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51.
Smith AA Drake MD Rahim AK Roberts JD 《The journal of physical chemistry. A》2008,112(48):12367-12371
A value of 74(+/-4) degrees was determined from NMR-observed dipolar couplings for the rotational dihedral angle of the monosuccinate anion in an aprotic liquid-crystal solution of the gauche conformation of tetraoctylammonium monosuccinate. This value is in reasonable agreement with other, somewhat less definitive, evidence gleaned from isotropic vicinal proton-proton couplings of the essentially completely gauche preference of the monosuccinate anion in tert-butyl alcohol and aprotic solvents, such as DMSO and THF, and quantum computations for the monoanion in THF. 相似文献
52.
Rahmat Sadeghi Rahim Hosseini 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):177-185
The volumetric, compressibility and electrical conductivity properties of sodium n-heptyl sulfonate (C7SO3Na) in pure water and in aqueous poly(ethylene glycol) (PEG) solutions were determined at different temperatures below and above the micellar composition range. At each temperature, the infinite dilution apparent molar volumes of the monomer and micellar state of C7SO3Na in aqueous PEG solutions respectively are smaller and larger than those in pure water. However, the values of the infinite dilution apparent molar isentropic compressibility of both monomer and micellar states of C7SO3Na in aqueous PEG solutions are larger than those in pure water. Thermodynamic parameters of micellization of investigated surfactant in water and in aqueous solutions of PEG at different temperatures were estimated and it was found that the micelle formation process is endothermic and therefore, this process must be driven by entropy increase. The calculated Gibbs free energies of micellization for aqueous PEG solutions are more negative than those for pure water and become more negative by increasing temperature. The variation of the critical micelle concentration (CMC) of C7SO3Na in water and in aqueous PEG solutions with temperature was obtained and a comparison between the CMC of C7SO3Na obtained from different thermodynamic properties was also made. 相似文献
53.
Mojgan Kargar Rahim Hekmatshoar AbdolJalil Mostashari 《Journal of the Iranian Chemical Society》2012,9(4):483-488
Tandem Michael addition/elimination/Michael addition/cyclization reactions of diethyl ethoxymethylenemalonate as a double Michael acceptor with cyclic ??-diketones furnished novel 9-substituted 1,8-dioxooctahydroxanthenes. 相似文献
54.
Khalid Mohammed Khan Muhammad Taha Fazal Rahim Waqas Jamil Shahnaz Perveen Muhammad Iqbal Choudhary 《Journal of the Iranian Chemical Society》2012,9(1):81-83
Treatment of indole with substituted aldehyde in the presence of equimolar amount of sodium bromate and sodium hydrogen sulfite mixture in water yielded corresponding substituted bis(indolyl)methanes in good yields. This provides a facile and environmentally friendly method towards the synthesis of an important class of organic compounds. 相似文献
55.
Rahim MA Islam MS Bae TS Choi WS Noh YY Lee HJ 《Langmuir : the ACS journal of surfaces and colloids》2012,28(22):8486-8495
The mixing of Ag ion-doped poly(ethyleneimine) (PEI) and poly(acrylic acid) (PAA) produced Ag ion-doped polyelectrolyte complex particles (PECs) in solution. Positively charged Ag ion-doped PECs (Ag ion PECs) with a spherical shape were deposited alternatively with PAA to form a multilayer assembly. The multilayered film containing Ag ion PECs was reduced to generate a composite nanostructure. Metal nanoparticle (NP)-enriched nanocomposite films were formed by an additional process of the postadsorption of precursors on PECs within the nanocomposite films, which resulted in the enhancement of the catalytic and electrical properties of the composite films. Because the films contain PECs that are responsive to changes in pH and most of the NPs are embedded in the PECs, interesting catalytic properties, which are unexpected in a particle-type catalyst, were observed upon pH changes. As a result of the reversible structural changes of the films and the immobilization of the NPs within the films, the film-type catalysts showed enhanced performance and stability during catalytic reactions under various pH conditions, compared to particle-type catalysts. 相似文献
56.
Nurulsaidah Abdul Rahim Fabrice Audouin Brendan Twamley Johannes G. Vos Andreas Heise 《European Polymer Journal》2012,48(5):990-996
Well-defined poly(4-vinylpyridine) (P4VP) was synthesised by nitroxide-mediated radical polymerization using the BlocBuilder MAMA-SG1. The controlled character of the polymerization was confirmed by kinetic measurements and linear increase of the molar mass with monomer conversion. Poly(4-vinylpyridine) terminated with SG1 was then used as macroinitiator and chain extended to form poly(4-vinylpyridine-b-methyl methacrylate) and poly(4-vinylpyridine-b-(methyl methacrylate-co-styrene)) block copolymers. These block copolymers spontaneously organized into spherical inverse micelles in THF with critical micelle concentrations of 0.1 mg/mL for poly(4VP190-b-MMA91) and 0.01 mg/mL for poly(4VP190-b-(MMA57-co-S18)) and sizes of 70 and 130 nm (DLS), respectively. The inverse micelles were loaded with copper(II)acetate leading to a slight increase in micelle size. The uniform structure of the inverse micelles was confirmed by FeSEM images, while the presence of copper in the micelle core was established by energy-dispersive X-ray spectroscopy (EDX) and FTIR spectroscopy. 相似文献
57.
Longitudinal spin relaxation due to modulation of dipolar interactions often limits the development of hyperpolarized magnetic tracers. Recently, it has been demonstrated that transferring spin order to a singlet state significantly increases the polarization lifetimes in systems where nitrous oxide is dissolved in a liquid solvent. Additionally, previous studies have suggested that the longitudinal relaxation of nitrous oxide is largely dominated by the spin-rotation interaction. Models of spin-relaxation under Brownian motion nai?vely predict the angular momentum reorienting correlation time of the spin rotation interaction to be inversely proportional to the viscosity of the solution. This dependence implies the singlet lifetime can be lengthened by increasing the dissolving solvent's viscosity-an extension which is not observed. Our work formulates a model which describes the relaxation of nitrous oxide dissolved in various solvents. We investigate the effect of altering the temperature of the solvent, as well as the effect of varying solute-solvent interactions on the singlet state as well as the longitudinal polarization lifetime. We predict the singlet lifetime for nitrous oxide dissolved in several solvents by fitting rotational and angular momentum correlation times measured at high magnetic field, and relate singlet relaxation to translational diffusion constants. 相似文献
58.
59.
Rahim Hekmatshoar Issa Yavari Yahya S. Beheshtiha Majid M. Heravi 《Monatshefte für Chemie / Chemical Monthly》2001,132(6):689-691
Summary. In the presence of metallic zinc, aldehydes and ketones experience reductive coupling in tetrahydrofuran-saturated aqueous
ammonium chloride (5:3) to afford the corresponding pinacols in moderate to high yields.
Received October 23, 2000. Accepted (revised) December 12, 2000 相似文献
60.