Chloramine and hydroxylamine

  The reactions of NH₃ and Cl₂ (diluted with N₂) or aqueous NaOCl yield chloramine the compound responsible for the odour of water containing nitrogenous matter that has been sterilized with Cl₂. Chloramine is unstable, and violently explosive, and is usually handled in dilute solutions (e.g. in H₂O or Et₂O). Its reaction with Me₂NH yields the rocket fuel 1,1-dimethylhydrazine.

    Reaction below is one of several routes to hydroxylamine, NH₂OH, which is usually handled as a salt (e.g. the sulfate) or in aqueous solution. The free base can be obtained from its salts by treatment with NaOMe in MeOH.

  Pure NH₂OH forms white, hygroscopic crystals  which melt at 306K and explode at higher temperatures.   It is a weaker base than NH₃ or N₂H₄. Many of its reactions arise from the great variety of redox reactions in which it takes part in aqueous solution, e.g. it reduces Fe(III) in acidic solution  but oxidizes Fe(II) in the presence of alkali .

   More powerful oxidizing agents (e.g. [BrO₃]^-) oxidize NH₂OH to HNO₃. The formation of N₂O in most oxidations of NH₂OH is an interesting example of the triumph of kinetic over thermodynamic factors. Consideration of the potential diagram  in Figure 1.2 shows that, on thermodynamic grounds, the expected product from the action of weak oxidizing agents on

[NH₃OH]‏ (i.e. NH₂OH in acidic solution) would be N₂, but it seems that the reaction occurs by steps below. A use of NH₂OH is as an antioxidant in photographic developers.

Figure 1.2 also shows that, at pH= 0, [NH₃OH]‏ is unstable with respect to disproportionation into N₂ and [NH₄]‏ or [N₂H₅]‏; in fact, hydroxylamine does slowly decompose to N₂ and NH₃.