Showing papers on "Benzoic acid published in 1998"

Oxidative Cross-Coupling of N-(2‘-Phenylphenyl)benzene- sulfonamides or Benzoic and Naphthoic Acids with Alkenes Using a Palladium−Copper Catalyst System under Air

Abstract: N-(2‘-Phenylphenyl)benzenesulfonamides react with acrylate esters accompanied via cleavage of the C−H bond at their 2‘-position in the presence of a catalyst system of Pd(OAc)2 and Cu(OAc)2 and a base under air to produce 5,6-dihydro-5-(benzenesulfonyl)phenanthridine-6-acetate derivatives in high yields. The reactions of benzoic acid with butyl acrylate and styrene can also give 3-[(butoxycarbonyl)methyl]phthalide and 3-phenylisocoumarin, respectively.

Benzene and toluene gas-phase photocatalytic degradation over H2O and HCL pretreated TiO2: by-products and mechanisms

Abstract: Photocatalytic oxidations of toluene and benzene in air were carried out over water (TiO 2 /H 2 O) and HCl (TiO 2 /HCl) pretreated TiO 2 as this latter pretreatment enhances the toluene removal rate. The main purpose was to identify intermediate products. No gas-phase by-products were detected by direct GC/FID analysis under our conditions despite the high aromatic concentration (50 mg m −3 ) and the short contact time (ms); this result illustrates an attractive capability of this air purification method. Adsorbed intermediate products recovered by extraction from the used photocatalysts were the same over TiO 2 /H 2 O and TiO 2 /HCl; i.e. no chlorinated products were found in this latter case. Benzoic acid, benzaldehyde, and benzyl alcohol were three major toluene intermediate products identified; trace derivatives of these products and of toluene that were monohydroxylated on the ring were also detected in catalyst extract samples. The benzene major by-product was phenol which was accompanied by hydroquinone and 1,4-benzoquinone. Acetic and formic acids were also formed from both benzene and toluene. For both aromatics, a water extraction of the used photocatalysts permitted separation of a yellow viscous material that settled between water and TiO 2 after centrifugation. We have not identified the products contained in this material but believe them to be polymeric products which may be at the origin of the decreased photocatalytic activity of used TiO 2 with respect to fresh TiO 2 . Finally, we discuss the photocatalytic oxidation pathways.

Evidence that sorbic acid does not inhibit yeast as a classic ‘weak acid preservative’

Abstract: Weak-acid preservatives are widely used to maintain microbial stability in foods and beverages. Classical weak-acid theory proposes that undissociated acid molecules pass through the plasma membrane, dissociate in the neutral pH of the cytoplasm, release protons and inhibit growth through acidification of the cytoplasm. Inhibitory concentrations of sorbic acid are shown to liberate fewer protons than other weak-acid preservatives. Sorbic acid shows similar inhibition to other six-carbon acids, alcohols and aldehydes, the latter being unable to act as weak acids. A survey of 22 yeasts showed high correlation between sorbate resistance and ethanol tolerance. Inhibition by short-chain acids or alcohols showed strong correlation with lipophilicity. It is proposed that sorbic acid acts as a membrane-active substance rather than as a weak-acid preservative.

Acylsulfamoyl benzoic acid amides, plant protection agents containing said acylsulfamoyl benzoic acid amides, and method for producing the same

Abstract: The invention relates to acylsulfamoyl benzoic acid amides of general formula (I), wherein R?1, R2, R3, R4 and R5? represent various organic radicals and X represents CH or N, and to plant protection agents containing said acylsulfamoyl benzoic acid amides.

Effect of diet on the urinary excretion of hippuric acid and other dietary-derived aromatics in rat. A complex interaction between diet, gut microflora and substrate specificity

Abstract: 1. A combined in vivo and in vitro study has been devised to investigate an observation, obtained by 1H NMR of urine, that Alp:AprSD (Wistar derived) rats kept under standard husbandry conditions did not excrete urinary hippuric acid (HA). meta-(hydroxyphenyl)-propionic acid ?m-HPPA? was identified as the major aromatic component in urine samples lacking HA. 2. Examination of urine from Alp:APrSD and Zucker (obese negative) rats fed various diets showed that the lack of HA/presence of m-HPPA was due to diet and not to the strain of animal. This observation was reinforced by the demonstration that the administration of benzoic acid (BA) to rats not previously excreting urinary HA resulted in the return of this component to the urinary excretion profile. Thus rats receiving the standard diet were still capable of glycine conjugation. 3. Changing the diet of rats excreting m-HPPA led to the cessation of m-HPPA excretion and the return of HA urine excretion. Interestingly, switching back to the original diet did not cause the loss of HA and the re-emergence of m-HPPA. 4. In vitro studies on the two enzyme systems responsible for glycine conjugation (benzoyl CoA:synthetase and benzoyl CoA:glycine N-acyltransferase) in isolated liver mitochondria showed that m-HPPA did not inhibit either enzyme. However, m-HPPA was not found to be a substrate for the first reaction step explaining why it was found in the urine as the free acid and not as a glycine conjugate. 5. The absence and presence of m-HPPA and hippuric acid is suggested to be due to a combination of differences in dietary precursors of substrates for glycine conjugation and a dietary dependent redistribution of the intestinal microflora responsible for breakdown of plant phenolics and aromatic amino acids. Taken collectively this study emphasises how a simple diet change can cause a profound change in metabolism.

