclear Information System (INIS)

Matutano, L.

1964-06-01

Hydrochloric, nitric, sulphuric, perchloric, phosphoric, acetic and formic acids in aqueous solution (0.05 to 10 M) are extracted by amberlite LA2 and trilaurylamine in solution, 5 per cent by volume, in kerosene and xylene respectively. The extraction process consists of: neutralization of the amine salt; a 'molecular extraction', i.e. an extraction using an excess of acid with respect to the stoichiometry of the amine salt. According to the behaviour of the acid during the extraction, three groups may be distinguished: completely dissociated acids, carboxylic acids, phosphoric acid. This classification is also valid for the extraction of the water which occurs simultaneously with that of the acid. An extraction mechanism is put forward for formic acid and the formation constant of its amine salt is calculated. (author) [fr

Effects of aminoisobutyric acid on 1-aminocyclopropane-1-carboxylic acid uptake, ethylene production and content of ACC in water-stressed tomato plants

International Nuclear Information System (INIS)

Kalantari, Kh.M.; Bolourani, P.

2000-01-01

The effect of water stress on the regulation of ethylene biosynthesis has not yet clearly been established. Both the formation and utilization of aminocyclopropane-1-carboxylic acid, ACC, are considered to be major regulatory points in ethylene biosynthesis. There is evidence that ACC synthase is the key control enzyme in response to various stimuli associated with the induction of ethylene biosynthesis. It has been reported that aminoisobutyric acid, AIB, inhibits ethylene production in some plants and AIB may inhibit the conversion of ACC to ethylene. For this reason, the possibility of inhibition of ACC uptake in the presence of AIB was examined. It was observed that the rate of 14 C-ACC uptake decreased with an increase in the concentration of AIB in the solution. Calculating the percentage of ACC converted to ethylene on the basis of uptake shows that AIB inhibits the conversion of 14 C-ACC to ethylene and that this inhibition is increased with an increase in the concentration of AIB in the solution. This suggests that a portion of the inhibition of the conversion of ACC to ethylene in the presence of AIB is partly due to the competition for absorption. However, the ability of AIB to inhibit ethylene production in leaf tissue without an exogenous supply of ACC clearly indicates that AIB inhibits ethylene production. The present study was undertaken to elucidate the regulation of ethylene biosynthesis in water-stressed plants and the results are discussed

A Novel Strategy Towards the Asymmetric Synthesis of Orthogonally Funtionalised 2-N-Benzyl-N-α-methylbenzylamino- 5-carboxymethyl-cyclopentane-1-carboxylic acid.

Directory of Open Access Journals (Sweden)

Julio G. Urones

2004-04-01

Full Text Available The asymmetric synthesis of the orthogonally funtionalised compounds tert-butyl 2-N-benzyl-N-α-methylbenzylamino-5-methoxycarbonylmethylcyclopentane- 1-carboxylate and methyl 2-N-benzyl-N-α-methylbenzylamino-5–carboxymethylcyclo- pentane-1-carboxylate by a domino reaction of tert-butyl methyl (E,E-octa-2,6- diendioate with lithium N-α-methylbenzyl-N-benzylamide initiated by a Michael addition, subsequent 5-exo-trig intramolecular cyclisation and posterior selective hydrolysis with trifluoroacetic acid is reported.

Applications of Poly(indole-6-carboxylic acid-co-2,2′-bithiophene Films in High-Contrast Electrochromic Devices

Directory of Open Access Journals (Sweden)

Chung-Wen Kuo

2018-03-01

Full Text Available Two homopolymers (poly(indole-6-carboxylic acid (PInc and poly(2,2′-bithiophene (PbT and a copolymer (poly(indole-6-carboxylic acid-co-2,2′-bithiophene (P(Inc-co-bT are electrodeposited on ITO electrode surfaces via electrochemical method. Electrochemical and electrochromic properties of PInc, PbT, and P(Inc-co-bT films were characterized using cyclic voltammetry and in situ UV-Vis spectroscopy. The anodic P(Inc-co-bT film prepared using Inc./bT = 1/1 feed molar ratio shows high optical contrast (30% at 890 nm and coloring efficiency (112 cm2 C−1 at 890 nm. P(Inc-co-bT film revealed light yellow, yellowish green, and bluish grey in the neutral, intermediate, and oxidation states, respectively. Electrochromic devices (ECDs were constructed using PInc, PbT, or P(Inc-co-bT film as anodic layer and PEDOT-PSS as cathodic layer. P(Inc-co-bT/PMMA-PC-ACN-LiClO4/PEDOT-PSS ECD showed high ∆T (31% at 650 nm, and PInc/PMMA-PC-ACN-LiClO4/PEDOT-PSS ECD displayed high coloration efficiency (416.7 cm2 C−1 at 650 nm. The optical memory investigations of PInc/PMMA-PC-ACN-LiClO4/PEDOT-PSS, PbT/PMMA-PC-ACN-LiClO4/PEDOT-PSS, and P(Inc-co-bT/PMMA-PC-ACN-LiClO4/PEDOT-PSS ECDs exhibited that ECDs had adequate optical memory in bleaching and coloring states.

Cofactor balance by nicotinamide nucleotide transhydrogenase (NNT) coordinates reductive carboxylation and glucose catabolism in the tricarboxylic acid (TCA) cycle.

Science.gov (United States)

Gameiro, Paulo A; Laviolette, Laura A; Kelleher, Joanne K; Iliopoulos, Othon; Stephanopoulos, Gregory

2013-05-03

Cancer and proliferating cells exhibit an increased demand for glutamine-derived carbons to support anabolic processes. In addition, reductive carboxylation of α-ketoglutarate by isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) was recently shown to be a major source of citrate synthesis from glutamine. The role of NAD(P)H/NAD(P)(+) cofactors in coordinating glucose and glutamine utilization in the tricarboxylic acid (TCA) cycle is not well understood, with the source(s) of NADPH for the reductive carboxylation reaction remaining unexplored. Nicotinamide nucleotide transhydrogenase (NNT) is a mitochondrial enzyme that transfers reducing equivalents from NADH to NADPH. Here, we show that knockdown of NNT inhibits the contribution of glutamine to the TCA cycle and activates glucose catabolism in SkMel5 melanoma cells. The increase in glucose oxidation partially occurred through pyruvate carboxylase and rendered NNT knockdown cells more sensitive to glucose deprivation. Importantly, knocking down NNT inhibits reductive carboxylation in SkMel5 and 786-O renal carcinoma cells. Overexpression of NNT is sufficient to stimulate glutamine oxidation and reductive carboxylation, whereas it inhibits glucose catabolism in the TCA cycle. These observations are supported by an impairment of the NAD(P)H/NAD(P)(+) ratios. Our findings underscore the role of NNT in regulating central carbon metabolism via redox balance, calling for other mechanisms that coordinate substrate preference to maintain a functional TCA cycle.

