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Showing papers on "Benzoic acid published in 1996"


Journal ArticleDOI
TL;DR: In this article, a new preparation for potassium ferrate (VI) (K(2)FeO(4)) was devised for oxidizing organic substrates in nonaqueous media.
Abstract: A new, efficient preparation has been devised for potassium ferrate(VI) (K(2)FeO(4)). The ability of this high-valent iron salt for oxidizing organic substrates in nonaqueous media was studied. Using benzyl alcohol as a model, the catalytic activity of a wide range of microporous adsorbents was ascertained. Among numerous solid supports of the aluminosilicate type, the K10 montmorillonite clay was found to be best at achieving quantitative formation of benzaldehyde, without any overoxidation to benzoic acid. The roles of the various parameters (reaction time and temperature, nature of the solvent, method of preparation of the solid reagent) were investigated. The evidence points to a polar reaction mechanism. The ensuing procedure was applied successfully, at room temperature, to oxidation of a series of alcohols to aldehydes and ketones, to oxidative coupling of thiols to disulfides, and to oxidation of nitrogen derivatives. At 75 degrees C, the reagent has the capability of oxidizing both activated and nonactivated hydrocarbons. Toluene is turned into benzyl alcohol (and benzaldehyde). Cycloalkanes are also oxidized, in significant (30-40%) yields, to the respective cycloalkanols (and cycloalkanones). Thus, potassium ferrate, used in conjunction with an appropriate heterogeneous catalyst, is a strong and environmentally friendly oxidant.

286 citations


Journal ArticleDOI
TL;DR: A hypothetical degradation pathway for the anaerobic oxidation of toLUene to benzoyl-CoA via an initial addition of fumarate to the methyl group of toluene and following beta-oxidation of the benzylsuccinate formed is suggested.
Abstract: Toluene is degraded anoxically to CO2 by the denitrifying bacterium Thauera aromatica. Toluene first becomes oxidized to benzoyl-CoA by O2-independent reactions. Benzoyl-CoA is then reduced to non-aromatic products by benzoyl-CoA reductase. We set out to study the reactions employed for the initial activation of toluene and its oxidation to the level of benzoate. Evidence is provided for a novel way of toluene degradation based on experiments with cell-free extracts and with whole toluene-grown cells: Cell-free extracts oxidized [14C]toluene to [14C]benzoyl-CoA via several radioactive intermediates. This reaction was strictly dependent on the presence of fumarate, coenzyme A and nitrate as electron acceptor; acetyl-CoA and ATP were not necessary for the reaction. The first product formed in vitro was benzylsuccinate; (2H8)toluene was converted to (2H7)benzylsuccinate. Formation of benzylsuccinate from toluene was independent of coenzyme A and nitrate, but it required the presence of fumarate. Other tricarboxylic acid cycle intermediates were converted to fumarate in cell extracts and therefore could partially substitute for fumarate. [14C]Benzylsuccinate was oxidized further to [14C]benzoyl-CoA and [14C]benzoate in cell extracts if coenzyme A and nitrate were present. No benzyl alcohol and benzaldehyde and no phenylpropionate could be detected as intermediates. In isotope trapping experiments with cell suspensions, two intermediates from [14C]toluene were detected, benzoate and benzylsuccinate. This corroborates the sequence of reactions deduced from in vitro experiments. A hypothetical degradation pathway for the anaerobic oxidation of toluene to benzoyl-CoA via an initial addition of fumarate to the methyl group of toluene and following beta-oxidation of the benzylsuccinate formed is suggested.

