Write the structure of all the alkenes that can be hydrogenated to from 2-mrthyl pentane.

Options

A. `3`
B. `4`
C. `5`
D. `2`

Answer

B

Explanation

Alkenes must have the same skeletal arrangements as the alkane because hydrogenation does not change the skeleton:
`C-underset(C )underset(|)C-C-C-C`
There are four different positions for the double bond in the above skeleton. Hence, the four different alkenes are
`CH_(3)-underset(CH_(3))underset(|)CHCH_(2)CH=CH_(2),CH_(3)-underset(CH_(3))underset(|)CHCH=CHCH_(3)`
`CH_(3)underset(CH_(3))underset(|)C=CHCH_(2)CH_(3),H_(2)C=underset(CH_(3))underset(|)C CH_(2)CH_(2)CH_(3)`