5-Amino-1-phenylpyrazole

16078-71-0

826-85-7

General procedure for the synthesis of 5-amino-1-phenylpyrazole-4-carboxylic acid from ethyl 5-amino-1-phenylpyrazole-4-carboxylate: Step 1: Synthesis of 1-phenyl-1H-pyrazol-5-amine (F1) 5-Amino-4-ethoxy-1-phenylpyrazole (1 eq.) was dissolved in 36% hydrochloric acid solution (30 eq.) and the reaction mixture was stirred under reflux conditions overnight. After completion of the reaction, the mixture was cooled to room temperature, slowly poured into ice water and the pH was adjusted to basic with ammonia. The mixture was extracted with dichloromethane (3 times) and the organic phases were combined. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to remove the solvent to give a light yellow oily product in 94% yield. Mass spectrometry (electrospray positive ionization mode): the theoretical molecular weight of C9H9N3 was 159, and the measured value was 160 (M+H)+.