Nomenclature of soluble organic compounds How to write the iupac name of soluble compounds......

2. General steps for IUPAC nomenclature of organic compounds:
To simplify the nomenclature process, differentiate the organic compounds in four
categories as:
Naming of all organic compounds can be done in three steps as,

3.  Nomenclature of saturated hydrocarbon(alkane)
1. Selection of parent chain( Longest chain rule)
If the given organic compound is branched chain structure, the longest possible
continuous chain of carbon is selected as parent chain
CH3 - CH2 – CH2 – CH – CH3
CH2 – CH2 – CH3
CH3 - CH2 – CH2 – CH – CH3
CH2 – CH2 – CH3
No. of carbon in parent chain = 7
(Correct)
No. of carbon in parent chain = 5 (wrong)

4. • If two chains of equal length are possible, select the one with maximum number of branches
CH3 - CH2 – C – CH2 – CH2 – CH2 – CH3
CH - CH3
CH3
CH2
CH3
CH3 - CH2 – C – CH2 – CH2 – CH2 – CH3
CH - CH3
CH3
CH2
CH3
Number of carbon in parent chain = 7
Number of branches = 2
(wrong)
Number of carbon in parent chain = 7
Number of branches = 3
(Correct)

5. 2. Numbering of parent chain
• Substituent rule
If only one branch is present in parent chain, the numbering of parent chain is started in such a way that
position of the substituent become lowest possible number
CH3 - CH2 – CH2 – CH – CH3
CH3
1
2
3
4
5
CH3 - CH2 – CH2 – CH – CH3
CH3
5
4
3
2
1
substituent
2- methyl
(Correct) 4 – methyl
(Wrong)
Note : the position and name of substituent should be separated by hyphen (-) .

6. b. Lowest sum rule
If more than one similar or different substituents are present in the parent chain, the numbering
of parent chain is started in such a way that the sum of position of the substituent become
lowest
CH3 - CH – CH2 – CH – C - CH3
CH3
5
4
3
2
1 6
CH3
Sum of position of substituent= 2 +3 = 5
(Correct)
CH3 - CH2 – CH2 – CH – CH2 - CH3
CH3
5
4
3
2
1 6
CH3
Sum of position of substituent = 4 + 5 = 9
(wrong)
CH3 - CH2 – CH2 – CH – CH2 - CH3
CH3
2
3
4
5
6 1
CH3
CH3
Sum of position of substituent= 2 +2+5 = 9
(Correct)
CH3 - CH – CH2 – CH – C - CH3
CH3
2
3
4
5
6 1
CH3
CH3
Sum of position of substituent= 2 +5+5 = 12
(wrong)

7. 3. Naming substituents (Alphabetical rule)
If two or more than two substituents are present, the name of the substituent should be written in
alphabetical order. If same substituents are present in different positions, the positions of each group is
separated by commas and suitable prefixes like di, tri, tetra, etc are given. However, the prefixes di, tri, tetra
are not considered while deciding the alphabetical order.
CH3- CH- CH2 – C – CH2 – CH2 – CH – CH3
CH3
CH2 – CH3
CH3
8
1
7
6
5
4
3
2
1
Prefix = 4 - Ethyl, 2,7- dimethyl
Word root = oct
Primary suffix = ane
IUPAC name = prefix + word root + primary suffix
4 – Ethyl, 2,7 dimethyloctane

8. • If two different substituents are located at equivalent positions, the numbering of the parent
chain is done in such a way that the substituent which come first in alphabetical order gets
the lowest number.
CH3 – CH2 - CH – CH2 – CH – CH2 – CH3
CH3
1
2
3
4
5
CH2 – CH3
5 - ethyl , 3 – methyl (wrong)
3- ethyl , 5 – methyl (correct)
6
7
CH3 – CH2 - CH – CH2 – CH – CH2 – CH3
CH3
7
6
5
4
3
CH2 – CH3
2
1

9. 4. Complex substituent rule
If the alkyl substituent is further branched, it is named as complex substituent, in which the carbon atom of
substituent are separately numbered in such a way that the carbon atom directly attached to the parent chain
is given number 1 and the prefix name of such substituent is written in bracket.
3
CH3- CH- CH2 – CH – CH2 – CH2 – CH2 – CH3
CH3
CH– CH3
CH3
8
7
6
5
4
3
2
1
CH2 - CH3
1
2
2,6 – Dimethyl – 4 – (1- methyl propyl) octane
CH3- CH- CH2 – CH – CH2 – CH2 – CH2 – CH3
CH3
CH– CH3
CH3
8
7
6
5
4
3
2
1
CH - CH3
1
2
2,6 – Dimethyl – 4 – (1,2 - dimethyl propyl) octane
H3C -
3

10. CH3 - C - CH2 - CH – CH3
CH3
CH3
Cl
Cl - C - CH3
Cl
Cl
CH3 - CH2 - C - CH – CH - CH3
CH3
CH3
C2H5
Cl
CH3 - CH - C - CH – CH3
NO2 CH3
Cl
CH3
• Self test
CH3 – CH2- CH- CH2 – CH – CH2 – CH – CH2 – CH2 - CH3
CH3
CH– CH3
CH3
CH2 – CH2 - CH3