Question

$C{H}_{3}CHO$ and $C_6{H}_{5}C{H}_{2}CHO$ can be distinguised chemically by :

• A. Benedict test
• B. Iodoform test
• C. Tollen's reagent test
• D. Fehling's solution test

Answer 1

Answer: (B)

$C{H}_{3}CHO$ and $C_6{H}_{5}C{H}_{2}CHO$ react with Tollen's reagent, Fehlings solution and Benedict's solution.
But $C{H}_{3}CHO$ reacts with $NaOH$ and $I_2$ to give yellow crystals of Iodoform while $C_6{H}_{5}C{H}_{2}CHO$ doesn't react with it. So, iodoform test is used.
$C{H}_{3}CHO+3I_2+4NaOH⟶CH{I}_3+HCOONa+3NaI+3H_{2}O$
$C_6{H}_{5}C{H}_{2}CHO+I_2+4NaOH⟶$ No reaction.