Key Fact
Amines classification
Primary (1°): R-NH₂. Secondary (2°): R₂NH. Tertiary (3°): R₃N. Aliphatic vs aromatic. Quaternary ammonium salt: R₄N⁺X⁻.
-- NCERT Class 12 Chemistry, Ch. 9, p. 260Amines Nomenclature
8 MCQs9-step worked example
Source: NCERT AminesOfficial key: NTA-verifiedLast updated: 24 Sep 2026
Amines Nomenclature, explained for NEET
The trap that costs marks here: confusing Hofmann elimination product selectivity with Saytzeff (Zaitsev) selectivity. When you see a quaternary ammonium hydroxide undergoing elimination, the product is the least substituted alkene — the opposite of what you'd pick for an alkyl halide with a base.
Nomenclature and classification of amines
Amines are derivatives of ammonia where one, two, or three hydrogen atoms are replaced by alkyl or aryl groups (NCERT Class 12 Chemistry Chapter 9, page 260).
Classification:
- Primary (1°): One H replaced — R–NH₂ (e.g., methylamine, CH₃NH₂)
- Secondary (2°): Two H replaced — R₂NH (e.g., dimethylamine, (CH₃)₂NH)
- Tertiary (3°): Three H replaced — R₃N (e.g., trimethylamine, (CH₃)₃N)
IUPAC naming rules:
- Identify the longest chain containing –NH₂ as the parent.
- Replace terminal "-e" with "-amine" (methanamine, ethanamine, propan-1-amine).
- For secondary/tertiary amines, the largest alkyl group is the parent chain; smaller groups carry the prefix "N-" (e.g., N-methylethanamine, N,N-dimethylmethanamine).
- When –NH₂ is a substituent on a ring or higher-priority chain, use "amino-" prefix (e.g., 3-aminopentane).
Common name system: alkyl group names + "amine" as one word (methylamine, diethylamine, triphenylamine).
Hofmann elimination — the nomenclature-adjacent reaction trap: Quaternary ammonium hydroxide (R₄N⁺OH⁻) heated → eliminates to form the least substituted alkene (Hofmann product). This is anti-Saytzeff. The bulky leaving group (NR₃) and base attack the less hindered β-hydrogen. Confusing this with standard E2 of alkyl halides (Saytzeff → most substituted alkene) is the high-frequency trap for this topic.
Can you answer these Amines Nomenclature MCQs?
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
MCQ 1Easy RecallPractice
Which of the following is a tertiary amine?
Show answer and why every option is right or wrong
Answer: C. C is correct. (CH₃)₃N has all three hydrogens of NH₃ replaced by methyl groups, making it a tertiary amine (NCERT Class 12 Chemistry Chapter 9, page 260).
Why A is wrong: A is wrong — CH₃NH₂ has only one H replaced (primary amine).
Why B is wrong: B is wrong — (CH₃)₂NH has two H replaced (secondary amine).
Why D is wrong: D is wrong — CH₃CH₂OH is an alcohol, not an amine. It contains –OH, not –NH₂.
MCQ 2Easy RecallPractice
The IUPAC name of (CH₃)₂CHNH₂ is:
Show answer and why every option is right or wrong
Answer: D. D is correct. The parent is propane; the –NH₂ is on carbon 2. Replace terminal "-e" with "-amine" → propan-2-amine. "Isopropylamine" is the common name; "2-aminopropane" uses the substituent prefix convention, not the principal characteristic group naming that IUPAC recommends for simple amines (NCERT Class 12 Chemistry Chapter 9, page 260).
Why A is wrong: A is wrong — 'isopropylamine' is the common name, not IUPAC.
Why B is wrong: B is wrong — '2-aminopropane' uses the amino-as-prefix style, which is not the preferred IUPAC name when –NH₂ is the principal functional group.
Why C is wrong: C is wrong — N-methylethanamine is CH₃NHCH₂CH₃ (a secondary amine with different structure).
MCQ 3Easy RecallPractice
The IUPAC name of CH₃–NH–C₂H₅ is:
Show answer and why every option is right or wrong
Answer: D. D is correct. The larger alkyl group (ethyl, C₂H₅) is the parent chain → ethanamine. The smaller alkyl group (methyl) on nitrogen takes the "N-" prefix → N-methylethanamine (NCERT Class 12 Chemistry Chapter 9, page 260).
