| 摘要 |
<p>Aromatic carboxylic acids are obtained by oxidising a methyl-substituted aromatic compound (which may be a heterocyclic compound) in the liquid phase and at atmospheric pressure with molecular oxygen in the presence of an oxidation catalyst and an ether, which acts as a promoter. The ether must have at least one a -hydrogen atom but otherwise may be an alkyl, aryl, alkaryl, aralkyl or alkoxyalkyl ether. Specified ethers are dibenzyl ether, diisopropyl ether, di-n-butyl ether, dimethoxymethyl ether and the dibutyl ether of ethylene glycol. The ether is used in a proportion of 0.1-10 parts by weight per part of aromatic compound. Specified oxidation catalysts are heavy-metal phthalocyanines or porphorazines, e.g. iron or cobalt phthalocyanine, and metal salts of carboxylic acids, e.g. cobaltous naphthenate or acetate or manganese acetate. The oxidation may be effected with oxygen, air or other oxygen-containing gas, the quantity of gas (calculated as oxygen) being about 0.1-4 c.ft. per hour per 100 grams of aromatic compound. The reaction temperature lies between 50 DEG C. and the boiling point of the aromatic compound under atmospheric pressure, and the reaction period may be 0.5-10 hours. Examples are given of the oxidation of toluene, p-xylene, mesitylene and p-toluic acid. Other specified compounds which may be treated are o- and m-xylene, hemimellitene, pseudocumene, a - and b -methylnaphthalene, dimethylnaphthalene, o- and m-toluic acids, xylic acid, 5-methylisophthalic acid, mesitylenic acid, methylpyridine, tolunitrile and p-chlorotoluene. Phenyl benzyl ketone is obtained as a by-product when toluene is oxidized in the presende of dibenzyl ether.</p> |