Identification of Key Residues for Enzymatic Carboxylate Reduction

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Holly Stolterfoht

2018-02-01

Full Text Available Carboxylate reductases (CARs, E.C. 1.2.1.30 generate aldehydes from their corresponding carboxylic acid with high selectivity. Little is known about the structure of CARs and their catalytically important amino acid residues. The identification of key residues for carboxylate reduction provides a starting point to gain deeper understanding of enzymatic carboxylate reduction. A multiple sequence alignment of CARs with confirmed activity recently identified in our lab and from the literature revealed a fingerprint of conserved amino acids. We studied the function of conserved residues by multiple sequence alignments and mutational replacements of these residues. In this study, single-site alanine variants of Neurospora crassa CAR were investigated to determine the contribution of conserved residues to the function, expressability or stability of the enzyme. The effect of amino acid replacements was investigated by analyzing enzymatic activity of the variants in vivo and in vitro. Supported by molecular modeling, we interpreted that five of these residues are essential for catalytic activity, or substrate and co-substrate binding. We identified amino acid residues having significant impact on CAR activity. Replacement of His 237, Glu 433, Ser 595, Tyr 844, and Lys 848 by Ala abolish CAR activity, indicating their key role in acid reduction. These results may assist in the functional annotation of CAR coding genes in genomic databases. While some other conserved residues decreased activity or had no significant impact, four residues increased the specific activity of NcCAR variants when replaced by alanine. Finally, we showed that NcCAR wild-type and mutants efficiently reduce aliphatic acids.

Immune Modulation in Normal Human Peripheral Blood Mononuclear Cells (PBMCs) (Lymphocytes) in Response to Benzofuran-2-Carboxylic Acid Derivative KMEG during Spaceflight

Science.gov (United States)

Okoro, Elvis; Mann, Vivek; Ellis, Ivory; Mansoor, Elvedina; Olamigoke, Loretta; Marriott, Karla Sue; Denkins, Pamela; Williams, Willie; Sundaresan, Alamelu

2017-08-01

Microgravity and radiation exposure during space flight have been widely reported to induce the suppression of normal immune system function, and increase the risk of cancer development in humans. These findings pose a serious risk to manned space missions. Interestingly, recent studies have shown that benzofuran-2-carboxylic acid derivatives can inhibit the progression of some of these devastating effects on earth and in modeled microgravity. However, these studies had not assessed the impacts of benzofuran-2- carboxylic acid and its derivatives on global gene expression under spaceflight conditions. In this study, the ability of a specific benzofuran-2-carboxylic acid derivative (KMEG) to confer protection from radiation and restore normal immune function was investigated following exposure to space flight conditions on the ISS. Normal human peripheral blood mononuclear cells (lymphocytes) treated with 10 µ g/ml of KMEG together with untreated control samples were flown on Nanoracks hardware on Spacex-3 flight. The Samples were returned one month later and gene expression was analyzed. A 1g-ground control experiment was performed in parallel at the Kennedy spaceflight center. The first overall subtractive unrestricted analysis revealed 78 genes, which were differentially expressed in space flight KMEG, untreated lymphocytes as compared to the corresponding ground controls. However, in KMEG-treated space flight lymphocytes, there was an increased expression of a group of genes that mediate increased transcription, translation and innate immune system mediating functions of lymphocytes as compared to KMEG-untreated samples. Analysis of genes related to T cell proliferation in spaceflight KMEG-treated lymphocytes compared to 1g-ground KMEG- treated lymphocytes revealed six T cell proliferation and signaling genes to be significantly upregulated (p trafficking, promote early response, mediating C-myc related proliferation, promote antiapoptotic activity and protects

Radiation chemical synthesis of N-vinylpyrrolidone copolymers with undecylenic and oleic acids

International Nuclear Information System (INIS)

Ushakova, V.N.; Panarin, E.F.; Denisov, V.M.; Kol'tsov, A.I.; Persinen, A.A.

1988-01-01

Radiation copolymerization of N-vinylpyrrolidone with undecylenic and oleic acids is investigated. Irradiation was carried out at 320 and 300 K using γ-radiation with 0.23 and 0.04 Gy/s dose rate respectively. Polymer yield and copolimerization rate sufficiently depend on composition of initial mixture. Maximum molar concentration of carboxyl links in copolymer is 30 %. Statistic copolymer, which has no adjacent links of carboxylic acid, is formed. The relative reactivity of acids is equal to zero; reactivities of N-vinylpyrrolidone: 0.61< r<0.94 for undecylenic and 0.90 < r < 1.31 for oleic acid are calculated taking account of preterminal link effect

Acid monolayer functionalized iron oxide nanoparticle catalysts

Science.gov (United States)

Ikenberry, Myles

Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80° and starch at 130°, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide

Enhanced washing durability of hydrophobic coating on cellulose fabric using polycarboxylic acids

International Nuclear Information System (INIS)

Huang Wenqi; Xing Yanjun; Yu Yunyi; Shang Songmin; Dai Jinjin

2011-01-01

Nine polycarboxylic acids were used to improve washing durability of hydrophobic cellulose fabric finished by sol-gel method. By simultaneous forming ester-bridge between cellulose and silica layer by ester bond, polycarboxylic acids could anchor silica coating onto cellulose fabric to strengthen the adhesion of organic-inorganic hybrid coating. The wettability of treated fabrics was characterized by water contact angle, spray test and hydrostatic pressure test. The results showed that all investigated polycarboxylic acids could improve the durability. The polycarboxylic acid with proper distance between terminal carboxylic acid groups and number of carboxylic acid groups showed the highest durability. 1,2,3,4-butanetetracarboxylic acid (BTCA) led to the best durability of hydrophobic cellulose fabric with water contact angle of 137.6 o (recovery percentage of 94.2%) after 30 washing times. The effect of BTCA on durability was characterized by scanning electron microscopy. This study demonstrated that the surface treatment using polycarboxylic acids and mixed organosilanes is a promising alternative for achieving durable hydrophobic fabrics.

Carboxyl group reactivity in actin

Energy Technology Data Exchange (ETDEWEB)

Elzinga, M.

1986-01-01

While earlier work showed that the carboxyl groups of proteins could be quantitatively coupled to amino groups at pH 4.75 in the presence of EDC and a denaturing agent, the work presented here indicates that under milder conditions the modification of sidechain carboxyls is limited and somewhat specific. Most of the incorporated glycine ethyl ester (GEE) is apparently bound to five carboxyls. The total GEE incorporated was 3 to 4 moles/mole of protein as measured by an increase in Gly upon acid hydrolysis and amino acid analysis, as well as total radioactivity. 3.55 residues were found in peptides, 2.75 bound to residues 1 to 4, and 0.8 bound to Gly-100. 9 refs., 2 figs., 2 tabs.

Carboxyl group reactivity in actin

International Nuclear Information System (INIS)

Elzinga, M.

