A new phenacyl‐type photoinitiator based on ethyl carbazole as a long wavelength photoinitiator is developed for free radical polymerization. Phenacyl ethyl carbazolium hexafluoroantimonate (PECH) photoinitiator is synthesized in a two‐step, one‐pot manner by quaternizing ethyl carbazole with phenacyl bromide and subsequent ion exchange reaction with potassium hexafluoroantimonate. Under irradiation, PECH tends to undergo homolytic bond cleavage bringing about initiating free radicals. However, as evidenced by cyclic voltammetry and real‐time photobleaching studies, formation of initiating cationic species is highly unlikely as the photochemically formed charged carbazole units tend to couple.
A simple, efficient and general two step procedure, through a sequential Ugi reaction followed by a Bischler–Napieralski/heterocyclization tandem closure, to give novel 6,11-dihydro-5H-imidazo[1′,5′:1,2]pyrido[3,4-b]indol-2-ium salt derivatives, is described. By changing the amine and the acid components with ammonium formate, the same procedure affords 6,11-dihydro-5H-imidazo[1′,5′:1,2]pyrido[3,4-b]indole derivatives. 相似文献
A series of sulfonium tetraphenylborates can be readily prepared by the metathesis of sulfonium halides with sodium tetraphenylborates. After heating at 120–150 °C, the sulfonium tetraphenylborates can smoothly undergo the cross-couplings between the tetraphenylborate anions and the sulfonium cations in the absence of a metal catalyst. For carbonylmethyl-, benzyl-, and allylsulfoniums, the corresponding carbonylmethyl–phenyl, benzyl–phenyl, and allyl–phenyl cross-coupling products can be obtained in 22–76% yields. An interionic electron-transfer mechanism for this cross-coupling reaction is proposed. 相似文献
Epoxypropyl dodecyl dimethyl ammonium chloride (EPDDMAC) was synthesized with N,N-dimethyl dodecyl amine (DMDA) and epichlorohydrin (EPIC). Diethyl-2,3-epoxypropyl-[3-methyldimethoxyl)] silpropyl ammonium chloride (DEEPSAC) was synthesized with N,N-diethyl-aminopropyl-methyldimethoxysilane (DEAPMDES) and epichlorohydrin (EPIC). The products were characterized by infrared and elemental analysis and 1H NMR spectroscopy. The surface tension, conductivity, and antibacterial activities of EPDDMAC and DEEPSAC were studied. 相似文献
The layer-by-layer electrostatic deposition method is a novel technique to precisely control the interfacial properties of multilayered films such as charge, thickness, permeability, and composition. The formation and stability of multilayered emulsions is however often plagued by extensive droplet flocculation and aggregation even at ideal polyelectrolyte concentrations where saturation should occur. Addition of salts may reduce the degree of attractive interactions ions and thus improve deposition. To test this hypothesis, the influence of different Hofmeister salts (KCl, NaCl, LiCl, and NH4Cl) at various salt concentrations (0–2500 mM) on the aggregation behavior of multilayered emulsions was investigated. A simple coating process of fish gelatin interfacial membranes with sugar beet pectin was used. Our results show that mean particle diameter and particle size distribution of emulsions initially decreased from 600 nm to 328 nm with increasing salt concentrations up to 250 mM. Above a critical level (>500 mM), heavy aggregation of emulsions at the presence of chaotropic salts occurred whereas kosmotropes reduced flocculation and creaming. Microscopic images and isothermal titration calorimetry confirmed particle size measurements. Results thus suggest that addition of salts may be an extremely useful tool to modulate and improve depositioning of alternatingly charged polymers on surfaces. 相似文献
A new approach for the preparation of copper nanooxide by solvothermal decomposition of N, N′‐dinitrourea copper(II) salt in an aprotic solvent was developed. The resulting particles were studied by transmission electron microscopy, X‐ray photoelectron spectroscopy, and small‐angle X‐ray scattering. The effects of different solvents on shapes of the agglomerates formed are shown. 相似文献
An experimental investigation of single helium bubbles rising in a stagnant molten fluoride salt mixture was conducted in a 25.4 mm quartz tube at 600 °C and atmospheric pressure. The fluoride salt chosen for this research was the eutectic mixture of LiF-NaF-KF (46.5–11.5–42%), also known as FLiNaK. The images obtained using a high-speed camera were processed to estimate the bubble size, rising velocity, trajectory and shape. The shape of the bubble showed typical characteristics of wobbling bubble corresponding to published classifications. The trajectory of the rising bubble showed complex path oscillations and combinations of rectilinear, zig-zag and helical motion. The projected area-equivalent diameter and experimental terminal velocity varied from 5.26 to 6.23 mm and 232.35–259.57 mm/s, respectively. Several important dimensionless numbers were calculated and reported based on the experimental results, which are closely related to the phenomena involving a gas bubble rising in liquid. The measured terminal velocity was compared with the predictions of existing correlations that include the dimensionless numbers and showed reasonable agreement. The Particle Image Velocimetry (PIV) technique was applied to complement the experimental data set with high-fidelity measurements of the velocity field of the liquid molten salt surrounding the bubble. The paper presents a unique set of PIV and two-phase experimental data capturing the behavior of rising helium bubbles in molten FLiNaK and its surrounding flow field. 相似文献
Perovskite La0.8Sr0.2Co0.2Cr0.8O3 − δ (LSCC) ceramic synthesized by the conventional ceramic processing technique was studied as a novel coating material for the cathode current collector in Na/S battery. Its structure, electrical conductivity, density and thermal expansion coefficient (TEC) were investigated. The corrosion performance of LSCC was in particular evaluated by electrochemical techniques in combination with long-term dip-immersion tests. The results indicated that LSCC exhibited excellent corrosion resistance in molten sodium tetrasulfide at 350 °C. The corrosion current density icorr (0.081 mA cm− 2) was much lower than that of 316 L stainless steel by approximately two orders of magnitude. The corrosion rate of LSCC deduced from immersion test was as low as about 12 μm year− 1. 相似文献
There is anecdotal evidence for the significant effects of salt ions on the flotation separation of minerals using process water of high salt content. Examples include flotation of soluble salt minerals such as potash, trona and borax in brine solutions using alkylammonium and alkylsulfate collectors such as dodecylamine hydrochloride and sodium dodecylsulfate. Although some of the effects are expected, some do not seem to be encompassed by classical theories of colloid science. Several experimental and modeling techniques for determining solution viscosity, surface tension, bubble-particle attachment time, contact angle, and molecular dynamics simulation have been used to provide further information on air–solution and solid–solution interfacial phenomena, especially with respect to the interfacial water structure due to the presence of dissolved ions. In addition atomic force microscopy, and sum frequency generation vibrational spectroscopy have been used to provide further information on surface states. These studies indicate that the ion specificity effect is the most significant factor influencing flotation in brine solutions. 相似文献