Benzoic Acid → Benzoic anhydride

Participants

Reaction Steps

1,000 g of a distillate prepared as described above (74.2% of benzyl benzoate, 13.4% of benzoic acid and 10.0% of phenylbenzoic acid) are chlorinated at 160° C. under irradiation with UV light (mercury vapour lamp). After 5 hours, the mixture has increased in weight by approx. 260 g by absorption of chlorine. 330 g of benzotrichloride and 1,1 g of FeCl3 are added dropwise to the mixture at 150° C. to convert benzoic acid which is still present and benzoic acid anhydride which has been formed into benzoyl chloride. After the evolution of hydrogen chloride has ended, the mixture is fractionally distilled in vacuo. 1,265 g of pure benzoyl chloride (yield greater than 92%, relative to benzoic acid, benzyl benzoate, phenylbenzoic acid and benzotrichloride added) are obtained in this distillation. 250 g remain in the distillation residue.

Provenance & Evidence