Ethanol → 1-(1-ethoxyethyl)-3-((E)-styryl)-1H-thieno[2,3-c]pyrazole-5-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

2 cm3 of ethanol, 2 cm3 of water and 0.60 g (10.8 mmol) of potassium hydroxide are successively added with stirring to a solution of 2.0 g (5.4 mmol) of ethyl 1-(1-ethoxyethyl)-3-((E)-styryl)-1H-thieno[2,3-c]pyrazole-5-carboxylate in 15 cm3 of tetrahydrofuran. The reaction medium is heated at a temperature in the region of 85° C. for 5 hours and is then cooled to a temperature in the region of 25° C. and concentrated to dryness under reduced pressure (2.7 kPa) at a temperature in the region of 40° C. The residue is dissolved in 150 cm3 of water and extracted with twice 100 cm3 of diethyl ether. The aqueous phase is acidified to a pH of about 5 by adding solid citric acid, and is then extracted with three times 100 cm3 of ethyl acetate. The organic phases are combined, dried over magnesium sulfate, filtered and then concentrated to dryness under reduced pressure (2.7 kPa) at a temperature in the region of 40° C. 1.8 g of 1-(1-ethoxyethyl)-3-((E)-styryl)-1H-thieno[2,3-c]pyrazole-5-carboxylic acid are thus obtained in the form of a pale yellow solid melting at 160° C. Mass spectrum (EI): m/z 342 [M+], 270 (base peak): [M+] —C2H5—O—CH—CH3.

Provenance & Evidence