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71.
Electrochemical oxidation of benzenediols (1--4) has been studied in the presence of dibenzoylmethane (5) as a nucleophile using cyclic voltammetry and controlled-potential coulometry. The results indicate that the electrochemically generated quinones participate in Michael addition reaction with 5 via various mechanisms to produce new benzofuran derivatives. We derived various products based on electrochemical oxidation in the controlled potential condition, at carbon electrode without toxic reagents in an undivided cell and ambient condition. 相似文献
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A higher-order nonlocal strain-gradient model is presented for the damped vibration analysis of single-layer graphene sheets (SLGSs) in hygrothermal environment. Based on Kirchhoff plate theory in conjunction with a higher-order (bi-Helmholtz) nonlocal strain gradient theory, the equations of motion are obtained using Hamilton's principle. The higher-order nonlocal strain gradient theory has lower- and higher-order nonlocal parameters and a material characteristic parameter. The presented model can reasonably interpret the softening effects of the SLGS, and indicates a reasonably good match with the experimental flexural frequencies. Finally, the roles of viscous and structural damping coefficients, small-scale parameters, hygrothermal environment and elastic foundation on the vibrational responses of SLGSs are studied in detail. 相似文献
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In aqueous solution containing azide ion as a nucleophile, electrochemical oxidation of hydroquinone and some dihydroxybenzoic acids have been studied using cyclic voltammetry and controlled-potential coulometry. The voltammetric data show that electrochemically generated para and ortho-benzoquinones participate in Michael addition reactions with azide ions to form the corresponding diazido or diaminobenzoquinones. In this work, we have proposed various mechanisms for the electrode process and we report an efficient and one-pot method for the synthesis of 2,5-diazido-1,4-benzoquinone, 2,5-diamino-1,4-benzoquinone, 4,5-diamino-1,2-benzoquinone, and 2,3-diamino-5,6-dioxocyclohexa-1,3-dienecarboxylic acid based on the Michael reaction of electrochemically generated ortho and para-benzoquinones with azide ion in an undivided cell using an environmentally friendly reagent-less method in ambient conditions. An estimation of the observed homogeneous rate constant (kobs) of the reaction of electrochemically generated para-benzoquinone with azide ion by the digital simulation method is also presented. 相似文献
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The reaction of electrochemically generated anthradiquinone as a Michael acceptor with 2-mercaptobenzothiazole and 2- mercaptobenzoxazole,as nucleophiles in ethanol/water mixtures has been studied by means of cyclic voltammetry.Our voltammetric data indicate that produced anthradiquinone participates in Michael addition reaction with nucleophiles and via an ECEC mechanism converts to the new anthraquinonethioether derivatives.Based on an EC mechanism,the observed homogeneous rate constant of the Michael reaction of anthradiquinone with nucleophiles were estimated by comparing the experimental cyclic voltammograms with the digital simulated results. 相似文献
75.
In this study, indium tin oxide (ITO) thin films were prepared by electron beam deposition method on glass substrates at room temperature (RT). Surface morphology characterization of ITO thin films, before and after annealing at 500 °C, were investigated by analyzing the surface profile of atomic force microscopy (AFM) images using wavelet transform formalism. The wavelet coefficients related to the thin film surface profiles have been calculated, and then roughness exponent (α) of the films has been estimated using the scalegram method. The results reveal that the surface profiles of the films before and after annealing process have self-affine nature. 相似文献
76.
Davood Habibi Mohammad Ali Zolfigol Ali Reza Faraji Payam Rahmani 《Monatshefte für Chemie / Chemical Monthly》2012,37(1):809-814
Abstract
Tribromoisocyanuric acid/wet SiO2 was used for the conversion of C=N bonds to their corresponding carbonyl compounds in oximes, semicarbazones, azines, and Schiff bases. The interesting feature of this system is that in those oximes, semicarbazones, azines, and Schiff bases which have conjugated or unconjugated C=C bonds, the C=N bond will selectively change to the relevant C=O bond while the conjugated or unconjugated C=C bond will remain intact. 相似文献77.
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