反应详情

A solution of the 2-chloro-5-trifluoromethylpyridine (1.8 g, 0.01 mol) in methylene chloride (20 ml) was mixed with trifluoroacetic anhydride (15 g, 0.071 mol). The stirred solution was subjected to the dropwise addition of 30% aqueous hydrogen peroxide (1.4 g, 0.012 mol) over the course of 15 minutes. A mild exotherm ensued and the mixture was allowed to stir at ambient temperature for 1 hour. The solution was poured onto ice and extracted with 3×50 ml of ethyl acetate; the combined organic layers then were passed through a 1 inch pad of silica gel in a sintered glass funnel under suction. The eluate was evaporated and the residue was chromatographed on silica gel, eluting first with methylene chloride to remove unreacted pyridine and then with ethyl acetate to remove the product N-oxide weighing 1.8 g (90%) as an orange oil.

1. additionThe solution was poured onto ice
2. extractionextracted with 3×50 ml of ethyl acetate
3. customthe combined organic layers then were passed through a 1 inch pad of silica gel in a sintered glass funnel under suction
4. customThe eluate was evaporated
5. customthe residue was chromatographed on silica gel
6. washeluting first with methylene chloride
7. customto remove unreacted pyridine
8. customwith ethyl acetate to remove the product N-oxide weighing 1.8 g (90%) as an orange oil