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31.
《Analytical letters》2012,45(9):1028-1035
This paper reported a headspace gas chromatographic (HS-GC) method for the determination of ethoxyl in ethyl cellulose. A 0.5 mL sample of hydroiodic acid (57%) was added to ~20 mg samples in a closed headspace test vial (20mL) for 30 min at 120°C, for the quantitative cleavage of ethoxyl with hydroiodic acid (HI) to form ethyl iodide. After the reaction, the excess amount of HI in the vial was neutralized by injecting a sodium hydroxide solution, and then the ethyl iodide in the vial was determined by headspace gas chromatography using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD <0.5%) and accuracy (recovery = 98.6 ± 0.5%) for the quantification of ethoxyl content in ethyl celluloses. The present method is simple and accurate, which can be used for the efficient determination of ethoxyl substitution in ethyl cellulose related research. 相似文献
32.
Easily prepared choline iodide is an active catalyst for the synthesis of cyclic carbonates through the coupling reaction of CO2 and epoxides using low pressure (1 MPa), moderate temperature (85 ºC) and green solvents (ethanol and propan-2-ol). The effects of reaction temperature, pressure, reaction time and amount of catalyst used were also investigated. The results showed moderate to high yields and excellent selectivities of cyclic carbonates with vinyl or acrylate groups under mild reaction conditions. The heterogenization of choline over a Merrifield resin gives access to a supported catalyst with good recyclability and reactivity that can be extended to a variety of terminal epoxide substrates. 相似文献
33.
M. Reháková A. Sopková J. Lokaj 《Journal of inclusion phenomena and macrocyclic chemistry》1992,14(1):47-54
The aim of this study was the preparation of natural zeolitic materials doped with iodine and its ions. Natural zeolite from an East Slovakian deposit was used. The content of iodine in the zeolitic products depended on the experimental conditions used for the preparation. The products and their intermediates obtained at 100, 200, 400 and 900°C were identified. 相似文献
34.
35.
Ti(IV) as TiCl3(O3SCF3) and TiO(O2CCF3)2 are used as efficient catalysts for oxidative coupling of aliphatic, aromatic and heteroaromatic thiols to their disulfides in the presence of NaI under air atmosphere. 相似文献
36.
建立了二维离子色谱法同时测定环境水样中的碘离子、硫氰酸根离子和高氯酸根离子的方法。先采用常规阴离子色谱柱(IonPac AS16, 250 mm×4 mm)将水样中的碘离子、硫氰酸根离子和高氯酸根离子与干扰离子进行分离。样品溶液通过抑制器后,将含有碘离子、硫氰酸根离子和高氯酸根离子的淋洗液导入富集柱(MAC-200, 80 mm×0.75 mm),再通过毛细管阴离子色谱柱(IonPac AS20 Capillary, 250 mm×0.4 mm)进行分离和定量分析。方法的线性范围为0.05~100 μg/L,相关系数达到0.9999,检出限为0.02~0.05 μg/L。样品中碘离子、硫氰酸根离子和高氯酸根离子的加标回收率在85.1%~100.1%之间,回收率的相对标准偏差(RSD)(n=6)在1.7%~4.9%之间。该法试剂用量小,灵敏度比常规离子色谱提高30~40倍,同时去除了样液中的高浓度基体杂质,适用于水样中低含量碘离子、硫氰酸根离子和高氯酸根离子的检测。 相似文献
37.
The X-ray structure of H2T(3-Py)P·HgI2·C60, cocrystallized from a chlorobenzene/methanol solvent mixture containing 5,10,15,20- tetra(3-pyridyl)porphyrin, HgI2 and C60, has been determined. A new two dimensional arrangement of the tetra(3-pyridyl)porphyrin molecules joined by coordination to HgI2 is formed. These assemblies are connected by close C60-porphyrin π–π interactions leading to the alignment of the porphyrins into linear alternating fullerene porphyrin columns. The structure is compact with no significant cavities. 相似文献
38.
Richard J CohenDaniel L Fox Jarrod F EubankRalph Nicholas Salvatore 《Tetrahedron letters》2003,44(47):8617-8621
A mild and convenient synthesis for phosphonates using cesium carbonate (Cs2CO3), tetrabutylammonium iodide (TBAI) and DMF was developed at room temperature. Numerous dialkyl phosphites were screened using a diverse array of alkyl halides and these reaction conditions were found to be highly efficient producing various phosphonates exclusively in moderate to high yields. 相似文献
39.
Kaname TsuchiiAkiya Ogawa 《Tetrahedron letters》2003,44(49):8777-8780
Upon irradiation through Pyrex with a xenon lamp (hν>300 nm), terminal acetylenes undergo highly selective selenoperfluoroalkylation with perfluoroalkyl iodide and diphenyl diselenide. In this reaction, perfluoroalkyl and phenylseleno groups are selectively introduced into the terminal and internal positions of acetylenes, respectively. 相似文献
40.
Ion hydration has been studied for potassium iodide solutions with concentrations from 0 to 51 wt.% at temperatures from 288.15 to 308.15 K based on ultrasonic measurements and molar adiabatic compressibility data. For hydration complexes, structural characteristics have been determined. The structure of noncoordinated water plays a significant role even in concentrated solutions. An electrostatic ion field has a strong effect on the temperature dependence of the molar volume of hydration water. A method for the precise determination of the total solvation boundary is presented. 相似文献