1,1-Dimethyl-1-( 2-hydroxypropyl) amine p-substituted benzimide ("aminimide") derivatives were prepared by the reaction of p-substituted methyl benzoates with equimolar amounts of 1,1-dimethylhydrazine and propylene oxide. These ylide compounds are shown to be useful as thermally latent initiators for the polymerization of glycidyl phenyl ether (GPE). Bulk polymerization of GPE with 3 mol % of these aminimides was carried out at 40-150 degrees C for 8 h, showing greater than or equal to 100 degrees C was required for an effective rate. No consumption of the monomer could be observed at temperatures lower than 80 degrees C. p-Methoxy substituted 1 showed the :Largest thermal latency among four aminimides tested. The activities of the aminimides increased with an increase of electron-donating ability of the substituents on the benzene ring, according to the following order : 1(p-MeO) > 2(p-Me) > 3(H) > 4(p-NO2).