In the above process of riilg closure, the hydrazo compound acts obviously in the dithiol form, as otherwise the formation of the thiodiazole compound is inexplicable. The di-acetyl compound loses its acetyl groups when hydrolyzed by boiling with hydrochloric acid, and the unsubstituted di-imino-tetrahydro-thiodiazole is generated. This method of ring closure is of special significance from the point of view of its applicability with all alkyl and aryl ...