Process for producing a conjugated di- or poly-unsaturated fatty acid of 12 to 24 carbon atoms or salt or ester thereof

1. A process for producing a conjugated di- or poly-unsaturated fatty acid having from 12 to 24 carbon atoms, or a salt or ester thereof, which comprise reacting a non-conjugated free fatty acid, or a salt or ester thereof, with a base in the presence of a solvent comprising a monohydric alcohol having from 1 to 6 carbon atoms, wherein the reaction is carried out at a temperature of from 120° C. to 200° C. in the presence of water in an amount of at least 4% by weight based on alcohol.

2. Process as claimed in claim 1 , wherein the alcohol is selected from the group consisting of ethanol, methanol and mixtures thereof.

3. Process as claimed in claim 1 , wherein the base is an alkali metal hydroxide selected from the group consisting of potassium hydroxide, sodium hydroxide and mixtures thereof.

4. Process as claimed in claim 1 , wherein the amount of water is from 5% to 35% by weight based on alcohol.

5. Process as claimed in claim 1 , wherein the amount of water is from 10% to 30% by weight based on alcohol.

6. Process as claimed in claim 1 , wherein the conjugated fatty acid contains less than 5% by weight of trans, trans isomers.

7. Process as claimed in claim 6 , wherein the reaction is carried out at a temperature of from 140° C. to 180° C.

8. Process as claimed in claim 1 , wherein the molar ratio of base to non-conjugated free fatty acid, or salt or ester thereof, is from 1.07 to 3.5.

9. Process as claimed in claim 1 , wherein the non-conjugated free fatty acid, or salt or ester thereof, is selected from the group consisting of vegetable oils, free acids derived from these oils and C 1 to C 6 alkyl esters of these free acids.

10. Process as claimed in claim 9 , wherein the vegetable oil is selected from the group consisting of sunflower oil, rape seed oil, soy bean oil, safflower oil, linseed oil and mixtures thereof.

11. Process as claimed in claim 1 , wherein the non-conjugated fatty acid and the conjugated fatty acid are C18:2 fatty acids.

12. Process as claimed in claim 11 , wherein the process is carried out for a time and at a temperature to form a product comprising more than 70% by weight based on total fatty acid and salt and ester thereof, of cis-9, trans-11 and trans-10, cis-12 isomers of the conjugated fatty acid.

13. Process as claimed in claim 11 or claim 12 , wherein the process is carried out for a time and at a temperature to form a product comprising less than 3% by weight of linoleic acid and salts and esters thereof, based on total fatty acid and salt thereof.

14. Process as claimed in claim 1 , which further comprises separating conjugated fatty acid from the reaction mixture by a method comprising treatment with an acid and separation of the aqueous phase from the organic phase.

15. Process as claimed in claim 1 which further comprises the step of purifying the conjugated fatty acid.

16. Process as claimed in claim 1 which further comprises the step of forming a mono-, di-, or tri-glyceride of the conjugated fatty acid.

17. Process as claimed in claim 6 wherein the conjugated fatty acid contains less than 1% by weight of trans, trans isomers.

18. Process as claimed in claim 8 wherein the molar ratio of base to non-conjugated fatty acid, or salt or ester thereof, is from 1:3 to 1:6.

19. Process as claimed in claim 12 wherein the process is carried out for a time and at a temperature to form a product comprising more than 80% by weight based on total fatty acid and salt and ester thereof, of cis-9, trans-11 and trans-10, cis-12 isomers of the conjugated fatty acid.