Question

Iodoform can be prepared from all except

• A. ethyl methyl ketone
• B. Isopropyl alcohol
• C. 3-methyl-2-butanone
• D. Isobutyl Alcohol

Answer 1

The correct option is D

Isobutyl Alcohol

Iodoform reaction is given by methyl ketones, where the carbonyl group is connected to a methyl group on one side (at least - so acetone also gives the iodoform reaction). Also, acetaldehyde gives the iodoform test - basically we need a carbonyl group attached to a methyl group.

Also, compounds that can be oxidized to methyl ketones give this test. For example, a secondary alcohol of the form $R-CH\left(OH\right)-C{H}_3$ gets oxidized to an alkyl methyl ketone. This would also give the iodoform test. From the options, the following will all give the iodoform test:

Isobutyl alcohol is a primary alcohol.