Preparation of purified concentrated BDO

A process of purifying crude 1,4-butanediol to purified concentrated 1,4-butanediol, said crude butanediol containing about 1 to about 30% by weight of water and organic impurities that boil lower than 1,4-butanediol, about 0.05 to about 5% by weight of high boiling organic compounds and inorganic and organic salts, and about 70 to 99% by weight of 1,4-butanediol, which consisting essentically of:

• fractionating said crude butanediol feed stream at a temperature of no more than 210.degree. C. into a purified concentrated 1,4-butanediol fraction and a bottom fraction;
• separating as bottoms a fraction having a weight of not greater than 6% of the weight of said feed stream, said bottoms fraction containing high boiling organic compounds, inorganic and organic salts and not more than 60% by weight of 1,4-butanediol, and
• separating as overhead said purified concentrated 1,4-butanediol fraction which contains about the same amount of water as, and less high boiling organic compounds and inorganic and organic salts than, were in said crude butanediol feed stream, the amount of said high boiling organic compounds and said salts in said overhead fraction being not more than 0.1% by weight, based on the total organics.