Thursday, September 9, 2021

Discovery of free radical by Moses Gomberg

A free radical is an atom or a group of atoms with an odd number of electrons. The odd, unpaired electron in a free radical seeks to pair (form a bond) with another electron. A free radical readily reacts with another atom or group of atoms.

Nineteenth century scientists speculated that there could be a free radical containing carbon — an organic free radical. Ever since the term was introduced by Lavoisier1 in his Traité élémentaire de chimie in 1789 it has not only taken on variant meanings but has been in favour, then out, as new developments in the science convinced chemists that radicals exist, or are preposterous.

But after many attempts to isolate it failed, they concluded they were wrong and that carbon must always be tetravalent (form four bonds).

In 1900, Moses Gomberg, Professor of Chemistry at the University of Michigan, confirmed the existence of a stable, trivalent organic free radical: triphenylmethyl.

In so doing, he challenged the then prevailing belief that carbon could have only four chemical bonds.

In his first paper on the compound Gomberg wrote, "The experimental evidence. . . forces me to the conclusion that we have to deal here with a free radical, triphenylmethyl, (G6H5)3C. On this assumption alone do the results described above become intelligible and receive an adequate explanation".

At the time of his retirement in 1936 he had published 35 experimental papers entitled "On triphenylmethyl" which represented the research which he and his students carried out on the subject. Actually, this figure is low since numerous other papers dealt with ancillary phases of free radical chemistry.

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 confirmed the presence of free radicals in biological materials.

Moses Gomberg was born in Elizabetgrad, Russia, on February 8, 1866, and died in Ann Arbor, Michigan, on February 12, 1947—four days after his eighty-first birthday.

Gomberg’s discovery made a major contribution to theoretical organic chemistry and fostered a field of research that continues to grow and expand.

Moses Gomberg studied analytical chemistry at the University of Michigan and synthetic chemistry in Germany, then the world’s main center of chemical research.
Discovery of free radical by Moses Gomberg

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