Which alkene would you expect to have the highest heat of hydrogenation?
A)I
B)II
C)III
D)IV

Question

Which alkene would you expect to have the highest heat of hydrogenation? 
A)I 
B)II 
C)III 
D)IV

Quizplus · Accepted Answer

Alkene IV has the highest heat of hydrogenation because it has three alkyl groups and a trans double bond. The three alkyl groups provide a significant amount of steric hindrance, making it more difficult for hydrogen atoms to approach the double bond for addition. Because of this, the transition state for the addition of hydrogen is more unstable than for the other alkenes, resulting in a higher heat of hydrogenation.

Which Alkene Would You Expect to Have the Highest Heat