Mercury(II) bromide or mercuric bromide is an inorganic compound with the formula HgBr<sub>2</sub>. This white solid is a laboratory reagent. Like all mercury salts, it is highly toxic.
Mercury(II) bromide can be produced by reaction of metallic mercury with bromine.
Mercury(II) bromide is used as a reagent in the KoenigsâÂÂKnorr reaction, which forms glycoside linkages on carbohydrates.
It is also used to test for the presence of arsenic, as recommended by the European Pharmacopoeia. The arsenic in the sample is first converted to arsine gas by treatment with hydrogen. Arsine reacts with mercury(II) bromide:
The white mercury(II) bromide will turn yellow, brown, or black if arsenic is present in the sample.
Mercury(II) bromide reacts violently with elemental indium at high temperatures and, when exposed to potassium, can form shock-sensitive explosive mixtures.