A process for producing a purified carboxylic acid having "n+1" carbon
atoms comprises feeding a carboxylic acid stream containing a carboxylic
acid having "n+1" carbon atoms, a hydrogen halide, a lower boiling point
(bp) component, a higher bp component, and others to a first distillation
column; separating a lower bp fraction containing part of the lower bp
component and a higher bp fraction containing part of the higher bp
component in the first column; withdrawing a side stream containing at
least the carboxylic acid by side cut from the first column; feeding the
side stream to a second distillation column; separating a lower bp
fraction containing part of the lower bp component and a higher bp
fraction containing part of the higher bp component in the second column;
and withdrawing a side stream containing the carboxylic acid by side cut
from the second column to recover a purified carboxylic acid; and the
process further comprises feeding 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 column, and if necessary water.
Such a process ensures reduction of the concentration of the hydrogen
halide in the purified carboxylic acid.