Mechanism for the Chloride‐Catalyzed Thermal Decomposition of Ammonium Nitrate

A kinetic study of the thermal decomposition of NH₄NO₃ in the presence of NaCl has been carried out using the differential kinetic technique previously described. The rate law for N₂ evolution is of the form k₁(NH₄⁺)+k₂(NH₄⁺) (Cl^—)^½. A radical mechanism is proposed in which the role of chloride is catalytic, being oxidized by NO₂⁺ to Cl atoms which are reduced back by NH₄⁺ and NH₃. These hydrogen abstraction reactions leave NH₃⁺ and NH₂, respectively, in reaction cages in which subsequent radical recombinations yield nitramide and nitrosamine as precursors for N₂O and N₂. Parallel Cl atom recombinations give Cl₂, part of which escapes by volatilization, the rest reacting with NH₃ to provide a second source of N₂.