Method for preparation of alkyl glycolates

• US 4,824,997 A
• Filed: 01/25/1988
• Issued: 04/25/1989
• Est. Priority Date: 01/25/1988
• Status: Expired due to Term

• Current Assignee: Astaris LLC (ICL Group Ltd.)
• Original Assignee: Monsanto Company (Bayer AG)
• Inventors: MacFarlane, Alistair, Dyroff, David R., Brill, Robert V.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/148,248
• Time in Patent Office: 456 Days
• Field of Search: 562/518, 560/179
• US Class Current: 560/179
• CPC Class Codes: C07C 69/675 of saturated hydroxy-carboxylic acids

Abstract

A method of carbonylation of formaldehyde is disclosed. In the method, an aqueous formaldehyde concentrate comprising between about 60% by weight and about 85% by weight formaldehyde, carbon monoxide and sulfuric acid are brought together in the absence of an effective amount of added Group IB cocatalyst in a reaction zone under a carbon monoxide partial pressure in the reaction zone of not greater than about 1.72×10⁷ N/M². A carbonylation reaction is thereby effected in which a carbonylation product is produced comprising at least about 2% by weight sulfuric acid and a mixture of compounds of the formula:

HO(CH.sub.2 COO).sub.n H

wherein n is a positive integer of at least 1. Also disclosed is a method for preparation of an alkyl glycolate by esterification of the carbonylation reaction mixture.

Claims

1. A method comprising:

bringing together in a reaction zone an aqueous formaldehyde concentrate comprising between about 60% by weight and about 85% by weight formaldehyde, carbon monoxide and a catalytic amount of sulfuric acid, in the absence of an effective amount of added Group IB cocatalyst, under a carbon monoxide partial pressure in said reaction zone of not greater than about 1.72×

10⁷ N/M² thereby effecting a carbonylation reaction in which a carboxylation product is produced comprising a mixture of compounds of the formula;

space="preserve" listing-type="equation">HO(CH.sub.2 COO).sub.n H

wherein n is an integer of at least 1 and in the range of from about 2% to about 10% by weight sulfuric acid.

2. A method as set forth in claim 1 wherein the formaldehyde conversion is at least about 90%.

3. A method as set forth in claim 2 wherein the selectivity to polyglycolide is at least about 85% based upon the formaldehyde converted.

4. A method as set forth in claim 1 wherein the concentration of formaldehyde in said aqueous formaldehyde concentrate is between about 70% by weight and about 80% by weight.

5. A method as set forth in claim 1 wherein the temperature in said reaction zone is between about 150°

C. and about 180°

C.

6. A method as set forth in claim 1 wherein the yield of polyglycolide is at least about 85 mole percent based on formaldehyde input.

7. A method as set forth in claim 1 wherein the reaction time is in the range of from about 2 to about 10 hours.

8. A method as set forth in claim 1 wherein the carbonylation reaction is a continuous process.

9. A method of claim 8 wherein the reaction time is within the range of from about 2 to about 20 hours.

10. A method of claim 1 wherein the pressure is in the range of from about 5.5×

10⁶ N/M² to about 1.38×

10⁷ N/M².

11. A method of claim 1 wherein the amount of sulfuric acid is an amount producing between about 2% to about 4%, by weight, in the reaction product.

12. A method for preparation of an alkyl glycolate by carbonylation of formaldehyde, the method comprising:

bringing together in a reaction zone an aqueous formaldehyde concentrate comprising between about 60% by weight and about 85% by weight formaldehyde, carbon monoxide and a catalytic amount of sulfuric acid, in the absence of an effective amount of added Group IB cocatalyst, the carbon monoxide partial pressure in said reaction zone being not greater than about 1.73×

10⁷ N/M², thereby effecting a reaction producing a carbonylation reaction mixture comprising in the range of from about 2% to about 10% by weight sulfuric acid and a mixture of polyglycolides having the formula;

space="preserve" listing-type="equation">HO(CH.sub.2 COO).sub.n H

wherein n is an integer of at least 1,

esterifying the polyglycolides contained in said carbonylation reaction, mixture without prior removal of the sulfuric acid, with an alcohol of the formula ROH to form an esterification product comprising an alkyl glycolate of the formula ##STR4## wherein R is lower alkyl.

13. A method as set forth in claim 12 wherein said carbonylation reaction mixture comprises between about 2% by weight and about 4% by weight sulfuric acid.

14. A method as set forth in claim 12 wherein the temperature in said reaction zone is between about 150°

C. and about 180°

C.

15. A method of claim 12 wherein the lower alkyl group is methyl.

16. A method as set forth in claim 12 further including the step of adding a base to said esterification product to produce a treated product comprising an alkyl glycolate and a precipitate.

17. A method as set forth in claim 16 wherein said precipitate is removed from said treated product by filtration, thereby producing a filtrate comprising said alkyl glycolate.

18. A method as set forth in claim 17, further comprising separating said alkyl glycolate from the filtrate.

19. A method as set forth in claim 18 wherein said alkyl glycolate is separated from the filtrate by distillation.

20. A method as set forth in claim 19 wherein said alkyl group is methyl.

21. A method as set forth in claim 12 wherein the formaldehyde conversion is at least about 90%.

22. A method as set forth in claim 21 wherein the selectivity to polyglycolide is at least about 85% based upon the formaldehyde converted.

23. A method as set forth in claim 12 wherein the concentration of formaldehyde in said aqueous formaldehyde concentrate is between about 70% by weight and about 80% by weight.

24. A method of claim 12 wherein the pressure is in the range of from about 5.5×

10⁶ N/M² to about 1.38×

10⁷ N/M².

25. A method as set forth in claim 12 wherein the yield of polyglycolide is at least about 85 mole percent based on formaldehyde input.

26. A method as set forth in claim 12 wherein the reaction time is in the range of from about 2 to about 10 hours.

27. A method as set forth in claim 12 wherein the carbonylation reaction is a continuous process.

28. A method of claim 27 wherein the reaction time is within the range of from about 2 to about 20 hours.