Antimicrobial activity of 4-hydroxybenzoic acid and trans 4-hydroxycinnamic acid isolated and identified from rice hull

Abstract: Two antimicrobial substances in rice hull were isolated and identified as 4-hydroxybenzoic acid and trans 4-hydroxycinnamic acid by LC-MS, and 1H- and 13C-NMR. An evaluation of 50% inhibition of growth (IC50) revealed that the two substances had different inhibition profiles against various microorganisms. Most of the gram-positive and some gram-negative bacteria were sensitive to trans 4-hydroxycinnamic acid and 4-hydroxybenzoic acid at IC50 concentrations of 100-170 and 160 micrograms/ml, respectively.

The Biosynthesis of Salicylic Acid in Potato Plants

Abstract: Spraying potato (Solanum tuberosum L.) leaves with arachidonic acid (AA) at 1500 μg mL−1 led to a rapid local synthesis of salicylic acid (SA) and accumulation of a SA conjugate, which was shown to be 2-O-β-glucopyranosylsalicylic acid. Radiolabeling studies with untreated leaves showed that SA was synthesized from phenylalanine and that both cinnamic and benzoic acid were intermediates in the biosynthesis pathway. Using radiolabeled phenylalanine as a precursor, the specific activity of SA was found to be lower when leaves were treated with AA than in control leaves. Similar results were obtained when leaves were fed with the labeled putative intermediates cinnamic acid and benzoic acid. Application of 2-aminoindan-2-phosphonic acid at 40 μm, an inhibitor of phenylalanine ammonia-lyase, prior to treatment with AA inhibited the local accumulation of SA. When the putative intermediates were applied to leaves in the presence of 2-aminoindan-2-phosphonic acid, about 40% of the expected accumulation of free SA was recovered, but the amount of the conjugate remained constant.

Molecular imprinting of azobenzene carboxylic acid on a TiO2 ultrathin film by the surface sol-gel process

Abstract: Ultrathin films of titanium oxide gel imprinted with 4-(4-propyloxyphenylazo)benzoic acid (C3AzoCO2H) were prepared by repeated immersion of a gold-coated quartz crystal microbalance (QCM) electrode or a quartz plate in solutions of C3AzoCO2H and titanium butoxide (Ti(O-nBu)4) in toluene/ethanol. Regular film growth was confirmed by frequency decrement in QCM measurements and by the appearance of the azobenzene absorption in UV−vis spectroscopy. The template molecule could be completely removed upon treatment with 1% aqueous ammonia. The resulting films showed saturation binding of the template molecule in acetonitrile in less than 1 min. Binding of the template molecule was greatest among aromatic carboxylic acids that are structurally related to the template. A related ester showed a significant reduction in the binding efficiency. The surface sol-gel process provides a powerful tool for molecular imprinting in ultrathin metal oxide films.

Repression of Phenol Catabolism by Organic Acids in Ralstonia eutropha

Abstract: During batch growth of Ralstonia eutropha (previously named Alcaligenes eutrophus) on phenol in the presence of acetate, acetate was found to be the preferred substrate; this organic acid was rapidly metabolized, and the specific rate of phenol consumption was considerably decreased, although phenol consumption was not abolished. This decrease corresponded to a drop in phenol hydroxylase and catechol-2,3-dioxygenase specific activities, and the synthesis of the latter was repressed at the transcriptional level. Studies with a mutant not able to consume acetate indicated that the organic acid itself triggers the repression. Other organic acids were also found to repress phenol degradation. One of these, benzoate, was found to completely block the catabolism of phenol (diauxic growth). A mutant unable to metabolize benzoate was also unable to develop on benzoate-phenol mixtures, indicating that the organic acid rather than a metabolite involved in benzoate degradation was responsible for the repression observed.

