Method for esterification of carboxylic or polycarboxylic acid in the presence of supercritical fluids and catalysts therefor
US6204386A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 5, 1998 |
| Grant date | Mar 20, 2001 |
| Priority date | — |
| Expiry date | Nov 5, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P20/54
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
The esterification of a carboxylic or polycarboxylic acid, such as terephthalic acid, with ethylene oxide is conducted in the presence of a supercritical or near critical fluid with an esterification catalyst to form a monoester such as 2-hydroxyethylterephthalate (MHET). The monoester can be easily removed from the involatile terephthalic acid/catalyst bed by continuous extraction with supercritical fluid before subsequent reaction to the diester occurs. The esterification catalyst, such as quaternary ammonium salts, are at least substantially insoluble in the supercritical fluid and capable of withstanding prolonged exposure to elevated temperatures. The process is highly selective to formation of monoesters, and economical. The process can be modified for production of bis-esters or higher esters. The monoesters are polymerizable and can be used as monomers in the production of polyesters such as polyethylene terephthalate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.