Title: Comparative rate study on the oxidation of nicotinamide and isonicotinamide by permanganate in acidic medium
Abstract: A comparative rate study on the oxidation of nicotinamide and isonicotinamide by potassium permanganate has been carried out in acidic solutions over an extended [H + ]-range (1x 10 -5 -1.0 mol L -1 ). Under the similar reaction conditions, the oxidation of pyridine is imperceptible. Further, in the absence of acid none of the two amides Is oxidized and in both cases, the N-protonated amide species appears to be reactive. For nicotinamide, the results are in agreement with the two-term rate law (A). The oxidation product was corresponding N-oxide. On the other hand, the oxidation of isonicotinamide follows a simpler rate law (B). The values of k 0 , K and k,K, for nicotinamide were found to be 5.5 x 10 -3 L mol -1 s -1 , 1.8 x 10 4 and 1.0 x 10 -2 L mol -1 s -1 , respectively at 35 °C. And for isonicotinamide, the k 0 and K values were 4.4 x 10 -3 L mol -1 s -1 and 5.6 x 103 respectively at 35 °C. The oxidation of nicotinamide is faster than the oxidation of isonicotinamide. It appears that the presence of -CONH 2 group at position 3 activates the ring nitrogen more for oxidation than the presence of this group at position 4.