- Synthesis and characterization of eight arylpentazoles
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p-Nitrophenyl-, p-methoxyphenyl-, p-hydroxyphenyl-, p-t-butylphenyl-, p-HOSO2-phenyl-, 15N-p-N,N-dimethylaminophenyl-, 15N2-p-N,N-dimethylaminophenyl-, and dicyanoimidazopentazole were obtained via different synthetic routes. Cesium, barium, potassium, and sodium salts of the arylpentazoles bearing acidic hydrogens were prepared. NMR spectra (1H, 13C) are reported for the arylpentazoles, their corresponding arylazides, and their salts.
- Ek, Stefan,Rehn, Stanley,Wahlstroem, Larisa Yudina,Oestmark, Henric
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p. 261 - 267
(2013/07/05)
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- Star-shaped molecules containing both azo chromophores and carbazole units as a new type of photoresponsive amorphous material
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We synthesized a series of star-shaped molecules containing both azo chromophores and carbazole units (nCz-AZ-X), where n is the number of carbazole units (n = 3 and 6) and X represents cyano (CN) and nitro (NT) as the electron-withdrawing groups on the azobenzenes. The azo compounds existed as amorphous solids at room temperature with glass transition temperatures (T g) of 89, 86, 74 and 73 °C for 3Cz-AZ-CN, 3CZ-AZ-NT, 6Cz-AZ-CN and 6Cz-AZ-NT, respectively. Thin solid films of the azo molecular glasses were obtained by spin-coating. The formation of the photoinduced self-structured surface patterns was investigated by irradiating the solid thin films of the azo molecular glasses with a uniform laser beam (532 nm, 200 mW cm-2) at normal incidence. The formation of surface-relief-gratings (SRGs) was studied by exposing the thin films to an interference pattern of the laser beams (532 nm, 80 mW cm-2). The formation of both the self-structured surface patterns and SRGs showed a close correlation with the electron-withdrawing groups of the azo chromophores and the content of the carbazole units in the molecules. The development of these new star-shaped molecules can add a new member to the category of azo molecular glasses and lead to a deeper understanding of the photoinduced effects and their correlation with molecular structures. The Royal Society of Chemistry 2013.
- Yin, Jianjun,Ye, Gang,Wang, Xiaogong
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p. 3794 - 3801
(2013/07/27)
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- Synthesis and biological evaluation of nitromethylene neonicotinoids based on the enhanced conjugation
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The neonicotinoids with a nitroconjugated system had excellent bioactivity, which could rival imidacloprid, and has been previously reported. However, the photodegradation and hydrolysis of this series of neonicotinoids was very quick according to our further investigation, which cannot be developed as a pesticide further. The approach to further enhance the conjugation was tried not only to increase the bioactivities but also to improve the stability in water and in the sun. A substituted phenyl group was introduced into the furan ring of compound 3. A total of 13 novel neonicotinoid analogues with a higher conjugation system were designed and synthesized. The target molecular structures have been confirmed on the basis of satisfactory analytical and spectral data. All compounds presented significant insecticidal activities on cowpea aphid (Aphis craccivora), cotton aphid (Aphis gossypii), and brown planthopper (Nilaparvata lugens). The stability test exhibited that the stability of novel analogues in water and under the mercury lamp has been improved significantly in comparison to compound 3.
- Lu, Siyuan,Zhuang, Yingying,Wu, Ningbo,Feng, Yue,Cheng, Jiagao,Li, Zhong,Chen, Jie,Yuan, Jing,Xu, Xiaoyong
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p. 10858 - 10863
(2014/01/06)
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- Micellar catalysis in the systems arylamine-diphenylamine-NO 2-
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By methods of UV and IR spectroscopy and thermogravimetry reactions of diazotizaion and azo coupling were studied in the systems of primary arylamine (p-nitro-, p-carboxy- and p-sulfoaniline)- diphenylamine -nitrite ion in water and micellar media on the basis of surfactants. The micellar catalysis effect of sodium dodecylsulfate in the micellar media was revealed. Rate of diazotization was shown to be independent of the surfactants of various types. Formation of ionic associates of azo dyes with dodecylsulfate anions in premicellar region was established and physicochemical characteristics of the associates were estimated.
- Doronin, S. Yu.,Chernova
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scheme or table
p. 2019 - 2024
(2009/04/12)
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- Substituent effects on the thermal cis-to-trans isomerization of 1,3-diphenyltriazenes in aqueous solution
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The thermal cis-to-trans isomerization of some symmetrically p,p′-disubstituted 1,3-diphenyltriazenes has been studied by means of laser-flash photolysis techniques. The geometric isomerization is catalyzed by general acids and general bases as a result of acid/base-promoted 1,3-prototropic rearrangements. Acid catalysis becomes more prominent as the electron-donating character of the para substituent increases, while base catalysis becomes more important as the electron-withdrawing character of the para substituent increases. In addition, the rate ascribed to the interconversion of neutral cis rotamers through hindered rotation around the nitrogen-nitrogen single bond is found to decrease as the electron-withdrawing character of the para substituent increases. Rates of interconversion of neutral cis rotamers are also found to decrease with decreasing solvent polarity, which is indicative of the involvement of a polar transition state. On the other hand, kinetic investigations of the acid-catalyzed decomposition of target triazenes are consistent with an A1 mechanism.
