Question

Write the IUPAC name of the following compounds given:
a) \[C{H_3} - C{H_2} - C{H_2} - CH(C{H_3}) - C{H_3}\]
b) \[C{H_3} - CH(C{H_2} - C{H_3}) - C{H_2} - C{H_2} - C{H_3}\]

Answer 1

Hint: In both the given compounds the longest chain contains 5 carbon atoms which denotes that the hydrocarbon chain is pentane. In both compounds two different hydrocarbon groups are attached.


Complete step by step answer:
IUPAC system is used for the naming of the chemical compound with the help of rules.
(a) \[C{H_3} - C{H_2} - C{H_2} - CH(C{H_3}) - C{H_3}\]
(1) Step-1- Determine the longest chain:
The parent chain is the longest chain consisting of the maximum number of carbon atoms. In the given structure, the longest chain contains 5 carbon atoms, so the hydrocarbon chain will be pentane.
(2) Step -2- Recognize the side group attached to the chain:
In the parent chain consisting 5 carbon atoms, one methyl group is attached to the second position of the carbon atom in the hydrocarbon chain.
(3) Determine the IUPAC name:
Due to the presence of methyl group at 2nd carbon atom in a pentane hydrocarbon chain, the resulting IUPAC name will be 2-methyl pentane.
(b) \[C{H_3} - CH(C{H_2} - C{H_3}) - C{H_2} - C{H_2} - C{H_3}\]
(1) Step-1- Determine the longest chain:
In the given structure, the longest chain contains 5 carbon atoms, so the hydrocarbon chain will be pentane.
(2) Step -2- Recognize the side group attached to the chain:
In the parent chain consisting 5 carbon atoms, one ethyl group is attached to the second position of the carbon atom in the hydrocarbon chain.
(3) Determine the IUPAC name:
Due to the presence of ethyl group at 2nd carbon atom in a pentane hydrocarbon chain, the resulting IUPAC name will be 2-ethyl pentane.

Note: The numbering in the hydrocarbon chain is done according to the group attached to it. If a functional group is present the numbering starts from there. When any highest priority groups are present then numbering starts from there. The number in the IUPAC name denotes the position of the group attached.