Substituent effects at the origin of a free-radical 1,2-aryl migration and in the related disproportionation reaction of 10-hydro-9-p-X-phenyl-9-phenanthryl radicals

Goerner, Richard N.; Cote, Philip N.; Vittimberga, Bruno M.

doi:10.1021/jo00421a004

Cited by 8 publications

(2 citation statements)

References 9 publications

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“…However, substituent effects at the migratory origin in the neophyl-like rearrangement of (9-/?-X-phenyl-9-fluorenyl)carbinyl radicals (8) have shown that this reaction is also accelerated by electron-withdrawing X substituents (76).…”

mentioning

confidence: 99%

Free-Radical Rearrangements

Beckwith¹,

Ingold²

1980

Organic Chemistry: A Series of Monographs

114

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mentioning

confidence: 99%

Free-Radical Rearrangements

Beckwith¹,

Ingold²

1980

Organic Chemistry: A Series of Monographs

114

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“…To confirm the formation of 4 during the reaction, a model compound 4 was prepared by the reaction between fluorenone and p-methoxyphenyl magnesium bromide, as shown in Scheme 2. 20 The characteristic proton signal of the methoxy protons of 4 (in the presence of TFA) was observed at 3.66 ppm. No peak at 3.66 is observed in Figure 1, which means the reaction of 4 with 2 is very fast compared to that of 1 with 2.…”

Section: Resultsmentioning

confidence: 98%

Synthesis of Hyperbranched Polymer with Degree of Branching of Approximately 100% by Polycondensation of 2-(4-Phenoxyphenoxy)fluorenone

Kono

Sinananwanich

Shibasaki

et al. 2007

Polym J

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ABSTRACT:An approximately 100% branched hyperbranched polymer was successfully prepared using 2-(4-phenoxyphenoxy)fluorenone as a monomer in an acidic medium. The kinetics of the model reaction between 9-fluorenone and anisole was investigated. The reaction obeyed the second-order kinetics, indicating that the first reaction, i.e., the formation of the intermediate from 9-fluorenone and anisole, is considerably slower than the second one, i.e., the reaction of the intermediate with anisole. Based on this finding, a new monomer expected to produce a 100% branched hyperbranched polymer, 2-(4-phenoxyphenoxy)fluorenone, was designed and prepared. Hyperbranched polymers have attracted considerable attention owing to their unique properties such as an intrinsic globular structure, low viscosity, high solubility, and a large number of terminal functional groups. There are many reports on the synthesis and characterization of hyperbranched polymers and their various applications such as those in blended components, photosensitive materials, nonlinear optics, and catalysts. [1][2][3][4][5][6][7][8] Hyperbranched polymers are generally characterized by a degree of branching (DB) that is theoretically approximately 50% for a polymer derived from an AB 2 monomer; this value is assumed on the basis of the equal reactivity of the B functional groups of the AB 2 monomer. 9 The approaches reported to enhance the DB include slow addition, 10 polymerization in the presence of polyfunctional core molecules, 11 use of polyfunctional AB x monomers, 12 and post-synthetic modification. 13 Although these methods improve the DB, they do not result in a 100% DB. To obtain hyperbranched polymers with a 100% DB, the first reaction step of an AB 2 monomer should activate the second reaction.14 Voit et al. have reported the synthesis of a hyperbranched polymer with a 100% DB by the polymerization of an AB 2 -type monomer in ''criss-cross'' cycloaddition with the maleimide group as the A functional group and azine groups as the two B groups. 15 Recently, Smets et al. have reported that the acid-catalyzed polycondensation of isatins or acenaphthenones with aromatic compounds yielded hyperbranched polymers with a 100% DB. 16,17 These reports prompted us to synthesize a hyperbranched polymer with an approximately 100% DB from a common ketone compound.Ordinary ketones such as fluorenone show a poor ability to undergo diarylation; HCl catalyzes the condensation of fluorenone with phenol to afford the corresponding diarylated compound in a 46% yield in 2 d.18 Yamada et al. demonstrated that the diarylation of fluorenone effectively proceeds when 3-mercaptopropionic acid (MPA) is added to the reaction mixture at 65 C. 19Therefore, we expected that the diarylation utilizing an acid with MPA could apply to the synthesis of 100% branched hyperbranched polymer.In this paper, we present the synthesis of a hyperbranched polymer with an approximately 100% DB by the polycondensation of an AB 2 monomer, 2-(4-phenoxyphenoxy)fluorenone. The model reaction of 9...

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Gomberg Free Radical Reaction

2010

Comprehensive Organic Name Reactions and Reagents

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The generation of triphenylmethyl radical is referred to as the Gomberg reaction. It has been found that the triarylmethyl radicals demonstrate different colors while changing temperature, as in quinonoidation. It has been reported that radicals might even be formed during the preparation of Grignard reagents at the initial stage when iodine was used as a catalyst. Up to now, many efficient and convenient methods have been developed to generate free radicals, such as reduction; oxidation; pyrolysis of peroxides, acyl peroxides, and azo compounds; photo irradiation; and trialkylaluminium or trialkylboranes.

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Substituent effects at the origin of a free-radical 1,2-aryl migration and in the related disproportionation reaction of 10-hydro-9-p-X-phenyl-9-phenanthryl radicals

Cited by 8 publications

References 9 publications

Free-Radical Rearrangements

Free-Radical Rearrangements

Synthesis of Hyperbranched Polymer with Degree of Branching of Approximately 100% by Polycondensation of 2-(4-Phenoxyphenoxy)fluorenone

Gomberg Free Radical Reaction

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