Alcohols, Phenols and Ethers – Important NEET Questions, Reactions & Mechanisms

The chapter Alcohols, Phenols and Ethers is one of the most scoring parts of Organic Chemistry in the NEET exam. Every year, 1–2 direct questions are asked from this chapter, mostly based on preparation methods, reaction mechanisms, acidic strength, or physical properties.

🔬 Classification and Nomenclature

Alcohols are classified as primary (1°), secondary (2°), and tertiary (3°) based on the number of alkyl groups attached to the carbon bearing the -OH group. Phenols are aromatic compounds containing a hydroxyl group directly attached to a benzene ring. Ethers are compounds with the general formula R–O–R'.

📘 General Formulas

• Alcohols: R–OH
• Phenols: Ar–OH
• Ethers: R–O–R'

🧪 Preparation of Alcohols

Alcohols can be prepared by various methods such as:

• Hydration of alkenes (acid-catalyzed addition of water)
• Reduction of aldehydes and ketones using LiAlH₄ or NaBH₄
• Hydrolysis of alkyl halides
• Grignard reagent reaction with carbonyl compounds

🧪 Reactions of Alcohols

Important reactions include:

• Dehydration: Alcohol → Alkene using conc. H₂SO₄ and heat
• Lucas Test: Differentiates primary, secondary, and tertiary alcohols using Lucas reagent (ZnCl₂ + HCl)
• Oxidation: Primary alcohol → Aldehyde → Carboxylic acid

🔬 Properties of Phenols

Phenols are weakly acidic in nature. They form phenoxide ions in the presence of NaOH. Electrophilic substitution reactions like bromination and nitration occur at ortho and para positions due to resonance.

• Reaction with bromine water: Phenol gives 2,4,6-tribromophenol (white ppt).
• Nitration: Phenol + HNO₃ → o- and p-nitrophenol
• Acidic strength: Phenol is more acidic than alcohols due to resonance stabilization of the phenoxide ion.

🧪 Preparation & Reactions of Ethers

The most common method for ether synthesis is the Williamson Synthesis:

• R–X + R'O^- → R–O–R' (SN2 mechanism)

Reactions:

• Cleavage with HI/HBr (more effective with HI)
• Forming alcohols and alkyl halides

💡 Important NEET Mechanisms to Practice

1. Dehydration of alcohols (E1 mechanism for 2° and 3° alcohols)
2. Electrophilic substitution in phenol
3. SN2 reaction in Williamson ether synthesis

❓ NEET Practice Questions

1. Which alcohol gives turbidity immediately in the Lucas test?
2. What is the product when phenol reacts with bromine water?
3. Which alcohol will undergo dehydration most easily?
4. Why is phenol more acidic than ethanol?
5. Which base is used in Williamson ether synthesis?

🧠 Tips for NEET Preparation

• Memorize classification of alcohols using examples.
• Focus on acidic strength order: Water < Alcohol < Phenol < Carboxylic Acid
• Practice name reactions like Lucas Test, Williamson Synthesis, Reimer–Tiemann Reaction.

📚 Related Posts:

• Hydrocarbons – Important NEET Questions & Mechanisms
• Aromatic Hydrocarbons – Reactions & Concepts

Conclusion: Alcohols, Phenols, and Ethers is a highly conceptual and scoring chapter for NEET Chemistry. Focus on preparation reactions, acidic strength, and mechanism-based questions. Make short notes and revise NCERT thoroughly.