Which of the following compound(s) on being warmed with \(I_2\) solution and \(NaOH\), will give iodoform?
A. \(CH_3CH_2OH\)
B. \(CH_3-CO-CH_3\)
C. \(CH_3-CHOH-CH_3\)
D. \(CH_3OH\)
Choose the correct option from the ones given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, B, C only
The iodoform test (\( \ce{I2} \) + NaOH, i.e. NaOI) picks out a CH3CO– group, or a CH3CH(OH)– group that NaOI first oxidises to one:
\( \ce{CH3COCH3 + 3NaOI -> CHI3 + CH3COONa + 2NaOH} \)
\( \ce{CH3CH2OH + NaOI -> CH3CHO + NaI + H2O} \), then \( \ce{CH3CHO + 3NaOI -> CHI3 + HCOONa + 2NaOH} \)
(A) \( \ce{CH3CH2OH} \) — has \( \ce{CH3CH(OH)} \)– (with R = H); oxidised to \( \ce{CH3CHO} \), which gives iodoform. Yes.
(B) \( \ce{CH3COCH3} \) — a methyl ketone. Yes.
(C) \( \ce{CH3CHOHCH3} \) — has \( \ce{CH3CH(OH)} \)–; oxidised to acetone. Yes.
(D) \( \ce{CH3OH} \) — has no \( \ce{C-CH3} \) group; oxidation gives HCHO, which does not give iodoform. No.
NCERT (2026-27 edition):
Oxidation of Methyl Ketones by Haloform Reaction – …
