The chemistry of N-substituted benzotriazoles. Part 5. Reactions of benzotriazole with aldehydes and thionyl chloride—formation of (benzotriazol-1-yl)-1-chloroalkanes and bis(benzotriazolyl)alkanes

Reaction of benzotriazole with an excess of aliphatic aldehydes and thionyl chloride in refluxing chloroform gives the corresponding 1-(benzotriazol-1-yl)-1-chloroalkanes. Products with an α-hydrogen next to the chlorine-bearing carbon atom gradually eliminate hydrogen chloride with time or when heated. Nucleophilic displacements of the chlorine atom are described. Reaction of 2 mol equiv. of benzotriazole with 1 mol equiv. of aromatic or aliphatic aldehydes and an excess of thionyl chloride yields the corresponding bis(benzotriazol-1-yl)methylarenes and 1,1-bis(benzotriazol-1-yl)alkanes respectively; usually some of the corresponding 1-(benzotriazol-1-yl)-1-(benzotriazol-2-yl)alkanes are also formed. The 1-(benzotriazol-1-yl)-1-chloro-1-arylmethanes spontaneously react further to give bisbenzotriazolyl compounds.