Question

What is the action of hydrogen cyanide in the basic medium on \[2,4 - \]dichlorobenzaldehyde?

Answer 1

Hint: A cyanohydrin reaction is an organic chemical reaction by an aldehyde or ketone with a cyanide anion or a nitrile to form a cyanohydrin. This nucleophilic addition is a reversible reaction but with aliphatic carbonyl compounds equilibrium is in favor of the reaction products. \[2,4 - \] Dichlorobenzaldehyde will also undergo a nucleophilic addition reaction with hydrogen cyanide to form the corresponding cyanohydrin.

Complete answer:
Cyanide ion from hydrogen cyanide acts as a nucleophile and undergoes nucleophilic addition reaction to form the corresponding cyanohydrin. \[2,4 - \] Dichlorobenzaldehyde will also undergo nucleophilic addition reaction with hydrogen cyanide to form the corresponding cyanohydrin.
$RCH = O + H - C \equiv N \to RCH(OH)CN$
Hydrogen cyanide reacts with benzaldehyde in a manner typical of the aliphatic aldehydes to give the corresponding cyanohydrin, mandelonitrile, hydrolysis of which gives mandelic acid.

Additional information:
Hydrogen Cyanide is a highly toxic conjugate acid of a cyanide that is used as a chemical weapon agent. It is characterized as a colorless gas or liquid with a strong pungent odor that causes irritation of the eyes and respiratory tract, as well as toxic systemic effects. Cyanide prevents the cells of the body from using oxygen. When this happens, the cells die. Cyanide is more harmful to the heart and brain than to other organs because the heart and brain use a lot of oxygen.

Note:
The cyanide source can be potassium cyanide, sodium cyanide or trimethylsilyl cyanide. With aromatic aldehydes such as benzaldehyde, the benzoin condensation is a competing reaction. The reaction is used in carbohydrate chemistry as a chain extension method for example that of $D - $xylose.