Alcohols, Ethers, Phenols & Related Reagents – Core Vocabulary

This set defines the essential vocabulary, reagents, mechanisms and characteristic reactions of alcohols, ethers, phenols, epoxides and common organic reductions/oxidations relevant to JEE (Main + Advanced) Organic Chemistry.

Monohydric Alcohol

An alcohol containing exactly one –OH group bonded to an sp³-hybridised carbon.

Dihydric Alcohol (Glycol)

An alcohol that possesses two hydroxyl (–OH) groups in the molecule.

Trihydric Alcohol

An alcohol containing three hydroxyl groups; e.g., glycerol.

Polyhydric Alcohol

A compound with four or more –OH groups attached to different carbons.

Primary (1°) Alcohol

An alcohol in which the carbon bearing –OH is attached to only one other carbon.

Secondary (2°) Alcohol

An alcohol whose –OH-bearing carbon is bonded to two other carbons.

Tertiary (3°) Alcohol

An alcohol where the carbon carrying –OH is connected to three other carbons.

Bent Structure of Alcohol

Alcohol molecules adopt a bent geometry with C–O–H bond angle ≈108.5° due to sp³-hybridised O containing two lone pairs.

Hydroboration–Oxidation

Anti-Markovnikov hydration of alkenes using BH₃ followed by H₂O₂/⁻OH to give 1° alcohols.

Oxymercuration–Demercuration

Markovnikov hydration of alkenes via Hg(OAc)₂/H₂O then NaBH₄, producing alcohols without rearrangement.

Hydration of Alkene

Addition of H₂O across C=C (acid-catalysed) to form alcohol.

Grignard Reagent

Organomagnesium halide (RMgX) that adds to carbonyls; after hydrolysis gives 1°, 2°, or 3° alcohols depending on the substrate.

Lucas Reagent

Conc. HCl + anhydrous ZnCl₂; distinguishes 1°, 2°, 3° alcohols by turbidity rate.

Victor-Meyer Test

Colour test (red-blue-none) used to classify primary, secondary and tertiary alcohols via nitrolic/isonitroso derivatives.

Dichromate Test

Oxidation with K₂Cr₂O₇/H⁺; 1° and 2° alcohols turn green (Cr³⁺), 3° do not.

Pinacol–Pinacolone Rearrangement

Acid-induced dehydration of a vicinal diol (pinacol) to a pinacolone ketone via carbocation rearrangement.

Williamson Ether Synthesis

SN2 reaction between alkoxide ion and primary alkyl halide yielding R–O–R’ ethers.

Symmetrical (Simple) Ether

Ether where both alkyl groups are identical (R–O–R).

Unsymmetrical (Mixed) Ether

Ether possessing two different alkyl/aryl groups (R–O–R’).

Ether Peroxide Formation

Autoxidation of ethers in air forming explosive hydroperoxides/ peroxides; avoided by storing over Na/K wires.

Oxonium Ion

Protonated ether/alcohol (R₂OH⁺) formed when ethers react with strong acids like H₃O⁺, HX.

Cleavage of Ether with HI

HI converts R–O–R’ to RI + R’OH (or R’I) via SN1 or SN2 depending on alkyl stability; excess HI gives two alkyl iodides.

Dow Process

Industrial synthesis of phenol by NaOH (300 °C, 300 atm) on chlorobenzene forming sodium phenoxide then acidifying.

Cumene Process

Manufacture of phenol & acetone via oxidation of cumene to cumene hydroperoxide followed by acid cleavage.

Kolbe Reaction

Electrolytic or base-promoted carboxylation of phenoxide with CO₂ giving salicylic acid (o-hydroxybenzoic acid).

Reimer–Tiemann Reaction

Formylation of phenols using chloroform/NaOH to yield ortho-hydroxybenzaldehydes; with CSCl₂ gives salicylic acid.

Fries Rearrangement

Lewis-acid-catalysed migration of acyl group in phenyl ester producing o- and p-hydroxyaryl ketones.

Schotten–Baumann Benzoylation

Base-catalysed acylation of alcohols/phenols with benzoyl chloride yielding benzoate esters.

Acidic Nature of Alcohols

Order: H₂O > 1° > 2° > 3° alcohols; all weaker acids than water but react with Na/K to evolve H₂.

Lucas Reactivity Order

Rate with HCl/ZnCl₂: 3° > 2° > 1° alcohol.

