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Showing papers on "Benzoic acid published in 2005"


Journal ArticleDOI
TL;DR: Examination of the oxidizing capacity of a range of Fe0 particles reveals a capacity in all cases to induce oxidative transformation of benzoic acid, but the high surface areas that can be achieved with nanosized particles renders such particles particularly effective oxidants.
Abstract: Addition of nanoparticulate zero-valent iron (nZVI) to oxygen-containing water results in oxidation of organic compounds. To assess the potential application of nZVI for oxidative transformation of organic contaminants, the conversion of benzoic acid (BA) to p-hydroxybenzoic acid (p-HBA) was used as a probe reaction. When nZVI was added to BA-containing water, an initial pulse of p-HBA was detected during the first 30 min, followed by the slow generation of additional p-HBA over periods of at least 24 h. The yield of p-HBA increased with increasing BA concentration, presumably due to the increasing 'ability of BA to compete with alternate oxidant sinks, such as ferrous iron. At pH 3, maximum yields of p-HBA during the initial phase of the reaction of up to 25% were observed. The initial rate of nZVI-mediated oxidation of BA exhibited a marked reduction at pH values above 3. Despite the decrease in oxidant production rate, p-HBA was observed during the initial reaction phase at pH values up to 8. Competition experiments with probe compounds expected to exhibit different affinities for the nZVI surface (phenol, aniline, o-hydroxybenzoic acid, and synthetic humic acids) indicated relative rates of reaction that were similar to those observed in competition experiments in which hydroxyl radicals were generated in solution. Examination of the oxidizing capacity of a range of Fe0 particles reveals a capacity in all cases to induce oxidative transformation of benzoic acid, but the high surface areas that can be achieved with nanosized particles renders such particles particularly effective oxidants.

418 citations



Journal ArticleDOI
TL;DR: The developed method was applied to the determination of 67 foodstuffs, comprising soft drinks, jams, sauces, canned fruits/vegetables, dried vegetables/fruits and others, and found the range of preservatives found were from not detected to not detected.

236 citations


Journal ArticleDOI
TL;DR: Application of the resolved bis-3,4-diazaphosholanes to Rh-catalyzed enantioselective hydroformylation of styrene, allyl cyanide, and vinyl acetate under mild pressures and temperatures reveals high activities and selectivities for all three substrates.
Abstract: Azines made by the reaction of hydrazine with ortho-formylbenzoic acid react with 1,2-diphosphinobenzene and either succinyl chloride or phthaloyl chloride in ca. 30% yield to give rac-bis-3,4-diazaphospholanes bearing benzoic acid groups in the 2 and 5 positions. Condensation of the benzoic acid functionalities with enantiomerically pure amines affords diastereomeric benzoamides which can be separated by flash chromatography. Application of the resolved bis-3,4-diazaphosholanes to Rh-catalyzed enantioselective hydroformylation of styrene, allyl cyanide, and vinyl acetate under mild pressures (20−500 psig of CO/H2) and temperatures (40−120 °C) reveals high activities and selectivities for all three substrates. At 60 °C and 500 psig syn gas, the best ligand provides outstanding regio- and enantioselectivities (styrene, 89% ee, b:l = 30:1; allyl cyanide, 87% ee, b:l = 4.8:1; vinyl acetate, 95% ee, b:l = 40:1) while achieving turnover frequencies of ca. 3000 h-1.

169 citations


Journal Article
TL;DR: Both molecular modelling and FTIR have been used to study carboxyl group among acetic acid, potassium and sodium acetate, glycine, sodium salicylate, salicylic acid and cellulose acetate.
Abstract: Both molecular modelling and FTIR have been used to study carboxyl group among acetic acid, potassium and sodium acetate, glycine, sodium salicylate, salicylic acid and cellulose acetate Molecular modelling was used to study formic acid carhoxylic acids R-COOH, monovalent alkali carboxylate CH 3 COO-M, alanine, benzoic acid as well as naphthalene Each structure was optimized using VWN/DZVP then vibrational spectra were further calculated at the same level of theory The comparison between both calculated and experimental spectra showed good agreement with each other Except for formic acid and free carboxyl, the characteristic band is shifted towards lower frequency

