Potassium fluoride in diethylene glycol

Chloromethyl)oxirane (3) affords 1,3-difluoro- and l-chloro-3-fluoropropan-2-ol (4 and 5) on reaction with potassium hydrogen fluoride in diethylene glycol.76 There is no reaction when potassium fluoride is used which indicates that the epoxy ring in 3 is opened by the hydrogen fluoride present in potassium hydrogen fluoride and later the chlorine is exchanged for fluorine. 

A unique method for the introduction of fluorine via an ester-type linkage has been used for the preparation of fluorinated nucleosides.60 It consists of the treatment of 2,3 -anhydro nucleosides with hydrogen fluoride in the presence of aluminum trifluoride in dioxane at temperatures between 150 and 200 C.61,62 The yields are in the range of 30-40%. With potassium hydrogen fluoride in diethylene glycol as fluorinating agent, yields arc even lower.61 A more recent application of this method is the synthesis of 3.62... 

Preparation by heating a mixture of 3-acetoxy-4-melhoxy-a-bromoacetophenone and potassium hydrogen fluoride in diethylene glycol for 8 h at 100° (61%) [4686,4687]. 

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