283 citations


Journal ArticleDOI
TL;DR: N-Hydroxyphthalimide (NHPI) combined with Co(acac)(n)() (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions.
Abstract: A novel class of catalysts for alkane oxidation with molecular oxygen was examined. N-Hydroxyphthalimide (NHPI) combined with Co(acac)n (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions. Cycloalkanes were successfully oxidized with molecular oxygen in the presence of a catalytic amount of NHPI and Co(acac)2 in acetic acid at 100 °C to give the corresponding cycloalkanones and dicarboxylic acids. Alkylbenzenes were also oxidized with dioxygen using this catalytic system. For example, toluene was converted into benzoic acid in excellent yield under these conditions. Ethyl- and butylbenzenes were selectively oxidized at their α-positions to form the corresponding ketones, acetophenone, and 1-phenyl-1-butanone, respectively, in good yields. A key intermediate in this oxidation is believed to be the phthalimide N-oxyl radical generated from NHPI and molecular oxygen using a Co(II) species. The isotope effect (kH/kD) in t...

259 citations


Journal ArticleDOI
TL;DR: The synthesis and characterization of the tapered building blocks 3,4,5-tris(1H, 1H,2H, 2H,3H, 3H,4H, 4H,5H, 5H,6H, 6H,7H,8H, 8H-perfluorodododecan-1-yloxy)benzoic acid and methacrylates are described.
Abstract: The synthesis and characterization of the tapered building blocks 3,4,5-tris(1H,1H,2H,2H,3H,3H,4H,4H,5H,5H,6H,6H,7H,7H,8H,8H-perfluorododecan-1-yloxy)benzoic acid (11-8/4), 3,4,5-tris(1H,1H,2H,2H,3H,3H,4H,4H,5H,5H,6H,6H-perfluorododecan-1-yloxy)benzoic acid (11-6/6), 3,4,5-tris(1H,1H,2H,2H,3H,3H,4H,4H-perfluorododecan-1-yloxy)benzoic acid (11-4/8), 2-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}ethyl 3,4,5-tris(1H,1H,2H,2H,3H,3H,4H,4H,5H,5H,6H,6H,7H,7H,8H,8H-perfluorododecan-1-yloxy)benzoate (19-8/4), 2-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}ethyl 3,4,5-tris(1H,1H,2H,2H,3H,3H,4H,4H,5H,5H,6H,6H-perfluorododecan-1-yloxy)benzoate (19-6/6), and 2-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}ethyl 3,4,5-tris(1H,1H,2H,2H,3H,3H,4H,4H-perfluorododecan-1-yloxy)benzoate (19-4/8) and of the methacrylates and polymethacrylates of 19-8/4, 19-6/6, and 19-4/8 (i.e, 20-8/4, 20-6/6, 20-4/8 and respectively 21-8/4, 21-6/6, and 21-4/8) are described. All tapered building blocks 11-m/n, 19-m/n, and the polymers 21-m/n (where m + n = 12 and m ...

171 citations


Journal ArticleDOI
TL;DR: The X-ray crystallographic structure of porcine kidney D-amino acid oxidase, which had been expressed in Escherichia coli transformed with a vector containing DAO cDNA, was determined by the isomorphous replacement method for the complex form with benzoate.
Abstract: The X-ray crystallographic structure of porcine kidney D-amino acid oxidase, which had been expressed in Escherichia coli transformed with a vector containing DAO cDNA, was determined by the isomorphous replacement method for the complex form with benzoate. The known amino acid sequence, FAD and benzoate were fitted to an electron density map of 3.0 A resolution with an R-factor of 21.0%. The overall dimeric structure exhibits an elongated ellipsoidal framework. The prosthetic group, FAD, was found to be in an extended conformation, the isoalloxazine ring being buried in the protein core. The ADP moiety of FAD was located in the typical beta alpha beta dinucleotide binding motif, with the alpha-helix dipole stabilizing the pyrophosphate negative charge. The substrate analog, benzoate, is located on the re-face of the isoalloxazine ring, while the si-face is blocked by hydrophobic residues. The carboxylate group of benzoate is ion-paired with the Arg283 side chain and is within interacting distance with the hydroxy moiety of Tyr228. The phenol ring of Tyr224 is located just above the benzene ring of benzoate, implying the importance of this residue for catalysis. There is no positive charge or alpha-helix dipole near N(1) of flavin. Hydrogen bonds were observed at C(2) = O, N(3)-H, C(4) = O, and N(5) of the flavin ring.

