The mechanism of the free-radical-induced chain isomerisation of 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide

Abstract

The cis-trans isomerisation of 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2) has been studied by pulse and steady-state radiolysis techniques. A free-radical chain-isomerisation mechanism is proposed. Initiation involves production of nitro radical-anions from cis-AF-2 with subsequent isomerisation to give the trans-AF-2 radical. Propagation of the chain reaction occurs via electron transfer between the isomers and their radical-anions, disproportionation of the radicals representing the main chainterminating step. Oxygen acts as an efficient inhibitor of isomerisation by electron-transfer reaction with the nitro radical-anions. Computer simulations using the Gear numerical integration algorithm show this mechanism to match the observed results closely.