medium difficulty6 min

Important Reactions of Alcohols and Phenols

Alcohols undergo reactions such as esterification, dehydration and oxidation, while phenols undergo electrophilic substitution reactions such as bromination, nitration and Reimer-Tiemann reaction.

In one line: Alcohols react at -OH or nearby carbon; phenol's ring reacts at ortho and para positions.

Practice This Concept

Understand it

Alcohol reactions are controlled by the O-H bond and the carbon bearing -OH.
Esterification forms esters with carboxylic acids or acid derivatives.
Dehydration removes water to form alkenes under acidic conditions.
Oxidation of primary alcohols can give aldehydes and acids, while secondary alcohols give ketones.
Phenol activates the benzene ring toward electrophilic substitution, especially at ortho and para positions.
With bromine water, phenol gives 2,4,6-tribromophenol.
In the Reimer-Tiemann reaction, phenol reacts with chloroform and base followed by acidification to give salicylaldehyde as the major product.

Example

Phenol with bromine water gives a white precipitate of 2,4,6-tribromophenol.

Rule to remember

Key patterns: alcohol + carboxylic acid with acid gives ester; alcohol under acid and heat gives alkene; primary alcohol oxidation gives aldehyde or acid; phenol + Br₂ water gives 2,4,6-tribromophenol; phenol + CHCl3/NaOH then acidification gives salicylaldehyde.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

1Predict the product when phenol is treated with bromine water.
2The -OH group strongly activates the ring and directs substitution to ortho and para positions, so three bromine atoms enter at 2, 4 and 6 positions, forming 2,4,6-tribromophenol.

Method you can reuse

Identify whether the compound is alcohol or phenol, locate the reactive site, note the reagent and conditions, then decide whether substitution, oxidation, dehydration or esterification occurs.

Visual tip

Reaction schemes with products at ortho and para positions help in phenol substitution questions.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

What is the major product of the Reimer-Tiemann reaction of phenol?

Think first, then show answer

Salicylaldehyde, also called o-hydroxybenzaldehyde, is the major product.

Common wrong answer

Writing benzaldehyde as the Reimer-Tiemann product of phenol.

Why it loses marks: The -OH group remains on the ring and the formyl group mainly enters the ortho position.

Don't mix this up

Students often write monobromophenol for phenol with bromine water, missing the strong activating effect of -OH in aqueous conditions.

Exam tip

Always include the reagent and condition because phenol can give different substitution products under different conditions.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Questions ask for product prediction, named reaction identification, observation, conversion, and reagent-condition matching.

1
Enough for 1 mark
Alcohols undergo reactions such as esterification, dehydration and oxidation, while phenols undergo electrophilic substitution reactions such as bromination, nitration and Reimer-Tiemann reaction.
2
Add for 2 marks
Example: Phenol with bromine water gives a white precipitate of 2,4,6-tribromophenol.
3
Add for 3 marks
Alcohol reactions are controlled by the O-H bond and the carbon bearing -OH.

MCQ Quiz

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