Preparation of diesters of (meth)acrylic acid from epoxides

1. A process for preparation of a diester of general Formula (I):

wherein:

R 1 is a hydrogen atom or a methyl group;

R 2 to R 6 are independently selected from hydrogen atoms or optionally substituted aliphatic or aromatic substituents having up to 17 carbon atoms;

wherein the process comprises at least process step (a):

(a) reacting a (meth)acrylic anhydride of general Formula (II):

with an epoxide of general Formula (III):

to deliver a product mixture comprising the diester of general Formula (I);

wherein the reaction is carried out in the presence of a catalyst in combination with a co-catalyst, wherein:

the catalyst comprises a first catalyst, a second catalyst or a combination of both, and:

the first catalyst is a halide of magnesium or a trifluoromethanesulfonate of a rare earth element; and

the second catalyst is a chromium (III) salt;

the co-catalyst is selected from the group consisting of: a tertiary amine; a quaternary ammonium salt; a tertiary phosphine; and a quaternary phosphonium salt.

2. The process of claim 1 , wherein:

R 1 is a hydrogen atom, R 2 is a vinyl group, and the (meth)acrylic anhydride of formula (II) is acrylic acid anhydride; or alternatively:

R 1 is a methyl group, R 2 is a 1-methylvinyl group and the (meth)acrylic anhydride of formula (II) is methacrylic acid anhydride.

3. The process of claim 1 , wherein the optionally substituted aliphatic or aromatic substituents having up to 17 carbon atoms are selected from the group consisting of:

optionally substituted alkyl, cycloalkyl, alkenyl, or alkadienyl substituents having up to 17 carbon atoms optionally substituted with one substituent R 7 selected from: a halogen atom, —CN, —SCN, —OCN, and —NCO.

4. The process of claim 1 , wherein the epoxide of general Formula (III) is selected from the group consisting of: ethylene oxide; propylene oxide; 1-hexene oxide; cyclohexene oxide; cyclopentene oxide; 1-butene oxide; 2-butene oxide; isobutene oxide; styrene oxide; and glycidyl methacrylate.

5. The process of claim 1 , wherein process step (a) is carried out in the presence of the first catalyst, the second catalyst and the co-catalyst.

6. The process of claim 1 , wherein the co-catalyst is a quaternary ammonium salt.

7. The process of claim 1 , wherein the co-catalyst is selected from the group consisting of: tetrabutylammonium chloride; tetrabutylammonium bromide;

tetraethylammonium chloride; tetrabutylammonium acetate; tetramethylammonium chloride; tetrapentylammonium bromide; cetyl-trimethylammonium bromide; 1-butyl-3-methyl-imidazolyl chloride; cetylpyridinium chloride; and triethylbenzylammonium chloride.

8. The process of claim 1 , wherein the second catalyst is a chromium (III) carboxylate.

9. The process of claim 8 , wherein the chromium (III) carboxylate is selected from the group consisting of: chromium (III) 2-ethylhexanoate; chromium (III) heptanoate; chromium (III) acetate; and chromium (III) methacrylate.

10. The process of claim 1 , wherein the total amount of the first catalyst in process step (a) is between 0.001 mol.-% and 10 mol.-%, based on the amount of the epoxide of general Formula (III).

11. The process of claim 1 , wherein the total amount of the second catalyst in process step (a) is between 0.001 mol.-% and 10 mol.-%, based on the amount of the epoxide of general Formula (III).

12. The process of claim 1 , wherein the total amount of the co-catalyst in process step (a) is between 0.001 mol.-% and 10 mol.-%, based on the amount of the epoxide of general Formula (III).

13. The process of claim 1 , wherein the molar ratio anhydride of the general Formula (II): epoxide of the general Formula (III) in process step (a) is between 5:1 and 1:0.1.

14. The process of claim 1 , wherein the temperature during process step (a) is in the range 20° C. to 140° C.

15. The process of claim 1 , wherein the process is carried out in the presence of at least 10 mol % excess of the anhydride.

16. The process of claim 15 , further comprising process steps (b) and (c) which are carried out after process step (a):

(b) adding an auxiliary alcohol to the product mixture obtained in process step (a) to form a product mixture comprising the diester of the general Formula (I) and an ester of the auxiliary alcohol; and

(c) removing of the ester of the auxiliary alcohol from the product mixture obtained in process step (b);

wherein the auxiliary alcohol is a primary or secondary alcohol having a boiling point of not more than 150° C., measured at a pressure of 10 5 Pa.

17. The process of claim 16 , wherein, in process step (c), the ester of the auxiliary alcohol is removed from the product mixture by distillation.

18. The process of claim 17 , wherein, in process step (a) the epoxide of general Formula (III) is selected from the group consisting of: ethylene oxide; propylene oxide; 1-hexene oxide; cyclohexene oxide; cyclopentene oxide; 1-butene oxide; 2-butene oxide; isobutene oxide; styrene oxide; and glycidyl methacrylate.

19. The process of claim 18 , wherein process step (a) is carried out in the presence of the first catalyst, the second catalyst and the co-catalyst.

20. The process of claim 19 , wherein the co-catalyst is selected from the group consisting of: tetrabutylammonium chloride; tetrabutylammonium bromide;

tetraethylammonium chloride; tetrabutylammonium acetate; tetramethylammonium chloride; tetrapentylammonium bromide; cetyl-trimethylammonium bromide; 1-butyl-3-methyl-imidazolyl chloride; cetylpyridinium chloride; and triethylbenzylammonium chloride; and the second catalyst is a chromium (III) carboxylate.