Showing papers on "Benzoic acid published in 1992"
TL;DR: In this article, the authors carried out the condensation of benzaldehyde with activated methylenic groups with different pK values, in the presence of a MgAl hydrotalcite catalyst.
273 citations
TL;DR: In this article, the thermodynamic parameters of binding biotin and the dye 2-(4'-hydroxyphenylazo)benzoic acid (HABA) to streptavidin have been determined and compared, together with X-ray crystal structures of the protein-ligand complexes and apostreptavidIN.
Abstract: The thermodynamic parameters of binding biotin and the dye 2-(4'-hydroxyphenylazo)benzoic acid (HABA) to streptavidin have been determined and are compared, together with X-ray crystal structures of the protein-ligand complexes and apostreptavidin
233 citations
TL;DR: These studies demonstrate marked differences in the urinary metabolite profile by the two routes, and provide an improved basis for determining the extent and main route of absorption of cypermethrin under occupational exposure conditions.
Abstract: 1 The pyrethroid insecticide cypermethrin was administered orally to six male volunteers as a single dose of 33 mg (cis: trans 1 : 1) and dermally to six volunteers at a dose of 31 mg/800 cm2 (cis : trans 56 : 44) as a soya oil-based formulation Urine samples were collected for up to 5 days and analysed for the metabolites cis and trans 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCVA), 3-phenoxybenzoic acid (3PBA) and 3-(4′-hydroxyphenoxy) benzoic acid (4OH3PBA) following an acid hydrolysis procedure2 Following oral dosing approx equal amounts of (cis + trans DCVA) and (3PBA + 4OH3PBA) were excreted with peak excretion rates occurring between 8 and 24 h after dosing The ratio of trans:cis DCVA was on average 2:1 Based on DCVA measurements the amount of cypermethrin absorbed was estimated to be between 27% and 57% (mean 36%) of the administered dose3 Peak urinary excretion rates of metabolites occurred between 12 and 36h after dermal dosing The amount of metabolites derived
189 citations
TL;DR: In this article, the role of phenyl substituent groups in the formation of surface complexes at the surface of titanium dioxide semiconducting ceramic membranes is investigated with cylindrical internal reflection-Fourier transform infrared (CIR-FTIR) spectroscopy.
Abstract: The role of phenyl substituent groups in the formation of surface complexes at the surface of titanium dioxide semiconducting ceramic membranes is investigated with cylindrical internal reflection-Fourier transform infrared (CIR-FTIR) spectroscopy. The CIR-FTIR study presented in this article allows for direct comparison between adsorption mechanisms derived from vibrational spectra at the semiconductor-liquid interface and surface structures influencing aqueous heterogeneous photochemical reactions. Therefore, chemisorption mechanisms we derived for benzoic acid and its substituted compounds could be used for the prediction of their photodegradation behavior. This IR investigation confirms that no adsorption is detectable on the rutile phase of TiO2, thus excluding the role of 5-fold coordinated Ti cations in the adsorption mechanisms. We observed that, for anatase surface, isolated carboxyl groups do not generate a favorable adsorption equilibrium (e.g., benzoic acid). It is proposed that amino and hydroxyl groups substituted in ortho position to a carboxyl group (e.g., salicylic, 3-chlorosalicylic, and anthranilic acids) may lead to a mononuclear bidentate coordination complex with 4-fold coordinated surface titanium cations. The higher adsorption level observed for phthalic acid is interpreted as due to its possibility of adsorbing on a greater number of anatase surface sites, by forming two different surface complexes, involving one or both carboxyl groups. A relationship between change in vibrational spectra of the carboxyl group, for substituted benzoic derivatives, and acidic dissociation constants is presented.
127 citations
TL;DR: The optimization of reversed-phase high-performance liquid chromatographic separation by the simultaneous variation of pH and solvent strength (%B) was studied for acidic and basic samples and the combination of these two variables was expected to be more useful than either variable alone.
