(a) Hydrolysis of 2-Bromobutane

• Step 1 (Identification of Mechanism): [0.5 Mark] The hydrolysis of 2-bromobutane to form $(\pm)$-butan-2-ol proceeds via the $S_N1$ mechanism.
• Step 2 (Reasoning and Mechanism): [1.0 Mark] 2-Bromobutane is a secondary alkyl halide. The reaction involves the formation of a planar carbocation intermediate ($CH_3CH^+CH_2CH_3$). Since the nucleophile ($OH^-$) can attack the planar carbocation from either side with equal probability, it results in a racemic mixture (equimolar mixture of both enantiomers), which is optically inactive.

(b) Reaction of Chlorobenzene and Methyl Chloride with Sodium

• Step 1 (Reaction Equation): [1.0 Mark] This is the Wurtz-Fittig reaction. When a mixture of an aryl halide and an alkyl halide is treated with sodium in dry ether, an alkylarene is formed.

$$C_6H_5Cl + 2Na + CH_3Cl \xrightarrow{\text{dry ether}} C_6H_5CH_3 + 2NaCl$$

• Step 2 (Final Concluded Answer): [0.5 Mark] The product formed is Toluene (methylbenzene).

💡 EL10 Concept Insight:

Think of the $S_N1$ reaction like a flat pancake: because the middle part is flat, the incoming "topping" (nucleophile) can land on either the top or the bottom side, creating a 50/50 mix of two mirror-image versions. For the Wurtz-Fittig reaction, imagine sodium as a "molecular glue" that grabs the chlorine atoms from both the ring and the chain, forcing the two remaining pieces to snap together into one molecule.