Hydroformylation of Methyl Methacrylate Catalyzed by Homogeneous and Polymer-Attached Rhodium Complexes

Article abstract of DOI:10.1021/jo01292a027

The hydroformylation of methyl methacrylate has been studied in the presence of RhH(CO)(PPh3)3 or its polymer-anchored analogue as the catalyst.The branched/normal product ratio was exceptionally sensitive to conditions, increasing as (1)

/ increased, (2) the pressure increased, (3) PPh3 was replaced by Ph2P(CH2)2P(Ph)(CH2)2PPh2, and (4) the polymer-supported phosphines replaced PPh3 at equivalent P/Rh ratios.The branched/normal selectivity decreased as (1)

/ increased and (2) the temperature increased.Changing the solvent from benzene to THF or adding Et3N had only minor effects on selectivity.The results are interpreted in terms of Wilkinson's mechanism where electronic effects control double-bond insertion into the rhodium-hydride bonds but isomerization equilibria of alkyl or acyl intermediates become more important at higher temperatures.