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Nucleophiles, also known as “nucleus loving” or “positive–charge loving”, are chemical substances that can provide electron pairs or donate electron pairs to form chemical bonds. We can also say that nucleophiles are Lewis bases. When nucleophiles donate electrons to a proton, it is a Bronsted base. Electrophiles, also known as “electron-loving” or “negative-charge loving”, are chemical substances capable of accepting electron pairs to form chemical bonds. They are Lewis acids. When electrophile accepts electrons at the hydrogen atom of the substance, it is a Bronsted acid. Nucleophilicity and electrophilicity are the capacities up to which the chemical substances can accept or donate electron pairs.
Nucleophiles
- They are chemical substances capable of donating electrons to form chemical bonds
- They have extra electrons, which can be easily donated to a proton or the nucleus that contains the protons. Hence, the name nucleophile has been derived, meaning nucleus-loving
- Ions or molecules with a non-bonded pair of electrons can act as a nucleophile
- A more basic ion is a more reactive nucleophile
- They have extra electrons which they can donate. Hence, they are rich in electrons
- As they have extra electrons, they are attracted to the protons. In other words, they are attracted to the nucleus
- They are negatively charged hence called anions
- They take part in nucleophilic substitution reactions
Electrophiles
- They are chemical substances capable of accepting electrons to form chemical bonds
- They have a deficiency of electrons hence are always ready to accept electrons; hence, they are named electrophiles meaning electron-loving
- Molecules or ions carrying positive charges make great electrophiles
- They are Lewis acids
- They have a deficiency of electrons; hence, they are ready to accept electrons
- They are positively charged hence called cations
- They take part in electrophilic substitution reactions
Differences between Electrophiles and Nucleophiles
Electrophiles | Nucleophiles |
They are also known as Lewis acids as they can accept electrons. | They are also known as Lewis bases as they can donate electrons. |
They are also known as Bronsted acids as they can accept electrons at the hydrogen atom of the particular molecule. | They are also known as Bronsted bases as they can donate electrons to the hydrogen atom of any particular molecule. |
They are generally positively charged, so they are cations. | They are generally negatively charged, so they are anions. |
They have a deficiency of electrons. | They have excess electrons. |
They can undergo various electrophilic reactions like electrophilic substitution reactions, electrophilic addition reactions, etc. | They can undergo various nucleophilic reactions like nucleophilic substitution reactions, nucleophilic addition reactions, etc. |
They can accept electron pairs to form chemical bonds like covalent bonds. | They tend to donate electron pairs to form chemical bonds like covalent bonds. |
All the carbocations are electrophiles | All carbanions are nucleophiles |
They tend to attack the nucleophilic centre of the substrate and carry out electrophilic reactions. | They tend to attack the electrophilic centre of the substrate and carry out nucleophilic reactions. |
Examples: Hydronium ion H3O+, Boron trifluoride BF3, F2, Cl2 Halogen molecules are good electrophiles. | Examples: Halogen anions like I-, Cl-, hydroxide ion OH- and cyanide ion CN- act as good nucleophiles. Alkenes are good nucleophiles. |
Applications of Electrophiles and Nucleophiles
- Electrophiles and nucleophiles are essential in forming covalent bonds between different elements and compounds
- Electrophiles generally form a bond with nucleophiles by accepting electrons
- They help in the reaction mechanisms of various chemical reactions
- They are the backbone of all the chemical reactions in chemistry
- These species take part in addition and substitution reactions
Conclusion
Nucleophiles and electrophiles are chemical substances capable of either accepting or donating electron pairs to form chemical bonds like covalent bonds. Nucleophiles are “nucleus loving” substances that can provide electron pairs or donate electron pairs to form chemical bonds. Nucleophiles, in general, are Lewis bases as they donate electrons. When nucleophiles donate electrons to a proton, it is known as a Bronsted base. Electrophiles or “electron-loving” substances are capable of accepting electron pairs to form chemical bonds. They are Lewis acids as they can accept electrons. When electrophile accepts electrons at the hydrogen atom of the substance, it is known as a Bronsted acid.
