The document discusses several common chemical tests used to identify carbonyl compounds such as aldehydes and ketones. It describes how aldehydes and ketones react in DNPH test, sodium bisulphite test, Tollen's test, Fehling's solution test, and Benedict's solution test. Specifically, it notes that aldehydes will test positive in Tollen's test and the other cupric salt tests by forming precipitates, while ketones do not react in these tests. It also explains that ketones will produce a color change in sodium nitroprusside test whereas aldehydes do not.

2. Jam Saeed Ahmed
Topic
Identification of Carbonyl Compounds

3. Tests
⮚DNPH Test
⮚Sodium Bisulphite Test
⮚Tollen’s Test ( Silver Mirror Test)
⮚Fehling Solution Test
⮚Benedicts Solution Test

4. DNPH Test
⮚Aldehydes and ketones form a yellow or red
precipitate
⮚ When treated with 2,4 dinitrophenylhdrazine
solution

5. Sodium Bisulphite Test
⮚Aldehyds and small methyl ketones form a
crystalline white precipitate
⮚When treated with saturated sodium bisulphite
solution

6. Tollen’s Test ( Silver Mirror Test)
⮚Aldehydes form silver mirror with Tollen’s reagent
(ammoniacal silver nitrate solution).
⮚Add Tollen’s reagent to an aldehyde solution in a test
tube and warm.
⮚A silver mirror is formed on the inside of the test
tube.
⮚Silver mirror High quality mirrors are manufactured
by using this principle.
⮚Ketones do not give this test.

7. Fehling's Solution Test [an alkaline solution
containing a cupric tartrate complex ion]
⮚Aliphatic aldehydes form a brick-red precipitate with
Fehling's Aldehydes and Ketones
⮚To an aldehyde solution, add Fehling's solution and
boil.
⮚A brick red precipitate of cuprous oxide is formed.
⮚Ketones do not give this test.

8. Benedict's Solution Test (un alkaline solution
containing a cupric citrate complex ion]
⮚Aliphatic aldehydes form a brick-red precipitate with
Benedicts's solution.
⮚To an aldehyde solution, add Benedict's solution and
boil.
⮚A brick-red precipitate of cuprous oxide is formed
⮚Ketones do not give this test.

9. Sodium Nitroprusside Test:
⮚Ketones produce a wine red or orange red colour on
adding alkaline sodium nitroprusside solution dropwise.
⮚Aldehydes do not give this test.

10. Lab Performance