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

Article abstract of DOI:10.1016/S0022-1139(00)00327-4

Treatment of phosphorus pentachloride with four molar equivalents of fluoroalcohol gave symmetrical phosphates (R_FO)₃P=O in isolated yields between 10-92% [R_F=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)OCH₂C ₂F₅ did not react with butanol or propylamine in dichloromethane at room temperature.