IUPAC Nomenclature is the systematic method used in naming organic compounds so that each compound has one unique and internationally accepted name. It removes ambiguity and ensures uniformity in chemical communication.

1. Select the longest carbon chain containing the principal functional group.
2. Number the chain from the end nearest to the functional group or the first substituent.
3. Name the substituents (alkyl groups, halogens, nitro-group, etc.).
4. Indicate the position of substituents using numbers (locants).
5. If more than one substituent appears, use prefixes: di-, tri-, tetra-.
6. Functional groups are given priority when naming.
7. Write the name using the order: Prefix – Parent Name – Suffix (e.g., 2-methylpentan-3-ol).
8. Use commas between numbers and hyphens between numbers and words.
9. When naming compounds name in alphabetical order

1. penta-1,3-diene
   

   H   H       H   H
   |   |       |   |
   C = C — C = C — C — H
   |           |
   H           H
   

2. But-2-ene
   

   H   H       H
   |   |       |
   C — C = C — C — H
   |       |   |
   H       H   H
   

3. Methyl ethanoate
   

       H   
       |       
   H — C — C = O
       |   | 
       H   O — CH3
       CH3COOCH3
   

4. 4- chloro pent-2-ene

       H   Cl  H   H   H
       |   |   |   |   |
   H — C — C — C = C — C — H
       |   |           |
       H   H           H
       CH3CH(Cl)CHCHCH3
   

5. 2,2,5 trichloro hexane

       H   Cl  H   H   Cl  H
       |   |   |   |   |   |
   H — C — C — C — C — C — C — H
       |   |   |   |   |   |
       H   H   H   H   Cl  H
       CH3C(Cl)(Cl)CH2CH2CH(Cl)CH3
   

6. butan-2-one

   H   O   H   H
   |  ||   |   |
   C — C — C — C — H
   |       |   |
   H       H   H
   CH3COCH2CH3
   

7. 2,4 dichloro 2- methyl pentane

       H   CH3 H   H   H
       |   |   |   |   |
   H — C — C — C — C — C — H
       |   |   |   |   |
       H   Cl  H   Cl  H
    CH3C(Cl)(CH3)CH2CH(Cl)CH3
   

8. Ethanol

       H   H
       |   |
   H - C - C - O - H
       |   |
       H   H
   
      CH3CH2OH
   

9. Methoxymethane (Dimethyl ether)

       H       H
       |       |
   H - C - O - C - H
       |       |
       H       H
       CH3OCH3
      

10. 1,1,2,2 - tetrachloroethane

        Cl  Cl
        |   |
    H - C - C - H
        |   |
        Cl  Cl
    
    CH(Cl)(Cl)CH(Cl)(Cl)
    
       

11. 2-ethyl pentanoic acid

        H   H   H   C2H5  
        |   |   |   |   
    H — C — C — C — C — C = O
        |   |   |   |   |
        H   H   H   H   O — H
        CH3CH2CH2CH(C2H5)COOH