1986-01-01

While earlier work showed that the carboxyl groups of proteins could be quantitatively coupled to amino groups at pH 4.75 in the presence of EDC and a denaturing agent, the work presented here indicates that under milder conditions the modification of sidechain carboxyls is limited and somewhat specific. Most of the incorporated glycine ethyl ester (GEE) is apparently bound to five carboxyls. The total GEE incorporated was 3 to 4 moles/mole of protein as measured by an increase in Gly upon acid hydrolysis and amino acid analysis, as well as total radioactivity. 3.55 residues were found in peptides, 2.75 bound to residues 1 to 4, and 0.8 bound to Gly-100. 9 refs., 2 figs., 2 tabs

Synthesis of new derivatives of 1-(3-aminophenyl-4-benzoyl-5-phenyl-1H-pyrazole-3-carboxylic acid

Directory of Open Access Journals (Sweden)

RAHMI KASIMOGULLAR

2010-12-01

Full Text Available 1-(3-Aminophenyl-4-benzoyl-5-phenyl-1H-pyrazole-3-carboxylic acid (1 was synthesized according to the literature. 2-(3-Aminophenyl-2,6-dihydro-3,4-diphenyl-7H-pyrazolo[3,4-d]pyridazin-7-one (5 was obtained by the cyclocondensation reaction of 1 with hydrazine hydrate. New pyrazole derivatives of compounds 1 and 5 were synthesized by their reaction with β-diketones, β-ketoesters, β-naphthol, phenol and various other reagents. The structures of the synthesized compounds were characterized by 1H-NMR, 13C-NMR, IR and mass spectroscopy, as well as elemental analysis.

Body odour of monozygotic human twins: a common pattern of odorant carboxylic acids released by a bacterial aminoacylase from axilla secretions contributing to an inherited body odour type.

Science.gov (United States)

Kuhn, Fabian; Natsch, Andreas

2009-04-06

It is currently not fully established whether human individuals have a genetically determined, individual-specific body odour. Volatile carboxylic acids are a key class of known human body odorants. They are released from glutamine conjugates secreted in axillary skin by a specific Nalpha-acyl-glutamine-aminoacylase present in skin bacteria. Here, we report a quantitative investigation of these odorant acids in 12 pairs of monozygotic twins. Axilla secretions were sampled twice and treated with the Nalpha-acyl-glutamine-aminoacylase. The released acids were analysed as their methyl esters with comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry detection. The pattern of the analytes was compared with distance analysis. The distance was lowest between samples of the right and the left axilla taken on the same day from the same individual. It was clearly greater if the same subject was sampled on different days, but this intra-individual distance between samples was only slightly lower than the distance between samples taken from two monozygotic twins. A much greater distance was observed when comparing unrelated individuals. By applying cluster and principal component analyses, a clear clustering of samples taken from one pair of monozygotic twins was also confirmed. In conclusion, the specific pattern of precursors for volatile carboxylic acids is subject to a day-to-day variation, but there is a strong genetic contribution. Therefore, humans have a genetically determined body odour type that is at least partly composed of these odorant acids.

Acidogenesis driven by hydrogen partial pressure towards bioethanol production through fatty acids reduction

International Nuclear Information System (INIS)

Sarkar, Omprakash; Butti, Sai Kishore; Venkata Mohan, S.

2017-01-01

H 2 partial pressure drives the reduction of carboxylic acid (short chain fatty acids) formed as primary metabolites in acidogenic fermentation to form bioalcohols. Microbial catalysis under the influence of H 2 partial pressure was evaluated in comparison with a reactor operated at atmospheric pressure under identical conditions. Carboxylic acid reduction gets regulated selectively by the influence of elevated pressures and redox conditions, resulting in the formation of alcohols. The non-equilibrium of the intra and extracellular H 2 ions causes the anaerobic bacteria to alter their pathways as a function of interspecies H 2 transfer. Ethanol production was quantified, as acetic acid was the major carboxylic acid synthesised during acidogenesis. H 2 pressure influenced the electrochemical activity which was reflected in the distinct variation of the electron transfer rates and the catalytic activity of redox mediators (NAD + /NADH, flavoproteins and iron-sulphur clusters). The bioprocess depicted in this communication depicted a non-genetic regulation of product formation, understanding the acidogenic metabolism and alternate route for alcohol production. - Highlights: • H 2 partial pressure in HPR aided in the reduction of carboxylic acids to alcohols. • Production and consumption rate of VFAs were correlating with alcohol formation. • Metabolic shift was evident with bioelectrochical analysis. • NADH/NAD + ratio and H 2 partial pressure coupled in enhanced solventogenesis.

The Distant Double Bond Determines the Fate of the Carboxylic Group in the Dissociative Photoionization of Oleic Acid.

Science.gov (United States)

Heringa, Maarten F; Slowik, Jay G; Goldmann, Maximilian; Signorell, Ruth; Hemberger, Patrick; Bodi, Andras

2017-12-15

The valence threshold photoionization of oleic acid has been studied using synchrotron VUV radiation and imaging photoelectron photoion coincidence (iPEPICO) spectroscopy. An oleic acid aerosol beam was impacted on a copper thermodesorber, heated to 130 °C, to evaporate the particles quantitatively. Upon threshold photoionization, oleic acid produces the intact parent ion first, followed by dehydration at higher energies. Starting at ca. 10 eV, a large number of fragment ions slowly rise suggesting several fragmentation coordinates with quasi-degenerate activation energies. However, water loss is the dominant low-energy dissociation channel, and it is shown to be closely related to the unsaturated carbon chain. In the lowest-barrier process, one of the four allylic hydrogen atoms is transferred to the carboxyl group to form the leaving water molecule and a cyclic ketone fragment ion. A statistical model to analyze the breakdown diagram and measured rate constants yields a 0 K appearance energy of 9.77 eV, which can be compared with the density functional theory result of 9.19 eV. Alternative H-transfer steps yielding a terminal C=O group are ruled out based on energetics and kinetics arguments. Some of the previous photoionization mass spectrometric studies also reported 2 amu and 26 amu loss fragment ions, corresponding to hydrogen and acetylene loss. We could not identify such peaks in the mass spectrum of oleic acid. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous determination of dopamine, uric acid and nitrite using carboxylated graphene oxide/lanthanum modified electrode

International Nuclear Information System (INIS)

Ye, Fengying; Feng, Chenqi; Jiang, Jibo; Han, Sheng

2015-01-01

Highlights: • The carboxylated graphene oxide/lanthanum-modified glassy carbon electrode (GO-COOLa/GCE) was successfully utilized for the simultaneous detection and quantification of DA, UA and NO 2 − . • Combining the benefits of carboxylated graphene oxide and lanthanum, the modified sensor displayed large peak separations, long linear ranges and low detection limits for simultaneously detecting DA, UA and NO 2 − . • The GO-COOLa/GCE electrode showed well stability, good repeatability, rapid response, and high catalytic performance toward the oxidations of DA, UA and NO 2 − . - Abstract: A bare glassy carbon electrode (GCE) was reformed by carboxylated graphene oxide/lanthanum, and the modified electrode, called GO-COOLa/GCE, was fabricated for simultaneously detecting dopamine (DA), uric acid (UA) and nitrite (NO 2 − ) by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. Several factors which affected the electrocatalytic activity of the GO-COOLa/GCE electrode, such as the effect of pH, scan rate and concentration were studied. Due to the combination of carboxylated graphene oxide and lanthanum ions, the GO-COOLa/GCE sensor showed rapid response, excellent selectivity and high catalytic performance toward the electrooxidation of DA, UA and NO 2 − . In optimized conditions, two linear response ranges for determining DA were obtained over ranges of 0.01-1.96×10 2 μM and 1.96×10 2 -1.23×10 3 μM with detection limit of 0.018 μM (S/N = 3). And the responses of the GO-COOLa/GCE electrode for UA and NO 2 − were linear in the region of 1-1.53×10 3 μM and 1-2.75×10 3 μM with detection limits of 0.058 μM and 0.070 μM, respectively. Furthermore, this reformed electrode was successfully used to the detection of DA, UA and NO 2 − in real urine and serum samples, showing its promising application in the electroanalysis of real samples.

