Pentyl nitrite → 2,3-Dichlorophenylglyoxal aldoxime

Participants

Reaction Steps

Potassium t-butoxide (239.7 g, 2.136 mol) was dissolved in t-butanol (1.5 liters) and allowed to stir at room temperature for 30 minutes. 2,3-Dichloroacetophenone (67.26 g, 0.356 mol) was added in one portion and the resulting mixture stirred overnight at room temperature. Amyl nitrite (83.41 g, 0.712 mol) was added slowly dropwise, with stirring. When the addition was complete the reaction mixture was stirred at room temperature for 2 hours and then heated at 50° C. for 2 hours. The solution was allowed to cool and stirred at room temperature overnight. The reaction mixture was poured into ice/water (1.5 liters), and the aqueous solution extracted with diethyl ether (3×500 ml). The aqueous phase was acidified with concentrated hydrochloric acid and allowed to stand at room temperature overnight. The solid which precipitated was filtered at the pump and dried under vacuum over anhydrous phosphorus pentoxide to give 2,3-dichlorophenylglyoxal aldoxime (57.3 g, 73.8%) as a brown solid. T.l.c. (SiO2 ; CHCl3) showed little impurity, but subsequent dehydration of the oxime showed that recrystallisation would be advisable. The oxime may be recrystallised from toluene, m.p. 109° C.

Provenance & Evidence