Thermoregulated Biphasic Catalysis

Thermoregulated Phase Transfer Catalysis - A conceptual advance in the field of biphasic hydroformylation of higher olefins is the use of rhodium catalysts generated from nonionic tenside phosphines, such as ethoxylated tris(4-... 

Because of their low solubilities in the aqueous phase, the hydroformylation of higher alkenes (>C2) is still a challenging problem. In addition to fluorous biphasic catalysis, possible solutions, which have been addressed, include the addition of surfactants240,241 or the use of amphiphilic ligands242-244 to enhance mutual solubility or mobility of the components across the phase boundary and thereby increase the rate of reaction. The use of polar solvents such as alcohols,245 p-cyclodextrin,246 cyclodextrin ligands,247 248 thermoregulated phase-transfer... 

Recently, a new aqueous biphasic catalytic system based on the cloud point of nonionic tensioactive phosphine, termed thermoregulated phase-transfer catalysis (TRPTC) has been developed [13]. The concept ofTRPTC as a missing link could not only provide a meaningful solution to the problem of catalyst/product separation, but also extricate itself from the limitation of low reaction rates of water-immiscible substrates. 

Thermoregulated phase-transfer catalysis has been used successfully for the aqueous biphasic hydroformylation of higher olefins [13, 18]. A reasonable explanation for the satisfactory catalytic reactivity is that it results from the thermoregulated properties of Rh/TRL complexes. As shown in Table 1, average turnover frequencies (TOFs) of250 h for 1-dodecene and 470 h for styrene have been achieved. Even the hydroformylation of oleyl alcohol, an extremely hydrophobic internal olefin, exhibits a yield of 72% [24]. 

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