THE PREPARATION OF CARBONYL DIBROMIDE

Carbonyl dibromide is not commercially available, and therefore must be prepared when required. It is conveniently prepared by the oxidation of tetrabromomethane with sulfuric acid  

Concentrated sulfuric acid (20 cm ) was slowly added, via a dropping funnel, to molten tetrabromomethane (20 g 0.06 mol) held in a reaction flask at about 90 °C. The flask, connected to a simple distillation unit, was then heated to 150-170 °C for 2 h, and the products collected in a high surface area trap eooled to -10 °C. 

The commercial availability of carbonyl chloride fluoride is, to say the least, variable appearing on suppliers lists e.g. Fluorochem and Ozark-Mahoning) in some years, and not in others. When available, this material has a price that is disproportionately high relative to phosgene and carbonyl difluoride, reflecting the speciality nature of the compound and the absence of any bulk production. 

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