ammonia with chlorine gas (diluted with nitrogen gas): 2 NH3 + Cl2 NH2Cl + NH4Cl Pure chloramine can be prepared by passing fluoroamine through calcium chloride: 2 NH2F + CaCl2 → 2 NH2Cl + CaF2 Decomposition The covalent N−Cl bonds of chloramines are readily hydrolyzed with release of hypochlorous acid: RR′NCl + H2O RR′NH + HOCl The quantitative hydrolysis constant (K value) is used to express the bactericidal power of chloramines, which depends on their generating hypochlorous acid in water. It is expressed by the equation below, and is generally in the range 10−4 to 10−10 ( for monochloramine): In aqueous solution, chloramine slowly decomposes to dinitrogen and ammonium chloride in a neutral or mildly alkaline (pH ≤ 11) medium: 3 NH2Cl → N2 + NH4Cl + 2 HCl However, only a few percent of a 0.1 M chloramine solution in water decomposes according to the formula in several weeks. At pH values above 11, the following reaction with hydroxide ions slowly occurs: 3 NH2Cl + 3 OH− → NH3 + N2 + 3 Cl− + 3 H2O In an acidic medium at pH values of around 4, chloramine disproportionates to form dichloramine, which in turn disproportionates again at pH values below 3 to form nitrogen trichloride: 2 NH2Cl + H+ NHCl2 + 3 NHCl2 + H+ 2 NCl3 + At low pH values, nitrogen trichloride dominates and at pH 3–5 dichloramine dominates. These equilibria are disturbed by the irreversible decomposition of both compounds: NHCl2 + NCl3 + 2 H2O → N2 + 3 HCl + 2 HOCl Reactions In water, chloramine is pH-neutral. It is an oxidizing agent (acidic solution: , in basic solution ): NH2Cl + 2 H+ + 2 e− → + Cl− Reactions of chloramine include radical, nucleophilic, and electrophilic substitution of chlorine, electrophilic substitution of hydrogen, and oxidative additions. Chloramine can, like hypochlorous acid, donate positively charged chlorine in reactions with nucleophiles (Nu−): Nu− + NH3Cl+ → NuCl + NH3 Examples of chlorination reactions include transformations to dichloramine and nitrogen trichloride in acidic medium, as described in the decomposition section. Chloramine may also aminate nucleophiles (electrophilic amination): Nu− + NH2Cl → NuNH2 + Cl− The amination of ammonia with chloramine to form hydrazine is an example of this mechanism seen in the Olin Raschig process: NH2Cl + NH3 + NaOH → N2H4 + NaCl + H2O Chloramine electrophilically aminates itself in neutral and alkaline media