Dihydroxybenzoic acids substituted

Ginkgo extract has no effect on the hepatic microsomal drug oxidation system, as measured by antipyrine elimination, even at doses of 400 mg per day (Duche et al. 1989). Ginkgo metabolites, the substituted benzoic acids (4-hydroxybenzoic acid conjugate, 4-hydroxyhippuric acid, 3-methoxy-4-hydroxyhippuric acid, 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, hippuric acid and 3-methoxy-4-hydroxybenzoic acid [vanillic acid]), are excreted in urine (Pietta et al. 1997). 

Several substituted dihydroxybenzoic acids have been examined by the yeast oedema and granuloma pellet test in rats , and anti-inflammatory activity appears to be restricted to the substituted 2,6-dihydroxy compounds. The presence of a halogen at Cg and Cj produces activity which is further increased when a methyl or benzyl group is also present at G4. 4-Benzyl-2,6-dihydroxybenzoic acid is also active, despite the absence of halogen at Cg or C5. The most potent compound of all is 3,5-dichloro-2,6-dihydroxy-4-methylbenzoic acid XIII). Whenever anti-inflammatory activity has been... 

In this series, as with the substituted dihydroxybenzoic acids, toxicity and activity cannot be divorced. 

Substitution of an hydroxyl group in 3,5-dihydroxybenzoic acid can be achieved by heating with ammonium chloride and 28% aqueous ammonia in an autoclave at 180 C for 40hours. Following concentration and esterification of the residue by refluxing for 36 hours with methanol containing sulphuric acid a 75% yield of methyl... 

The oxidation of substituted o-diphenols to the corresponding o-benzoquinones in the presence of 4 different binuclear copper complexes has been investigated by Bolus and Vigee [14]. The initial rates of oxidation were within a factor of 4 for the substrates catechol, 4-methylcatechol, dopamine, 3,4-dihydroxybenzoic acid, and 3,4-dihydroxybenzonitrile. The ligands of the catalyst complexes were Schiff-base type derivatives of 2,6-diformyI-4-methylphenol with diamines and amino acids their synthesis and characterization have been reported [15]. 

Habibi D, Nematollahi D, Meshldnghalam S, Varmaghani E (2014) An unexpected oxidative decarboxylation reaction of 2,3-dihydroxybenzoic acid in the synthesis of new dibenzylte-trahydroquinoxalinediones. Tetrahedron 70 4361-4366. doi 10.1016/j.teL2014.04.077 Haddadin MJ, Issidorides CH (1976) Application of benzolurazan oxide to the synthesis of heteroaromatic A-oxides. Heterocycles 4(4) 767-816. doi 10.3987/R-1976-04-0767 Haddadin MJ, Agopian G, Issidorides CH (1971) Synthesis and photolysis of some substituted quinoxaline di-A-oxides. J Org Chem 36(4) 514-518. doi 10.1021/jo00803a005 Haddadin MJ, Bitar H, Issidorides CH (1979) Synthesis and some reactions of o-nitrosoaniline. 

The benzoylation of resorcinol to produce 2,4-dihydroxybenzo-phenone has been previously performed with benzotrichloride, which implies the coproduction of 3 mol of hydrochloric acid and consequently a large amounts of acid waste. " Alternative routes to 2,4-dihydroxyben-zophenone involve direct acylation of resorcinol with benzoyl chloride (BC) or the Hoesch reaction with benzonitrile, which also suffer from acid waste production. In a more ecoefficient approach, the reaction was performed with benzoic acid (BAC) in the presence of some solid catalysts, with a special focus on BEA zeolite (Scheme 5.9). The progress of the reaction in para-chlorotoluene is examined, and after 18 h, 2,4-dihy-droxybenzophenone (2,4-DHB) is isolated in 70% yield, together with 20% of resorcinol monobenzoate (RMB), 3% of resorcinol dibenzoate, 5% of BAC, and 2% of resorcinol. The fact that the concentration of resorcinol in the final mixture is somewhat lower than that of BAC is probably due to the preferred adsorption of the former. The process is then studied by using different substituted BACs the different conversions of 2-methyl-,... 

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