Benzene → Phthalic Anhydride

Participants

Reaction Steps

Decarboxylation is not always a predictable reaction. For example, A. S. Sultanov, J. Gen. Chem. (USSR) 16 1835 (1946) as abstracted in CA 41:6223(e) discloses that salicylic acid may be decarboxylated by autoclaving the acid in the presence of copper bronze and benzene at 170° C. The acid alone decarboxylates at 205° C., while in the presence of aniline decarboxylation begins at 170° C. In the case of salicylic acid, aniline and copper bronze seem to be equal in catalytic ability. On the other hand, when phthalic acid is heated in aniline at 180° C., decarboxylation does not occur and instead phthalic anhydride is produced. Heating phthalic anhydride with copper bronze in chloroform at 180° C. gave a 22% yield of benzoic acid. Phthalic acid was found to decarboxylate to yield benzoic acid merely by heating in water at 235° C.

Provenance & Evidence