Mass spectrometric fragmentation of unsymmetrically substituted methylphosphonate diesters

A series of structurally related unsymmetrically substituted methylphosphon ate diesters have been synthesised and subjected to electron impact (EI) ma ss spectral studies. These studies though aimed at total identification of the compounds, resulted in certain interesting observations and hence are b eing reported. In order to confirm the observations under electron impact a nd to support the Mechanism of fragmentation we have also performed MS/MS e xperiments in both daughter ion and parent ion modes.