| 摘要 |
Sulphamic acid is prepared by reacting urea, H2SO4, and SO3 in suspension in a halogenated hydrocarbon, preferably an aliphatic hydrocarbon having 1-6 C atoms, e.g. tetrachloroethane, or tri-, or tetra-chloroethylene. Stoichiometric quantities of reactants may be used, or an excess of not more than 5% of H2SO4 and/or SO3, which may both be present in the form of oleum, e.g. 40-45%. The urea should be added in portions so that the temperature is 40 DEG -50 DEG C. for the first half of the addition, and 50 DEG -60 DEG C. for the second. When the urea addition is completed after say 1-2 hours the temperature is raised to 90 DEG -110 DEG C. The mixture is stirred throughout, and finally cooled, when the balls of sulphamic acid (0,5-1,5 mm.) are separated by filtering or centrifuging. The sulphamic acid is dried in an air stream at 100 DEG C., and the mother liquor may be reused after regeneration, if necessary, by water washing and distillation. |
