Ethyl fluoroformate

Diazoalkanes react with ethyl fluoroformate [S7j and acyl fluorides [87, 55] to give ethyl ot-fluorocarboxylates and ot-fluoroketones, respectively (equation 22) Table 7 lists examples of hydrofluorination [6. 83, 89] and geminal difluori-nation [90] of aryldiazomethanes... 

These findings were in accordance with expectation, and it was now obvious that the toxicity was bound up with the FCHjCO group, whereas the FCO group was ineffective. Farther confirmation of this point was provided by the observation that ethyl fluoroformate, FCOOEt, was non-toxic. Fluoro-aoetic anhydride was slightly more toxic (by inhalation) than methyl fluoroacetate. 

Goswami and Sarkar3 claimed to have prepared methyl and ethyl fluoroformates by the action of thallium fluoride on the corresponding chloroformates. These fluoroformates were described as powerful lacrimators. We found that no appreciable reaction took place between potassium fluoride and ethyl chloroformate in boiling carbon tetrachloride or nitrobenzene. Ethyl fluoroformate could, however, be readily produced by the action of potassium fluoride on ethyl chloroformate by using the autoclave technique. It was found not to have the lacrimatory properties claimed for it, and was non-toxic in comparison with M.F.A. This non-toxicity was to be expected, as the fluoroformate contains the COF and not the CH2F- group. 

Ethyl fluoroformate, obtained by the action of thallium fluoride on ethyl chloroformate, is a liquid with b.p. 57° C. and density i-ii at 33° C. 

Ethanol combines with COCIF at low temperature to give predominantly ethyl fluoroformate some diethyl carbonate is also produced. No base catalyst is required for the reaction [589] ... 

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