PRODUCTION OF 2-PYRAZOLINE COMPOUND

PROBLEM TO BE SOLVED: To obtain a 2-pyrazoline compound safely and in high yield and with heat generation suppressed at the time of distillation for its purification by extracting the 2-pyrazoline compound with a hydrophobic nonhalogenated organic solvent after reaction of an α,β-unsaturated aldehyde with hydrazine. SOLUTION: After reaction of (A) an ct,[3-unsaturated aldehyde of the formula R-CH=CHCHO (R is H, an alkyl, pyridyl, furyl, cyclohexyl, phenyl, etc.) with (B) hydrazine in the presence of (C) acetic acid, (D) an aqueous alkaline solution, preferably ammonia water, is added to the resultant system, and the objective 2-pyrazoline compound of the formula is extracted with (E) a hydrophobic non-halogen-based organic solvent (preferably non-halogen-based carboxylic ester, aliphatic non-halogen-based aliphatic hydrocarbon, etc.). Preferably, the component C is used in a quantity of 0.5-2 equivalents based on the component B, and the component A in quantity of 0.7-1 equivalent based on the component B. Ammonia water of the component D in concentration of 20%, or higher is preferably used in a quantity of 1-3 equivalents based on the component C.