Catalytic Epoxidation of 1-Octene with Diluted Hydrogen Peroxide: On the Basic Role of Hydroxo Complexes of Platinum(II) and Related Species

The basic behavior of P2Pt(Rx)(OH) complexes (P2= two tert-monophosphines or-diphosphine; Rx = activated alkyl or aryl) has been investigated in protic media with pH and conductivity measurements. More insight into the nature of the Pt-O bond in diphosphine complexes has been gained with the aid of 31P NMR from 1JP-PTdata. A wide class of cis and trans complexes of the above type has been tested as catalysts in the selective epoxidation of 1-octene with 35% H202. Only diphosphine derivatives were found active. The system has been investigated both in monophasic (THF and EtOH) and biphasic (CH2Cl2/H2O) media. The effect of cationic complexes and the dilution of H202 down to 5% are also reported. Evidence for the involvement of cationic platinum-olefin species in the catalytic cycle is reported, while the possible pathways with which oxygen transfer occurs are discussed in more detail, and a possible explanation is given for the unusual selectivity. © 1985, American Chemical Society. All rights reserved