Phase equilibrium-driven selective hydrogenation of limonene in high-pressure carbon dioxide

Pressure-tuning of selectivity in the hydrogenation of limonene in carbon dioxide was found in biphasic systems, close but below the critical conditions of the reaction mixture, where hydrogen solubility in the liquid is highly dependent on pressure. The subtle effects of pressure on the two-phase region in CO2 + H-2 + a liquid reagent mixtures are essential factors in determining hydrogenation rates and selectivities in high-pressure carbon dioxide.