Patent GB-819019-A (GB)
Title: p-aminobenzene-sulphonyl-2-amino-oxazole derivative and its salts, and a process forthe production thereof
Filed: 1956-06-06
Abstract: The invention comprises p-aminobenzenesulphonyl - 2 - amino - 4,5 - dimethyl - oxazole of the formula <FORM:0819019/IV (b)/1> alkali metal, alkaline earth metal, ammonium and organic amine salts thereof, and the preparation thereof by reacting a benzene sulphonic acid having at the p-position a substituent transformable into an amino group such as an acylamino- or nitro-group or a halogen atom, or a reactive functional derivative of such a benzene sulphonic acid with 2-amino-4,5-dimethyl oxazole to form a bis-(p - substituted - benzene - sulphonyl) - 2 - amino - 4,5 - dimethyl - oxazole, or a mixture of p - substituted - benzene - sulphonyl - 2 - amino-4,5 - dimethyl - oxazole with the bis - product, and splitting of one p-substituted-benzene-sulphonyl radical from the bis-compound by hydrolysis or by reaction with a further mol. of 2 - amino - 4,5 - dimethyl - oxazole, and converting, if necessary, the substituent at the p-position into an amino group, and, when required, converting the resulting p-amino-benzene - sulphonyl - 2 - amino - 4,5 - dimethyl-oxazole into the required salt.  A suitable functional derivative of the substituted benzene sulphonic acid is the benzene sulphonyl chloride.  The condensation may take place in the presence or absence of condensation agents.  Preferably one mol. of 2-amino-4,5-dimethyl-oxazole is reacted with approximately 2 mols. of the substituted benzene sulphonyl chloride with the exclusion of water in an organic solvent free from hydroxy groups in the presence of approximately 2 mols. of anhydrous aliphatic amines consisting of one or more alkyl dimethylamines, the alkyl group of which contains 1 to 4 carbon atoms, and if desired, other tertiary amines the basicity of which is greater than that of trimethylamine and thereafter a benzene sulphonyl radical is split off from the resulting bis-(p-substituted benzene-sulphonyl) - 2 - amino - 4,5 - dimethyl - oxazole by hydrolysis or by reaction with another mol. of 2 - amino - 4,5 - dimethyl - oxazole, the substituent in the p-position relative to the sulpho group is, if necessary, transformed into an amino group and the p-aminobenzene-sulphonyl - 2 - amino - 4,5 - dimethyl - oxazole is if necessary transformed into an alkali metal, alkaline earth metal, ammonium and organic amine salts.  The substituent in the p-position relative to the sulpho group may be converted into an amino group by hydrolysis in the case of acylamino groups, by reduction in the case of a nitro group, and by treatment with aqueous or alcoholic ammonia at an elevated temperature and pressure in the case of a halogen substituent.  In the examples: (1) 2-amino-4,5 - dimethyl - oxazole is reacted with p-acetamino - benzene - sulphonyl chloride in the presence and in the absence of trimethylamine to form bis-(p-acetamino-benzene-sulphonyl) - 2 - amino - 4,5 - dimethyl - oxazole, and the bis compound is treated with hydrochloric acid and then with caustic soda to form the hydrochloride of p-aminobenzene-sulphonyl-2 - amino - 4,5 - dimethyl - oxazole and the free base respectively; (2) the reaction is carried out as in (1) but in the presence of pyridine to form a mixture of mono- and bis-(p - acetamino - benzene - sulphony) - 2 - amino-4,5-dimethyl-oxazole which are then treated as in (1); (3) 2-amino-4,5-dimethyl-oxazole is reacted with p-nitrobenzene sulphonyl chloride in the presence of trimethylamine to form bis-(p - nitrobenzene - sulphonyl) - 2 - amino - 4,5-dimethyl-oxazole, and the bis compound is treated with iron powder and hydrochloric acid then caustic soda to form p-aminobenzene-sulphonyl - 2 - amino - 4,5 - dimethyl - oxazole.