Method for purifying lactams
US7384518B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 28, 2001 |
| Grant date | Jun 10, 2008 |
| Priority date | — |
| Expiry date | Jun 14, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S203/90
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A method and a plant are disclosed for purifying lactams, particularly lactams obtained by cyclizing hydrolysis of aminonitrile. The purification of ε-caprolactam obtained by cyclizing hydrolysis of aminocapronitrile is described which includes eliminating the ammonia from the reaction medium of the hydrolysis, then recovering the lactam from said medium in purified form. The recovery is carried out by performing at least a distillation of the lactam in the presence of a base producing optionally a fronts fraction comprising compounds more volatile than the lactam, a fraction comprising the lactam to be recovered to the degree of desired purity and a distillation tails comprising the lactam and compounds less volatile than the lactam. The distillation tails are treated by various processes such as evaporation in thin layers to recover the major part of the caprolactam and recycling the latter in the purification process. The method and plant enables a high rate of recovery of the caprolactam contained in the hydrolysis medium, while observing required criteria of purity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.