Decomposition of phosphonofluoridates on glass

Neat droplets of O,O-diisopropylphosphorofluoridate (DFP) and O-1,2,2-trimethylpropyl methylphosphonofluoridate (Soman) decompose on glass. In thirty hours at room temperature over 40% of the Soman has been decomposed while nearly 15% of the DFP has been degraded. NMR spectroscopic analysis of the Soman showed that Soman decomposed exclusively by scission of the PF bond to form O-1,2,2-trimethylpropyl methylphosphonic acid. The rate of decomposition of the two organophosphorus fluorine substrates is proportional to the rate of hydrolysis. The results are consistent with earlier studies which showed that silica or magnesia promoted the decomposition of sarin (O-2-propylisopropyl methylphosphonofluoridate). The rate of decomposition on glass is accelerated in the presence of high humidity.