120 citations



Journal ArticleDOI
TL;DR: In this paper, the infrared spectra of benzoic and deuterobenzoic acids isolated in Ar matrices were measured using the matrix-to-sample (M / S ) ratios 750 and 250.

112 citations


Journal ArticleDOI
TL;DR: In this article, a novel molecular recognition process using aromatic and aliphatic amino acids was studied using non-covalent processes such as hydrogen bonding, π−π, and hydrophobic interactions.
Abstract: Molecular recognition, via non-covalent processes such as hydrogen bonding, π−π, and hydrophobic interactions, is an important biological phenomenon for guests, such as drugs, proteins, and other important biological molecules with, for example, host DNA/RNA. We have studied a novel molecular recognition process using guests that encompass aromatic and aliphatic amino acids [l-alanine, l-glutamine (l-Gln), l-histidine, l-isoleucine (l-Ile), l-leucine (l-Leu), l-phenylalanine (l-Phe), l−proline, l-tryptophan (l-Trp), l-valine (l-Val)], substituted aromatic carboxylic acids [o-, m-, p-aminobenzoic acids (G1-3), benzoic acid (G4), phenylacetic acid (G5), p-methoxyphenylacetic acid (G6), o-methyoxybenzoic acid (G9), o-nitrobenzoic acid (G10)], and aliphatic carboxylic acids [cyclohexylacetic acid (G7), 1-adamantanecarboxylic acid (G8)] with supramolecular, bioorganometallic hosts, (η5-pentamethylcyclopentadienyl)rhodium (Cp*Rh)−nucleobase, nucleoside, and nucleotide cyclic trimer complexes, [Cp*Rh(9-methylade...

100 citations


Journal ArticleDOI
TL;DR: Multiple regression equations were obtained which described the contribution of some physiochemical and other structural properties of the compounds to their biological activity and showed that in food with a high protein or lipid content antilisterial activity was much lower than predicted, making the models unacceptable in such circumstances.
Abstract: The inhibition of a cocktail of 18 strains of Listeria monocytogenes by 24 mono-, di- and tri-substituted benzoic and cinnamic acids and 16 benzaldehydes was evaluated using the concentration (C) required to give a 50% growth inhibition under anaerobic conditions at 35 degree C and pH 6.2 as a measure of biological activity (BAV). Using the method of least squares, multiple regression equations were obtained which described the contribution of some physiochemical and other structural properties of the compounds to their biological activity. The equation that best described the activity of benzoic and cinnamic acids was [formula: see text] where K is a lipophilicity parameter determined by RP-HPLC and the effect of ionization is represented by pKa. Benzaldehydes behaved differently, their activity being best described by the equation. [formula: see text] where the activity is controlled by a steric parameter, the van der Waals volume (Vw), and an electronic-steric parameter for ortho substituents. Absence of a lipophilicity parameter indicates that partitioning into the cell membrane might not be required for antimicrobial activity. The models were tested in several food systems which showed that in food with a high protein or lipid content antilisterial activity was much lower than predicted, making the models unacceptable in such circumstances.

93 citations


Journal ArticleDOI
TL;DR: In this paper, a single crystal pulsed neutron diffraction study of benzoic acid has been carried out at four temperatures, 20, 50, 100 and 175 K. This has allowed accurate site occupancies to be obtained for the hydrogen atom disorder in the hydrogen bonded carboxylic acid dimer motif.

78 citations


Journal ArticleDOI
TL;DR: In this paper, the chemisorption of benzoic acid and aniline on Si(100)-2 × 1 at room temperature has been studied with high resolution electron energy loss spectroscopy (HREELS) and low electron energy diffraction (LEED).


