Consider this reaction. Which reaction would be faster: this reaction or the reaction of propene (H₂C=CHCH₃) with methanol to give isopropyl methyl ether (CH₃)₂CH-OCH₃? Explain. Hammond's postulate should be part of your explanation.

Question

Consider this reaction. Which reaction would be faster: this reaction or the reaction of propene (H<sub>2</sub>C=CHCH<sub>3</sub>) with methanol to give isopropyl methyl ether (CH<sub>3</sub>)<sub>2</sub>CH-OCH<sub>3</sub>? Explain. Hammond's postulate should be part of your explanation.

Quizplus · Accepted Answer

The Answer is We let the relative energies of the carbocation intermediates guide us and invoke Hammond's postulate, which says that the energies of the transition states should be approximated by the energies of the carbocation intermediates. Hence, the reaction with the more stable carbocation intermediate should be the faster reaction. Because addition to propene involves a secondary carbocation, whereas the reaction above involves a more stable tertiary carbocation, the reaction above is a lot faster.
You must specifically mention the connection between transition states and reactive intermediates (for example, carbocations) for full credit.

Consider This Reaction