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Will an E2 reaction that has 2 potential products go faster than one that has 3 potential products? The specific question involves both molecules below reacting with methanol. I figured it's an E2 reaction (I hope I'm right) and the question is, which one will go faster?

cyclohexylbromides

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  • $\begingroup$ Could you provide specifics? $\endgroup$
    – LDC3
    Commented May 24, 2015 at 15:48
  • $\begingroup$ What are the conditions for this reaction? Only methanol is mentioned, which leads me to believe this is E1 not E2. $\endgroup$
    – jerepierre
    Commented May 24, 2015 at 17:11

1 Answer 1

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For the E1 pathway, molecule A will react faster since the intermediate is more stable than from molecule B. According to this web site, the major product for A is 1,2-dimethylcyclohexene; for B, it is 1-methylcyclohexene.

For the E2 pathway, both reactions will have nearly the same rate. Depending on the orientation of the α-methyl group (cis or trans to Br), the major product is the same for cis, but for trans it will be 2,3-dimethylcyclohexene for A and 2-methylcyclohexene for B.

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  • $\begingroup$ why is the intermediate more stable in molecule A? $\endgroup$
    – ems
    Commented May 24, 2015 at 16:21
  • $\begingroup$ The intermediate is a tertiary cation; it's more stable than a secondary cation. $\endgroup$
    – LDC3
    Commented May 24, 2015 at 16:23
  • $\begingroup$ But in the E2 mechanism there is no cation formed. $\endgroup$
    – Martin - マーチン ♦
    Commented May 25, 2015 at 11:21
  • $\begingroup$ @Martin-マーチン It's been a while since I needed to know the difference between E1 and E2. I have them switched. $\endgroup$
    – LDC3
    Commented May 25, 2015 at 12:39
  • $\begingroup$ I was confused, too, and had to look it up. And now I see a comment to the question, that makes me believe your answer is absolutely on target. $\endgroup$
    – Martin - マーチン ♦
    Commented May 25, 2015 at 12:43

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