Notes On Aldehydes And Ketones: Introduction - CBSE Class 12 Chemistry
Aldehydes and ketones are organic compounds that contain Carbon - Oxygen double bonds, that is, the carbonyl group as a functional group. They have the general molecular formula - CnH2nO. Aldehydes and ketones closely resemble each other in most of their chemical properties. Hence, they are often collectively referred to as carbonyl compounds. Even though aldehydes and ketones differ in the nature of the groups that are attached to the carbonyl group. In aldehydes one of the two available valencies of the carbonyl group carbon is essentially satisfied by an H-atom, and the other by a hydrogen atom an alkyl group (or) an aryl group. Hence, the general formula for aldehydes is In ketones, the two valencies of the carbonyl group are satisfied by two alkyl (or) aryl groups, R and R|, which may be the same or different. If R and R| represent the same group, then the ketone is called a simple ketone. If R and R| are different, then the ketone is called a mixed ketone. The general formula for ketones is Due to thie difference in the nature of the groups attached to the carbonyl group in aldehydes and ketones, their reactivity is different. Ex: Aldehydes oxidise with ease as compared to ketones. Aldehydes and ketones both find significance in several biochemical processes. Ex: Glucose, a poly hydroxy aldehyde is the chief product in photosynthesis. Respiration, takes place via the combustion of glucose, is associated with the liberation of energy. Thus, it is the ultimate source of energy in plants and animals. Uses: Formaldehyde is used to prepare Bakelite, urea formaldehyde glues and other polymeric products. Acetaldehyde is chiefly used as starting material for the synthesis of acetic acid, ethyl acetate, drugs and polymers. Benzaldehyde is used in the perfume and dye industries..

#### Summary

Aldehydes and ketones are organic compounds that contain Carbon - Oxygen double bonds, that is, the carbonyl group as a functional group. They have the general molecular formula - CnH2nO. Aldehydes and ketones closely resemble each other in most of their chemical properties. Hence, they are often collectively referred to as carbonyl compounds. Even though aldehydes and ketones differ in the nature of the groups that are attached to the carbonyl group. In aldehydes one of the two available valencies of the carbonyl group carbon is essentially satisfied by an H-atom, and the other by a hydrogen atom an alkyl group (or) an aryl group. Hence, the general formula for aldehydes is In ketones, the two valencies of the carbonyl group are satisfied by two alkyl (or) aryl groups, R and R|, which may be the same or different. If R and R| represent the same group, then the ketone is called a simple ketone. If R and R| are different, then the ketone is called a mixed ketone. The general formula for ketones is Due to thie difference in the nature of the groups attached to the carbonyl group in aldehydes and ketones, their reactivity is different. Ex: Aldehydes oxidise with ease as compared to ketones. Aldehydes and ketones both find significance in several biochemical processes. Ex: Glucose, a poly hydroxy aldehyde is the chief product in photosynthesis. Respiration, takes place via the combustion of glucose, is associated with the liberation of energy. Thus, it is the ultimate source of energy in plants and animals. Uses: Formaldehyde is used to prepare Bakelite, urea formaldehyde glues and other polymeric products. Acetaldehyde is chiefly used as starting material for the synthesis of acetic acid, ethyl acetate, drugs and polymers. Benzaldehyde is used in the perfume and dye industries..

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