[C:1]([C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][N:5]=1)(=[O:3])[CH3:2].OO.C(OCC)(=[O:14])C.CCCCCC>C(O)(=O)C.CO>[C:1]([C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][N+:5]=1[O-:14])(=[O:3])[CH3:2]To a solution of 2-acetylpyridine (0.3 mol) in 150 ml of glacial acetic acid was added with stirring 30% hydrogen peroxide (0.32 mol) and the mixture was allowed to react at 60-65° C. for 16 hours. An additional 3.3 ml of 30% hydrogen peroxide was added, and the mixture was allowed to react at 70° C. for 2 hours. After cooling, the water was removed by evaporation at reduced pressure to leave a crude liquid residue which was taken up in an equal volume of 50:50 ethyl acetate and hexane, and the components were separated by chromatography on 330 g of silica gel. Gradient elution starting with 50:50 ethyl acetate/hexane to 100% ethyl acetate and then to 5% methanol gave 13.48 g (33% yield) of 2-acetyl-pyridine-N-oxide. 1H NMR (CDCl3): 2.81 (singlet (s), 3H, CH3), 7.34 (multiplet (m), 2H, H4 and H5), 7.71 (doublet (d), 1H, H3), and 8.22 ppm (d, 1H, H5); 13C NMR (CDCl3): 31.3 (CH3), 125.9, 127.4, 128.6, 141.2, and 195.7 ppm (C═O); mass spectrum (DCl) M+H=138 m/e; IR (film) |max 1686 cm−1 (C═O).
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