Azeotropic dehydration distillation process

In an azeotropic distillation process for removing water from a mixture containing water and an organic compound to be dehydrated comprising the steps of

• feeding said mixture to an azeotropic distillation column containing an entrainer having a greater affinity for said organic compound to be dehydrated than for water, whereby said mixture contacts said entrainer,
• reboiling said azeotropic distillation column to volatilize said water and said entrainer to remove said water and said entrainer from said organic compound, and
• recovering the dehydrated, entrainer-free organic compound, the improvement wherein
• said entrainer is an organic compound characterized in that
• it contains at least one fluorine atom, and at least one halogen atom other than a fluorine,
• it is miscible, under process conditions, with said organic compound being dehydrated,
• its volatility is sufficiently close to the volatility of said organic compound being dehydrated, such that, under said process conditions, it forms an azeotrope with said organic compound being dehydrated,
• it is less miscible with water than is the corresponding organic compound in which said one or more halogen atoms are replaced with hydrogen atoms, under process conditions, and
• it is chemically stable under said process conditions.