Production of pyrazole compounds useful as nitrification inhibitors and as intermediates for plant protection agents, dyes or polymers

摘要

Production of pyrazole or its derivatives comprises reacting pyrazolines, optionally formed in situ from alpha , beta -unsaturated carbonyl compounds and hydrazine derivatives, with an oxidizing agent selected from hydrogen peroxide, peroxydisulfate, t-butyl hydroperoxide, nitric acid, dinitrogen tetroxide, chlorine and hypochlorite at 50-120 deg C in the presence of iodine and/or an iodide or an iodine- and/or iodide-releasing compound. Production of compounds of formula (I) comprises reacting pyrazolines, optionally formed in situ from alpha , beta -unsaturated carbonyl compounds and hydrazine derivatives, with an oxidizing agent selected from hydrogen peroxide, peroxydisulfate, t-butyl hydroperoxide, nitric acid, dinitrogen tetroxide, chlorine and hypochlorite at 50-120 deg C in the presence of iodine and/or an iodide or an iodine- and/or iodide-releasing compound. R<1>-R<4> = H or optionally substituted 1-16C alkyl, aryl, aralkyl or cycloalkyl.