Methods for producing an ester of an alpha, beta-unsaturated carboxylic acid

1. A method for producing an ester of an alpha,beta-unsaturated carboxylic acid, comprising:

a) obtaining a four-carbon beta-hydroxycarboxylic acid recovery bottom derived from beta-hydroxy carboxylic acid distillate recovery bottom streams;

b) mixing a mono-alcohol with the four-carbon beta-hydroxycarboxylic acid recovery bottom to obtain a first mixture;

c) heating the first mixture to form a reaction product; and

d) distilling the reaction product and recovering a fraction comprising an ester of a four-carbon alpha,beta-unsaturated carboxylic acid.

2. The method of claim 1 , wherein the beta-hydroxycarboxylic acid recovery bottom comprises:

i) at least 40 percent by weight four-carbon beta-hydroxyalkanoate equivalents;

ii) from 0.1 percent by weight to 50 percent by weight free four-carbon beta-hydroxyalkanoates;

iii) at least 1 percent by weight saccharide equivalents; and

iv) less than 5 percent by weight water.

3. The method of claim 1 , wherein the fraction of step d) comprises:

i) at least 80 percent by weight of the ester of the four-carbon alpha,beta-unsaturated carboxylic acid;

ii) less than 1 percent by weight four-carbon beta-hydroxycarboxylic acid;

iii) less than 1 percent by weight water; and

iv) less than 0.5 percent by weight saccharide equivalents.

4. The method of claim 1 , wherein the beta-hydroxycarboxylic acid recovery bottom comprises 3-hydroxybutyric acid, 3-hydroxyisobutyric acid, 3-hydroxybutyrate, or 3-hydroxyisobutyrate.

5. The method of claim 1 , wherein the ester of the four-carbon alpha,beta-unsaturated carboxylic acid ester comprises alkyl methacrylate, alkyl 2-butenoate or mixtures thereof.

6. The method of claim 1 , wherein step (d) comprises dehydrating a four-carbon beta-hydroxyalkanoate to form an ester of a four-carbon alpha,beta-unsaturated carboxylic acid.

7. The method of claim 1 , wherein step (c) is carried out in the presence of a catalyst.

8. The method of claim 7 , wherein the catalyst is a solid acid catalyst, a Bronsted acid, or a Lewis acid.

9. The method of claim 7 , wherein the catalyst is sulfuric acid, and the initial amount of catalyst present is from 0.01 to 5 percent by weight of the four-carbon beta-hydroxyalkanoate containing composition.

10. The method of claim 7 , wherein the catalyst is sulfuric acid, and the initial amount of catalyst present is from 0.5 to 2 percent by weight of the four-carbon beta-hydroxyalkanoate containing composition.

11. The method of claim 1 , wherein an acrylate anti-polymerization agent is added prior to or during the method.

12. The method of claim 11 , wherein the acrylate anti-polymerization agent is added prior to or during step (d).

13. The method of claim 11 , wherein the acrylate anti-polymerization agent is added prior to or during step (c).

14. The method of claim 13 , wherein the anti-polymerization agent is present at from 10 ppm to 10,000 ppm.

15. The method of claim 6 , wherein prior to the dehydrating of step (d), the water content is less than 2 wt %.

16. The method of claim 1 , wherein the temperature during the dehydrating of step (d) is at least 120° C.

17. The method of claim 6 , wherein after step (c) and prior to the dehydrating of step (d) mono-alcohol and water are removed.

18. The method of claim 6 , wherein the temperature during step (c) is less than 130° C.

19. The method of claim 1 , wherein the fraction of step (d) comprises at least 50 percent by weight ester of the four-carbon alpha,beta-unsaturated carboxylic acid.