Reagents in Organic Chemistry

Reagents are the chemicals that we add to bring about a specific change to an organic molecule. Any general reaction in organic chemistry can be written as follows:

Substrate + Reagent → Product

Where the substrate is an organic molecule to which we add the reagent. Based on the ability to either donate or abstract electrons, the reagents can be classified as follows:

• Electrophiles
• Nucleophiles

Electrophiles

Electrophiles are electron-deficient organic reagents. It can be generalised that all the positive charge-containing species are electrophiles. For example, H⁺, NO₂⁺, CH₃⁺, Cl⁺ 

Check: Electrophilic Substitution Reaction

Neutral molecules that are electron deficient can also act as electrophiles. Lewis acids like AlCl₃ and BF₃ are examples of neutral electrophiles.

Nucleophiles

Nucleophiles are electron-rich organic reagents. They seek bonding centres with other nuclei and hence the name nucleophile. It can be generalised that negative charge-containing species are nucleophiles. For example, H^–, CH₃^–, and Cl^–.

Neutral molecules with a lone pair of electrons on the heteroatom can act as a nucleophile. For example, H₂O, NH₃, and CH₃OH.