Question
Write a note on halogenation of phenol.
✓
Answer
$\rightarrow$ Halogenation: On treating phenol with bromine, different reaction products are formed under different experimental conditions.
$(a)$ When the reaction is carried out in solvents of low polarity such as $CHCl_3$ or $CS_2$ and at low temperature, monobromophenols are formed.
$\rightarrow$ The usual halogenation of benzene takes place in the presence of a Lewis acid, such as $FeBr^3,$ which polarises the halogen molecule. In case of phenol, the polarization of bromine molecule takes place even in the absence of Lewis acid. It is due to the highly activating effect of $-OH$ group attached to the benzene ring.
$(b)$ When phenol is treated with bromine water, $2, 4, 6-$tribromophenol is formed as white precipitate.
$(a)$ When the reaction is carried out in solvents of low polarity such as $CHCl_3$ or $CS_2$ and at low temperature, monobromophenols are formed.
$\rightarrow$ The usual halogenation of benzene takes place in the presence of a Lewis acid, such as $FeBr^3,$ which polarises the halogen molecule. In case of phenol, the polarization of bromine molecule takes place even in the absence of Lewis acid. It is due to the highly activating effect of $-OH$ group attached to the benzene ring.
$(b)$ When phenol is treated with bromine water, $2, 4, 6-$tribromophenol is formed as white precipitate.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Explain with chemical reactions, the reaction of carboxylic acids with ammonia.
How to prepare butan-1-ol by reduction of various derivatives of acids.
An unknown aldehyde ‘$A’$ on reacting with alkali gives a $ \beta-$ hydroxy aldehyde, which loses water to form an unsaturated aldehyde, $ 2-$ butenal. Another aldehyde ‘$B’$ undergoes disproportionation reaction in the presence of conc. alkali to form products $C$ and $D. C$ is an arylalcohol with the formula, $\ce{C_7H_8O}$.
→- Identify $A$ and $B$.
- Write the sequence of reactions involved.
- Name the product, when ‘$B$’ reacts with zinc amalgam and hydrochloric acid.
An antifreeze solution is prepared from 222.6 g of thylene glycol (C2H6O2) and 200 g of water. Calculate the molality of the solution. If the density of the solution is $1.072 g mL ^{-1}$ , then what shall be the molarity of the solution?
→Answer thefollowing:
→- Haloalkanes easily dissolve in organic solvents,why?
- What is known as a racemic mixture? Give an example.
- Of the two bromoderivatives $,\ce{C_6H_5CH(CH_3)Br}$ and $\ce{C_6H_5CH(C_6H_5) Br},$ which one ismore reactive in $\ce{S_N1}$ substitution reaction and why?
Compare the chemistry of actinoids with that of the lanthanoids with special reference to: Chemical reactivity
Explain Crystal field splitting in tetrahedral complax.
What are enzymes?
Give reasons-
(a) The bond length of C-O bond in phenol is less than that of methanol.
(b) C-O-C bond angle present in ether is more than tetrahedral angle.
(c) Boiling point decreases on increasing branching in isomeric alcohols.
(a) The bond length of C-O bond in phenol is less than that of methanol.
(b) C-O-C bond angle present in ether is more than tetrahedral angle.
(c) Boiling point decreases on increasing branching in isomeric alcohols.
(a) How will you prepare phenol from benzenediazonium chloride?
(b) How will you convert salicylic acid into phenol?
(b) How will you convert salicylic acid into phenol?