Carboxylic acids

Need to know

What you need to know

• **Nomenclature:** To name a carboxylic acid, find the longest carbon chain containing the carboxyl group. Replace the '-e' from the corresponding alkane name with the suffix '-oic acid'.
• **Examples:** Methane becomes methanoic acid ($HCOOH$), ethane becomes ethanoic acid ($CH_3COOH$), propane becomes propanoic acid ($CH_3CH_2COOH$).
• **Structure:** The carboxyl group is planar due to the $sp^2$ hybridisation of the carbonyl carbon, which influences its reactivity and physical properties.

Explanation

The Acid Test: Understanding Carboxylic Acids

1. R–COOH: The carboxyl group consists of a carbonyl group (C=O) and a hydroxyl group (–OH) on the same carbon atom.
2. Carboxylic acids are weak acids, meaning they only partially dissociate in water to release H⁺ ions, with a typical Ka value around 10⁻⁵.
3. They undergo characteristic reactions, such as forming a salt and water with bases, or producing CO₂ gas with carbonates.
4. Strong intermolecular hydrogen bonds lead to high boiling points, often forming dimers which effectively double their molecular mass.