Structure and properties of carbazic acid, its thio analogs, and their derivatives: I. Synthesis of 2-cyanoethyl 3,3-dimethylcarbazodithioate and itsreaction with propargyl bromide

Reaction of N,N-dimethylcarbazodithioic acid with acrylonitrile gave 2-cyan oethyl 3,3-dimethylcarbazodithioate, which exists in solution in neutral an d zwitter-ionic forms. Owing to this tautomerism, the pathway of its reacti on with an equimolar amount of propargyl bromide is unusual, and 5-(N,N-dim ethylhydrazono)-4,6-dithianon-8-ynonitrile hydrobromide is formed; its diss olution in water yields the free base.