Phase Transfer Activation of Fluorous Analogs of Grubbs’ Second Generation Catalyst: Ring Opening Metathesis Polymerization

Robert Tuba, Rosenildo Da Costa, Hassan S. Bazzi, John A. Gladysz

Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

Crynodeb

Grubbs’ second-generation alkene metathesis catalyst and the fluorous analog (H2IMes)((Rf8(CH2)2)3P)(Cl)2Ru(═CHPh) (1; H2IMes/Rf8 = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene/(CF2)7CF3) catalyze ring-opening metathesis polymerizations of norbornene at essentially identical rates (CDCl3, RT). However, dramatic accelerations can be observed with 1 in the presence of the fluorous solvent perfluoro(methylcyclohexane) (PFMC). The fluorous phosphine (Rf8(CH2)2)3P must first dissociate from 1 to generate the 14-valence-electron intermediate that begins the catalytic cycle and should be scavenged by the PFMC phase (PFMC/toluene partition coefficient >99.7:<0.3). This would allow alkenes to more effectively compete for active catalyst. However, faster rates are seen only when 1 (partition coefficient 39.6:60.4) is added as a PFMC solution or a PFMC/CDCl3 biphase mixture, as opposed to CDCl3 solution, and possible additional contributing factors are analyzed. Analogous effects are observed with a 7-oxanorbornene-based N-butylsuccinimide. The molecular weights, polydispersities, glass transition temperatures, and cis/trans C═C linkage ratios of the polynorbornene produced under monophasic and biphasic conditions are compared and are usually similar.
Iaith wreiddiolSaesneg
Tudalennau (o-i)155–162
CyfnodolynACS Catalysis
Cyfrol2
Rhif cyhoeddi1
Dynodwyr Gwrthrych Digidol (DOIs)
StatwsCyhoeddwyd - 29 Tach 2011

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