Structures, Reactions, Uses and Properties of Carbonyl Compounds: Aldehydes, Ketones, Carboxylic Acids, Esters, Acyl Chlorides, Amides

Aldehydes

Organic compounds containing a formyl group, denoted R-CHO, where R is a hydrocarbon.
The hydrogen in the CHO group can be oxidised to form a carboxylic acid.
Aldehydes can also undergo nucleophilic addition reactions with compounds such as cyanide and hydrogen-cyanide.
Used in the fragrance and flavour industry due to their strong, often pleasant, smells, and in the manufacture of resins and plastics.

Ketones

They possess a carbonyl group in which the carbon atom is covalently bonded to an oxygen atom and this carbonyl group (>C=O) is located within the carbon chain.
Their general formula is R-CO-R’, where R and R’ are hydrocarbon groups.
Ketones are resistant to oxidation but can undergo nucleophilic addition reactions similar to aldehydes.
Used in the manufacture of drugs, resins, plastics, textiles, and in the paint and coatings industry.

Carboxylic Acids

Formed when aldehydes are oxidised; they contain a carboxyl group (-COOH).
Their general formula is R-COOH where R represents the rest of the molecule.
Can undergo esterification reaction with alcohols to yield esters.
Used in the manufacture of soaps, detergents, dyes and pharmaceuticals.

Esters

Formed from the condensation of a carboxylic acid and an alcohol in the presence of a catalyst.
Their general formula is R-COO-R’ where R is the rest of the acid molecule and R’ is the rest of the alcohol molecule.
Esterification is a reversible reaction and esters can be hydrolysed back to their respective acids and alcohols.
Used in the creation of perfumes and flavourings due to their pleasant smells, and in the production of various types of plastics.

Acyl Chlorides

Created by replacing the -OH group of a carboxylic acid with a chlorine atom.
They are very reactive and undergo substitution reactions with nucleophiles such as water, ammonia and alcohols.
Used in the production of dyes and pharmaceuticals, and in the manufacture of carboxylic acids and esters.

Amides

Formed from the reaction of acyl chlorides with amines or ammonia.
Can also be formed from a carboxylic acid and an amine or ammonia where an ester is an intermediate.
Amides are less reactive compared to acyl chlorides but can be hydrolysed to form a carboxylic acid and an amine.
Used in the production of plastics and polymers.

Properties

Aldehydes and ketones are generally more reactive than other carbonyl compounds due to the presence of a hydrogen atom, making them more prone to oxidation. They are relatively high boiling point substances due to their ability to form hydrogen bonds.
Carboxylic acids have rather high boiling points owing to the presence of two polar groups (-COOH).
Esters and acyl chlorides are typically low boiling point substances due to their inability to form hydrogen bonds.
Amides are relatively high boiling point compounds owing to the ability to form two hydrogen bonds per molecule.

This knowledge of structures, reactions, uses and properties of carbonyl compounds: aldehydes, ketones, carboxylic acids, esters, acyl chlorides, amides is an essential part of Applications of Organic Chemistry.