Characterization of acid tars

Energy Technology Data Exchange (ETDEWEB)

Leonard, Sunday A., E-mail: sunday.leonard@ucl.ac.uk [Department of Civil Environmental and Geomatic Engineering, University College London, Chadwick Building, Gower Street, London, WC1E 6BT (United Kingdom); Stegemann, Julia A. [Department of Civil Environmental and Geomatic Engineering, University College London, Chadwick Building, Gower Street, London, WC1E 6BT (United Kingdom); Roy, Amitava [J. Bennett Johnston, Sr., Centre for Advance Microstructures and Devices (CAMD), 6980 Jefferson Highway, Louisiana State University, Baton Rouge, LA, 70806 (United States)

2010-03-15

Acid tars from the processing of petroleum and petrochemicals using sulfuric acid were characterized by gas chromatography/mass spectrometry (GC/MS), inductively coupled plasma/optical emission spectrometry (ICP/OES), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectrometry, and scanning electron microscopy/energy dispersive X-ray (SEM/EDX) micro-analysis. Leaching of contaminants from the acid tars in 48 h batch tests with distilled water at a liquid-to-solid ratio 10:1 was also studied. GC/MS results show that the samples contained aliphatic hydrocarbons, cyclic hydrocarbons, up to 12 of the 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs), and numerous other organic groups, including organic acids (sulfonic acids, carboxylic acids and aromatic acids), phenyl, nitrile, amide, furans, thiophenes, pyrroles, and phthalates, many of which are toxic. Metals analysis shows that Pb was present in significant concentration. DSC results show different transition peaks in the studied samples, demonstrating their complexity and variability. FTIR analysis further confirmed the presence of the organic groups detected by GC/MS. The SEM/EDX micro-analysis results provided insight on the surface characteristics of the samples and show that contaminants distribution was heterogeneous. The results provide useful data on the composition, complexity, and variability of acid tars; information which hitherto have been scarce in public domain.

Characterization of acid tars

International Nuclear Information System (INIS)

Leonard, Sunday A.; Stegemann, Julia A.; Roy, Amitava

2010-01-01

Acid tars from the processing of petroleum and petrochemicals using sulfuric acid were characterized by gas chromatography/mass spectrometry (GC/MS), inductively coupled plasma/optical emission spectrometry (ICP/OES), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectrometry, and scanning electron microscopy/energy dispersive X-ray (SEM/EDX) micro-analysis. Leaching of contaminants from the acid tars in 48 h batch tests with distilled water at a liquid-to-solid ratio 10:1 was also studied. GC/MS results show that the samples contained aliphatic hydrocarbons, cyclic hydrocarbons, up to 12 of the 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs), and numerous other organic groups, including organic acids (sulfonic acids, carboxylic acids and aromatic acids), phenyl, nitrile, amide, furans, thiophenes, pyrroles, and phthalates, many of which are toxic. Metals analysis shows that Pb was present in significant concentration. DSC results show different transition peaks in the studied samples, demonstrating their complexity and variability. FTIR analysis further confirmed the presence of the organic groups detected by GC/MS. The SEM/EDX micro-analysis results provided insight on the surface characteristics of the samples and show that contaminants distribution was heterogeneous. The results provide useful data on the composition, complexity, and variability of acid tars; information which hitherto have been scarce in public domain.

Identification and quantification of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid glucuronide (THC-COOH-glu) in hair by ultra-performance liquid chromatography tandem mass spectrometry as a potential hair biomarker of cannabis use.

Science.gov (United States)

Pichini, Simona; Marchei, Emilia; Martello, Simona; Gottardi, Massimo; Pellegrini, Manuela; Svaizer, Fiorenza; Lotti, Andrea; Chiarotti, Marcello; Pacifici, Roberta

2015-04-01

We developed and validated an ultra-high-pressure liquid chromatography-tandem mass spectrometry method to identify and quantify 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid glucuronide in hair of cannabis consumers. After hair washing with methyl alcohol and diethyl ether and subsequent addition of amiodarone as internal standard hair samples were treated with 500 μl VMA-T M3 buffer reagent for 1 h at 100 °C. After cooling, 10 μl VMA-T M3 extract were injected into chromatographic system. Chromatographic separation was carried out on a reversed phase column using a linear gradient elution with two solvents: 5 mM ammonium formate pH 3.0 (solvent A) and 0.1% formic acid in acetonitrile (solvent B). The flow rate was kept constant at 0.4 ml/min during the analysis. The separated analytes were detected with a triple quadrupole mass spectrometer operated in multiple reaction monitoring mode via positive electrospray ionization. Linear calibration curves were obtained for 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid glucuronide with correlation coefficients (r(2)) of 0.99 and a limit of quantification of 0.25 pg/mg hair. Analytical recovery was between 79.6% and 100.7% and intra- and inter-assay imprecision and inaccuracy were always lower than 15%. Ultra-high-pressure liquid chromatography-tandem mass spectrometry analysis of 20 different hair samples of cannabis consumers disclosed the presence of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid glucuronide in the range of 0.5-8.6 pg/mg hair. These data provided a good start to consider 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid glucuronide as alternative hair biomarker of cannabis consumption. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Structural and thermodynamic study of rare earth(III) complexation by poly-hydroxylated carboxylic acids: synthesis of new extractants and outlook for the extraction of these cations; Etude structurale et thermodynamique de la complexation de lanthanides (III) par des acides carboxyliques polyhydroxyles: synthese de nouveaux extractants et perspectives pour l'extraction de ces cations

Energy Technology Data Exchange (ETDEWEB)

Aury, S

2002-12-15

The aim of this work is: to improve the knowledge on the binding sites of the poly-hydroxylated carboxylic acids with the trivalent lanthanide(III) ions by comparing them to gluconic acid (previously studied) and to molecules with different configuration and with a variable number of OH functions (threonic acid, glyceric acid, 2-hydroxy-butanoic acid, 3-hydroxy-butanoic acid). To find the best complexing agent among different acids (aldonic acids, aldaric acids, di-hydroxybenzoic acids) (determination of the set of complexes and their stability constants by potentiometry, NMR and UV-Visible spectroscopy). To synthesize hydrophobic monoamides from one lactone form of saccharic acid, to study their complexing power and their capacity to extract the trivalent lanthanide(III) ions. (author)