Calcium Complexes of Carboxylate-Containing Polyamide with Sterically Disposed NH···O Hydrogen Bond: Detection of the Polyamide in Calcium Carbonate by 13C Cross-Polarization/Magic Angle Spinning Spectra

Abstract: Carboxylate-containing polyamides were synthesized from 2,6-di(amino)benzoic acid and dimethylmalonyl dichloride, isophthaloyl dichloride, and fumaryl dichloride. These polymers, {NHC6H3(COO)NHCOC(...

Self-Assembly of Liquid-Crystalline Polyamide Complexes through the Formation of Double Hydrogen Bonds between a 2,6-Bis(amino)pyridine Moiety and Benzoic Acids

Abstract: Supramolecular liquid-crystalline polymeric complexes derived from polyamides containing 2,6-bis(amino)pyridyl units in their main chains and benzoic acid derivatives have been obtained by the formation of intermolecular double hydrogen bonds. The polymeric complexes behave as single liquid-crystalline polymers and exhibit stable and enantiotropic mesophases. The hydrogen-bonded mesogens laterally connected by flexible spacers form a polymeric structure that is not simply classified as a main-chain or a side-chain type.

Reduction of benzoic acid on CeO2 and, the effect of additives

Abstract: Catalytic behaviour of CeO2 in the reduction of benzoic acid has been studied in the temperature range 523–723 K. Two types of catalytic behaviour are observed in the whole temperature range. One type is observed from 523 up to 723 K. In this range, the selectivity to benzaldehyde can be higher than 95% and the reaction proceeds by the redox (Mars and van Krevelen) mechanism, with the oxygen vacancy as the active site. The activity is controlled by the steady-state concentration of oxygen vacancies under reaction conditions. The second type behaviour is observed above 648 K. Under these conditions the conversion of benzoic acid achieves nearly 100%, but the selectivity to benzaldehyde decreases, while that to toluene and benzene increases. In this range of temperatures, the reaction proceeds too far, due to a very high concentration of vacancies. Besides the redox mechanism decar☐ylation (hydrogenolysis) of the relative stable adsorbed benzoic acid takes place. The results observed with the reaction of adsorbed benzoic acid, under a flow of H2 reflects the two types of reaction. The potential promotion effects by Al, Cr, Mn, Fe, Ga, Zr, In and Pb oxides added to CeO2 were investigated. The catalytic behaviour of CeO2 changes by the addition of the metal oxides, positive effects are observed after adding Mn, Zr, In and Pb oxides.

A cyanide-free lytic reagent composition and method for hemoglobin and cell analysis

Abstract: A cyanide-free lytic reagent composition and method for measuring the total hemoglobin concentration in a blood sample, for counting the number of leukocytes and for differential counting of three leukocyte subpopulations including lymphocytes, monocytes, and granulocytes are described The cyanide-free lytic reagent composition comprises a hemolytic surfactant selected from the group consisting of quaternary ammonium salts, pyridinium salts, organic phosphate esters, and alkyl sulfonates to lyse erythrocytes and release hemoglobin, and an organic ligand selected from the group consisting of triazole and its derivatives, tetrazole and its derivatives, alkaline metal salts of oxonic acid, melamine, aniline-2-sulfonic acid, quinaldic acid, 2-amino-1,3,4-thiadiazole, triazine and its derivatives, urazole, DL-pipecolinic acid, isonicotinamide, anthranilonitrile, 6-aza-2-thiothymine, adenine, 3-(2-thienyl)acrylic acid, benzoic acid and alkali metal and ammonium salts of benzoic acid, and pyrazine and its derivatives to form a stable chromogen with hemoglobin Alternatively, the organic ligands can be added to a suitable blood diluent for hemoglobin and leukocyte analysis

Inhibition of listeria monocytogenes by cinnamic acid: possible interaction of the acid with cysteinyl residues

Abstract: The effects of cinnamic acid (C 6 H 5 CH=CHCOOH) on L. monocytogenes strain Scott A and listeriolysin O (LLO) activity were studied. In addition, a possible mode of action of the acid was investigated. L. monocytogenes was more susceptible to cinnamic acid than to benzoic acid, and lowering the broth pH increased the inhibition. LLO activity was inhibited in the presence of 0.1% cinnamic or benzoic acid, and western blot analysis showed reduced intensity of listeriolysin bands in the presence of 0.2% of the acids. Addition of cysteine (5 mM) to cinnamic acid in PBS, pH 7.0, caused gradual reduction in UV absorption of the acid during incubation for 12 h . Cinnamic acid (≥0.5%, pH 7.0) inhibited glucose uptake and A TP production in resting cells of L. monocytogenes. Results suggest a role of the cinnamate anion in the antilisterial and anti-LLO activity and potential applications in the food industry.

