Fluorinated phosphorus compounds: Part 3. The synthesis of symmetrical and unsymmetrical fluoroalkyl phosphates

Treatment of phosphorus pentachloride with four molar equivalents of fluoroalcohol gave symmetrical phosphates (RFO)3PO in isolated yields between 10–92% [RFCF3CH2, C2F5CH2, HCF2CF2CH2, C3F7CH2, (FCH2)2CH, (CF3)2CH, C2F5(CH3)CH]. The reaction proceeded best for fluoroalcohols having many fluorine atoms. 2,2-Difluoroethanol HCF2CH2OH and 1,3-difluoroisopropanol (FCH2)2CHOH did not react cleanly and gave product mixtures. Hexafluoroisopropanol produced a 3:7 mixture of symmetrical phosphate [(CF3)2CHO]3PO and chlorophosphorane [(CF3)2CHO]4PCl. The latter reacted readily with water and alcohols. Heating the chloridates CF3CH2OP(O)Cl2, (CF3CH2O)2P(O)Cl and (C2F5CH2O)2P(O)Cl with various fluoroalcohols in the presence of calcium chloride catalyst gave unsymmetrical phosphates in isolated yields between 46–83%. The mixed phosphate (CF3CH2O)2P(O)OCH2C2F5 did not react with butanol or propylamine in dichloromethane at room temperature.