Adding an acid replaces the $\ce{-MgBr+}$ with an $\ce{H+}$. Why does this happen? Is $\ce{H+}$ a better electrophile than $\ce{MgBr+}$?

Or, to put it another way, why doesn't $\ce{MgBr}$ stays attached to $\ce{O}$?

  • $\begingroup$ Well, it's symbolic scheme of reaction not telling what exactly Mg(OH)Br in H2O/t-butanol solution "looks like". t-butanolate isn't monomer and hydroxide is solvated, but those are kinda details. $\endgroup$ – Mithoron Jul 24 '17 at 20:34
  • $\begingroup$ Isn't that a Grignard reagent? If so, it's a strong base and a nucleophile, isn't it? Making the intermediate carbocation less stable, more reactive with acidic hydrogens? $\endgroup$ – bonCodigo Jul 28 '17 at 5:43

We are taking about electrophilicity of ions. It basically depends upon:
1. charge on the ion(+)
2. density of plus charge on it

So comparing $\ce{H+}$ and $\ce{CH3+}$, the former has a higher plus charge density so that's why it will be more attracted towards 'O'.


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.