An alkali-metal benzoate is prepared besides benzyl alcohol from a contaminated benzyl benzoate reaction residue obtained in the oxidation of a monoalkyl-benzene compound with a gas containing molecular oxygen. The disclosed process provides for distillation of the contaminated benzyl benzoate in the presence of a basic substance and the resulting distillate is hydrolyzed using an alkali-metal base. In this way, the benzyl benzoate that previously could not be separated from certain tar components by distillation is converted into a pure alkali metal benzoate such as sodium benzoate, besides pure benzyl alcohol, so that a waste product that was previously useless is converted into useful substances.
High-purity benzyl benzoate is recovered by distilling the residue remaining after removal of unreacted toluene and benzoic acid from a reaction mixture produced by the oxidation of toluene by molecular oxygen in the presence of a metal catalyst thereby separating a fraction of benzyl benzoate containing 80 wt % or more benzyl benzoate, 10 wt % or less benzoic acid and 10 wt % or less fluorenone, and purifying the fraction of benzyl benzoate by crystallization such as recrystallization. According to this process, it is possible to recover high-purity benzyl benzoate by a simple operation at low cost from the by-product formed in the manufacture of benzoic acid.
Process for the preparation of benzyl alcohol via hydrolysis of a benzyl ester with water in the liquid phase, the hydrolysis being carried out in the absence of a strong acid and a base at a temperature between 40.degree. C. and 320.degree. C. The benzyl ester to be hydrolyzed can be chosen from the group comprising benzyl formiate, benzyl propionate, benzyl acetate and benzyl benzoate. A weak acid may optionally be added to the reaction mixture to be hydrolyzed. After the hydrolysis the reaction mixture is preferably cooled to a temperature between 80.degree. C. and 180.degree. C. so that a phase separation takes place. Both the organic phase and the aqueous phase can be upgraded. As such, benzyl alcohol can be obtained with a high overall yield and a purity of more than 98%.
The invention relates to a method for the purification of benzoic acid, which is obtainable through oxidation of the corresponding toluene derivative, by treating it with a --NH.sub.2 or --NHR containing component in which R represents a carbon containing group, said component being applied to a support.
