Carbon Dioxide → HCID 20449523, compound

Participants

Reaction Steps

Thiophosgene (11.5 g) was added slowly to a solution of 3-amino-1-(3-trifluoromethylphenyl)-2-pyrazoline (23 g) (prepared according to Reference Example 1 of European patent specification No. 22-578) in acetone (250 ml) at 0° in an atmosphere of carbon dioxide. The addition was completed in about 20 minutes and was then allowed to warm to room temperature for 1 hour. The resulting insoluble solid, the hydrochloride of the starting base, was filtered off and washed with fresh acetone. The combined filtrate and washings were evaporated in vacuo to give crude 3-isothiocyanato-1-(3-trifluoromethylphenyl)-2-pyrazoline as a gum (13 g) which subsequently crystallised. This compound was used directly without purification but the presence of the isothiocyanate group was confirmed by infra red spectroscopy which exhibited a broad band in the region of 2005 cm-1. This gum (3.8 g) was suspended in toluene (40 ml) and stirred during the addition of butylamine (1.5 g). When the gum changed into a colourless solid. After 2 hours, the mixture was warmed to about 35° for 10 minutes and then cooled back to room temperature. The resulting solid was collected, washed with a little fresh toluene and recrystallised from propanol in long prisms, m.p. 197°-198° of 3-(3-butylthioureido)-1-(3-trifluoromethylphenyl)-2-pyrazoline.

Provenance & Evidence