GB653522A - Improvements in or relating to the production of guanadine sulphates - Google Patents

Abstract

Guanidine sulphates are prepared by the reaction of sulphamic acid or one of its salts with urea. The reactants are fused and then heated to a suitable temperature for a short period to permit the reaction to occur. Suitable high-boiling, inert solvents and/or diluents may be used. The preferred temperature of the reaction is in the range 190-300 DEG C. Sulphamic acid salts mentioned as starting materials are ammonia, aluminium, potassium, sodium, barium, calcium, magnesium and like sulphamates and also sulphamic acid addition salts of the amines of the aliphatic, carbocyclic and heterocyclic series such as methylamine, diethylamine, di - n - dodecylamine, aniline, morpholine sulphamates. Preferably 1 mol. of urea is used to 1/2 -3 mols. of sulphamate. The product is then predominantly diguanidine sulphate but the more acidic monoguanidine sulphate may be prepared from it by acidifying the diguanidine sulphate with sulphuric acid. A less soluble guanidine salt, e.g. a picrate, carbonate or phosphate may be obtained by the action of the appropriate acid on the sulphate. Free guanidine may be obtained by dissolving the dry reaction mixture in an alcohol, adding excess potassium hydroxide and obtaining the guanidine from solution by the usual methods. In the examples, guanidine sulphate is prepared by reaction p between (a) urea and ammonium sulphamate; (b) urea and sulphamic acid; (c) urea and sodium sulphamate (prepared by action of sulphamic acid on sodium hydroxide); (d) urea and calcium sulphamate (prepared by the action of sulphamic acid on calcium hydroxide); in this example the guanidine sulphate is treated with picric acid to give guanidine picrate; (e) urea and dodecylamine sulphamate (prepared by the action of dodecylamine on sulphamic acid).