5-Nitrofuranyl Derivatives are Reactive Towards Methanolic Media as Exemplified by 1H, 13C NMR Spectroscopy & Their Colours

Most 5-nitrofuranyl derivatives, in particular, the frequently used 5-nitrofurfural building block in synthesis, are coloured compounds and their intrinsic colours can be a good indication of their purity by virtue of their specific extended π-delocalisation. To this end, the work herein reports a first-of-its-kind anhydrous synthesis of (E)-5- nitrofuran-2-yl methylene hydrazine, 5-nitrofuran-2-carbohydrazide, and its dimeric 5-nitro-N'-5-nitrofuran-2- carbonyl furan-2-carbohydrazide, alongside their intrinsic colours, and most importantly their reactivity towards several deuterated solvents together with their 1H and 13C NMR features in an attempt to unravel the basis of discrepancies in the appearance of purported (E)-5-nitrofuran-2-yl methylene hydrazine of high purity in the literature and that obtained herein.