Pulse radiolysis studies on reactions of α-hydroxyalkyl radicals with nicotinamide and 6-methyl nicotinic acid

Abstract

Reactions of α-hydroxyalkyl radicals derived from 2-propanol, ethanol and methanol with nicotinamide (NICAM) and 6-methyl nicotinic acid (6-MNA) were studied at various pHs using pulse radiolysis technique. It is found that α-hydroxyalkyl radicals react with NICAM and 6-MNA at pHs when nitrogen is in the protonated state. In these reactions, radical adducts of NICAM/6-MNA with α-hydroxyalkyl radicals are formed which have absorption maxima at about 340–350nm which subsequently decay to give pyridinyl type of radicals of NICAM and 6-MNA having λmax at 410nm. Rate constants for the reactions of (CH3)2COH, CH3CHOH and CH2OH radicals with NICAM and 6-MNA were found to have linear dependence on reduction potentials of corresponding α-hydroxyalkyl radicals. Adducts formed in the reactions of CH3CHOH and CH2OH radicals with both NICAM and 6-MNA decayed slowly compared to the decay of adduct formed in reactions with (CH3)2COH radicals.