Search results
Results from the WOW.Com Content Network
Radical reaction mechanisms use single-headed arrows to depict the movement of single electrons: Example of an arrow-pushing mechanism for an internal radical reaction. The homolytic cleavage of the breaking bond is drawn with a "fish-hook" arrow to distinguish from the usual movement of two electrons depicted by a standard curly arrow. The ...
Free-radical reactions depend on one or more relatively weak bonds in a reagent. Under reaction conditions (typically heat or light), some weak bonds homolyse into radicals, which then induce further decomposition in their compatriots before recombination. Different mechanisms typically apply to reagents without such a weak bond.
A free-radical reaction is any chemical reaction involving free radicals. This reaction type is abundant in organic reactions . Two pioneering studies into free radical reactions have been the discovery of the triphenylmethyl radical by Moses Gomberg (1900) and the lead-mirror experiment [ 1 ] described by Friedrich Paneth in 1927.
This process is known as the radical mediated depolymerization of polystyrene. Radical elimination reactions are found in enzyme-catalyzed pathways. In the dehydrogenation reaction of acyl-CoA to form enoyl-CoA, FAD accepts two protons and two electrons to form FADH2 under the catalysis of acyl-CoA dehydrogenase. [3] The mechanism involves ...
The use of metal hydrides (tin, silicon and mercury hydrides) is common in radical cyclization reactions; the primary limitation of this method is the possibility of reduction of the initially formed radical by H-M. Fragmentation methods avoid this problem by incorporating the chain-transfer reagent into the substrate itself—the active chain ...
Unlike superoxide, which can be detoxified by superoxide dismutase, the hydroxyl radical cannot be eliminated by an enzymatic reaction. Mechanisms for scavenging peroxyl radicals for the protection of cellular structures include endogenous antioxidants such as melatonin and glutathione, and dietary antioxidants such as mannitol and vitamin E. [6]
The reaction mechanism only became clear around 1950, when S. Wawzonek investigated various N-haloamine cyclizations. [11] [12] [13] Noting that the hydrogen peroxide or ultraviolet light greatly improved yields, Wawzonek and Thelan [11] suggested a free-radical mechanism. E. J.
Initiation: The reaction is started by a free-radical source which may be a decomposing radical initiator such as AIBN. In the example in Figure 5, the initiator decomposes to form two fragments (I•) which react with a single monomer molecule to yield a propagating (i.e. growing) polymeric radical of length 1, denoted P 1 •.