| 摘要 |
A process for the oxidation of the aliphatic side chains of toluene or xylene to the corresponding carboxylic acids with molecular oxygen or gases containing it, such as air, is carried out in the presence of a cobalt oxide catalyst insoluble in the hydrocarbon to be oxidized and remaining insoluble in the reaction mixture from the beginning to the end of the oxidation. The cobalt oxide is prepared by a dry method and is preferably subjected prior to use for the first time to a treatment with boiling water for a duration of 10-180 minutes. It contains an oxygen percentage higher than that corresponding to the formula CoO and preferably an oxygen content of 25-35%. The catalyst is preferably utilized together with an inert finely divided substance. In an example toluene is oxidized in an autoclave to benzoic acid by drawing air therethrough in the presence of cobalt oxide obtained by grinding cobalt carbonate to a fine powder and passing air at 600-700 DEG C. therethrough for about 2 1/2 hours and thereafter placing the powder in water and boiling for 1 hour and filtering. In another example, para-xylene is oxidized to a mixture of toluic and terephthalic acids. In a further example, the oxidation of toluene to benzoic acid is described in conjunction with a suitable apparatus.ALSO:A cobalt oxide of a higher oxygen content than cobalt monoxide is prepared by treating metallic cobalt, cobalt oxide or hydroxide or a salt of divalent cobalt with a volatile acid, e.g. cobalt, carbonate or nitrate, with oxygen or a gas containing molecular oxygen at 200-800 DEG C., the cobalt or cobalt compound being in the dry state and no liquid medium being present. Reference is made to cobalt oxides having oxygen contents of 25-35% by weight. |
