Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2007-12-11
2007-12-11
Price, Elvis O. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S852000, C568S854000, C568S864000
Reexamination Certificate
active
10580685
ABSTRACT:
The present invention provides a process for preparing 1,6-hexanediol from a carboxylic acid mixture which comprises adipic acid, 6-hydroxycaproic acid and small amounts of 1,4-cyclohexanediols and is obtained as a by-product in the oxidation of cyclohexane to cyclohexanone/cyclohexanol with oxygen or oxygen-containing gases and by water extraction of the reaction mixture, by esterification of the acids and hydrogenation, in whicha) the mono- and dicarboxylic acids present in the aqueous dicarboxylic acid mixture are reacted with a low molecular weight alcohol to give the corresponding carboxylic esters,b) the resulting esterification mixture is freed of excess alcohol and low boilers in a first distillation stage,c) a separation of the bottom product is carried out in a second distillation stage into an ester fraction substantially free of 1,4-cyclohexanediols and a fraction comprising at least the majority of the 1,4-cyclohexanediols,d) the ester fraction substantially free of 1,4-cyclohexanediols is catalytically hydrogenated ande) 1,6-hexanediol is obtained in a purifying distillation stage from the hydrogenation effluent while removing an alcohol-low boiler mixture in a manner known per se, wherein alcohol is removed by a membrane system from the mixtures, obtained after the esterification in stage b) and/or after the hydrogenation in stage e), of alcohols and low boilers and recycled into the esterification.
REFERENCES:
patent: 0 552 463 (1993-07-01), None
patent: 97/31882 (1997-09-01), None
patent: 97/31883 (1997-09-01), None
“Ullmann's Encyclopedia of Industrial Chemistry”, Fifth, Completely Revised Edition, vol. A8, p. 49 1987.
Weyl, Houben, “Methoden Der Organischen Chemie”, Band IV1c, pp. 45-67, 1980.
Weyl, Houben, “Methoden Der Organischen Chemie”, Band IV1c, pp. 16-26, 1980.
Borgel Franz
Diefenbacher Armin
Heck Ludwig E.
Krause Alfred
Sirch Tilman
BASF - Aktiengesellschaft
Price Elvis O.
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