In the final step of the mechanism, elimination occurs over substitution, why is this?

Reaction scheme

  • $\begingroup$ For tertiary carbocations elimination products are generally produced, nothing special here. On the other hand rearrangement that happens earlier is a bit interesting. $\endgroup$ – Mithoron Dec 15 '17 at 16:28

The simple answer is that water is a very weak nucleophile and substitution does happen reversibly, but usually dissociates immediately. After which, the final reaction shown happens.

There is likely a (very) minor product that follows along the substitution pathway with an alcohol final product.

| improve this answer | |
  • $\begingroup$ So if water added to the carbocation, the c-o is cleaved mostly as oppose to deprotonating and forming the alcohol? $\endgroup$ – Cubefield Dec 15 '17 at 16:05
  • $\begingroup$ That is essentially correct $\endgroup$ – Rampallian Dec 15 '17 at 16:09
  • $\begingroup$ Moreover, for the bottom two examples here: prnt.sc/hny81u why is the substitution product formed over elimination? $\endgroup$ – Cubefield Dec 15 '17 at 16:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.