Temperature-Dependent or Thermomorphic Solvent Systems TMS

The general principle of temperature-dependent multicomponent solvent systems (thermomorphic solvent system (TMS)) is to conduct the hydroformylation 

The precondition is that solvent si is polar and almost immiscible with the nonpolar solvent s2. Solvent s3 is characterized by a semipolar nature and serves as the extracting agent. The miscibility gap is dependent on the properties of the participating solvents and the temperature. Commonly, solvent si dissolves the catalyst and solvent s2 extracts the products. Typical solvent mixtures are ATjAf-dimethylformamide (DMF)/Af,Af -dimethyl propylene urea/ -decane, DMF/NMP/ -decane, and propylene carbonate/n-dodecane/ethyl lactate. 

Meanwhile, networks of dominating reactions have been analyzed and models exist, vahdated by experiments, suggesting the optimal reactions conditions [115]. Usually, common Rh catalysts with phosphites as ligands are used. Recently, also rhodium nanoparticles have been successfully submitted to the reaction [116]. 

Clearly, the results are dependent on the catalyst used. Yangetal. [121] reported for the same substrate l/b ratios of 1 1 in the solvent system polyethylene glycol 400/1,4-dioxane/n-heptane with a Rh complex based on the monodentate ligand P[0CH2(CH20) CH3]3 (n = 8). But this system also was found to be rather robust. Even after recycling 23 times, no appreciable loss of catalyst activity was noted. Aldehyde yields reached up to 96%. Moreover, the average Rh loss was 0.65%. 

---