Benzoic acid

About: Benzoic acid is a research topic. Over the lifetime, 11832 publications have been published within this topic receiving 167127 citations. The topic is also known as: Retardex & E210.

Inhibition by carboxylic acids of an o‐diphenol oxidase from Prunus avium fruits

Abstract: Aromatic carboxylic acids strongly inhibited 4-methylcatechol oxidation by an o-diphenol oxidase extracted from sweet cherry fruits (Prunus avium). Esterification of the acids decreased their inhibitory strength. Inhibitors containing the benzene nucleus showed a greater effectiveness than the corresponding aliphatic and heterocyclic compounds (except 2-naphthalenecarboxylic acid). Similar inhibitory effects were observed by replacing the benzene ring with a highly unsaturated open chain. The inhibitory properties of benzoic acid, cinnamic acid, p-coumaric acid and 3,4-dihydroxybenzoic acid were investigated. It is proposed that the catalytic and inhibitory sites are close together in the enzyme molecule.

Polymer-anchored vanadium(IV), molybdenum(VI) and copper(II) complexes of bidentate ligand as catalyst for the liquid phase oxidation of organic substrates

Abstract: Monobasic bidentate ligand 2-(2′-hydroxyphenyl)benzimidazole (Hhpbmz) has been covalently bonded to the chloromethylated polystyrene cross-linked with 5% divinylbenzene. Treatment of the resulted chelating resin, abbreviated as PS-Hhpbmz, with [VO(acac)2], [MoO2(acac)2] (Hacac = acetylacetone) and Cu(CH3COO)2·H2O, gave polymer-anchored complexes PS-[VO(hpbmz)2], PS-[MoO2(hpbmz)2] and PS-[Cu(hpbmz)2], respectively. The corresponding neat complexes with Hhpbmz have also been prepared similarly. Structures of these complexes have been established on the basis of elemental analyses, scanning electron micrographs and spectroscopic (infrared and electronic) as well as thermogravimetric studies. These complexes have been tested as catalyst for the oxidation of styrene, ethylbenzene and methyl phenyl sulfide. Reaction conditions for the maximum oxidation of these substrates have been optimised by considering the concentration of oxidant, amount of catalyst, volume of solvent and temperature of the reaction mixture. Under the optimised conditions styrene gave a maximum of 58.9% conversion with five reaction products namely styrene oxide, benzaldehyde, 1-phenylethane-1,2-diol, benzoic acid, and phenylacetaldehyde. Oxidation of ethylbenzene gave 47.7% conversion where benzaldehyde, phenyl acetic acid, styrene, 1-phenylethane-1,2-diol and benzoic acid have been obtained as major oxidation products. A maximum of 76.5% conversion of methyl phenyl sulfide, catalysed by PS-[VO(hpbmz)2], has been achieved. Catalyst, PS-[MoO2(hpbmz)2] has shown comparable (75.1%) catalytic activity while only 44.8% conversion has been achieved with PS-[Cu(hpbmz)2]. Irrespective of their catalytic performances, the selectivity for the formation of sulfoxide is almost similar (ca. 75%) for all these catalysts. These catalysts do not leach metal ions during catalytic activity and are recyclable.

Direct fries reaction of resorcinol with benzoic acids catalyzed by zeolite H-beta

Abstract: The esterification reaction of resorcinol with benzoic acid, followed by the Fries rearrangement towards benzophenones in a one-pot liquid phase operation was examined with several catalysts. Zeolite H-beta and ion-exchange resins (Amberlyst-15, Nafion-117) were found to be the best catalysts for both equilibrium reactions. More insight in the Fries rearrangement was obtained by carrying out the reaction with a series of substituted phenols and substituted benzoic acids, especially with zeolite H-beta as the catalyst. The esterification reaction of resorcinol with hindered benzoic acids (2-Me- and 2,6-diMe-benzoic acid) is relatively rapid and an intermediate acylium ion is suggested. Here the rate of the rearrangement to the benzophenones is catalyst dependent; with zeolite H-beta the rearrangement of resorcinol-2-Me-benzoate is fast (yield > 90%) and the rearrangement of resorcinol-2,6-diMe-benzoate is slow because of the pore dimensions of the zeolite (shape effect). With Amberlyst-15 as the catalyst both rearrangements are fast. n-Butylbenzene, p -Cl-toluene and n-decane are found to be good solvents in this one-pot reaction. The industrial chemical 2,4-dihydroxybenzophenone can be prepared in a 88% yield by a recycling procedure starting from benzoic acid and resorcinol with zeolite H-beta as the catalyst and with n-butylbenzene as the solvent. In contrast to the existing process the present approach is a clean method.