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Rhodium catalysts modified with triphenylphosphine, triphenyl phosphite, and tris2,4ditertbutylphenyl phosphite have been evaluated for their performance in the hydroformylation of 1octene using carbon dioxide as the solvent. It is demonstrated that these catalysts are very efficient for the hydroformylation in carbon dioxide, although they are not designed for use in this medium. In particular, the catalyst prepared in situfrom dicarbonyl2,4pentanedionerhodiumI and tris2,4ditertbutylphenyl phosphite gave rise to an initial turnover frequency in excess of 3×104molaldehydemolRh h−1. Such a reaction rate is unprecedented for hydroformylation in supercritical carbon dioxiderich reaction mixtures.

Summary:For the application of catalytic chain transfer in (mini)emulsion polymerization, catalyst partitioning and deactivation are key parameters that govern the actual catalyst concentration at the locus of polymerization and consequently the final molecular weight distribution. A global model, based on the Mayo equation, catalyst partitioning and deactivation was developed. The influence of several reaction parameters on the instantaneous number average molecular weight was quantified.

A strong viscosity increase upon polymerization hinders radical formation during an ultrasound‐induced bulk polymerization. Since CO2acts as a strong anti‐solvent for most polymers, it can be used to reduce the viscosity of the reaction mixture. In this work, a process for the ultrasound‐induced polymerization in CO2‐expanded fluids has been developed. Temperature oscillation calorimetry has been applied to study the influence of CO2on the viscosity during the ultrasound‐induced polymerization. In contrast to polymerizations in bulk, the results show that a low viscosity is maintained during polymerization reactions in CO2‐expanded methyl methacrylate (MMA). As a consequence, a constant or even increasing polymerization rate is observed when pressurized CO2is applied. Moreover, the ultrasound‐induced polymer scission in CO2‐expanded MMA is demonstrated, which appears to be a highly controlled process. Finally, a preliminary sustainable process design is presented for the production of 10 kg/hour pure PMMA (specialty product) in CO2‐expanded MMA by ultrasound‐induced initiation.