151 citations


Journal ArticleDOI
TL;DR: The occurrence of the hydrogenolysis of the C-O bond of benzyl alcohol and formation of toluene indicates that Pd was present in a reduced state (Pd0) even in the presence of oxygen, in agreement with the dehydrogenation mechanism of alcohol oxidation.
Abstract: The palladium-catalyzed liquid-phase reaction of benzyl alcohol to benzaldehyde was investigated in the presence and absence of oxygen by attenuated total reflection infrared (ATR−IR) spectroscopy. The 5 wt % Pd/Al2O3 catalyst was fixed in a flow-through ATR−IR cell serving as a continuous-flow reactor. The reaction conditions (cyclohexane solvent, 323 K, 1 bar) were set in the range commonly applied in the heterogeneous catalytic aerobic oxidation of alcohols. The in situ ATR−IR study of the solid−liquid interface revealed a complex reaction network, including dehydrogenation of benzyl alcohol to benzaldehyde, decarbonylation of benzaldehyde, oxidation of hydrogen and CO on Pd, and formation of benzoic acid catalyzed by both Pd and Al2O3. Continuous formation of CO and its oxidative removal by air resulted in significant steady-state CO coverage of Pd during oxidation of benzyl alcohol. Unexpectedly, benzoic acid formed already in the early stage of the reaction and adsorbed strongly (irreversibly) on th...

151 citations


Journal ArticleDOI
TL;DR: In this article, a simple and convenient procedure for reductive amination of aldehydes and ketones using sodium borohydride activated by boric acid, p-toluenesulfonic acid monohydrate or benzoic acid as reducing agent under solvent-free conditions is described.

145 citations


Journal ArticleDOI
TL;DR: In this paper, Schiff bases have been synthesized: (1) 4-(2-chlorobenzylidene)amino benzoic acid JP1, (2) 4 (furan-2-ylmethylene) amino benzylide) acid JP2, (3) 4-[(3-phenylallylidene), amino]benzoic acids JP3, (4) 4(2-hydroxy-3-methoxybenzylidenes)amide JP4, (5) 4-hyd
Abstract: The following Schiff bases have been synthesized: (1) 4-(2-chlorobenzylidene)amino benzoic acid JP1, (2) 4 (furan-2-ylmethylene)amino benzoic acid JP2, (3) 4-[(3-phenylallylidene)amino]benzoic acid JP3, (4) 4 (2-hydroxybenzylidene)amino benzoic acid JP4, (5) 4 (4-hydroxy-3-methoxybenzylidene)amino benzoic acid JP5 and (6) 4 (3-nitrobenzylidene)amino benzoic acid JP6. They were screened as potential antibacterial agents against a number of medically important bacterial strains. The antibacterial activity was studied against A. faecalis ATCC 8750, E. aerogenes ATCC 13048, E. coli ATCC 25922, K. pneumoniae NCIM 2719 S. aureus ATCC 25923, P. vulgaris NCIM 8313, P. aeruginosa ATCC 27853 and S. typhimurium ATCC 23564. The antibacterial activity was evaluated using the Agar Ditch method. The solvents used were 1,4-dioxane and dimethyl sulfoxide. Different effects of the compounds were found in the bacterial strains in vestigated and the solvents used, suggesting, once again, that the antibacterial activity is dependent on the molecular structure of the compound, the solvent used and the bacterial strain under consideration. In the present work, 1,4-dioxane proved to be a good solvent in inhibiting the above stated bacterial strains.

141 citations


Journal ArticleDOI
TL;DR: It is proposed that styrene epoxide, benzoic acid, and benzeneacetic acid are produced via two possible oxametallacycle intermediates, which has implications for understanding the activity of nanoscale Au catalysts.
Abstract: For the first time, we demonstrate olefin epoxidation promoted by an extended Au surface. The oxidation of styrene to styrene epoxide, benzoic acid, and benzeneacetic acid is promoted on Au(111) covered with 0.2 ML of oxygen atoms. The estimated selectivity for styrene epoxide formation is approximately 53%. Total combustion to CO2 accounts for approximately 20% of the styrene reaction. We propose that styrene epoxide, benzoic acid, and benzeneacetic acid are produced via two possible oxametallacycle intermediates. Our work demonstrates that extended Au is an effective material for olefin oxidation, which has implications for understanding the activity of nanoscale Au catalysts.

