Question

Ketoses such as fructose are hydroxy ketones. Ketones cannot be directly oxidized to carboxylic acids; however, hydroxy ketones can undergo _____________ via an enediol intermediate to produce an aldehyde under Tollens test basic conditions.

Answer 1

Hydroxy ketones like fructose can be oxidized via an enediol intermediate to produce an aldehyde in the presence of Tollens' reagent, even though ketones are generally resistant to oxidation.

Step-by-step explanation:

Ketoses such as fructose are hydroxy ketones. Ketones cannot be directly oxidized to carboxylic acids; however, hydroxy ketones can undergo oxidation via an enediol intermediate to produce an aldehyde under Tollens test basic conditions. Unlike aldehydes, ketones are relatively resistant to further oxidation, which explains why special precautions are not required to isolate them. In contrast, aldehydes can be easily oxidized to carboxylic acids. Ketoses are a type of sugar containing a ketone group; examples include dihydroxyacetone and fructose. When hydroxy ketones are subject to the Tollens' test, they first isomerize to form an enediol which then oxidizes to form an aldehyde that can be detected by the Tollens' reagent.