Which of the following has highest heat of hydrogenation:

Options

A. Methylpropene
B. But-`1`-ene
C. cis-But-`2`-ene
D. trans-but-`2`-ene

Answer

B

Explanation

The heat of hydrogenation is related to the relative stability of the alkene. The more stable the alkene, the lower the numerical value of heat of hydrogenation. The greater the number of alkyl groups bonded to the doubly bonded `C` atoms, the more stable the alkene. But-`1`-ene is the least substituted and, hence, the least stable alkene, reflected by its highest `Delta H` Hydrogenation.