ELECTROPHILIC ADDITION Meaning and
Definition
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Electrophilic addition is a chemical reaction in which an electrophile, a positively charged or electron-deficient species, reacts with a nucleophile, an electron-rich species, resulting in the addition of new atoms to a molecule. This reaction occurs primarily in unsaturated compounds, such as alkenes or alkynes, where there is a presence of a double or triple bond. The electrophile is attracted to the electron-rich π bonds in the substrate.
During electrophilic addition, the double or triple bond is broken, and new sigma bonds are formed by the addition of atoms or groups to the substrate. The electrophile attacks one of the carbon atoms involved in the π bond, resulting in the formation of a carbocation intermediate. This intermediate is highly reactive and can further react with a nucleophile to complete the addition.
The reaction proceeds through a two-step mechanism. In the first step, the electrophilic attack occurs, breaking the π bond and producing a carbocation. In the second step, the nucleophile attacks the carbocation to create a new sigma bond. The overall result is the addition of atoms or groups across the original double or triple bond.
Electrophilic addition reactions are widely used in organic chemistry to synthesize a variety of compounds. They are highly versatile and can be utilized to introduce diverse functional groups to molecules, allowing the modification of their chemical and physical properties. Electrophilic addition is a fundamental concept in understanding organic reactions and plays a crucial role in the synthesis of many important compounds, including pharmaceuticals and materials.
Etymology of ELECTROPHILIC ADDITION
The word "electrophilic" in "electrophilic addition" is derived from the Greek words "elektron" meaning "amber" and "philein" meaning "to love". It was coined by the German chemist Christopher K. Ingold in the early 20th century.
The term "electrophilic" refers to a molecule or atom that has a positive charge or partial positive charge, and thus possesses a strong affinity or "love" for electrons. Electrophiles are electron-deficient species that tend to react with nucleophiles, which are electron-rich species.
The word "addition" refers to the process by which the electrophile adds to a double or triple bond, resulting in the formation of a single bond.
