Which of the following pairs give positive Tollen’s test?

Question

Which of the following pairs give positive Tollen’s test? (A) Glucose, sucrose (B) Glucose, fructose (C) Hexaual, acetophenone (D) Fructose, sucrose

Tardigrade Admin · Accepted Answer

Only aldehyde give positive Tollen's test. However under the strongly basic condition of the test α -hydroxy ketones can isomerize to aldehydes (i.e. endiol rearrangement in fructose that inter convert ketones to aldoses.) so that's why will also gives a positive Tollen's test α -hydroxy ketones.

Q. Which of the following pairs give positive Tollen’s test?

Glucose, sucrose

Glucose, fructose

Hexaual, acetophenone

Fructose, sucrose

Only aldehyde give positive Tollen's test. However under the strongly basic condition of the test α -hydroxy ketones can isomerize to aldehydes (i.e. endiol rearrangement in fructose that inter convert ketones to aldoses.) so that's why will also gives a positive Tollen's test α -hydroxy ketones.