3base
(Newbee) 06-04-02 09:03 No 317536 |
benzaldehydes from benzoic acids | Bookmark | ||||||
this thread is dedicated to the direct conversion of benzoic acid derivatives to the corresponding benzaldehydes |
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3base (Newbee) 06-04-02 09:05 No 317538 |
vanillic acid --> vanillin | Bookmark | ||||||
vanillic acid --> vanillin electroreduction j org chem, 1972 37(10), 1513-6 "the electrochemical reduction of aromatic acids to the corresponding aldehydes"; john h wagenknecht abstract: a number of aromatic carboxylic acids have been found to undergo electrochemical reduction of aromatic acids to the corresponding aldehydes. electrondonating substituents in the para position inhibit the reaction. it is possible to predict from the pKa value of the acid or, more accurately, from the polarographic half-wave potential of the corresponding methyl ester whether or not the method is applicable for the preparation of an aldehyde. |
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3base (Newbee) 06-04-02 09:08 No 317539 |
benzoic acid --> benzaldehyde | Bookmark | ||||||
benzoic acid --> benzaldehyde calcium benzoate, formic acid, calcium formate (1) justus liebigs ann chem, 1856 100, 105; piria (2) jahresber fortschr chem verw theile anderer wiss, 1856, 431 benzoic acid --> benzaldehyde vacuum ultraviolet irradiation journal of physical organic chemistry, 2001 14(5), 300-309 "reactions of carbon dioxide radical anion with substituted benzenes" janina a rosso, sonia g bertolotti, andré m braun, daniel o mártire, mónica c gonzalez abstract: we report mechanistic studies on the reactivity of CO2.- radicals towards substituted benzenes, XPh, with X = NO2, COOH, COH, CH3, H, Cl and HO. vacuum ultraviolet (VUV, 172 nm) irradiation of aqueous solutions containing formate was used as a method of CO2.- radical generation for the study of the reaction products, which were determined by gas chromatography- mass spectrometry and high-performance liquid chromatography. the nature of some of the reaction intermediates was studied by laser flash photolysis of aqueous solutions of peroxodisulfate in the presence of formate. the observed products and intermediates of reaction are discussed and rationalized by a dual reactivity of the CO2.- radical anion with substituted benzenes: a one- electron reduction and radical addition to the aromatic ring. for substituted benzenes with X = NO2, COOH and COH, the observed products support an electron transfer from CO2.- to the substrates as the primary reaction channel, while the reactions with toluene follow the channel of radical addition. benzene and chlorobenzene react with CO2.- by both routes, electron transfer and radical addition. our experimental results indicate that H abstraction by the CO2.- radical is negligible under the chosen experimental conditions. |
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