Abstract A study is presented for the synthesis of a series of 1-tert-butyl-3 (5)-(trifluoromethyl)- 1H-pyrazoles from the reaction of 4-alkoxy-1, 1, 1-trifluoro-3-alken-2-ones [CF 3 C (O) CH= C (R 1)(OR), where R= Et and R 1= H or R= Me and R 1= Me, Ph, 4-Me-C 6 H 4, 4-MeO-C 6 H 4, 4-FC 6 H 4, 4-Cl-C 6 H 4, 4-Br-C 6 H 4, 4-IC 6 H 4, fur-2-yl, thien-2-yl, or naphth-2-yl] with tert-butylhydrazine hydrochloride. When [BMIM][BF 4](1-butyl-3-methylimidazolium ...