Compared to heterogeneous catalysis, homogeneous catalysis is characterized by higher selectivity and activity at milder reaction conditions, but, however, the separation of the expensive transition metal catalysts from the reaction products is difficult. Temperature-controlled solvent systems, which are present in two phases at low temperature and form a homogeneous, single-phase solvent system at higher temperature, disable mass transport limitations during the reaction. Upon cooling, a two-phase systemis formed again, of which in the ideal case one phase contains the product and the other the catalyst.