In situ PHIP NMR - a new tool to investigate hydrogenation mediated by colloidal catalysts

It is known that some colloidal catalysts show "homogeneous"-like behavior, but it is unclear which parameters define the borderline between heterogen eous, i.e. surface reactions, and homogeneous-type catalysis of colloidal s ystems. The reaction of ethynylbenzene (phenylacetylene) with parahydrogen using the colloidal palladium catalyst Pd-x[(N(octyl)(4)Cl](y) leads to nuc lear spin polarization in the hydrogenation products. Accordingly, the in s itu NMR method parahydrogen induced polarization (PHIP) is an appropriate t ool to investigate hydrogenation mediated by colloidal catalysts. (C) 2001 Elsevier Science B.V. All rights reserved.