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4-Fluorobromobenzene is synthesized via bromination of fluorobenzene in the presence of a Lewis acid catalyst such as iron(III) bromide or aluminium tribromide. [2]4-Bromofluorobenzene is regarded by the Toxic Substances Control Act as a high production volume chemical, that is, a chemical that 1 million pounds (about 500 tonnes) per year is either produced in or imported to the United States.
In contrast, the boiling points of PhF and benzene are very similar, differing by only 4 °C. It is considerably more polar than benzene, with a dielectric constant of 5.42 compared to 2.28 for benzene at 298 K. [4] Fluorobenzene is a relatively inert compound reflecting the strength of the C–F bond.
Bromoform was discovered in 1832 by Löwig who distilled a mixture of bromal and potassium hydroxide, as analogous to preparation of chloroform from chloral. [5]Bromoform can be prepared by the haloform reaction using acetone and sodium hypobromite, by the electrolysis of potassium bromide in ethanol, or by treating chloroform with aluminium bromide.
[3] Bromobenzene is used to introduce a phenyl group into other compounds. One method involves its conversion to the Grignard reagent, phenylmagnesium bromide. This reagent can be used, e.g. in the reaction with carbon dioxide to prepare benzoic acid. [4] Other methods involve palladium-catalyzed coupling reactions, such as the Suzuki reaction.
Bromophenols (as well as PBDEs) were detected in 88% of samples, with 2,4,6-Tribromophenol present in 84% of breast milk samples alone. This was widely reported [ 2 ] [ 3 ] and has raised questions about restricting the use of brominated flame retardants in the future.
1-Bromo-3-chlorobenzene: by (3-chlorophenyl)trimethylgermanium by electrophilic substitution [2] [better source needed] 1-Bromo-4-chlorobenzene: From a derivative of (4-bromophenyl)silane using N-bromosuccinimide [3] From 4-chlorophenol using triphenylphosphine dibromide [4] or phenylphosphorus tetrachloride [5]
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Strong Lewis or protic acids are typically required for the reaction (e.g. TiCl 4, BF 3, MeSO 3 H). These promoters are not compatible with sensitive functional groups, limiting the substrate scope. Despite the mechanistic possibility for catalysis, multiple equivalents of the promoter are often required in order to effect the reaction.