Question

Give the IUPAC name of the following compound.

${\text{CH}}_2=\text{CH}-{\text{CH(CH}}_3{)}_2$

• A. 2- methyl but- 1- ene
• B. 3- methyl but- 1- ene
• C. 2- methyl but- 3- ene
• D. Pentene

Answer 1

The correct option is B

3- methyl but- 1- ene

Let us begin by numbering the longest chain. No matter which outer carbon we start with, the longest chain is 4 carbons long.

Only one methyl substituents at carbon number 3 and the double bond is present between carbon 1 and carbon 2.

Hence the name is 3- methyl but- 1- ene.