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A method for making an alkyl 3-hydroxybutyrate is provided. The method can include reacting an alkyl alcohol with diketene to form an alkyl acetoacetate and then hydrogenating the alkyl acetoacetate to form the alkyl 3-hydroxybutyrate. The method of the present invention may also include separating

A method for making an alkyl 3-hydroxybutyrate is provided. The method can include reacting an alkyl alcohol with diketene to form an alkyl acetoacetate and then hydrogenating the alkyl acetoacetate to form the alkyl 3-hydroxybutyrate. The method of the present invention may also include separating one or more impurities an alkyl acetoacetate stream and subjecting the purified acetoacetate mixture to hydrogenation to form the alkyl 3-hydroxybutyrate. Methods of the present invention can be carried out on a lab, pilot, or commercial scale.

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1. A method of making an alkyl 3-hydroxybutyrate, said method comprising: (a) reacting an alkyl alcohol with diketene to provide a first reaction mixture comprising an alkyl acetoacetate; and(b) hydrogenating at least a portion of said alkyl acetoacetate in said first reaction mixture to thereby pro

1. A method of making an alkyl 3-hydroxybutyrate, said method comprising: (a) reacting an alkyl alcohol with diketene to provide a first reaction mixture comprising an alkyl acetoacetate; and(b) hydrogenating at least a portion of said alkyl acetoacetate in said first reaction mixture to thereby provide a hydrogenated product stream comprising alkyl 3-hydroxybutyrate,wherein said alkyl group on the alkyl 3-hydroxybutyrate comprises an isopropyl group, n-propyl group, isobutyl group, n-butyl group, 2-butyl (sec-butyl) group, 2,2-dimethylethyl (tert-butyl) group, 3,3-dimethylpentyl (isopentyl) group, 1-pentyl (n-pentyl) group, 1-methylbutyl(2-pentyl) group, 2-methylbutyl group, 2-ethylpropyl(3-pentyl) group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl (neopentyl) group, or a cyclopentyl group,wherein said hydrogenating includes contacting at least a portion of said first reaction mixture with a hydrogen-containing gas and then heating the resulting mixture to a hydrogenation temperature in the range of from about 70° C. to about 90° C., in the presence of a hydrogenation catalyst. 2. The method of claim 1, wherein the alkyl group of said alkyl 3-hydroxybutyrate is an isopropyl group. 3. The method of claim 1, wherein the alkyl group of said alkyl 3-hydroxybutyrate is selected from the group consisting of isobutyl, n-butyl, and 2-butyl. 4. The method of claim 1, wherein at least a portion of said reacting is carried out in the presence of a catalyst. 5. The method of claim 4, wherein said catalyst has a vapor pressure in the range of from about 45 torr to about 75 torr measured at 25° C. 6. The method of claim 4, wherein said catalyst is present in an amount in the range of from about 0.1 to about 10 weight percent, based on the total weight of said reaction mixture. 7. The method of claim 4, wherein said catalyst comprises a trialkylamine. 8. The method of claim 1, wherein said alkyl alcohol is reacted with said diketene at a temperature in the range of from about 55 to about 105° C. 9. The method of claim 1, wherein said alkyl alcohol is reacted with said diketene at a pressure within a range of 13 to 25 psia. 10. The method of claim 1, further comprising, prior to said reacting, combining a catalyst with said alkyl alcohol to form a precursor reaction mixture and adding said diketene to said precursor reaction mixture to initiate said reacting, wherein during the addition of said diketene to said precursor reaction mixture, the average temperature of said precursor reaction mixture is maintained at a target temperature in the range of from about 65 to about 105° C. 11. The method of claim 1, further comprising prior to said hydrogenating, separating at least one impurity from said first reaction mixture to provide a purified reaction mixture and hydrogenating at least a portion of said purified reaction mixture. 12. The method of claim 11, wherein at least a portion of said separating is carried out at a pressure not more than 760 torr. 13. The method of claim 12, wherein at least a portion of said separating is carried out at a temperature in the range of from about 15 to about 70° C. and a pressure in the range of from about 1 to about 30 torr. 14. The method of claim 13, wherein another portion of said separating is carried out at a temperature in the range of from about 70 to about 90° C. and a pressure in the range of from about 1 to about 15 torr. 15. The method of claim 11, wherein said impurity comprises a component selected from the group consisting of acetic acid, acetone, alkyl acetate, and combinations thereof. 16. The method of claim 11, wherein said impurity comprises a component selected from the group consisting of dimers of acetoacetate, alkyl butyrate, and combinations thereof. 17. The method of claim 1, wherein the first reaction mixture is contacted with a hydrogen-containing gas at a pressure in the range of from about 300 psig to about 1200 psig. 18. The method of claim 1, wherein the first reaction mixture has a pH in the range of from about 4 to about 8 upon contact with the hydrogen containing gas. 19. The method of claim 1, wherein said hydrogenation catalyst comprises at least one catalytic metal selected from the group consisting of platinum, palladium, ruthenium, nickel, and combinations thereof. 20. The method of claim 19, wherein said hydrogenation catalyst is a heterogeneous catalyst, wherein said catalytic metal is supported on, in, and/or within a support, and wherein said support is not acidic. 21. The method of claim 19, wherein said catalytic metal is selected from the group consisting of ruthenium, nickel, and combinations thereof. 