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US 4,727,163 AGranted
Process for preparing highly pure cyclic esters
AssigneeE. I. Du Pont de Nemours and Company
InventorHarold E. Bellis
Life of this patent
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Abstract
A process for making highly pure cyclic esters by heating a copolymer of .alpha.-hydroxy acid or its ester on a thermally stable polyether core.
Claims14
A process for making a cyclic ester of the formula ##STR3## wherein R.sup.1 and R.sup.2 can be independently hydrogen or an aliphatic hydrocarbon having from 1 to about 6 carbon atoms, the process comprising:
- a. forming a block copolymer of a thermally stable polyether core with a corresponding .alpha.-hydroxy acid or its ester on each end of the core, and then
- b. thermally degrading the ends at a suitable temperature and vacuum to evolve the cyclic ester and leave a thermally stable polyether residue.
Dependencies are inferred from the claim text.