Synthesis carbonyl difluoride

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). 

Carbonyl difluoride is not an esoteric material simple methods for its synthesis are well documented, and patents describing its economic preparation on a commercial scale are... 

Synthesis of carbonyl difluoride from carbon dioxide or carbonyl sulfide... 

Synthesis of carbonyl difluoride from phosgene 13.7.S.1 Reaction with difluorine... 

The reaction of phosgene with hydrogen fluoride offers a potentially attractive route to the synthesis of carbonyl difluoride. However, the hydrogen chloride co-product of the reaction, represented in Equation (13.4) has a boiling temperature (-83.1 C) very close to that of COFj (-84.6 "C). In addition, azeotrope formation occurs, so that the two materials are only separated with great difficulty using normal distillation techniques. Separation of the two materials may be affected using aliphatic nitriles (such as ethanenitrile) or aromatic hydrocarbons (such as toluene) in which HCl is more readily absorbed relative to COF j [629,630]. Alternatively, the separation may be affected by adsorption of the HCl onto a metal fluoride, SO 3 or PjOj, which do not react at all readily with the COFj [2069]. 

The oxidation of haiogenated methanes by SO 3 is particuiariy worthy of mention. By choice of the halogen substituents, each of the more common carbonyl dihalides, both symmetrical and asymmetrical, can be prepared by a convenient laboratory method. For the synthesis of carbonyl difluoride, the reagents CF Clj or CF Br may be used. The addition of CFjBtj (0.5 mol) to SO 3 (2.5 mol) at 35-44 C over 2 h resulted in a yield (based on CFjBrj) of COFj of 63 %, according to [1875] ... 

Carbonyl difluoride is a particularly versatile fluorinating agent, and an important material for the synthesis of organofluorine compounds [1079], Its reactions with perfluoroalkenes gives perfluoroacyl fluorides in the presence of a fluoride ion source, and its facile reaction with amines or alcohols results in the formation of carbamoyl fluorides or fluoroformates, respectively. The fluorination of carbonyl compounds, such as aldehydes and ketones, with COF can give gem-difluorides by replacement of the carbonyl oxygen atom with two atoms of fluorine e.g.-. 

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