Additions of PH₃ to Monosubstituted Alkenes of the Formula H₂CCH(CH₂)<i>_x</i>(CF₂)<i>_y</i>CF₃: Convenient, Multigram Syntheses of a Family of Partially Fluorinated Trialkylphosphines with Modulated Electronic Properties and Fluorous Phase Affinities

Abstract

Reactions of PH(3) and commercially available H(2)C=CHR(f) (R(f6)(/)(8)(/)(10) = (CF(2))(5)CF(3)/(CF(2))(7)CF(3)/(CF(2))(9)CF(3)) give, in two-stage processes conducted with free radical initiators (AIBN, VAZO; 80-90 degrees C), the phosphines P(CH(2)CH(2)R(f))(3) (1-3; 63-75%). Analogous reactions with H(2)C=CHCH(2)R(f8) (7) and H(2)C=CHCH(2)CH(2)R(f8) (10) give P(CH(2)CH(2)CH(2)R(f8))(3) (4, 73%) and P(CH(2)CH(2)CH(2)CH(2)R(f8))(3) (5, 66%), in which the phosphorus is increasingly insulated from the electronegative R(f) moiety. The alkenes 7 and 10 are prepared from Bu(3)SnCH(2)CH=CH(2) and IR(f8) (hnu, CH(2)Cl(2), 81%) or ICH(2)R(f8) (VAZO, refluxing CF(3)C(6)H(5), 56%). The reaction of 1 and H(2)O(2) gives O=P(CH(2)CH(2)R(f6))(3) (6, 88%), which can be reduced with HSiCl(3) to 1. Partition coefficients (CF(3)C(6)F(11)/toluene, 27 degrees C) range from 98.8:1.2 (1, 4) through 98.9:1.1 (5) to >99.7:<0.3 (2, 3, 6). Crystals of 4 diffract poorly, but a packing motif that maximizes interactions between R(f) segments is evident.