New Takes on Nitrate Ester Chemistry: Salts with Oxygen‐Rich Ammonium Cations

Abstract

Recent efforts have established the possibility of pharmaceutical applications for several nitrate ester salts, and their Abstract: Nitrate (anion) salts with nitroxy-functionalized ammonium cations were synthesized. Several revealed surprising thermal and hydrolytic stability. Various physical properties were measured, and Gibbs free energy (DG r (298)) differences between the salts and postulated products of their thermal decomposition were computed. The computed differences indicate that salts with cations that have more than one nitroxy group are endothermic at 298 K. Nevertheless, the stability observed for some salts with this property indicates that kinetic barriers are sufficient to prevent facile decomposition at this temperature. This is in contrast to the case observed for nitrate salts of nitroxy-functionalized ammonium cations with acidic protons.

Property Predictions for Nitrate Salts with Nitroxy-Functionalized Cations

“…The volumes determined for 1-methyl-3Himidazolium (23) and 1,3-dimethylimidazolium (24) are in good agreement with those calculated by Gutowski et al (2005), and the volumes for 1-methyl-4H-tetrazolium (82) nitrate, 1,4-dimethyltetrazolium (88) nitrate, and 1,3,5-trimethyltetrazolium (90) nitrate are in good agreement with those calculated by Zhang et al (2010). Drake et al, 2009. c Wagman et al, 1982.…”

“…Results of prior studies conducted under the EQBR program have been reported previously (Drake et al, 2009;McQuaid and Drake, 2010). Figure 1 shows cations of nitrate (anion) salts that were isolated and had various properties characterized (Drake et al, 2009). Of this group, only 2-nitroxy-N, N, N-trimethylethanammonium (1) nitrate was found to have thermal stability sufficient for rocket propellant applications.…”

“…Because nitroxyalkyl-substituted amines are poor bases, Drake et al (2009) synthesized their corresponding salts by first quaternizing/methylating their (more basic) hydroxyalkylamine analog, then nitrating the product. As such, equation 1 does not correlate with this two-step process, and the method developed by Gutowski et al is therefore of limited value with respect to predicting the potential for synthesizing a salt via the two steps.…”

Designing Explosive Poly(Ionic Liquid)s as Novel Energetic Polymers

“…The nitrato group has been demonstrated to be useful in energetic compounds. [15] The introduction of an itrato group into the cationic structureo fI Ls was accomplished through the reaction of 1-vinylimidazole and 2-bromoethyl nitrate. After the polymerization and subsequentm etathesis reactions with KNO 3 /KN(NO 2 ) 2 /KC(NO 2 ) 3 , E-PIL-ONO 2 -1, E-PIL-ONO 2 -2,a nd E-PIL-ONO 2 -3 were obtained, respectively.T he introduced oxygen-rich nitro group could improve the oxygen balance of E-PILs, and led to an enhanced detonation performance.…”

Nitrato‐Functionalized Task‐Specific Ionic Liquids as Attractive Hypergolic Rocket Fuels

“…In fact, the densities of four nitrato‐functionalized HILs (HILs 1–4, Table ) are obviously higher than most known dicyanamide‐based ionic liquids (around 0.9–1.1 g cm −3 ) and unsymmetric dimethyl hydrazine (UDMH; 0.79 g cm −3 ), which indicates that nitrato‐functionalized HILs have higher loading capacity than traditional hydrazine‐based fuels. The high densities of nitrato‐functionalized HILs may result from their multiple hydrogen bonds C−H ⋅⋅⋅ O between aromatic/aliphatic C−H bonds and nitrato group . With respect to hydroxyl‐functionalized HILs (HILs 5–8), because of only one oxygen atom in the molecule, their limited C−H ⋅⋅⋅ O hydrogen bonds result in their slightly higher densities than the non‐functional HILs (HILs 9–12, Table ).…”