Acid-functionalized nanoparticles for biomass hydrolysis

Science.gov (United States)

Pena Duque, Leidy Eugenia

Cellulosic ethanol is a renewable source of energy. Lignocellulosic biomass is a complex material composed mainly of cellulose, hemicellulose, and lignin. Biomass pretreatment is a required step to make sugar polymers liable to hydrolysis. Mineral acids are commonly used for biomass pretreatment. Using acid catalysts that can be recovered and reused could make the process economically more attractive. The overall goal of this dissertation is the development of a recyclable nanocatalyst for the hydrolysis of biomass sugars. Cobalt iron oxide nanoparticles (CoFe2O4) were synthesized to provide a magnetic core that could be separated from reaction using a magnetic field and modified to carry acid functional groups. X-ray diffraction (XRD) confirmed the crystal structure was that of cobalt spinel ferrite. CoFe2O4 were covered with silica which served as linker for the acid functions. Silica-coated nanoparticles were functionalized with three different acid functions: perfluoropropyl-sulfonic acid, carboxylic acid, and propyl-sulfonic acid. Transmission electron microscope (TEM) images were analyzed to obtain particle size distributions of the nanoparticles. Total carbon, nitrogen, and sulfur were quantified using an elemental analyzer. Fourier transform infra-red spectra confirmed the presence of sulfonic and carboxylic acid functions and ion-exchange titrations accounted for the total amount of catalytic acid sites per nanoparticle mass. These nanoparticles were evaluated for their performance to hydrolyze the beta-1,4 glycosidic bond of the cellobiose molecule. Propyl-sulfonic (PS) and perfluoropropyl-sulfonic (PFS) acid functionalized nanoparticles catalyzed the hydrolysis of cellobiose significantly better than the control. PS and PFS were also evaluated for their capacity to solubilize wheat straw hemicelluloses and performed better than the control. Although PFS nanoparticles were stronger acid catalysts, the acid functions leached out of the nanoparticle during

Crystal structures of hibiscus acid and hibiscus acid dimethyl ester isolated from Hibiscus sabdariffa (Malvaceae)

OpenAIRE

Zheoat, Ahmed M.; Gray, Alexander I.; Igoli, John O.; Kennedy, Alan R.; Ferro, Valerie A.

2017-01-01

The biologically active title compounds have been isolated from Hibiscus sabdariffa plants, hibiscus acid as a dimethyl sulfoxide monosolvate [systematic name: (2S,3R)-3-hy?droxy-5-oxo-2,3,4,5-tetra?hydro?furan-2,3-di?carb?oxy?lic acid dimethyl sulfoxide monosolvate], C6H6O7?C2H6OS, (I), and hibiscus acid dimethyl ester [systematic name: dimethyl (2S,3R)-3-hy?droxy-5-oxo-2,3,4,5-tetra?hydro?furan-2,3-di?carboxyl?ate], C8H10O7, (II). Compound (I) forms a layered structure with alternating laye...

Radiolabeled derivatives of folic acid

International Nuclear Information System (INIS)

1980-01-01

Derivatives of folic acid are described, in which the α-carboxyl group is substituted with an amino compound having an aromatic or heterocyclic ring substituent which is capable of being radiolabelled. Particularly mentioned as a radiolabel is 125 I. (author)

Reciprocal effects of 5-(tetradecyloxy)-2-furoic acid on fatty acid oxidation.

Science.gov (United States)

Otto, D A; Chatzidakis, C; Kasziba, E; Cook, G A

1985-10-01

Under certain incubation conditions 5-(tetradecyloxy)-2-furoic acid (TOFA) stimulated the oxidation of palmitate by hepatocytes, as observed by others. A decrease in malonyl-CoA concentration accompanied the stimulation of oxidation. Under other conditions, however, TOFA inhibited fatty acid oxidation. The observed effects of TOFA depended on the TOFA and fatty acid concentrations, the cell concentration, the time of TOFA addition relative to the addition of fatty acid, and the nutritional state of the animal (fed or starved). The data indicate that only under limited incubation conditions may TOFA be used as an inhibitor of fatty acid synthesis without inhibition of fatty acid oxidation. When rat liver mitochondria were preincubated with TOFA, ketogenesis from palmitate was slightly inhibited (up to 20%) at TOFA concentrations that were less than that of CoA, but the inhibition became almost complete (up to 90%) when TOFA was greater than or equal to the CoA concentration. TOFA had only slight or no inhibitory effects on the oxidation of palmitoyl-CoA, palmitoyl(-)carnitine, or butyrate. Since TOFA can be converted to TOFyl-CoA, the data suggest that the inhibition of fatty acid oxidation from palmitate results from the decreased availability of CoA for extramitochondrial activation of fatty acids. These data, along with previous data of others, indicate that inhibition of fatty acid oxidation by CoA sequestration is a common mechanism of a group of carboxylic acid inhibitors. A general caution is appropriate with regard to the interpretation of results when using TOFA in studies of fatty acid oxidation.

Electrical properties of SAM-modified ITO surface using aromatic small molecules with double bond carboxylic acid groups for OLED applications

Energy Technology Data Exchange (ETDEWEB)

Can, Mustafa [Izmir Katip Celebi University, Faculty of Engineering, Department of Engineering Sciences, Çiğli, Izmir (Turkey); Havare, Ali Kemal [Toros University, Faculty of Engineering, Electric and Electronic Department, Mersin (Turkey); Aydın, Hasan; Yagmurcukardes, Nesli [Izmir Institute of Technology, Material Science and Engineering, Izmir (Turkey); Demic, Serafettin [Izmir Katip Celebi University, Faculty of Engineering, Department of Material Science and Engineering, Çiğli, Izmir (Turkey); Icli, Sıddık [Ege University, Solar Energy Institute, Izmir (Turkey); Okur, Salih, E-mail: salih.okur@ikc.edu.tr [Izmir Katip Celebi University, Faculty of Engineering, Department of Material Science and Engineering, Çiğli, Izmir (Turkey)

2014-09-30

Graphical abstract: - Highlights: • We report that the performance of OLED consist of aromatic small molecules with double bond carboxylic acid groups on ITO surface. • The OLED devices were tested in terms of electrical and optical characteristics. • The I–V results show that OLEDs with SAM-modified ITO surface have lower turn on voltages than OLED configurations without SAMs. - Abstract: 5-[(3-Methylphenyl)(phenyl)amino]isophthalic acid (5-MePIFA) and 5-(diphenyl)amino]isophthalic acid (5-DPIFA) organic molecules were synthesized to form self-assembled monolayer on indium tin oxide (ITO) anode to enhance hole transport from ITO to organic hole transport layers such as TPD. The modified surface was characterized by scanning tunneling microscopy (STM). The change in the surface potential was measured by Kelvin probe force microscopy (KPFM). Our Kelvin probe force microscopy (KPFM) measurements showed that the surface potentials increased more than 100 mV with reference to bare indium tin-oxide. The results show that the threshold voltage on OLEDs with modified ITO is lowered significantly compared to OLEDs with unmodified ITO. The hole mobility of TPD has been estimated using space–charge-limited current measurements (SCLC)

