Kinetics of Controlled Oxidation of Some Aliphatic Alcohols Using Potassium Iodate

摘要

The first-order oxidation kinetic, mechanistic and thermodynamic aspects of oxidation of several types of industrially important alcohols viz. 1-propanol, 1-butanol, 1-hexanol, isopropyl alcohol and isobutyl alcohol using an inorganic oxidant potassium iodate are reported in this article, Iodometric estimation of the unreacted oxidant at regular intervals during the reaction course was used to track reaction progress. The oxidation rate was directly and inversely related to alcohol concentration and [KIO3], respectively, in all the alcohols studied. The reaction mechanism sμggested that oxidation rates were independent of ionic strength. The oxidation rate varied with temperature. The Arrhenius equation was used to determine thermodynamic activation parameters and interpreted on the basis of the molecular dynamics of oxidation process. The reaction mechanism has been explained on the basis of the formation of halic acid (HIO3) and hypoiodite ion (lO~-) in an acidic medium. The oxidation rates follow the sequence: 1-propanol > 1-butanol > isopropyl alcohol > isobutyl alcohol > 1-hexanol, which has been explained on the basis of chain length and other structural features of the alcohols under investigation. Transition metal ions viz., Mn(ll), Co(ll), Ni(II), Zn(II), Cu(II) and Cd(II) have been used to catalyze the oxidation of the aliphatic alcohols in acidic medium and the sequences of their catalytic efficiencies has also been determined.