Journal Article
TL;DR: Depletion of CoA and inhibition of the pertinent enzymes seem responsible for impairment of glycine conjugation of benzoic acid by LA, which may also impair renal tubular cell function, compromising the tubular secretion of benzoylglycine and causing acute renal failure.
Abstract: Glycine conjugation of benzoic acid is catalyzed by the mitochondrial enzymes benzoyl-coenzyme A(CoA) synthetase and benzoyl-CoA: glycine N-acyltransferase and requires ATP, CoA, and glycine as cosubstrates. Lipoic acid (LA), an important endogenous and also therapeutic compound, depletes hepatic CoA; therefore, it may interfere with glycine conjugation. To test this hypothesis, LA (0.5-1.5 mmol/kg ip) was given to anesthetized, glycine-loaded rats 1 hr before administration of benzoic acid (1 mmol/kg iv). LA inhibited glycine conjugation of benzoic acid in a dose-dependent manner as indicated by: 1) reduced clearance of benzoic acid from blood; 2) delayed appearance of benzoylglycine in blood; and 3) decreased excretion of benzoylglycine in urine. LA also decreased urinary excretion of injected benzoylglycine, indicating that reduced excretion of this metabolite after benzoic acid injection is caused by diminished formation and impaired renal transport of benzoylglycine. Urine formation was decreased by LA in a dose-dependent fashion, and acute renal failure was evident in rats receiving the highest dose. LA depleted hepatic CoA, carnitine, and glutathione, but not ATP, whereas it increased the hepatic concentration of glycine. In isolated and solubilized rat liver mitochondria, LA inhibited both benzoyl-CoA synthetase (IC50 approximately 1.5 mM) and benzoyl-CoA:glycine N-acyltransferase (IC50 approximately 0.3 mM). Thus, depletion of CoA and inhibition of the pertinent enzymes seem responsible for impairment of glycine conjugation of benzoic acid by LA. LA may also impair renal tubular cell function, compromising the tubular secretion of benzoylglycine and causing acute renal failure.

Journal ArticleDOI
TL;DR: In this paper, an expeditious total synthesis of the physiologically active fungal metabolite 1 was described, which was achieved in two steps upon reaction of the hexopyranos-2-ulosyl bromide 15 with the glycosyl acceptor 13, followed by reduction of the resulting β-δ-glycos-2uloside 16.

Journal ArticleDOI
TL;DR: The mechanism of oxidation of benzaldehyde to benzoic acid catalyzed by horse liver alcohol dehydrogenase (HLADH) has been investigated using the HLADH structure at 2.1 A resolution with NAD+ and pentafluorobenzyl alcohol in the active site to suggest a stepwise reaction which occurs subsequent to hydride transfer.
Abstract: The mechanism of oxidation of benzaldehyde to benzoic acid catalyzed by horse liver alcohol dehydrogenase (HLADH) has been investigated using the HLADH structure at 2.1 A resolution with NAD+ and pentafluorobenzyl alcohol in the active site [Ramaswamy et al. (1994) Biochemistry 33, 5230−5237]. Constructs for molecular dynamics (MD) investigations with HLADH were obtained by a best-fit superimposition of benzaldehyde or its hydrate on the pentafluorobenzyl alcohol bound to the active site Zn(II) ion. Equilibrium bond lengths, angles, and dihedral parameters for Zn(II) bonding residues His67, Cys46, and Cys174 were obtained from small-molecule X-ray crystal structures and an ab initio-derived parameterization of zinc in HLADH [Ryde, U. (1995) Proteins: Struct., Funct., Genet. 21, 40−56]. Dynamic simulations in CHARMM were carried out on the following three constructs to 100 ps: (MD1) enzyme with NAD+, benzaldehyde, and zinc-ligated HO- in the active site; (MD2) enzyme with NAD+ and hydrated benzaldehyde m...

Journal ArticleDOI
TL;DR: In this article, an intramolecular reduction of B-(o-benzoyl benzoic acid with diisopinocampheylborane, readily prepared by the treatment of o-benzoic acids with B-chlorodiisop-in-ocamphelborane was shown to provide 3-phenylphthalide in ≥96% ee. Unfortunately, this procedure is not as efficient for the preparation of 3-arylphthalides.

