Preparation of polycarboxylic acids by oxidative cleavage with oxygen / Co-Mn-Br system.

Adipic acid and glutaric acid were obtained from 1-hydroxy-2- acetoxycyclohexane by oxidation cleavage using molecular oxygen in the presence of cobalt acetate, manganese acetate and hydrobromic acid in acetic acid solution. Applying this method to prepare dicarboxylic acids from unsaturated fatty acids, we proposed an efficient method where reaction mixture of unsaturated fatty acids and hydrogen peroxide - formic acid can be oxidative cleaved to produce dicarboxylic acids and monocarboxylic acids in acetic acid solution with molecular oxygen / Co-Mn-Br system. For example, azelaic acid, suberic acid and other dicarboxylic acid as dicarboxylic acids were obtained from industrial oleic acid, which contained oleic acid, palmitoleic acid, linoleic acid, and linolenic acid. As a result of investigation for reaction condition, increase of partial pressure of molecular oxygen or elevation of temperature accelerated oxidative cleavage, but total yields of azelaic acid and suberic acid were slightly decreased. Besides, effect of hydrohalic acids in liquid phase air oxidation in the presence of cobalt and manganese acetates was investigated to show that HBr was the most effective. Soybean acid and tall acid containing higher amounts of linoleic acid and linolenic acid than industrial oleic acid were also oxidatively cleaved to dicarboxylic acids.