INTERACTION OF 3,4-DIPHENYL-1,2,5-THIADIAZOLE 1,1-DIOXIDE WITH PROTONDONOR SOLVENTS

The UV spectra of 3,4-diphenyl-1,2,5-thiadiazole 1,1-dioxide (I) and t hat of its thiadiazoline and thiadiazolidine derivatives were measured in several aprotic and protic solvents. Strong specific interactions of I with protic solvents are observed and the formation of stable car binolamine type derivatives of I with methanol or ethanol is proposed. Spectroscopic data (UV, H-1 and C-13 NMR) and electrochemical evidenc e for their formation are given and a new thiadiazoline derivative of I 3-ethoxy-2-methyl-3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide) was synthesized. The equilibrium constant for the reaction of 1 with ethan ol is reported.