Fluonnated, preparation from

Instead of perchlorates, tnfluoromethanesulfonates (Inflates) can be used They are readily prepared and claimed to be safer than perchlorates [75] F Aryl fluondes have been prepared from p YC6H4N" (CH3)3CF3S03- (Y = COCqHs, CN, CHO, NO2, COCH3, CO2C2H5) by this alternative substrate Fluorodequaternization can also be applied to the preparation of fluonnated heterocyclics such as 4 fluoro 6 phenyl 1,3 pyrimidine [76] (equation 15) and fluoropunnes [77]... 

Fluorinated bicyclo[2 2 0]hex 5-en 2 ones prepared from Dewar benzene derivatives serve as synthons of cyclobutenes [269] Photochemical cleavage of fluonnated azacyclohexadiene in the gas phase also gives fluorinated cyclobutene [270] (equation 41)... 

When potassium fluoride is comhined with a variety of quaternary ammonium salts its reaction rate is accelerated and the overall yields of a variety of halogen displacements are improved [57, p 112ff]. Variables like catalyst type and moisture content of the alkali metal fluoride need to be optimized. In addition, the maximum yield is a function of two parallel reactions direct fluonnation and catalyst decomposition due to its low thermal stability in the presence of fluoride ion [55, 59, 60] One example is trimethylsilyl fluoride, which can be prepared from the chloride by using either 18-crown-6 (Procedure 3, p 192) or Aliquat 336 in wet chlorobenzene, as illustrated in equation 35 [67]. 

Mixtures of anhydrous hydrogen fluoride and tetrahydrofuran are successfully used as fluonnating agents to convert 1,1,2-trifluoro-l-alken-3-ols, easily prepared from bromotrifluoroethene via lithiation followed by the reaction with aldehydes or ketones, to 1,1, l,2-tetrafluoro-2-alkenes The yields are optimal with a 5 1 ratio of hydrogen fluoride to tetrahydrofuran The fluonnation reaction involves a fluoride ion-induced rearrangement (SN2 mechanism) of allylic alcohols [65] (equation 40)... 

A fluonnated dithiaparacyclophane is prepared from lithium sulfide and 1,4 bis(bromomethyl)tetrafluorobenzene [48] (equation 43)... 

Perfluorodimethyladamantane is prepared from adamantane dicarboxylic acid by treatment with sulfur tetrafluoride followed by energetic fluonnation with cobalt trifluoride over two temperature ranges [S] (equation 15)... 

Whereas access to fluoromethylene ylides is easy, higher homologues are more difficult to prepare because ot the facile (1-elimination of fluorine However hexafluoroisoprapylidene ylides may be prepared in situ from tetrakisftnfluoro-methyl)-l,3-dithietane and tnphenylphosphme [54 (equation 51) or 2,2-dichloro-hexafluoropropane and tnphenylphosphme [55, 56, 57 (equation 52) (Table 21) Pcrfluoro-2-buteiie reacts with tnbutylphosphine to cleanly form a solution of a fluonnated ylide [5/ ] (equation 53)... 

Fluoroolefins may he prepared by the reaction of Wittig reagents and other pho sphorus-containtng y tides with fluorinated carbonyl compounds. (A discussion of the fluorinated Wittig reagents or other fluonnated phosphorus reagents with nonfluorinated carbonyl compounds is on page 581.) Tnphenylphosphoranes, derived from alkyltriphenyl phosphonium salts, react with 1,1,1-trifluoroacetone [3/] or other trifluoromethyl ketones [32, iJ] (equation 26) (Table 10). 

The preparation of fluonnated acid anhydrides can be done by simple methods Phosphorus pentoxide removes a molecular equivalent of water from tnfluoroacetic acid and tnfluoromethanesulfonic acid and forms the mixed anhydride [Si] (equation 53)... 

Examples of modem fluonne-contaimng herbicides, insecticides, and fungicides are shown below Most of these compounds are prepared starting from fluonnated bulk chemicals, such as fluonnated carbocyclic and heterocychc compounds, benzotnfluonde, fluonnated acetic acid denvatives, and Freons Direct fluonnation is used only occasionally by producers of fme chemicals and wiU, at least in the near future, remain the domam of producers of bu Ik chemicals who have the necessary techmcal expertise Fungicides... 

For most cases, common fluoroacyl derivatives are sufficiently reactive and selective Thus conversion of perfluoroglutaric dichloride to a monomethyl ester by methanol proceeds smoothly under the appropriate reaction conditions [17] (equation 9) Perfluorosuccinic acid monoester fluoride, on the other hand, is prepared most conveniently from perfluorobutyrolacetone [IS] (equation 10) Owing to the strong acidity of a fluonnated carboxylic acids, Fischer esterification with most aliphatic alcohols proceeds autocatalytically [79 20]... 

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