2,1,3-Thiadiazole benzo

C. 1,2,3-Benzothiadiazole 1,1-dioxide. Caution 1,2,3-Benzo-thiadiazole 1,1-dioxide in the solid slate can explode spontaneously, particularly on being warmed, jolted, or scratched. For most purposes it need not be isolated, but can be used in solutions, which are relatively safe. Any operations involving the solid material should be done very carefully, using good shielding. 

An interesting rearrangement was found by Davies and Kirby (1967) in the diazo-tization of 7-amino-benzothiazole (6.68). As Scheme 6-45 shows, the diazonium ion formed initially rearranges under hydrolytic conditions into 7-amino-l,2,3-benzo-thiadiazole (6.69). 

Research on the fluorination of aromatic amines has provided access to 4-fluoro-2,l,3-benzo-thiadiazole (77). Treatment of 4-amino-2,l,3-benzothiadiazole (1) with nitrosonium tetra-fluoroborate (NOBF4), followed by heating of the resulting diazonium salt, gave the aryl fluoride (77) in 23% yield <92SC73>. 

In the presence of alkynes the thieno[3,4-c][l,2,5]thiadiazoles (78) give benzo-thiadiazoles (81) in good yield. These products are formed by desulfurization of the primary adducts (82) (79TL4493, 80JOC2956). Cycloaddition with 6,6-diphenylfulvene has also been reported (80CL1031). 

Benzothiadiazole is oxidized by ozone, potassium permanganate,and chromic acid which all lead to the dicarboxylic acid (8). In the ozonolysis the intermediate crystalline ozonide is decomposed to l,2,5-thiadiazole-3,4-dicarboxaldehyde (isolated as the semicarbazone) as well as 8. Permanganate oxidation has been applied to a number of derivatives of 7, among them being the 5-methyl, 4-nitro, and 4,7-dichloro derivatives. In some cases, particularly in the permanganate oxidation of 4-nitro-2,l,3-benzo-thiadiazole, the yield of 8 is much higher than in the oxidation of the unsuhstituted compound (7). 

Thiete structures have been suggested as fragmentation products in the mass spectra of a thietane fused to a 3-lactam, an ortho disulfide of a thiolbenzoate ester, -propanethiol, thiirane carboxylic acid esters, isothiazoles, thiazoles, 1,3-dithiole 2-thiones, 1,3-dithiolene-2-ones, S-ethyl thio-benzoate, and thianaphthene sulfones. Tetramethylthiete may have been formed on thermolysis of the p-toluenesulfonyl-hydrazone of 2,2,4,4-tetramethyl-3-thietanone. " Thiete 2-thione may be an intermediate in the decomposition of 1,2-ditholium salts by the action of bases. " 2,2-Diphenyl-2H-thiete is suggested as an intermediate in the reaction of diphenyldiazomethane with 1,2,3-benzo-thiadiazole which yields 9-phenylthioxanthene and three other products. ... 

Colella S, Melcarne G, Mazzeo M, Gigli G, Grisorio R, Suranna GP, et al. Synthesis, characterization and photovoltaic properties of random poly(arylene-vinylene)s containing benzo-thiadiazole. Polymer 2011 52(13) 2740-6. 

Bo et al. reported the synthesis of a series of D-A alternating conjugated polymers P24-31 with 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit by Suzuki polyeondensation of dibromo monomers and 5,6-bis(octyloxy)benzo-thiadiazole based diboronic acid pinacol ester. P24) with a of 102 kg mol and a PDI of 1.66, gave a PCE of 5.08% in devices with P24 PC7iBM as the active... 

Acetanilides, benzoyl-colour couplers in colour photography, 1, 372 Acetanilides, pivaloyl-colour couplers in colour photography, 1, 372 Acetazolamide — see l,3,4-Thiadiazole-2-sulfonamide, 5-acetamido-Acetic acid, acetamidocyano-ethyl ester, 1, 307 Acetic acid, 2-acylphenyl-isochroman-3-one synthesis from, 3, 858 Acetic acid, 3-benzo[6]thiophenyl-biological activity, 4, 912 Acetic acid, l,2-benzoxazol-3-yl-electrophilic substitution, 6, 48... 

The structure of the isomeric benzo-l,2,3-thiadiazole 11.30 is unknown, but the 1 1 adduct with AsFs (11.31) has been structurally characterized. The AsFs molecule is coordinated to the carbon-bonded nitrogen atom. Cycloocteno-l,2,3-selenadiazole is an effective source of selenium for the production of semi-conductors such as cadmium selenide." ... 

Die Elektrolyse von Benzo-l,2,5-thiadiazol bzw. -selenadiazol in waBriger Losung an Quecksilber fiihrt ebenfalls zu 1,2-Diamino-benzol4 ... 

Very many fused 1,2,5-thiadiazoles, and some fused 1,2,3-thiadiazoles, have been prepared the two typical reactions are illustrated (Scheme 8). The first is exemplified by the synthesis of numerous benzo- and hetero-fused 1,2,5-thiadiazoles by Carmack and co-workers,68 and by Hartman s group 69 an example of the second is the preparation of l,2,3-thiadiazolo[4,5-d]-pyrimidines.70... 

The bond lengths and bond angles found for benzo-l,2,3-thiadiazole by X-ray diffraction are listed in Table 3. These values are quite close to those published for a substituted 1,2,3-benzothiadiazole <1984CHEC(6)447>. 

---