Introduction to the Nomenclature of Organic Chemicals
Introduction to the Nomenclature of Organic Chemicals
Mainly two nomenclature system are proposed for the naming of organic compounds.
Classification on the basis of carbon chain
1. Common naming system.
a) On the basis of source.
Example:
| CH4 | Marsh gas (marshy place) |
| CH3COOH | Acetic acid (vinegar) |
| HCOOH | Formic acid (Red ant) |
| CH3OH | Methyl alcohol ( wood spirit) |
b) On the basis of hydrocarbons (Radical independent).
| No. of Carbon Atoms Prefix |
| 1C form. |
| 2C acet |
| 3C propion |
| 4C butyr |
| 5C valer |
• Three carbon with one double bond—Acryl.
• Four carbon with one double bond—
| Functional Group Suffix |
| -CHO aldehyde |
| -COOH IC acid |
| -COOR alkyl-ate |
| -COX alkyl halide |
| -CONH2 amide |
| -CN Onitrile |
Radical dependent-
| Sr.no Number of Bond Suffix |
| 1) Single bond (-) ane suffix |
| 2) Double bond (=) ene suffix |
| 3) Triple(≡) bond yne suffix |
For saturated hydrocarbon—CnH2n+2- Suffix used as -ane.
• If unbranched hydrocarbon then use prefix (n)
• When one methyl group is attached to the second C-atom of the continuous chain then iso prefix is used.
• When Two methyl group is attached to the second C-atom of the continuous chain then neo prefix is used.
Note—when one hydrogen group are removed from the alkane then radical is form and called monovalent radical or alkyl. -CH3—methyl -C2H5—ethyl For unsaturated hydrocarbon…
• Double bond (CnH2n)—suffix — ene
• Triple bond (CnH2n-2)—suffix — yne
Note—unsaturated radical.
Ex -CH2=CH--- vinyl. -CH2-CH=CH2 — Allyl.
If any functional group are attached to the radical then direct functional suffix are used to radical. Name= prefix of R + Suffix of
| Functional Group Suffix |
| -OH alcohol |
| -NH2 Amine |
| -O- ether |
| -S- thio ether |
| -X- halide |
| -CN Cyanide |
| -CO- ketone. |
IUPAC NAMING SYSTEM.
Rule—
A) Selection of longest continuous parent carbon chain. B) Numbering in selected parent carbon chain.
Priority order for selection of carbon chain
(Functional group > multiple bond>number of carbon atom>substituents)
Functional group-
Multiple bond—
| Sr.no Number of Bond Suffix |
| 1) Single bond (-) ane suffix |
| 2) Double bond (=) ene suffix |
| 3) Triple(≡) bond yne suffix |
No of carbon
| Number of Carbons Root Word |
| 1C meth |
| 2C eth |
| 3C prop |
| 4C but |
| 5C pent |
| 6C hex |
| 7C hept |
| 8C oct |
Substituents means
| Substituents Prefix |
| -R alkyl |
| -NH2 amino |
| -o-N=O nitrite |
| -OCH2CH3 ethoxy |
| -CH2-Cl Chloro methyl |
| -S- thio |
| -X Halo |
Numbering of selected carbon chain--- Priority order.
Functional group>multiple bond>substituents.
Procedure of naming.
(Secondary prefix----- primary prefix----- word)
(root----- primary suffix------- Secondary suffix. )
➢ Secondary prefix means — substituents with locants
➢ Primary prefix means—cyclic group(cyclo).
➢ Word root means—number of carbon chain.
➢ Primary suffix means-- - ane, -ene, - yne.
➢ Secondary suffix means—principle fuctional groups.
➢Number and alphabets are seperated by hyphen (-).Di,tri,iso,neo and cyclo are neither seperated by comma nor by hyphen .
➢ First latter of naming is always capital letter and space required between naming.
➢ If more than one substituents then use alphabetical order of substituent names.
Examples.
Heterocyclic rings which are used during the naming…
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