While the selectivity to linear and branched aliphatic oligomers declines with temperature, the formation of the non-aromatic cyclic trimer isophorone is not significantly affected. At 240 °C and above, the formation of mesitylene is favored and identified as the main product. Total product selectivity at 260 °C is 66 %, demonstrating that the reaction is effective even at elevated temperatures. No additional impact is observed when switching from liquid acetone to supercritical acetone above 235 °C. By varying the reaction temperature, a strong influence on the mesitylene activity is found with a maximum selectivity at 260 °C for Siralox 30. The following experiments were therefore carried out at 260 °C.