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The hydroxyl radical, Lewis structure shown, contains one unpaired electron. Lewis dot structure of a Hydroxide ion compared to a hydroxyl radical. In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron.
The hydroxyl radical can damage virtually all types of macromolecules: carbohydrates, nucleic acids , lipids (lipid peroxidation) and amino acids (e.g. conversion of Phe to m-Tyrosine and o-Tyrosine). The hydroxyl radical has a very short in vivo half-life of approximately 10 −9 seconds and a high reactivity. [5]
Specific examples include stroke and heart attack. [ citation needed ] In general, the harmful effects of reactive oxygen species on the cell are the damage of DNA or RNA, oxidation of polyunsaturated fatty acids in lipids ( lipid peroxidation ), oxidation of amino acids in proteins, and oxidative deactivation of specific enzymes by oxidation ...
The radical-pair, however, is not simply two radicals. This is because radical-pairs (specifically singlets) are quantum entangled , even as separate molecules. [ 1 ] More fundamental to the radical-pair mechanism, however, is the fact that radical-pair electrons both have spin, short for spin angular momentum , which gives each separate ...
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In the case of chlorination, one of the chlorine atoms replaces a hydrogen atom. The reactions proceed via free-radical pathways, in which the halogen first dissociates into a two neutral radical atoms (homolytic fission). CH 4 + Cl 2 → CH 3 Cl + HCl CH 3 Cl + Cl 2 → CH 2 Cl 2 + HCl. all the way to CCl 4 (carbon tetrachloride) C 2 H 6 + Cl ...
In the third type of substitution reaction, radical substitution, the attacking particle is a radical. [44] This process usually takes the form of a chain reaction, for example in the reaction of alkanes with halogens. In the first step, light or heat disintegrates the halogen-containing molecules producing radicals.