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1.
The photooxidation and its electron transfer (ET) mechanism of acenaphthenone (ANO) sensitized by 9,10-dicyanoanthracence (DCA) are investigated. It has been found that the reaction with a stepwise manner led to the formation of 1,8- (3'-hydroxy)-β-naphthalene lactone and 1,8-naphthalenedicarboxylic anhydride. By cyclic voltammetry, fluorescence quenching, exciplex emission, co-sensitbation of biphenyl/DCA as well as CIDNP studies, it is verified that ANO can behave as an electron donor to undergo ET reaction with singlet DCA which is a thermodynamically-favored process. 相似文献
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DCA-sensitized electron-transfer photooxygenation of tetraphenylallene () in acetonitrile yields benzophenone () and polymeric material. In acetone, the yield of is better than twice the amount obtained in acetonitrile and very little of polymeric material is observed. If the acetone solution is worked-up immediately after the oxygen consumption ceased, 1,3-dihydroperoxy-1,1,3,3-tetrapheny]-2-propanone () is isolated. Its formation is proposed to occur via the peroxyallyl zwitterion and the tetraphenylcyclopropanone () (Scheme 1). decomposes slowly into , and CO + CO2 (3:1) in neutral solution; in the presence of a base, decomposition is fast, resulting in the formation of two molecules of , one molecule of water, and one molecule of CO2 . Decomposition of in the presence of various fluorescers and a base yields a bright fluorescence of the additives. 相似文献
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Nobuo Nakabayashi Harold G. Cassidy 《Journal of polymer science. Part A, Polymer chemistry》1969,7(5):1275-1278
By condensing a hydroquinone bis-lactone of 1,4-dihydroxybenzene-2,5-bis(ethyl-2′-carboxylic acid) with diamines such as hexamethylene diamine, piperazine, 4-aminoethylpiperidine, or 1,3-di-(4′-piperidinyl) propane, redox polyamides can be prepared. The lactone functions protect the hydroxyl groups until the polymerization occurs at which point, due to the opening of the lactone rings, free hydroquinone hydroxyls appear. The resulting polymer is oxidizable. When the oxidized polymer is reduced the viscosity is higher than that of the original reduced polymer. 相似文献
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Keikichi Uno Mutsuko Ohara Harold G. Cassidy 《Journal of polymer science. Part A, Polymer chemistry》1968,6(10):2729-2740
Ten vinylhydroquinone and one vinyl resorcinol derivatives are compared, particularly with respect to NMR spectra and copolymerizability with styrene. They are vinylhydroquinone dimethyl ether (I), vinyl-O,O′-bis(1-ethoxyethyl)hydroquinone (II), vinylhydroquinone di(2-pentyl)ether (III), 4-vinyl resorcinol bismethoxymethyl ether (IV), 2-vinyl-5-methylhydroquinone dimethyl ether (V), 2-vinyl-5-methyl-O,O′-bis(1-ethoxyethyl)hydroquinone (VI), 2-vinyl-6-methylhydroquinone dimethyl ether (VII), 2-vinyl-5-tert-butylhydroquinone dimethyl ether (VIII), 2-vinyl-5-chlorohydroquinone dimethyl ether (IX), 2-vinyl-3,6-dimethylhydroquinone dimethyl ether (X), and 2-vinyl-3,5,6-trimethylhydroquinone dimethyl ether (XI). All the vinyl protons have almost the same coupling constants. Though subtle distinctions are found among all the spectra, they can in general be put into two groups on the basis of the chemical shifts. Let the hydrogen on carbon-1 of the vinyl group be A, the hydrogen cis to A be B the hydrogen trans to A be C, then in the first group, (I) through (IX), the chemical shifts (τ) are (A) 3.02 ± 0.08, (C) 4.41 ± 0.05, and (B) 4.87 ± 0.07, and in the second group, (X) and (XI), they are (A) 3.30 ± 0.03, (C) 4.49 ± 0.01, and (B) 4.59 ± 0.03. It is supposed that in (X) and (XI) the vinyl group is out of the plane of the ring, because of the two ortho substituents, and this conformation is reflected in the NMR data. Ultraviolet spectra are consonant with this interpretation, since the λmax of (X) and (XI) correspond closely with those of nonvinyl reference compounds, while those of (II), (V), and (VIII) are shifted to longer wavelengths. When these compounds are copolymerized separately with styrene, the behaviors are classifiable into the following three groups, where r1 and r2 are monomer reactivity ratios with styrene as the first monomer: (i) r1 < 1 and r2 < 1 for compounds (II) and (III) and the reference compound O,O′-dibenzoylvinylhydroquinone, (ii) r1 < 1 and r2 > 1 for compounds (I), (V), (VII), (VIII), (IX), and (iii) r1 > 1 and r2 = 0 for compounds (X) and (XI). These behaviors are correlated with the effect of electronegativity of groups on the stability of the radical at the growing end of the chain and with the simultaneous effects of steric hindrance. 相似文献
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Studies on the photooxidation mechanism of polymers. I. Photolysis and photooxidation of polystyrene
