Conditions
Dilute acid in an alcohol or water (compare base, which attacks the less hindered carbon).
Mechanism in 3 steps
Red curly arrows show where each pair of electrons moves.
About substitution reactions
In a substitution, a nucleophile replaces a leaving group on a saturated carbon. Whether it happens in one step (SN2) or through a carbocation (SN1) depends on the substrate, the nucleophile and the solvent.
Practise this mechanismDraw the curly arrows yourself and Bondline checks each one. Or add it to your notes and watch it in 3D.
Open in Bondline