Journal ArticleDOI
TL;DR: In this article, a high-pressure cell of 200-mL volume is described for easy and quick determination of partition coefficients in a system containing an aqueous and a supercritical phase, and an organic substance.
Abstract: A new apparatus is described for easy and quick determination of partition coefficients in a system containing an aqueous and a supercritical phase, and an organic substance. The partition coefficient in this case is defined as the ratio of molar fractions of a substance in two different phases in equilibrium. The apparatus consists of a high-pressure cell of 200-mL volume. Equilibrium is attained by recirculation of the fluid phases. Samples can be taken from either phase by using six-way sampling valves. Quantitative analysis is carried out either by UV-spectroscopy or by gas chromatography. In the measurements, carbon dioxide was used as the supercritical fluid in studies of partitioning behavior of the organic compounds, phenol, benzoic acid, benzyl alcohol, 2-hexanone, vanillin, and caffeine. The experiments were carried out at temperatures ranging from 313 to 333 K and pressure of 8 to 30 MPa. Partition coefficients between 0.2 and 1.5 were found for phenol which roughly match the data previously reported by other authors. Partition coefficients of benzyl alcohol and benzoic acid were found to be in a similar range, whereas those of 2-hexanone turned out to be between 10 and 140. The partition coefficients obtained ranged from 0.02 to 0.25 for caffeine and 0.2 to 3 for vanillin.

Journal ArticleDOI
TL;DR: In this article, a series of monomeric benzoic acid systems under liquefaction-relevant conditions was studied and it was shown that decarboxylation rates of these acids range from a few percent in 1 h at 400 °C for unactivated acids to >98% for species activated by OH in the ortho or para positions.
Abstract: Decarboxylation of a series of monomeric benzoic acid systems under liquefaction-relevant conditions was studied. The principal findings are the following: (1) decarboxylation rates of benzoic acids range from a few percent in 1 h at 400 °C for unactivated acids to >98% for species activated by OH in the ortho or para positions; (2) coupling of unactivatiated benzoic acids as a direct result of decarboxylation tends to be very minor (generally <10%); (3) decarboxylation of hydroxy-activated benzoic acids results in products that are susceptible to subsequent electrophilic coupling reactions; (4) under strongly oxidizing conditions, namely the absence of scavengers and the presence of one-electron oxidants, coupling of even unactivated acids can be as much as 50% of the decarboxylations; (5) amine bases tend to promote decarboxylation but either inhibit or do not affect coupling; (6) H-donors inhibit coupling but promote decarboxylation in the presence of the electron transfer agent Fe3O4; (7) small amount...

Journal ArticleDOI
TL;DR: In this article, a schematic mechanism for the palladium-catalysed reductive carbonylation of aromatic nitro compounds is proposed, based on the results of the results presented in this paper.
Abstract: The addition of carboxylic acids such as benzoic acid derivatives as cocatalyst has been found to enhance the catalytic activity and selectivity of a Pd(phen) 2 (OTf) 2 catalyst system in the reductive carbonylation of aromatic nitro compounds. A strong dependency of the catalytic performance on the amount of cocatalyst in the reaction mixture was found, yet no influence of the p K a -value of the particular cocatalyst could be discovered. Though the accelerating influence of the acidic cocatalyst is mainly caused by the protons of the cocatalyst since proton transfer plays a crucial role in the catalytic cycle, the positive effects could not be achieved by the use of other carboxylic acids or sulphonic acids as cocatalyst. Buffered systems showed that traces of weakly coordinating anions should be present in order to stabilise various catalytic intermediates, whereas higher concentrations of anions result in a decrease of catalyst activity. The formation of azoxybenzene was suppressed under the influence of the protons of the aromatic carboxylic acid, leading to an improvement of the catalyst selectivity. Based on the results a schematic mechanism for the palladium-catalysed reductive carbonylation of aromatic nitro compounds is proposed.

