Read the Passage carefully and answer the questions.
The carbonyl group of aldehydes and ketones is highly polar. The positively charged carbon is readily attacked by electron-rich nucleophile and the negatively charged oxygen atom is attacked by an electro-deficient electrophile. Aldehydes and ketones undergo nucleophilic addition reactions in the presence of acid or a base. The mechanism involves attack of a nucleophile on the electron deficient carbonyl carbon to form a tetrahedral intermediate. A new bond is formed between the carbon and oxygen. Protonation of the anion furnished by the reaction medium yields a neutral addition product. The addition product is same whether the reaction is catalyzed by acid or a base. For example in the presence of base aldehydes and ketones react with hydrogen cyanide to form cyanohydrin.
What is the product formed when an aldehyde other than formaldehyde is treated with Grignard reagent?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Secondary alcohol **
When an aldehyde (other than formaldehyde) reacts with a Grignard reagent (RMgX) followed by acid hydrolysis:
- The alkyl group (R⁻) adds to the carbonyl carbon.
- After hydrolysis, the product is a secondary alcohol.
- Formaldehyde + RMgX → primary alcohol
- Other aldehydes + RMgX → secondary alcohol
- Ketones + RMgX → tertiary alcohol
Correct answer: Secondary alcohol