| 摘要 |
<p>O-Methyl-isourea hydrogen sulfate is prepared from cyanamide, methanol, and sulfuric acid in a yield of better than 90% when crystalline cyanamide is added to a mixture of sulfuric acid and methanol containing 50 - 150 parts by weight methanol per part sulfuric acid and holding the resulting composition at -10 DEG to 20 DEG C. The recovered O-methyl-isourea hydrogen sulfate is further converted to O-methyl-isourea sulfate with yields greatly exceeding 50%, and even 80%, by holding a mixture of approximately equimolar amounts of cyanamide and of the hydrogen sulfate in a liquid medium essentially consisting of methanol at 5 DEG to 40 DEG C until the O-methyl-isourea sulfate is formed and can be recovered.</p> |