Why A is wrong: A is wrong — 'ethylmethylamine' is a common name, not IUPAC.
Why B is wrong: B is wrong — 'methylethylamine' is a common name written in non-standard order.
Why C is wrong: C is wrong — 'N-ethylmethanamine' incorrectly treats the smaller group (CH₃) as parent. IUPAC uses the longest chain attached to N as parent.
MCQ 4Direct ApplicationPractice
Hofmann elimination of N,N,N-trimethylbutan-2-aminium hydroxide gives predominantly:
Show answer and why every option is right or wrong
Answer: A. A is correct. Hofmann elimination from quaternary ammonium hydroxides favours the least substituted alkene (anti-Saytzeff). The bulky –N(CH₃)₃ leaving group directs elimination toward the less hindered β-hydrogen, giving but-1-ene (NCERT Class 12 Chemistry Chapter 9; trap: Hofmann vs Saytzeff reversal).
Why B is wrong: B is wrong — but-2-ene is the Saytzeff (more substituted) product. That would form from E2 of an alkyl halide, not Hofmann elimination of a quaternary ammonium salt (trap: Hofmann–Saytzeff reversal).
Why C is wrong: C is wrong — 2-methylpropene requires a different carbon skeleton (isobutyl). The substrate is a straight-chain butan-2-yl system.
Why D is wrong: D is wrong — butane would result from reduction, not elimination. No C=C double bond forms in reduction.
MCQ 5Direct ApplicationPractice
Which compound is named N,N-diethylethanamine?
Show answer and why every option is right or wrong
Answer: A. A is correct. The parent chain is ethanamine (C₂H₅–NH₂). Two additional ethyl groups on nitrogen → N,N-diethylethanamine. This is triethylamine, (C₂H₅)₃N (NCERT Class 12 Chemistry Chapter 9, page 260).
Why B is wrong: B is wrong — (C₂H₅)₂NH is N-ethylethanamine (a secondary amine with only one N-substituent prefix).
Why C is wrong: C is wrong — C₂H₅NH₂ is simply ethanamine (a primary amine with no N-substituents).
Why D is wrong: D is wrong — (CH₃)₃N is N,N-dimethylmethanamine (trimethylamine). All groups are methyl, not ethyl.
MCQ 6Direct ApplicationPractice
An amine has the structure: C₆H₅–NH–CH₃. Naming it from the systematic parent hydride (that is, not using the retained name "aniline"), its IUPAC name is:
Show answer and why every option is right or wrong
Answer: B. B is correct. When one substituent is an aryl group attached directly to nitrogen, the aromatic ring (benzene) serves as the parent → benzenamine. The methyl on nitrogen takes the "N-" prefix → N-methylbenzenamine. ("N-methylaniline" is acceptable as a retained name but benzenamine is the systematic IUPAC parent.) (NCERT Class 12 Chemistry Chapter 9, page 260.)
Why A is wrong: A is wrong — 'N-methylaniline' uses the trivial name 'aniline' rather than the systematic IUPAC parent 'benzenamine'. It is a retained/acceptable name but not the strict systematic IUPAC name.
Why C is wrong: C is wrong — 'N-phenylmethanamine' incorrectly treats the smaller methyl chain as parent. The larger group (benzene ring) should be the parent.
Why D is wrong: D is wrong — 'methylphenylamine' is a common name, not IUPAC nomenclature.
MCQ 7Concept TrapPractice
In Hofmann elimination, why does the least substituted alkene form preferentially?
Show answer and why every option is right or wrong
Answer: B. B is correct. The large trimethylammonium leaving group creates steric crowding around the more substituted (internal) β-hydrogens. The base abstracts the less hindered (terminal) β-hydrogen, yielding the less substituted alkene (Hofmann product). This is a steric, not electronic, control (trap: Hofmann vs Saytzeff reversal).
Why A is wrong: A is wrong — the leaving group doesn't stabilise the product alkene. Product stability would favour the more substituted alkene (Saytzeff), which is NOT what forms here.
Why C is wrong: C is wrong — Hofmann elimination is E2 (concerted, no carbocation intermediate). Carbocation rearrangement is an E1 phenomenon.
Why D is wrong: D is wrong — hyperconjugation stabilises more substituted alkenes, which would favour Saytzeff. The reason for Hofmann selectivity is steric hindrance at the β-carbon, not thermodynamic instability of the product.
