Syntheses and Properties of Fluorous Quaternary Phosphonium Salts that Bear Four Ponytails; New Candidates for Phase Transfer Catalysts and Ionic Liquids

The fluorous tertiary phosphine [R f6 (CH 2 ) 2 ] 3 P [R f n =CF 3 (CF 2 ) n −1 ] and excess PhCH 2 Br, CH 3 (CH 2 ) 3 OSO 2 CF 3 , or R f6 (CH 2 ) 2 OSO 2 CF 3 react (CF 3 C 6 H 5 , 45–110 °C) to give the phosphonium salts (PhCH 2 )[R f6 (CH 2 ) 2 ] 3 P + Br − ( 2 , 71 %), [CH 3 (CH 2 ) 3 ][R f6 (CH 2 ) 2 ] 3 P + CF 3 SO 3 − ( 3 , 65 %), or [R f6 (CH 2 ) 2 ] 4 P + CF 3 SO 3 − ( 4 , 83 %). The phosphines [R f6 (CH 2 ) 2 ] 2 [R f8 (CH 2 ) 2 ]P and [R f8 (CH 2 ) 2 ] 3 P are similarly elaborated with R f6 (CH 2 ) 2 I, R f8 (CH 2 ) 2 I, or R f8 (CH 2 ) 2 Br (DMF, 115 °C) to [R f8 (CH 2 ) 2 ] 4‐ x [R f6 (CH 2 ) 2 ] x P + I − ( x =3, 7 ; 2, 8 ; 1, 9 ; 0, 10 ) or [R f8 (CH 2 ) 2 ] 4 P + Br − (80–60 %). The salts exhibit melting points between 110 °C and 43 °C, with lower values favored by less symmetrical cations, R f6 segments, and triflate and bromide anions. Solubilities decrease in the solvent sequence CF 3 C 6 F 5 (all salts at least moderately soluble, room temperature)>acetone>THF>CF 3 C 6 H 5 >CF 3 C 6 F 11 >CH 3 C 6 H 5 , Et 2 O, CH 2 Cl 2 , hexane (all salts insoluble at elevated temperatures); some appreciably increase upon heating. Partition coefficients are very biased towards fluorous phases (>93:<7). The salts can be quite efficient at extracting picrate from water into CF 3 C 6 F 5 (97–86 % for 2 , 4 , 9 , 10 ) or CF 3 C 6 H 5 (85–66 % for 2 ‐ 4 ), demonstrating their potential for phase transfer catalysis. A CF 3 C 6 F 5 solution of R f8 (CH 2 ) 3 I and aqueous NaCl react at 100 °C in the presence (but not the absence) of 9 to give R f8 (CH 2 ) 3 Cl.