Toluene → 1H-Pyrazole--toluene (1/1)

A 2000-ml three-neck flask was equipped with a dropping funnel and a thermometer and sealed under a nitrogen balloon. Into this flask, 36.0 g of water, 6.4 g of sodium hydroxide, 400 ml of toluene and 24.0 g (0.52 mol) of monomethylhydrazine were placed. The resulting solution was cooled, with stirring, to −10° C. or lower in a low-temperature thermostat whose temperature was set to −15° C. Then, 375 g of the water-washed DFAAE-toluene solution (DFAAE: 0.11 mol) was gradually dropped into the flask through the dropping funnel in such a manner that the inside temperature of the flask did not exceed −10° C. After completion of the dropping, the solution was kept stirred for 1 hour at −12° C. The inside temperature of the flask was then raised to 0° C. The thus-obtained solution was separated with the addition of 400 ml of water. The organic phase was recovered by a separatory funnel and washed with 400 ml of water, thereby yielding 702 g of 9.7 mass % pyrazole-toluene solution.