Process for the production of alkanolamide
The present invention relates to a process for the manufacture of alkanolamide containing compositions, and more particularly to a process of reacting a fatty acid and diethanolamine (DEA) which result in the formation of low levels of undesirable by products, particularly of bis-hydroxyethyl piperazine (BHEP).
1. A method of manufacture of a composition comprising an alkanolamide, the method comprising the steps of:
(a) adding diethanolamine (DEA) to a fatty acid at a low addition rate to form a mixture of fatty acid and DEA wherein the total molar quantity of fatty acid in the mixture is in excess of the total molar quantity of DEA;
(b) applying at least a partial vacuum to the mixture; and
(c) maintaining the mixture at a suitable temperature and for sufficient time for the reaction to proceed to form the alkanolamide.
2. The method of claim 1 wherein the fatty acid is selected from the group consisting of cocoate, capric, lauric, myristic, palmitic, stearic, oleic, linoleic, arachidonic, erucic and behenic acids and mixtures thereof.
3. The method of claim 1 wherein the fatty acid comprises isostearic acid.
4. The method of claim 1 wherein the fatty acid consists of isostearic acid.
5. The method of claim 1 wherein the DEA is added at a rate of from about 0.0001% to about 10% of total DEA per minute.
6. The method of claim 5 wherein the DEA is added at a rate of from about 0.001% to about 5% of total DEA per minute.
7. The method of claim 6 wherein the DEA is added at a rate of from about 0.001 to about 1% of total DEA per minute.
8. The method of claim 7 wherein the DEA is added at a rate of from about 0.002% to about 0.5% total DEA per minute.
9. The method of claim 1 wherein the total amount of fatty acid with respect to DEA is in the range of molar ratios of about 1:0.4-0.9 (fatty acid:DEA).
10. The method of claim 9 wherein the range of molar ratios is about 1:0.5-0.85.
11. The method of claim 10 wherein the range of molar ratios is about 1:0.6-0.8.
12. The method of claim 11 wherein the range of molar ratios is about 1:0.7.
13. The method of claim 1 wherein the mixture is maintained at a pressure of about 500 mm Hg or less for a substantial portion of the time of the reaction.
14. The method of claim 13 wherein the mixture is maintained at a pressure of about 250 mm Hg or less for a substantial portion of the time of the reaction.
15. The method of claim 14 wherein the mixture is maintained at a pressure of about 125 mm Hg or less for a substantial portion of the time of the reaction.
16. The method claim 15 wherein the mixture is maintained at a pressure of about 50 mm Hg or less for a substantial portion of the time of the reaction.
17. The method of claim 13 in which the pressure is maintained for essentially the entire time of the reaction.
18. The method of claim 17 in which the pressure is maintained for essentially the entire time of the reaction and the entire time of the addition of the DEA.
19. The method of claim 1 wherein the mixture is maintained at a temperature of from about 100° C. to about 170° C.
20. The method of claim 19 wherein the mixture is maintained at a temperature of from about 125° C. to about 160° C.
21. The method of claim 20 wherein the mixture is maintained at a temperature of from about 145° C. to about 155° C.
22. The method of claim 21 wherein the mixture is maintained at a temperature of from about 148° C. to about 152° C.