Which of the following compounds will react with Tollens reagent ?
Correct answer: A. CH3-CHO
- A. CH3-CHO
- B. CH3-CH-CH3
- C. CH3-COOH
- D. CH3-CO-CH2-CH3
Explanation
Tollens reagent oxidizes aldehydes to carboxylate ions while Ag+ is reduced to metallic silver, producing the characteristic silver mirror. CH3CHO is an aldehyde, so it reacts, whereas the other listed compounds are an alkane, a carboxylic acid and a ketone. The common mistake is to select the ketone because it also contains a carbonyl group, but ordinary ketones do not reduce Tollens reagent.
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About Reactivity of Aldehydes and Ketones
The polar carbonyl group makes aldehydes and ketones undergo nucleophilic addition, reduction and condensation reactions. Aldehydes are generally more reactive and oxidise readily to carboxylic acids, whereas ketones resist mild oxidation; reactions with hydrogen cyanide, sodium bisulfite and 2,4-DNP help identify their behaviour.
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