The course of reaction of 4-nitrobenzyl bromide and 5-nitrofurfuryl bromide with bases: Operation of anion-radical mechanism

Abstract

4-Nitrobenzyl bromide (I) - contrary to 5-nitrofurfuryl bromide (V) - does not react with hard bases in an electron-transfer chain reaction, giving instead product of SN2 reaction. However, its reaction with soft bases affords 1,2-bis(4-nitrophenyl)ethane (III) as anion-radical mechanism product. 5-Nitrofurfuryl bromide reacts with hard bases to give 1,2-bis(5-nitro-2-furyl)ethylene (VI) whereas with soft bases 1,2-bis(5-nitro-2-furyl)ethane (VII) is formed. The derivative VII on reaction with ethanolic NaOH reacts by α-E1cB mechanism under formation of the ethylene derivative VI. The derivative III does not react by this mechanism. The solvent and base effects on the formation of charge-transfer complexes in the initial stage of these reactions in relation to the reaction mechanism are discussed.