Practicing Success

Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Haloalkanes and Haloarenes

Question:

Which of the following will not give iodoform test?

Options:

ethanal

benzyl alcohol

ethanol

isopropyl alcohol

Correct Answer:

benzyl alcohol

Explanation:

The iodoform test is a chemical test used to detect the presence of methyl ketone or acetaldehyde. The test is based on the oxidation of the compound to form a triiodomethane (iodoform) precipitate.

The compounds that will give a positive iodoform test are those that contain a methyl ketone group \((CH_3CO-)\) or acetaldehyde \((CH_3CHO)\). Ethanol \((CH_3CH_2OH)\) can also give a positive iodoform test, because it can be oxidized to acetaldehyde.

Benzyl alcohol \((C_6H_5CH_2OH)\) does not contain a methyl ketone group, so it will not give a positive iodoform test.

Here is a table of the compounds and their expected results with the iodoform test:

Compound

Expected Result

Ethanal

Positive

Ethanol

Positive

Isopropyl alcohol

Positive

Benzyl alcohol

Negative