Organic compounds -- part of the class 532-570 series – Organic compounds – Unsubstituted hydrocarbyl chain between the ring and the -c-...
Patent
1998-06-16
2000-11-14
McKane, Joseph K.
Organic compounds -- part of the class 532-570 series
Organic compounds
Unsubstituted hydrocarbyl chain between the ring and the -c-...
564511, C07D20102, C07C21112
Patent
active
061472085
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the simultaneous preparation of caprolactam and hexamethylenediamine starting from adiponitrile.
The present invention furthermore relates to an improved process for the simultaneous separation of 6-aminocapronitrile and hexamethylenediamine from a mixture containing these substances. The partial hydrogenation of adiponitrile to 6-aminocapronitrile in the presence of ammonia and various catalysts has been sufficiently described. For example, U.S. Pat. No. 4,601,859 describes the use of catalysts based on rhodium on magnesium oxide, U.S. Pat. No. 2,762,835 describes the use of Raney nickel, U.S. Pat. No. 2,208,598 describes the use of nickel on alumina, DE-A 848 654 describes fixed-bed catalysts based on copper/cobalt/zinc and iron/cobalt spinels, DE-A 954 416 describes the use of cobalt on silica gel and DE-A 4 235 466 describes the use of iron sponges.
In the process described in WO 92/21650, aminocapronitrile yields of 60% at a conversion of 70% and hexamethylenediamine yields of 9% are achieved in the presence of Raney nickel. At a conversion of 80%, the yield is 62%.
It is also known that 6-aminocapronitrile can be reacted with water in the gas or liquid phase in the presence or absence of catalysts with liberation of ammonia to give caprolactam. For example, U.S. Pat. No. 2,301,964 describes a process in which from 10 to 25% strength solutions of 6-aminocapronitrile are converted in the liquid phase at from 250 to 290.degree. C. into caprolactam in yields of up to 76%.
Furthermore, the cyclization of from 25 to 35% strength 6-aminocapronitrile solutions at 220.degree. C. in the liquid phase in water with the addition of organic solvents in the presence of zinc compounds, copper compounds, lead compounds and mercury compounds is described in FR-A 2,029,540. Caprolactam yields of up to 83% are achieved here.
The cyclization of 6-aminocapronitrile can also be carried out in the gas phase (U.S. Pat. No. 2,357,484): starting from 80% strength aqueous solutions, caprolactam yields of 92% are achieved at 305.degree. C. using alumina as a catalyst.
EP-A 150 295 describes the reaction of 6-aminocapronitrile in the gas phase in the presence of copper/vanadium catalysts, hydrogen, water and ammonia at 290.degree. C. with a 77% yield of caprolactam.
Furthermore, DE-A 43 19 134 describes the conversion of 6-aminocapronitrile into caprolactam in water in the liquid phase without the addition of a catalyst.
The abovementioned documents do not suggest a process by means of which caprolactam is obtained from adiponitrile via 6-aminocapronitrile in an overall process comprising both process steps.
It is an object of the present invention to provide a process for the simultaneous preparation of caprolactam and hexamethylenediamine starting from adiponitrile. Furthermore, it was intended to provide a process which gives pure 6-aminocapronitrile and hexamethylenediamine in a continuous process from the reaction mixture obtained in the partial hydrogenation of adiponitrile, the 6-aminocapronitrile being cyclized to caprolactam in a further process step. Moreover, byproducts obtained in this process were as far as possible to be reused, preferably recycled to an earlier process stage.
We have found that this object is achieved by a process for the simultaneous preparation of caprolactam and hexamethylenediamine starting from adiponitrile, wherein essentially 6-aminocapronitrile, hexamethylenediamine, ammonia, adiponitrile and hexamethyleneimine, and ammonia as the top product and a bottom product I, the distillation being carried out at a bottom temperature of from 60 to 250.degree. C. and a pressure of from 5 to 30 bar in the presence of a compound A which is inert under the distillation conditions, or a mixture of inert compounds A, which boils at from 60 to 250.degree. C. at 18 bar, and the ammonia not being completely separated off, and hexamethylenediamine, adiponitrile, hexamethyleneimine, inert compound or compounds A and ammonia, the ammonia content being lower than tha
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Achhammer Gunther
Bassler Peter
Fischer Rolf
Fuchs Eberhard
Hilprecht Lutz
BASF - Aktiengesellschaft
Keating Dominic
McKane Joseph K.
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