GB644913A - Improvements in or relating to synthetic folic acid and related compounds and the preparation thereof - Google Patents

Abstract

Alkaline earth metal salts of pteridines of the general formula <FORM:0644913/IV (b)/1> wherein the group -COR is an amide group derived from glutamic acid or derived from a glutamic acid formed through a peptide linkage to a chain of one or more glutamic acid residues joined by peptide linkages, are obtained by treating a crude reaction mixture containing a pteridine of the above formula by adding a water-soluble alkaline earth metal compound, e.g. a barium or calcium compound to an aqueous solution of the mixture, preferably at an alkaline pH, e.g. at a pH above about 8, to convert the pteridines in the mixture to alkaline earth metal salts and separating the insoluble matter from the aqueous solution containing the soluble alkaline earth metal salt of the pteridine. The aqueous solution may contain not more than about 25 per cent by weight of a water-miscible alcohol or such alcohol is added to the aqueous reaction mixture so as to produce a concentration of not more than about 25 per cent by weight thereof. The aqueous solution may contain from 5 to 20 per cent by weight of the alcohol and preferably not more than about 10 per cent by weight. Suitable water-miscible alcohols mentioned are methyl, ethyl and isopropyl alcohols. The solution containing the alkaline earth metal salt of the pteridine may be treated with an acid which will precipitate the alkaline earth metal as an insoluble salt, and thereafter the water-soluble aqueous fraction is extracted with butanol to remove butanol soluble products. In an example, N - [4 - {[(2 - amino - 4 - hydroxy - 6 - pyrimido[4, 5-6] pyrazyl) methyl] amino} benzoyl] glutamic acid, also known as folic acid, is separated from a crude mixture.