Sulfur fluorides reaction with, carbonyl difluoride

Carbonyl difluoride reacts vigorously with water, to produce carbon dioxide and hydrogen fluoride [1756]. A similar reaction is observed with concentrated sulfuric acid, and it is completely absorbed by sodium hydroxide solution [1756]. Indeed, the reaction between COFj and D O at 0 C has been used to prepare DF in purities >99.5% and yields of 90% [1554], A recent ab initio study [677aa] of the mechanism and energetics of the gas-phase reaction of carbonyl difluoride with water indicates that the reaction proceeds through two transient intermediates - CFj(OH)j and FC(0)0H. The former dissociates to the latter and HF, and the FC(0)0H then dissociates into COj and HF, consistent with the overall stoicheiometry ... 

An example of cleavage ol the sulfur-oxygen bond in trifluoromethane-sulfonic ester has been reported Tnfluororaethyl triflate reacts with neutral or anionic nucleophiles with elimination of carbonyl difluoride and formation of trifluoromethanesulfonyl fluoride [57] (equation 32) The mechanism of this reaction involves elimination of fluoride ion, which is a chain carrier in the substitution of fluorine for the trifluoromethoxy group... 

Both aromatic and aliphatic fluoroformates 7 can be readily prepared from phenols or alcohols and carbonyl difluoride and treated with sulfur tetrafluoride without isolation. Hydrogen fluoride evolved in the reaction of hydroxy compounds with carbonyl di fluoride serves as a catalyst for the consecutive reaction with sulfur tetrafluoride.15<)-162 This provides a general, convenient, direct synthesis of aryl and alkyl trifluoromethyl ethers 5 from phenols and alcohols. When the intermediate fluoroformate 7 is isolated prior to treatment with sulfur tetrafluoride, at least one mole equivalent of hydrogen fluoride is necessary to promote the fluorination reaction. 159 163 Representative examples of the conversion of hydroxy compounds 6 into trifluoromethyl ethers 5 via intermediate fluoroformates 7 are given (for other examples 7 -> 5, see Houben-Weyl, Vol. E4, pp 628. 629). 

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... 

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