Rates of Claisen rearrangement determined with a flow-type high-temperature and high-pressure NMR probe

Rate constants of Claisen rearrangement of allyl phenyl ether in subcritical water (272–306 °C) at 25.4 MPa were determined. The activation energy in this temperature range was evaluated to be 106 ± 5 kJ mol−1. To study the kinetics of reactions occurring in water at pressures up to 40 MPa and temperatures up to 400 °C, we developed a flow-through high-temperature and high-pressure NMR probe equipped with a mixing port above the RF detector. To suppress the large 1H signal of H2O, the binomial sequence pulse technique was applied.