Question

What is the IUPAC name of the following compound?

\[\begin{array}{cc}
\ce{CH3 - CH - CH - CH2 - CH - CH2 - CH2 - CH3}\\
\phantom{}|\phantom{.....}|\phantom{.............}|\phantom{...............}\\
\phantom{}\ce{CH3}\phantom{.}\ce{CH3}\phantom{..........}\ce{C2H5}\phantom{...........}
\end{array}\]

Options

• 4-Ethyl-6, 7-dimethyloctane

• 2, 3-Dimethyl-5-ethyloctane

• 5-Ethyl-2, 3-dimethyloctane

• 5-Ethyl-2, 2, 3-dimethylheptane

Answer 1

5-Ethyl-2, 3-dimethyloctane

Explanation:

The numbering of the longest carbon chain is as follows:

\[\begin{array}{cc}
\ce{^1CH3 - ^2CH - ^3CH - ^4CH2 - ^5CH - ^6CH2 - ^7CH2 - ^8CH3}\\
\phantom{...}|\phantom{.......}|\phantom{...............}|\phantom{....................}\\
\phantom{.......}\ce{CH3}\phantom{...}\ce{CH3}\phantom{...........}\ce{C2H5}\phantom{....................}
\end{array}\]

Eight carbon atoms make up the longest chain. Carbon 5 has one ethyl substituent and carbon 2 and 3 have two methyl substituents. As a result, the compound's name is 5-Ethyl-2, 3-dimethyloctane.