69 citations
TL;DR: Porous microparticulate zirconium oxide shows very different selectivities and pH dependencies for the separation of benzoic acid derivatives than do conventional bonded-phase anion-exchange supports.
Abstract: Porous microparticulate zirconium oxide shows very different selectivities and pH dependencies for the separation of benzoic acid derivatives than do conventional bonded-phase anion-exchange supports This results from a very significant ligand-exchange contribution to the retention of hard Lewis bases on the surface of transition-metal oxide supports We have found that the capacity factors of a wide variety of derivatives of benzoic acid are closely correlated with their Bronsted acidities The eluent pH is also a critical factor in determining the magnitude of the capacity factor, but it does not have much influence on chromatographic selectivity The differential selectivity of this phase in comparison to conventional polymeric and bonded-phase anion exchangers can be attributed to complexation and steric effects which profoundly alter the elution patterns of certain solutes
67 citations
TL;DR: In this article, the Keggin-type heteropolytungstic acids were used as electrophiles in Friedel-Crafts alkylation and acylation.
Abstract: Acidic salts of the Keggin-type heteropolytungstic acids prepared through partial neutralization with alkali metal carbonates or ammonium hydroxide had relatively large surface areas, and showed high catalytic efficiency as insoluble solid acid catalysts in Friedel-Crafts alkylation and acylation using benzyl chloride, benzoyl chloride, benzoic anhydride, benzoic acid, acetic anhydride, and acetic acid as electrophiles.
64 citations
TL;DR: Results suggest that these cyclohexadienecarboxylates, probably as their coenzyme A esters, are the initial reduction products formed during anaerobic benzoate metabolism by R. palustris.
Abstract: Alkali-treated extracts of Rhodopseudomonas palustris growing photosynthetically on benzoate were examined by gas chromatography/mass spectrometry for partially reduced benzoate derivatives. Two cyclic dienes, cyclohexa-2,5-diene-1-carboxylate and cyclohexa-1,4-diene-1-carboxylate, were detected. Either compound supported cell growth as effectively as benzoate. These results suggest that these cyclohexadienecarboxylates, probably as their coenzyme A esters, are the initial reduction products formed during anaerobic benzoate metabolism by R. palustris.
60 citations
TL;DR: A general scheme for obtaining a fluorescent donor/acceptor peptide substrate via solid-phase synthesis methodology is presented and substrates for renin and HIV proteinase are synthesized as examples.
Abstract: A general scheme for obtaining a fluorescent donor/acceptor peptide substrate via solid-phase synthesis methodology is presented. The key feature of this method is the design of a glutamic acid derivative that has been modified on the carboxyl side chain with a 5-[(2'-aminoethyl)-amino]naphthelenesulfonic acid (EDANS) to create a fluorescent donor moiety that can be incorporated near the C-terminus of the peptide substrate. The corresponding fluorescent acceptor group containing a 4-[[4-(dimethylamino)phenyl]azo]benzoic acid (DABCYL) can then be attached to the resin-bound peptide at the N-terminus while all side-chain groups are still fully protected. Substrates for renin and HIV proteinase are synthesized as examples.
57 citations
TL;DR: The in vitro: in vivo correlation supports the use of the flow-through diffusion cell system as a model for the prediction of percutaneous absorption in vivo in the rat and in humans.
TL;DR: A series of benzoic acid derivatives [2,4-di-NO 2, 3,4 -di- NO 2, p-NO 3, 3 4 -di NO 2 ], p-CF 3 and p-Cl, p-H and p6CH 3 were used in living cationic polymerization of isobutyl vinyl ether (IBVE) in toluene at 0°C as mentioned in this paper.
