The Polar effect or electronic effect in chemistry is the effect exerted by a substituent on modifying electrostatic forces operating on a nearby reaction center. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties In Organic chemistry, a substituent is an atom or group of atoms substituted in place of a Hydrogen atom on the Parent chain of a Hydrocarbon ---- Bold text Coulomb's law', developed in the 1780s by French physicist Charles Augustin de Coulomb, may be stated in scalar form A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called The main contributors to the polar effect are the inductive effect, mesomeric effect and the through-space electronic field effect. The inductive effect in Chemistry is an experimentally observable effect of the transmission of charge through a chain of Atoms in a Molecule The mesomeric effect or resonance effect in Chemistry is a property of Substituents or Functional groups in a Chemical compound.

An electron withdrawing group or EWG draws electrons away from a reaction center. When this center is an electron rich carbanion or an alkoxide anion the presence of the substituent has a stabilizing effect. A carbanion is an Anion in which Carbon has an unshared pair of Electrons and bears a negative charge usually with three substituents for a total of eight An alkoxide is the Conjugate base of an Alcohol and therefore consists of an organic group bonded to a negatively charged Oxygen atom

Examples of electron withdrawing groups are

• halogens (F, Cl);
• nitriles CN;
• carboxylic acids COOH;
• carbonyls CO. Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions A nitrile is any Organic compound which has a - C ≡ N Functional group. Carboxylic acids are Organic acids characterized by the presence of a Carboxyl group, which has the formula -C(=OOH usually written -COOH or -CO2H In Organic chemistry, a carbonyl group is a Functional group composed of a Carbon Atom double-bonded to an Oxygen

An electron releasing group or ERG (otherwise called electron donating groups or EDG) releases electrons into a reaction center and as such stabilizes electron deficient carbocations. A carbocation (ˌkɑrboʊˈkætaɪɒn is an Ion with a positively-charged Carbon Atom.

Examples of electron releasing groups are

• alkyl groups;
• alcohol groups;
• amino groups. An alkyl is a Univalent radical consisting of Carbon and Hydrogen atoms arranged in a chain In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair.

The total substituent effect is the combination of the polar effect and the combined steric effects. See also Intramolecular forces ' Steric effects arise from the fact that each Atom within a Molecule occupies a certain

In electrophilic aromatic substitution and nucleophilic aromatic substitution substituents are divided into activating groups and deactivating groups where the direction of activation or deactivation is also taken into account. Electrophilic aromatic substitution or EAS is an Organic reaction in which an atom usually Hydrogen, appended to an aromatic system is replaced nucleophilic aromatic substitution is a Substitution reaction in Organic chemistry in which the Nucleophile displaces a good Leaving group, In Organic chemistry, a Functional group is called an activating group if a Benzene Molecule to which it is attached more readily participates In Organic chemistry, a deactivating group is a Functional group attached to a Benzene Molecule that removes Electron density from

External links

• Polar effect definition by the IUPAC Gold Book Link