反应详情

22.9 g of 5-(5-chloro-3-fluoro-2-pyridyl)-2-methyl-[2H]-pyrazole-3-carboxylic acid ethyl ester (Example P19) are introduced together with 19.9 g of sodium acetate into 300 ml of glacial acetic acid at a temperature of 65° C. With stirring, 6.3 g of chlorine gas are passed over the solution at that temperature in the course of 1 hour. The reaction mixture is then poured into 2.5 liters of ice-water and subsequently stirred for 20 minutes. The resulting precipitate is filtered off, washed with ice-water and then dried in vacuo at 50° C. 24.4 g of the desired title compound are obtained in the form of a yellow solid having a melting point of 77-79° C.

1. customare passed over the solution at that temperature in the course of 1 hour
2. stirringsubsequently stirred for 20 minutes
3. filtrationThe resulting precipitate is filtered off
4. washwashed with ice-water
5. customdried in vacuo at 50° C