Control of reversible reactions in supercritical water: I. alkylations

The reaction rates of alkylation of phenol and that of dealkylation of alkylphenol were evaluated in sub‐ and supercritical water. Dehydration of 2‐propanol gave propene, and then alkylation with phenol, which produced 2‐isopropylphenol. Then 2‐propylphenol was formed by rearrangement of 2‐isopropylphenol. The alkylation rate was higher than the dealkylation rate, as water density increased and temperature decreased at 613–713 K and 0.3–0.6 g/cm 3 of water density. At around 673 K, the order of magnitude of the alkylation and dealkylation rates reversed and become sensitive to the system temperature and density. These results demonstrate some of the specific features of supercritical water: the reaction rate of both forward and reverse reactions, such as alkylation and dealkylations, can be controlled through manipulation of temperature and density (pressure).