1,3-dimethyl-2-substituted benzimidazolium salt can be easily prepared from carboxylic acid,o-phenylenediamine and methyl iodide via cyclization and quarternarization.It reacts with sodium hydrogen telluride in ethanol solution to produce 1,3-dimethyl-2-substituted benzimidazolidine.The reaction mechanism is discussed.Two benzimidazolidines are characterized by means of elemental analysis,IR and 1H NMR.Aldehydes are synthesized by hydrolysis reaction of the benzimidazolidines.Then,a novel synthetic method for aldehydes from the corresponding carboxylic acids via reduction-hydrolysis reaction of benzimidazolium salts is presented.The effect of 2-substituting group of benzimidazolium salts on the yield is discussed.
Dimethylbenzimidazolium iodide as an available convenient agent has been reacted with a Grignard reagent CH 3(CH 2) 5MgBr to give heptanal. The method need not neccessarily to isolate benzimidazolidine. The reaction mechanism is discussed.
