Beta scission is an important reaction in the
chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
of thermal
cracking of
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...
s and the formation of
free radicals
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron.
With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spon ...
. Free radicals are formed upon splitting the
carbon-carbon bond. Free radicals are extremely reactive and short-lived. When a free radical in a polymer chain undergoes a beta scission, the free radical breaks two carbons away from the charged carbon producing an
olefin
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, a ...
(ethylene) and a primary free radical, which has two fewer carbon atoms.
In organic synthesis, beta scission can be used to direct multistep radical transformations. For example, beta-scission of a weak C-S bond was used to favor one of two equilibrating radicals in metal free conversion of phenols to aromatic esters and acids via C-O transposition.
[Baroudi, A.; Alicea, J.; Flack, P.; Kirincich,J.; Alabugin, I. V. Radical O→C Transposition: a Metal-Free Process forConversion of Phenols into Benzoates and Benzamides, J. Org. Chem. 2011, 76, 1521-37. http://pubs.acs.org/doi/abs/10.1021/jo102467j .(Highlighted in https://www.organic-chemistry.org/Highlights/2011/17October.shtm).]
References
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Reaction mechanisms