Oligomeric radical

Stabilizer molecule Monomer molecule Initiator molecule Primary radical Oligomeric radical... 

Peroxidases are ubiquitous, and many are b-type heme proteins. Several good reviews summarize years of peroxidase research and describe peroxidase applications [57 -61]. Some of the reactions catalyzed by peroxidases are listed in Tab. 10.2 and include oxidation of aromatic and heteroatom compounds, epoxidation, enantioselective reduction of racemic hydroperoxides, free radical oligomerizations and polymerizations of electron-rich aromatics, and the oxidative degradation of lignin [58, 60],... 

The population of no-type particles is increased by the entry of radicals (oligomeric or exited) into n and nj -type particles. They are also formed when monomeric radicals exit an n -type particle (a process that occurs with a rate constant diu)- The population of notype particles is decreased when oligomeric radicals enter an existing particle (to form an nj -type particle), or when an exited radical enters to form an n -type particle. 

Exploration of the template controlled free-radical oligomerization of other activated olefins began with standard monomers utilized in bulk polymer synthesis and the template 63. Vinyl acetate and acrylonitrile led only to uncontrolled polymerization, while vinylene carbonate did not react under the standard experimental conditions. More exotic monomers, such as vinyl trifluoroacetate and rert-butyl acrylate, were also unsuccessful. Only methyl acrylate polymerization was arrested by template 64 to provide the macrocyclized product 96 in modest yield as a mixture of five diastereomers (Scheme 8-25). Subsequent studies with the more effective thiophenyl-bearing template 63 at lower temperatures improved this yield to 35%. The diastereomer distribution was reminiscent of the methyl methacrylate-derived product, although no stereochemical assignments were made in this case either. 

Attempts to extend the template mediated free-radical oligomerization of MMA to the longer (NBD)4-derived template 67 did not afford unequivocal results (Scheme 8-26). 

Saito, J., Kara, J., Toda, S., and Tanaka, S., Analysis of radical oligomerization of styrene by field desorption mass spectrometry, Chem. Lett. (Japan), 1982, 311. 

In general MHRs are obtained by radical oligomerization initiated thermally or with organic peroxides and naphthenates or metal stearates [ 141 ], or by cationic oligomerization initiated with Lewis acids [142]. 

Richards, D. H., Controlled molecular weight in the free radical oligomerization, J. Polym. Sci. Polym. Lett. Ed., 6, 417, 1968. 

The population of type particles is increased by the entry of any radicals (oligomeric or exited ) into n and... 

Oligomeric Vinylphosphonate. A water-soluble oligomer, Fyrol 76 [41222-33-7] is produced by reaction of bis(2-chloroethyl) vinylphosphonate and dimethyl methylphosphonate with elimination of all the chlorine as methyl chloride (127,128). This Hquid, containing 22.5% P, is curable by free-radical initiation, on cotton or other fabrics. Nitrogen components, such as A/-methylolacrylamide or methylolmelamines, are usually included in the finish, which can be durable to multiple launderings (129,130). 

Structure and Mechanism of Formation. Thermal dimerization of unsaturated fatty acids has been explaiaed both by a Diels-Alder mechanism and by a free-radical route involving hydrogen transfer. The Diels-Alder reaction appears to apply to starting materials high ia linoleic acid content satisfactorily, but oleic acid oligomerization seems better rationalized by a free-radical reaction (8—10). 

With more electrophilic halogenated olefins, additions of tnfluoromethyl hypofluonte appear to go by radical processes [139] and give oligomeric products [140] or one-to-one adducts [141,142] (equation 4) depending on reaction conditions... 

Julid investigated the behavior of terfuran 22 and bis(thienyl)furan 23 by cyclic voltammetry as well as the EPR spectra of the radical cations derived from these two compounds. Condensation of the diketone 20 with sulfuric acid furnished furan 22 in 18% yield, while reaction of diketone 21 with hydrochloric acid produced 23 in 84% yield.In a related report, Luo prepared oligomeric bis(thienyl)furans via similar methodology. ... 

The progression of an ideal emulsion polymerization is considered in three different intervals after forming primary radicals and low-molecular weight oligomers within the water phase. In the first stage (Interval I), the polymerization progresses within the micelle structure. The oligomeric radicals react with the individual monomer molecules within the micelles to form short polymer chains with an ion radical on one end. This leads to the formation of a new phase (i.e., polymer latex particles swollen with the monomer) in the polymerization medium. 

In this equation, Mp is the monomer concentration within forming particles, pa is the adsorption rate of oligomeric radicals by the forming particles, Vp is the volume fraction of forming particles within the system, and kp and k, are the rate constants of propagation and termination, respectively. 

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