Journal ArticleDOI
TL;DR: Strain 6 most likely belongs to a new species closely related to Clostridium species, which is a gram- variable, flagellated rod with a doubling time of 10 to 11 h in the presence of phenol which has a cellular fatty acid composition like that of C. hastiforme.
Abstract: A consortium of spore-forming bacteria transforming phenol to benzoic acid under anaerobic conditions was treated with antibiotics to eliminate the four Clostridium strains which were shown to be unable to accomplish this reaction in pure culture and coculture. Clostridium ghonii was inhibited by chloramphenicol (10 micrograms/ml), whereas Clostridium hastiforme (strain 3) and Clostridium glycolicum were inhibited by clindamycin (20 micrograms/ml), without the transformation of phenol being affected. Electron microscopic observations of resulting liquid subcultures revealed the presence of two different bacilli: a dominant C hastiforme strain (strain 2) (width, 1 micron) and an unidentified strain 6 (width, 0.6 micron) which was not detected on solid medium. Bacitracin (0.5 U/ml) changed the ratio of the strains in favor of strain 6. C hastiforme 2 was eliminated from this culture by dilution. The isolated strain 6 transformed phenol to benzoic acid and 4-hydroxybenzoic acid to phenol and benzoic acid in the presence of proteose peptone. Both of these activities are inducible. This strain is a gram- variable, flagellated rod with a doubling time of 10 to 11 h in the presence of phenol. It has a cellular fatty acid composition like that of C. hastiforme. However, strain 6 does not hydrolyze gelatin or produce indole. The 16S rRNA sequence of strain 6 was found to be most similar to that of some Clostridium species, with homology ranging from 80 to 86%. Tbe evolutionary relationships of strain 6 to different groups of Clostridium and Clostridium-related species revealed that it does not emerge from any of these groups. Strain 6 most likely belongs to a new species closely related to Clostridium species.

Journal ArticleDOI
TL;DR: Butanol-soluble neutral and acidic thearubigins were prepared by a combination of solvent extraction, fractional precipitation, and Toyopearl column chromatography as mentioned in this paper.
Abstract: Butanol-soluble neutral and acidic thearubigins were prepared by a combination of solvent extraction, fractional precipitation, and Toyopearl column chromatography These pigments showed similar properties to those of Roberts’ thearubigins on the paper chromatogram, and a convex broad band with several peaks on reversed-phase HPLC The thearubigins were methylated, degallated, and chemically degraded with KMnO4 under alkaline conditions From the degradation products, methyl esters of 4-methoxy benzoic acid, 3,4-dimethoxy benzoic acid, 3,4,5-trimethoxy benzoic acid, 3,4-dimethoxy-1,2-benzenedicarboxylic acid, 3,4-dimethoxy-1,5-benzenedicarboxylic acid, 3,4-dimethoxy-1,6-benzenedicarboxylic acid, 3,4,5-trimethoxy-1,2-benzenedicarboxylie acid, 4,5,6-trimethoxy-1,2,3-benzenetricarboxylic acid, 4,5,4′,5′-tetramethoxy-2,2′-diphenic acid, and 3,4,5,3′,4′,5′-hexamethoxy-2,2′-diphenic acid were detected by using GC-MS and GC-SIM The butanol-soluble neutral thearubigins, which had been purified by Toyopearl colum

Journal ArticleDOI
TL;DR: The split/combine method was demonstrated to work well to form mixtures of compounds based on 3-amino-5-hydroxybenzoic acid as a core structure and the amino and hydroxy positions were variably substituted.
Abstract: A non-peptide library of 2001 compounds has been prepared utilizing solid-phase techniques. The split/combine method was demonstrated to work well to form mixtures of compounds based on 3-amino-5-hydroxybenzoic acid as a core structure. The benzoic acid of the core structure served as the attachment point for the resin and the amino and hydroxy positions were variably substituted.


