Which alkene reacts fastest with H_2 under ca | vedclass

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(B) The rate of catalytic hydrogenation of alkenes is inversely proportional to the stability of the alkene. More substituted alkenes are more stable

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(B) The rate of catalytic hydrogenation of alkenes is inversely proportional to the stability of the alkene. More substituted alkenes are more stable due to the electron-donating inductive effect and hyperconjugation of the alkyl groups $(R)$. Therefore,the stability order is: Tetrasubstituted > Trisubstituted > Disubstituted > Monosubstituted. Since the rate of hydrogenation is inversely proportional to stability,the least substituted alkene will react the fastest. Among the given options,the alkene with the fewest substituents (disubstituted) will react the fastest. Comparing the options,the disubstituted alkenes ($A$ and $B$) are less stable than the trisubstituted $(C)$ and tetrasubstituted $(D)$ alkenes. Between the two disubstituted alkenes,the cis-isomer $(B)$ is generally less stable than the trans-isomer $(A)$ due to steric hindrance. Therefore,the cis-disubstituted alkene $(B)$ reacts the fastest.

Which alkene reacts fastest with $H_2$ under catalytic hydrogenation conditions?

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