SUBSTITUTION REACTION Meaning and
Definition
-
A substitution reaction refers to a type of chemical reaction in which one atom or a group of atoms within a molecule is replaced by another atom or group of atoms. This reaction typically takes place between molecules containing a specific functional group, resulting in the replacement of one atom or group at a particular site in the molecule's structure by a different atom or group.
Substitution reactions are commonly observed in organic chemistry, where a new atom or group of atoms takes the place of an existing atom or group. These reactions can occur spontaneously or be facilitated by a catalyst, such as a transition metal, to increase the reaction rate.
There are different types of substitution reactions, including nucleophilic substitution reactions and electrophilic substitution reactions. In a nucleophilic substitution reaction, a nucleophile, which is an electron-rich species, replaces a leaving group through the donation of a pair of electrons. Conversely, in an electrophilic substitution reaction, an electrophile, which is an electron-deficient species, substitutes a hydrogen atom or another group in a molecule by accepting a pair of electrons.
The substitution reaction concept is fundamental in understanding various chemical processes, such as organic synthesis, drug development, and biochemical transformations. These reactions allow chemists to selectively modify specific parts of a molecule, leading to the creation of new compounds with desired properties and functions.
Etymology of SUBSTITUTION REACTION
The term "substitution reaction" has its roots in the Latin word "substitutio". "Substitutio" means "a placing under" or "substituting one thing for another". This Latin term later influenced the Middle French word "substitucion" and the Old English word "substytucioun". Over time, the term evolved and is now used in chemistry to describe a reaction where one atom or group of atoms in a molecule is replaced by another atom or group of atoms.