Journal ArticleDOI
TL;DR: In this article, the electrochemical Fenton reqction (simultaneous reduction of dioxygen and ferric ions) permits a controlled production of OH' radicals, which are used for the stepwise hydroxylation of benzoic acid to mono and polyhydroxylated products.
Abstract: The electrochemical Fenton reqction (simultaneous reduction of dioxygen and ferric ions) permits a controlled production of OH' radicals. These are used for the stepwise hydroxylation of benzoic acid to monoand polyhydroxylated products. The quantitative distribution of all the hydroxylated products is achieved by use of HF'LC. The overall reaction scheme is established and the rate constants of the individual steps are measured.

Journal ArticleDOI
TL;DR: In this article, the wettability of hydrocarbon reservoirs depends on how and to what extent the organic compounds are adsorbed onto the surfaces of calcite, quartz and clay.

Journal ArticleDOI
TL;DR: In this article, a photochemical reaction of neat toluene and 4-picoline in liquid organic oxygenated dispersions containing pure or iron-doped titania photocatalysts has been studied.
Abstract: The heterogeneous photocatalytic oxidation of neat toluene and 4-picoline in liquid organic oxygenated dispersions containing pure or iron-doped titania photocatalysts has been studied in a photochemical reactor radiating predominantly at 365–366 nm. The investigation correlates experimental conditions such as structural aspects, surface properties, concentration and chemical nature of the photocatalysts, and illumination times, with chemical yields and selectivity of products. For toluene, the main photocatalytic products found were benzaldehyde, benzyl alcohol and benzoic acid. In particular, our results show that traces of water present in the reaction system play an important role in the distribution of products. Likewise, the important role of the adsorption effects in photocatalysis based on semiconductors is emphasized. Thus, differences in the affinity and mode of the adsorption of different molecules (i.e., toluene, picolines) should give rise to differences in the distribution of the reaction products.

Patent
30 Jan 1996
TL;DR: A preservative for compositions having an aqueous phase is defined in this paper as 5 to 60% by weight of an organic acid selected from the group consisting of benzoic acid, 4-hydroxybenzoic acids, salicylic acid and formic acid.
Abstract: A preservative, for compositions having an aqueous phase, comprising a) 5 to 60% by weight of an organic acid selected from the group consisting of benzoic acid, 4-hydroxybenzoic acid, salicylic acid, formic acid, acetic acid, propionic acid, sorbic acid, undecylenic acid and dehydracetic acid or their mixtures including their sodium, potassium, calcium, magnesium, ammonium and ethanolamine salts b) 10 to 95% by weight of alcohols of the general formulae I, II or III ##STR1## in which R 1 denotes hydrogen, an n-alkyl, iso-alkyl or alkoxy radical having 1 to 3 C atoms, and R 2 and R 3 denote hydrogen or a CH 3 -- or C 2 H 5 -- radical and n has the value of 3 or 4, and c) 0.1 to 20% by weight of one or more poly(hexa-methylenebiguanide) salts of the general formula ##STR2## in which Z represents hydrochloride, acetate, lactate, benzoate, propionate, 4-hydroxybenzoate, sorbate or salicylate; and n has the value of 4 to 6, in combination in a customary carrier or solvent.

