Reaction Analysis: Formation of Major Product X

The given reaction involves a cyclic ketone (cyclopentanone) undergoing a reaction with methyl magnesium bromide (CH₃MgBr), followed by hydrolysis. This is a classic example of a Grignard reaction with a ketone.

Step-by-Step Mechanism:

Step 1: Nucleophilic Addition
Methyl magnesium bromide (a Grignard reagent) acts as a strong nucleophile. The nucleophilic carbon of the CH₃^- group attacks the electrophilic carbonyl carbon of cyclopentanone. $R{\mathrm{MgBr}}_1+C=O\to R-C-O{\mathrm{MgBr}}^{+}$ This results in the formation of a magnesium alkoxide intermediate.

Step 2: Hydrolysis
In the subsequent step, the reaction mixture is hydrolyzed (treated with H₂O or a dilute acid). This step protonates the alkoxide group, converting it into a hydroxyl group ($-\mathrm{OH}$). The final product is a tertiary alcohol.

Final Answer:
For a ketone, the Grignard reaction produces a tertiary alcohol. Since the starting material is a symmetrical ketone (cyclopentanone), the product is 1-methylcyclopentanol.
Therefore, the correct structure of the major product 'X' is:

Related Concepts & Theory

Grignard Reagents: Organomagnesium compounds (R-MgX) that are strong nucleophiles and bases. They react with carbonyl compounds to form alcohols.

Reaction Summary:

• Formaldehyde (HCHO) + R-MgX → Primary Alcohol
• Aldehyde (R'CHO) + R-MgX → Secondary Alcohol
• Ketone (R'COR") + R-MgX → Tertiary Alcohol
• Ester (R'COOR") + R-MgX → Tertiary Alcohol (after two additions)

Important Formulae

The general reaction for a ketone with a Grignard reagent is: $$R\text{'}R"C=O+R{\mathrm{MgX}}_1\underset{1.Et2O,2.H_3{O}^{+}}{\to }R\text{'}R"RC-OH$$

Key Point: The reaction is highly moisture-sensitive and must be performed under anhydrous conditions, as Grignard reagents are destroyed by water and protic solvents.