Compound A ( $C X_{7} H X_{6} O$ ) gives a silver mirror with Tollens reagent but no precipitate with Fehling's solution. A is shaken with concentrated aqueous NaOH and the mixture is extracted with ether, which takes up the neutral product B. Which of the following is positive for B?

Aeffervescence with aqueous $NaHCO X_{3}$
Borange precipitate with 2,4-DNP
Csilver mirror with Tollens reagent
Devolution of hydrogen with sodium metal

Answer: D

A is benzaldehyde (aromatic aldehyde, Fehling negative). With concentrated alkali it undergoes the Cannizzaro reaction to give sodium benzoate (stays in water) and benzyl alcohol B (neutral, extracted by ether). Benzyl alcohol, being an alcohol, releases

H X_{2}

with sodium; it has no CHO or COOH group.

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Compound A (CX7​HX6​O) gives a silver mirror with Tollens reagent but no precipitate with Fehling's solution. A is shaken with concentrated aqueous NaOH and the mixture is extracted with ether, which takes up the neutral product B. Which of the following is positive for B?

Answer: D

More questions on Distinguishing tests for functional groups

Compound A ( $C X_{7} H X_{6} O$ ) gives a silver mirror with Tollens reagent but no precipitate with Fehling's solution. A is shaken with concentrated aqueous NaOH and the mixture is extracted with ether, which takes up the neutral product B. Which of the following is positive for B?