Definition of the word double decomposition

The term "double decomposition" originated in organic chemistry to describe a type of chemical reaction that involves the exchange of functional groups between two reactant molecules to form new products. This term was coined by the French chemist Charles Friedel and his compatriot Arthur Crafts in the late 19th century. In a double decomposition reaction, two reactant molecules that each contain a functional group undergo a simultaneous replacement of these groups to form two new products. For example, in the reaction between benzoic acid (C₆H₅COOH) and chloroethane (C₂H₃Cl), the deprotonated benzoic acid (C₆H₅COO^-) and chloroethanol (C₂H₅O⁻) separately exchange their protonic and chloride functional groups, respectively, to create benzyl chloride (C₆H₅CH₂Cl) and sodium benzoate (NaC₆H₅COO^-). The concept of "double decomposition" has been adopted by related fields such as biochemistry and linguistics to describe similar exchanges and transformations. However, in chemistry, it is still widely used to refer to the process by which two functional groups swap places in organic reactions, signifying a rich history and continued importance in understanding the mechanisms of organic synthesis.