๐ฟ Introduction to Aldehydes, Ketones, and Carboxylic Acids ๐
Aldehydes, ketones, and carboxylic acids are important organic compounds with distinct functional groups and diverse applications in fragrances, flavours, and pharmaceuticals. Their preparation methods, reactivity, and uses make them integral to several industries.
โ๏ธ 1. Aldehydes (Functional Group -CHO) ๐
๐งช Structure and Functional Group
- Aldehydes contain a carbonyl group (C=O) attached to a hydrogen atom and an alkyl or aryl group.
- The general formula: R-CHO.
๐ฌ Preparation of Aldehydes
- Oxidation of Alcohols:
- Primary alcohols can be oxidized to form aldehydes.
- Example: Ethanol โ Acetaldehyde.
- Hydroformylation of Alkenes:
- Alkene + CO + Hโ โ Aldehyde.
โก Reactions of Aldehydes
- Nucleophilic Addition:
- Aldehydes undergo nucleophilic addition reactions like addition of HCN to form cyanohydrin.
- Oxidation:
- Aldehydes are easily oxidized to form carboxylic acids.
- Example: Formaldehyde โ Formic acid.
๐ฌ 2. Ketones (Functional Group -CO-) ๐
๐งฌ Structure and Functional Group
- Ketones contain a carbonyl group attached to two alkyl groups.
- The general formula: R-CO-R’.
๐ฅ Preparation of Ketones
- Oxidation of Secondary Alcohols:
- Secondary alcohols are oxidized to form ketones.
- Example: Isopropanol โ Acetone (Propan-2-one).
- Friedel-Crafts Acylation:
- Aromatic compound + Acyl chloride โ Ketone.
๐ก Reactions of Ketones
- Nucleophilic Addition:
- Ketones undergo nucleophilic addition reactions like addition of HCN to form cyanohydrin.
- Reduction:
- Ketones can be reduced to secondary alcohols using reducing agents like NaBHโ.
๐งช 3. Carboxylic Acids (Functional Group -COOH) ๐ท
๐ก Structure and Functional Group
- Carboxylic acids have a carbonyl group attached to a hydroxyl group (-OH), making the -COOH group the defining feature.
- The general formula: R-COOH.
โ๏ธ Preparation of Carboxylic Acids
- Oxidation of Aldehydes:
- Aldehydes are oxidized to form carboxylic acids.
- Example: Acetaldehyde โ Acetic acid.
- Hydrolysis of Nitriles:
- Nitrile + HโO โ Carboxylic acid.
๐ฅ Reactions of Carboxylic Acids
- Acidity:
- Carboxylic acids are acidic due to the ability of the hydrogen from the hydroxyl group to dissociate.
- Example: Acetic acid โ Acetate ion + Hโบ.
- Reduction:
- Carboxylic acids can be reduced to primary alcohols using reducing agents like LiAlHโ.
๐ Uses of Aldehydes, Ketones, and Carboxylic Acids ๐
๐ Aldehydes
- Fragrances and Flavours:
- Vanillin (from vanilla), a famous aldehyde, is used in flavouring and fragrance products.
- Pharmaceuticals:
- Formaldehyde is used as a disinfectant and preservative in medicines.
๐ Ketones
- Solvents:
- Acetone is commonly used as a solvent in cleaning agents, paints, and varnishes.
- Fragrances:
- Camphor (a ketone) is used in perfumes and as an insect repellent.
๐ท Carboxylic Acids
- Food Additives:
- Acetic acid is used in the production of vinegar, which is widely used as a food preservative and flavour enhancer.
- Pharmaceuticals:
- Aspirin (acetylsalicylic acid) is a widely used analgesic and anti-inflammatory drug.
- Polymers:
- Terephthalic acid is a key ingredient in the production of polyester.
โก Conclusion โก
- Aldehydes, ketones, and carboxylic acids are versatile organic compounds with vital roles in industries ranging from pharmaceuticals to food processing.
- Their functional groups, preparation methods, and reactions are fundamental in understanding their wide applications in fragrances, flavours, and chemical processes.