Hydrogen 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 formed electrochemically by introducing CO into the pores of a porous anode (porous carbon) of an electrolysis cell containing anhydrous hydrogen fluoride with a small quantity of a metal fluoride, such as KF, to provide adequate conductivity [368], Whilst the stoicheiometry corresponds to ... 

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]. 

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 ... 

CARBONYL DIFLUORIDE or CARBONYL FLUORIDE (353-50-4) CFjO Noncombustible gas. Reacts with water or steam, producing hydrogen fluoride gas and carbon dioxide. Violent reaction with strong oxidizers bases including amines, amides, and inorganic hydroxides alcohols and glycols dinitrogen tetraoxie, hexafluoroisopropylideneaminolithium ethers in the presence of metal salts. If flow... 

CARBONYL DIFLUORIDE (353-50-4) Reacts with water or steam, producing hydrogen fluoride gas and carbon dioxide. Violent reaction with strong oxidizers, dinitrogen tetraoxide. 

The high boiling point of trifluoro(phenyl)-/l4-sulfane (4) enables reactions to be performed at atmospheric pressure in normal glassware. It is important that all reactions are carried out under anhydrous conditions and contact with glass be kept to a maximum of several hours to avoid hydrolysis (caution hydrolysis will liberate hydrogen fluoride). It has been reported that trifluoro(phenyl)-24-sulfane can convert carbonyl compounds to gem-difluorides, e.g. 5-6. 

The addition to the C=N bond is limited to reactive species, such as hydrogen halides, carbonyl fluoride and organometallics, and seems to proceed well only with carbonimidoyl difluorides. The dehalogenation of carbonimidoyl dihalides by triphenylphosphine provides a useful method to generate isocyanides, which are sometimes difficult to obtain by Hofmann s classical method. 

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