CHEMCA
EXAM MASTER REVIEW SHEET
IUPAC Nomenclature of Organic Compounds
Standardized Naming Logic for JEE Main, Advanced & NEET
1. General Format of a Name
Secondary Prefix
+
Primary Prefix
+
Word Root
+
Primary Suffix
+
Secondary Suffix
Substituents
Cyclo / Bicyclo
No. of Carbons
ane / ene / yne
Main Funct. Group
2. The Golden Rules
Selection of Principal Chain (Priority Order):
Principal Functional Group > Multiple Bonds (Double > Triple) > No. of Carbon atoms > Substituents
Lowest Locant Rule
Number the chain such that the principal functional group gets the lowest possible number. If groups are at equivalent positions, follow alphabetical order for substituents.
Alphabetical Order
While writing the name, prefixes (substituents) are listed alphabetically. Note: di, tri, tetra are ignored; but iso and neo are considered.
3. Priority Table (Decreasing Order)
| Class | Formula | Prefix (Sub) | Suffix (Main) |
|---|---|---|---|
| Carboxylic Acid | $-COOH$ | Carboxy- | -oic acid |
| Sulphonic Acid | $-SO_3H$ | Sulpho- | -sulphonic acid |
| Ester | $-COOR$ | Alkoxycarbonyl- | -oate |
| Acid Halide | $-COX$ | Halocarbonyl- | -oyl halide |
| Amide | $-CONH_2$ | Carbamoyl- | -amide |
| Cyanide | $-CN$ | Cyano- | -nitrile |
| Aldehyde | $-CHO$ | Formyl / Oxo | -al |
| Ketone | $>C=O$ | Oxo / Keto | -one |
| Alcohol | $-OH$ | Hydroxy- | -ol |
| Amine | $-NH_2$ | Amino- | -amine |
4. Bicyclo & Spiro Compounds
Bicyclo Compounds
Bicyclo [x.y.z] alkane
- • Start numbering from bridgehead atom.
- • Go through the longest path first, then medium, then shortest.
- • x, y, z are no. of carbons in bridges (descending).
Spiro Compounds
Spiro [x.y] alkane
- • Start numbering from atom adjacent to spiro atom in the smaller ring.
- • Go through the smaller ring first.
- • x, y are no. of carbons in rings (ascending).
5. Essential Trivial Names
Isoprene
2-methyl-1,3-butadiene
Glycerol
Propane-1,2,3-triol
Acetone
Propan-2-one
Vinyl Group
$CH_2=CH-$
Critical Note: When a carbon-containing functional group (like $-COOH, -CHO, -CN$) is directly attached to a ring or if there are more than two such groups on a straight chain, we use special suffixes: carboxylic acid, carbaldehyde, carbonitrile. In these cases, the carbon of the functional group is not included in the parent chain numbering.
No comments:
Post a Comment