Hydroformylation of the post-metathesis product 7-tetradecene using rhodium(I) Schiff base derived precatalysts

Abstract

The rhodium-catalysed hydroformylation of the post-metathesis product 7-tetradecene using aryl- (1) and ferrocenyl- (2) Schiff base derived precatalyst complexes was investigated. It was found that the reaction temperature (75–115 °C), pressure (30–60 bar, CO/H2 = 0.5–2) and 7-tetradecene-to-precatalyst molar ratio (1000:1–6000:1) had a significant influence on the hydroformylation performance. Turnover numbers up to 4310 were observed and the selectivity data show a temperature and pressure-dependent conversion of 7-tetradecene to the primary branched aldehyde product 2-hexylnonanal and isomeric branched aldehydes. A cooperative effect between rhodium and ferrocene was observed as hydroformylation performance results obtained with the heterobimetallic precatalysts (2) differ from that achieved using the monometallic catalyst system (1) under mild reaction conditions. Both precatalysts performed optimally at a temperature of around 95 °C. Lifetime studies with the precatalysts were conducted and the precatalysts were found to remain active over at least three consecutive reaction cycles