Question

Which of the following pairs cannot be differentiated by Tollen's reagent?

• A. Benzaldehyde and benzyl alcohol
• B. Hexanal and $2$-hexanone
• C. $2$-Hexanol and $2$-hexanone
• D. Pentanal and diethyl ether

Answer 1

Answer: (C)

$2$-Hexanol and $2$-hexanone

Tollen's reagent :- i) Tollen's reagent is silver ammonia complex. It is mild oxidizing agent.

ii) When aldehyde is warmed with ammonical silver nitrate [Tollen's reagent] a bright silver mirror is produced on the inner side of container or grayish black precipitate is obtained.

iii) Silver ion of Tollen's reagent gets reduced to mettalic silver and aldehyde gets oxidized to acetate ion.

iv) Tollen's reagent is used to distinguish aldehydes. It should be noted that, simple hydrocarbons, alcohols, ethers or ketones do not get oxidized by Tollen's reagent.

v) Hence, $2-$Hexanol and $2-$hexanone, which are alcohol and ketone respectively are not differentiated by Tollen's reagent.