When acetaldehyde Is treated with dilute NaOH the following reaction is observed. 2 CH 3 - CHO → dil . NaOH CH 3 - CH | OH - CH 2 - CHO What are the functional groups in the product?

There are two functional groups in the product, which are aldehyde and an alcohol i.e. - CHO and - OH respectively. Aldol condensation occurs in aldehydes having α - hydrogen with a dilute base to give β - hydroxy aldehydes called aldols. This reaction is most commonly known as aldol condensation.

When acetaldehyde Is treated with dilute NaOH the following reaction is observed. 2 CH 3 - CHO → dil . NaOH CH 3 - CH | OH - CH 2 - CHO Will there be another product formed during the same reaction ? (Deduce the answer by doing atomic audit of reactant and product)

This is aldol condensation, it is the reaction when two aldehydes that are the same or different react together in the presence of dilute alkali to form a product intermediate that has an aldehyde and alcohol, called aldol. This aldol on dehydration gives α , β - unsaturated carbonyl compounds. No other product can be formed in the same reaction.

When acetaldehyde Is treated with dilute NaOH the following reaction is observed. 2 CH 3 - CHO → dil . NaOH CH 3 - CH | OH - CH 2 - CHO Is this an addition reaction or condensation reaction?

2 CH 3 - CHO → dil . NaOH CH 3 - CH | OH - CH 2 - CHO This is aldol reaction and formation of aldol is an example of addition reaction. Aldol formed from aldehyde having α - hydrogens undergoes subsequent elimination of water on warming, giving rise to α , β - unsaturated aldehyde.

Observe the following reaction. Will this reaction give a mixture of products like a cross aldol reaction?

No, since benzaldehyde does not have a α - hydrogen atom, it will not undergo self-aldol condensation. The reaction between benzaldehyde and acetophenone undergoes cross-aldol condensation in presence of dil. NaOH. In this reaction, benzaldehyde has no alpha hydrogen, but acetophenone has alpha hydrogen, so it undergoes aldol condensation form β-hydroxy ketone. Furthermore, dehydration leads to the formation of the α, β – unsaturated ketone.

Write short notes on the stephen reaction.

Alkyl nitriles undergo reduction with the help of tin (II) chloride and hydrochloric acid and form an intermediate imine salt which undergoes hydrolysis with water, giving the final result as aldehydes. R − CN + 2 [ H ] → SnCl 2 / dil . HCl R − CH = NHHCl → H 2 O R − CHO + NH 4 Cl

Explain the following reaction: Cannizzaro reaction

Cannizzaro's reaction: The self oxidation-reduction (disproportionation) reaction of aldehydes which do not have α -hydrogen atom, on treatment with concentrated alkali is known as the Cannizzaro's reaction. In this reaction, two molecules of aldehydes participate where one is reduced to alcohol and the other is oxidised to carboxylic acid. For example, when methanal is treated with concentrated potassium hydroxide, methanol and potassium methanoate are produced. 2 HCHO → Con . KOH CH 3 OH + HCOOK