Which one of the following reagents is used to distinguish between aldehydes and ketones?
Correct answer: B. Tollen's Reagent
- A. Alkaline Iodine
- B. Tollen's Reagent
- C. Bromine
- D. 2, 4 DNPH
Explanation
The Tollens' test is a reaction that is used to distinguish aldehydes from ketones, as aldehydes are able to be oxidized into a carboxylic acid while ketones cannot.Alkaline iodine is used in the iodoform test. When Iodine and sodium hydroxide are added to a compound that contains either a methyl ketone or a secondary alcohol with a methyl group in the alpha position, a pale yellow precipitate of iodoform or triiodomethane is formed. It can be used to identify aldehydes or ketones.A solution of bromine in CH2CL2 is used to either test for unsaturation or to check the ability to be oxidized for example in aldehydes. Bromine solution is naturally orange and when consumed in oxidation, it becomes colourless.2, 4 DNPH is used to detect ketones and aldehydes. A positive test is signalled by the formation of a yellow, orange or red precipitate of the dinitrophenylhydrazone.
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About Aldehydes and Ketones
Aldehydes and ketones contain the polar carbonyl group, but aldehydes are generally more readily oxidised and more reactive than ketones. Coverage includes preparation by oxidation or reduction routes, nucleophilic addition of reagents such as hydrogen cyanide and bisulfite, and tests that distinguish aldehydes from ketones.
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