Back to results
US 5,326,887 AGranted
Process for the preparation of 1,4-dioxane-2,5-diones
AssigneeE. I. Du Pont de Nemours and Company
InventorsRobert Di Cosimo, John R. Moran, Charles E. Nakamura
Life of this patent
Estimating the term…
Abstract
This invention relates to a process for preparing 1,4-dioxane-2,5-diones comprising reacting an .alpha.-hydroxy acid oligomer or an ester of an .alpha.-hydroxy acid oligomer over a fixed bed catalyst system.
Claims15
A process for making 1,4-dioxane-2,5-diones of the structure:
- ##STR8## wherein each R is independently H or hydrocarbyl, optionally substituted with a halogen, by reacting an ester of an .alpha.-hydroxy acid dimer substrate of structure:
- ##STR9## wherein each R is independently hydrogen on hydrocarbyl, optionally substituted with a halogen, and R.sup.6 is hydrocarbyl, optionally substituted with a halogen, and n=2, over a fixed bed catalyst, the process carried out at about 150.degree. C. to about 350.degree. C., wherein the reactants are in the vapor phase, followed by collection of the effluent product and wherein the equivalent alcohol of R.sup.6 has a pKa of less than 14.5.
A process for making optically active 1,4-dioxane-2,5-diones of the structure:
- ##STR10## where:
- a) R.sup.7, R.sup.8, R.sup.9, and R.sup.10 are independently H, unsubstituted straight chain alkyl, or unsubstituted branched chain alkyl;
- and
- b) the structure contains at least one chiral center, by reacting an ester of an .alpha.-hydroxy acid dimer substrate of structure:
- ##STR11## where R.sup.7, R.sup.8, R.sup.9, and R.sup.10 are defined above, R.sup.11 is hydrocarbyl, optionally substituted with a halogen, and the structure contains at least one chiral center, the reaction carried out over a fixed bed catalyst, at about 150.degree. C. to 250.degree. C., wherein the reactants are in the vapor phase and wherein the equivalent alcohol of R.sup.11 has a pKa of less than 14.5.
2 more elements
Dependencies are inferred from the claim text.