Replacement of halogen by sulfur groups

Paritosh, D. R. et al Chem. Abs., 1994, 121, 35869j U.S. Pat. Appl. 42,229 Paritosh, D. R. etal., Phosphorus, Sulfur, Silicon Relat. Elem., 1994, 90(1-4), 175 This and several other compounds with fewer nitro groups and partial replacement of the spiro rings by halogen are patented as explosives. 

As has been pointed out, halogen in the 3-position in 1,2,4-thiadia-zoles is inert towards most nucleophilic reagents. Thus, under the usual conditions, 3-chloro-5-phenyl-1,2,4-thiadiazole cannot be hydrogenated catalytically to the parent base, and resists aminolysis, hydrazinolysis, and replacement of the halogen by cyano or thiol groups.178 It is unaffected by concentrated sulfuric acid at 100°, which converts the 5-analogs into the hydroxy compounds.178... 

Replacement of a labile halogen by the hydroxyl group, e.g., dinitrophenol from dinitrochlorobenzene, and many other similar preparations (see sulfur black T, page 337). 

Sulfur dissolved in DMF thionates in the presence of sec-amines methylene groups activated by a captor group. The halogen is then replaced by the amine, the overall sequence leading to thioamides. This is shown below for bromotrifluoro-acetone (Scheme 29, refs. 23, 24). 

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