Monday, March 22, 2021

History discovery of free radicals

Free radicals are chemical species which have unpaired electrons on the boundary (atomic or molecular) orbitals.

The term “radical” was first introduced by Guyton de Morveau in 1786 and later used by Gay-Lussac, Liebig, and Berzelius to indicate groups of atoms which were found unchanged in many substances.

For the first time in 1900, Moses Gomberg, Professor of Chemistry at the University of Michigan, speculated the existence of an organic free radical, triphenyl methyl radical (Ph3C•) in the living system.

He published a sensational article entitled ‘Triphenylmethyl, a case of trivalent carbon’, having initiated a new field in organic chemistry, namely, the chemistry of free radicals in solutions.

The scientific community began recognizing the importance of free radicals in 1929, when Friedrich Paneth and Wilhelm Hofeditz produced the methyl free radical, CH3. They prepared the free radical methyl (⋅CH3), by pyrolysis of tetramethyl lead using an adaptation of the system used by Bonhoeffer to study atomic hydrogen.

Later in 1954, Gershman proposed “free radical theory of oxygen toxicity”, according to which, the toxicity of oxygen is due to its ability to form free radicals.

In the same year, the electron paramagnetic resonance (EPR) studies by Commoner in 1954 confirmed the presence of free radicals in biological materials.

In medicine, understanding free radicals, particularly those formed by oxygen, has illuminated the nature of oxidative stress — damage that results when free radicals form faster than the body removes them. This, in turn, has revealed ways human health can be improved — for example, by using antioxidants.
History discovery of free radicals

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