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In chemistry, a radical, also known as a free radical, is an atom, molecule, ... Stability is conferred to the radical anion when the charge can be delocalized.
The free radical theory of aging states that organisms age because cells accumulate free radical damage over time. [1] A free radical is any atom or molecule that has a single unpaired electron in an outer shell. [2] While a few free radicals such as melanin are not chemically reactive, most biologically relevant free radicals are highly ...
The substituents can kinetically stabilize radical centers by preventing molecules and other radical centers from reacting with the center. [3] The substituents thermodynamically stabilize the center by delocalizing the radical ion via resonance. [1] [3] These stabilization mechanisms lead to an enhanced rate for free-radical reactions. [5]
In organic chemistry, free-radical halogenation is a type of halogenation. This chemical reaction is typical of alkanes and alkyl-substituted aromatics under application of UV light. The reaction is used for the industrial synthesis of chloroform (CHCl 3), dichloromethane (CH 2 Cl 2), and hexachlorobutadiene. It proceeds by a free-radical chain ...
In free radical polymerization, radicals formed from the decomposition of an initiator molecule are surrounded by a cage consisting of solvent and/or monomer molecules. [6] Within the cage, the free radicals undergo many collisions leading to their recombination or mutual deactivation. [5] [6] [9] This can be described by the following reaction:
The double bonds of an unsaturated fatty acid can be cleaved by free-radical reactions involving molecular oxygen. This reaction causes the release of malodorous and highly volatile aldehydes and ketones. Because of the nature of free-radical reactions, the reaction is catalyzed by sunlight. [7] Oxidation primarily occurs with unsaturated fats.
The ability of hindered amine light stabilizers (HALS or HAS) to scavenge radicals produced by weathering, may be explained by the formation of aminoxyl radicals through a process known as the Denisov Cycle. The aminoxyl radical (N-O•) combines with free radicals in polymers: N-O• + R• → N-O-R
The mitochondrial theory of ageing has two varieties: free radical and non-free radical. The first is one of the variants of the free radical theory of ageing. It was formulated by J. Miquel and colleagues in 1980 [1] and was developed in the works of Linnane and coworkers (1989). [2] The second was proposed by A. N. Lobachev in 1978. [3]