| 摘要 |
<p>5-amino-1,2,3-thiadiazoles of the formula <IMAGE> I are made by reacting halogenoacetaldehydes of the formula X-CH2-CH=O II with hydrazine derivatives of the formula H2N-NH-COR III preferably in an aqueous medium or in a mixture of an aqueous medium with organic solvents so as to form acylhydrazones of the formula X-CH2-CH=N-CH-CO-R IV whereupon the latter are reacted with thionylchloride of the formula SOCl2 V whereby 5-halogeno-1,2,3-thiadiazoles are formed which are then reacted with ammonia preferably in the presence of a catalyst such as a mineral acid or Lewis acid whereby the desired product is obtained. The products are useful in making plant protection agents and herbicides such as the 1,2,3-thiadiazolyl-urea derivatives.</p> |
