Kinetics of oxidation of nicotinic and isonicotinic acids by permanganate in acidic medium

Abstract

The most important feature of this study of the oxidation of nicotinic acid (Nic) and isonicotinic acid (lnic) by permanganate in acidic medium is the complete solution of the rate laws (A) for Nic and (B) for Inic by varying [H + ] over an extended concentration range. - d[MnO 4 - ]/dt = {k 0 K 1 [H + ] + k K 1 K 2 [H + ] 2 + k 3 K 1 K 2 K 3 [H + ] 3 }[MnO 4 - ][Nic] 0 / {1 + K 1 [H + ] + K 1 K 2 [H + ] 2 ] (A) - d[MnO 4 - ]/dt = {k K 2 [H + ] + k 3 K 2 K 3 [H + ] 2 } [MnO 4 - ] t [lnic]/{1 + K 2 [H + ]} (B) The relationships of the rate parameters and their values are as follows: K 1 (NC 5 H 4 COO - + H + = HN + C 5 H 4 COO - [B]), 1.78 × 10 4 (30) (Nic); K 2 (HN + C 5 H 4 COO - [B] + H + = HN + C 5 H 4 COOH [C]), 46.2 (30) (Nic), 33.6 (40) (Inic); k s ([B] + MnO 4 - → products), 1.56 x 10 -3 L mol -1 s -1 (30) (Nic); k ([C] + MnO 4 - → products), 1.64 x 10 -2 (30) (Nic), 1.68 x 10 -3 L mol -1 s -1 (40) (lnic) and k 3 K 3 ([C] + HMnO 4 → products), 2.02 x 10 -2 (30) (Nic), 3.2 x 10 -3 L 2 mol -2 s -1 (40°) (inic). The reactivity of Nic was greater than that of Inic.