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KCET 2014 Chemistry Solved Paper

Question : 44 of 60

Marks: +1, -0

Iodoform reaction is answered by all, except

$\mathrm{CH}_3\mathrm{CHO}$
$\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2\mathrm{OH}$
$\mathrm{CH}_3 - \underset{\mathrm{OH}}{\underset{\vert}{\mathrm{C}}}\mathrm{H} - \mathrm{CH}_2 - \mathrm{COOH}$
$\mathrm{CH}_3 - \mathrm{CH}_2 - \mathrm{OH}$

Solution:

For alcohols secondary and tertiary alcohols gives iodoform reaction and ethanol is the only primary alcohol which gives iodoform reaction, therefore, propanol will not give iodoform reaction.

(1)

\underset{\text{Acetaldehyde}}{\mathrm{C}_{3}\mathrm{CHO}}+3\mathrm{NaOI} \rightarrow \underset{\text{Yellow ppt}}{\mathrm{CHI}_{3}}+\mathrm{HCOONa}+2\mathrm{NaOH}

(2)

\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{OH}+\mathrm{NaOI} \xrightarrow[\mathrm{I}_2]{\mathrm{NaOH}}

do not give iodoform reaction.

(3)

\mathrm{CH}_3-\overset{\mathrm{OH}}{\overset{\vert}{\underset{\mathrm{H}}{\mathrm{C}}}}-\mathrm{CH}_2\mathrm{COOH} \xrightarrow{\mathrm{NaOI}} \underset{\text{Yellow ppt.}}{\mathrm{CHI}_3} + \overset{\mathrm{O}}{\overset{\parallel}{\underset{\mathrm{NaOC}}{\mathrm{C}}}}\mathrm{CH}_2\mathrm{COOH}

\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH} \xrightarrow[\mathrm{I}_2]{\mathrm{NaOH}} \mathrm{CH}_{3}\mathrm{CHO} + \mathrm{NaI} + \mathrm{H}_{2}\mathrm{O}

\mathrm{CH}_3\mathrm{CHO} + 3\mathrm{NaOI} \rightarrow \underset{\text{Yellow ppt.}}{\mathrm{CHI}_3} + \mathrm{HCOONa} + 2\mathrm{NaOH}

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