Synthesis and structural study of Nʹ-acetyl-N-(2,4-dinitrophenyl)hydrazine

Nʹ-acetyl-N-(2,4-dinitrophenyl)hydrazine 2 was obtained by the action of glacial acetic acid on 2,4-dinitrophenylhydrazine upon heating without catalysts (for example, concentrated sulfuric acid, suggested previously) and as the main reaction product, not the minor one, as was known in the literature. Its structure was studied in detail by various physicochemical methods (IR, 1H, 13C NMR, gas chromatography– mass spectrometry and X-ray structural analysis) in comparison with the information available in the literature. The IR, 1H, and 13C NMR spectra are in good agreement with the published data, the gas chromatography– mass spectrometry results are supplemented by the proposed fragmentation scheme. The supramolecular structure of compound 2 was studied for the first time in comparison with similar compounds, namely, with the X-ray analysis data of Nʹ-acetyl-N-(2,4-dinitrophenyl)hydrazine hydrate 2∙H2O, N'-(2,4- dinitrophenyl)formylhydrazide 3, N'-(2,4-dinitrophenyl)benzohydrazide 4, and N'-(2,4-dinitrophenyl)-2- fluorobenzohydrazide 5. For all five compounds, the molecular conformation is determined by the intramolecular N–H…O hydrogen bond, which is stronger in the case of compound 2 and its hydrate (dN–H…O 1.95 Å) compared to hydrazides 3–5 (dN–H…O in the range of 2.01(7)–2.02(9) Å). Formation of molecular packing in all crystals is due to intermolecular hydrogen bonds of the N H…O type. For structure 2, indicated in the title, it has also been noted that it is one of the few examples of compounds with intermolecular ONO…NO2, NO2…π interactions in a crystal.