Next to the alkyl halide 1 , temperature, 2,3 pressure 4,5 , and the solvent, especially the polarity of the media has the most pronounced influence on the conduction of ATRP reactions. Several temperatures were used to investigate the influence on the CuCl/CuCl2-System (Table ). Starting from room temperature (23 °C) the temperature was varied to 40, 50, 60 (used before), 70, or 80 °C (Table and ).