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921.
Bao-Min Wang Zhang Yuan Zhi-Qiang Guo Hai-Nan Ma Chuan Fook Lai 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(13):2253-2259
As a new nano-scale functional material, it is necessary to achieve a uniform distribution in the composites for gaining the CNFs’ excellent reinforcing effect. In this paper, CNFs were purified by the method of high temperature annealing treatment. Six surfactants, methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), sodium dodecyl sulfate (SDS), dodecylamine (DDA), N, N-dimethyl formamide (DMF) and cetyltrimethyl ammonium bromide (CTAB) were used individually and combinatorially in a certain concentration to disperse the CNFs in aqueous solution. To achieve a good dispersion of the CNFs, a method utilizing ultrasonic processing was employed. The CNFs treated by the method of high temperature annealing treatment were characterized by differential thermal analysis (DTA) and thermogravimetry analysis (TGA), and the ultrasonication-driven dispersion of CNFs in aqueous solutions were monitored by UVvis spectroscopy and transmission electron microscopy (TEM). The experiments reveal that the method of high temperature annealing treatment purified the CNFs and the maximum achievable dispersion of CNFs corresponds to the maximum UV absorbance of the solution. All results show that the surfactants mixture of MC and SDS in a certain concentration of 0.4 and 2.0 g/L has the maximum dispersion effect on CNFs in aqueous solution, the optimum concentration ratio of MC, SDS, and CNFs was 2: 10: 1. 相似文献
922.
Copper-catalyzed selective methylthiomethylation of 1,4-disubstituted 1,2,3-triazole phenols using DMSO as a methylthiomethylation reagent was achieved. Controlled by the triazole ring, the ortho-phenolic hydroxyl in N(1) aryl can be selectively methylthiomethylated, generating functionalized 1,4-disubstituted 1,2,3-triazoles bearing aryl methylthiomethyl ether fragment. 相似文献
923.
An improved, mild procedure for the CuI‐catalyzed coupling reactions of aryl iodides with aliphatic and aromatic thiols, using L ‐proline as the ligand, is reported. This procedure is noteworthy given its high generality and exceptional level of functional group toleration. 相似文献
924.
4-Substituted tetrahydro-3,6-pyridazinedione 3-hydrazones (2) (or their 3-hydrazino tautomers 3), useful intermediates in the synthesis of bicyclic pyridazine derivatives, were prepared in satisfactory yields in the reaction of the corresponding alkyl 3-substituted 3-cyanopropionates with hydrazine hydrate. 相似文献
925.
Ethynylferrocene was prepared in satisfactory yield by reaction of formylferrocene with triphenylphosphine and carbon tetrachloride followed by dehydrohalogenation in presence of n-butyllithum. The reaction condition is mild and the reaction time is much shorter. The method is convenient and economical. 相似文献
926.
Dengxue Ma Qiying Xia Guangfu Ji 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(12):2047-2053
To look for the single-source precursors, density functional theory calculations were performed to study structures, IR spectra, and stabilities of the possible isomers for the clusters (I2GaN3) n (n = 1–4). It is found that the optimized (I2GaN3) n (n = 2–4) clusters all possess cyclic structure containing Ga-Nα-Ga linkages, and azido group in azides has linear structure. Trends in geometrical parameters with the oligomerization degree n are discussed. The IR spectra are obtained and assigned by vibrational analysis. Thermodynamic properties are linearly correlated with the oligomerization degree n as well as the temperature. Mean-while, the oligomerizations can occur spontaneously at 298.2 K. 相似文献
927.
One‐pot reactions to produce 2,2′:6′,2″‐terpyridine (tpy) under mild conditions are described under both solventless and solvent‐assisted conditions. Tpy can be obtained in 32% yield in a simple one‐pot reaction, which can readily be scaled‐up to give large quantities of tpy. These new approaches are superior to those previously described because of the fast and efficient synthesis and purification of tpy. 相似文献
928.
A selective and effective oxidation of alcohols into the corresponding aldehydes and ketones, respectively, with a new reagent, ferric(III) nitrate supported on kieselguhr, under heterogeneous conditions is reported. 相似文献
929.
Michaela Mačková Michal Himl Jan Budka Michaela Pojarová Ivana Císařová Václav Eigner Petra Cuřínová Hana Dvořáková Pavel Lhoták 《Tetrahedron》2013,69(4):1397-1402
Methylation of 5,11,17,23-tetranitrothiacalix[4]arene with diazomethane leads to the tetramethoxy derivative, which was studied using single-crystal X-ray crystallography. It revealed that this compound, albeit in the 1,3-alternate conformation, can form the inclusion complexes with various solvent molecules possessing acidic methyl groups (ethyl acetate, nitromethane, acetone, acetonitrile) and creates interesting infinite channels filled with solvent molecules. The subsequent transformation of nitro groups into the ureido moieties gave receptors capable of anion recognition even in a highly HB-competitive solvent like DMSO. 相似文献
930.
Reaction of chiral allylic cyclic carbonates with Grignards reagent in the presence of NiCl2(dppe) as a catalyst afforded the alkylated (E)-allylic alcohols with high regio- and diastereoselectivity. 相似文献