Electrical properties of SAM-modified ITO surface using aromatic small molecules with double bond carboxylic acid groups for OLED applications

International Nuclear Information System (INIS)

Can, Mustafa; Havare, Ali Kemal; Aydın, Hasan; Yagmurcukardes, Nesli; Demic, Serafettin; Icli, Sıddık; Okur, Salih

2014-01-01

Graphical abstract: - Highlights: • We report that the performance of OLED consist of aromatic small molecules with double bond carboxylic acid groups on ITO surface. • The OLED devices were tested in terms of electrical and optical characteristics. • The I–V results show that OLEDs with SAM-modified ITO surface have lower turn on voltages than OLED configurations without SAMs. - Abstract: 5-[(3-Methylphenyl)(phenyl)amino]isophthalic acid (5-MePIFA) and 5-(diphenyl)amino]isophthalic acid (5-DPIFA) organic molecules were synthesized to form self-assembled monolayer on indium tin oxide (ITO) anode to enhance hole transport from ITO to organic hole transport layers such as TPD. The modified surface was characterized by scanning tunneling microscopy (STM). The change in the surface potential was measured by Kelvin probe force microscopy (KPFM). Our Kelvin probe force microscopy (KPFM) measurements showed that the surface potentials increased more than 100 mV with reference to bare indium tin-oxide. The results show that the threshold voltage on OLEDs with modified ITO is lowered significantly compared to OLEDs with unmodified ITO. The hole mobility of TPD has been estimated using space–charge-limited current measurements (SCLC)

Acid-base chemistry of white wine: analytical characterisation and chemical modelling.

Science.gov (United States)

Prenesti, Enrico; Berto, Silvia; Toso, Simona; Daniele, Pier Giuseppe

2012-01-01

A chemical model of the acid-base properties is optimized for each white wine under study, together with the calculation of their ionic strength, taking into account the contributions of all significant ionic species (strong electrolytes and weak one sensitive to the chemical equilibria). Coupling the HPLC-IEC and HPLC-RP methods, we are able to quantify up to 12 carboxylic acids, the most relevant substances responsible of the acid-base equilibria of wine. The analytical concentration of carboxylic acids and of other acid-base active substances was used as input, with the total acidity, for the chemical modelling step of the study based on the contemporary treatment of overlapped protonation equilibria. New protonation constants were refined (L-lactic and succinic acids) with respect to our previous investigation on red wines. Attention was paid for mixed solvent (ethanol-water mixture), ionic strength, and temperature to ensure a thermodynamic level to the study. Validation of the chemical model optimized is achieved by way of conductometric measurements and using a synthetic "wine" especially adapted for testing.

Acid-Base Chemistry of White Wine: Analytical Characterisation and Chemical Modelling

Directory of Open Access Journals (Sweden)

Enrico Prenesti

2012-01-01

Full Text Available A chemical model of the acid-base properties is optimized for each white wine under study, together with the calculation of their ionic strength, taking into account the contributions of all significant ionic species (strong electrolytes and weak one sensitive to the chemical equilibria. Coupling the HPLC-IEC and HPLC-RP methods, we are able to quantify up to 12 carboxylic acids, the most relevant substances responsible of the acid-base equilibria of wine. The analytical concentration of carboxylic acids and of other acid-base active substances was used as input, with the total acidity, for the chemical modelling step of the study based on the contemporary treatment of overlapped protonation equilibria. New protonation constants were refined (L-lactic and succinic acids with respect to our previous investigation on red wines. Attention was paid for mixed solvent (ethanol-water mixture, ionic strength, and temperature to ensure a thermodynamic level to the study. Validation of the chemical model optimized is achieved by way of conductometric measurements and using a synthetic “wine” especially adapted for testing.

Acid-Base Chemistry of White Wine: Analytical Characterisation and Chemical Modelling

Science.gov (United States)

Prenesti, Enrico; Berto, Silvia; Toso, Simona; Daniele, Pier Giuseppe

2012-01-01

A chemical model of the acid-base properties is optimized for each white wine under study, together with the calculation of their ionic strength, taking into account the contributions of all significant ionic species (strong electrolytes and weak one sensitive to the chemical equilibria). Coupling the HPLC-IEC and HPLC-RP methods, we are able to quantify up to 12 carboxylic acids, the most relevant substances responsible of the acid-base equilibria of wine. The analytical concentration of carboxylic acids and of other acid-base active substances was used as input, with the total acidity, for the chemical modelling step of the study based on the contemporary treatment of overlapped protonation equilibria. New protonation constants were refined (L-lactic and succinic acids) with respect to our previous investigation on red wines. Attention was paid for mixed solvent (ethanol-water mixture), ionic strength, and temperature to ensure a thermodynamic level to the study. Validation of the chemical model optimized is achieved by way of conductometric measurements and using a synthetic “wine” especially adapted for testing. PMID:22566762

One-step hydrothermal synthesis of carboxyl-functionalized upconversion phosphors for bioapplications.

Science.gov (United States)

Yang, Jianping; Shen, Dengke; Li, Xiaomin; Li, Wei; Fang, Yin; Wei, Yong; Yao, Chi; Tu, Bo; Zhang, Fan; Zhao, Dongyuan

2012-10-22

In this paper, we report a facile one-step hydrothermal method to synthesize phase-, size-, and shape-controlled carboxyl-functionalized rare-earth fluorescence upconversion phosphors by using a small-molecule binary acid, such as malonic acid, oxalic acid, succinic acid, or tartaric acid as capping agent. The crystals, from nano- to microstructures with diverse shapes that include nanospheres, microrods, hexagonal prisms, microtubes, microdisks, polygonal columns, and hexagonal tablets, can be obtained with different reaction times, reaction temperatures, molar ratios of capping agent to sodium hydroxide, and by varying the binary acids. Fourier transform infrared, thermogravimetric analysis, and upconversion luminescence spectra measurements indicate that the synthesized NaYF(4):Yb/Er products with hydrophilic carboxyl-functionalized surface offer efficient upconversion luminescent performance. Furthermore, the antibody/secondary antibody conjugation can be realized by the carboxyl-functionalized surfaces of the upconversion phosphors, thus indicating the potential bioapplications of these kinds of materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Predicted Gas-Phase and Liquid-Phase Acidities of Carborane Carboxylic and Dicarboxylic Acids

Czech Academy of Sciences Publication Activity Database

Oliva-Enrich, J. M.; Humbel, S.; Santaballa, J.A.; Alkorta, I.; Notario, R.; Dávalos, J. Z.; Canle-L., M.; Bernhardt, E.; Holub, Josef; Hnyk, Drahomír

2018-01-01

Roč. 3, č. 16 (2018), s. 4344-4353 ISSN 2365-6549 Institutional support: RVO:61388980 Keywords : Acidity * Carboranes * Computational Chemistry * Delocalization Energy * Electronic Structure Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry

An irresolute linker: separation, and structural and spectroscopic characterization of the two linkage isomers of a Ru(ii)-(2-(2'-pyridyl)pyrimidine-4-carboxylic acid) complex.

