B. Ramkumar*1, V. Santhosh Kumar2 and M. Rukmangathan2
*1PG and Research department of chemistry, Govt. Arts College, Thuvakudimalai, Tiruchirappalli, Tamil Nadu, India–620022
2Department of Chemistry, Arasu Engineering College, Kumbakonam, Tamil Nadu, India–612501
The kinetics of oxidation of aliphatic alcohols by 1-bromobenzimidazole (BBI) has been studied in aqueous acetic acid medium in presence of mercuric acetate. The order of the reaction with respect to [BBI] and [alcohol] are unity. The reaction is fractional order with respect to [H+]. The rate of oxidation increases with decrease in dielectric constant of solvent medium indicating ion-dipole interaction. The rate of the reaction is not influenced by the addition of electrolytes like sodium perchlorate. Polymerization was not observed with acrylonitrile. The reactions were studied at four different temperatures and thermodynamic parameters have been calculated. The oxidation of aliphatic alcohols shows a Taft ρ value of -0.722 suggesting an electron deficient transition state. BBIH+ has been postulated as the reactive oxidizing species. A suitable mechanism in consistent with the observed kinetic data is proposed.
Keywords: aliphatic alcohols, 1-bromobenzimidazole, oxidation, kinetics.