Abstract: A series of benzoic acid derivatives [2,4-di-NO 2 , 3,4-di-NO 2 , p-NO 2 , p-CF 3 , p-Cl, p-CH 3 , and p-H (unsubstituted)], in conjunction with zinc chloride (ZnCl 2 ), led to living cationic polymerization of isobutyl vinyl ether (IBVE) in toluene at 0°C. With p-CF 3 , p-Cl, p-H and p6CH 3 benzoic acids, though the M n values were larger than those calculated at the early stages of the polymerization,, they agreed with the calculated values at higher conversions. The molecular weight distributions of the polymers become broader as the acidity of the benzoic acids decreased
TL;DR: Micellar electrokinetic capillary chromatography (MECC) based on cetyltrimethylammonium bromide (CTAB) was developed for separation of individual cinnamic and benzoic acid derivatives.
TL;DR: Experiments with [(14)C]SA and [(14]C]benzoic acid have provided evidence that at pH 4 there is relatively more uptake of benzoic Acid than SA, thus leading to an increased flowering response.
Abstract: Lemna paucicostata LP6 does not normally flower when grown on basal Bonner-Devirian medium, but substantial flowering is obtained when 10 μm salicylic acid (SA) or benzoic acid is added to the medium. Benzoic acid is somewhat more effective than SA, and the threshold level of both SA and benzoic acid required for flower initiation is reduced as the pH of the medium is lowered to 4.0. SA- or benzoic acid-induced flowering is enhanced in the simultaneous presence of 6-benzylaminopurine (BAP), although BAP per se does not influence flowering in strain LP6. Continuous presence of SA or benzoic acid in the culture medium is essential to obtain maximal flowering. A short-term treatment of the plants (for first 24 h) with 10 μm SA or benzoic acid, followed by culture in the basal medium containing 1 μm BAP can, however, stimulate profuse flowering. Benzoic acid is more effective than SA, and the effect is more pronounced at pH 4 than at 5.5. Thus, under these conditions, flowering is of an inductive nature. Experiments with [14C]SA and [14C]benzoic acid have provided evidence that at pH 4 there is relatively more uptake of benzoic acid than SA, thus leading to an increased flowering response. The data obtained from the experiments designed to study the mobility of [14C]SA and [14C]-benzoic acid from mother to daughter fronds indicate that there is virtually no mobility of SA or benzoic acid between fronds.
TL;DR: It is suggested that one function of naturally occurring coniferyl and cinnamyl derivatives may be chemical defense in agricultural crops, as an inherent defense against pests and pathogens, may be possible.
Abstract: Phenylpropanoids, a class of common phenolic compounds in plants, may potentially be useful as pest repellents. We investigated the relationship between the chemical structure of coniferyl benzoate and its repellency to birds by comparing coniferyl benzoate to two analogous natural esters, corresponding alcohols, and benzoic acid. The absolute and relative feeding repellency of these compounds were assessed in choice (two-cup) and no-choice (one-cup) tests using European Starlings (Sturnus vulgaris). In addition, benzoin Siam (= gum benzoin Siam) was compared to coniferyl benzoate to ascertain if phenolics that naturally occur with coniferyl benzoate in benzoin Siam enhance its repellency. Two-cup tests suggested that coniferyl alcohol was the most repellent compound followed by 3,4-dimethoxycinnamyl alcohol, 3,4-dimethoxycinnamyl benzoate, cinnamyl alcohol, cinnamyl benzoate, coniferyl benzoate, and benzoic acid. The repellency of most alcohols relative to their corresponding ester reversed in the one-cup tests. One-cup tests suggested that 3,4-dimethoxycinnamyl benzoate was the most repellent substance followed by cinnamyl benzoate, benzoin Siam, 3,4-dimethoxycinnamylalcohol, cinnamyl alcohol, coniferyl alcohol, coniferyl benzoate, and benzoic acid. Three conclusions on structure-activity relationships were inferred from these data. First, benzoate esters are more repellent than their corresponding alcohols.Second, repellency is increased by electron-donating groups. Third, acidic functions decrease repellency. We suggest that one function of naturally occurring coniferyl and cinnamyl derivatives may be chemical defense. Genetically engineering agricultural crops to produce analogs of coniferyl alcohol, as an inherent defense against pests and pathogens, may be possible.
