- Spectroscopic and thermal properties of newly mixed azocalix[4]arene ester derivatives
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The mono-, di-, tri-, and tetra-acryloyl esters of p-chloroazocalix[4]arene which include the first examples of mixed azo ester dyes were synthesized by reacting acryloyl chloride with sodium salts of p-chloroazocalix[4]arene in tetrahydrofuran with inert atmosphere. Diazonium salt of p-chloroaniline was synthesized by using n-amlynitrite and coupled with calix[4]arene in anhydrous condition. This is the diazo coupling reactions used for the first time for synthesized azocalix[4]arene. The characterization of synthesized compounds by spectroscopic methods revealed that azocalix[4]arenes adopt a cone conformation if they contain at least one free phenolic group. The structures of these compounds have been characterized by infrared (IR), ultraviolet-visible (UV-VIS), proton nuclear magnetic resonance (1H NMR) and carbon nuclear magnetic resonance (13C NMR). Differential thermal analysis (DTA), thermogravimetry (TG) and derivative thermogravimetry (DTG) were used to determine the thermal behaviors of the compounds.
- ?zkinali, Sevil
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- Photocatalytic degradation of imidacloprid by phosphotungstic acid supported on a mesoporous sieve MCM-41
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Solid catalysts consisting of polyoxometalates (POM) namely phosphotungstic acid H3PW12O40 (HPW) supported on a mesoporous sieve MCM-41 have been prepared and characterized by FT-IR, X-ray diffraction, nitrogen adsorption and high resolution transmission electron microscope (HRTEM). The HPW/MCM-41 with different HPW loadings from 10 to 60 wt% possess large specific surface area and rather uniform mesopores. Keggin structure of HPW retains on the prepared composite catalysts. The photocatalytic performance of HPW/MCM-41 was examined by degradation of a durable pesticide imidacloprid. It is found that the prepared photocatalysts exhibit high activity under irradiation of 365 nm monochromatic light. For 50 mL of imidacloprid (10 mg/L), conversion of imidacloprid using 20 mg of HPW/MCM-41 with 50 wt% loading level and calcined at 300°C reaches 58.0% after 5 h irradiation. Copyright
- Feng, Changgen,Li, Yanzhou,Liu, Xia
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experimental part
p. 127 - 132
(2012/03/09)
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- Formation of Organic Nitro-compounds in Flowing H2O2+NO2+N2+Organic Vapour Systems. Part 3.-Effects of O2 Addition on H2O2+NO2+N2+Alkane Systems
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The effects of oxygen on the product distribution from the surface-initiated reactions in flowing mixtures of H2O2, NO2, N2 and RH, where RH=ethane, propane, n-butane and n-pentane, at 298 K have been studied.In the absence of O2, the principal products are the corresponding nitroalkane, alkyl nitrite and alkyl nitrate.In the presence of sufficiently large concentrations of O2, the predominant product is the alkyl nitrate and the only other products of significance, in some cases, are the corresponding carbonyl compounds.The variation of the product yields with / gives values for the rate-constant ratios k8/(k3+k4) for reaction at both primary and secondary radical sites:.Possible mechanisms by which the products are formed are discussed.
- Baulch, Donald L.,Campbell, Ian M.,Chappel, Jonathan M.
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p. 617 - 628
(2007/10/02)
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- Formation of Organic Nitro-compounds in Flowing H2O2+NO2+N2+Organic Vapour Systems. Part 2.-H2O2+NO2+N2+Alkane System
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The principal products from the surface-initiated reactions in flowing mixtures of H2O2, NO2,N2 and RH, where RH=ethane, propane, n-butane and n-pentane, have been identified as the nitroalkane, alkyl nitrite and alkyl nitrate.The product yields have been measured; in the case of propane the variation of the yields with total gas pressure has also been studied.Values have been obtained for the relative rates of primary and secondary H-atom abstraction from each alkane by OH and for the rate-constant ratios k3/k4 and k5/k6 at 298 K:.The trends in the product yields with the variation of pressure and change of R indicate that RO radicals are produced via reactions (4)-(6) rather than by a single-step reaction of R with NO2.
- Baulch, Donald L.,Campbell, Ian M.,Chappel, Jonathan M.
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p. 609 - 616
(2007/10/02)
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- Chemistry of peroxyacyl nitrates. Part III. The oxidation of thioethers by peroxyhexanoyl nitrate
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The reaction of peroxyhexanoyl nitrate, 1a, a homologue of the atmospheric pollutant "PAN", 1b, with some twenty thioethers, is described.At 0-25 deg C, common thioethers such as Et2S or PhSMe are rapidly converted into sulfoxides in high yields in a variety of solvents, ranging from pentane and chloroform to acetic acid, methanol and aqueous acetonitrile.Rates are essentially solvent-independent, although the reaction is subject to marked steric hindrance.Relative rates for five p-substituted thioanisoles in MeOH at 22 deg C, leading to a Hammett ρ-value of -1.7, show that the sulfur atoms display nucleophilic character.Electron-attracting groups on α-carbon, such as in PhSCCl3 and in MeSCH2OC(O)Ph, inhibit the formation of sulfoxide.Addition of EtSH lowers the yield of sulfoxide, producing instead EtSSEt and EtSNO.Oxidation of Me2S by 1a with the NO2 group labelled by 18O does not give rise to 18O-enriched DMSO.Comparison of (CH3)2S with (CD3)2S revealed an inverse kinetic H/D isotope effect.The products obtained from 1a vary with solvent.In the presence of water or EtSH, hexanoic acid is formed, while methanol gives rise to methyl hexanoate, and in pentane/hexanoic acid, hexanoic anhydride is produced.In aprotic solvents, significant amounts of CO2 are formed.These observations can best be rationalized on the basis of an intermediate sulfurane R1R2S(ONO2)(OCOR), (I), produced from thioether R1SR2 and 1a, in the first step.The fate of (I) under various conditions is discussed.Finally, the features of the oxidation of thioethers by peroxyacylnitrate are compared with those of acyl peroxides and peroxy esters.It is suggested that in each case formation of a sulfurane may well be the first step.
- Noort, Paul C. M. van,Vermeeren, Hans P. W.,Louw, Robert
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p. 312 - 321
(2007/10/02)
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