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If bromine water is added to aniline, the bromine water is decolourised and a white precipitate of 2,4,6-tribromoaniline is formed. To generate the mono-substituted product, a protection with acetyl chloride is required: Aniline can react with bromine even in room temperatures in water. Acetyl chloride is added to prevent tribromination.
2,4,6-Tribromoaniline can be prepared by treating bromine water with aniline in a solution of acetic acid or dilute hydrochloric acid: [1] By reacting bromine with aniline in water, a white precipitate immediately forms and that is 2,4,6-tribromoaniline
The formation of a brominated phenol (i.e. 2,4,6-tribromophenol) or aniline (i.e. 2,4,6-tribromoaniline) in form of a white precipitate indicates that the unknown was a phenol or aniline. The more unsaturated an unknown is, the more bromine it reacts with, and the less coloured the solution will appear. [1]
Bromine water, Br 2. Bromine water is an oxidizing, intense brown mixture containing diatomic bromine (Br 2) dissolved in water (H 2 O). [1] 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, mainly unsaturated carbon compounds (carbon compounds with 1 or more double or triple bond(s)).
4-Bromoaniline is a compound where an aniline molecule is substituted with a bromine atom on the para position. Commercially available, this compound may be used as a building block, e.g. in the preparation of monobrominated biphenyl via the Gomberg-Bachmann reaction .
The anion reacts with bromine in an α-substitution reaction to give an N-bromoamide. Base abstraction of the remaining amide proton gives a bromoamide anion. The bromoamide anion rearranges as the R group attached to the carbonyl carbon migrates to nitrogen at the same time the bromide ion leaves, giving an isocyanate.
For example, 2,4-dinitrochlorobenzene reacts in basic solution to give a phenol. Unlike in most other substitution reactions, fluoride is the best leaving group, and iodide the worst. [ 16 ] A 2018 paper indicates that this situation may actually be rather common, occurring in systems that were previously assumed to proceed via S N Ar mechanisms.
The classic case is sodium bromide, which fully dissociates in water: NaBr → Na + + Br −. Hydrogen bromide, which is a diatomic molecule, takes on salt-like properties upon contact with water to give an ionic solution called hydrobromic acid. The process is often described simplistically as involving formation of the hydronium salt of bromide: