N-hydroxypyrazoles of the general formula I ##STR1## where R.sup.1, R.sup.2 and R.sup.3 may be identical or different and are each hydrogen or halogen, are prepared by a process in which a pyrazole of the general formula II ##STR2## where R.sup.1, R.sup.2 and R.sup.3 have the meanings stated for formula I, is reacted with an aliphatic or aromatic peroxocarboxylic acid, preferably in the presence of from 0 to 15 moles of an alkali metal hydroxide, alkaline earth metal hydroxide, alkali meteal carbonate or alkaline earth metal carbonate in such a way that the reaction temperature is from -5.degree. C. to 60.degree.C. The reaction can be carried out in water as a solvent or in a 2-phase system consisting of water and an inert organic solvent which is poorly miscible with water, in the presence or absence of a suitable phase transfer catalyst. The peroxocarboxylic acid can be prepared in the reaction mixture before the reaction from H.sub.2 O.sub.2 and an acyl halide or a carboxylic anhydride or can be used in the form of an alkali metal salt or alkaline earth metal salt.
通式I的N-羟基
吡唑化合物如下:其中R.sup.1、R.sup.2和R.sup.3可以相同也可以不同,每个都是氢或卤素。该化合物的制备方法包括以下步骤:将通式II的
吡唑化合物如下:其中R.sup.1、R.sup.2和R.sup.3的含义与通式I中所述相同,与脂肪族或芳香族过氧
羧酸反应,最好在存在0至15摩尔的碱
金属氢氧化物、碱土
金属氢氧化物、碱
金属
碳酸盐或碱土
金属
碳酸盐的情况下进行,使反应温度在-5°C至60°C之间。该反应可以在
水中作为溶剂或在由
水和与
水难以混合的惰性有机溶剂组成的两相体系中进行,可以在适当的相转移催化剂的存在或缺席下进行。过氧
羧酸可以在反应混合物中由H.sub.2 O.sub.2和
酰卤或
羧酸酐制备,也可以以碱
金属盐或碱土
金属盐的形式使用。