Difference Between Electrophile and Nucleophile

Introduction

Christopher Kelk Ingold 1933 introduced the terms nucleophile and electrophile by replacing the words anionic and cationic words introduced by A. J. Lapworth. The word electrophile is obtained by the combination of two words 'electro' meaning electrons and 'philes' meaning loving. And the word nucleophile is obtained from the two words nucleus and phile, which is a Greek word 'Philos' meaning a friend. These two terms are important in chemistry. These chemical compounds participate in many organic reactions. As we know electrophiles and nucleophiles have opposite behaviour which is the driving force for several chemical reactions. So these terms are very important for a better understanding of chemical reactions.

Overview of Nucleophiles

Nucleophiles are chemical species that can donate a pair of electrons present on them. So all the nuclear files contain lone pair of electrons in them. They are electron-rich species which is the reason why they donate electrons. The term nucleophiles can also be split into two 'Nucleo' and 'philes', which means nucleus-loving species. As they can donate the pair of electrons present on them it is called a Lewis base. They are neutral species with lone pair of electrons or negatively charged species. These chemical species, therefore, donate the pair of electrons in a chemical reaction and which further leads to the formation of covalent bonds. The extent to which particular nucleophiles can donate the pair of electrons is given by the term nucleophilicity and is similar to the word basicity. Ammonia is an example of a nucleophile as it contains lone pair of electrons.

Examples of Nucleophiles

As nucleophiles are negatively charged or they are species that contain lone pair of electrons. Some examples of nucleophiles can be given as,

• All the halogen anions, $\mathrm{Br^{-}\:,\:Cl^{-}\:,\:I^{-}}$

• Cyanide,$\mathrm{CN^{-}}$

• Hydroxide ion, $\mathrm{OH^{-}}$

• Water, $\mathrm{H_{2}O}$

• Ammonia, $\mathrm{NH_{3}}$

• Sulfuric acid, $\mathrm{H_{2}SO_{4}}$

Features of Nucleophiles

Some of the important features that nucleophiles must process are discussed in detail below.

• Charge − A nucleophile must be negatively charged or it must contain a lone pair of electrons even if it is a neutral species. So nucleophiles are commonly negatively charged species. And the nucleophilicity of nucleophiles increases with the increase of the negative charge.

• Electronegativity − As nuclear files can donate the electron pairs present on the electronegativity of nucleophiles must be lower innovative act as a better nucleophile. So nuclear files are generally less electronegative species.

• Solvent effect − If the solvent present on the nucleophiles during a particular chemical reaction is polar or protic It will ultimately affect the strength of nucleophiles. Thus polar solvents may form hydrogen bonds with the lone pair of electrons present in nucleophiles thereby reducing the chances of The lone pair donating the electron present on them to someone else.

• Steric hindrance − Nucleophiles must not be sterically hindered as it may affect the rate of nucleophilic reactions. So a good nucleophile is sterically less hindered.

Overview of Electrophiles

Electrophiles are chemical compounds that are electron deficient. So they are electronic efficient so they can accept electrons towards it. The word electrophiles can be split into two words that are 'electro' and 'philes'. Together the word electrophiles means electron-loving species. These chemical compounds may be positively charged or neutral species. These compounds will participate in electrophilic substitution and electrophilic addition reactions. Electrophiles are also called Lewis acids since they like electron pairs. So these chemical species accept a pair of electrons during a chemical reaction and then lead to the formation of a covalent bond. The extent to which an electro file can accept electrons is given by the term electrophilicity and is similar to the word basicity. 𝐻3𝑂+is an example of electrophile.

Examples of Electrophiles

Some examples of electrophiles that are positively charged or electron-loving species are discussed below.

• Boron trifluoride, $\mathrm{BF^{3}}$.

• Hydronium ion, $\mathrm{H^{3}O}$.

• Aluminium trichloride, $\mathrm{AlCl^{3}}$.

• Halogen molecules such as $\mathrm{Cl^{2}\:,\:Br^{2}\:,\:F^{2}\:and\:I^{2}}$.

Features of Electrophiles

Some of the important features that are needed to be an electrophile a good electrophile are discussed in detail below.

• Charge − An electrophile must be positively charged or it may contain a vacant orbital to accommodate electrons during a reaction from nucleophiles.

• Bond type − The bond present in an electrophile must be weak only then it can accept electrons towards it so the bond of the electrophile must be weak polar bonds.

• Steric hindrance − The electrophiles must not be crowded only then electrons can be donated to it by nucleophiles.

Difference Between Electrophiles and Nucleophiles

Some of the differences between electrophiles and nucleophiles are tabulated in the following table.

Electrophile	Nucleophiles
They are generally positively charged chemical species.	They are generally negatively charged chemical species.
They accept electrons towards it.	They donate electrons.
It must contain one vacant orbital.	It contains a lone pair of electrons.
Generally represented by 𝐸+.	Generally represented by 𝑁𝑢−.
Electron deficient species.	Electron-rich species.
They are Lewis acids.	They are Lewis bases.
Participate in electrophilic substitution and addition reaction.	Participate in nucleophilic addition and substitution reactions.
$\mathrm{BF_{3},AlCl_{2}}$ ,etc. are examples	$\mathrm{I^{-},Cl^{-},CN^{-}}$ , etc. are examples.

Conclusion

Chemical reactions take place by the donation and acceptance of electrons from one species to another species. Electrophiles and nucleophiles are two important chemical species that are necessary to undergo a chemical reaction. Electrophiles are the species that are positively charged or a container back in the orbital to acceptive electrons. While nucleophiles are the chemical species that negatively charge lone pairs of electrons so that they can donate this pair of electrons to another species. Some of the examples of electrophiles are $\mathrm{BF_{3},AlCl_{3}}$, etc. And examples of nucleophiles are 𝐶𝑁−, 𝑂𝐻−, etc. The important features of electrophiles and nucleophiles are affected by factors such as charge, electronegativity, steric hindrance, etc.

FAQs

1. Why 𝑭− not a nucleophile?

The nucleophilicity of nucleophiles depends on the electronegativity of atoms. Electronegativity is the ability of an atom to accept the pair of electrons towards it. So more electronegative atoms will not donate the pair of electrons present in them. Since Fluorine is the most electronegative atom, F- is not a good nucleophile.

2. Is 𝑪𝑯− a nucleophile?

𝐶𝐻− is a good nucleophile as the carbon atom is a small atom, and the ability of this element to hold the negative charge is low. So 𝐶𝐻− is even more nucleophilic than 𝑁𝐻−

3. Is $\mathrm{CCl_{4}}$ an electrophile?

$\mathrm{CCl_{4}}$ is an electrophile since the chlorine atom present in the Carbon tetrachloride contains a vacant d orbital so it can act as an electrophile.

4. Is $\mathrm{PH_{3}}$ a nucleophile or an electrophile?

$\mathrm{PH_{3}}$,Phosphine is a nucleophile since it contains one lone pair of electrons. They can donate the pair of electrons present on them. But when they dissolve in water they also accept the pair of electrons present in the water molecule. And the process is hydrolysis and results in the formation of phosphorus acid.

5. What is the effect of the electron-withdrawing group on the electrophiles?

The presence of electron-withdrawing in particular electrophiles makes electrophiles more electrophilic. This is because the attachment of the electron-withdrawing group will take the electrons already present in those electrophiles. And this will further make them more electrophilic. So the effect of the electron-withdrawing group is that it will increase the electrophilicity of compounds.