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# Which one of the following will react fastest with $H_2$ under catalytic hydrogenation condition?

$\begin{array}{1 1} a \\ b \\ c \\ d\end{array}$

Saytzeff Rule implies that base-induced eliminations (E2) will lead predominantly to the olefin in which the double bond is more highly substituted, i.e. that the product distribution will be controlled by thermodynamics.
The use of sterically hindered bases raises the activation energy barrier for the pathway to the product predicted by Saytzeff's Rule. Thus, a sterically hindered base will preferentially react with the least hindered protons, and the product distribution will be controlled by kinetics.
From amongest given olefins(a) and (b) are less stable (Saytzeff's rule).Moreover syn-isomer is more reactive than anti because of sterical hindrance.
Hence (a) is the correct option.
edited Mar 25, 2014