Replacement sulfur tetrafluonde

Perfluoropmacol reacts with sulfur tetrafluonde in an unconventional way instead of replacement of the hydroxyl groups by fluorine, the substitution of four fluonne atoms in the sulfur tetrafluonde molecule with oxygen occurs to give the corresponding spirosulfurane [J6J] (equation 79)... 

The reaction of diethyl tartrate with sulfur tetrafluonde at 25 °C results in replacement of one hydroxyl group, whereas at 100 °C, both hydroxyl groups are replaced by fluonne to form a,a -difluorosuccinate [762] The stereochemical outcome of the fluonnation of tartrate esters is retention of configuration at one of the chiral carbon atoms and inversion of configuration at the second chiral center [163,164, 165] Thus, treatment ofdimethyl(+)-L-tartrate with sulfur tetrafluonde gives dimethyl meso-a,a difluorosuccinate as the final product [163, 164], whereas dimethyl meso tartrate is converted into a racemic mixture of D- and L-a,a -difluorosuccmates [765] (equation 80)... 

Highly fluorinated tertiary alcohols usually give olefins on fluonnation with sulfur tetrafluonde [759/, but in certain cases, replacement of the hydroxyl group with fluorine occurs under mild conditions Hexafluoro-2-arylpropan-2-ols react with sulfur tetrafluonde at low temperatures to give high yields of heptafluoro-lsopropylarenes [769] (equation 77), and similarly, 3,8 dihydroxy 9,9,9,10,10,10-hexafluoro-p-menthane affords 3,8,9,9,9,10,10,10-octafluoromenthane [769] (equation 78)... 

Esters of carboxylic acids are resistant toward sulfur tetrafluoride up to 300 °C. However, in the presence of an excess of hydrogen fluoride, they react like the acids to give trifluoromethyl compounds [187,235] In contrast, esters of highly fluorinated acids or alcohols react with sulfur tetrafluonde in a hydrogen fluoride solution under mild conditions without cleavage of the ester bond and give products of the replacement of carbonyl oxygen by fluorine a,a-difluoroethers [235, 236, 237, 238] (equations 124 and 125). 

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