Abstract: Mono- and di-p-polyoxyethylene substituted triphenylphosphines(1) were prepared by the ethoxylation of diphenyl(4-hydroxyphenyl)phosphine and phenyldi(4-hydroxyphenyl)phosphine. RhCl₃/1 complexes have desirable catalytic properties in aqueous/organic biphasic hydroformylation of 1-hexene, with a conversion up to 95%, and can be reused for 5 times without loss in activity. Since ligands 1 possess inverse temperature-dependent solubility in water, the hydroformylation has undergone an interesting process of thermoregulated phase-transfer catalysis, in which the catalyst transfers into the organic phase to catalyze the reaction at a higher temperature, and returns to the aqueous phase to be separated from the product at a lower temperature after the reaction is completed.

Key words: Ethoxylation, Hydroformylation, Thermoregulated phase-transfer catalysis, Mono- and di-p-polyoxyethylene substituted triphenylphosphines