SO2 oxidation in aqueous solutions of Cu(II)

The Rh4(CO)12-Catalyzed Hydroformylation of 3,3-Dimethylbut-1-ene Promoted with HMn(CO)5. Bimetallic Catalytic Binuclear Elimination as an Origin for Synergism in Homogeneous Catalysis

“…51 This becomes accelerated as the concentration of substrate declines. Although the omnipresence of Rh 6 (CO) 16 during active hydroformylations has been repeatedly observed by this group, its decline as a function of time during Rh 4 (CO) 12 -initiated syntheses is unusual. The present mixed Rh-Mn hydroformylation (i.e., Figure 3) exhibits a steady decline in Rh 6 (CO) 16 despite declining substrate concentrations.…”

“…38 Hydroformylation of 3,3-dimethylbut-1-ene in the presence of tetrarhodium dodecacarbonyl alone has been extensively studied at low temperatures. 36 Detailed in-situ FTIR spectroscopic studies have shown the presence of only four observable organometallics, namely, the known species RCORh(CO) 4 , 39 Rh 2 (CO) 8 , 40 Rh 4 (CO) 12 , 41 and Rh 6 (CO) 16 , 42 where the latter normally exists at the ppm or sub-ppm level under most catalytic conditions. No evidence for observable quantities of the known rhodium hydride species 33,43,44 could be obtained in the presence of the very reactive organic reagent 3,3-dimethylbut-1-ene.…”

“…Loss of catalytic activity as a function of reaction time is frequently observed in homogeneous catalysis, and the unmodified rhodium-catalyzed hydroformylation reaction is no exception. The typical mechanism for deactivation is clusterification to the more thermodynamically stable Rh 6 (CO) 16 . 51 This becomes accelerated as the concentration of substrate declines.…”

“…The bimetallic catalytic binuclear elimination reaction would constitute a well-defined reaction topological basis for synergism. 16 The most convincing evidence to date for such a phenomenolgical basis for catalytic synergism appears to come from the Russian group of Beletskaya. They were able to show that lanthanum hydrides react in a stoichiometric manner with acyl cobalt tetracarbonyls to give aldehyde.…”

Kinetic models of multi-route reactions in homogeneous catalysis with metal complexes (A Review)

“…Systems such as PdCl 2 -CuCl 2 (used for the oxidation of CO [51] and olefins [52,53]) have provided a basis for several commercial processes (in particular, Wacker process). Several vari ants of classification were proposed for MCSs and PFCSs (see, e.g., [43,[54][55][56][57][58][59][60][61]. In recent years, systems with several catalysts have been also actively used in the synthetic organic chemistry (see Section 6), including the so called "tandem catalysis" [62] and systems combining metal complexes with acid-base [63] or organic [64] catalysts.…”