question_answer

Benzaldehyde undergo Claisen condensation to give cinnamaldehyde on reaction with \[[\alpha ]\] in presence of base, \[[\alpha ]\]and degree of unsaturation in cinnamaldehyde is

A)  formaldehyde, 3            

B)  acetaldehyde, 6        

C)  crotonaldehyde, 4         

D)  propanaldehyde, 6

Correct Answer: B

Solution :

 Idea This problem includes concept of Claisen condensation. Claisen condensation The reaction between benzaldehyde and acetaldehyde leads to formation of cinnamaldehyde in presence of base as follows Molecular formula \[={{C}_{9}}{{H}_{8}}O\] Degree of un saturation \[u=(C+1)-\frac{H}{2}+\frac{N}{2}\] \[u=(9+1)-\frac{8}{2}=10-4=6\] TEST Edge Problem on nucleophilic addition of Grignard reagent or organotithium reagent to carbonyl compound are asked generally, students are allowed to study these including stereochemistry of compound.