Nitrogen tribromide explained

Nitrogen tribromide is a chemical compound with the formula NBr₃. It is extremely explosive in its pure form, even at −100 °C, and was not isolated until 1975. It is a deep-red and volatile solid.

Preparation

NBr₃ was first prepared by reaction of bistrimethylsilylbromamine (bis(trimethylsilyl)amine bromide) with bromine monochloride (with trimethylsilyl chloride as byproduct) at −87 °C according to the following equation:

(Me₃Si)₂NBr + 2 BrCl → NBr₃ + 2

where "Me" is a methyl group.

NBr₃ can be produced by the reaction of bromine or hypobromite and ammonia in a dilute aqueous buffer solution.^[1] It can also be prepared by the reaction of bromine and bromine azide.^[2] Ammonia and bromine undergo glow discharge, and after treatment, red NBr₃·6NH₃ can be obtained.^[3] Pure nitrogen NBr₃ was only produced in 1975.^[4]

Reactions

Nitrogen tribromide reacts instantly with ammonia in dichloromethane solution at −87 °C to yield NBrH₂.^[5]

NBr₃ + 2 NH₃ → 3 NH₂Br

It also reacts with iodine in dichloromethane solution at −87 °C to produce NBr₂I, which is a red-brown solid that stable up to -20 °C.^[5]

NBr₃ + I₂ → NBr₂I + IBr

Notes and References

1. Galal-Gorchev . Hend . Morris . J. Carrell . Jun 1965 . Formation and Stability of Bromamide, Bromimide, and Nitrogen Tribromide in Aqueous Solution . Inorganic Chemistry . 4 . 6 . 899–905 . 10.1021/ic50028a029 . 0020-1669.
2. Klapötke . Thomas M. . 1997-01-01 . The reaction of bromine azide with bromine . Polyhedron . 16 . 15 . 2701–2704 . 10.1016/S0277-5387(96)00586-4 . 0277-5387.
3. Schmeisser . Martin . 1941-05-07 . Über Bromstickstoff . Zeitschrift für anorganische und allgemeine Chemie . 246 . 3 . 284–302 . 10.1002/zaac.19412460305 . 0863-1786.
4. Jander . Jochen . Knackmuss . Jürgen . Thiedemann . Klaus-Ulrich . 1975-06-01 . Notizen: Darstellung und Isolierung von Stickstofftribromid NBr₃ und Stickstoffdibromidmonojodid NBr₂J / Preparation and Isolation of Nitrogentribromide NBr₃ and Nitrogendibromidemonoiodide NBr₂I . Zeitschrift für Naturforschung B . 30 . 5–6 . 464–465 . 10.1515/znb-1975-5-633 . 1865-7117. free .
5. Book: Matyáš . Robert . Pachman . Jiří. . Primary explosives . Springer . Berlin . 2013 . 978-3-642-28436-6 . 832350093 . 294.