Process for the preparation of glyoxylic hemiacetal esters

• US 4,692,547 A
• Filed: 12/18/1985
• Issued: 09/08/1987
• Est. Priority Date: 12/20/1984
• Status: Expired due to Fees

• Current Assignee: Hoechst Aktiengesellschaft (Sanofi )
• Original Assignee: Hoechst Aktiengesellschaft (Sanofi )
• Inventors: Leupold, Ernst I., Driscoll, Robert K., Ebertz, Wolfgang
• Primary Examiner(s): Lone, Werren B.
• Assistant Examiner(s): CLARKE, VERA
• Application Number:
  US06/810,519
• Time in Patent Office: 629 Days
• Field of Search: 560/179, 560/186
• US Class Current: 560/186
• CPC Class Codes: C07C 69/67 of saturated acids
• CPC Class Codes: C07C 69/708 Ethers

Abstract

The invention relates to a process for the preparation of glyoxylic hemiacetal esters, in which first glycolic esters are oxydehydrogenated to give glyoxylic esters, and then the latter are reacted with an alcohol. The gaseous reaction mixture formed in the oxydehydrogenation is introduced, together with an excess of an alcohol which is suitable as an entraining agent, into a distillation column and then the water of reaction is distilled overhead together with other low-boilers and part of the excess alcohol, the glyoxylic hemiacetal ester and the remainder of the excess alcohol resulting as the bottom product.

In a variant of the process, use is made of an additional inert entraining agent whose azeotrope with water boils below 90° C. and below the alcohol which is used, and then the water of reaction is distilled overhead with the assistance of this entraining agent.

Claims

1. A process for the preparation of a glyoxylic hemiacetal ester, which comprises catalytically oxydehydrogenating a glycolic ester in a gas phase at a temperature between 100°

and 600°

C. and a residence time between 0.05 and 1 second to give a gaseous reaction mixture containing a glyoxylic ester, introducing the gaseous reaction mixture with 1 to 30 mole of a saturated primary or secondary alcohol per mole of the glyoxylic ester into a distillation column, said alcohol having 2 to 8 carbon atoms and being suitable as an entraining agent, and then reacting the glyoxylic ester with the alcohol and distilling overhead the water of reaction, other low boilers and part of the excess alcohol to yield a glyoxylic hemiacetal ester and the remainder of the excess alcohol as the bottom product.

2. The process as claimed in claim 1, wherein the catalyst for the oxydehydrogenation contains at least one element selected from the group consisting of Ag, V, Mo, Cu, Au, Sn, Sb, Bi and P on a support.

3. The process as claimed in claim 1, wherein 2 to 20 mole of the alcohol per mole of the glyoxylic ester is introduced into the distillation column.

4. A process for the preparation of a glyoxylic hemiacetal ester, which comprises catalytically oxydehydrogenating a glycolic ester in a gas phase at a temperature between 100°

and 600°

C. and a residence time between 0.05 and 1 second to give a gaseous reaction mixture containing a glyoxylic ester, introducing the gaseous reaction mixture with an inert entraining agent and 1 to 30 mole of a saturated primary or secondary alcohol per mole of the glyoxylic ester into a distillation column, said alcohol having 1 to 8 carbon atoms and said inert entraining agent forming an azeotrope with water which boils below 90°

C. and below the alcohol, and then reacting the glyoxylic ester with the alcohol and distilling overhead the water of reaction, other low boilers and the entraining agent to yield a glyoxylic hemiacetal ester and the excess alcohol as the bottom product.

5. The process as claimed in claim 4, wherein the catalyst for the oxydehydrogenation contains at least one element selected from the group consisting of Ag, V, Mo, Cu, Au, Sn, Sb, Bi and P on a support.

6. The process as claimed in claim 4, wherein the inert entraining agent is selected from the group consisting of CH₂ Cl₂, CHCl₃, CCl₄, n-pentane, n-hexane, cyclohexane and benzene.

7. The process as claimed in claim 4, wherein 2 to 10 mole of the alcohol per mole of the glyoxylic ester is introduced into the distillation column.

8. The process as claimed in claim 4, wherein the inert entraining agent forms an azeotrope with water which boils below 80°

C. and below the alcohol.