Wikipedia
Bromine water
Bromine water is a highly oxidizing intense yellow mixture containing diatomic bromine Br at 2.8% dissolved in HO. It is often used as a reactive in chemical assays of recognition for substances which react with bromine in an aqueous environment with the halogenation mechanism. The most common compounds that react well with bromine water are phenols, alkenes, enols, the acetyl group, aniline and glucose. In addition, bromine water is commonly used to test for the presence of an alkene which contains a covalent bond which reacts with the bromine water which changes its colour from an intense yellow to a colourless solution.