Sodium fluoride carbonyl difluoride

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... 

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 ... 

In the reaction of ethanol with COFj, the reaction is catalysed by pyridine [589]. Ethane-1,2-diol, however, is reported to react with an excess of COF at -80 C to give a 79% yield of the bis(fluoroformate) in the presence of sodium fluoride (which acts as a base to absorb the HF by-product) [24a]. No reaction occurs when carbonyl difluoride is passed into a solution of phenol in diethyl ether, and passage of COFj into a mixture of phenol, pyridine and benzene results in the production of a quantitative yield of diphenyl carbonate. Phenyl fluoroformate was prepared by heating a mixture of COF, PhOH and benzene at 100 "C, however, in an autoclave [589]. 

A higher (62%) yield of benzoyl fluoride was obtained from the reaction of benzoic acid and COFj in the presence of sodium fluoride, by beating the charged vessel at 175 "C for 10 h. The presence of the highly electronegative fluorine atom in benzoyl fluoride clearly deactivates the carbonyl group for further reaction with carbonyl difluoride. 

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