Phenylhydrazine → 3,5-Dimethyl-1-phenyl-pyrazol-4-acetic acid methyl ester

Participants

Reaction Steps

10 grams of a 50% suspension of sodium hydride in paraffin oil were dispersed in 100 milliliters dimethyl formamide and to the dispersion, thus obtained, 20 grams acetylacetone were added drop by drop. After completion of the evolution of hydrogen, 31 grams bromoacetic acid methyl ester were added dropwise with stirring to the reaction mixture at room temperature and the mixture was stirred for another 15 hours. The solvent was then distilled off, the residue was taken up in ether, and the ether solution extracted with water. By distillation of the ether solution 26 grams of crude 3,3-diacetylpropionic acid-methyl ester having a Kp10 of 112°-117° C. were obtained. The distilled 3,3-diacetyl-propionic acid methylester was reacted with 16.5 grams phenylhydrazine and 9 grams glacial acetic acid in 100 milliliters ethanol and the reaction product was recovered by the method described in Example (1a) above. 28 grams of crude 3,5-dimethyl-1-phenyl-pyrazol-4-acetic acid methyl ester were obtained, which, after recrystallization from a mixture of ethanol and wter, melted at 63°-64° C.

Provenance & Evidence