Exam Master Review Sheet - IUPAC Nomenclature

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EXAM MASTER FORMULA SHEET

IUPAC Nomenclature of Organic Compounds

Standardized Naming Logic for JEE Main, Advanced & NEET

1. General Format of a Name

Every IUPAC name consists of five primary components written sequentially without spaces:

2° Prefix + 1° Prefix + Word Root + 1° Suffix + 2° Suffix

Substituents
(fluoro, chloro, methyl, methoxy)

Cyclic Nature
(cyclo, bicyclo, spiro)

No. of Carbons
(meth, eth, prop, but...)

Saturation
(-ane, -ene, -yne)

Principal F.G.
(-oic acid, -ol, -al, -one)

2. The Golden Rules of Selection & Numbering

1. Principal Chain Selection Priority:

Principal Functional Group
↓
Maximum Multiple Bonds (= / $\equiv$)
↓
Maximum Number of Carbon Atoms
↓
Maximum Number of Substituents

2. Numbering Priority (Lowest Locant):

Principal Functional Group
↓
Double Bond ($=$)
↓
Triple Bond ($\equiv$)
↓
Substituents (Alphabetical Order)

Crucial Tie-Breaker Rules:

• Lowest Locant Set Rule: Compare the series of locants term by term. The set with the lower number at the first point of difference is correct.
• Double vs Triple Bond: If a double bond and triple bond are at identical positions from either end, the Double Bond gets priority (lower number). E.g., Pent-1-en-4-yne.
• Alphabetical Order: When writing prefixes, ignore multiplying terms like di, tri, tetra. However, iso, neo, and cyclo ARE considered for alphabetical comparison.

3. Functional Group Priority Table (Decreasing Order)

Groups at the top are Principal Functional Groups (Suffix). Groups below them act as Substituents (Prefix).

Class of Compound	Formula	Prefix (As Substituent)	Suffix (Main Chain)	Special Suffix*
Carboxylic Acid	$-COOH$	Carboxy-	-oic acid	-carboxylic acid
Sulphonic Acid	$-SO_3H$	Sulpho-	-sulphonic acid	-
Acid Anhydride	$-(CO)_2O$	-	-oic anhydride	-carboxylic anhydride
Ester	$-COOR$	Alkoxycarbonyl-	Alkyl... -oate	Alkyl... -carboxylate
Acid Halide	$-COX$	Halocarbonyl-	-oyl halide	-carbonyl halide
Amide	$-CONH_2$	Carbamoyl-	-amide	-carboxamide
Cyanide / Nitrile	$-CN$	Cyano-	-nitrile	-carbonitrile
Isocyanide	$-NC$	Isocyano-	-isonitrile	-
Aldehyde	$-CHO$	Formyl- / Oxo-	-al	-carbaldehyde
Ketone	$>C=O$	Oxo- / Keto-	-one	-
Alcohol	$-OH$	Hydroxy-	-ol	-
Thiol	$-SH$	Mercapto-	-thiol	-
Amine	$-NH_2$	Amino-	-amine	-

*Special Suffix Rule: Special suffixes are used when the carbon atom of the functional group is directly attached to a ring (e.g., Cyclohexanecarboxylic acid) or when there are more than two identical carbon-containing functional groups attached to a straight unbranched chain (e.g., Propane-1,2,3-tricarbonitrile). The carbon of the group is not counted in the parent chain.

4. Bicyclo & Spiro Compounds

Bicyclo Compounds

Bicyclo [x.y.z] alkane

• Contains two fused rings with two bridgehead carbons.
• Numbering starts from one bridgehead atom.
• Proceed along the longest bridge to the second bridgehead, then along the medium bridge back to the first, and finally the shortest bridge.
• $x \ge y \ge z$ (Descending order of carbon atoms in bridges).

Spiro Compounds

Spiro [x.y] alkane

• Contains two rings joined at exactly one common atom (spiro carbon).
• Numbering starts from the atom adjacent to the spiro carbon in the smaller ring.
• Proceed around the smaller ring, through the spiro carbon, and around the larger ring.
• $x \le y$ (Ascending order of carbon atoms in rings).

5. Complex Substituents & Trivial Names

Common Alkyl Radicals:

Isopropyl

$(CH_3)_2CH-$

Isobutyl

$(CH_3)_2CH-CH_2-$

sec-Butyl

$CH_3-CH_2-CH(CH_3)-$

tert-Butyl

$(CH_3)_3C-$

Neopentyl

$(CH_3)_3C-CH_2-$

Vinyl

$CH_2=CH-$

Allyl

$CH_2=CH-CH_2-$

Acryl / Acryloyl

$CH_2=CH-CO-$

Aromatic Rings (Benzene Derivatives):

If the principal functional group is on the side chain, the benzene ring becomes a substituent.

Phenyl: $C_6H_5-$ (Benzene as substituent)

Benzyl: $C_6H_5-CH_2-$

Benzal: $C_6H_5-CH=$

Benzo: $C_6H_5-C\equiv$

Important Trivial Names:

Toluene: Methylbenzene

Phenol: Hydroxybenzene

Aniline: Aminobenzene

Anisole: Methoxybenzene

Isoprene: 2-Methyl-1,3-butadiene

Glycerol: Propane-1,2,3-triol

Acetone: Propan-2-one

Acetylene: Ethyne

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