Thermoregulated Phase-transfer Catalysis with Nonionic Water-soluble Phosphines

Thermoregulated Phase-transfer Catalysis with Nonionic Water-soluble Phosphines 

Several papers involving the synthesis of polyether-bound phosphines have been published previously. Okano et al. prepared tertiary phosphines 7 and 8 by Grignard reactions [14], and Harris et al. synthesized high-molecular-weight phosphines 9 and 10 through the functionalization of polyethylene glycols) (PEGs) 

N = average no. of ethylene oxide units per molecule of ligand. b N = n + m. 

Fig-1 General principle of thermoregulated phase-transfer catalysis. The mobile catalyst transfers between the aqueous phase and the organic phase in response to temperature changes. 

The analogous phenomenon was first reported by Bergbreiter etal. [17, 18]. In the presence of phosphorus-bonded block copolymers of ethylene oxide and propylene oxide as ligands ( smart ligands ), rhodium-catalyzed hydrogenation of maleic acid or allyl alcohol in the aqueous phase would show the same anti-Arrhenius reactivity. 

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