Question

In which of the following reactions product will be aldehyde?

• A.
• B. $C{H}_{3}C{H}_{2}C{H}_{2}OH\stackrel{\text{PCC in}C{H}_{2}C{l}_2}{\to }$
• C. $C{H}_3-C\equiv CH\underset{HgS{O}_4}{\overset{H_{2}S{O}_4}{\to }}$
• D. Both (a) and (b)

Answer 1

The correct option is D Both (a) and (b)

(a) Ozonolysis of alkenes involves the addition of an ozone molecule to an alkene, to form an ozonide. Formed ozonide undergoes cleavage by $Zn/H_{2}O$ to give smaller oxidised product. but-2-ene undergo ozonolysis to give ethanal.(b) PCC(Pyridinium chlorochromate) is a mild oxidizing agent. It converts $1^o$ alcohols to aldehydes and $2^o$ alcohols to ketones, but is not strong enough to convert primary alcohols to carboxylic acids.
$C{H}_{3}C{H}_{2}C{H}_{2}OH\stackrel{\text{PCC in}C{H}_{2}C{l}_2}{\to }$
(c) The hydration of propyne gives acetone.
$C{H}_3-C\equiv CH\underset{HgS{O}_4}{\overset{H_{2}S{O}_4}{\to }}C{H}_{3}COC{H}_3$
Hence option (a) and (b) will give aldehyde.