Acid-catalysed hydration template

2-Methylpropene takes H⁺ to form the tert-butyl cation, water adds and loses H⁺ to give tert-butanol.

Mechanism step by step

Water adds across C=C (Markovnikov) with H₃O⁺ as the catalyst

1. Protonation – The π bond takes H⁺ from H₃O⁺
2. Water adds – Water attacks the tertiary cation
3. Deprotonation – H₃O⁺ is regenerated

Key points

• The reverse reaction is acid-catalysed dehydration (E1): excess water favours the alcohol.
• Markovnikov orientation; carbocation rearrangements are possible.
• Hydroboration–oxidation gives the anti-Markovnikov alcohol instead.
• Industrial ethanol is made by hydrating ethene over H₃PO₄.

Drawn with 45 atoms, 9 arrows, 5 shapes – every one editable in MolDraw.

Sources

• Clayden, Greeves & Warren, Organic Chemistry, 2nd ed., OUP 2012, ch. 19 Textbook
• Smith, March's Advanced Organic Chemistry, 8th ed., Wiley 2020 Textbook