Separation of 6-aminocapronitrile and hexamethylenediamine from a mixture comprising hexamethylenediamine, 6-aminocapronitrile and tetrahydroazepine
US7208632B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 10, 2004 |
| Grant date | Apr 24, 2007 |
| Priority date | — |
| Expiry date | Apr 14, 2025 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C253/34
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
The invention relates to the field of separation by distillation of 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) from a mixture comprising ACN, HMD, tetrahydroazepine (THA), adiponitrile (ADN) and low boilers (LB). Also disclosed is a method for producing a distillate stream comprising HMD; a side draw stream comprising ACN, THA and low levels of dimers of ACN and HMD; and a tails stream comprising ACN, THA and substantially higher levels of dimers of ACN and HMD than found in the side draw stream. The side draw stream is particularly suitable for use in the production of caprolactam since the low levels of dimers of ACN and HMD do not greatly affect the catalyst life in the caprolactam production process. The tails stream can be further distilled to produce a tails distillate stream comprising ACN and THA, which can be recycled back to the first distillation column, further increasing recovery of ACN from the feed stream. Process conditions of the method of the invention disfavor the production of 2-cyanocyclopentylideneimine (CPI).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.