Deprotonised

Deprotonised is a term used in chemistry to describe an atom or molecule that has lost a proton. A proton is a positively charged subatomic particle found in the nucleus of an atom. When an atom or molecule loses a proton, it becomes negatively charged. This process is called deprotonation and is the reverse of protonation, where an atom or molecule gains a proton.

Deprotonation is a fundamental concept in acid-base chemistry. Acids are substances that can donate protons, while bases are substances that can accept protons. When an acid dissolves in water, it donates a proton to a water molecule, forming a hydronium ion and a deprotonised conjugate base. For example, hydrochloric acid (HCl) deprotonises in water to form a hydronium ion (H3O+) and a chloride ion (Cl-). The chloride ion is the deprotonised form of HCl.

The term deprotonised is often used in the context of organic chemistry, particularly when discussing enolates and other reactive intermediates. Enolates are formed when a base removes a proton from an alpha-carbon adjacent to a carbonyl group. The resulting carbanion is a nucleophile and can participate in various reactions, such as alkylation and aldol condensation.

Deprotonised species can also be found in biological systems. For instance, many enzymes function by deprotonising substrates or cofactors, facilitating biochemical reactions. The acidity and basicity of amino acid residues in proteins are also influenced by their deprotonised state, which can affect protein structure and function. Understanding deprotonisation is crucial for comprehending a wide range of chemical and biological processes.