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

abstract

  • The fluorous tertiary phosphine [Rf6-(CH2) 2]3P [Rfn = CF3(CF2) n-1] and excess PhCH2Br, CH3(CH 2)3OSO2CF3, or R f6(CH2)2OSO2CF3 react (CF3C6H5, 45-110C) to give the phosphonium salts (PhCH2)[Rf6(CH2) 2]3P+ Br- (2, 71%), [CH 3(CH2)3] [Rf6(CH2) 2]3P+ CF3SO3- (3, 65%), or [Rf6-(CH2)2]4P + CF3SO3- (4, 83%). The phosphines [Rf6-(CH2)2]2[Rf8(CH 2)2]P and [Rf8(CH2) 2]3P are similarly elaborated with Rf6(CH 2)2I, Rf8(CH2)2I, or Rf8-(CH2)2Br (DMF, 115C) to [R f8(CH2)2]4-x[Rf6-(CH 2)2]xP+ I- (x = 3, 7; 2, 8; 1, 9; O, 10) or [Rf8-(CH2)2] 4P+ Br- (80-60%). The salts exhibit melting points between UOC and 43C, with lower values favored by less symmetrical cations, Rf6 segments, and triflate and bromide anions. Solubilities decrease in the solvent sequence CF3C6F 5 (all salts at least moderately soluble, room temperature) > acetone > THF > CF3C6H5 > CF 3C6F11 > CH3C6H 5, Et2O, CH2Cl2, 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 CF3C6F5 (97-86% for 2, 4, 9, 10) or CF 3C6H5 (85-66% for 2-4), demonstrating their potential for phase transfer catalysis. A CF3C6F 5 solution of Rf8(CH2)3I and aqueous NaCl react at 100C in the presence (but not the absence) of 9 to give Rf8(CH2)3Cl. 2006 Wiley-VCH Verlag GmbH & Co. KGaA.

published proceedings

  • Advanced Synthesis & Catalysis

altmetric score

  • 6

author list (cited authors)

  • Emnet, C., Weber, K. M., Vidal, J. A., Consorti, C. S., Stuart, A. M., & Gladysz, J. A.

citation count

  • 52

complete list of authors

  • Emnet, Charlotte||Weber, Kathleen M||Vidal, José A||Consorti, Crestina S||Stuart, Alison M||Gladysz, JA

publication date

  • August 2006

publisher