Process for the preparation of 1,4-dioxane-2,5-diones

• US 5,326,887 A
• Filed: 02/14/1992
• Issued: 07/05/1994
• Est. Priority Date: 02/27/1991
• Status: Expired due to Fees

• Current Assignee: Ecological Chemical Products Company
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Nakamura, Charles E., Di Cosimo, Robert, Moran, John R.
• Primary Examiner(s): Ivy, C. Warren
• Assistant Examiner(s): COVINGTON, RAYMOND K
• Application Number:
  US07/836,228
• Time in Patent Office: 872 Days
• Field of Search: 549/357, 549/274
• US Class Current: 549/274
• CPC Class Codes: C07D 319/12 not condensed with other rings

Abstract

This invention relates to a process for preparing 1,4-dioxane-2,5-diones comprising reacting an α-hydroxy acid oligomer or an ester of an α-hydroxy acid oligomer over a fixed bed catalyst system.

Claims

1. 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 α

-hydroxy acid dimer substrate of structure;

##STR9## wherein each R is independently hydrogen on hydrocarbyl, optionally substituted with a halogen, and R⁶ is hydrocarbyl, optionally substituted with a halogen, and n=2, over a fixed bed catalyst, the process carried out at about 150°

C. to about 350°

C., wherein the reactants are in the vapor phase, followed by collection of the effluent product and wherein the equivalent alcohol of R⁶ has a pKa of less than 14.5.

2. The process of claim 1 wherein the equivalent alcohol of R⁶ is selected from a group consisting of 2-fluoroethanol, 2-chloroethanol, propargyl alcohol, 2,2,2-trifluoroethanol, 2,2,2-trichloroethanol and phenol.

3. The process of claim 1 wherein the substrate is first dissolved in an inert solvent, prior to heating.

4. The process of claim 3 wherein the solvent is capable of withstanding temperatures up to 350°

C. without solvent degradation.

5. The process of claim 4 wherein the solvent is selected from tetrahydrofuran and toluene.

6. The process of claim 1 wherein the catalyst is aluminum oxide.

7. The process of claim 6 wherein the catalyst additionally contains up to 18% silicon dioxide.

8. The process of claim 1 wherein the contact time between substrate and catalyst is 0.1 to 10 seconds.

9. The process of claim 8 wherein a stream of inert gas is added to the reaction mixture.

10. The process of claim 9 wherein the inert gas is selected from the group consisting of nitrogen, helium and argon.

11. The process of claim 10 wherein the inert gas is nitrogen.

13. The process of claim 1 wherein the catalyst is selected from zirconium oxide, titanium (IV) oxide, and molecular sieves type 3A and molecular sieves type 13X.

14. The process of claim 1 for making 1,4-dioxane 2,5-diones of the structure:

##STR12## wherein the substrate is a composition represented by the following Formula A;

##STR13## wherein;

R¹, R², R³, and R⁴ are each independently selected from H and hydrocarbyl and wherein R¹ and R² are not the same as R³ and R⁴ and wherein R⁶ is hydrocarbyl, optionally substituted with a halogen.

15. The process of claim 14 wherein R¹, R², R³, and R⁴ are selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, and aralkyl and R⁶ is selected from the group consisting of haloalkyl, and aryl.

12. A process for making optically active 1,4-dioxane-2,5-diones of the structure:

##STR10## where;

a) R⁷, R⁸, R⁹, and R¹⁰ 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 α

-hydroxy acid dimer substrate of structure;

##STR11## where R⁷, R⁸, R⁹, and R¹⁰ are defined above, R¹¹ 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°

C. to 250°

C., wherein the reactants are in the vapor phase and wherein the equivalent alcohol of R¹¹ has a pKa of less than 14.5.