GB804612A - Process for the oxidation of organic compounds - Google Patents

Abstract

Alkyl aromatic compounds or their closely related oxygen-containing derivatives are oxidized to compounds containing carboxylic groups by means of molecular oxygen or ozone in the liquid phase in the presence of a catalyst of the mixed halides of at least two of the metals, manganese, cobalt and lead. The reaction preferably takes place in the presence of such solvents as lower aliphatic carboxylic acids, aromatic hydrocarbons, halogen derivatives of benzene, such as ortho-dichlor-benzene, aromatic acids and water. Suitable proportions of the catalytic substances are from 1 to 0.0005 gm. atom of total metal per gramme mol. of starting material, and preferred catalysts are the mixed bromides of cobalt and manganese, cobalt and lead, or lead and manganese. The process may be applied to the following classes of compounds: (1) alkyl aromatic hydrocarbons or alkyl heterocyclic compounds of aromatic character; (2) aromatic hydrocarbons containing at least one partially oxidized residue of an alkyl group, e.g. carboxylic, aldehyde, keto or alcohol; (3) a direct derivative, e.g. an ester of the previous compounds; (4) other aromatic compounds containing oxygen in at least one aliphatic chain, e.g. a hydroperoxide. The starting compound may contain 1, 2, or 3 alkyl groups or residues thereof, e.g. mono, di or tri alkyl benzenes. Examples are given of the following oxidations para-di-isopropyl benzene dissolved in propionic acid to terephthalic acid, para-xylene in propionic acid to terephthalic acid, para-toluic acid in propionic acid to terephthalic acid, ortho-xylene in propionic acid to orthophthalic acid, meta-xylene in propionic acid to isophthalic acid, tertiary butyl benzene in propionic acid to benzoic acid, para xylene to p-toluic acid and terephthalic acid, a mixture of p-xylene, p-toluic acid in ortho dichlorobenzene to terephthalic acid, p-xylene in benzoic acid to terephthalic acid, mesitylene in propionic acid to trimesic acid, acetophenone in propionic acid to benzoic acid, p-tertiary butyl toluene in propionic acid to p-tertiary butyl benzoic acid. The invention can also be applied to the oxidation of toluene or cumene to benzoic acid, methyl naphthalene to naphthoic acid, methyl pyridines to pyridinic acids, benzyl benzoate to benzoic acid, methyl para toluate to methyl hydrogen terephthalate and benzaldehyde to benzoic acid. The catalyst may be produced in situ by using salts of the metals which are soluble in the reaction mixture, e.g. the acetates or naphthenates, and introducing halogen, e.g. bromine or hydrobromic acid or an alkali metal bromide such as sodium, e.g. bromine may be introduced in the oxygen stream. The catalytic metal may also be introduced as Raney type, carbonyl or oxide. Chlorides and iodides may also be used, and during the reaction the halogen lost may be replaced by introducing hydrogen halide, the halogen itself, or a halogeno derivative of the aromatic starting material. Oxygen produced in situ e.g. by the decomposition of e.g. hydrogen peroxide, may be used. The reaction may be carried out at temperatures up to 300 DEG C. and pressures up to 200 atmospheres.