GB774823A - Improvements in and relating to a process for producing benzenesulfonylguanidines - Google Patents

Abstract

Benzenesulphonylguanidines of the general formula R.C6H4SO2NHC(: NH)NH2, in which R is a hydrogen atom, a para-methyl or a para-amino group are prepared by reacting a sulphonamide R.C6H4SO2NH2 with calcium cyanamide in the presence of water under influence of heat. The reaction may be carried out in the presence of water as such, e.g. in aqueous suspension, with or without the addition of a compound yielding water under the conditions of the reaction, preferably by boiling; or in a melting operation in the presence of a compound decomposing under the reaction conditions to yield water, preferably at from 150 DEG to 200 DEG C. Compounds yielding water include compounds containing water of crystallization, inorganic acids containing water, ammonium salts of organic aliphatic acids, organic amides and aliphatic polyalcohols. The melting procedure is facilitated by the addition of substances which will maintain the reaction mixture in a fluid, stirrable state, e.g. metal salts of acids, such as calcium chloride or sodium acetate, phenol ethers such as anisole, and inorganic acids such as phosphoric acid or boric acid. In either procedure metal salts such as sodium chloride, calcium chloride, aluminium chloride, zinc chloride and sodium bromide may be added to stabilize the product and any unreacted sulphonamide. In the melting process the reaction mixture may subsequently be dissolved in hot water containing an alkali metal carbonate and filtered, and the filtrate cooled, when the required product crystallizes. In examples of the melting procedure the following substances are added to a reaction mixture of sulphanilamide and calcium cyanamide: (1) no additions (comparative example); (2) commercial calcium chloride and crystalline sodium acetate; (3) CaCl2.2H2O and sodium chloride; (4) CaCl2, NaBr and crystalline CH3COONa; (5) acetamide; (6) CaCl2 and acetamide; (7) crystalline oxalic acid (or boric or phosphoric acid) and CaCl2; and (8) anisole and CaCl2.2H2O. In further examples: (9) sulphanilamide, calcium cyanamide and water are heated, sodium carbonate is added, the mixture is filtered and caustic soda is added to the filtrate when sulphaguanidine separates; CaCl2 with or without acetamide may also be added; (10)-(12) MgCl2 and CaCl2, NaBr with CaCl2 and acetamide, and ammonium acetate are added in the process of (9); (13) benzene sulphonamide, calcium cyanamide, CaCl2 and acetamide in the melt process give benzene sulphonyl guanidine; (14) p - toluenesulphonamide, calcium cyanamide, CaCl2 and acetamide give p-toluene-sulphonylguanidine