The Oxidation of o-Xylene and o-Toluic Acid with Co(II)-Ce(III) Bromide Ions Catalyst in Acetic Anhydride

Abstract

The catalyst composed of Co (II), Ce (III) and the bromide ions showed the highest activity for the oxidation of o-xylene in acetic anhydride (Fig.1). The optimum conditions for the catalyst were surveyed (Figs 2-5). The oxidation of o-toluic acid and o-xylene under vario u s conditions (Table 1) revealed that the composition of the products was influenced by th e con centration of the substrates. The selectivity for phthalic anhydride over 3-acetoxyphthalid e increased with the decreasing concentration of o-toluic acid (Fig.7), o-xy l e ne (Fig.8), or phthalide (Table 1). The reactivities of o-toluic acid (Fig, 9) and o-xylene (Fig, 10) in the mixed solvents of acetic acid and anhydride were also studied. The increased rate and t h e extent of oxidation were observed when 25 vol% of acetic anhydride in acetic acid was employed.
o-Toluic anhydride (Fig.11), phthalide and 3-acetoxyphthalide (Table 1) which were consi dered as intermediates for the oxidation of o-toluic acid (Fig.6) were separately oxidized in acetic anhydride and the main oxidation path of o-toluic acid in acetic anhydride was show n as in Scheme 1.