To name an amine two ways: the common name adds the alkyl group before the word "amine" as one word (CH3NH2 = methylamine). The IUPAC name drops the "e" of the alkane and adds "amine" (CH3NH2 = methanamine). Groups sitting on the nitrogen get an "N-" in front. Memory hook: "N sits on Nitrogen" - any group tied to N is written with a capital N-.
Common names add the alkyl group before "amine"; IUPAC names replace the alkane's final "e" with "amine". Any group attached to the nitrogen atom gets a capital N- prefix (as in N-methylethanamine).
Your doubts, answered
What is the IUPAC name of CH3NH2 and why not methylamine?
IUPAC name is methanamine. In IUPAC you take the alkane (methane), drop the final 'e', and add 'amine' -> methan + amine = methanamine. 'Methylamine' is the COMMON name (alkyl group 'methyl' + 'amine' written as one word). Both mean the same molecule; NEET can ask either, so learn both columns.
When do I put an N- in front of an amine name?
Use N- for any alkyl or aryl group that is attached directly to the nitrogen atom (in secondary and tertiary amines). The N- tells the examiner the group is on nitrogen, not on the carbon chain. Example: CH3NHCH2CH3 = N-methylethanamine. Here the longest chain (ethane -> ethanamine) is the parent, and the methyl is on N, so it becomes N-methyl.
How do I pick the parent chain and the N-substituent in a secondary amine?
Choose the LARGEST alkyl group as the parent chain and name it as an alkanamine. The smaller group(s) on nitrogen become N-substituents. In CH3NHCH2CH3: ethyl (2 carbons) is bigger than methyl (1 carbon), so parent = ethanamine and methyl = N-methyl -> N-methylethanamine.
What is the IUPAC name of aniline (C6H5NH2)?
IUPAC name is benzenamine (aniline is also an accepted name). Rule for arylamines: take the arene (benzene), replace the final 'e' with 'amine' -> benzen + amine = benzenamine. Aniline is the widely used common name and NCERT accepts it as IUPAC too.
How do I name a compound with two -NH2 groups?
Number the carbons carrying the -NH2 groups, add a prefix di/tri, and KEEP the 'e' of the parent alkane before the suffix. Example: H2N-CH2-CH2-NH2 = ethane-1,2-diamine. Note 'ethane' keeps its 'e' because the word after it (diamine) starts with a consonant.
For (CH3CH2)3N, why is it N,N-diethylethanamine?
There are three ethyl groups on nitrogen. Pick one ethyl as the parent chain -> ethanamine. The other two ethyl groups are on nitrogen, so each gets an N- -> N,N-diethyl. Combined: N,N-diethylethanamine. Two N's are written because two separate groups sit on the same nitrogen.
⚠️ The NEET trap ✗ Writing the IUPAC name of CH3NHCH3 as dimethylamine or methylmethanamine. ✓ CH3NHCH3 is N-methylmethanamine. Parent = methanamine (one CH3 as the chain), the other CH3 is on nitrogen so it is N-methyl. 'Dimethylamine' is only the COMMON name. 🧠 If a group hangs on nitrogen, it must carry a capital N- in the IUPAC name. No N- = you named it as a chain carbon by mistake.
Real NEET questions
NEET 2017
Which of the following reactions is appropriate for converting acetamide (CH3CONH2) to methanamine (CH3NH2)?
A · Carbylamine reaction
B · Hoffmann bromamide (hypobromite) reaction ✓
C · Stephen's reaction
D · Gabriel's phthalimide synthesis
Solution: First note the naming: CH3NH2 is called methanamine in IUPAC (methane -> drop 'e' -> add 'amine'), which is the same as the common name methylamine. Acetamide has 2 carbons and methanamine has 1 carbon, so we need a reaction that removes one carbon. The Hoffmann bromamide degradation (Br2/KOH) turns a primary amide into a primary amine with ONE fewer carbon: CH3CONH2 -> CH3NH2. Carbylamine is only a test, Stephen's gives aldehydes, and Gabriel uses alkyl halides. Hence (B).
NEET 2016 Phase 1
The product formed by the reaction of an aldehyde with a primary amine is:
A · Schiff base ✓
B · Ketone
C · Carboxylic acid
D · Aromatic acid
Solution: A primary amine is written in common form as alkylamine (e.g. methylamine) and in IUPAC as alkanamine (e.g. methanamine). Its lone pair on nitrogen attacks the aldehyde carbon, then loses water to give an imine R-CH=N-R', called a Schiff base. No oxidation happens, so no ketone or acid forms. Hence (A). This confirms the -NH2 group (primary amine) is the reactive part you must correctly identify when naming.
Solved Amines NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Aniline is the common name, but NCERT accepts it as an IUPAC name too. The strict IUPAC name is benzenamine (benzene -> replace 'e' with 'amine').
Do I keep or drop the 'e' of the alkane when naming amines?
Drop the 'e' when 'amine' follows directly (methane -> methanamine). KEEP the 'e' when a prefix like di/tri comes before amine (ethane -> ethane-1,2-diamine).
What is the difference between methylamine and methanamine?
None in the molecule. Methylamine is the common name (alkyl group + amine as one word) and methanamine is the IUPAC name (alkane 'e' replaced by amine). Both are CH3NH2.
How are tertiary amines named in IUPAC?
Take the largest chain as the parent alkanamine and name every group on nitrogen with an N- prefix. Example: (CH3CH2)3N = N,N-diethylethanamine.
Why does NEET care about naming amines?
Reaction questions name the product by its IUPAC name (like methanamine). If you cannot match the name to the structure, you can lose easy marks even when you know the reaction.
