MCQ
$CH_3CHO$ and $C_6H_5CH_2CHO$ can be distinguished chemically by
  • A
    Benedict's test
  • Iodoform test
  • C
    Tollen's reagent test
  • D
    Fehling's solution test

Answer

Correct option: B.
Iodoform test
b
$\mathrm{CH}_{3} \mathrm{CHO}$ and $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CHO}$ are aliphatic aldehydes and hence react with Tollen's reagent,

Febling-solution and Benedict solution. These reagents cannot be used to distinguish them

$C H_{3} C H O$ reacts with $N a O H$ and $I_{2}$ to form yellow crystalline iodoform while $C_{6} H_{5} C H_{2} C H O$

does not react with it. $\mathrm{CH}_{3} \mathrm{CHO}+3 \mathrm{I}_{2}+4 \mathrm{NaOH} \longrightarrow $$\mathrm{CHI}_{3}$ (Yellow crystalline ppt) $ +3 \mathrm{NaI}+3 \mathrm{H}_{2} \mathrm{O}$

$C_{6} H_{5} C H_{2} C H O+3 I_{2}+4 N a O H \rightarrow N$ oreaction

$\therefore$         lodoform test can be used to distinguish between $C H_{3} C H O$ and $C_{6} H_{5} C H_{2} C H O$

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