Question

The IUPAC name of the compound

$C{H}_3-CH\left(C{H}_3\right)-CH\left(C{H}_3\right)-CH=CH-C{H}_2-CHO$ is:

• A. 5,6-Dimethylhept-3-en-1-al
• B. 2,3-Dimethyl-4-en-7-al
• C. 5,6-Dimethylhept-2-ene-1-al
• D. 5,6-Isopropylpent-3-ene-1-al

Answer 1

The correct option is A 5,6-Dimethylhept-3-en-1-al

The IUPAC name of the given compound is 5,6-dimethylhept-3-en-1-al. It is an aldehyde. The parent is aldehyde functional group.Hence, its name ends in -al.
The parent hydrocarbon contains 7 carbon atoms and contains a double bond between third and fourth carbon atom. Hence, it is named as hept-3-en. Two methyl groups are present as substituents at fifth and sixth carbon atoms.
In the name given in option B, the aldehyde carbon is numbered 7 which is not the lowest number. Hence, this name is not correct.
In the name given in option C, the position of the double bond is incorrectly mentioned. Hence, this is also not the correct IUPAC name.
In the name given in option D, the parent hydrocarbon chain contains 5 carbon atoms which is not the longest chain. Hence, this name is also incorrect.