A new mechanism has been proposed for the photooxidation of polystyrene as film and in benzene. The initial stage of the photooxidative degradation may involve reactions of singlet oxygen with polystyrene molecules. Singlet oxygen may be formed in the reaction between excited benzene ring in polystyrene molecule and molecular oxygen. The addition of singlet oxygen quenchers such as 1,3-cyclohexadiene or β-carotene reduces the rate of polymer degradation in benzene solution. The mechanisms of the photolysis of polystyrene as film and in benzene solution, in vacuo and in the presence of oxygen, are discussed and interpretations proposed. The pronounced yellowing of polystyrene during the photooxidation process is interpreted as a reaction involving benzene ring-opening photooxidation in polystyrene molecule. These results were obtained by comparing ultraviolet and infrared spectra in experiments of photooxidation of pure liquid benzene and polystyrene film. 相似文献
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Kazuhiko Mizuno Nobuyuki Ichinose Toshiyuki Tamai Yoshio Otsuji 《Tetrahedron letters》1985,26(47):5823-5826
The 9,10-dicyanoanthracene-sensitized photooxygenation of biphenyl and its derivatives in the presence of Mg(ClO4)2 in acetonitrile brought about the oxidative cleavage of benzene nucleus to give benzoic acid and its derivatives. 相似文献
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Tatsuya Kanno Takahide Oguchi Hirochika Sakuragi Katsumi Tokumaru 《Tetrahedron letters》1980,21(5):467-470
Irradiation of semiconductors (TiO2 and CdS) suspended in organic solvents containing 1,1-diphenylethylene and its derivatives under oxygen afforded the corresponding epoxides and benzophenone. A possible mechanism is discussed. 相似文献
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[reaction: see text]. The riboflavin-catalyzed photooxidation of 2',3',5'-tri-O-acetyl-8-oxo-7,8-dihydroguanosine generates a radical intermediate that is competitively trapped by H(2)O, O2(-)(*), or O(2). The products of H(2)O trapping have been previously described as the spiroiminodihydantoin (pH >or= 7) and iminoallantoin/guanidinohydantoin (pH < 7) nucleosides. Trapping by O2(-)(*) leads to the oxaluric acid (pH or= 8.6) pathways (R' ', R' ' = H or 2,3,5-tri-O-Ac-ribofuranosyl). The pH-dependent role of superoxide was probed using Mn-SOD and compared to guanosine and 8-methoxyguanosine photooxidation. 相似文献
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Nobuo Nakabayashi Gerhard Wegner Harold G. Cassidy 《Journal of polymer science. Part A, Polymer chemistry》1969,7(5):1269-1274
Redox polyurethanes, polyesters, and alternate copolyurethanes and copolycarbonates from two kinds of benzoquinonyl glycol were prepared based on 2-(duroquinonyl)-propan-1,3-diol. The oxidized polymer is stable. When the fully reduced polymer in solution is exposed to air the durohydroquinonyl residues are oxidized to the quinone form while the less substituted hydroquinonyl glycol residues remain stable in the reduced form. There is thus prepared polymer with oxidized and reduced groups alternating along the chain. 相似文献
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Tris(p-bromophenyl ammoniumyl) tetrafluoroborate induces an easy electron-transfer process on dioxenes leading quantitatively to the corresponding α-diketones. A mechanism involving the disproportionation of the intermediate radical cations is discussed. 相似文献
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N. A. Weir 《Journal of polymer science. Part A, Polymer chemistry》1978,16(5):1123-1136
Dielectric loss measurements have been applied to study the short-wave (λ = 254 nm) and long-wave (λ > 300 nm) photooxidation of polystyrene which had been prepared using both free radical and anionic initiator. The high-frequency loss peak, attributable to carbonyl products of oxidation is a sensitive monitor of the rate of oxidation, the sensitivity being greater than that of manometric measurements. The data are specific to carbonyl compounds and the technique is particularly suitable for studying the surfaces, on which most of the above photooxidation occurs with polystyrene. Effects of radiation intensity and oxygen pressure were also studied. The measurements have permitted a more detailed study of the long-wave photooxidation process than has previously been undertaken, and the results emphasize differential reactivities of radically and anionically prepared polymers. Results are interpreted in terms of initiation by both impurities and charge-transfer complexes. 相似文献
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Anna Painelli Francesca Terenziani Zoltán G. Soos 《Theoretical chemistry accounts》2007,117(5-6):915-931
We discuss electron-transfer processes that govern the physics of several materials or systems of interest for advanced applications.
The discussion touches upon several topics, ranging from solvatochromism to solvent-induced symmetry breaking, from excitonic
to cooperative effects in molecular crystals, from phase transitions to vibrational contributions to the dielectric constant
in organic materials, from spectroscopy to molecular transport. In all these diverse systems electron transfer (ET) plays
a major role and is discussed with reference to simple models for delocalized charges. 相似文献
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