The electrophilicity (Greek philos = friend) is an abstract measure of the ability of an electrophilic ( electron- loving) molecule to react with another molecule, which has an increased electron density in chemistry. The electron-deficient particles is referred to as the electrophile, the reactants as nucleophile. Electrophilic reagents are positively charged or have a strong positive charge. As a result of the reaction, the formation of an atomic bond is observed.

Electrophilic particles

Electrophilic particles or atoms are attracted to negative charges. They themselves are positively charged ( cations), positively polarized (dipole ) or generally have a high desire to receive electrons. Typical electrophiles are carbocations, protons ( H ) and halogens, and carbonyl compounds.

Are Lewis acids. Acids are substances that give off cations or anions or electrons can absorb. Thus, the oxidizing agent, which are reduced in a chemical reaction thereby. There are thus electrophiles, and correspond to electrochemically positive ( anode).

Electrophilic reactions

Electrophilic addition reactions preferably proceed ( Electrophilic addition, AE) on a double bond with the two carbon atoms, or substitution reactions ( electrophilic aromatic substitution, SE) a on an aromatic ring.

Electric phobia

The opposite of electrophilic is elektrophob (Greek phobos = fear). Such a molecule or ion repels electrons, as it has a lone pair of electrons. Electric phobia is usually called nucleophilicity.


There are various methods to organize the extent of electrophilicity in an order of their reactivity, one of them is specified by the ω started by Robert Ghormley Parr electrophilicity index:

With the electronegativity and HSAB concept, Hard and Soft Acids and Bases. This equation is analogous to the classical equation of the relationships for the electric power:

Here is the electrical resistance ( ohms or Ω ) and corresponds to the Voltage.

The electrophilicity index also applies to free radicals. Strongly electrophilic radicals such as the halogens react with electron-rich sites of reaction and strong nucleophilic groups such as 2-hydroxypropyl -2 -yl and tert -butyl radicals react with a preference for electron-deficient reaction sites.