Author: D.V.Prabhu, Chetana Rana

DOI:

Several organic oxidants have been used for the oxidation of alcohols to the corresponding carbonyl compounds but inorganic oxidants have rarely been used. The quantitative conversion of alcohols to aldehydes /ketones has been extensively studied but there are few reports of the kinetic investigations of the oxidation of alcohols. The present paper discusses the kinetics of oxidation of 1-hexanol and cyclohexanol using potassium persulphate (K₂S₂O₈) and potassium periodate (KIO₄) in acidic medium. 1-hexanol is used in the perfumery industry and cyclohexanol in the manufacture of polymers. Cyclohexanol has an important application as a precursor to nylon. The oxidation was studied under first order kinetic conditions with respect to the oxidant. The progress of the oxidation was monitored by titrimetric estimation of the unreacted oxidants at regular time intervals during the course of the reaction. For both the alcohols, the oxidation rate increased with alcohol concentration but decreased with oxidant concentration.  The oxidation rates followed the sequence: 1-hexanol >cyclohexanol.    Potassium persulphate was found to be a stronger oxidising agent than potassium periodate for the alcohols under study. The reaction was found to be independent of ionic strength (µ). From the effect of temperature (303-318K) on the rate of oxidation, the various thermodynamic parameters were determined and interpreted in terms of the molecular dynamics of the oxidation process. Suitable reaction mechanisms have been suggested for the oxidation of the alcohols.

Keywords: alcohol, inorganic oxidant, kinetics, ionic strength, energy of activation, entropy of activation, reaction mechanism.