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排序方式: 共有227条查询结果,搜索用时 15 毫秒
1.
A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous highsurface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of mass transfer in water/oil biphasic media for the hydroformylation of higher olefins. The catalytic performance for hydroformylation on this biphasic TPPTS-Rh/SiO2 catalyst system was higher than those of the traditional biphasic HRhCO(TPPTS)3 systems, owing to the chemical bonds between the highly dispersed Rh metal particles and the TPPTS ligands. The catalyst system is applicable for hydroformylation of higher olefins such as 1-dodecene. 相似文献
2.
铑(Ⅲ)-钼酸盐-罗丹明B显色体系的研究和应用 总被引:1,自引:0,他引:1
在聚乙烯醇(PVA)存在下,铑(Ⅲ)与钼酸盐和罗丹明B(RB)形成离子缔合物,缔合物的最大吸收位于580nm,摩尔吸光系数ε值1.68×105L·mol-1·cm-1,服从比耳定律范围0~10μgRh/25mL,方法用于催化剂和冶金产品中铑的测定,结果满意 相似文献
3.
4.
Pure rotational transitions of the weakly bound complex He-N(2)O and three minor isotopomers (He-(14)N(15)NO, He-(15)N(14)NO, and He-(15)N(15)NO) were measured in the frequency region from 6 to 20 GHz. Predictions for the microwave transition frequencies were based on the infrared work by Tang and McKellar [J. Chem. Phys. 117, 2586 (2002)]. In the case of (14)N containing isotopomers, nuclear quadrupole hyperfine structure of the rotational transitions was observed and analyzed. The resulting spectroscopic parameters were used to determine geometrical and dynamical information about the complex. An ab initio potential energy surface was calculated at the coupled cluster level of theory with single and double excitations and perturbative inclusion of triple excitations. This surface was constructed using the augmented correlation consistent polarized valence triple zeta basis set for all atoms with the inclusion of bond functions for the van der Waals bond. Bound state calculations were done to determine the energies of low-lying rovibrational levels that are supported by the potential energy surface. The resulting transition energies agree with the experimental values to 1% or better. 相似文献
5.
A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous high-surface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of masstransfer in water/oil biphasic media for the hydroformylation of higher olefins. The catalytic performancefor hydroformylation on this biphasic TPPTS-Rh/SiO2 catalyst system was higher than those of thetraditional biphasic HRhCO(TPPTS)3 systems, owing to the chemical bonds between the highly dispersedRh metal particles and the TPPTS ligands. The catalyst system is applicable for hydroformylation ofhigher olefins such as 1-dodecene. 相似文献
6.
Yunjie Luo Yingming Yao Jinglei Chen Yong Zhang 《Journal of organometallic chemistry》2003,679(1):125-129
Reactions of [N(C6H3i-Pr2-2,6)(SiMe3)]2LnCl(THF) (Ln=Nd, Yb) with two equivalents of MeLi in a mixture solution of toluene and Et2O gave [N(C6H3i-Pr2-2,6)(SiMe3)]2LnCH3(μ-CH3)Li(THF)3·PhCH3 (Ln=Nd (1), Yb (2)) in good isolated yields as crystalline solids. The single-crystal structural analysis of 2 revealed that the coordination geometry of ytterbium ion is best described as a distorted pseudo-tetrahedron. Both 1 and 2 are active for the polymerization of methyl methacrylate to give syndiotactic-rich and high molecular weight polymers (Mn>104) with relatively narrow molecular weight distributions (Mw/Mn<2). 相似文献
7.
The development of catalysts capable of catalyzing amidation of esters with amines to construct amides under mild conditions is of great importance. Compared to aliphatic amines, the direct catalytic amidation of esters with less nucleophilic aromatic amines is rather difficult. Employing simple lanthanide tris (amide) complexes Ln[N (SiMe3)2]3(μ-Cl)Li (THF)3 as the catalysts, it was found a broad range of aromatic amines and esters were efficiently converted into various amides in good yields under mild conditions. A plausible mechanism for this transformation was experimentally supported as starting from an amide exchange reaction between the lanthanide tris (amide) complex and the substrate amine. 相似文献
8.
A library of rare-earth metal derivatives supported by an aminophenoxy ligand was prepared and their catalytic performance in lactide polymerization was investigated. It was found that the synthetic strategy had a profound effect on the formation of aminophenoxy rare-earth metal complexes. Amine elimination between Ln[N(SiMe3)2]3(μ-Cl)Li(THF)3 (Ln = Yb, Y) and 1 equiv. of the aminophenol [HONH] ([HONH] = ο-OCH3-C6H4NHCH2(3,5-tBu2-C6H2-2-OH)) in toluene gave the unexpected heterobimetallic bis(aminophenoxy) rare-earth metal complexes [ON]2LnLi(THF)2 (Ln = Yb ( 1 ), Y ( 2 )). When the reactions were carried out in THF and TMEDA, amine elimination produced the aminophenoxy rare-earth metal amide complexes {[ON]LnN(SiMe3)2}2 (Ln = Yb ( 5 ), Y ( 6 )) in ca 85% isolated yields. Complexes 5 and 6 could also be obtained from salt metathesis reaction of {[ON]LnCl(THF)}2 (Ln = Yb ( 3 ), Y ( 4 )) with NaN(SiMe3)2 in a 1:2 molar ratio. In addition, treatment of complexes 3 and 4 with NaOAr (Ar = &bond;C6H4-4-tBu) and (SiMe3)2NC(NPri)2Na in 1:4 and 1:2 molar ratios provided the corresponding aminophenoxy rare-earth metal derivatives {[ON](μ-OAr)Ln(μ-OAr)Na(THF)2}2 (Ln = Yb ( 7 ), Y ( 8 )) and {[ON]Ln[(iPrN)2CN(SiMe3)2]}2 (Ln = Yb ( 9 ), Y ( 10 )), respectively. These complexes were fully characterized, and their molecular structures were determined using single-crystal X-ray diffraction. Polymerization experiments showed that complexes 1 , 2 , 5 , 6 , 9 and 10 were highly active for the ring-opening polymerization of l -lactide in toluene, and complex 1 promoted l -lactide polymerization in a controlled fashion. The polymerization of rac-lactide initiated by the neutral aminophenoxy rare-earth metal complexes 5 , 6 , 9 and 10 in THF afforded heterotactic polymers. 相似文献
10.
Determination of fatty acids in soil samples by gas chromatography with mass spectrometry coupled with headspace solid‐phase microextraction using a homemade sol–gel fiber† 下载免费PDF全文
Qin Shuai Xiaoxiao Ding Yunjie Huang Shuangshuang Xu Shengrui Xu Qiang Gao Haidong Deng 《Journal of separation science》2014,37(22):3299-3305
Through the use of a homemade sol–gel‐derived fiber, a headspace solid‐phase microextraction technique coupled to gas chromatography with mass spectrometry was developed for the determination of fatty acids with long, even‐numbered carbon chains (C12–C24) in soil samples. The experimental parameters such as reaction time, temperature, and ionic strength that might affect derivatization, extraction, and desorption were investigated. Under the optimized conditions, the linearity of the method ranged from 0.1 to 100 mg/L with a correlation coefficient >0.997. The limit of detection values based on a signal‐to‐noise ratio of 3:1 were determined with the concentration from 0.39 to 39.4 μg/L. The recoveries of the method for the soil samples were from 91.15 to 108.1%. This developed method using a homemade fiber showed a higher sensitivity than that using a commercial polydimethylsiloxane fiber and was also for the analysis of real soil samples from the Paomaling geological park of China. 相似文献