Electron Impact Ionization Mass Spectra of 3-Amino 5,6-dimethoxyl-2-methyl quinazolin-4-(3H)-one Derivative

  • Osarumwense Peter Osarodion
  • Edema Mary Orile
  • Usifoh Cyril Odianosen
Keywords: Mass spectroscopy, Synthesis, Quinazoline-4-one, 2-methyl 6, 7-disubtituted 1, 3-benzo-oxazine-4-one, Nucleophile, Electron Impact Ionization Mass Spectra


The synthesis of novel heterocyclic derivatives has attracted considerable attention. The explosive growth of heterocyclic chemistry is emphasized by the large number of research publications, monographs, and reviews. The heterocyclic organic compounds are extensively disseminated in natural and synthetic medicinal chemistry and are vital for human life.  Looking at the previous studies on quinazolinones derivatives, only limited information is available on their mass   spectral along with the preparation of novel quinazolin-4-(3H)-one derivatives. Objective of this study, was to synthesize a novel 2-Methyl-6, 7-dimethoxy-quinazolin-4-one was synthesized via the reaction between 2-Methyl-6, 7-dimethoxy-benzo-1,3-oxazin-4-one and hydrazine hydrate and study their electron impact (EI) mass spectral fragmentation. The condensation of 2-amino-methyl-4, 5-dimethoxybenzoate with acetic anhydride yielded the cyclic compound 2-methyl-4, 5-disubstituted-1, 3-benzo-oxazine-4-one which further produce a novel 2,3-disubstituted quinazolin-4 ones via the reaction with hydrazine hydrate. The compounds synthesized were unequivocally confirmed by means of Infrared, Nuclear Magnetic Resonance (1H and 13C), Gas Chromatography Mass Spectrophotometer and Elemental analysis. The molecular ion of m/z 235 fragment to give m/z 220 by loss of –NH group. The ion of m/z 220 was broken to give m/z 206 by losing CH2 group and fragment to m/z 177 by loss of HCO. This fragmented to m/z 162 by loss of –CH3 group and then m/z 136 by loss of CN group. The loss of O gave m/z 120 which fragment to give m/z 93 by loss of –HCN and finally gave m/z 65 by loss of CO group. The electron impact ionization mass spectra of compound 2 show a weak molecular ion peak and a base peak of m/z 235 resulting from a cleavage fragmentation. Compound 2 give a characteristic fragmentation pattern. From the study of the mass spectra of compound 2, it was found that the molecular ion had fragmented to the m/z 220. The final fragmentation led to ion of m/z 93 and ion of mass m/z 65, respectively.