Iminosulfur difluorides

By-products formed during the preparation of the title compound from (fluorocar-bonyl)iminosulfur difluoride, mercury (II) fluoride and bromine often react violently with water cleaning of equipment should initially be effected with carbon tetrachloride. 

On treatment with sulfur tetrafluoride, primary amines and compounds containing C-N multiple bonds are converted into iminosulfur difluorides. Sulfur tetrafluoride also undergoes addition to pcrfluoroalkenes and polyfluorovinyl ethers. 

Urea, melamine, cyanamide, dicyandiamide, and guanidine react at elevated temperatures with sulfur tetrafluoride to give (trifluoromethyl)iminosulfur difluoride (7) in 6-25% yield.172 In the presence of sodium fluoride at 25"C, urea is converted into fluorocarbonyliminosulfur difluoride (8), but at 50°C thiazyl fluoride (9) is the main product, both formed in ca. 60% yield. At higher temperatures, carbonyl difluoride (carbonic difluoride) and sulfur hexafluoride are the sole products of the reaction of urea with sulfur tetrafluoride.173... 

Guanidine, melamine and 1//-tetrazol-5-amine react with sulfur tetrafluoride under forcing conditions to give low yields of (trifluoromethyl)iminosulfur difluoride (3).172... 

When pentafluoroethylamine, which is stable only at low temperatures, is mixed with sulfur tetrafluoride, and the mixture is allowed to warm slowly from — 196 to 25 C in the presence of excess cesium fluoride, (pentafluoroethyl)iminosulfur difluoride (4) is obtained in 40% yield.198... 

Using an analogous procedure, 2-(trifluoromethyl)-l,3-dioxolan-2-amine and -l,3-dithiolan-2-amine can be converted into the corresponding iminosulfur difluorides 5 cesium or sodium fluoride may be used as the base but the highest yields (ca. 80%) are obtained in the presence of triethylamine.199... 

Hcxafluoropropane-2,2-diamine reacts with sulfur tetrafluoride in the presence of cesium fluoride at ambient temperature to give a mixture of l,2,2,2-tetrafluoro-l-(trifluoro-methyl)ethylamine (6) and 1-amino-2,2,2-trifluoro-l-(trifluoromethyl)ethyliminosulfur difluoride (7). The latter reacts further with sulfur tetrafluoride at 70"C to afford a mixture of 1,2,2,2-tetrafluoro-l-(trifluoromethyl)ethyliminosulfur difluoridc (8), 2,2,2-trifluoro-l-(trifluoro-methyl)ethylidenebis(iminosulfure) difluorid (9) and a dimeric compound 10. Compound 8 can also be formed in 70-83% yield from 6 or from 2,2,2-trifluoro-1-(trifluoromethyl)-ethylimine (II).200... 

Aromatic amines do not give iminosulfur difluorides in their reactions with sulfur tetrafluoride, but, instead, independent of the nature of the aromatic ring substituents, give the corresponding bis(phenylimino)sulfur 12 exclusively.170,201... 

Many organic and inorganic cyanides, cyanates, isocyanates and thiocyanates react with sulfur tetrafluoride at elevated temperatures with the formation of iminosulfur difluorides. Thus, cyanogen bromide, sodium cyanide, and sodium thiocyanate give (trifluoromethyl)imino-sulfur difluoride (1) in 37 -70% yield.202... 

Pentafluorocthyl)iminosulfur difluoride (2) is obtained in 70% yield from trifluoroacetonitrile and sulfur tetrafluoride at 350LC.202... 

Sulfonamides, like carboxamides, react at the amine side to form sulfonyliminosulfur difluorides. Thus, sulfamide reacts with sulfur tetrafluoride at ambient temperature in the presence of sodium fluoride as a hydrogen fluoride scavenger to give Af,AT-sulfonylbis(iminosulfur difluoride) (2)207 but at elevated temperatures (fluorosulfonyl)iminosulfur difluoride (3) is the main product.173 The latter is also formed from sulfamic acid173 and fluorosulfonamide.208... 

Fluoroalkyl)sulfanylamines,210 fluoro-Xsulfanylamines,211 and difluorophosphoramidic acids212 react with sulfur tetrafluoride under mild conditions to form the respective iminosulfur difluorides, e.g. 5-7. 

Thiadiazole oxides and reduced forms are readily prepared via [4+1] cyclizations (Table 17). The reagents employed for this purpose are thionyl chloride, sulfuryl chloride, sulfur tetrafluoride, V,lV -bis(p-toluenesulfonyl)sulfur diimide, cyclic diimides, pentafluoroethyl-iminosulfur difluoride and sulfamide. 

The reaction of sulfur chlorides (7, 64) and iminosulfur difluorides (64) with dialkali salts of perfluoropinacol is another synthetic route to 1,3,2-dioxathiolanes 133b-e. 

Iminosulfur difluorides, RN8F2, are isoelectronic with 8OF2. They are obtained by the reaction of 8F4 with cyanates,... 

Without additional reagents Iminosulfur difluorides from nitriles... 

Iminosulfur difluorides from isocyanates and from nitriles s. 16, 371 N tSFj... 

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