The synthesis and thermolysis of imidazole quaternary salts

The pyrolysis of imidazolium halides substituted on the nitrogen atoms by alkyl or aryl groups leads to 1-substituted imidazoles. Differing substituents cleave at different rates, while the nature of the anion and the influence of substituents at C4 modify the reaction products. Tetraphenylborate and perchlorate salts fail to dealkylate. An SN2 (or SN2?) mechanism appears to be the most likely for the process.