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CBSE Class 12 · Chemistry

Amines

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 “Amines” 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

1Structure of Amines

Structure of amines: N with a lone pair as taught; pyramidal. An amine is a nitrogen-look, not an amide (that has C=O). CH3NH2 is the school case.

An amide labelled amine because both have N is a miss.

Figure. An amine is nitrogen with three attachments and one leftover lone pair. The lone pair is why the family is basic. Topology only — not a 3-D pyramid.

How it works

  1. Name N plus a lone pairThe structure.
  2. Keep pyramidal as the shapeThe look.
  3. Refuse a C=O-on-N as this headingThat is amide.

2Classification

Classification: 1°, 2°, 3° by how many carbons sit on N as taught; 4° ammonium if named. A class is a count-on-N, not a smell. (CH3)2NH is 2°.

Using the alcohol 1°/2°/3° rule (carbons on the C–OH) on an amine is a steal.

Figure. Count alkyl groups on N. 1°, 2° and 3° are amines. A fourth alkyl makes R₄N⁺, an ammonium salt, not an amine.

How it works

  1. Count carbons on NThe classify.
  2. Name 1°, 2°, or 3°The class.
  3. Refuse the alcohol-count as this testCount on N.

3Nomenclature

Nomenclature: -amine as taught, or the amino-prefix. Ethanamine, N-methylaniline as cases if listed. A name is a rule-output, not a brand.

Numbering so NH2 sits high is a miss.

Figure. IUPAC: the parent is the longest carbon chain; N- locants name extra alkyls on nitrogen. Same nitrogen, three different names.

How it works

  1. Find the chain and the NThe given.
  2. Write the taught -amine nameThe name.
  3. Keep N-locants if a 2°/3° was named that wayHonest.

4Preparation of Amines

Preparation: from haloalkanes (ammonia as taught), reduction of nitro if listed. Preparation is a from-what. One school route is enough.

A carboxyl as the default amine-start is a miss.

Figure. Three school routes to a 1° amine: reduce a nitro compound; Hoffmann on an amide (one carbon is lost); Gabriel from phthalimide (1° aliphatic only).

How it works

  1. Name the starting lookThe from.
  2. Name the taught reagentThe route.
  3. Keep the product as an amineThis heading.

5Physical Properties

Physical properties: boiling (H-bond for 1°/2° as taught) and mix. Physical is a look, not a basicity-mechanism. One H-bond-versus-3° mention is enough.

A 3° with two H-bonds as the default is a miss — it has no H on N.

Figure. Same formula C₃H₉N: n-propylamine 49 °C, N-methylethanamine 37 °C, trimethylamine 3 °C. More N–H bonds means more hydrogen bonding and a higher boiling point. 3° has no N–H.

How it works

  1. Name bp or mix as taughtThe property.
  2. Keep H-bond on 1°/2° if taughtThe why.
  3. Refuse a mechanism herePhysical.

6Chemical Reactions

Chemical reactions: basicity (lone pair) as taught; acylation; carbylamine if named for 1°. Reaction is who-uses-the-lone-pair, not a boil. One basicity-compare is enough.

Calling every amine equally basic with no structure-talk is a skip if the lesson ranked them.

Figure. Hinsberg test with benzenesulfonyl chloride, then alkali. 1° gives a salt that dissolves; 2° gives a solid that does not; 3° does not react and is recovered.

How it works

  1. Name the lone-pair jobBasicity or the named reaction.
  2. Keep 1° as the carbylamine case if taughtThe extra.
  3. Refuse a physical bp as this headingChemistry.

7Method of Preparation of Diazonium Salts

Diazonium preparation: ArNH2 plus the taught nitrite-look in cold acid as framed. A diazonium is an Ar–N2+ school ion, not an alkyl leftover (those sit unstable as taught). One aniline-case is enough.

A warm leftover as the default prep is a miss if the lesson said cold.

Figure. Aniline plus NaNO₂/HCl at 0–5 °C gives the diazonium salt. If the bath warms, the salt hydrolyses to phenol and nitrogen — the exam trap.

How it works

  1. Name aniline (or ArNH2) and the taught nitrite-lookThe from.
  2. Keep it cold as framedThe caution.
  3. Refuse an alkyl-amine as the stable caseAryl.

8Importance of Diazonium Salts in Synthesis of

Importance of diazonium in synthesis: a replace-N2 look as taught — halo, CN, OH, or a coupling if named. Diazonium is a stepping-stone, not a final brand. One replacement-sentence is enough.

A how-to dye-works as the whole heading is the wrong size.

Figure. The diazonium group is a leaving group. School replacements: CuCl → Ar–Cl, CuCN → Ar–CN, warm water → Ar–OH, hypophosphorous acid → Ar–H.

How it works

  1. Name N2 leaving and a taught replacementThe use.
  2. Keep one coupling or halo if listedThe extra.
  3. Refuse a factory-manualThis class.
Amine class counts carbons on
  1. Nitrogen as taught
  2. The next carbon only, like alcohols
  3. Oxygen

Count on N.

Notes

  • Mapped to the official NCERT chapter “Amines”. 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

  • 1°/2°/3° amine: carbons on N
  • diazonium: Ar–N2+ as taught

Recap

Hold these pegs from the official chapter “Amines”. The wording is ExamMaster’s teaching, not a textbook recap.

Structure of Amines
Structure of amines: N with a lone pair as taught; pyramidal.
Classification
Classification: 1°, 2°, 3° by how many carbons sit on N as taught; 4° ammonium if named.
Nomenclature
Nomenclature: -amine as taught, or the amino-prefix.
Preparation of Amines
Preparation: from haloalkanes (ammonia as taught), reduction of nitro if listed.
Physical Properties
Physical properties: boiling (H-bond for 1°/2° as taught) and mix.
Chemical Reactions
Chemical reactions: basicity (lone pair) as taught; acylation; carbylamine if named for 1°.

Practise Amines

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  • 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
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