GB822915A - Process for the preparation of condensation products of dialkyl xanthines and quaternary ammonium hydroxides - Google Patents

Abstract

Condensation products of the general formula <FORM:0822915/IV (a)/1> (wherein R1, R11 and R111 are alkyl groups of 1 to 3 carbon atoms, R is an alkyl group of at most 16 carbon atoms which may be substituted by hydroxy, alkoxy or aryl groups and X is a dialkylxanthinate radical or an 8-substituted dialkylxanthinate radical the alkyl groups of which each contain one to three carbon atoms) are prepared by reacting a sulphite, bisulphite or thiosulphate of a quaternary hydroxide of the general formula <FORM:0822915/IV (a)/2> in an aqueous medium with a dialkylxanthine or an 8-substituted dialkylxanthine HX, preferably with heating. Advantageously, an inert organic solvent such as isopropanol with or without benzene is added to the reaction mixture, and after the condensation reaction a substantial amount of the water present is removed by azeotropic distillation. In an example sulphur dioxide is bubbled into a cooled aqueous solution of choline, theophylline is added and the mixture is heated until SO2 evolution ceases, some of the water is distilled off under vacuum at 50 DEG to 55 DEG C. and then isopropanol is added and an azeotrope is distilled off under vacuum at 40 DEG C. to give, on cooling the remaining mixture, choline theophyllinate crystals. Reference is also made to the use of other quaternary ammonium hydroxides variously containing methyl, benzyl, hexyl, octyl, decyl and dodecyl radicals and to the use of other dialkylxanthines such as theobromine, paraxanthine and 8-chloro-, -bromo- or nitrodialkylxanthines in the process of the invention. Specification 376,443 is referred to.