Catalytic production of lactide directly from lactic acid
US5332839A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 18, 1990 |
| Grant date | Jul 26, 1994 |
| Priority date | — |
| Expiry date | Sep 18, 2010 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01J2219/1942
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
The present invention is directed to a method for making lactide from aqueous lactic acid. The invention method comprises converting feed aqueous lactic acid to its vapor phase. The feed vapors then are passed through a reactor maintained at elevated temperature and in which optionally is disposed an alumina catalyst. Withdrawn from the reactor is product lactide, water, and unreacted lactic acid which are subjected to separation for recovery of the lactide product. The separated unreacted lactic acid is eligible for readmission to the process for making additional lactide. This cyclic process embodiment of the present invention comprises the steps of passing make-up aqueous lactic acid feed into a vaporization zone along with unreacted aqueous lactic acid filtrate from another step of the process and therein forming aqueous lactic acid feed vapors. The thus-generated vapors that are passed through a vapor phase reaction zone held at elevated temperature for forming lactide therein. Lactide as a solid is separated from unreacted aqueous lactic acid filtrate; and the filtrate is passed into the vaporization zone in the initial step of the process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.