Question

In the following reaction sequence, the compound $J$ is an intermediate.
$I\underset{C{H}_{3}COONa}{\overset{(C{H}_{3}CO{)}_{2}O}{\to }}J\underset{(ii)SOC{l}_2,(iii)\text{anhyd.}AlC{l}_3}{\overset{(i)H_2,Pd/C}{\to }}J$
$J\left(C_9{H}_8{O}_2\right)$ gives effervescence on treatment with $NaHC{O}_3$ anda positive Baeyer's test.
The compound $I$ is

• A.
• B.
• C.
• D.

Answer 1

Answer: (A)

In the given reaction, an aromatic aldehyde is condensed with an acid anhydride (Perkin condensation) in the presence of a base to form $\alpha ,\beta -$ unsaturated acid (cinnamic acid). This gives effervescence on reaction with $NaHC{O}_3$ and positive test with Bayer's reagent ($1\%$ alkaline $KMn{O}_4)$.
$\underset{I}{Ph-CHO}\stackrel{(C{H}_{3}CO{)}_{2}OC{H}_{3}COONa}{\to }\underset{J\text{(Cinnamic acid)}}{Ph-CH=-COOH}\stackrel{NaHC{O}_3}{\to }$ Effervescence
Cinnamic acid $\underset{\text{(Bayer’s reagent)}}{\overset{1\%cold,alk;KMn{O}_4}{\to }}$ Positive