Monochloramine, NH₂Cl

Gattermann came to the conclusion that the chlorination of ammonia occurs in three stages:

1. NH₃ + Cl₂ = NH₂Cl (monochloramine) + HCl,
2. NH₂Cl + Cl₂ = NHCl₂ (dichloramine) + HCl,
3. NHCl₂ + Cl₂ = NCl₃ (trichloramine) + HCl;

but it was not found possible to isolate either mono- or di-chloramine by this method. Raschig,5 however, prepared monochloramine by mixing dilute equimolecular solutions of ammonia and sodium hypochlorite, and distilling the mixture at low temperatures in a vacuum:

NH₃ + NaOCl = NH₂Cl + NaOH.

An unstable yellow liquid is obtained which can be solidified into colourless unstable crystals with melting-point -66° C.

Monochloramine is also produced by the hydrolysis of potassium cliloramino-sulphonate with dilute mineral acids:

NHCl.SO₃K + H₂O = NH₂Cl + KHSO₄.

Monochloramine is decomposed by alkalies with the formation of ammonia and nitrogen:

(i) 3NH₂Cl + 3KOH = NH₃ + N₂ + 3KCl + 3H₂O,

(ii) 3NH₂Cl + 2NH₃ = N₂ + 3NH₄Cl;

but at the same time some of the ammonia reacts with the chloramine to produce a small amount of hydrazine hydrochloride:

(iii) NH₂Cl + NH₃ = N₂H₄.HCl.

Monochloramine reacts with potassium iodide to form nitrogen iodide.