Spectroscopic Study of Luminescence and Energy Transfer of Binary and Ternary Complexes of Rare Earth with Aromatic Carboxylic Acids and 1,10-Phenanthroline

Abstract: A series of rare earth (Gd, Eu, Tb) complexes with different substituent group carboxylic acids (ortho-hydroxylbenzioc acid, ortho-aminobenzoic acid and ortho- methoxy benzoic acid) and 1,10-phenanthroline were synthesized. The spectroscopic studies of the photophysical properties such as luminescence properties, energy match and intramolecular energy transfer were carried out. The lowest triplet state energies of ligands and the intramolecular energy transfer efficiencies were determined with the measurement of low phosphorescence spectra and lifetimes of Gd complexes.

Purification, characterization and immobilization of an NADPH-dependent enzyme involved in the chiral specific reduction of the keto ester M, an intermediate in the synthesis of an anti-asthma drug, Montelukast, from Microbacterium campoquemadoensis (MB5614)

Abstract: (S)(E)-2-{3-[3-[2-(7-chloro-2-quinolinyl)ethenyl]-phenyl]-3-hydroxypropyl} benzoic acid methyl ester,␣a key intermediate in the synthesis of the anti-asthma drug, Montelukast, was prepared from the corresponding ketone (keto ester M) by microbial transformation. The biotransforming organism, Microbacterium campoquemadoensis (MB5614), was discovered as a result of an extensive screening program and was used for the isolation and purification of the responsible enzyme. The enzyme is a soluble cytoplasmic protein which was purified as a complex with a low-molecular-mass molecule that had a visible-light absorption maximum at 460 nm. The purified enzyme has an apparent molecular mass of 60 kDa, when denatured, and is isolated in the native state as an oligomer. The isolated enzyme requires NADPH for its activity and reduces the keto ester M to the desired (S)-hydroxy ester with an enantiomeric excess greater than 95% at the optimum temperature of 30 °C and pH 8. The enzyme was immobilized on oxirane-activated acrylamide beads with some loss of activity, but it was fully active in a two-phase (water/hexane 25:75) solvent system, both as a free solution and in an immobilized form.

Aminocyclopentitols from N-Alkylpyridinium Salts: A photochemical approach

Abstract: The photolysis of N-alkylpyridinium halides 9a–e in alkaline H2O gave 6-azabicyclo[3.1.0]hexenol derivatives 10a–e. N–Substituents bearing ether, acetal, and alcohol functions were found to do not adversely influence the photochemical reaction course. The free OH groups of the N–(3-hydroxypropyl) derivative 10d were protected by benzoylation. The ensuing dibenzoate 14 underwent stereocontrolled opening of the aziridine ring on reaction with MeSH/BF3 to give a thioether 15. With benzoic acid in CHCI3, 10d gave the 4-hydroxy-5-aminocyclopent-2-enyl benzoate 11. The meso-2-aminocyclopent-4-ene-1,3-diol 12 was obtained by hydrolysis of 11. On reaction with Boc2O and NaI, the aziridine ring of 14 was converted to a bicyclic compound 17. Hydrolysis of 17 provided the trans-1,3-diol 18, the epimer of 12. Face-selective dihydroxylation of Boc-protected 12 gave a meso-aminocyclopentanetetrol 23 which was characterized upon peracetylation. Dihydroxylation of 15 provided a racemic analogue of epi-mannostatin A (26).

Cellulose Derivatives Synthesized via Isocyanate and Activated Ester Pathways in Homogeneous Solutions of Lithium Chloride/N,N-Dimethylacetamide

Abstract: Cellulose carbamate and ester derivatives were synthesized in homogeneous solutions of lithium chloride (LiCl)/N,N-dimemyl-acetamide (DMAc) by the reaction of cellulose with ethyl 4-isocyanatobenzoate and the activated esters of N,N-dimethyl-aminobenzoic acids. Comparative reactions were performed with phenyl isocyanate and the activated ester of benzoic acid. All reactions were followed spectroscopically by FTIR, 1H NMR, and 13C NMR. Degrees of substitution were calculated utilizing UV spectroscopy. The isocyanate reactions are facile allowing controllable degrees of substitution and high yields. By contrast, the activated ester pathway inherently results in lower degrees of substitution and lower yields due in part to undesirable side reactions.

Carbohydrate−Carbohydrate Interactions in Water with Glycophanes as Model Systems

Abstract: The synthesis and conformational properties of glycophanes 2 and 3 (cyclodextrin−cyclophane hybrid receptors containing two maltose units linked by (4-hydroxymethyl) benzoic acid spacer) are descri...