Electrophile

The first question that arises here is “What is an Electrophile”. In simple words, According to the Lewis-Base theory, Electrophile is a Lewis acid as it accepts electrons from an electron-rich species. Electrophile undergoes electrophilic addition and electrophilic substitution reaction. An Addition reaction is simply a reaction in which two or more molecules combine to form a larger one—for example, Halogenation, Hydrogenation, Hydration, Polymerization, Hydrohalogenation. 

Alkyne undergoes an additional reaction to give rise to an alkene or its derivatives. There are three types of Addition reactions: Electrophilic, Nucleophilic and Free-radical. An Electrophilic substitution reaction is a kind of reaction in which an Electrophile replaces the functional group attached to a compound. The functional group is generally a hydrogen atom. An electrophile is an electron seeking reagent that takes away a pair of electrons from a Lewis Base(which donates electrons). An electrophile is classified into two main categories: Positive Electrophile, and the second one is named Neutral Electrophile.

Electrophiles move from a high-density area to a low-density area. An Electrophile always attacks the substrate species with a higher electron density. An electrophile is composed of two different words: Electro and Phile. Here, Electro means Electron(negatively charged particles), and Phile means Loving. This shows that an Electrophile is an electron loving species. In some exceptional cases, all the positive species do not act as Electrophile; species such as NH4+, Na+, Ca2+ do not act as Electrophile because their Octet is complete. The movement of electrons is fully dependent upon the density. It accepts a pair of electrons from a Covalent Bond. All the Carbocation compounds come under the category of Electrophile. Electrophiles generally contain two electrons less than an Octet, due to which their Octet remains incomplete, and thus they seek an electron-rich molecule to complete its Octet. E+ represents these.

Types of Electrophiles

There are usually two kinds of Electrophiles:

Positive Electrophile: Electrophile that contains a positive charge is known as Positive Electrophile. Example CH3+

Neutral Electrophile: Electrophile that neither contains positive nor negative charge is known as Neutral Electrophile. Example: AlCl3, BF3, Acid chlorides etc. 

Electrophiles are derived from Xenobiotics. They can react with the Biological Nucleophiles on macrophages and can modify them covalently and thus can cause toxicity. Cellular toxicity can occur if they react to proteins, while reactions with nucleic acid can cause gene mutations and carcinogens.

What is a soft Electrophile?

A molecule that accepts a proton during a primary reaction step is Soft Electrophile. Soft Electrophiles are less polarised than Strong Electrophiles. Most electrophiles are positively charged. They either contain an atom with a partial positive charge or an atom that does not contain an Octet of electrons. Electrophiles usually interact with nucleophiles through addition and substitution reactions. Some Electrophile atoms may also contain lone pairs. A good Electrophile contains weak polar bonds. Electrophiles are always ready to accept electrons from other molecules. Now we will have a look at the Importance of electrophiles.

 In Organic chemistry, Electrophiles play a very important role in a chemical reaction between different atoms or chemical species. Electrophile helps in forming many chemical reactions and new compounds when they get attracted to Nucleophiles. As proved that positive and negative always attract, this is the reason for the attraction between Electrophiles and Nucleophiles, which are positive and negative charge carriers respectively. 

All that we studied in this article is about Electrophile, what it means, types of Electrophile charges present on an Electrophile, and the role of Electrophile, i.e., its Importance in Organic chemistry. So, to revise the complete topic, let us have a summarization.

In the starting, we talked about Electrophile; an Electrophile is an electron-deficient molecule that seeks an electron-rich atom or molecule to accept a pair of electrons from that molecule in a chemical reaction. An Electrophile is composed of two words, Electro and Phile, where Electro means Electron and Phile means loving. Because an Electrophile takes over the electrons, it is also called an Electron loving species. An Electrophile is a Lewis acid, which reacts with a Nucleophile that is a Lewis base. Lewis acid is a molecule that accepts a pair of electrons, while Lewis base is such a kind of molecule that donates a pair of electrons. Electrophile usually accepts electrons to complete their Octet.

Electrophiles are usually of two main types: Positive Electrophile and Neutral Electrophile. Positive are the ones carrying a positive charge, and Neutral are the ones that neither contain positive charge nor negative. All the carbocations come under the category of Electrophiles. Due to some exceptions, NH4+,Na+,Ca2+ are not considered as Electrophiles. The reason behind this is that they already have a complete Octet.

Conclusion

Electrophiles play a very important role in Organic chemistry; it helps form new chemical reactions and new molecules when it interacts with their opposite charged molecule, i.e., Nucleophile. Some examples of Electrophiles are hydronium ion (H3O+, from Bronsted acids), boron trifluoride (BF3), aluminium chloride (AlCl3), and halogen molecules fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2).