Question

2-methyl pentane is a chain isomer of

• A. 3-methyl pentane
• B. Neopentane
• C. 2,2 -dimethyl butane
• D. Isohexane

Answer 1

The correct option is C 2,2 -dimethyl butane


As we can see in the above mentioned compound, the longest chain contains five carbons atoms. Any compound having the same molecular formula but difference in the number of carbon atoms in its longest chain will be considered as chain isomers.


$\left(a\right)$

$\left(b\right)$

$\left(c\right)$

$\left(d\right)$

Structure $\left(a\right)$:
The IUPAC name of this compound is 2-methyl pentane, which is the compound given in the question. Isohexane is its common name. A compound can not be a chain isomer of itself.

Structure $\left(b\right)$:
3-methyl pentane is a positional isomer of 2-methyl pentane and not a chain isomer because, the number of carbon atoms in the longest chains of both the compounds are the same. Only the position of the methyl groups are different.

Structure $\left(c\right)$:
2,2- dimethyl propane is also not a chain isomer of 2-methyl pentane because, the molecular formula of both the compounds are different.

Structure $\left(d\right)$:
2,2- dimethyl butane is a chain isomer of 2- methyl pentane because, the molecular formula of both the compounds are the same but the number of carbon atoms in the longest chains differ.