Question

Which of the following does NOT undergo haloform reaction?
A. \[C{{H}_{3}}-CH(OH)-C{{H}_{3}}\]
B. \[C{{H}_{3}}-CH(O)-C{{H}_{3}}\]
C. \[{{C}_{2}}{{H}_{5}}-CH(OH)-{{C}_{2}}{{H}_{5}}\]
D. \[C{{H}_{3}}-C(O)-{{C}_{2}}{{H}_{5}}\]

Answer 1

Hint: As the name suggests, haloform reaction is a type of reaction which will result in the form of haloforms such as chloroform, bromoform and iodoform. Compounds with the alpha methyl group gives this test.

Complete step by step answer:
Haloform test is a distinction test. This test is given by aldehydes (mainly) and ketones that contain the alpha-methyl group.

Let us draw all the compounds given in the question and check it for the ‘alpha-methyl group’.
Option (a)

The structure of the compound given in option (a) is a secondary alcohol. It does not contain the alpha-methyl group.
Therefore, it does not give a haloform test.

Option (b)

The structure of the compound given in option (b) is a secondary ketone. It contains the alpha-methyl group.
Therefore, it gives the haloform test.

Option (c)

The structure of the compound given in option (c) is a secondary alcohol. It does not contain the alpha-methyl group.
Therefore, it does not give a haloform test.

Option (d)

      

The structure of the compound given in option (d) is a secondary ketone. It does not contain the alpha-methyl group.
Therefore, it does not give a haloform test.
Therefore, the answer is – option (b).

Additional Information:
Chloroform is a colourless liquid. Bromoform is a colourless liquid with a sweet smell. Iodoform forms a pale-yellow precipitate with funky smell.

Note: The reaction in haloform takes place through the following reaction –
\[R-C(O)-C{{H}_{3}}+3{{X}_{2}}+4NaOH\to R{{X}_{3}}+C{{H}_{3}}COONa+3NaX+4{{H}_{2}}O\]
Where, X – halogen (Cl, Br, I).