Question

Which of the following does not give iodoform:
A. Acetic acid
B. Lactic acid
C. Actophenone
D. Propionic acid

Answer 1

To solve this question we should know about the term iodoform test and what happens in the test. After the test we will mention the result of the groups that are given and in this case the result is the formation of yellow precipitate. This test is useful in detecting the presence of the compound with the methyl ketone in them. This question contains multiple correct options.

Complete Solution :
The iodoform test is the reaction of the bases and the iodine with the methyl ketones or the compound with methyl ketones in them.
- This test is so much reliable that it is used widely to detect the presence of methyl ketones present in any given compound. The result of the iodoform test is the formation of yellow precipitate and the presence of yellow precipitate declares the presence of methyl ketonic group in the compound.
- This can also be the case when we are testing for the specific secondary alcohols that contain at least one methyl group present at the alpha position.
- Now, in this test if any kind of acid reacts in the reaction then it tends to convert into an Acid-Base reaction and as we know that acid and bases will ultimately make the salt and deny the result of the precipitate. Hence, it will fail the test for methyl ketone group.
- In the question we can see that there are two carboxylic acids that are acetic acid and propionic acid and therefore they will fail the iodoform test.
So, the correct answer is “Option A and D”.

Note: Lactic acid and the acetophenone shows the iodoform test as they give yellow precipitate as a result. And if we will take the case of carboxylic acid with the methyl ketonic group then the iod- oform test will show no result because here the acid-base reaction will be more feasible than any other type of reaction.