| 摘要 |
PURPOSE:To provide a 5-chloropyrazole derivative useful as an intermediate of a new pyrazolesulfonylurea derivative valuable as a selective herbicide. CONSTITUTION:The 5-chloropyrazole derivative of the formula (A is a lower alkyl; R1 is H or a lower alkyl), e.g. ethyl 5-chloro-1-methylpyrazole-4- carboxylate. This exemplified compound is obtained from a filtrate obtained by reacting diethyl ethoxymethylenemalonate with methylhydrazine, reacting the resultant ethyl 5-hydroxy-1-methylpyrazole-4-carboxylate with phosphorous oxychloride, distilling off excessive phosphorous oxychloride under vacuum, pouring the residue into ice water and filtrating the deposited crystal. A pyrazolesulfonylurea derivative synthesized from this compound has a strong herbicidal effect on various kinds of weeds in any case of soil drench or foliage spray and exhibits a high safety to rice, wheat and corn as important crops. |
