Oxygenate blending for high octane gasoline: Methyl tert-butyl ether (MTBE), with a reference octane of about 115, is formed by the acid-catalysed addition of isobutylene to which alcohol?

Introduction:
MTBE has historically been a popular oxygenate and high-octane blending component. Understanding its synthesis clarifies feedstock needs and why certain refinery/petrochemical integration schemes exist (e.g., isobutylene supply and methanol availability).

Given Data / Assumptions:

• Target ether: methyl tert-butyl ether (MTBE).
• Olefins react with alcohols over acidic catalysts to form ethers.
• Isobutylene (2-methylpropene) is the olefin used.

Concept / Approach:
MTBE is produced by reacting isobutylene with methanol (methyl alcohol) over a strong acid catalyst. The tertiary carbon of isobutylene forms a stable carbocation-like intermediate under acidic conditions, favouring ether formation. Ethyl alcohol would form ETBE; methane/ethane do not supply the necessary hydroxyl group for etherification.

Step-by-Step Solution:

Verification / Alternative check:
Process descriptions list fixed-bed acidic ion-exchange resins or acidic catalysts at moderate temperatures for MTBE synthesis from isobutylene and methanol.

Why Other Options Are Wrong:

• Ethyl alcohol: Yields ETBE, not MTBE.
• Methane/Ethane: Alkanes; cannot etherify directly.
• Isopropyl alcohol: Would give IPBE, not MTBE.

Common Pitfalls:
Confusing ETBE and MTBE naming; the prefix reveals the alcohol used.

Final Answer:
Methyl alcohol