Consider the following statements:
Assertion (A): A carboxylic acid does not give the test for the carbonyl group.
Reason (R): The carbonyl carbon of the carboxylic group is electron-deficient and hence less susceptible to nucleophilic attack.
Select the correct answer using the codes given below:
- A(A) is false but (R) is true
- BBoth (A) and (R) are true and (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- DBoth (A) and (R) are true and (R) is the correct explanation of (A)
Show answer and explanation
Correct answer: (c) (A) is true but (R) is false
Explanation
(A) is true and (R) is false.
- (A): carboxylic acids do not give the usual tests for the carbonyl group (with 2,4-DNP, Tollens' or Fehling's reagent) that aldehydes and ketones give.
- (R): the reason is not that the carbon is electron-deficient. An electron-deficient carbon would be more open to attack by nucleophiles, not less. In the –COOH group, the lone pairs of the –OH oxygen are shared with the C=O by resonance, which makes the carbonyl carbon less electron-deficient, so it reacts less with nucleophiles.