Patent ID: 7678940

Claim:
A process for producing a carboxylic acid having “n+1” carbon atoms, which comprises feeding a carboxylic acid stream containing at least a carboxylic acid having “n+1” carbon atoms, a hydrogen halide, a lower boiling point component and a higher boiling point component to a first distillation column, separating a first lower boiling point fraction containing part of the lower boiling point component and a first higher boiling point fraction containing part of the higher boiling point component in the first distillation column, withdrawing a first side stream containing at least the carboxylic acid having “n+1” carbon atoms by side cut from the first distillation column, feeding the first side stream to a second distillation column, separating a second lower boiling point fraction containing part of the lower boiling point component and a second higher boiling point fraction containing part of the higher boiling point component in the second distillation column, and withdrawing a second side stream containing the carboxylic acid having “n+1” carbon atoms by side cut from the second distillation column to recover a carboxylic acid having “n+1” carbon atoms; which further comprises feeding (i) water and at least one first component (A) selected from the group consisting of an alcohol, corresponding to the carboxylic acid, having “n” carbon atom(s), and an ester of the alcohol with the carboxylic acid to the first distillation column, or (ii) at least one first component (A) selected from the group consisting of an alcohol, corresponding to the carboxylic acid, having “n” carbon atom(s), and an ester of the alcohol with the carboxylic acid to the first distillation column from a lower position relative to a first side stream port for conducting side cut of the first side stream containing the carboxylic acid having “n+1” carbon atoms.