TL;DR: In this paper, three routes were explored for their potential to produce the aromatic aldehydes benzaldehyde, p -hydroxybenzaldehyde, and vanillin, which are important flavor components.
TL;DR: In this paper, a set of computed molecular properties, both steric and electronic, have been calculated using molecular orbital and empirical methods for benzoic acid and a congeneric series of substituted benzosic acids.
TL;DR: A series of new substrates for determining the catalytic activity of cysteine proteinases is described, using 5‐[(2‐aminoethyl)amino]naphtalene‐1‐sulfonic acid (EDANS) and 4‐(4‐dimethylaminophenylazo)benzoic acid (DABCYL)
TL;DR: The antioxidative properties of the derivatives of the benzoic acid have weaker inhibiting properties than is the case of the corresponding analogues of the cinnamic acid due to the more active participation of the inhibitor in the elementary reactions of propagation and initiation of the radical chain process as discussed by the authors.
Abstract: The antioxidative properies of p-hydroxy-benzole acid, vanillic acid, syringic acid, 3,4-dihydroxy-benzoic acid, p-coumaric acid, ferulic acid, sinaptic acid and caffeic acid in lard autoxidation at 100 o C are compared. It is proved that the derivatives of the benzoic acid have weaker inhibiting properties than is the case of the corresponding analogues of the cinnamic acid due to the more active participation of the inhibitor in the elementary reactions of propagation and initiation of the radical chain process
TL;DR: Evidence for a new reductive pathway of aromatic metabolism and for four enzymes catalyzing the initial steps is presented, which suggests a sequential induction of the enzymes.
Abstract: The enzymes catalyzing the initial reactions in the anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) were studied with a denitrifying Pseudomonas sp anaerobically grown with 2-aminobenzoate and nitrate as the sole carbon and energy sources Cells grown on 2-aminobenzoate are simultaneously adapted to growth with benzoate, whereas cells grown on benzoate degrade 2-aminobenzoate several times less efficiently than benzoate Evidence for a new reductive pathway of aromatic metabolism and for four enzymes catalyzing the initial steps is presented The organism contains 2-aminobenzoate-coenzyme A ligase (2-aminobenzoate-CoA ligase), which forms 2-aminobenzoyl-CoA 2-Aminobenzoyl-CoA is then reductively deaminated to benzoyl-CoA by an oxygen-sensitive enzyme, 2-aminobenzoyl-CoA reductase (deaminating), which requires a low potential reductant [Ti(III)] The specific activity is 15 nmol of 2-aminobenzoyl-CoA reduced min-1 mg-1 of protein at an optimal pH of 7 The two enzymes are induced by the substrate under anaerobic conditions only Benzoyl-CoA is further converted in vitro by reduction with Ti(III) to six products; the same products are formed when benzoyl-CoA or 2-aminobenzoyl-CoA is incubated under reducing conditions Two of them were identified preliminarily One product is cyclohex-1-enecarboxyl-CoA, the other is trans-2-hydroxycyclohexane-carboxyl-CoA The complex transformation of benzoyl-CoA is ascribed to at least two enzymes, benzoyl-CoA reductase (aromatic ring reducing) and cyclohex-1-enecarboxyl-CoA hydratase The reduction of benzoyl-CoA to alicyclic compounds is catalyzed by extracts from cells grown anaerobically on either 2-aminobenzoate or benzoate at almost the same rate (10 to 15 nmol min-1 mg-1 of protein) In contrast, extracts from cells grown anaerobically on acetate or grown aerobically on benzoate or 2-aminobenzoate are inactive This suggests a sequential induction of the enzymes
TL;DR: The two-phase reaction of benzoyl chloride (PhCOCl) and benzoate ion with pyridine 1-oxide (PNO) as the inverse phase transfer catalyst yields both the substitution product (benzoic anhydride) and the hydrolysis product (Benzoic acid).
