Alcohols, Phenols and Ethers

part 1

Alcohols — Preparation and Properties

• Classification and nomenclature
• Preparation of alcohols
• Physical properties of alcohols
• Chemical reactions — dehydration, oxidation
• Reactions with HX, PX₃, SOCl₂

part 2

Phenols

• Preparation of phenols
• Physical and chemical properties of phenols
• Acidity of phenols
• Electrophilic aromatic substitution in phenols
• Uses of phenols

part 3

Ethers

• Preparation of ethers — Williamson synthesis
• Physical properties of ethers
• Chemical reactions of ethers
• Uses of ethers
• Important reactions — distinction tests

Lucas test (1°, 2°, 3° alcohols)

3° → immediate turbidity; 2° → turbid in 5 min; 1° → no reaction (cold)

★ board favourite

H-bonding in alcohols (high bp vs ethers)

O−H···O bonding; intermolecular; raises bp

★ frequently asked

Resonance of phenol

−OH lone pair delocalises into ring; ring activated; acidic

★ frequently asked

Acid catalysed dehydration order

3° > 2° > 1° (stability of carbocation)

★ frequently asked

Victor Meyer test

1° → red; 2° → blue; 3° → colourless

★ frequently asked

Kolbe's reaction (phenol + CO₂)

Phenol + NaOH → sodium phenoxide + CO₂ → salicylate

★ frequently asked

Riemer-Tiemann reaction

Phenol + CHCl₃ + NaOH → o-hydroxybenzaldehyde

★ frequently asked

Williamson synthesis (preparation of ethers)

R−ONa + R'−X → R−O−R' + NaX

★ frequently asked

Write the products and name the reactions when phenol is treated with: (i) conc. HNO₃, (ii) CHCl₃ and aqueous NaOH, (iii) CO₂ and NaOH followed by acidification.

How would you distinguish between (i) phenol and ethanol, and (ii) a primary and a tertiary alcohol using a chemical test?

How is phenol prepared from cumene? Write the chemical equations involved.

How are alcohols prepared by (i) hydroboration–oxidation of alkenes, and (ii) reduction of aldehydes/ketones? Write the reactions with suitable examples.

Explain the following: (i) Phenol is more acidic than ethanol. (ii) o-Nitrophenol is more volatile than p-nitrophenol. (iii) Boiling points of alcohols are higher than those of corresponding haloalkanes.

(a) Write the mechanism of the acid-catalysed dehydration of ethanol to give ethene. (b) Arrange the following in increasing order of their acidic strength and justify: ethanol, phenol, o-cresol, p-nitrophenol.

Why is o-nitrophenol more acidic than o-methoxyphenol?

(a) Explain Williamson's ether synthesis with a suitable example. Why are primary alkyl halides preferred for it? (b) What happens when anisole is treated with HI? Write the reaction.

What happens when: (i) ethoxybenzene is treated with HBr, (ii) phenol is treated with bromine water, (iii) ethanol is heated with conc. H₂SO₄ at 413 K? Write the reactions.

What is Kolbe's reaction? Write the reaction and name the product formed from sodium phenoxide.

Why do alcohols have higher boiling points than ethers of comparable molecular mass?

How many marks is Alcohols, Phenols and Ethers worth in the Class 12 board exam?

Around 6 marks of the 70-mark CBSE Chemistry theory paper, based on the official unit-wise weightage. Acidity order of phenols and reactions are common.

Is Alcohols, Phenols and Ethers easy or hard?

It's rated hard — one of the tougher chapters in Class 12 Chemistry. Most students need about 4 hours to cover it well.

What are the important topics in Alcohols, Phenols and Ethers?

The chapter covers 13 NCERT topics in 3 areas: Alcohols — Preparation and Properties; Phenols; Ethers.

What questions come from Alcohols, Phenols and Ethers in board exams?

Between 2018–2024, CBSE board papers asked questions from this chapter on Reactions of Phenol, Distinguishing Tests, Preparation of Phenol, Preparation of Alcohols — 1- to 5-mark questions.