Guest

Why don't ketone give tollens test after all they also have alpha hydrogen?

Why don't ketone give tollens test after all they also have alpha hydrogen? 

Grade:12th pass

2 Answers

Arun
25750 Points
4 years ago
Tollens' reagent gives a negative test for most ketones, with alpha-hydroxy ketones being one exception. The test rests on the premise that aldehydes are more readily oxidized compared with ketones; this is due to the carbonyl-containing carbon in aldehydes having an attached hydrogen.
Vikas TU
14149 Points
4 years ago
Dear student 
There is misconception that all alpha hydrogen gives Tollens test
Aldehydes give a positive test, and so only alpha-hydroxy ketones that can tautomerize to aldehydes will give a positive Tollen's test
Example – 1-hydroxy-2-propanone, which isomerizes to 2-hydroxypropanol. Most alpha-hydroxy ketones with names that match the pattern 1-hydroxy-2-alkanone will give a positive Tollens' test.
Hope this helps 
Good Luck 

Think You Can Provide A Better Answer ?

ASK QUESTION

Get your questions answered by the expert for free