Question

Which compound among the following give/s positive iodoform test?
1. Ethanol 2. Ethanal 3. 1-butanol 4. 2-butanol 5. Phenyl ethanal

• A. 1, 2 and 5
• B. 1, 3 and 4
• C. 1, 2 and 3
• D. 2, 4 and 5
• E. 1, 2 and 4

Answer 1

Answer: (E)

Carbonyl compounds having $C{H}_{3}CO$ group and alcohols having $C{H}_{3}CH(OH)$ group undergo iodoform reaction. $\underset{ethanol}{C{H}_{3}C{H}_{2}OH}+4I_2+6NaOH\stackrel{\Delta }{\to }$ $\underset{iodoform}{CH{I}_3}+HCOONa+5NaI+5H_{2}O$ $\underset{2-bu\tan ol}{C{H}_{3}C{H}_2\underset{\begin{array}{c}|\\ OH\end{array}}{\mathrm{CH}}-C{H}_3}+4I_2+6NaOH\stackrel{\Delta }{\to }$ $\underset{iodoform}{CH{I}_3}+C{H}_{3}C{H}_{2}COONa+5NaI+5H_{2}O$ $\underset{ethanal}{C{H}_{3}CHO}+3I_2+NaOH\stackrel{\Delta }{\to }\underset{iodoform}{CH{I}_3}$ $+HCOONa+3HI$