13C NMR Study of Annular Tautomerism of Azoles in the Solid State

The 13c chemical s h i f t s o f 1.2,4-triazole, t e t r a z o l e , indarale, benrimidazole, and b e m o t r i a r o l e have been obtained from s o l i d samples usmg the CP-MAS technique.They are discussed i n connection w l t h the annular prot o t r o p l c t a u t m e r i s m of these azoles and benzazales.A case o f f u n c t i o n a l t a u t m e r i m , t h a t o f benroxazol~din-2-thione, and a case o f non-prototropic t a u t m e r i m , t h a t o f 1-trimethylsllylbenzimidazole, are a l s o studied.