Process for producing acetic acid

A process for producing acetic acid, comprising the steps of:

• distilling a mixture containing at least one permanganate reducing compound (PRC), methyl iodide, water, methyl acetate, and acetic acid to separate the mixture into a first overhead and an acetic acid stream, the first overhead containing at least one PRC, methyl iodide, and water, and the acetic acid stream containing product acetic acid;
• distilling at least a portion of the first overhead as a first mixture in a distillation column to separate the first mixture into an upper stream and a lower stream, the upper stream being at least one stream selected from the group consisting of an overhead stream and a side-cut stream,
• wherein the first mixture is fed to a feed port of the distillation column, and the distillation of the first mixture allows at least a portion of water in the first mixture to rise to an upper position than the feed port of the first mixture to form a second mixture containing the portion of water;
• withdrawing the second mixture as the upper stream;
• biphasically separating the withdrawn upper stream into an aqueous phase containing at least acetaldehyde and an organic phase containing at least methyl iodide;
• and
• withdrawing a lower stream from a lower position than the feed port, wherein the lower stream has a water content lower than that of the first overhead,
• wherein the first mixture is separated into the upper stream and the lower stream without supply of additional water to the distillation column, and
• the distillation of the first mixture comprises at least one of the following (A) and (B):
• (A) the lower stream has a ratio of water relative to methyl iodide lower than the first mixture, and
• (B) not less than 1% by weight of water in the first mixture is transferred or distributed to the upper stream, and not more than 99% by weight of water in the first mixture is transferred or distributed to the lower stream.