In the addition of sodium bisulfite to carbonyl system, which of the following is nucleophile?
Correct answer: B. Sulphite ion
- A. Sulphide ion
- B. Sulphite ion
- C. Hydride ion
- D. Sodium ion
Explanation
In the addition of sodium bisulfite (NaHSO3) to a carbonyl system, the nucleophile is the sulfite ion (SO32-). Sodium bisulfite reacts with carbonyl compounds, such as aldehydes and ketones, in a nucleophilic addition reaction. The sulfur atom in the sulfite ion (SO32-) bears a partial negative charge, making it a nucleophile. The nucleophilic sulfur attacks the electrophilic carbon of the carbonyl group, forming an addition product known as a bisulfite adduct. The reaction can be represented as follows: R-C=O + NaHSO3 → R-C(HSO3)O-Na+ (Bisulfite adduct) In this reaction, the sulfite ion (SO32-) acts as the nucleophile and adds to the carbonyl carbon, resulting in the formation of the bisulfite adduct. Therefore, option b is correct.
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About Aldehydes and Ketones
Aldehydes and ketones contain the polar carbonyl group, but aldehydes are generally more readily oxidised and more reactive than ketones. Coverage includes preparation by oxidation or reduction routes, nucleophilic addition of reagents such as hydrogen cyanide and bisulfite, and tests that distinguish aldehydes from ketones.
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