Bihar Board - Class 12 Chemistry - Chapter 12: Aldehydes Ketones and Carboxylic acids Handwritten Notes

This chapter deals with the important classes of organic compounds known as aldehydes, ketones, and carboxylic acids. These compounds play a significant role in both organic chemistry and everyday life. Aldehydes and ketones are carbonyl compounds, where the carbonyl group (C=O) is the central functional group. In aldehydes, the carbonyl group is attached to at least one hydrogen atom, whereas in ketones, it is attached to two carbon atoms. Carboxylic acids are organic compounds containing the carboxyl group (-COOH), which is responsible for their acidic properties. These compounds are essential in the preparation of various industrial chemicals, pharmaceuticals, and food products.

Key Points:

1. Aldehydes:

   • Aldehydes contain a carbonyl group (C=O) with at least one hydrogen atom attached to the carbonyl carbon.
   • General formula: R-CHO (where R can be a hydrogen atom or an alkyl group).
   • Examples: Formaldehyde (CH₂O), Acetaldehyde (CH₃CHO).
   • Aldehydes are highly reactive and are used in the production of plastics, disinfectants, and preservatives.

2. Ketones:

   • Ketones also contain a carbonyl group, but both sides of the carbonyl carbon are attached to carbon atoms.
   • General formula: R-CO-R' (where R and R' are alkyl or aryl groups).
   • Examples: Acetone (CH₃COCH₃), Benzophenone (C₆H₅COC₆H₅).
   • Ketones are commonly used as solvents in industrial processes and in the formulation of perfumes and cosmetics.

3. Carboxylic Acids:

   • Carboxylic acids contain a carboxyl group (-COOH), which is a combination of a carbonyl group and a hydroxyl group.
   • General formula: R-COOH.
   • Examples: Acetic acid (CH₃COOH), Benzoic acid (C₆H₅COOH).
   • Carboxylic acids are known for their sour taste and acidic properties. They are used in the manufacturing of vinegar, soaps, and as preservatives.

4. Preparation Methods:

   • Aldehydes can be prepared by oxidation of primary alcohols.
   • Ketones are often prepared by oxidation of secondary alcohols.
   • Carboxylic acids can be obtained by oxidation of aldehydes or through the hydrolysis of nitriles.

5. Reactions:

   • Aldehydes undergo nucleophilic addition reactions, reduction, and can be oxidized to carboxylic acids.
   • Ketones undergo nucleophilic addition reactions but are less reactive than aldehydes.
   • Carboxylic acids undergo reactions such as esterification, reduction to alcohols, and decarboxylation.

6. Uses:

   • Aldehydes are used in the production of resins, paints, and as disinfectants.
   • Ketones are widely used as solvents, in perfumes, and in pharmaceuticals.
   • Carboxylic acids are used in the manufacturing of soaps, detergents, food additives, and pharmaceuticals.

Conclusion:

Aldehydes, ketones, and carboxylic acids are fundamental organic compounds that play crucial roles in both industrial applications and everyday products. The key difference between aldehydes and ketones lies in the structure of the carbonyl group, while carboxylic acids are characterized by the carboxyl group. Their diverse chemical reactions, including oxidation, reduction, and esterification, make them versatile in a wide range of chemical processes. Understanding these compounds is essential in fields like organic synthesis, pharmaceuticals, and the production of consumer goods.