Abstract: The two-phase reaction of benzoyl chloride (PhCOCl) and benzoate ion with pyridine 1-oxide (PNO) as the inverse phase transfer catalyst yields both the substitution product (benzoic anhydride) and the hydrolysis product (benzoic acid). A high yield (>95%) of benzoic anhydride can be obtained if a polar organic solvent like dichloromethane is used. Under appropriate conditions, this reaction follows the rate law-d[PhCOCl] org /dt =(k h +k c [PNO] iaq )[PhCOCl] org
TL;DR: The presence of 2,3-dihydroxy benzoic acid (DHBA) and 3,4-DHBA in the siderophore extract induced growth ofRhizobium in a medium containing EDTA and addition of lysine and alanine in the growth medium led to a fourfold increase in siderophile production.
Abstract: In an iron-depleted broth culture of cowpeaRhizobium (a peanut isolate), phenolate type of compounds were detected. Chemical characterization showed the presence of 2,3-dihydroxy benzoic acid (DHBA) and 3,4-DHBA in the siderophore extract. Lysine and alanine were identified as conjugated amino acids of the siderophore. Maximum concentration of the siderophore in the culture supernatant was found after 24 h of growth. The compounds in the extracted siderophore induced growth ofRhizobium in a medium containing EDTA. Addition of lysine and alanine in the growth medium (20 mM each) led to a fourfold increase in siderophore production.
TL;DR: Benzoate activation was inhibited by more than 6 mM ATP, presumably by pyrophosphate generation from ATP, and no homology of the N-terminal amino acid sequence with that of a 2-aminobenzoyl-CoA ligase of a denitrifying Pseudomonas sp.
Abstract: The benzoyl-CoA ligase from an anaerobic syntrophic culture was purified to homogeneity. It had a molecular mass of around 420 kDa and consisted of seven or eight subunits of 58 kDa. The temperature optimum was 37–40° C, the optimum pH around 8.0 and optimal activity required 50–100 mM TRIS-HCI buffer, pH 8.0 and 3–7 mM MgCl2; MgCl2 in excess of 10 mM was inhibitory. The activation energy for benzoate was 11.3 kcal/mol. Although growth occured only with benzoate as a carbon source, the benzoyl-coenzyme A (CoA) ligase formed benzoyl-CoA esters with benzoate, 2-, 3- and 4-fluorobenzoate, picolinate, nicotinate and isonicotinate. Acetate was activated to acetyl-CoA by an acetyl-CoA synthetase. The Km values for benzoate, 2-, 3- and 4-fluorobenzoate were 0.04, 0.28, 1.48 and 0.32 mM, the Vmax values 1.05, 1.0, 0.7 and 0.98 units (U)/mg, respectively. For reduced CoA (CoA-SH) a Km of 0.17 mM and a Vmax of 1.05 U/mg and for ATP a Km of 0.16 mM and a Vmax of 1.08 U/mg was determined. Benzoate activation was inhibited by more than 6 mM ATP, presumably by pyrophosphate generation from ATP. The inhibition constant (Ki) for pyrophosphate was 5.7 mM. No homology of the N-terminal amino acid sequence with that of a 2-aminobenzoyl-CoA ligase of a denitrifying Pseudomonas sp. was found.
TL;DR: The reaction products formed upon exposure of selected artists' colorants to gas-phase nitric acid have been identified using chemical ionization mass spectrometry in this paper, and the corresponding reaction mechanisms are outlined.
