Skip to main content

Amines | Class 12 Organic Chemistry | SM-Educate

Amines | Class 12 Organic Chemistry | SM-Educate
← Back to Organic Chemistry Hub
CS-991 · Module O-XII5

Amines

Class XII · Organic Chemistry
🎥 Video lesson coming soon

📋 Classification of Amines

Amines are classified by how many carbon groups are attached to the nitrogen:

  • Primary (1°): R-NH₂
  • Secondary (2°): R₂NH
  • Tertiary (3°): R₃N

⚖️ Basicity of Amines

Amines are basic due to the lone pair of electrons on nitrogen, which can accept a proton. In aqueous solution, basicity is affected by a balance of factors:

  • Inductive effect: more alkyl groups push electron density onto nitrogen, increasing basicity
  • Steric hindrance & solvation: bulkier amines are harder to solvate, which can reduce their effective basicity

These competing effects mean, in water, the typical order for simple alkyl amines is often secondary > primary > tertiary.

Aromatic amines (like aniline) are much less basic than aliphatic amines, because the lone pair on nitrogen is partly delocalized into the aromatic ring through resonance, making it less available to accept a proton.

🔄 Diazonium Salts

A primary aromatic amine reacts with nitrous acid (generated in situ from NaNO₂ + HCl) at low temperature (0-5°C) to form an aryl diazonium salt:

Ar-NH₂ + HNO₂ → Ar-N₂⁺ + 2H₂O

Diazonium salts are versatile intermediates — they're used in the Sandmeyer reaction to introduce halogens or -CN onto a ring, and in coupling reactions to produce brightly coloured azo dyes.

📝 Practice MCQs

Q1: A secondary amine has the general structure:
a) R-NH₂ b) R₂NH c) R₃N d) R-CONH₂
Show Answer
✅ b) R₂NH
Q2: Amines are basic because of:
a) Their carbon chain b) The lone pair on nitrogen c) Hydrogen bonding only d) Their molecular weight
Show Answer
✅ b) The lone pair on nitrogen
Q3: Aromatic amines like aniline are less basic than aliphatic amines because:
a) They contain more carbon b) The lone pair on nitrogen is delocalized into the ring c) They are unstable d) They lack nitrogen
Show Answer
✅ b) The lone pair on nitrogen is delocalized into the ring
Q4: Diazonium salts are formed from:
a) Tertiary amines b) Primary aromatic amines + nitrous acid c) Secondary amines + water d) Carboxylic acids
Show Answer
✅ b) Primary aromatic amines + nitrous acid
Q5: Diazonium salts are used in the Sandmeyer reaction to introduce:
a) Only oxygen b) Halogens or -CN onto a ring c) Only hydrogen d) Only nitrogen
Show Answer
✅ b) Halogens or -CN onto a ring
Subscribe to SM-Educate on YouTube for weekly organic chemistry updates.

Comments

Post a Comment

Popular posts from this blog

15 Chemistry Mistakes That Cost Students Marks in Exams (Class 9–12 & IGCSE)

Learn the 15 most common Chemistry exam mistakes and how to avoid them. Useful for Class 9, Class 10, Class 11, Class 12 and IGCSE Chemistry students. Last Updated: May 2026 Every year, thousands of students lose marks in Chemistry exams not because they don't know the concepts, but because of avoidable mistakes. Examiners frequently report errors related to units, calculations, scientific vocabulary, and question interpretation. In this article, you will learn the most common Chemistry mistakes and how to avoid them in Class 9, Class 10, Class 11, Class 12, and IGCSE Chemistry examinations. 1. Not Reading the Question Carefully Many students answer what they think the question asks instead of what is actually written. Tip: Underline important words such as: Define Explain Calculate Compare State Describe Different command words require different types of answers. 2. Forgetting Units Students often obtain the correct numerical answer but forget to write the ...
Post a Comment
Read more

The Unreasonable Reactivity of Fluorine: A Case Study in Extremes

The Unreasonable Reactivity of Fluorine | SM-EDUCATE Chemistry 🧪 SM-EDUCATE CHEMISTRY June 07, 2026 The Unreasonable Reactivity of Fluorine: A Case Study in Extremes ⚡ Dangerous chemistry · Periodic table deep dive · Fiercest nonmetal 📤 SHARE Inorganic Chemistry Fluorine Reactivity Halogens Extreme Chemistry Periodic Trends Dangerous Chemicals Fluorine is the angriest element in the periodic table. It reacts with nearly everything — including noble gases, asbestos, and even brick. It sets water on fire. It attacks gold and platinum. It chews through glass. And yet, this pale yellow gas is essential for Teflon, pharmaceuticals, and uranium enrichment. Why is fluorine so unreasonably reactive? Let's go beyond the textbook "most electronegative" and explore bond enthalpies, lattice energies, and the terrifying joy of fluorine chemi...
Post a Comment
Read more

Asymmetric Synthesis: How Chemists Outsmart Nature’s Symmetry

Asymmetric Synthesis | Outsmarting Nature’s Symmetry | SM-EDUCATE Chemistry 🧪 SM-EDUCATE CHEMISTRY June 07, 2026 Asymmetric Synthesis: How Chemists Outsmart Nature’s Symmetry 🔬 Chiral worlds · Enantioselective reactions · Drug design essentials 📤 SHARE Organic Chemistry Asymmetric Synthesis Chirality Enantioselectivity Pharmaceutical Chemistry Catalysis Nature is chiral. Your DNA, your proteins, your sugars — all exist in only one mirror‑image form. But when chemists build molecules in the lab, they often get a 50:50 mix of left‑ and right‑handed versions: a racemic mixture . For many drugs, one enantiomer cures, the other kills. How do we outsmart nature’s symmetry? Asymmetric synthesis — the art of creating single enantiomers on demand. Left hand Right hand Enantiomers: mirror image...
Post a Comment
Read more