128 citations


Journal ArticleDOI
TL;DR: Polyphenol oxidase of nettle was extracted and purified through (NH4)2SO4 precipitation, dialysis, and CM-Sephadex ion-exchange chromatography and was used for its characterization and found to be one of the most suitable substrates.
Abstract: Polyphenol oxidase (PPO) of nettle (Urtica dioica L.) was extracted and purified through (NH4)2SO4 precipitation, dialysis, and CM-Sephadex ion-exchange chromatography and was used for its characterization. The PPO showed activity to catechol, 4-methylcatechol, L-3,4-dihydroxyphenylalanine (L-DOPA), L-tyrosine, p-cresol, pyrogallol, catechin and trans-cinnamic acid. For each of these eight substrates, optimum conditions such as pH and temperature were determined and L-tyrosine was found to be one of the most suitable substrates. Optimum pH and temperature were found at pH 4.5 and 30 degrees C respectively and Km and Vmax values were 7.90 x 10(-4) M, and 11290 EU/mL for with L-tyrosine as substrate. The inhibitory effect of several inhibitors, L-cysteine chloride, sodium azide, sodium cyanide, benzoic acid, salicylic acid, L-ascorbic acid, glutathione, thiourea, sodium diethyl dithiocarbamate, beta-mercaptoethanol and sodium metabisulfite were tested. The most effective was found to be sodium diethyl dithiocarbamate which acted as a competitive inhibitor with a Ki value of 1.79 x 10(-9)M. In addition one isoenzyme of PPO was detected by native polacrylamide slab gel electrophoresis.

127 citations


Journal ArticleDOI
TL;DR: A convergent, enantioselective synthesis of (-)-tetracycline from benzoic acid is described, indistinguishable from an authentic sample.
Abstract: We describe a convergent, enantioselective synthesis of (−)-tetracycline (1) from benzoic acid (17 steps, 1.1% yield). Benzoic acid was transformed into the AB precursor 2 in 10 steps (11% yield), as previously described, and the latter compound was activated toward Diels−Alder cycloaddition by the introduction of an α-phenylthio group (two steps, 66% yield). Heating of the resulting α-(phenylthio)enone (3) with the triethylsilyloxybenzocyclobutene derivative 4 at 85 °C gave the endo-Diels Alder adduct 5 in 64% yield. Deprotection and oxidation of the latter intermediate gave the 2-(phenylthio)-1,3-diketone 7, which was oxidized with m-chloroperoxybenzoic acid in the presence of trifluoroacetic acid. The sulfoxide intermediate(s) formed eliminated upon warming to 35 °C to give the anyhydrotetracycline derivative 8. Intermediate 8 underwent spontaneous autoxidation at 23 °C to form the hydroperoxide keto-9 stereoselectively. Without isolation, hydrogenolysis of 9 in the presence of palladium black gave (−)...

Journal ArticleDOI
Qing-Xi Chen1, Kang-Kang Song1, Ling Qiu1, Xiaodan Liu1, Huang Huang1, Hua-Yun Guo1 
TL;DR: In this article, the inhibitory kinetics of the diphenolase of mushroom tyrosinase by seven p-alkoxybenzoic acids has been studied, and the results show that these derivatives of benzoic acid behave as reversible inhibitors.

Journal ArticleDOI
TL;DR: In this paper, the authors conducted liquid phase oxidation of toluene with molecular oxygen over heterogeneous catalysts of copper-based binary metal oxides and found that iron-copper bi-nary oxide (Fe/Cu ¼ 0.3 atomic ratio) was the best catalyst.
Abstract: We conducted the liquid phase oxidation of toluene with molecular oxygen over heterogeneous catalysts of copper-based binary metal oxides. Among the copper-based binary metaloxides, iron-copper bi- nary oxide (Fe/Cu ¼ 0.3 atomic ratio) was found to be the best catalyst. In the presence of pyridine, overox- idation of benzaldehyde to benzoic acid was partially prevented. As a result, highly selective formation of benzaldehyde (86% selectivity) was observed after 2 h of reaction (7% conversion of toluene) at 463 K and 1.0 MPa of oxygen atmosphere in the presence of pyridine. These catalytic performances were similar or better than those in the gas phase oxidation of tol- uene at reaction temperatures higher than 473 K and under 0.5 - 2.5 MPa. It was suggested from competi- tive adsorption measurements that pyridine could re- duce the adsorption of benzaldehyde. At a long reac- tion time of 4 h, the conversion increased to 25% and benzoic acid became the predominant reaction prod- uct (72% selectivity) in the absence of pyridine. The yield of benzoic acid was higher than that in the Snia-Viscosa process, which requires corrosive halo- gen ions and acidic solvents in the homogeneous reac- tion media. The catalyst was easily recycled by simple filtration and reusable after washing and drying.

