Granted Patent B2

US 9,096,512 · App. 14/487,281 · Granted Aug 4, 2015

Abstract

Claims (19)

1. A method for preparing methacrylic acid, comprising the following steps:

a) oxidizing a compound of formula I

wherein R 1 is oxo or hydroxyl, to obtain isobutyric acid;

b) halogenating the isobutyric acid to obtain 3-haloisobutyric acid; and

c) dehalogenating the 3-haloisobutyric acid to obtain methacrylic acid wherein step b) is carried out in the presence of acetic anhydride.

2. The method of claim 1 , wherein R 1 is oxo.

3. The method of claim 1 , wherein R 1 is hydroxyl.

4. The method of claim 1 , wherein the compound of formula I is selected from isobutanol and isobutanal.

5. The method of claim 1 , wherein the oxidizing agent is selected from ozone, potassium permanganate, nitric acid, chromic acid and chromium trioxide.

6. The method of claim 5 , wherein the oxidizing agent is potassium permanganate.

7. The method of claim 1 , wherein the isobutyric acid is halogenated with a halogen selected from fluorine, chlorine, bromine, and iodine.

8. The method of claim 1 , wherein the isobutyric acid is halogenated with chlorine.

9. The method of claim 1 , further comprising the step of purifying the methacrylic acid.

10. The method of claim 9 , wherein the methacrylic acid is purified by distillation.

11. The method of claim 1 , wherein the compound of formula I is prepared by fermentation.

12. The method of claim 1 , wherein the 3-haloisobutryic acid is dehalogenated using an inorganic base.

13. The method of claim 12 , wherein the inorganic base is selected from sodium hydroxide and potassium hydroxide.

14. The method of claim 13 , wherein the inorganic base is sodium hydroxide.

15. The method of claim 1 , further comprising the step of esterifying the methacrylic acid to obtain a methacrylate ester.

Assignments (10)