Sergei Zinovyev

Modifier effects on Pt/C, Pd/C, and Raney-Ni catalysts in multiphase catalytic hydrogenation systems

Abstract In the presence of a catalyst modifier (an onium salt, an amine, or a polyethylene glycol (PEG)), in a biphasic aqueous–organic mixture, the activity and the selectivity of hydrogenation reactions conducted using catalysts such as Pt/C, Pd/C or Raney-Ni, can change significantly. Hydrodehalogenation of haloaromatics, reduction of functional groups on the aromatic ring and of the aromatic ring itself, benzyl group hydrogenolysis, can be conducted under mild conditions, with high rates and interesting regio-, chemo- or stereoselectivities. The modifier coats the catalyst, thereby forming an interfacial film, wherein the reactions take place. This film partitions the catalyst at the aqueous–organic interface and influences the outcome of the reactions by mediating the substrate–catalyst interactions.

A comparative kinetic study of nucleophilic substitution under PTC conditions in liquid-liquid and solid-liquid systems

Abstract The phenomenon of initial exponential burst (IB) on kinetic curves in the reaction with solid salts was observed in the study on the SN2 substitution reaction of 2-octylmesylate with potassium halides under phase-transfer catalysis (PTC) conditions in liquid-liquid (l/l) and solid-liquid (s/l) systems. The mechanistic scheme describing the IB phenomenon in application to s/l PTC has been developed from the analysis of IB kinetic model known in enzyme kinetics.