Hydrogenation of Carbonyls

Reduction of aldehydes/ketones to alcohols using H₂/Pd, Pt or Ni.

Bouveault–Blanc Reduction

Conversion of esters to primary alcohols via Na/ethanol (metal-alcohol system).

Stephen Reduction

Partial reduction of nitriles to aldehydes with SnCl₂/HCl followed by hydrolysis.

LiAlH₄ (LAH)

Powerful hydride reducer; converts carbonyl derivatives, acids, esters, nitriles, nitro compounds to alcohols/amines.

NaBH₄

Milder hydride reagent; reduces aldehydes, ketones and acid chlorides to corresponding alcohols in protic solvents.

DiBAL-H

Di-isobutylaluminium hydride; at −78 °C reduces esters/nitriles selectively to aldehydes.

Lindlar Catalyst

Pd/CaCO₃ poisoned with quinoline; hydrogenates alkynes to cis-alkenes (syn addition).

Birch Reduction

Na/NH₃(l) (with ROH) converts alkynes to trans-alkenes and partially reduces aromatic rings to 1,4-cyclohexadienes.

Rosenmund Reduction

H₂ over Pd/BaSO₄ (poisoned) selectively reduces acid chlorides to aldehydes.

Meerwein–Ponndorf–Verley Reduction

Al(O-i-Pr)₃ in isopropanol reduces ketones to alcohols via hydride transfer; reversible of Oppenauer oxidation.

Oppenaeur Oxidation

Al(O-t-Bu)₃ with acetone oxidises secondary alcohols to ketones while reducing acetone to isopropanol.

Baeyer Reagent

Dilute, cold alkaline KMnO₄; oxidises alkenes to cis-vicinal diols and alkynes to diketones.

OsO₄ Oxidation

Osmium tetroxide/NaHSO₃ converts alkenes to syn-glycols with high stereospecificity.

Peroxyacid Epoxidation

MCPBA or peracetic acid forms epoxides from alkenes; subsequent hydrolysis gives anti-diols.

Baeyer–Villiger Oxidation

Peracid insertion next to carbonyl converts ketones to esters and cyclic ketones to lactones.

Periodic Acid (HIO₄) Cleavage

Selective oxidative cleavage of vicinal diols, α-hydroxy carbonyls to carbonyl fragments via cyclic periodate ester.

Pinacol

1,2-dihydroxy-2,3-dimethylbutane, undergoes acid-induced rearrangement to pinacolone.

Ether as Solvent

Anhydrous diethyl ether stabilises Grignard reagents via coordination to Mg and provides moisture-free medium.

Epoxide (Oxirane)

Three-membered cyclic ether formed by alkene epoxidation or intramolecular ring closure of halohydrins.

Ring Opening of Epoxide

SN2-type nucleophilic attack at less hindered carbon under basic conditions; acid opens via protonated epoxide.

Lucas Turbidity Time

1° → no cloud at RT; 2° → cloudy in ≈5 min; 3° → immediate cloudiness, indicating relative carbocation stability.

Phenol

Hydroxybenzene; weakly acidic aromatic compound able to form phenoxide ion and undergo electrophilic substitution.

Ferric Chloride Test

Phenols give coloured complexes (often violet) with Fe³⁺ due to phenoxide formation.

Libermann’s Test

Phenol + NaNO₂ + conc. H₂SO₄ yields deep red/blue coloration on basification, confirming phenolic –OH.

Kolbe–Schmitt Reaction

CO₂ under pressure with sodium phenoxide produces salicylic acid (ortho-hydroxybenzoic acid).

Dow Phenol Process

High-temperature NaOH hydrolysis of chlorobenzene to sodium phenoxide followed by acidification to phenol.

Cumene Hydroperoxide

Intermediate in cumene process; acid cleavage affords phenol and co-product acetone.

Fries Rearrangement Products

Ortho- and para-hydroxy aryl ketones obtained from phenyl esters under AlCl₃ or HF catalysis.

Benzyl Protection as Benzyl Ether

ROH + PhCH₂Cl (base) gives benzyl ether, removable by hydrogenolysis (H₂/Pd) regenerating alcohol.

Peroxide Test for Ether

Fe²⁺/KSCN with suspected ether; red Fe(SCN)³⁺ colour indicates presence of peroxides.