Method for synthesizing a salt of a monoester of citric acid

Claim 1

A process for synthesizing a monoester of citric acid comprising: (a) mixing citric acid and an organic anhydride to form a reaction mixture, the organic anhydride having the formula ##STR5## where R 4 and R 5 are independently selected from the group consisting of hydrocarbon chains having from 1 to 5 carbon atoms or, with R 4 and R 5 taken together, having 6 to 8 carbon atoms linked to form a cycloaliphatic or aromatic anhydride or a substituted derivative thereof, and the amount in moles of anhydride being substantially equal to or slightly greater than the amount in moles of citric acid; (b) heating the reaction mixture to at least 60° C. for up to 45 minutes; (c) adding an amount in moles of fatty alcohol to the reaction mixture substantially equal to the amount in moles of the citric acid in the initial reaction mixture, the fatty alcohol having the formula R.sub.1 --OH where R 1 OH is selected from the group consisting of alcohols of the formula R.sub.2 --A--(O--R.sub.3).sub.x --OH (III) or R.sub.2 --(O--R.sub.3).sub.x--OH (IV) where R 2 is a hydrocarbon chain having 10 to 18 carbon atoms, A is an aryl group, R 3 is an alkyl chain having 2 to 4 carbon atoms, and x is an integer from 1 to 7; and (d) heating and continuously distilling the reaction mixture and fatty alcohol forming a monoester of citric acid.