Alcohols, Phenols and Ethers – JEE Mains Chemistry

• by Zenith LMS
• Updated April 2025

1. Introduction

This chapter deals with the structure, nomenclature, properties, and reactions of alcohols, phenols, and ethers — important functional groups in organic chemistry.

2. Classification

• Alcohols: Classified as primary (1°), secondary (2°), and tertiary (3°) based on the number of alkyl groups attached to the carbon with –OH.
• Phenols: Hydroxy derivatives of benzene (–OH directly attached to aromatic ring).
• Ethers: Compounds with the structure R–O–R", where R and R" are alkyl or aryl groups.

3. Nomenclature

• Alcohols: Named by replacing –e of alkane with –ol (e.g., Ethanol)
• Phenols: Use 'phenol' as parent compound, name substituents accordingly
• Ethers: Common names use alkyl groups alphabetically + 'ether' (e.g., ethyl methyl ether)

4. Preparation Methods

• Alcohols: Hydration of alkenes, hydrolysis of alkyl halides, fermentation
• Phenols: From cumene, benzene sulfonic acid, diazonium salts
• Ethers: Williamson ether synthesis (R–X + R"O⁻ → R–O–R")

5. Physical Properties

• Hydrogen bonding in alcohols and phenols → higher boiling points
• Ethers have lower boiling points, are volatile and less soluble in water

6. Chemical Reactions

• Alcohols: Oxidation, dehydration to alkenes, esterification
• Phenols: Electrophilic substitution (nitration, halogenation), reactions with metals
• Ethers: Cleavage by strong acids like HI, HBr

7. Tests and Identification

• Lucas Test: Differentiates 1°, 2°, and 3° alcohols
• Ferric Chloride Test: Violet color indicates presence of phenol
• Iodoform Test: Positive for ethanol and methyl ketones

8. Uses and Applications

• Alcohols: Solvents, antiseptics (ethanol), fuel (methanol)
• Phenols: Antiseptics (Dettol), manufacturing of plastics
• Ethers: Solvents in labs, anesthetics (diethyl ether)