Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
1999-07-21
2001-06-26
Killos, Paul J. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
Reexamination Certificate
active
06252115
ABSTRACT:
The present invention relates to a process for distillative separation of part or all of an imine (III) from a mixture (II) comprising an amine (I) and said imine (III), which comprises adding to the distillation mixture a compound (IV) which is inert toward said amine (I) under distillation conditions and whose boiling point is above the boiling point of said amine (I) under said distillation conditions to obtain, after the distillation, a mixture (VI) comprising essentially said compound (IV).
Mixtures comprising an amine and an imine are customarily obtained in the hydrogenation of nitriles to amines.
The complete hydrogenation of adiponitrile to hexamethylenediamine, and also the partial hydrogenation with coproduction of hexamethylenediamine and 6-aminocapronitrile, in the presence of a catalyst based on a metal such as nickel, cobalt, iron, rhodium or ruthenium, is generally known, for example from: K. Weissermel, H.-J. Arpe, Industrielle Organische Chemie, 3rd Edition, VCH Verlagsgesellschaft mbH, Weinheim, 1988, page 266, U.S. Pat. Nos. 4,601,859, 2,762,835, 2,208,598, DE-A 848 654, DE-A 954 416, DE-A 42 35 466, U.S. Pat. No. 3,696,153, DE-A 19500222, WO 92/21650 and German Application 19548289.1.
By-products include imines such as aminohexylideneimine and tetrahydroazepine.
These imines, which, because of their color and deleterious effects on product properties, are undesirable impurities in the amines, which are customarily used for producing synthetic fibers, are difficult to separate from the amines.
For instance, GB-A-893 709 discloses installing a delay time vessel in the reflux line of a distillation column used for purifying hexamethylenediamine.
GB-A-1 238 351 describes the separation of hexamethylenediamine from mixtures comprising hexamethylenediamine and imines by addition of alkali metal hydroxide mixtures.
GB-A-1 041 442 discloses passing carbon dioxide into a distillation column used for separating hexamethylenediamine from mixtures comprising hexamethylenediamine and imines, during the distillation.
Disadvantages with the processes mentioned are the use of large vessels, which makes for reduced control of the distillation columns, and the formation of solids, which can lead to blockages.
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J. Arpe, Ind. Org. chem, Weissermel, 1986, 266.
Bassler Peter
Luyken Hermann
Rehfinger Alwin
BASF - Aktiengesellschaft
Keil & Weinkauf
Killos Paul J.
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