Which of the following will not respond to Fehling's Test?
(A) Benzaldehyde
(B) Acetone
(C) Acetaldehyde
(D) Acetophenone
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (D) only
Fehling’s Test gives a positive result (red precipitate of Cu₂O) only with:
- Aliphatic aldehydes (R–CHO)
- α-Hydroxy ketones
- Reducing sugars
It does not work with:
- Aromatic aldehydes (like benzaldehyde)
- Ketones (aliphatic or aromatic)
Now check the options:
|
Compound |
Type |
Fehling’s Test |
Reason |
|
(A) Benzaldehyde |
Aromatic aldehyde |
Negative |
Aromatic aldehydes do not respond |
|
(B) Acetone |
Aliphatic ketone |
Negative |
Ketones do not give Fehling’s |
|
(C) Acetaldehyde |
Aliphatic aldehyde |
Positive |
Gives red ppt |
|
(D) Acetophenone |
Aromatic ketone |
Negative |
Ketones do not give Fehling’s |
∴ Compounds that do not respond to Fehling’s test: (A), (B), and (D)