Academic literature on the topic 'Nitrating mixture'

Two new energetic nitroaromatic compounds, 1,4-bis(1H-pyrazol-4'-yl)-2,5-dinitrobenzene (H2dpzb(NO2)2) and 1,4-bis(1H-3',5'-dinitropyrazol-4'-yl)-2,5-dinitrobenzene (H2dpzb(NO2)6), were prepared by nitration of 1,4-bis(1H-pyrazol-4'-yl)benzene (H2dpzb) with mixed acid. H2dpzb(NO2)x were isolated as yellow powders in moderate yields. They are stable under ambient conditions, soluble in dimethylformamide and dimethylsulfoxide, but poorly soluble in weakly coordinating solvents, and deflagrate in the heat. Both compounds have been characterised by 1H, 13C NMR and IR spectroscopies as well as by X-ray crystallography. H2dpzb(NO2)x crystallise readily as impact-insensitive dmso or thf solvates. Due to steric crowding at the (pyrazolyl group)–(benzene) bonds, H2dpzb(NO2)x adopt a twisted molecular geometry with extended (x = 2) or localised intermolecular hydrogen-bonding (x = 6) that involve the pyrazolyl H atoms and solvent of crystallisation. H2dpzb(NO2)6 reacts with base to form crystalline [B-H]2[dpzb(NO2)6], B = NEt3, which possesses remarkably high density ([B-H]2[dpzb(NO2)6]), or a powder consisting of Na2dpzb(NO2)6 (B = NaHCO3, crystallised as the coordination polymer Na(dmso)(dpzb(NO2)6). A mixture of H2dpzb(NO2)6, Zn(NO3)2, NEt3, dmso and water afforded the coordination compound [Zn(κ(O)-dmso)6]2[dpzb(NO2)6.

Two new energetic nitroaromatic compounds, 1,4-bis(1H-pyrazol-4'-yl)-2,5-dinitrobenzene (H2dpzb(NO2)2) and 1,4-bis(1H-3',5'-dinitropyrazol-4'-yl)-2,5-dinitrobenzene (H2dpzb(NO2)6), were prepared by nitration of 1,4-bis(1H-pyrazol-4'-yl)benzene (H2dpzb) with mixed acid. H2dpzb(NO2)x were isolated as yellow powders in moderate yields. They are stable under ambient conditions, soluble in dimethylformamide and dimethylsulfoxide, but poorly soluble in weakly coordinating solvents, and deflagrate in the heat. Both compounds have been characterised by 1H, 13C NMR and IR spectroscopies as well as by X-ray crystallography. H2dpzb(NO2)x crystallise readily as impact-insensitive dmso or thf solvates. Due to steric crowding at the (pyrazolyl group)–(benzene) bonds, H2dpzb(NO2)x adopt a twisted molecular geometry with extended (x = 2) or localised intermolecular hydrogen-bonding (x = 6) that involve the pyrazolyl H atoms and solvent of crystallisation. H2dpzb(NO2)6 reacts with base to form crystalline [B-H]2[dpzb(NO2)6], B = NEt3, which possesses remarkably high density ([B-H]2[dpzb(NO2)6]), or a powder consisting of Na2dpzb(NO2)6 (B = NaHCO3, crystallised as the coordination polymer Na(dmso)(dpzb(NO2)6). A mixture of H2dpzb(NO2)6, Zn(NO3)2, NEt3, dmso and water afforded the coordination compound [Zn(κ(O)-dmso)6]2[dpzb(NO2)6.

Benzene, 1, is a hard nut to crack. The hexagonal ring of carbon atoms each with one hydrogen atom attached has a much greater stability than its electronic structure, with an alternation of double and single carbon–carbon bonds, might suggest. But for reasons fully understood by chemists, that very alternation, corresponding to a continuous stabilizing cloud of electrons all around the ring, endows the hexagon with great stability and the ring persists unchanged through many reactions. The groups of atoms attached to the ring, though, may come and go, and the reaction type responsible for replacing them is commonly ‘electrophilic substitution’. Whereas the missiles of Reaction 15 sniff out nuclei by responding to their positive electric charge shining through depleted regions of electron clouds, electrophiles, electron lovers, are missiles that do the opposite. They sniff out the denser regions of electron clouds by responding to their negative charge. Let’s suppose you want to make, for purposes you are perhaps unwilling to reveal, some TNT; the initials denote trinitrotoluene. You could start with the common material toluene, which is a benzene ring with a methyl group (–CH3) in place of one H atom, 2. Your task is to replace three of the remaining ring H atoms with nitro groups, –NO2, to achieve 3. And not just any of the H atoms: you need the molecule to have a symmetrical array of these groups because other arrangements are less stable and therefore dangerous. It is known that a mixture of concentrated nitric and sulfuric acids contains the species called the ‘nitronium ion’, NO2+, 4, and this is the reagent you will use. Before we watch the reaction itself, it is instructive to see what happens when concentrated sulfuric acid and nitric acid are mixed. If we stand, suitably protected, in the mixture, we see a sulfuric acid molecule, H2SO4, thrust a proton onto a neighbouring nitric acid molecule, HNO3. (Funnily enough, according to the discussion in Reaction 2, nitric ‘acid’ is now acting as a base, a proton acceptor! I warned you of strange fish in deep waters.) The initial outcome of this transfer is unstable; it spits out an H2O molecule which wanders off into the crowd. We see the result: the formation of a nitronium ion, the agent of nitration and the species that carries out the reaction for you.