Homolytic and Heterolytic fission

Chemical reactions occur when a chemical link is broken or rearranged. A chemical reaction is dependent on the sort of chemical connection that is broken. The term “bond fission” refers to the dissolution of a chemical link (typically a covalent bond). Homolytic and heterolytic fission are two main types of bond fission.

Homolytic fission

Homolytic fission, also known as hemolysis, is a kind of bond fission that entails the dissociation of a certain molecule in which each of the original pieces maintains one electron. As a result of homolytic fission, two free radicals are produced. This process occurs when a neutrally charged molecule undergoes homolytic fission, resulting in two free radicals, each of which contains one electron obtained from the bond pair.

A homolytic fission is also called a homolytic cleavage or a bond homolysis, depending on the context. These expressions are derived from the Greek word ‘homo,’ which translates approximately as ‘equal breaking.’

In some cases, homolytic fission can be induced by applying a little amount of heat to the molecule. One such example is the homolytic breakdown of oxygen-oxygen bonds in peroxides. These intramolecular bonds are rather weak, with very low bond dissociation energies. As a result, just a negligible amount of heat energy is necessary to break through this barrier.

Heterolytic fission

It is also known as heterolysis. Heterolytic fission is a type of bond fission in which a covalent link between two chemical species is broken unevenly, with one of the chemical species containing a bond pair of electrons and the other chemical species containing no electrons capable of escaping the bond pair, as opposed to homolytic fission. The primary products of heterolytic fission are neutrally charged molecules carrying cations, or positive charges, and those possessing negative charges, referred to as anions.

The chemical species that are unable to retain any of the bound electrons following the bond fission are referred to as cations. These cations are essentially positively charged ions that are the product of any neutral molecule’s heterolytic fission. On the other hand, the negatively charged heterolysis product, also called anions, is described as a chemical entity that maintains both bonded electrons via the bond fission process.

The heterolytic bond dissociation energy is the energy required to dissociate a covalent bond by heterolytic cleavage (not to be confused with homolytic bond dissociation energy). This image is occasionally used to depict the bond energy of a covalent bond. One of the most common examples of heterolytic fission is the fission of a hydrogen chloride molecule, which results in the formation of hydrogen ion as a cation and chloride ion as an anion, as seen below.

What exactly is the difference between homolytic fission and heterolytic fission?

Homolytic fission is the process by which a chemical bond is broken and two equal pieces are formed. Each fragment receives one electron from the bond. The energy absorbed or released during homolytic fission is referred to as the “homolytic bond dissociation energy.” Heterolytic fission is the process by which a chemical bond is broken and two unequal pieces are formed. It gives one fragment with two bond electrons and the other with none. The major distinction between homolytic and heterolytic fission is that the former produces more neutrons than the latter. The energy absorbed or released during heterolytic fission is referred to as the “heterolytic bond dissociation energy.”

Homolytic and heterolytic fission examples

The homolytic breakage of an A-B bond results in the production of free radicals A° and B°. Fission or heterolysis. Heterolytic bond cleavage occurs when a covalent bond undergoes fission in such a way that both bonding electrons are removed by one of the bound atoms.

Conclusion

Fission is the breakup of bonds. There are two types of fission: homolytic and heterolytic. The distinction between homolytic and heterolytic fission is that homolytic fission provides each fragment one bond electron, but heterolytic fission offers one fragment two bond electrons and the other fragment none.