# What are the parameters of protonation of a molecule?

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 $\ce{O}$?

• 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. – Mithoron Jul 24 '17 at 20:34
• 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? – bonCodigo Jul 28 '17 at 5:43

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'.