GB831067A - Improvements in or relating to uracil derivatives - Google Patents

Abstract

Uracil- and substituted uracil-5-sulphonyl halides are prepared by reacting a uracil as hereinafter defined with a halosulphonic acid at a temperature of at least 60 DEG C. for at least 6 hours. Preferably, at least 5 mols. of the halosulphonic acid are used per mol. of the uracil at temperatures from 60-120 DEG C. The uracil employed may be any pyrimidine-2 : 4-dione capable of reacting with a halo sulphonic acid to produce a carbon-sulphur bond at the 5-carbon position; the nitrogen atom in the 1-and/or 3-positions may carry alkyl or substituted alkyl radicals, e.g. methyl or chlormethyl radicals and the 6-carbon atom may bear an alkyl or substituted alkyl radical, in which the substituents are non-interfering with the halosulphonation in the 5-position, or may be attached to halogen, oxygen, sulphur or nitrogen and the latter three elements may themselves bear a hydrogen atom or an organic radical such as an alkyl, aryl or heterocyclic radical. Chlorsulphonic acid is preferred as reagent but the bromo- and fluoro analogues are also mentioned. The uracil-5-sulphonyl halide may be reacted with water, an alcohol, a phenol or an amine, e.g. dimethylamine or aniline to yield the corresponding sulphonic acid or derivative thereof. The uracil-5-sulphonyl halides may be reduced to the corresponding uracil-5-mercaptans by means of metallic zinc in an acidic medium and the mercaptan can be oxidized to the corresponding di-(uracyl-5-yl) disulphide, for example, by treatment with iodine in a strong aqueous alkaline medium or by refluxing with aqueous sulphuric acid. Examples describe the preparation of uracil-5 sulphonyl chloride and its conversion into the corresponding sulphonic acid and its sodium and toluidine salts and phenyl ester, and the sulphonanilide, N : N-dimethyl sulphonamide and 5-mercapto uracil and of 6-amino-uracil-5 sulphonyl chloride and the corresponding sulphonanilide.