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}{\mathop{C{{H}_{3}}C{{H}_{2}}OH}}\,+4{{I}_{2}}+6NaOH\xrightarrow[{}]{\Delta } $ $ \underset{iodoform}{\mathop{CH{{I}_{3}}}}\,+HCOONa+5NaI+5{{H}_{2}}O $ $ \underset{2-bu\tan ol}{\mathop{C{{H}_{3}}C{{H}_{2}}\underset{\begin{smallmatrix} | \\ OH \end{smallmatrix}}{\mathop{CH}}\,-C{{H}_{3}}}}\,+4{{I}_{2}}+6NaOH\xrightarrow[{}]{\Delta } $ $ \underset{iodoform}{\mathop{CH{{I}_{3}}}}\,+C{{H}_{3}}C{{H}_{2}}COONa+5NaI+5{{H}_{2}}O $ $ \underset{ethanal}{\mathop{C{{H}_{3}}CHO}}\,+3{{I}_{2}}+NaOH\xrightarrow{\Delta }\underset{iodoform}{\mathop{CH{{I}_{3}}}}\, $ $ +HCOONa+3HI $