Analysis of an explosion accident of nitrogen trichloride in a waste liquid containing ammonium ion and platinum black.

Five liters of sodium hypochlorite aqueous solution (12 mass%) was poured into 300 L of liquid waste containing ammonium ion of about 1.8 mol/L in a 500 L tank in a plant area; then, two minutes later the solution exploded with a flash on March 30th, 2005. The tank cover, the fluorescent lamp and the air duct were broken by the blast wave. Thus, we have conducted 40 runs of laboratory-scale explosion tests under various conditions (solution concentrations of (NH4)2SO4 and NaClO, temperatures, Pt catalysts, pH, etc.) to investigate the causes for such an explosion. When solutions of ammonium sulfate and sodium hypochlorite are mixed in the presence of platinum black, explosions result. This is ascribable to the formation of explosive nitrogen trichloride (NCl3). In the case where it is necessary to mix these 2 solutions (ammonium sulfate and sodium hypochlorite) in the presence of platinum black, the following conditions would reduce a probability of explosion; the initial concentration of NH4(+) should be less than 3 mol/L and the pH should be higher than 6. The hypochlorite solution (in 1/10 in volume) to be added at room temperature is recommended to be less than 0.6 mol/L.

Hexaaquazinc(II) dipicrate trihydrate.

In the crystal structure of the title compound, [Zn(H2O)6](C(6)H(2)N(3)O(7))2.3H2O, the zinc cation complexes and picrate anions are stacked separately, extending along the b axis. No picrate species ligate to the metal cation. This lack of picrate coordination is atypical among metal picrate salts. We speculate that the size of the metal-aqua complex as related to the intermolecular distance of the picrate anions in the pi stack can be a measure of the formation of such separated stacks in the crystal structures of divalent metal complexes with picrate anions. Picrate ions are linked to each other with short intermolecular C...C contacts of 3.223 (6) and 3.194 (6) A in the stack.

Thermal hazard of iron picrate.

Iron picrate (FePic) was synthesized under conditions similar to those that result in the natural deterioration of chemical weapons. Its thermal hazard was investigated by comparing it with iron picrate obtained by the chemical synthesis method (FePic(Ba)). FePic has eight or more water molecules of crystallization and consists of a mixture of various hydrates. It shows low sensitivity to friction and drop hammer tests due to the large number of water molecules of crystallization. Under the experimental conditions of the thermal analysis, the hydrated iron picrates began to decompose before being dehydrated to form the anhydrous salt. Prolonged holding under natural environmental conditions does not appear to result in formation of the dangerous anhydrous salt. Based on the observed heating rate dependence, it is thought that the hydrated iron picrate should start to decompose before dehydration to the anhydrous salt occurs when subjected to a large heating rate.

Hexaaquairon(II) dipicrate dihydrate.

In the crystal structure of the title compound, [Fe(H(2)O)(6)](C(6)H(2)N(3)O(7))(2).2H(2)O, the centrosymmetric cationic iron complexes and picrate anions form separate stacks extending along the b axis. No picrate species ligate to the metal cation. Picrate ions are linked to one another in the stack via short intermolecular C.C contacts of 3.083 (4) and 3.055 (4) A. Variable-temperature X-ray diffraction measurements performed between room temperature and 93 K showed a linear decrease of the lattice parameters, suggesting that there is no phase transition.