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A Green approach to the oxidation of some industrially important alcohols using Ammonium meta vanadate in mildly acidic medium

D V Prabhu 

Toxic and expensive metals like Osmium,Chromium and Rutheniumin different oxidation states have been exhaustivelyused as catalysts for organic reactions.The use of these metals ishazardous to the environment and hence should be reduced asfar as possible.We have successfully used less toxic and cheapertransition metal ions of the first series to catalyze the oxidationof some industrially important alcohols by Ammonium metavanadate under mildly acidic conditions.Some of the alcohols oxidized are:1)Acyclic alcohols –The primary alcohols, Nerol,Citronelloland Geraniol are used in the preparation of perfumes.2) Cyclic alcohols-The secondary alcohols, Cyclopentanol.Cyclohexanoland Cyclooctanol are used in the manufacture ofpolymers,plasticizers and pharmaceuticals.3)Substituted ethanols-2-Chloroethanol,2-Butoxyethanol and2-Phenoxyethanol are used in the preparation of varnishes,cropprotection chemicals and industrial cleaners.The oxidation was studied under first order kinetic conditionswith respect to the inorganic oxidant and the progress of oxidationwas monitored iodometrically.From the variation of oxidationrate with temperature (303-313K), the thermodynamicalactivation parameters of the oxidation process were evaluatedand interpreted.The sequences of oxidation rates of alcoholshas been explained on the basis of theirsteric,isomeric and structural characteristics.Transition metal ions ,Mn(II),Co(II) and Ni(II) have been usedto catalyze the oxidation of alcohols.For each alcohol understudy ,the sequence of catalytic efficiencies of the metal ion catalystshas been determined. The oxidation rates of all alcoholsstudied varied linearly with the metal ion catalyst concentration.A suitable reaction mechanism has been suggested for the oxidationof alcohols using Ammonium meta vanadate in acidicmedium.