A QUANTITATIVE STUDY OF SUBSTITUENT EFFECTS ON OXIDATIVE CYCLIZATION OF SOME 2-METHYLSUBSTITUTED ALDEHYDES - THIOSEMICARBAZONES INDUCED BY FERRIC-CHLORIDE

In order to gain further mechanistical information about tbe cyclizati on of thiosemicarbazones and thiosemicarbazone-type substrates induced by metallic salts as oxidizing agents, we performed the synthesis of substrates 1a-s and a kinetic study of the oxidative cyclization of 1 to 5-imino-Delta(2)-1,3,4,thiadiazole 2 and 1,2,4-triazoline-5-thione 3 derivatives induced by methanolic ferric chloride solutions. The res ults of cyclization were compared to those of corresponding semicarbaz ones. The kinetic data were analyzed by means of the Hammett's equatio n and rho values discussed.