Which of the following tests is shown by ketones only?
Correct answer: A. Sodium nitroprusside test
- A. Sodium nitroprusside test
- B. Tollen's reagent test
- C. Fehling's solution test
- D. Benedict's reagent test
Explanation
Option A is correct.Sodium nitroprusside test is shown by ketones only. The sodium nitroprusside test is a chemical test used to detect the presence of ketones. It is a qualitative test, which means that it can only detect the presence or absence of a ketone. It cannot be used to quantify the amount of a ketone in a sample. Sodium nitroprusside test works on the principle that ketones react with sodium nitroprusside to produce a red-violet color. Reaction:Na2[Fe(CN)5NO] + R2C=O → Na2[Fe(CN)6] + NO + H+When a ketone that has a methyl group adjacent to the carbonyl group is treated with sodium nitroprusside in an alkaline medium, it produces a red to red-violet colouration. Aldehydes do not give this colour reaction, making it a specific test for ketones (specifically, methyl ketones).
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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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