Lactide production from dehydration of aqueous lactic acid feed
US5274127A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 18, 1990 |
| Grant date | Dec 28, 1993 |
| Priority date | — |
| Expiry date | Sep 18, 2010 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2367/04
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
The present invention is directed to a method for making L-lactide from aqueous L-lactic acid. Aqueous lactic acid feed for present purposes comprehends an aqueous mixture of one or more of L.sub.1 A, L.sub.2 A, and L.sub.3 A, optionally with LD being present. L-lactic acid is the preferred feed configuration for making L-lactide, and is to be understood even though the configuration symbol is not used throughout this application. Aqueous lactic acid feed is treated for removal of water therefrom until a degree of polymerization (DP) not substantially above about 2 is reached. The treatment then is ceased to produce a crude LD product. LD then is separated from the crude LD product. A preferred treatment involves heating the feed at elevated temperature to remove water. LD can be separated from the crude LD product by a variety of techniques to produce an LD-depleted product. This LD-depleted product, optionally augmented with additional aqueous lactic acid and/or water then can be readmitted to the process for making additional lactide. This cyclic or recycle process embodiment of the present invention enables very high lactide conversions to be realized.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.