Journal ArticleDOI
TL;DR: High performance liquid chromatography method utilizing the ion-pair reagent tetrabutylammonium hydroxide and salicylic acid as an aromatic probe for quantification of hydroxyl radical formation was set up, and preliminary results indicate that the faecal flora are able to produce reactive oxygen species in abundance.
Abstract: The hypoxanthine/xanthine oxidase enzyme system is known to produce the superoxide ion and hydrogen peroxide during the hydroxylation of hypoxanthine via xanthine to uric acid. When chelated iron is included in this system, superoxide reduces iron (III) to iron(II) and the iron(II)-chelate further reacts with hydrogen peroxide to form the highly reactive hydroxyl radical. Because of the limitations of colourimetric and spectrophotometric techniques by which, to date, the mechanisms of hydroxyl radical formation in the hypoxanthine/xanthine oxidase system have been monitored, a high performance liquid chromatography method utilizing the ion-pair reagent tetrabutylammonium hydroxide and salicylic acid as an aromatic probe for quantification of hydroxyl radical formation was set up. In the hypoxanthine/xanthine oxidase system the major products of hydroxyl radical attack on salicylic acid were 2,5-dihydroxy benzoic acid and 2,3-dihydroxy benzoic acid in the approximate ratio of 5:1. That the hydroxyl radical is involved in the hydroxylation of salicylic acid in this system was demonstrated by the potency especially of dimethyl sulphoxide, butanol and ethanol as scavengers. Phytic acid, which is considered to be an important protective dietary constituent against colorectal cancer, inhibited hydroxylation of salicylic acid at a concentration one order of magnitude lower than the classical scavengers, but was only effective in the absence of EDTA. The method has been applied to the study of free radical generation in faeces, and preliminary results indicate that the faecal flora are able to produce reactive oxygen species in abundance.

Journal ArticleDOI
TL;DR: Findings indicate that the purified medium chain acyl-CoA synthetase is a major enzyme for glycine conjugation of benzoic acids with electron-donating groups in bovine live mitochondria.

Patent
Gloria Anne Breault1
17 Jun 1996
TL;DR: In this article, the authors defined an optionally substituted ring system for compounds of formula (I) where the -CH(R?3)N(R2)B-R1? and -OD groups are positioned in a 1,2 relationship to one another on ring carbon atoms and the ring atom positioned ortho to the -OD linking group (and therefore in the 3position relative to the CHR3NR2- linking group) is not substituted.
Abstract: The invention relates to compounds of formula (I), wherein A is an optionally substituted, ring system provided that the -CH(R?3)N(R2)B-R1? and -OD groups are positioned in a 1,2 relationship to one another on ring carbon atoms and the ring atom positioned ortho to the -OD linking group (and therefore in the 3-position relative to the -CHR3NR2- linking group) is not substituted; B is an optionally substituted ring system; R1 is positioned on ring B in a 1,3 or 1,4 relationship with the -CH(R3)N(R2)- linking group and is as defined in the description; R2 is hydrogen, C?1-6?alkyl, optionally substituted by hydroxy, cyano or trifluoromethyl, C2-6alkenyl (provided the double bond is not in the 1-position), (C2-6alkynyl (provided the triple bond is not in the 1-position), phenylC1-3alkyl or pyridylC1-3alkyl; R?3? is hydrogen, methyl or ethyl; D is hydrogen, an optionally substituted 5-7 membered carbocyclic ring containing one double bond, C?1-3?alkyl substituted by an optionally substituted 5-7 membered carbocyclic ring containing one double bond or D is of the formula -(CH2)nCH(R?4)C(R5)=C(R6)R7? and N-oxides of -NR2 where chemically possible; and S-oxides of sulphur containing rings where chemically possible; and pharmaceutically acceptable salts and in vivo hydrolysable esters and amides thereof; excluding 4-[5-carboxy-2-hydroxybenzylamino]benzoic acid, 4-[2,5-dihydroxybenzylamino]benzoic acid, 5-[2-hydroxybenzylamino]-2-hydroxybenzoic acid, 3-[2,5-dihydroxybenzylamino]benzoic acid, 4-[2,5-dihydroxybenzylamino]benzenecarboxamide, 3-[2-hydroxybenzylamino]benzoic acid, 4-[2,5-dihydroxybenzylamino]-2-hydroxybenzoic acid, 4-[hydroxybenzylamino]-2-hydroxybenzoic acid and 4[2-hydroxybenzylamino]benzoic acid. Processes for their preparation, intermediates in their preparation, their use as therapeutic agents and pharmaceutical compositions containing them.