Kinetics of Deuterium Exchange on Resorcinol in D2O at High Pressure and High Temperature

Abstract

The kinetics of deuteration of resorcinol in pure D2O were studied for the first time using a flow-through capillary tubular reactor with on-line, proton, and deuterium NMR detection at high temperatures and high pressure. The global rate constants for hydrogen/deuterium (H/D) exchange were determined from temperatures of 200−450 °C (723 K) at a pressure of ∼400 bar (the critical temperature and pressure of water are 374.2 °C and 218.3 bar, respectively). The H/D exchange rate in resorcinol (1,3-dihydroxybenzene) under these extreme conditions was determined using proton NMR as a function of the resorcinol residence time in a capillary tubular reactor, which also served as a high-pressure NMR cell. The 1H and 2H NMR results indicate that H/D exchange in resorcinol for the ring protons was observed at temperatures as low as 200 °C. The kinetics of H/D exchange in resorcinol and the activation energy was extracted from the experimental 1H NMR data.