Science.gov (United States)

Iengo, E; Demitri, N; Balducci, G; Alessio, E

2014-08-28

For the first time the two linkage isomers of a Ru(ii) complex with 2-(2'-pyridyl)pyrimidine-4-carboxylic acid (cppH) - that form in comparable amounts - have been fully characterized individually. The X-ray structure of each isomer is related to its NMR spectrum in solution.

Systems metabolic engineering design: fatty acid production as an emerging case study.

Science.gov (United States)

Tee, Ting Wei; Chowdhury, Anupam; Maranas, Costas D; Shanks, Jacqueline V

2014-05-01

Increasing demand for petroleum has stimulated industry to develop sustainable production of chemicals and biofuels using microbial cell factories. Fatty acids of chain lengths from C6 to C16 are propitious intermediates for the catalytic synthesis of industrial chemicals and diesel-like biofuels. The abundance of genetic information available for Escherichia coli and specifically, fatty acid metabolism in E. coli, supports this bacterium as a promising host for engineering a biocatalyst for the microbial production of fatty acids. Recent successes rooted in different features of systems metabolic engineering in the strain design of high-yielding medium chain fatty acid producing E. coli strains provide an emerging case study of design methods for effective strain design. Classical metabolic engineering and synthetic biology approaches enabled different and distinct design paths towards a high-yielding strain. Here we highlight a rational strain design process in systems biology, an integrated computational and experimental approach for carboxylic acid production, as an alternative method. Additional challenges inherent in achieving an optimal strain for commercialization of medium chain-length fatty acids will likely require a collection of strategies from systems metabolic engineering. Not only will the continued advancement in systems metabolic engineering result in these highly productive strains more quickly, this knowledge will extend more rapidly the carboxylic acid platform to the microbial production of carboxylic acids with alternate chain-lengths and functionalities. © 2014 Wiley Periodicals, Inc.

Simultaneous determination of carbohydrates, carboxylic acids, alcohols, and metals in foods by high-performance liquid chromatography inductively coupled plasma atomic emission spectrometry.

Science.gov (United States)

Paredes, Eduardo; Maestre, Salvador E; Prats, Soledad; Todolí, José L

2006-10-01

The applicability of the HPLC-ICP-AES coupling for the simultaneous determination of carbohydrates, carboxylic acids, alcohols, and metals in a single chromatographic run has been demonstrated in the present work. Five saccharides, glucose, fructose, sucrose, sorbitol, and lactose; five carboxylic acids, citric, tartaric, malic, lactic, and acetic; and three alcohols, glycerol, ethanol, and methanol, have been determined. A H+ cation exchange column has been used to separate these compounds. The chromatograms have been obtained by monitoring the carbon emission signal at 193.09 nm. The results obtained by HPLC-ICP-AES have been compared against those found with conventional detection systems (i.e., refractive index, UV, and photodyode array detectors). The HPLC-ICP-AES method has shown the following features: (i) organic compounds and metals can be simultaneously determined; (ii) the detection method is universal; (iii) for nonvolatile organic compounds, a complete calibration line can be obtained from a single injection; and (iv) it provides absolute limits of detection similar to or lower than those found with conventional detection systems (i.e., on the order of several tens of nanograms of organic compound). The methodology has been validated through the analysis of food samples such as juices, isotonic beverages, wines, and a certified nonfat milk powder sample.

Hydrophilic carboxylic acids and iridoid glycosides in the juice of American and European cranberries (Vaccinium macrocarpon and V. oxycoccos), lingonberries (V. vitis-idaea), and blueberries (V. myrtillus)

DEFF Research Database (Denmark)

Jensen, Heidi Dorthe; Krogfelt, Karen A; Cornett, Claus

2002-01-01

iridoid glucosides were shown to be monotropein and 6,7-dihydromonotropein by MS and NMR spectroscopy. A fast reversed-phase HPLC method for quantification of the hydrophilic carboxylic acids was developed and used for analyses of cranberry, lingonberry, and blueberry juices. The level of hydrophilic...

Cofactor Balance by Nicotinamide Nucleotide Transhydrogenase (NNT) Coordinates Reductive Carboxylation and Glucose Catabolism in the Tricarboxylic Acid (TCA) Cycle*♦

Science.gov (United States)

Gameiro, Paulo A.; Laviolette, Laura A.; Kelleher, Joanne K.; Iliopoulos, Othon; Stephanopoulos, Gregory

2013-01-01

Cancer and proliferating cells exhibit an increased demand for glutamine-derived carbons to support anabolic processes. In addition, reductive carboxylation of α-ketoglutarate by isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) was recently shown to be a major source of citrate synthesis from glutamine. The role of NAD(P)H/NAD(P)+ cofactors in coordinating glucose and glutamine utilization in the tricarboxylic acid (TCA) cycle is not well understood, with the source(s) of NADPH for the reductive carboxylation reaction remaining unexplored. Nicotinamide nucleotide transhydrogenase (NNT) is a mitochondrial enzyme that transfers reducing equivalents from NADH to NADPH. Here, we show that knockdown of NNT inhibits the contribution of glutamine to the TCA cycle and activates glucose catabolism in SkMel5 melanoma cells. The increase in glucose oxidation partially occurred through pyruvate carboxylase and rendered NNT knockdown cells more sensitive to glucose deprivation. Importantly, knocking down NNT inhibits reductive carboxylation in SkMel5 and 786-O renal carcinoma cells. Overexpression of NNT is sufficient to stimulate glutamine oxidation and reductive carboxylation, whereas it inhibits glucose catabolism in the TCA cycle. These observations are supported by an impairment of the NAD(P)H/NAD(P)+ ratios. Our findings underscore the role of NNT in regulating central carbon metabolism via redox balance, calling for other mechanisms that coordinate substrate preference to maintain a functional TCA cycle. PMID:23504317

Synthesis of omega-hydroxy carboxylic acids and alpha,omega-dimethyl ketones using alpha,omega-diols as alkylating agents.

Science.gov (United States)

Iuchi, Yosuke; Hyotanishi, Megumi; Miller, Brittany E; Maeda, Kensaku; Obora, Yasushi; Ishii, Yasutaka

2010-03-05

Synthesis of omega-hydroxy carboxylic acids and alpha,omega-dimethyl diketones was successfully achieved by using alpha,omega-diols as alkylating agents under the influence of an iridium catalyst. For example, the alkylation of butyl cyanoacetate with 1,13-tridecanediol in the presence of [IrCl(cod)](2) or [IrCl(coe)(2)](2) gave rise to butyl 2-cyano-15-hydroxypentadecanoate in good yield which is easily converted to cyclopentadecanolide (CPDL). In addition, the alkylation of acetone with 1,10-decanediol in the presence of [IrCl(cod)](2) and KOH resulted in an important muscone precursor, 2,15-hexadecanedione (HDDO), in good yield.

