Investigation of malonanilide and its dinitro-isomers using thermal analyses, mass spectrometry and semi-empirical MO calculation

ABSTRACT

In this paper malonanilide compound [M 1], and its dinitro-isomers [M 2 - M 4] compounds were investigated. The evaluation has been performed using thermal analyses [TA] measurements in comparison with electron ionization [EI] mass spectral [MS] fragmentation. Knowledge gained from experimental work was combined with theoretical calculations for neutral molecules, using the Modified Neglect of Diatomic Overlap [MNDO] semi-empirical MO calculations. The theoretical calculations include molecular geometry, bond order, charge distribution and heats of formation. For all the studied compounds, the major fragmentation pathways in TA and MS [including intermediates] is a CO-CH 2 bond rupture, followed by ketene [COCH 2] loss to form the nitroaniline structure. The MNDO procedure provides a basis for fine distinction among sites of initial bond cleavage, which is crucial to the rationalization of subsequent fragmentation of the molecule. Also, the thermal behavior decomposition due to ortho effect for o,o-dinitromalonanilide is discussed in terms of experimental and the MO calculations