Phenol + bromine water →white precipitate. The product is (a) o-bromophenol (b) p -bromophenol (

step 1 In this problem I can write the reaction as just look at it carefully. This is phenol in presenc

Phenol + bromine water →white precipitate. The product is...

Key Concepts

Electrophilic Aromatic Substitution

This is a core reaction mechanism in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. It involves the formation of a sigma complex that temporarily disrupts the aromatic system, followed by deprotonation to restore aromaticity. This mechanism explains how substituents on a benzene ring are substituted with electrophiles, such as bromine from bromine water.

Activating Effects of Hydroxyl Groups

Hydroxyl groups attached to an aromatic ring act as strong electron-donating substituents through resonance, thereby increasing the ring's electron density. This activation makes the benzene ring more reactive towards electrophilic aromatic substitution, directing incoming electrophiles to ortho and para positions relative to the hydroxyl group.

Bromination Reaction Conditions with Bromine Water

Bromine water is an electrophilic reagent used in halogenation reactions. In the presence of an activated aromatic system, such as a phenolic ring, bromine water facilitates electrophilic aromatic substitution without the need for a catalyst. The reaction conditions often lead to multiple substitutions depending on the reactivity of the aromatic compound.

Polysubstitution in Activated Aromatic Compounds

Due to the high electron density imparted by activating groups like hydroxyl, multiple electrophilic substitutions can occur on the aromatic ring. This can lead to polysubstituted products, and in some cases, such as with phenol under bromine water conditions, the formation of a tribrominated product occurs, which may precipitate out of solution due to its low solubility.

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