Studies on 2-Benzimidazolethiol Derivatives. III : Pyrolysis of 2-(ω-Hydroxy-and ω-amino-alkyl)-Derivatives and 1-(2-Diethyl-aminoethyl)-2-chlorobenzimidazole

Abstract

When 2-(ω-hydroxyalkylthio)benzimidazole is heated, the most facile decomposition occurs when there are 2-methylene groups in the alkyl and 2-benzimidazolinone is formed. This decomposition becomes increasingly difficult with increase in the number of methylenes with the exception of four methylenes. Heating of 2-(2-aminoethylthio)benzimidazoles results in rearrangement and bis[2-(2-benzimidazolyl)aminoethyl]disulfide derivatives are formed. In either case, formation of a spirane compound as an intermediate was confirmed. Heating of 1-(2-diethylaminoethyl)-2-chlorobenzimidazole results in the formation of 1-ethyl-2, 3-dihydroimidazo[1, 2-α]benzimidazole. These pyrolysis and heat rearrangement reactions are all due to the electron-attracting nature of the carbon atom in the 2-position of the benzimidazole ring.