Abstract: The reaction products formed upon exposure of selected
artists' colorants to gas-phase nitric acid have been identified
using chemical ionization mass spectrometry. The
two organic colorants that were most nitric acid-fugitive
were triphenylmethane derivatives: the chloride cationic
dye basic fuchsin yielded the corresponding nitrate salt,
and the carbinol pararosaniline yielded the corresponding
organic nitrate ester. Both also yielded small amounts of
benzophenones. Other colorants studied yielded only small
amounts of oxidation (but not nitration) products, i.e.,
phenols and/or ring-opening products: benzoic acid and
hydroxyquinacridone from acridones, isatin and isatoic
anhydride from indigo, trihydroxyanthraquinone from
alizarin, and phthalic acid from Alizarin Crimson. The
corresponding reaction mechanisms are outlined. The
results are discussed in terms of possible damage to colorants
in museum collections resulting from exposure to
atmospheric nitric acid.
TL;DR: The metabolic pathway of phenylmalonic acid by Alcaligenesbronchisepticus KU1201, which catalyzes the asymmetric decarboxylation of α- Daryl-α-methylmalonic acids to α-arylpropionic acids, is demonstrated and enzymatic oxidation is applicable to various substituted mandelic acids.
Abstract: The metabolic pathway of phenylmalonic acid byAlcaligenes
bronchisepticus KU1201, which catalyzes the asymmetric decarboxylation of α-aryl-α-methylmalonic acids to α-arylpropionic acids, is demonstrated. Enantioselective oxidation of mandelic acid was investigated using the metabolizing pathway in this strain. Incubation of (±)-mandelic acid withA.
bronchisepticus afforded optically pure (R)-one accompanied by benzoylformic acid and benzoic acid. This enzymatic oxidation is also applicable to various substituted mandelic acids.
TL;DR: In this article, various phenols with an acyl group conjugated to the aromatic system were converted via trifluoromethanesulfonates into benzoic acid esters by a palladium catalyzed alkoxy/aryloxy carbonylation.
TL;DR: In this article, the reaction of Mn(O2CPh)2·.4H2O with KMnO4 in warm ethanol in the presence of benzoic acid has been found to give, in addition to the previously reported “manganic benzoate”, the new hexanuclear mixed-valence manganese cluster [Mn6O2 (O 2CPh10(EtOH)4(H 2O)]·.
TL;DR: In this paper, the reaction of benzoic acid with bromobutane was carried out in toluene or acetonitrile in the presence of polymer-supported 1,5,7-triazabicyclo[4.4.0]deca-5-ene (TBD).
Abstract: Polymer-supported 1,5,7-triazabicyclo[4.4.0]deca-5-ene (TBD) was prepared by the reaction of chloromethylated polystyrene resins, cross-linked with 2 mol% of divinylbenzene, with TBD. The reaction of benzoic acid with bromobutane was carried out in toluene or acetonitrile in the presence of polymer-supported TBD or polymer-supported 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The rate of esterification was dependent on the ring substitution of the supported bases and the solvent. The reduced ring substitution resulted in the increased swellability of the polymeric beads containing benzoate or bromide ions for toluene and thereby in the increased reaction rate. The rate with the high ring-substituted bases increased in acetonitrile, because of the high swellability of the immobilized salts and the high nucleophilicity of benzoate anion in the solvent. The supported bases were also effective for alkylation of an active methylene compound with bromoalkane.
TL;DR: In this paper, the Mitsunobu reaction with benzoic acid gave a low yield of a 1:1 mixture of the benzoate derivatives (6b and 5b) resulting from inversion and retention of configuration, respectively, at C-1.
Abstract: Reaction of (1S,7aS)-1-hydroxy-7a-methyl-7,7a-dihydro-5(6H)-indanone (5a) with benzoic acid under the unsual conditions of the Mitsunobu reaction gave a low yield of a 1:1 mixture of the benzoate derivatives (6b and 5b) resulting from inversion and retention of configuration, respectively, at C-1. Under conditions in which the benzoic acid concentration was kept low, only the inversion product 6b was obtained but the extent of conversion of the alcohol to the ester was low. The substitution of p-nitrobenzoic and for benzoic led to a significant improvement in the yield of the inversion product 6c