Process for preparing 1,6 hexanediol with a level of purity over 99%

US6008418A · kind A · utility

Assignee

• BASF SE

Inventors

• Karl Baur · Baierbrunn, DE
• Rolf Fischer · Heidelberg, DE
• Rolf Pinkos · Bad Dürkheim, DE
• Frank Stein · Bad Dürkheim, DE
• Harald Rust · Bochum, DE
• Boris Breitscheidel · Fulda, DE

Key dates

• Filing date: Aug 28, 1998
• Grant date: Dec 28, 1999
• Expiry date: Aug 28, 2018

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C29/149
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

1,6-Hexanediol is prepared from a carboxylic acid mixture comprising adipic acid, 6-hydroxycaproic acid and small amounts of 1,4-cyclohexanediols which is obtained as a by-product in the oxidation of cyclohexane to cyclohexanone/cyclohexanol by water extraction of the reaction mixture, by esterification of the acids and hydrogenation wherein PA1 a) the monocarboxylic and dicarboxylic acids present in the aqueous dicarboxylic acid mixture are reacted with a low molecular weight alcohol to give the corresponding carboxylic esters, PA1 b) the resulting esterification mixture is freed of excess alcohol and low boilers in a first distillation stage, PA1 c) the bottoms are fractionated in a second distillation stage to give an ester fraction essentially free of 1,4-cyclohexanediols and a fraction comprising at least the major part of the 1,4-cyclohexanediols, PA1 d) the ester fraction essentially free of 1,4-cyclohexanediols is catalytically hydrogenated and PA1 e) in a pure distillation stage, 1,6-hexanediol is isolated from the hydrogenation product in a manner known per se.