Question

What is the name of the following reaction?
${\text{PhCHO + (C}}{{\text{H}}_{\text{3}}}{\text{CO}}{{\text{)}}_{\text{2}}}{\text{O}}\xrightarrow{{{\text{Na(OAc}}{{\text{)}}_{\text{2}}}}}{\text{PhCH = CHC}}{{\text{O}}_{\text{2}}}{\text{H}}$
A.Oxymercuration demercuration reaction
B.Cannizzaro reaction
C.Knoevenagel’s reaction
D.Perkin reaction.

Answer 1

Hint: Aromatic: The compounds which have cycles, planar structure with conjugated $\pi $ -bonds which do the resonance in the compound which cause high stability of the compound.
Perkin reaction: It is defined as the reaction of aromatic aldehyde with acetic anhydride in presence of alkaline salt to form $\alpha ,\beta $- unsaturated aromatic acid.

Complete step by step solution:
First of all let us talk about the aromatic compounds and the reaction given in the option of the question.
Aromatic compounds: The compounds which have cycles, planar structure with conjugated $\pi $ -bonds which do the resonance in the compound which cause high stability of the compound. For example: benzene and its derivatives.
Oxymercuration demercuration reaction: In this reaction one alkene reacts with mercury ion ${\text{H}}{{\text{g}}^{{\text{2 + }}}}$ salt in presence of water or alcohol. It results in an organomercury intermediate. And when this intermediate reacts with ${\text{NaB}}{{\text{H}}_{\text{4}}}$ the final product formed is an alcohol.
Cannizzaro reaction: This is a disproportionation reaction i.e. in which the same molecule is oxidised as well as reduced, in which aldehydes reacts with concentrated potassium hydroxide and forms alcohol (reduced product of aldehyde) and carboxylic acid ( oxidised product of aldehyde).
$\alpha ,\beta $- unsaturated compounds: These are those compounds in which the carbon of the functional group is attached to the double bond or triple bond carbon.
Knoevenagel’s reaction: In this reaction aldehyde or ketone on dehydration in presence of basic amine gives $\alpha ,\beta $- unsaturated compounds i.e. may be $\alpha ,\beta $- unsaturated aldehyde, or $\alpha ,\beta $- unsaturated carboxylic acid etc.
Perkin reaction: It is defined as the reaction of aromatic aldehyde with acetic anhydride in presence of alkaline salt to form $\alpha ,\beta $- unsaturated aromatic acid.
Here in the question we are given with the reaction as ${\text{PhCHO + (C}}{{\text{H}}_{\text{3}}}{\text{CO}}{{\text{)}}_{\text{2}}}{\text{O}}\xrightarrow{{{\text{Na(OAc}}{{\text{)}}_{\text{2}}}}}{\text{PhCH = CHC}}{{\text{O}}_{\text{2}}}{\text{H}}$
In this reaction the reactants are aromatic aldehyde (benzaldehyde) and acetic anhydride and the product is $\alpha ,\beta $- unsaturated aromatic acid so it is an example of Perkin reaction.

Hence option D is correct.

Note: Functional groups: These are defined as the groups which when attached to the hydrocarbons results in a new compound having different properties. Example: aldehyde which is ${\text{ - CHO}}$, ketone which is ${\text{ - CO - }}$ , carboxylic acid ${\text{ - COOH}}$ and many more.