Question

$CH _{3} CHO$ and $C _{6} H _{5} CH _{2} CHO$ 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)

$CH _{3} CHO$ and $C _{6} H _{5} CH _{2} CHO$ react with Tollen's reagent, Fehlings solution and Benedict's solution.
But $CH _{3} CHO$ reacts with $NaOH$ and $I _{2}$ to give yellow crystals of Iodoform while $C _{6} H _{5} CH _{2} CHO$ doesn't react with it. So, iodoform test is used.
$CH _{3} CHO +3 I _{2}+4 NaOH \longrightarrow CHI _{3}+ HCOONa +3 NaI +3 H _{2} O$
$C _{6} H _{5} CH _{2} CHO + I _{2}+4 NaOH \longrightarrow$ No reaction.