Abstract:
PROBLEM TO BE SOLVED: To provide a method for producing hexanediol-1,6 from a carboxylic acid mixture. SOLUTION: In the method, (a) the carboxylic acids contained in an aqueous dicarboxylic acid mixture are converted to the corresponding carboxylic acid esters by using a low-molecular weight alcohol, (b) the obtained esterification mixture is separated from the excess alcohol and low-boiling point components in a first distillation stage, (c) the bottom products are fractionated in a second distillation stage into an ester fraction essentially free of 1,4-cyclohexanediol and a fraction comprising at least the major part of the 1,4-cyclohexanediol, (d) the ester fraction substantially free of 1,4-cyclohexanediol is catalytically hydrogenated, and (e) 1,6-hexanediol is obtained in a rectification stage from the hydrogenated discharge in a known manner. Thereby, high purity 1,6-hexanediol is made obtainable from waste products in a high yield. COPYRIGHT: (C)2009,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide a method for preparing 1,6-hexanediol from a carboxylic acid mixture.SOLUTION: The method for preparing 1,6-hexanediol includes processes of: (a) converting carboxylic acids contained in an aqueous dicarboxylic acid mixture to the corresponding carboxylic acid esters by using a low-molecular weight alcohol; (b) separating the obtained esterification mixture from excessive alcohol and low-boiling point components in a first distillation stage; (c) fractionating bottom products in a second distillation stage into an ester fraction essentially free of 1,4-cyclohexanediol and a fraction comprising the major part of 1,4-cyclohexanediol; (d) catalytically hydrogenating the ester fraction essentially free of 1,4-cyclohexanediol; and (e) obtaining 1,6-hexanediol in a purifying distillation stage from the hydrogenation product in a known manner. In this way, high purity 1,6-hexanediol can be obtained in a high yield from waste products.
Abstract:
Verfahren zur Herstellung von Aldehyden der allgemeinen Formel I R-CHOIdurch Hydrierung von Carbonsäureestern der allgemeinen Formel II R-COOR'II,in denen R für einen gegebenenfalls substituierten und/oder gegebenenfalls Heteroatome enthaltenden aliphatischen, cycloaliphatischen, aromatischen oder araliphatischen Rest steht und R' den Rest eines C1- bis C10-Alkohols bedeutet, bei 200 bis 450°C mit überschüssigem Wasserstoff in Mengen von 2 bis 200 mol Wasserstoff pro Mol Ester in Gegenwart eines heterogenen Hydrierkatalysators in der Gasphase unter Rückführung des nicht umgesetzten Wasserstoffs und des nicht umgesetzten Esters in die Hydrierung, dadurch gekennzeichnet, dass man die Rückführungsströme vom entstandenen Alkohol R'OH zumindest in dem Umfang befreit, dass dessen Anfangskonzentration im Reaktionsgemisch, bezogen auf den eingesetzten Carbonsäureester II, maximal 1 Mol pro Mol beträgt.