Journal ArticleDOI
TL;DR: In this study, a two-phase swirl-flow monolithic-type reactor is used to study the kinetics of photocatalytic degradation of benzoic acid in immobilized systems.

Journal ArticleDOI
TL;DR: In this paper, the results indicate that quinones derived from dihydroxybenzoic acids participate in Michael addition reactions with acetylacetone and via various mechanisms convert to the corresponding benzofurans.

Journal ArticleDOI
TL;DR: The effect of temperature on the efficiency of degradation of the aromatic compounds benzoic acid, 2,3,5-trichlorobenzoic acids, phthalic acid and methylphthalate was examined in this paper.

Journal ArticleDOI
TL;DR: The new neutral catalytic protocol with the optimal TiO(acac)2 tolerates many stereo/electronic structural variations in both ( di)acid and (di)alcohol components with high chemoselectivity.
Abstract: A diverse array of oxometallic species were examined as catalysts for a test direct condensation of benzoic acid and 2-phenylethanol in 1:1 stoichiometry. Besides group IVB MOCl2−xH2O and TiOX2−xH2O, group VB VOCl2−xTHF and group IVB TiO(acac)2 were found to be the most efficient and water-tolerant catalysts for the test reaction. The new neutral catalytic protocol with the optimal TiO(acac)2 tolerates many stereo/electronic structural variations in both (di)acid (1°−3° alkyl and aryl) and (di)alcohol (1°, 2° alkyl, and aryl) components with high chemoselectivity.

Journal ArticleDOI
TL;DR: Six derivatives of the general formula 2- or 4-trifluoromethylquinolin-4-ylamino) benzoic acid N'-(nitrooxyacetyl or propionyl) hydrazide were synthesized and tested for their in vivo anti-inflammatory, analgesic, and ulcerogenic properties, as well as their in vitro nitric oxide release ability.

Journal ArticleDOI
TL;DR: Comparison between the two groups revealed that benzoate derivatives are much stronger hydrogen peroxide quenchers in relation with their cinnamate analogues, and this finding was discussed on a basis of structure-activity relationships and comparative assessment of other antioxidant characteristics.

Journal ArticleDOI
TL;DR: The acute immobilization toxicity of benzoic acids substituted with hydroxyl and/or methoxyl groups on the aromatic ring was determined for the freshwater crustacean Daphnia magna under neutralized condition and the toxicity variations appeared to be correlated with the logarithms of n-octanol/water partition coefficients (logPow).

Journal ArticleDOI
TL;DR: The iron-assisted hydroxylation of benzoic acid to salicylic acid by 1/H2O2 has been achieved in good yield under mild conditions and the product is a novel mononuclear iron(III) complex with a chelating salicylate.

Journal ArticleDOI
TL;DR: In this article, two modified organobentonites were synthesized using hexadecyltrimethyle ammonium bromide (HDTMAB) and octadecyl-trimethyltyl ammonium (ODTMA) to remove benzoic acid and hydroquinone from water.

Journal ArticleDOI
TL;DR: Direct dynamics calculations based on instanton techniques are reported of tunneling splittings due to double proton transfer in formic and benzoic acid dimers, finding that the splitting is considerably larger in the benzosic than in the formic aciddimer.
Abstract: Direct dynamics calculations based on instanton techniques are reported of tunneling splittings due to double proton transfer in formic and benzoic acid dimers. The results are used to assign the observed splittings to levels for which the authors of the high-resolution spectra could not provide a definitive assignment. In both cases the splitting is shown to be due mainly to the zero-point level rather than to the vibrationally or electronically excited level whose spectrum was investigated. This leads to zero-point splittings of 375MHz for (DCOOH)2 and 1107MHz for the benzoic acid dimer. Thus, contrary to earlier calculations, it is found that the splitting is considerably larger in the benzoic than in the formic acid dimer. The calculations are extended to solid benzoic acid where the asymmetry of the proton-transfer potential induced by the crystal can be overcome by suitable doping. This has allowed direct measurement of the interactions responsible for double proton transfer, which were found to be ...

