Vanillin is a phenolic aldehyde, which is an organic compound including aldehyde, hydroxyl and ether. It is the primary component of the extract of the vanilla bean. Vanillin is a significant flavoring reagent in the industry of food and is widely used in the production of drugs. It has been also used as a chemical intermediate in the preparation of pharmaceuticals and other fine chemicals. Furthermore, it is used in the synthesis of perfume and as a catalyst in various polymerization reactions. When the hydroxyl group in vanillin molecule is protected, vanillin is oxidized to vanillic acid. Kinetics of oxidation of vanillin has been studied previously in alkaline solutions by different reagents, as hexacyanoferrate(III), diperiodatoargentate(III), bismuth(V), diperiodatonickelate(IV) and periodate catalyzed by ruthenium(III), and in acid media by cerium(IV).
Oxidation reactions are very important in nature and in organic synthesis. Among the most important oxidants is chromium(VI) which may play a significant role in the chemistry of vanillin in the environment due to the mutagenic and carcinogenic activity of chromium. Chromium exists in both trivalent, Cr(III), and hexavalent, Cr(VI), species in aqueous solutions and the two oxidation states are identified by various physical/chemical behavior and toxicity. Chromium(VI) compounds are very dangerous for biological systems, but those of chromium(III) are relatively non-toxic. Chromium(VI) is employed for oxidation of organic compounds and it is reduced to lower oxidation state. The chemistry of Cr(V) and Cr(IV) as intermediate species which may be formed during reduction of chromium(VI) were attracted many researchers because of their involvement in the mechanism of Cr–induced cancers.
A literature survey revealed that various literature are available on the kinetics of chromium(VI) oxidations of different inorganic and organic substrates, whereas there is no available reports on the oxidation of the vanillin by this oxidant. Owing to the above arguments, the title reaction has been studied. The objectives of the present investigation are to explore the selectivity of vanillin towards chromium(VI), to identify the oxidation products of vanillin and to suggest a suitable oxidation mechanism.
A literature survey revealed that various literature are available on the kinetics of chromium(VI) oxidations of different inorganic and organic substrates, whereas there is no available reports on the oxidation of the vanillin by this oxidant. Owing to the above arguments, the title reaction has been studied. The objectives of the present investigation are to explore the selectivity of vanillin towards chromium(VI), to identify the oxidation products of vanillin and to suggest a suitable oxidation mechanism.
No comments:
Post a Comment