The Interaction between Otto Fuel II and Aqueous Hydroxylammonium Perchlorate (HAP), Part III: Depletion of Components within the Reacting Liquids

Gas chromatography (GC) with a Flame Ionisation Detector (FID) has been used to determine changes in the concentrations of the components of Otto Fuel II (OF) in contact with an 82% aqueous solution of hydroxylammonium perchlorate (HAP) in sealed vials at 31.7 °C during the period leading up to auto‐ignition of the two liquids. The concentration of hydroxylamine in HAP was monitored over the same period using a titration method. It was found that 2‐nitrodiphenylamine (2NDPA), the stabiliser in the OF, is completely consumed after about 65–70 h and that the concentration of hydroxylamine begins to fall at this point. 1,2‐Propanediol dinitrate (propylene glycol dinitrate, PGDN), the energetic component in the OF, is not depleted significantly until after about 90 h. The evolution of nitrous oxide (N₂O) between 65 and 90 h is attributed to the reaction of the hydroxylammonium ion with nitrous acids produced by PGDN decomposition at the liquid‐liquid interface. Carbon dioxide (CO₂) is evolved after ~ 90 h and is attributed to PGDN decomposition. HAP and PGDN are each thought to contribute to N₂O evolution after ~ 90 h.     

The Interaction between Otto Fuel II and Aqueous Hydroxylammonium Perchlorate (HAP), Part II: Gas Evolution and Changes in HAP Solution Acidity

Headspace gas analysis has shown that nitrous oxide (N₂O) is the principal gas evolved during contact between small volumes of Otto Fuel II (OF) and 82% aqueous hydroxylammonium perchlorate (HAP) at temperatures close to ambient. The gas is produced mainly from the 82% HAP layer and is generated in significant amounts only after the OF has become blackened as a result of extreme degradation. The pH of the HAP solution falls during contact with OF and the OF blackening point is the same for each of three storage temperatures investigated, suggesting that the production of N₂O may depend upon the attainment of a specific HAP solution acidity. It is suggested that the propyleneglycol dinitrate (PGDN) component in OF undergoes acid hydrolysis at the liquid/liquid interface and that the nitric acid produced leads to the decrease in HAP solution pH and to stabilizer depletion in OF. Experiments involving contact between 82% HAP and the other components of OF confirm the key role of PGDN: in its absence there is no change in HAP solution acidity, no gas evolution and no violent reaction between the two liquids.     

Carbenes Made Easy: Formation of Unsymmetrically Substituted N‐Heterocyclic Carbene Complexes of Palladium(II), Platinum(II) and Gold(I) from Coordinated Isonitriles and their Catalytic Activity

From palladium(II) or platinum(II) bis(isonitrile) complexes and from gold(I) isonitrile complexes, both easily available from simple precursors, the corresponding mono‐N‐heterocyclic carbene (NHC) complexes could be obtained selectively in good yields under very mild conditions. The reagents are simple β‐chloroammonium salts in the presence of a weak base. Unsymmetric NHC complexes are accessible. Thus over only two steps from simple metal precursors a broad variety of NHC complexes is available, the method is ideal to quickly assemble catalyst libraries. The palladium complexes are active pre‐catalysts in Suzuki cross‐coupling even with the additional isonitrile ligand on palladium.