Ammonium-electron decomposition

Some limitations of optical microscopy were apparent in applying [247—249] the technique to supplement kinetic investigations of the low temperature decomposition of ammonium perchlorate (AP), a particularly extensively studied solid phase rate process [59]. The porous residue is opaque. Scanning electron microscopy showed that decomposition was initiated at active sites scattered across surfaces and reaction resulted in the formation of square holes on m-faces and rhombic holes on c-faces. These sites of nucleation were identified [211] as points of intersection of line dislocations with an external boundary face and the kinetic implications of the observed mode of nucleation and growth have been discussed [211]. 

In Chapter 7, it was shown how the enthalpy of decomposition of an ammonium salt can be used to calculate the proton affinity of the anion. The proton affinity is a gas-phase property (as is electron affinity) that gives the intrinsic basidty of a species. The reaction of H+ with a base B can be shown as... 

Trithiophosphonic acids (RPS3H2) are thermally unstable compounds, undergoing decomposition reactions at temperatures sometimes as low as — 10°C depending upon the electronic and steric properties of the R substituent. Decomposition usually occurs via a condensation reaction (similar to that observed for dithiophosphinic acids - Equation 21) to give the di-thiadiphosphatene disulfide and eliminate H2S (Equation 35).48 Similar to dithiophosphinic acids, their metal and ammonium salts are far more thermally stable and are therefore the preferred synthetic target in most cases. 

The dinitramide ion is stable in both acidic and basic solutions between pH 1-15 at room temperature but is slowly decomposed in the presence of strong concentrated acid. In contrast to alkyl V,V-dinitramines (Section 6.11.2) where the central nitrogen atom is highly electron deficient, the dinitramide anion has its negative charge delocalized over both nitrogen and oxygen atoms with the consequence that the N-N bonds are less susceptible to rupture. However, the dinitramide anion is not as stable as the nitrate anion ammonium dinitramide melts at 92 °C and decomposition starts at 130 °C. 

Diamonium pentachlorooxomolybdate(V) is an emerald green solid, stable in air. It is hygroscopic and should be stored in a stoppered vial in a desiccator. In concentrated HC1, a solution (> 10M) of the compound is green. In dilute HC1 (< 10M) the solution is greenish-brown or borwnish-red. The compound undergoes extensive ionic dissociation in aqueous solution. It is insoluble in benzene, chloroform, dichloromethane, and carbon tetrachloride. It is soluble (with decomposition) in ethanol, methanol, acetone, and pyridine a white solid of ammonium chloride precipitates from all these solutions immediately. The compound dissolves in dimethyl sulfoxide without decomposition. The electronic spectrum in 10 M HC1 contains the following absorptions 14,100(emax = 11), 22,500(emax = 10), 28,200(emax = 570),... 

Chretien and Woringer [34] described the preparation of silver cyanamide from calcium cyanamide by the action of silver nitrate and also described its explosive properties. Montagu-Pollock [35] described a method for growing large crystals of the salt from its aqueous solution in the presence of ammonium nitrate, ammonia and a surface active agent. Bowden and Montagu-Pollock [36] and Montagu-Pollock [35] studied the slow decomposition of the crystals when heated at temperatures from 150 to 360°C. The course of decomposition was studied by electron microscope. 

An electron spin resonance study by Hyde and Freeman [12] revealed that ammonia radical ion NH form when ammonium perchlorate is exposed to X-rays. This radical ion was found to be stable in the ammonium perchlorate lattice up to 120°C. It is not formed during thermal decomposition and is not present in ammonium perchlorate sublimate. 

The introduction of silver ions which act as electron traps enhances the radiation-induced changes in the thermal decomposition of ammonium perchlorate. Irradiated samples containing silver show thermal decomposition similar to samples without silver, but which received a considerably greater radiation dose. 

The results of the characterization of the product synthesized with Fourier transformation infra-red spectrophotometer (FTIR), X-ray diffractometer (XRD), scanning electron mirror microscope (SEM) and the transmission electron mirror microscope (TEM) illustrate that the product synthesized by the process of double decomposition-precipitation with calcium nitrate and di-ammonium phosphate as the reactants in the SCISR consists of well dispersed particles of about 15 nm in diameter and 50-70 nm long, having a very regular shape and appearance and is confirmed to be hydroxylapatite. 

It was found that this heterogeneous reaction can be stopped by the addition of small amounts of lithium. It is likely that lithium with its higher electrode potential is able to prevent the self-ionization of liquid ammonia, and the heterogeneous reaction between ammonium in solution and liquid ammonia is inhibited. When this heterogeneous reaction is prevented, the decomposition follows a perfectly satisfactory second-order reaction, and the temperature must be raised up to the range from zero to 20° in order to obtain a measurable reaction rate. The reaction is satisfactorily explained on the assumption that ammonium dissociates in mercury giving ammonium ions and free electrons NH4—>NH4+ -be . The older view that the ammonium exists as a free radical, NH4, seems less likely. Such a radical would be unstable and it would not be expected to have such a long life. Ammonium ions, however, are more stable. 

Organic dinitramines of the type RCH2CH2N(N02)2 with an electron accepting group (R = CN, CHO, COR, COOR, or NO2) eliminate ammonium dinitramide and acrylic compounds H2C=CHR during decomposition in aqueous solutions of ammonia. 

The experiments of Rosser, Inami and Wise [57] were the continuation of their w ork on catalytic decomposition of ammonium nitrate [74]. They examined the action of copper chromite. They found that it acted at the early stage of the reaction and its action disappeared after copper diromiie was oxidized by the products of catalytic reaction. Cobalt oxide was found to be an exceptional catalyst it produced NOCl and NO2CI as major products and only a trace quantity of N2O3. Tlic authors came to the conclusion that copper chromite catalysed thermal decomposition of AP according to an electron transfer mechanism (4). 

---