Selective H–D exchange catalysed by aqueous phase and immobilised Pd nanoparticles

Pd nanoparticles (with a mean diameter of 3.4 ± 0.5 nm) prepared through BH4− reduction of Na2PdCl4 can catalyse selective H–D exchange (through reaction with D2O) at the carbon α to the N atom of a pyridine ring. Oxidised Pd(II) complex species also present as dissolved species in the nanoparticle dispersion play no part in the exchange. We have studied the effects of several different variables on the rate of the selective H–D exchange activity for a model pyridine, i.e. 4-dimethylaminopyridine (DMAP). These variables include temperature, nanoparticle aging, nanoparticle re-reduction with H2 and nanoparticle immobilisation onto multi-walled carbon nanotubes (MWCNTs). We have also extended the study to related pyridine containing molecules.