22. The method of claim 20, wherein said catalytic metal is present in said catalyst in an amount in the range of from about 1 to about 6 weight percent, based on the total weight of said catalyst. 23. The method of claim 22, wherein said catalytic metal is ruthenium. 24. The method of claim 1, wherein said alkyl 3-hydroxybutyrate has a vapor pressure in the range of from about 0.055 to about 0.10 torr measured at 20° C. 25. The method of claim 1, wherein said alkyl 3-hydroxybutyrate has a corn oil-water coupling efficiency measured at 23° C. in the range of from 5 grams/gram to 12 grams/gram. 26. The method of claim 1, wherein at least a portion of said reacting and at least a portion of said hydrogenating are carried out in different vessels. 27. The method of claim 1, wherein at least one of said reacting and said hydrogenating are carried out continuously. 28. A method for producing an alkyl 3-hydroxybutyrate, said method comprising: (a) separating a feed stream comprising at least one alkyl acetoacetate in a first distillation column into an impurities-enriched overhead vapor stream and an impurities-depleted liquid bottoms stream,(b) separating said impurities-depleted liquid bottoms stream into an alkyl acetoacetate-enriched overhead vapor stream and an alkyl acetoacetate-depleted liquid bottoms stream; and(b) hydrogenating at least a portion of the alkyl acetoacetate in said alkyl acetoacetate-enriched overhead vapor stream to thereby provide a hydrogenated product stream comprising an alkyl 3-hydroxybutyrate,wherein said alkyl group on the alkyl 3-hydroxybutyrate comprises an isopropyl group, n-propyl group, isobutyl group, n-butyl group, 2-butyl (sec-butyl) group, 2,2-dimethylethyl (tert-butyl) group, 3,3-dimethylpentyl (isopentyl) group, 1-pentyl (n-pentyl) group, 1-methylbutyl(2-pentyl) group, 2-methylbutyl group, 2-ethylpropyl(3-pentyl) group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl (neopentyl) group, or a cyclopentyl group,wherein said hydrogenating includes contacting at least a portion of said alkyl acetoacetate-enriched overhead vapor stream with a hydrogen-containing gas and then heating the resulting mixture to a hydrogenation temperature of greater than 65° C. in the presence of a hydrogenation catalyst. 29. The method of claim 28, wherein the alkyl group of said alkyl 3-hydroxybutyrate is an isopropyl group. 30. The method of claim 28, wherein the alkyl group of said alkyl 3-hydroxybutyrate is selected from the group consisting of isopropyl, isobutyl, n-butyl, and 2-butyl. 31. The method of claim 28, wherein said alkyl group of said alkyl 3-hydroxybutyrate is n-butyl. 32. The method of claim 28, wherein said impurities-depleted liquid bottoms stream comprises at least 50 percent of the total amount of alkyl acetoacetate present in said feed stream. 33. The method of claim 28, wherein the first distillation column is operated at a temperature in the range of from about 15 to about 70° C. and a pressure in the range of from about 1 to about 30 torr, wherein the molar ratio of the amount of acetoacetate in said impurities-enriched overhead vapor stream to the amount of acetoacetate in said impurities-depleted liquid bottoms stream is in the range of from about 0.01:1 to about 0.25:1. 34. The method of claim 28, wherein said impurities-depleted liquid bottoms stream comprises at least about 75 percent of the total amount of alkyl acetoacetate present in said feed stream introduced into said first distillation column. 35. The method of claim 28, wherein said impurities-enriched overhead vapor stream comprises one or more impurities selected from the group consisting of acetic acid, acetone, an alkyl alcohol, an alkyl acetate, and combinations thereof. 36. The method of claim 28, further comprising, separating at least a portion of said impurities-depleted liquid bottoms stream into an alkyl acetoacetate-enriched overhead vapor stream and an alkyl acetoacetate-depleted liquid bottoms stream in a second distillation column, wherein said impurities-depleted stream contacted with said hydrogen-containing gas comprises said second overhead stream. 37. The method of claim 36, wherein said alkyl acetoacetate-enriched overhead vapor stream has a total impurities content of not more than 1 weight percent, based on the total weight of said alkyl acetoacetate-enriched overhead vapor stream. 38. The method of claim 36, wherein at least one of said first and said second distillation columns are operated at a pressure of not more than 30 torr. 39. The method of claim 28, wherein said alkyl 3-hydroxybutyrate has a boiling point in the range of from about 210° C. to about 230° C. 40. The method of claim 28, wherein said alkyl 3-hydroxybutyrate has a vapor pressure in the range of from about 0.055 torr to about 0.10 torr measured at 20° C. 41. The method of claim 28, wherein said alkyl 3-hydroxybutyrate has a solubility in deionized water at 23° C. in the range of from about 2 to about 20 percent. 42. The method of claim 28, wherein said alkyl 3-hydroxybutyrate has a corn oil-water coupling efficiency in the range of from about 5 grams/gram to about 15 grams/gram. 43. The method of claim 28, further comprising, prior to said separating, reacting an alkyl alcohol with diketene to form a first reaction mixture comprising said alkyl acetoacetate, wherein said feed stream comprises said first reaction mixture. 44. The method of claim 1, wherein said hydrogenation temperature is in the range of from 80° C. to 90° C. 45. The method of claim 28, wherein said hydrogenation temperature is in the range of from 80° C. to 100° C. 46. The method of claim 28, wherein said hydrogenation temperature is in the range of from 70° C. to 90° C. 47. The method of claim 28, wherein said hydrogenation catalyst comprises at least one catalytic metal selected from the group consisting of ruthenium, nickel, and combinations thereof. 48. The method of claim 47, wherein said hydrogenation catalyst further comprises at least one support, wherein said support comprises carbon.