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排序方式: 共有196条查询结果,搜索用时 218 毫秒
101.
Hiranthi Jayasuriya KithsiriB. Herath Chaowei Zhang DeborahL. Zink Angela Basilio Olga Genilloud MariaTeresa Diez Francisca Vicente Ignacio Gonzalez Oscar Salazar Fernando Pelaez Richard Cummings Sookhee Ha Jun Wang SheoB. Singh 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2007,119(25):4768-4772
102.
103.
Jenkins AD Herath A Song M Montgomery J 《Journal of the American Chemical Society》2011,133(36):14460-14466
Strategies for the reductive cycloaddition of enals or enoates with alkynes have been developed. The enal-alkyne cycloaddition directly affords cyclopentenols, whereas the enoate-alkyne cycloaddition affords the analogous cyclopentenones. The mechanism of these processes likely involves formation and protonation of a metallacyclic intermediate. The general strategy provides a straightforward entry to five-membered ring products from simple, stable π-systems. 相似文献
104.
We present a direct current slice imaging study of tetrachloroethylene (C(2)Cl(4)) photodissociation, probing the resulting ground state Cl ((2)P(3/2)) and spin-orbit excited state Cl* ((2)P(1/2)) products. We report photofragment images, total translational energy distributions and the product branching ratio of Cl*/Cl following dissociation at 235 and 202 nm, obtained using a two-color reduced-Doppler dissociation/probe. Near 235 nm, the Cl translational energy distribution shows a peak at the limit of the available energy, indicating a direct dissociation through a σ*(C-Cl) ← π (C=C) transition, which is superimposed on a broader underlying distribution. The ground state Cl image and associated translational energy distribution at 202 nm is broad and peaked at lower energy, suggesting either internal conversion to the ground state or a lower excited state prior to dissociation. The Cl* images are similarly broad at both wavelengths. The branching ratio is presented as a function of recoil energy, but after integration shows a near-statistical average of Cl:Cl* as 70:30 at both wavelengths. All the images are largely isotropic, with anisotropy parameters (β) of 0.05 ± 0.03. 相似文献
105.
Oligomerizations of renewable resources based monomers levulinic acid, and glycerol were studied using three different catalysts, Sb2O3, p-toluenesulfonic acid, and 1-(1-propylsulfonic)-3-methylimidazolium chloride. The highest average degree of oligomerization of 9.8 was achieved by heating an equimolar mixture of levulinic acid, and glycerol first from 23 to 210 °C under a nitrogen atmosphere for 1 h, and then at 210 °C under a vacuum for 9 h, in the presence of 1.0 mol% Sb2O3 catalyst. p-Toluenesulfonic acid, and 1-(1-propylsulfonic)-3-methylimidazolium chloride catalyzed reactions gave oligomers with relatively lower molecular weights. These levulinic acid–glycerol oligomers are shown to have ketal and ester links in a linear oligomer chain by using 1H and 13C NMR spectroscopy. Three different types of terminal units: keto, glycerol-ketal, and glycerol-ester were identified with the help of model compounds, and their relative percentages were calculated using quantitative 1H and 13C NMR data. 相似文献
106.
We report an imaging study of nitric acid (HNO(3)) photodissociation near 204 nm with detection of O((1)D), one of the major decomposition products in this region. The images show structure reflecting the vibrational distribution of the HONO coproduct and significant angular anisotropy that varies with recoil speed. The images also show substantial alignment of the O((1)D) orbital, which is analyzed using an approximate treatment that reveals that the polarization is dominated by incoherent, high order contributions. The results offer additional insight into the dynamics of the dissociation of nitric acid through the S(3) (2 (1)A(')) excited state, resolving an inconsistency in previously reported angular distributions, and pointing the way to future studies of the angular momentum polarization. 相似文献
107.
Behzad Shahmoradi K. Namratha K. Byrappa K. Soga S. Ananda R. Somashekar 《Research on Chemical Intermediates》2011,37(2-5):329-340
ZnO nanoparticles were synthesized under mild hydrothermal conditions (T = 150 °C, P = autogenous, experimental duration = 18 h). Manganese was added as an additive to ZnO nanoparticles in different molar percentages. In situ surface-modification was successfully carried out for these manganese-added ZnO nanoparticles using n-butylamine as a surface modifier. The modified manganese-added ZnO nanoparticulates are hydrophilic in nature and are well dispersed in various solvents. The modified nanoparticles were characterized using powder XRD, FTIR, SEM, Zeta potential, and UV?CVis spectrophotometry. The characterization results indicated tailoring of the morphology and size of the nanoparticles, and changing the surface chemistry of the nanoparticles synthesized. The SEM results show that the surface modified manganese-added ZnO nanoparticles have a very thin layer of organic coverage around the inorganic nanoparticles, thus, giving rise to hybrid nanoparticles. The photodegradation of Brilliant Blue dye under sunlight showed the higher efficiency of the modified manganese-doped ZnO nanoparticles compared to the reagent-grade ZnO. 相似文献
108.
B. M. Venkatesha R. T. Radhika S. Ananda K. Byrappa 《Research on Chemical Intermediates》2011,37(2-5):195-199
Decolorization of indigo caramine dye by oxidation process using chloramine-T as oxidant and Co(II) as catalyst in acidic buffer media, pH 5.8 has been kinetically studied at 300 K. Decolorization of indigo caramine dye was followed spectrophotometrically. Decolorization and oxidation led to a decrease in Chemical Oxygen Demand of the dye. The Co(II)-catalyzed reaction shows first-order dependence of the rate on chloramine-T and indigo caramine concentrations. It also shows fractional order dependence on [Co(II)] and [H+]. Addition of halide ions or reduction product of chloramine-T toluenesulfonamide, and variation of ionic strength and dielectric constant of the medium do not have any significant effect on the reaction rate. Activation parameters are evaluated from the Arrhenius plot, and a mechanism is proposed for the reaction. 相似文献
109.
Patil Audumbar Mane Ananda Kamat Siddharth Lohar Trushant Salunkhe Rajashri 《Research on Chemical Intermediates》2019,45(6):3441-3452
Research on Chemical Intermediates - From the green chemistry point of view, water is one of the most sustainable solvents for chemical transformations, but there are some limitations to its use as... 相似文献
110.