CBSE Class 12 · Chemistry
Alcohols, Phenols and Ethers
Official NCERT chapter from Chemistry Part I–II (book code lech1). ExamMaster notes are original teaching at CBSE Class 12 depth.
This lesson follows the official chapter “Alcohols, Phenols and Ethers” in Chemistry Part I–II. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.
- CBSE Class 12
- Medium level
- 8 concepts
1Classification
Classification: alcohols (1°, 2°, 3° as taught), phenols (OH on a ring), ethers (R–O–R). A class is an O-look, not a smell. CH3CH2OH is a 1° alcohol; PhOH is a phenol.
Calling phenol an alcohol because both have OH is a miss if the lesson split them.
Figure. The chapter splits oxygen compounds by what the oxygen is joined to. Alcohols then split by how many carbons sit on the OH carbon.
How it works
- Look at what holds the OThe classify.
- Name alcohol / phenol / etherThe class.
- Split 1°/2°/3° only for alcohols as taughtThe extra.
2Nomenclature
Nomenclature: -ol for alcohols, phenol as the parent if taught, alkoxy for ethers. Ethanol, methoxyethane as cases. A name is a rule-output, not a brand.
Numbering so OH sits high is a miss.
Figure. Name the longest carbon chain first, give the OH carbon the lowest locant, then write the -ol name. The locant is the step that separates propan-1-ol from propan-2-ol.
How it works
- Find the chain and the OH or OThe given.
- Add the taught suffix or the alkoxy writeThe name.
- Keep the lowest locantThe rule.
3Structures of Functional Groups
Structures of functional groups: C–OH, Ar–OH, C–O–C as taught — shapes and a polarity-look. A group is a drawn bit, not a smell. One tetrahedral C–OH is enough.
A carbonyl labelled alcohol because both have O is a miss.
Figure. The functional group is the attachment, not a pretty drawing. Alcohol is OH on an alkyl carbon, phenol is OH on an aryl carbon, ether is oxygen between two carbons.
How it works
- Draw the taught groupThe structure.
- Keep alcohol ≠ phenol ≠ ether as three drawsThe split.
- Refuse a carbonyl as this headingA different group.
4Alcohols and Phenols
Alcohols and phenols: acidity (phenol more acidic as taught), reactions (Na, ester, electrophilic on phenol if listed). This heading is the pair’s chemistry, not the ether yet. One acidity-compare is enough.
Calling ethanol more acidic than phenol as the default is a miss if the lesson said the reverse.
Figure. Aqueous NaOH is the school test that separates the two. Phenol gives a salt; a simple alcohol does not. The boxes name the test, not a mechanism arrow.
How it works
- Compare alcohol vs phenol acidity as taughtThe pair.
- Name one school reactionThe chemistry.
- Keep ethers for their headingA later word.
5Some Commercially Important Alcohols
Commercially important alcohols: methanol, ethanol as taught — a named make or use, school-size. Commercial is a use-column, not a distillery-manual.
A how-to brew as the whole heading is the wrong size.
Figure. The three commercial names are kept by a use, not by a reaction list. Methanol is the solvent, ethanol the spirit, glycerol the soap ingredient.
How it works
- Name methanol or ethanolThe case.
- Attach a taught make or useThe sentence.
- Refuse a how-toThis class.
6Ethers
Ethers: R–O–R, a weak polarity, cleavage if taught (HX). Ether is the C–O–C family, not an alcohol isomer-dump unless named (metamerism). One diethyl ether mention is enough.
An alcohol labelled ether because both have O is a miss.
Figure. C2H6O is one formula and two families. The alcohol has C–OH; the ether has C–O–C. Naming the attachment is how you tell them apart.
How it works
- Name C–O–CThe ether.
- Keep a taught reaction (cleavage) if askedThe chemistry.
- Refuse OH as this headingDifferent group.
7A definition is a test you can run
Alcohol-word is a test: 1°/2°/3°, a phenol-split, or an ether. If you only say “OH”, you have a heading.
A bottle-sticker is not the test.
Figure. A class name is a test you run on the oxygen. Alkyl C–OH is an alcohol, aryl C–OH is a phenol, and C–O–C is an ether.
How it works
- Name the carbon-look or the C–O–CThe object.
- Give the school sentenceThe test.
- Then the word has contentThe definition ran.
8Name the given before the unknown
The given is a formula. The unknown is the class. Copy PhOH before you treat it as ethanol.
Using 1°/2°/3° on a phenol as if it were an alkyl alcohol is a silent swap.
Figure. Write the given formula first. The unknown is the class and the IUPAC name. Here the given is CH3CH(OH)CH3, so the class is 2° and the name is propan-2-ol.
How it works
- Copy the formulaThe given.
- Name alcohol / phenol / etherThe unknown.
- Then classifyGiven first.
Phenol is
- OH on a ring — not a 1° alcohol
- Ethanol
- An ether always
The ring-OH.
Notes
- Mapped to the official NCERT chapter “Alcohols, Phenols and Ethers”. Original teaching only — no textbook sentences.
- Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.
Formulas
- alcohol: C–OH
- phenol: Ar–OH
- ether: C–O–C
Recap
Hold these pegs from the official chapter “Alcohols, Phenols and Ethers”. The wording is ExamMaster’s teaching, not a textbook recap.
- Classification
- Classification: alcohols (1°, 2°, 3° as taught), phenols (OH on a ring), ethers (R–O–R).
- Nomenclature
- Nomenclature: -ol for alcohols, phenol as the parent if taught, alkoxy for ethers.
- Structures of Functional Groups
- Structures of functional groups: C–OH, Ar–OH, C–O–C as taught — shapes and a polarity-look.
- Alcohols and Phenols
- Alcohols and phenols: acidity (phenol more acidic as taught), reactions (Na, ester, electrophilic on phenol if listed).
- Some Commercially Important Alcohols
- Commercially important alcohols: methanol, ethanol as taught — a named make or use, school-size.
- Ethers
- Ethers: R–O–R, a weak polarity, cleavage if taught (HX).
Practise Alcohols, Phenols and Ethers
Reading is free and needs no account. Practice, mocks and progress live in the app.
- A 4-question practice set that ends the chapter
- 1 quick check with worked explanations
- Timed mocks scored with the real marking scheme
- Readiness tracked per topic, kept on your device