How are ketones and aldehydes related in structure and reactivity?

Ketones and aldehydes are related as they both contain a carbonyl group, but differ in their reactivity and structure.

Ketones and aldehydes are two types of organic compounds that are categorised under the family of carbonyl compounds. They both contain a carbonyl group (C=O), which is a carbon atom double-bonded to an oxygen atom. However, their structures differ in terms of the positioning of the carbonyl group. In aldehydes, the carbonyl group is always at the end of the carbon chain, whereas in ketones, the carbonyl group is found in the middle of the carbon chain. This difference in structure is what gives rise to their different reactivities.

In terms of reactivity, aldehydes are generally more reactive than ketones. This is because aldehydes have a hydrogen atom attached to the carbonyl group, making them more susceptible to nucleophilic attack. On the other hand, ketones have two alkyl groups attached to the carbonyl carbon, which creates a steric hindrance that reduces their reactivity.

Furthermore, the presence of the hydrogen atom in aldehydes allows them to undergo oxidation reactions to form carboxylic acids. Ketones, however, cannot be further oxidised under normal conditions due to the absence of the hydrogen atom. This is another key difference in their reactivity.

In summary, while ketones and aldehydes share the common feature of a carbonyl group, their structural differences lead to distinct reactivity patterns. Aldehydes, with their carbonyl group at the end of the carbon chain and an attached hydrogen atom, are generally more reactive and can undergo further oxidation. Ketones, with their carbonyl group in the middle of the carbon chain and two attached alkyl groups, are less reactive and resistant to further oxidation.