How do you Brominate an aromatic compound?
Bromination is achieved with the help of AlBr3 (Lewis acid catalyst) as it polarizes the Br-Br bond. The polarization causes polarization causes the bromine atoms within the Br-Br bond to become more electrophilic. The presence of Br+ compared to Br2 alone is a much better electrophile that can then react with benzene.
Does bromine react with aromatic compounds?
Aromatic compounds react by electrophilic aromatic substitution reactions, in which the aromaticity of the ring system is preserved. For example, benzene reacts with bromine to form bromobenzene. Many functional groups can be added to aromatic compounds via electrophilic aromatic substitution reactions.
Which is the deactivating group for electrophilic aromatic substitution?
Certain functional groups can accept, rather than donate, a pi bond from the ring, resulting in a new lone pair on a substituent atom. Examples are NO2, carbonyl groups (C=O), sulfonyl, cyano (CN) among others. These groups are universally deactivating, slowing the rate of electrophilic aromatic substitution.
Why do aromatic hydrocarbons undergo substitution reactions?
Explanation: The aromatic structure provides significant additional stability to the molecule. Substitution reactions allow the aromatic structure to remain, whereas additions would change the C-C bonding away from being aromatic.
Why benzene does not react with bromine?
The six electrons in the π-system above and below the plane of the benzene ring are delocalised over the six carbon atoms, so the electron density is lower. The bromine cannot be polarised sufficiently to react, and the lower electron density does not attract the electrophile so strongly.
Is bromine electron-donating or withdrawing?
Nitro groups are electron-withdrawing groups, so bromine adds to the meta position. The main point to remember here is that electron-donating groups direct substitution to the ortho and para positions, while pi electron-withdrawing groups direct substitution to the meta position.
Is bromination endothermic?
In bromination, the reaction is endothermic, and the transition state resembles the products.
How is the selective bromination of activated aromatic compounds performed?
A simple, efficient and mild method for the selective bromination of activated aromatic compounds using ammonium bromide as the source of bromine and Oxone as the oxidant in methanol or water as solvent proceeds at ambient temperature in good yields without a catalyst.
How to make bromoarene from deactivated aromatics?
Highly deactivated aromatic compounds were smoothly monobrominated by treatment with N -bromosuccinimide (NBS) in concentrated sulfuric acid. Mild reaction conditions and simple workup provides a practical and commercially viable route for the synthesis of bromo compounds of deactivated aromatics in good yields.
Which is the best bromine for Ring bromination?
J. Chen, X. Xiong, Z. Chen, J. Huang, Synlett, 2015, 26, 2831-2834. A highly efficient, rapid and regioselective protocol for the ring bromination of aromatic compounds under mild conditions can be conducted with ammonium bromide as a source of bromine source and Oxone as an oxidant.
How does vanadium pentoxide promote the bromination of organic substrates?
Vanadium pentoxide very effectively promotes the bromination of organic substrates, including selective bromination of some aromatics, by tetrabutylammonium bromide in the presence of hydrogen peroxide. The reaction offers mild conditions, high selectivity, yield, and reaction rate, and redundancy of bromine and hydrobromic acid.