The synthesis and reactions of dialkyl fluoroalkyl phosphates

Abstract

Dimethyl and diethyl fluoroalkyl phosphates were prepared from (1) a dialkyl 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. Dimethyl and diethyl (2,2,2-trifluoroethyl) phosphates reacted with bromotrimethylsilane (TMSBr) in chloroform to give two products with loss of alkyl bromide. The major product was an alkyl (trifluoroethyl) trimethylsilyl phosphate, RO(TMSO)P(O)OCH 2CF 3 and the minor product was a bis(trimethylsilyl) trifluoroethyl phosphate, (TMSO) 2P(O)OCH 2CF 3. The mechanism presumably involves initial attack of an alkoxy oxygen atom on the silicon atom of bromotrimethylsilane. Diethyl (2,2,2-trifluoroethyl) phosphate is resistant to chlorination. It did not react with oxalyl or thionyl chloride in chloroform under prolonged reflux. Unlike triethyl phosphate, it did not react with phosphorus oxychloride in chloroform under reflux.