- Chen, Nan,Barra, Monica,Lee, Ivan,Chahal, Navjot
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p. 2271 - 2277
(2007/10/03)
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- Nitration of Anilinium Ions in Concentrated Sulfuric Acid, Catalyzed by Nitrosonium Hydrogen Sulfate
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Successive treatment of aniline first with nitrosonium hydrogen sulfate and then with nitric acid in concentrated sulfuric acid results in nitration of the anilinium ion in the para position, catalyzed by the nitrosonium salt, along with noncatalytic nitration in the meta and para position.No diazotization of aniline followed by nitration of the benzenediazonium cation occurs.
- Gorelik, M. V.,Lomzakova, V. I.,Khamidova, E. A.,Shteiman, V. Ya.,Kuznetsova, M. G.
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p. 371 - 374
(2007/10/03)
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- Mechanism of the Oxidation of NADH by Quinones. Energetics of One-Electron and Hydride Routes
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The kinetics of NADH oxidation by 7 o-benzoquinones and 14 p-benzoquinones were studied by using buffered aqueous solutions and UV/vis spectroscopy.For each quinone the rate law was first order in NADH and first order in quinone.The rate constants varied from 0.0745 to 9220 M-1s-1.Variation of the pH from 6 to 8 gave no change in rate.The use of 4-D and 4,4-D2NADH revealed kinetic isotope effects.The dideutero data gave kH/kD in the range 1.6-3.1 for p-quinones and 4.2 for 3,5-di-tert-butyl-o-quinone.When p-quinones were used, the log k was a linear function of Eo for the quinone/hydroquinone monoanion (Q/QH(1-)) couple with a slope of 16.9 V-1. o-Quinones reacted about 100 times more rapidly, but the same linear relationship with a slope of 16.4 V-1 was observed.Comparisons to data for one-electron-transfer reactions indicate that such mechanisms are not involved.A hydride-transfer mechanism accommodates all the data, and rate-limiting hydrogen atom transfer followed by electron transfer cannot be ruled out.
- Carlson, Brian W.,Miller, Larry L.
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p. 479 - 485
(2007/10/02)
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- COMPARISON OF THE REACTIVITY OF NINE NITROUS ACID SCAVENGERS
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Rate constants have been measured for the reaction of nitrous acid in aqueous solution at 25 deg C with urea, 2,4-dinitroaniline, hydroxylamine, sulphanilic acid, hydrazoic acid, sulfanilamide, hydrazine, sulphamic acid, and 4-nitroaniline, as a function of acidity up to ca. 1.5M.The acid-rate profiles, which are all consistent with mechanisms involving electrophilic nitrosation and various protonation equilibra, give the order of reactivity at each acidity of these potential nitrous acid scavengers.The order of reactivity varies with the acidity because of the different acidity dependences, e.g. the 'best' scavenger at 0.05M acid is 4-nitroaniline followed by sulphamic acid, whilst at 1.3M-acid the most reactive is the hydrazinium ion followed by hydrazoic acid.The effect of added halide ion, thiocyanate ion, and thiourea was also examined.Nitrosation of urea, 2,4-dinitroaniline, hydrazinium ion, and sulphamic acid was not catalysed by any added nucleophile, probably because of the importance, for these substrates containing electron-withdrawing groups, of the reversibility of the initial nitrosation.For the remaining five substrates normal nucleophilic catalysis was observed; analysis of the kinetic date enables the second-order rate constant for attack by the nitrosyl halide, etc. to be evaluated.The recativity sequence NOCl > NOBr > NOSCN > NOSC(NH2)2 was found in each case.
- Fitzpatrick, James,Meyer, Thomas A.,O'Neill, Marion E.,Williams, D. Lyn H.
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p. 927 - 932
(2007/10/02)
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- Reactions of Aryldiazonium Salts and Alkyl Arylazo Ethers. VIII General Acid Catalysis of the Ionization of Alkyl (E)-Arylazo Ethers in Alcoholic Solvents
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Further studies of the general acid-catalysed ionization of alkyl (E)-arylazo ethers in alcoholic solvents have been carried out.The magnitude of catalysis and the degree of proton transfer as a function of the substituent on the aromatic ring, the alkoxide ion nucleofuge, the solvent and the ionic strength have been studied.The results are consistent with a mechanism for the acid-catalysed ionization of alkyl (E)-arylazo ethers in which proton transfer and N-O bond breaking are concerted. 1H and 13C n.m.r. data for a number of alkyl p-nitrophenylazo ethers are reported.
- Broxton, Trevor J.,Stray, Andrew C.
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p. 961 - 972
(2007/10/02)
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