Which of the following compounds will give a positive silver mirror test with Tollens' reagent but a — Aldehydes Ketones and Carboxylic Acids Chemistry Question
Question
Which of the following compounds will give a positive silver mirror test with Tollens' reagent but a negative test with Fehling's solution?
Answer: A
💡 Solution & Explanation
Both aliphatic and aromatic aldehydes reduce Tollens' reagent to a silver mirror. However, Fehling's solution is a weaker oxidizing agent than Tollens' reagent and can only oxidize aliphatic aldehydes. Aromatic aldehydes like benzaldehyde lack the aliphatic $\alpha$ -hydrogens required to easily reduce the $Cu^{2+}$ in Fehling's solution. Formic acid and acetaldehyde give both tests.
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