Organic ReactionsMedium

SN1 or SN2 mechanism?

A tertiary alkyl halide reacts with a weak nucleophile in a protic solvent. Which mechanism prevails?

Given data

3° substrateWeak nucleophileProtic solvent

Steps

0 / 1

The mechanism depends on substrate, nucleophile and solvent. A tertiary substrate is too hindered for the nucleophile to attack from behind (SN2 disfavored); with a weak nucleophile and a protic solvent — which solvates and stabilizes ions — ionization to a stable 3° carbocation is favored. So I assess steric hindrance and carbocation stability.
Write your working — the numerical result must appear in the text

Full worked solution

The mechanism depends on substrate, nucleophile and solvent. A tertiary substrate is too hindered for the nucleophile to attack from behind (SN2 disfavored); with a weak nucleophile and a protic solvent — which solvates and stabilizes ions — ionization to a stable 3° carbocation is favored. So I assess steric hindrance and carbocation stability.
SN1: the 3° substrate is too hindered for SN2; the 3° carbocation is stable and the protic solvent solvates it. Rate = k[RX] (1st order).

Result:SN1

Keep studying