Question

The product formed in aldol condensation is:
A.An alpha, beta unsaturated ester
B.A beta hydroxy acid
C.A beta hydroxy aldehyde or beta hydroxy ketone
D.An alpha hydroxy aldehyde or alpha hydroxy ketone

Answer 1

Hint: When two molecules of carbonyl compounds (aldehydes or ketones) containing an alpha hydrogen, atom treated with base like sodium hydroxide a beta hydroxy aldehyde or beta hydroxy ketone is formed which is known as aldol. This reaction is known as aldol condensation.

Complete answer:
Chemical compounds are classified based on the functional group present in them. The chemical compounds containing a carbonyl group \[\left( {C = O} \right)\] are known as carbonyl compounds. Aldehydes and ketones belong to carbonyl compounds.
When two molecules of aldehyde or ketone containing an alpha hydrogen atom are treated with a base like sodium hydroxide or potassium hydroxide, the product formed is a beta hydroxy aldehyde or beta hydroxy ketone.
Let us consider an example of acetaldehyde. Two molecules of acetaldehyde treated with base forms the product as follows:
\[2C{H_3}CHO\xrightarrow{{O{H^ - }}}C{H_3} - CH\left( {OH} \right) - C{H_2} - CHO\]
As the hydroxy group is at the beta position to the aldehyde. The product was named as beta hydroxy aldehyde and simply known as aldol. This reaction is known as aldol condensation.
When two molecules of ketone were taken in presence of base then the product will be beta hydroxy ketone.
The product formed in aldol condensation is beta hydroxy aldehyde or beta hydroxy ketone.
Hence option C is the correct answer.

Note:
The aldehydes and ketones taken must have an alpha hydrogen atom as the carbonyl compounds without alpha hydrogen atoms undergo Cannizzaro reaction and form products like sodium salt of carboxylic acid and alcohol. Thus, alpha hydrogen containing carbonyl compounds will only give aldol condensation.