Types of Reagent:

Electrophilic reagent: All electron deficient atom or group of atoms is known as Electrophilic agent, the electrophile attacks at the electron rich centre.

  1. all positively charged species are electrophile

  1. The compound in which the octet of central atom is not complete

  1. all the compound in which the central atom can expand its octet

  1. all polarizing functional group are electrophilic  as well as nuelophile

 

Nucleophilic reagent: All electron rich compounds are nucleophile and attack at the electron deficient centre.

  1. all negatively charged species

H-, Cl-, NO2-, Br-, CH3- etc.

  1. The compound in which the central atom has lone pair of electron.

  1. all Organ metallic compounds are NucleophileR – Mgx, RLi, R2Cd
  2. The compound having π e- density 

Nucleophilicity:

The power of nucleophile is known as nucleophilicity.
⇒The nucleophilicity of negative charge is greater than the nucleophilicity of lone pair

⇒If lone pair or negative charge is present on the different atom then less electronegativity, more will be the Nucleophilicity.

 CH-3, NH-2, OH-2, F

Nucleophilicity :               CH-3> NH-2> OH-2> F-

⇒NH3 < PH3 < AsH3 < SbH3 < BiH3 (Nucleophilicity)

⇒If negative charge or lone pair of electron is present on the same atom then the less stable negative    charge will be the better nucleophile for example,

Activator & Deactivator:

The groups in benzene which show +M effect or +I effect Increases the electron density on benzene it means they activate the ring towards electrophile and known as activator.

The group which shows –M or –I affect (resultant) decreases the e- density from benzene ring. It means they deactivate the ring towards electrophile
Ortho Para & Meta Director
The groups which shows +I (resultant) or +M effect then negative charge is developed at the Ortho & Para position. Therefore electrophile attack at the Ortho & Para position and the groups are known as OP director.

The groups which shows +I (resultant) or +M effect then negative charge is developed at the Ortho & Para position this means electron density is minimum at the Ortho & Para positions and Electrophile will attack at the meta position the groups are known as meta director.

 
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