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प्रश्न
Write a note on the self oxidation-reduction reaction of an aldehyde with a suitable example.
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उत्तर
Cannizaro’s Reaction:-
(a) This is a characteristic reaction of those aldehydes which do not contain α -hydrogen atom.
(b) When such aldehydes are heated with concentrated alkali solutions like NaOH or KOH then simultaneous oxidation-reduction takes place.
(c) Out of two molecules of aldehyde one molecule, gets oxidised to form sodium or potassium salt of carboxylic acid and the second molecule is reduced to form corresponding primary alcohol.
(d) It is an auto oxidation-reduction reaction under the influence of base
(e) Formaldehyde and benzaldehyde undergo Cannizaro’s reaction as they do not contain α -hydrogen atom.
e.g.
\[\ce{\underset{\text{Formaldehyde(40-50%)}}{2H-CHO +NaOH}->[Redox][Reaction]\underset{\text{Sodium formate}}{HCOONa}+\underset{\text{Methanol}}{CH3}- OH}\]
\[\ce{\underset{\text{Benzaldehyde(50%)}}{2C6H5CHO +NaOH}->[Redox][Reaction]\underset{\text{Benzylalcohol}}{C6H5CH2OH} +\underset{\text{Sodiumbenzoate}}{C6H5COONa}}\]
(f) Acetaldehyde does not give this reaction since it contains α -Hydrogen atoms.
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संबंधित प्रश्न
Write the chemical equation for the reaction involved in Cannizzaro reaction.
Describe the following:
Cannizzaro reaction
Write the product(s) in the following reactions
Complete the following reactions:
Write the chemical equations to illustrate the following name reactions:
Aldol condensation
Write the product formed when p-nitro chlorobenzene is heated with aqueous NaOH at 443K followed by acidification?
complete the following reaction:
complete the following reaction:
\[\begin{array}{cc}
\phantom{...}\ce{CH3} \\
| \\
\phantom{.................}\ce{CH3-CH-COOH ->[(i) Br2/Red P4][(ii)H2O]}
\end{array}\]
Complete the following reaction:
The products obtained in the Cannizzaro reaction are
The key step in cannizzaro reaction in the inter molecular shift qf
What happens when methanal undergoes cannizzaro reaction?
\[\begin{array}{cc}
\ce{D}\phantom{........................}\\
|\phantom{.........................}\\
\ce{2D - C = O + OH^- ->[Cannizzaro] X and Y}
\end{array}\]
(Y is alcohol, D is deuterium)
X and Y will have the structure:
Which of the following does not give Cannizzaro reaction?
Convert the following:
Benzene to m-nitrobenzaldehyde
Write the chemical reaction involved in Cannizzaro reaction of methanal.
Benzaldehyde can be prepared by the hydrolysis of:
Which product is formed when the compound benzaldehyde is treated with concentrated aqueous KOH solution?