MCQ 8CalculationPractice
Consider the quaternary salt: (CH₃)₃N⁺–CH₂–CH(CH₃)₂ OH⁻. On heating, which alkene is the major Hofmann elimination product?
Show answer and why every option is right or wrong
Answer: A. A is correct, and the first step is to count carbons. The group on nitrogen is –CH₂–CH(CH₃)₂, an isobutyl group of FOUR carbons, so no product can have five. Now find the β-hydrogens. The three N-methyl groups are α to nitrogen and have no β-H at all, so elimination cannot go that way. The only β-carbon is the CH of CH(CH₃)₂. Removing a β-H there and expelling N(CH₃)₃ forms the double bond between that carbon and the CH₂, giving (CH₃)₂C=CH₂ — 2-methylpropene. With a single available β-carbon there is no Saytzeff-versus-Hofmann choice to make here; the carbon skeleton alone fixes the answer.
Why B is wrong: B is wrong because but-1-ene, CH₂=CH–CH₂–CH₃, needs a straight-chain butyl group. The group here is branched isobutyl, and elimination does not rearrange the carbon skeleton — every carbon stays where it was.
Why C is wrong: C is wrong on carbon count: 3-methylbut-1-ene has five carbons, and the alkyl group on nitrogen has only four. Counting the carbons in the substrate before looking at the options rules this out immediately.
Why D is wrong: D is wrong for the same reason as C — 2-methylbut-1-ene is a five-carbon alkene, and this four-carbon isobutyl group cannot produce one.
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How do you solve a Amines Nomenclature question? A worked example
- 1
Given
• Substrate: tetraethylammonium hydroxide, (C₂H₅)₄N⁺ OH⁻• Reaction: strong heating (pyrolysis)
- 2
Required
Identify the major elimination product.
- 3
Concept
Hofmann elimination: quaternary ammonium hydroxide → least substituted alkene + tertiary amine + water. Anti-Saytzeff selectivity due to steric bulk of the –NR₃ leaving group.
- 4
Formula / Rule
Hofmann rule: β-elimination from quaternary ammonium salts preferentially removes the β-H from the least substituted carbon → terminal alkene.
- 5
Substitution / Analysis
All four groups on nitrogen are identical (ethyl). Each ethyl group has β-hydrogens on the terminal CH₃. Elimination from any ethyl group gives the same product: ethene (CH₂=CH₂).
- 6
Calculation
(C₂H₅)₄N⁺ OH⁻ → CH₂=CH₂ + (C₂H₅)₃N + H₂O
Since all groups are equivalent, there is no substitution-selectivity question — ethene is the sole alkene product. - 7
Final answer
Major product: ethene (CH₂=CH₂), with triethylamine as the amine by-product.
- 8
Common trap
Picking a higher alkene (butene) by imagining two ethyl groups combine. They don't — Hofmann elimination breaks one C–N bond and removes one β-H from the same alkyl chain. Each elimination event produces a two-carbon alkene from one ethyl group.
- 9
Similar NEET-style question
"Exhaustive methylation of propan-1-amine followed by treatment with Ag₂O and heating gives which alkene as the major product?" (Answer: propene — the only alkene possible from the propyl chain, which is also the least substituted terminal alkene consistent with Hofmann.)
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What to remember before solving Amines Nomenclature questions
Where do students lose marks on Amines Nomenclature?
These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.
Category: Organic Reaction Conditions
Quaternary ammonium hydroxide (Hofmann) elimination favours LESS substituted alkene (anti-Saytzeff). Halide elimination (E2) follows Saytzeff (more substituted).
When it triggers
E2 elimination question with quaternary ammonium hydroxide vs alkyl halide.
How to avoid
Hofmann: bulky leaving group + base → least substituted alkene (Hofmann product). Saytzeff: alkyl halide + base → most substituted alkene (Zaitsev product).
Root cause: concept gap
Correction
Hofmann (quaternary R₄N⁺ + OH⁻): least substituted alkene. Saytzeff (alkyl halide + base): most substituted.
More in Amines: 8 exam traps and mistakes · 1 formula · 3 question patterns from its other lessons.
Amines Nomenclature questions from past NEET papers
No question in our NEET 2020–2025 set targets this topic directly.
Sources
NCERT refs: Class 12 Chemistry Chapter 9, p.260
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
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