Journal ArticleDOI
TL;DR: The aqueous Kolbe−Schmitt synthesis using resorcinol to yield 2,4-dihydroxy benzoic acid was performed in a microreactor rig as mentioned in this paper.

Journal ArticleDOI
Bing Yan1, Bing Zhou1
TL;DR: In this article, a series of luminescent dysprosium complexes with different aromatic carboxylic acids have been synthesized and characterized, and the photophysical properties of these complexes have been studied with all kinds of molecular spectroscopy.
Abstract: A series of luminescent dysprosium complexes with different aromatic carboxylic acids have been synthesized and characterized. The photophysical properties of these complexes have been studied with all kinds of molecular spectroscopy such as infrared spectra, ultraviolet spectra, phosphorescence spectra and fluorescence spectra. Especially the energy match and intramolecular energy transfer process between the triplet state energies of aromatic carboxylic acids and the resonant emissive energy level of Dy3+ was discussed in detail for the first time. Which indicates that the heterocyclic aromatic carboxylic acids (pyridine-carboxylic acids) are more suitable for the luminescence of Dy3+ than benzoic acid derivatives.

Journal ArticleDOI
TL;DR: An aqueous palladium catalyst that is stabilized by a water-soluble biquinoline-based ligand was employed for the aerobic oxidation of secondary and primary alcohols as discussed by the authors.
Abstract: An aqueous palladium catalyst that is stabilized by a water-soluble biquinoline-based ligand was employed for the aerobic oxidation of secondary and primary alcohols. Secondary alcohols afforded the corresponding ketones in high yield with selectivities greater than 90%. Aliphatic primary alcohols were fully oxidized to carboxylic acid products under the same reaction conditions, with various amounts of ester byproduct. Benzyl alcohol can be converted to a mixture of benzaldehyde and benzoic acid, where the relative amounts are dependent on the reaction conditions, while substituted benzylic alcohols gave primarily benzaldehyde derivatives. In contrast to related systems, the catalyst used in this study is tolerant of additional coordinating groups on the benzyl alcohol substrate. In all examples of alcohol oxidation, water is used as the only reaction solvent and air is used as the oxidant, thus these conversions could serve as environmentally benign “green” alternatives to traditional oxidation methods.

Journal ArticleDOI
TL;DR: The adsorption rate and the extent were found to be the highest at pH 3.7 and decreased at higher or lower pH values and the types of interactions governing in the Adsorption processes are discussed considering the surface charge and the dissociation of benzoic acid at different pH values.

Journal ArticleDOI
TL;DR: Enhancing atom economy of the metal-catalyzed asymmetric allylic alkylation shifts from the usual nucleophilic displacement of a leaving group to an addition of a pronucleophile to a double bond with excellent regioselectivity and enantiomeric excess under optimized conditions.
Abstract: Enhancing atom economy of the metal-catalyzed asymmetric allylic alkylation (AAA) shifts from the usual nucleophilic displacement of a leaving group to an addition of a pronucleophile to a double bond. Using 1-alkoxyallenes as proelectrophiles, the palladium-catalyzed AAA proceeds with 1,3-dicarbonyl compounds as pronucleophiles with excellent regioselectivity and enantiomeric excess under optimized conditions. The pH of the medium proved crucial for reactivity/ selectivity. By using the more acidic Meldrum's acids, the reactions required a co-catalytic amount of Bronsted acid. such as trifluoroacetic acid. Single regioisomeric products of 82-99% ee were obtained. On the other hand, the less acidic 1,3-diketones failed to react under such conditions. The fact that a less acidic acid like benzoic acid sufficed, suggested the need for general base catalysis as well. Thus, a mixture of triethylamine and benzoic acid proved optimal (ee's 93-99). Employment of the (/?,/?)-phenyl Trost ligand gave a product with S configuration. A model to rationalize the results has been developed.

Journal ArticleDOI
TL;DR: In this paper, a new application of pyrolytic methylation was developed to determine benzoic acid in soft drinks by gas chromatography (GC) without using any pretreatment procedures and special pyprolyzer.

Journal ArticleDOI
TL;DR: Cellular changes in the roots of mustard grown in soil treated with 1.09, 1.46 and 1.83 mg benzoic acid per g soil were analyzed and damage to the mustard root at cellular level was evidenced by changes in cell morphology and internal organization.