Diene scavenging

An interesting approach involving the use of a fluorous dienophile as a diene scavenger under microwave conditions has been investigated by Werner and Curran [101]. The classical Diels-Alder-type cydoaddition of diphenylbutadiene with maleic anhydride as dienophile was accelerated under microwave heating, such that it... 

Scheme 7.88 Diene scavenging utilizing a fluorous dienophile.

In comparison to the cyclization reactions shown above, intermolecular Meerwein arylations are often more difficult to conduct. Since the aryl radical addition to the alkene is no longer favored by the close proximity of the reacting centers, the probability for a direct recombination of the aryl radical with scavengers Y is significantly increased (Scheme 17). To maintain the desired reaction course from 44 to 45 including steps (1) and (2) [89, 90], Meerwein arylations have for a long time mostly been conducted with activated alkenes, such as acrylates (R = COOR ), vinylketones (R = COR ), styrenes (R = Ph), or conjugated dienes [91,92]. These types of alkenes are known for fast addition of aryl radicals. 

Polysaccharides that are mainly found in the gel are also a group of compounds that exhibit antioxidant activities. It was demonstrated that APS-1 (mainly composed b mannose glucose in ratio 18 5) was effective in scavenging superoxide anion radical (dose-dependant fashion), hydroxyl radical, suppressed conjugated diene formation from LDL oxidation induced by Cu, and exhibited a protective effect on hydrogen peroxide-induced injury in PC12 cells 64). Also Kardosova et al. (65) showed that in vitro experiments with acidic and neutral polysaccharides were able to prevent lipid peroxidation by scavenging hydroxyl radicals. 

The mapping shown in Fig. 1 includes references to SBR and styrene block copolymers in the PB search. Removing these citations from the database reduced the number to 4297, which can be seen mapped in Fig. 3. the area of high activity is centered on hydroxy terminated PB (HTPB). Low-Mn HTPB can be prepared by a variety of polymerization processes such as radical, anionic, or even using acyclic diene metathesis (ADMET).f The HTPB has a variety of uses as a propellant. " Other uses include reaction with epoxy resins, nylon, urethane, or even in the formulation of adhesives.t" The use of HTPB as an oxygen scavenger in polyamide, polyvinyl alcohol, and multilayer... 

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