| 摘要 |
PURPOSE:To obtain 1-methyl-5-hydroxypyrazole useful as an intermediate for active component compound of herbicide, in high yield, by reacting a 3- alkoxyacrylic acid alkyl ester with methylhydrazine. CONSTITUTION:The objective 1-methyl-5-hydroxypyrazole is produced by reacting the 3-alkoxyacrylic acid alkyl ester of formula I (R<1> and R<2> are same or different lower alkyl) (e.g. 3-methoxyacrylic acid methyl ester) with methylhydrazine in a lower alcohol, preferably in methanol, etc. The starting compound of formula I can be produced e.g. by dealcoholating 3,3- dialkoxypropionic acid alkyl ester of formula III under heating in the presence of an acid.
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