Carboxylic Acids

Carboxylic acids are organic compounds containing a carboxyl group (-COOH).
The carboxyl group consists of a carbonyl group (C=O) and a hydroxyl group (O-H) attached to the same carbon atom.
Carboxylic acids are named by replacing the -e at the end of the parent alkane with -oic acid e.g., ethane turns to ethanoic acid.
They are usually found as colourless liquids or white solids.
They have distinctive sour odours and are responsible for the smell of vinegar (ethanoic acid) and rancid butter (butanoic acid).

Physical Properties of Carboxylic Acids

Carboxylic acids can form hydrogen bonds due to the presence of hydrogen atoms in the -OH group, which gives them higher boiling points than similar-sized alkanes or alcohols.
The entire carboxyl group is polar due to the electronegative oxygen atoms which gives carboxylic acids the ability to dissolve in water.
Solubility in water decreases with increasing chain length beyond four carbon atoms as the non-polar hydrocarbon chain style dominates.

Carboxylic acids can undergo a variety of chemical reactions, including neutralisation, esterification and oxidation.
During neutralisation reactions, carboxylic acids react with bases to produce a salt and water.
In an esterification reaction, a carboxylic acid reacts with an alcohol in the presence of a strong acid catalyst to form an ester. This is commonly used in the production of artificial flavours and scents.
The carboxyl group can be further oxidised to form carbon dioxide, however, it typically requires strong oxidising agents.

Carboxylic acids can be corrosive and cause skin and eye irritation.
Proper safety precautions including the use of lab coats, gloves, and safety glasses should be followed whenever handling these substances.
They should always be handled by using a fume hood, as the vapours can be harmful if inhaled.

Carboxylic acids are found in a multitude of everyday substances, including vinegar (contains ethanoic acid) and citrus fruits (contains citric acid).
They are used in the production of plasticisers, detergents, pharmaceuticals and industrial chemicals.