Aerial oxidation of substituted aromatic hydrocarbons catalyzed by Co/Mn/Br in water-dioxane medium

Abstract

Aerial oxidation of substituted aryl aromatic hydrocarbons were carried out using Co/Mn/Br catalyst system in water-dioxane medium in the range 14–56 bar air and temperature 383–423 K. The combination of optimum catalyst concentration of salts Co(OAc)2, Mn(OAc)2 and NaBr (1:3:10 molar ratio) in water-dioxane (1:2 mole ratio) is found catalyze aerial oxidation of substituted aryl aromatic to give corresponding oxygenated products. Under the optimized conditions, p-cymene gave p-isopropyl benzaldehyde (33.1%), p-isopropylbenzyl alcohol (54.7%) and p-isopropyl benzoic acid (3.3%), respectively, at p-cymene conversion 40.2%. Similarly, oxidation of p-methoxy toluene gave p-methoxy benzaldehyde (87.4%), benzyl alcohol (5.5%), and p-methoxy benzoic acid (6%), while oxidation of p-tert-butyl toluene yielded p-tert-butyl benzaldehyde (87%), p-tert-butyl benzyl alcohol (5.7%) and p-tert-butyl benzoic acid (6.1%), at conversions 16.4% and 36.1%, respectively. It is found that o/Mn/Brcatalyst system in water-dioxane medium is effective in the aerial oxidation of substituted aromatic hydrocarbons to get corresponding alcohol and aldehydes in greater yields.