The reactivity of a bond or an atom towards a particular reagent in a compound is significantly affected by the availability of electrons. The influence availability of electron density is affected by following factors: inductive effect, mesomeric effect, electromeric effect and hyperconjugation.
In chemical makeup and science, the 'Inductive Effect' is an experimentally observable impact of the transmitting of charge through a chain of atoms in a molecule. It can also define as the process of electron displacement along the chain of carbon atoms.
It is a permanent effect and results due to the presence of a polar covalent bond at one end of the chain and does not depend upon the presence of a reagent. Electrons displaced towards more electronegative atom.
When atom or group of atoms have greater electron attracting capacity than hydrogen this is the electron-withdrawing inductive effect, also known as the -I effect. The positive charge is relayed to the other atoms in the chain, if the electronegative atom joined a chain of carbon atoms. Example of electron-withdrawing inductive effect (-I) effect
• NO2> CN>COOH>F>Cl> Br> I > OH> OCH3 > C6H5 > H
When atoms or group of atoms having smaller electron attracting power than hydrogen, they repel electrons towards carbon atom this is the electron-repelling inductive effect, also known as the +I effect. Example of electron- repelling inductive effect (+I) effect.
• (CH3)3C > (CH3)2CH > CH3CH2 > CH3
The more electronegative atom has a slight negative charge (δ–) and the other atom has a slight positive charge (δ+). In able to decide the point of attack in molecule, inductive affects changes the electron density in a molecule.
The mesomeric effect or resonance effect in chemistry is a property of substituents or functional groups in a chemical compound. Refers to the polarity produced in a molecule as a result of interaction between two pi bonds or a pi bond and lone pair of electrons.
The effect is used in a qualitative way and describes the electron withdrawing or releasing properties of substituents based on relevant resonance structures.
Mesomeric effect is a permanent effect represented by the letter M, It is very prominent in conjugated system and it does not depend on reagent. By changing the electron density in a molecule it can decide the point of attack in molecule.
Mesomeric effect can be positive +M (electron releasing) or it can be negative -M (electron withdrawing or attracting).
+M effect example
–M effect example
In both example oxygen is more electronegative so pi electrons are displaced towards the oxygen atom.
The electromeric effect refers to a molecular polarize ability effect occurring by a multiple bonded compound as it is approached by a reagent.This effect is temporary effect, shown by those compounds containing double or triple bonds.
When a bond is exposed to an attack by a reagent, pi electrons...