Alcohols, Phenols, and Ethers Summary for JEE 2025

Study Notes

This lecture covers reactions and preparations of alcohols, phenols, and ethers, focused on JEE 2025 syllabus.

Oxidation: Alcohols can be oxidized to aldehydes, ketones, or carboxylic acids using reagents like KMnO₄, K₂Cr₂O₇, Jones reagent, PCC, PDC, and CrO₃/Acetone. The specific outcome depends on the type of alcohol (primary, secondary, tertiary) and the oxidizing agent.
Dehydration: Alcohols can be dehydrated to alkenes using concentrated sulfuric acid (H₂SO₄) at high temperatures. This process involves removing a water molecule.
Esterification: Alcohols can react with carboxylic acids to form esters in the presence of acid catalysts (e.g., H⁺).

Nitration: Phenol can be nitrated using a mixture of concentrated sulfuric acid (H₂SO₄) and nitric acid (HNO₃) to form nitrophenols.
Halogenation: Halogenation may happen via electrophilic aromatic substitution. Bromine (Br₂) or chlorine (Cl₂) will react in a certain controlled environment to add halogens in the presence of Lewis Acid.
Reimer-Tiemann Reaction: Reaction with chloroform (CHCl₃) and a base (NaOH) to introduce a formyl group (CHO).
Kolbe's reaction: Reaction of a phenoxide ion with carbon dioxide (CO₂)

Cleavage: Ethers can be cleaved using strong acids (e.g., HI, HBr) or H₂O₂ with certain metal ions to produce alcohols or alkyl halides.

Reduction of Aldehydes and Ketones: Aldehydes and ketones can be reduced to alcohols using reagents like LiAlH₄, NaBH₄, or DIBAL-H.
Grignard Reagents: Grignard reagents (RMgX) can be used to form alcohol in reaction with aldehydes and ketones.
- Alkyl halides react with Mg in an ether to form Grignard reagents. These will then react with a variety of carbonyl compounds (aldehydes or ketones) to form alcohol that can be hydrolyzed to form the desired alcohol intermediate.
- Reactions with formaldehydes lead to primary alcohol
- Reactions with ketones lead to secondary alcohol

Williamson Ether Synthesis: Alkyl halides react with sodium alkoxides (RONa) in dry conditions to produce ethers.

Dow's process: Chlorobenzene is treated with NaOH/CO₂ to produce phenol.
Cumene process: Cumene reacts with oxygen (O₂) and then is treated with water (H₂O) then acid to produce phenol.

Many are possible, including reduction of alkyl halides, aldehydes, ketones, etc. Different methods may result in distinct alcohols (by primary, secondary, or tertiary classifications).