Q.Predict the major product when 2-methylbut-2-ene is converted into an alcohol by each of the following methods:

Step 1. 2-Methylbut-2-ene is (CH3)2C=CH-CH3, with C2 (bearing two methyls) more substituted than C3 (bearing one methyl and one H).

Step 2. (i) Acid-catalysed hydration (Markovnikov): H+ adds to the less substituted C3, generating the more stable TERTIARY carbocation at C2, which water then captures -- giving 2-methylbutan-2-ol, (CH3)2C(OH)-CH2-CH3.

Step 3. (ii) Hydroboration-oxidation (anti-Markovnikov): boron (then OH) adds to the LESS substituted carbon, C3 -- giving 3-methylbutan-2-ol, (CH3)2CH-CH(OH)-CH3, the opposite regiochemistry to (i). …

Apply each method's own regiochemical rule (Markovnikov for acid hydration, anti-Markovnikov for hydroboration, syn-dihydroxyla …

• Applying Markovnikov's rule to the hydroboration case by mistake -- hydroboration is specifically ANTI-Markovnikov, giving the opposite alcohol to acid hydration. …