Hydrolysis of Dimethyl Methylphosphonate (DMMP) in Hot Compressed Water

Dimethyl methylphosphonate (DMMP) is widely used as a chemical surrogate for G- and V-type nerve agents, exhibiting similar physiochemical properties, yet significantly lower toxicity. Continuous hydrolysis of DMMP in hot-compressed water is performed at temperatures from 200 to 300 °C, pressures of 20 and 30 MPa, and residence times from 30 to 80 s to evaluate the effects of pressure and temperature on reaction kinetics. DMMP hydrolysis is observed to follow pseudo-first-order reaction behavior, producing methylphosphonic acid and methanol as the only detectable reaction products. This is significant for the practical implementation of a continuous hydrothermal reactor for chemical warfare agent neutralization, as the process only yields stable, less-toxic compounds. Pressure has no discernible effect on the hydrolysis rate in compressed liquid water. Pseudo-first-order Arrhenius parameters are determined, with an activation energy of 90.17±5.68 kJ mol-1 and a pre-exponential factor of 107.51±0.58 s-1.