A study of the formation and application of new chiral water soluble lanthanoid benzoates using real-time infrared spectroscopy

Abstract

A range of water soluble lanthanoid benzoate complexes of composition [Ln(Bz)3(H2O)n] (Ln = La, Gd, Ho and Yb; Bz = 3,5-bis ((R)-2,3-dihydroxypropoxy) benzoate and 3,4,5-tris((R)-2,3-dihydroxypropoxy) benzoate) have been prepared by reaction of lanthanoid bicarbonates with three equivalents of the corresponding optically active benzoic acid in water. Application of [Ln(Bz)3(H2O)n] as asymmetric catalysts for epoxide ring opening reactions has been investigated using styrene oxide, showing complete conversion after 20 h, albeit with no significant enantiomeric excess observed. The formation of the lanthanoid complexes and subsequent catalytic conversion of styrene oxide to phenylethane-1,2-diol were monitored using real-time infrared (RTIR) spectroscopy, yielding information about reaction pathways and intermediates.