Question

Following compounds are given
(i) $C{{H}_{3}}C{{H}_{2}}OH$
(ii) $C{{H}_{3}}COC{{H}_{3}}$
(iii) ${{(C{{H}_{3}})}_{2}}CHOH$
(iv) $C{{H}_{3}}OH$
Which of the above compounds on being warmed with iodine solution and NaOH , will give iodoform?
(a) (i), (ii) and (iv)
(b) only (i)
(c) (i), (ii) and (iii)
(d) (i) and (ii)

Answer 1

Hint: The iodoform test is given by those compounds which consist of the carbonyl compounds consisting of the methyl group or the alcohol group. Now you can easily identify the compounds from the above given compounds which will give this iodoform test.

Complete answer:
First of all, let’s discuss what is an iodoform test. In the iodoform test; the given compound is made to react with the iodine solution in the presence of a base i.e. sodium hydroxide (NaOH) which results in the formation of yellow color precipitates i.e. iodoform.
This test is given by those compounds which consists of the either $-C{{H}_{3}}$ group attached to the carbonyl carbon i.e.$-C=O$ or $-OH$ group attached to the carbonyl carbon i.e. $-C=O$.
 Now considering the statement:
In option (i), the compound $C{{H}_{3}}C{{H}_{2}}OH$, doesn’t consist of the carbonyl group. So, it will not give this iodoform test.
In option (ii), the compound $C{{H}_{3}}COC{{H}_{3}}$consists of the $-COC{{H}_{3}}$group and thus, it will give the iodoform test.
In option (iii), the compound ${{(C{{H}_{3}})}_{2}}CHOH$, doesn’t consist of the carbonyl group. So, it will not give this iodoform test.
In option (iv), the compound $C{{H}_{3}}OH$ doesn’t consist of the carbonyl group. So, it will not give this iodoform test.
So, thus from the above it is clear that only compound $C{{H}_{3}}COC{{H}_{3}}$ on being warmed with iodine solution and NaOH will give iodoform.

Hence, option (b) is correct.

Note:
The iodoform test is performed in the laboratories to check or detect the presence of the carbonyl compounds which consists of either methyl group or the alcohol group attached to the carbonyl carbon.