The synthesis and reactions of dialkyl fluoroalkyl phosphates

Dimethyl and diethyl fluoroalkyl phosphates were prepared from (1) a dialky l phosphite with a fluoroalcohol, triethylamine and carbon tetrachloride, ( 2) a dialkyl chlorophosphate with a fluoroalcohol and triethylamine, and (3 ) a dialkyl chlorophosphate with the sodium salt of a fluoroalcohol. Dimeth yl and diethyl (2,2,2-trifluoroethyl) phosphates reacted with bromotrimethy lsilane (TMSBr) in chloroform to give two products with loss of alkyl bromi de. The major product was an alkyl (trifluoroethyl) trimethylsilyl phosphat e, RO(TMSO)P(O)OCH2CF3 and the minor product was a bis(trimethylsilyl) trif luoroethyl phosphate, (TMSO)(2)P(O)OCH2CF3. The mechanism presumably involv es initial attack of an alkoxy oxygen atom on the silicon atom of bromotrim ethylsilane. Diethyl (2,2,2-trifluoroethyl) phosphate is resistant to chlor ination. It did not react with oxalyl or thionyl chloride in chloroform und er prolonged reflux. Unlike triethyl phosphate, it did not react with phosp horus oxychloride in chloroform under reflux. (C) 1999 Elsevier Science S.A . All rights reserved.