Process for preparing dithioesters

1. A process for preparing a dithioester, comprising:

reacting a) a benzenedithiocarboxylic acid or b) a benzenedithiocarboxylic salt or c) a mixture of a) and b) represented by formula (I)

wherein R 1 is a group having from 1 to 20 carbon atoms, m is an integer from 1 to 6, and M is a hydrogen atom, an alkali metal ion, an ammonium ion or a group having an alkaline earth metal ion with a (i) vinyl compound of formula (II)

wherein R 2 , R 3 , R 4 and R 5 are each independently hydrogen or a radical having from 1 to 20 carbon atoms or (ii) an alkyl compound which has a leaving group and is represented by formula (III)

wherein R 6 R 7 and R 8 are each independently hydrogen or a radical having from 1 to 20 carbon atoms, and X is a leaving group or iii) a mixture of i) and ii) in a biphasic system;

wherein one phase of said biphasic system comprises water,

wherein the other phase of said biphasic system is an organic phase; and

wherein a weight ratio of said phase comprising water to said organic phase is from 95:5 to 5:95.

2. The process as claimed in claim 1 , wherein said organic phase comprises an inert organic solvent.

3. The process as claimed in claim 2 , wherein said inert organic solvent is an aliphatic hydrocarbon.

4. The process as claimed in claim 3 , wherein said aliphatic hydrocarbon is selected from the group consisting of hexane, heptane, octane and nonane.

5. The process as claimed in claim 2 , wherein said inert organic solvent is a mineral oil.

6. The process as claimed in claim 1 , wherein said dithiocarboxylic salt is dissolved in said phase comprising water.

7. The process as claimed in claim 1 , wherein the pH of said phase comprising water is less than or equal to 6.

8. The process as claimed in claim 7 , wherein said phase comprising water is admixed with a strong acid.

9. The process as claimed in claim 8 , wherein the acid is selected from the group consisting of HCl, HBr, HI; H 2 SO 4 , methanesulfonic acid, p-toluenesulfonic acid, nitric acid and trifluoroacetic acid.

10. The process as claimed in claim 1 , wherein a haloalkyl compound or a vinyl compound or a mixture of a haloalkyl compound and a vinyl compound is dissolved in said organic phase.

11. The process as claimed in claim 1 , wherein a) said dithiocarboxylic acid or b) said dithiocarboxylic salt or c) said a mixture of a) and b) has at least one free-radical-stabilizing substituent.

12. The process as claimed in claim 11 , wherein said free-radical-stabilizing substituent is selected from the group consisting of —CN, —COR and —CO 2 R,

wherein R is an alkyl radical, an aryl radical, an aromatic group or a heteroaromatic group.

13. The process as claimed in claim 1 , wherein said reaction proceeds in the presence of a phase transfer catalyst.

14. The process as claimed in claim 1 , wherein the weight ratio of said phase comprising water to organic phase ranges from 80:20 to 20:80.

15. The process as claimed in claim 1 , wherein said reacting is carried out at a temperature of from −10 to 1000° C.

16. The process as claimed in claim 1 , wherein said reaction is conducted under a protective gas atmosphere.

17. The process as claimed in claim 1 , wherein said alkyl compound which has a leaving group an alkyl halide, an alkyl compound having a pseudohalide group or an alkyl compound having a sulfonate group.

18. The process as claimed in claim 1 , wherein said dithiocarboxylic acid or said dithiocarboxylic salt is represented by formula (I)

wherein

R 1 is a group having from 1 to 20 carbon atoms,

m is an integer from 1 to 6, and

M is a hydrogen atom, an alkali metal ion, an ammonium ion or a group having an alkaline earth metal ion.

19. The process as claimed in claim 1 , wherein said dithiocarboxylic acid or said dithiocarboxylic salt is reacted with a vinyl compound of formula (II)

wherein R 2 , R 3 , R 4 and R 5 are each independently hydrogen or a radical having from 1 to 20 carbon atoms.

20. The process as claimed in claim 19 , wherein at least one of R 2 , R 3 , R 4 and R 5 is an aromatic group.

21. The process as claimed in claim 1 , wherein said dithiocarboxylic acid or said dithiocarboxylic salt is reacted with a compound which has a leaving group and is represented by formula (III)

wherein

R 6 R 7 and R 8 are each independently hydrogen or a radical having from 1 to 20 carbon atoms, and

X is a leaving group.

22. A process for preparing cumyl dithiobenzoate, comprising:

reacting a) a benzenedithiocarboxylic acid or b) a benzenedithiocarboxylic salt or c) a mixture of a) and b) with i) α-methylstyrene or ii) a cumyl compound which has a leaving group or iii) a mixture of i) and ii) in a biphasic system;

wherein one phase of said biphasic system comprises water;

wherein the other phase of said biphasic system is an organic phase; and

wherein a weight ratio of said phase comprising water to said organic phase is from 95:5 to 5:95.