Investigation of 2,1,3-thia-and 2,1,3-selenadiazoles

Abstract

The position of entry of the substituent in the electrophilic substitution of naphtho[1,2-d][2,1,3]thiadiazole depends on the nature of the attacking reagent: depending on the experimental conditions, 5-chloro and di,- and trichloro-substituted derivatives and 4-bromo and dibromo derivatives are formed during chlorination and bromination. In the absence of a catalyst, naphthothiadiazole is chlorinated by sulfuryl chloride to give 5-chloronaphthodiazole; 5-bromonaphthothiadiazole is formed with N-bromosuccinimide in the presence of anhydrous aluminum chloride. The 6-, 7-, 8-, and 9-amino derivatives of naphthothiadiazole are converted to the corresponding chloro and bromo derivatives by the Sandmeyer reaction. Depending on the experimental conditions, 4-sulfo (or chlorosulfo) and disulfo (or dichlorosulfo) derivatives are formed in the sulfonation and chlorosulfonation of naphthothiadiazole. As in the naphthalene series, the sulfo (or chlorosulfo) group can be replaced by chlorine (or bromine). Phthalic acid is obtained in the oxidation of 4-bromonaphthothiadiazole with potassium permanganate.