Carbonyl bromide

Carbonyl bromide, also known as bromophosgene, is a carbon oxohalide and a bromine analogue of phosgene, with the chemical formula. It is a colorless liquid. Carbonyl bromide is a decomposition product of halon compounds used in fire extinguishers.

Synthesis and reactions

Carbonyl bromide is formed by the oxidation of carbon tetrabromide with sulfuric acid:
In contrast to phosgene, carbonyl bromide cannot be produced efficiently by halogenation of carbon monoxide. The bromination of carbon monoxide follows this equation:
But the process is slow at room temperature. Increasing temperature, in order to increase the reaction rate, results in a shift of the chemical equilibrium towards the reactants.
Carbonyl bromide slowly decomposes to carbon monoxide and elemental bromine even at low temperatures. It is also sensitive to hydrolysis, breaking down into hydrogen bromide and carbon dioxide.