Definitions [1]
Definition: Esterification
Alcohols and phenols form esters by reaction with carboxylic acid, acid halides and acid anhydrides. This reaction is called esterification.
Key Points
Key Points: Alcohols, Phenols and Ethers
- Alcohols and phenols both contain —OH group but differ in the type of hydrocarbon — aliphatic vs aromatic.
- Ethers have the general formula R—O—R, where oxygen bridges two carbon groups.
Types of Alcohols
| Type | Meaning | Position of —OH |
|---|---|---|
| Allylic Alcohol | —OH attached to sp³-hybridised carbon next to C=C double bond | Carbon next to C=C |
| Benzylic Alcohol | —OH attached to sp³-hybridised carbon next to aromatic ring | Benzylic carbon |
| Vinylic Alcohol | —OH attached directly to a vinylic carbon (CH₂=CH—) or aryl carbon | On C=C bond |
Key Points: Chemical Properties of Alcohols and Phenols
- Litmus Test — Aqueous alcohols are neutral to litmus, while aqueous phenols turn blue litmus red, confirming the acidic character of phenols.
- Reaction with Bases — Phenols react with NaOH to form water-soluble sodium phenoxide (regenerated on acidification with HCl) but do not react with NaHCO₃, since phenol is a weak acid.
- Esterification — Alcohols/phenols react with carboxylic acids (conc. H₂SO₄ catalyst), acid anhydrides (H⁺ catalyst), or acid chlorides (in pyridine) to form esters; Aspirin is the acetyl derivative of salicylic acid formed using acetic anhydride.
- Reactivity with Hydrogen Halides — Order of alcohol reactivity: 3° > 2° > 1°; order of HX reactivity: HI > HBr > HCl (HCl needs anhydrous ZnCl₂ catalyst).
- Oxidation of Alcohols — 1° alcohol → aldehyde (with PCC, best reagent) → further to carboxylic acid (with KMnO₄/K₂Cr₂O₇/HNO₃); 2° alcohol → ketone (with CrO₃); 3° alcohols resist oxidation and break C–C bonds only at high temperature.
Concepts [19]
- Classification of Alcohols and Phenols
- Classification of Ethers
- Alcohols, Phenols and Ethers
- Nomenclature
- Structures of Functional Groups of Alcohols, Phenols and Ethers
- Methods of Preparation of Alcohols
- Methods of Preparation of Phenols
- Chemical Properties of Alcohols and Phenols
- Chemical Reactions of Alcohols and Phenols
- Reactions Involving Cleavage of O-H Bond
- Reactions Involving Cleavage of Carbon–Oxygen (C–O) Bond in Alcohols
- Chemical Properties of Phenol
- Preparation of Commercially Important Alcohols
- Uses of Phenols
- Preparation of Ethers
- Physical Properties of Ethers
- Chemical Reaction of Ethers - Cleavege of C-O Bonds
- Chemical Reaction of Ethers - Electrophilic Substitution
- Uses of Ethers