Experimental and theoretical elucidation of structural and antioxidant properties of vanillylmandelic acid and its carboxylate anion

Science.gov (United States)

Dimić, Dušan; Milenković, Dejan; Ilić, Jelica; Šmit, Biljana; Amić, Ana; Marković, Zoran; Dimitrić Marković, Jasmina

2018-06-01

Vanillylmandelic acid (VMA), an important metabolite of catecholamines that is routinely screened as tumor marker, was investigated by the various spectroscopic techniques (IR, Raman, UV-Vis, antioxidant decolorization assay and NMR). Structures optimized by the employment of five common functionals (M05-2X, M06-2X, B3LYP, CAM-B3LYP, B3LYP-D3) were compared with the crystallographic data. The M05-2X functional reproduced the most reliable experimental bond lengths and angles (correlation coefficient >0.999). The importance of intramolecular hydrogen bonds for structural stability was discussed and quantified by the NBO analysis. The most prominent bands in vibrational spectrum were analyzed and compared to the experimental data. The positions of the carbon and hydrogen atoms in NMR spectra were well reproduced. The differences in UV-Vis spectrum were investigated by adding the explicit solvent and by performing NBO and QTAIM analyses. The discrepancy in the two spectra of about 50 nm could be explained by the solvent effect on carboxyl group. The most probable antioxidant activity mechanism was discussed for VMA and its carboxylate anion. The Molecular Docking study with the C - reactive protein additionally proved that variety of functional groups present in VMA and its anion allowed strong hydrogen and hydrophobic interactions.

Microbial Propionic Acid Production

Directory of Open Access Journals (Sweden)

R. Axayacatl Gonzalez-Garcia

2017-05-01

Full Text Available Propionic acid (propionate is a commercially valuable carboxylic acid produced through microbial fermentation. Propionic acid is mainly used in the food industry but has recently found applications in the cosmetic, plastics and pharmaceutical industries. Propionate can be produced via various metabolic pathways, which can be classified into three major groups: fermentative pathways, biosynthetic pathways, and amino acid catabolic pathways. The current review provides an in-depth description of the major metabolic routes for propionate production from an energy optimization perspective. Biological propionate production is limited by high downstream purification costs which can be addressed if the target yield, productivity and titre can be achieved. Genome shuffling combined with high throughput omics and metabolic engineering is providing new opportunities, and biological propionate production is likely to enter the market in the not so distant future. In order to realise the full potential of metabolic engineering and heterologous expression, however, a greater understanding of metabolic capabilities of the native producers, the fittest producers, is required.

Crystallographic and spectroscopic characterization of (R-O-acetylmandelic acid

Directory of Open Access Journals (Sweden)

Cady Cirbes

2016-07-01

Full Text Available The title compound [systematic name: (R-(−-2-acetoxy-2-phenylacetic acid], C10H10O4, is a resolved chiral ester derivative of mandelic acid. The compound contains an acetate group and a carboxylic acid group, which engage in intermolecular hydrogen bonding, forming chains extending parallel to [001] with a short donor–acceptor hydrogen-bonding distance of 2.676 (2 Å.

Preliminary assessment of developmental toxicity of Perfluorinated Phosphonic Acid in mice

Science.gov (United States)

Perfluorinated phosphonic acids (PFPAs) are a third member of the perfluoroalkyl acid (PFAA) family, and are structurally similar to the perfluoroalkyl sulfonates and perfluoroalkyl carboxylates. These emerging chemicals have recently been detected in the environment, particularl...

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

Science.gov (United States)

Sych, N. V.; Trofymenko, S. I.; Poddubnaya, O. I.; Tsyba, M. M.; Sapsay, V. I.; Klymchuk, D. O.; Puziy, A. M.

2012-11-01

Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (SBET = 2081 m2/g, Vtot = 1.1 cm3/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

NMR and spectroscopic studies on uranyl ion interaction with aspartic acid and asparagine

International Nuclear Information System (INIS)

Wieczorek, H.; Kozlowski, H.

1980-01-01

The carboxyl groups of peptides or proteins are quite effective in the binding of UO 2 +2 ion and as the first step in studies in that field aspartic acid has been chosen as the bi-carboxylic ligand. The data for UO 2 +2 -asparagine system are also presented in this communication as they complete the results obtained for the UO 2 +2 -aspartic acid system. (author)

Mass spectrometric studies of stable isotope-labelled carboxylic acid derivatives

International Nuclear Information System (INIS)

Andersson, B.Aa.; Dinger, F.; Dinh-Nguyen, N.

1975-01-01

Low resolution mass spectra of deuterium and carbon-13 labelled fatty acid pyrrolidides are discussed. The simple fragmentation pattern of pyrrolidides makes them superior to other derivatives, regarding location of isotopes. Deuteriation of ethylenic fatty acid pyrrolidides therefore seems to be an improved method to locate carbon-carbon double bonds by mass spectrometry. (author)

Fe(II) and Co (II) complexes of (4-(4-bromophenyl)-[2,2'-bipyridine]-6-carboxylic acid) synthesis, characterization and electrochromic studies

International Nuclear Information System (INIS)

Saba, A.; Maqsood, Z.T.; Wasim, A.A.; Basha, F.Z.

2017-01-01

In this study novel complexes of substituted bipyridine (4-(4-bromophenyl)-[2,2'-bipyridine]-6-carboxylic acid) with Fe/sup +2/ and Co/sup +2/ were synthesized and characterized by different physical, analytical and spectral techniques which includes /sup 1/ H-NMR, MALDI-MS, FTIR, UV-VIS Spectrophotometry, CHN analysis and conductometry. Mole ratio method revealed that both complexes satisfied ML2 stoichiometry. Other characterization studies showed that substituted bipyridine acted as a tridentate ligand, with two pyridine N and one carboxylic O atom as binding sites per ligand molecule. The complexes were found octahedral, neutral and possessed fairly high molar absorptivities in visible region. Electrochromic studies revealed that Fe (II) complex had relatively good electrochromic properties with a reversible color change from blue to pale yellow. Co (II) complex, however, did not show significant electrochromic properties in the visible region. (author)

Discovery of a New Class of Ionotropic Glutamate Receptor Antagonists by the Rational Design of (2S,3R)-3-(3-Carboxyphenyl)-pyrrolidine-2-carboxylic Acid

DEFF Research Database (Denmark)

Larsen, Ann Møller; Venskutonyte, Raminta; Valadés, Elena Antón

2011-01-01

The kainic acid (KA) receptors belong to the class of glutamate (Glu) receptors in the brain and constitute a promising target for the treatment of neurological and/ or psychiatric diseases such as schizophrenia, major depression, and epilepsy. Five KA subtypes have been identified and named GluK1......-5. In this article, we present the discovery of (2S,3R)-3-(3-carboxyphenyl)-pyrrolidine-2-carboxylic acid (1) based on a rational design process. Target compound 1 was synthesized by a stereoselective strategy in 10 steps from commercially available starting materials. Binding affinities of 1 at native ionotropic...

A comparison of properties between carboxylated acrylic rubbers prepared by γ-ray irradiation and chemical method