Reasons for chemical reactions in organic chemistry 

• By looking at different functional groups we find that carbon is either bonded with less electronegative atom or more electronegative atom to complete its octet. Due to these electronegativity differences some electronic displacement takes place in the molecule. The effect which creates electronic displacement in organic molecules is called as electronic effect. 

• These effects may be permanent or temporary. • They are of following types 
Inductive effect.
 Resonance or Mesomeric effect.
 Hyperconjugation.
 Electromeric effect.

 

Something for chemical reaction 

• Reactivity of a position in a molecule is determined by the charge density at that position, i.e. an electron deficient species (electrophilic reagent) will attack preferentially at the site of highest electron density and electron rich species (nucleophilic reagent) will attack at the site of lowest electron density.

 • This charge distribution is ascertained by the examination of consequence of electronic factors such as Resonance, Hyperconjugation & Inductive effect. 

• Some reactions proceed via formation of intermediate such as cabocation, carbanion, free radical, carbene, nitrene & benzyne while others do not form intermediate but proceeds through transition state (TS).

 • But one point is common to both i.e. reactivity of different positions in the molecule are determined only by their relative activation energies. Since activation energy depends on the structures of transition state so generally more stable intermediate have lower energy of the transition state & consequently the lower is the activation energy leading to that intermediate formation.

Something for chemical reaction

 • Organic chemistry is very-very simple subject if you have a good command over these tools of organic chemistry which are only few in numbers. So never try to learn the question but try to find the position of electron rich & electron deficient centre in substrate and reagents using the concept of electronic factors and follow my rule i.e. Ajnish rule.

• Golden Rule: During any organic reaction if an intermediate is formed in the rate determining step then stability of intermediate will decide the formation of major product. Greater is the stability of intermediate, major is the corresponding product and the stability of intermediate is generally decided by Resonance, Hyperconjugation & Inductive effect.