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121.
Summary Direct separations of the enantiomers of cetirizine and related compounds have been achieved by reversed-phase HPLC on the
Chiralcel OD-R, a polysaccharide-derived chiral stationary phase; the mobile phase was usually perchlorate solution supplemented
with acetonitrile. Resolution of the enantiomers of cetirizine and related compounds was good. The effect of the acetonitrile
content of the mobile phase was investigated, and the effect of the structure of the chiral compounds on their behavior on
the Chiralcel OD-R column is discussed. 相似文献
122.
A metal-organic coordination compound formulated as [Cd(MDPPz)(BDC)(H2O)]n 1 (MDPPz=11-methyldipyrido[3,2-a:2',3'-c]phenazine,BDC=1,4-benzenedicarboxylate) has been hydrothermally synthesized and structurally characterized by elemental analysis,IR spectrum,fluorescence spectrum and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system,space group C2/c,with a=30.673(8),b=9.623(3),c=20.784(6) ,β=98.646(3)o,V=6065(3)3,C27H17CdN4O5,Mr=589.85,Dc=1.292 g/cm3,μ(MoKα)=0.757 mm-1,F(000)=2360,Z=8,the final R=0.0381 and wR=0.0855 for 4191 observed reflections (I>2σ(I)). 1 exhibits blue fluorescence property at room temperature. 相似文献
123.
Four lanthanide coordination polymers with benzophenone‐4,4′‐dicarboxylic acid (H2bpndc) and 1,10‐phenanthroline (phen), [Ln2(bpndc)3(phen)] (Ln=La (1), Pr (2) and Tb (3)), [Yb(bpndc)15(phen)].05H2O (4) were obtained through solvothermal synthesis. The crystallographic data show that 1, 2, and 3 are isostructural, the Ln(III) ions in 1, 2 and 3 are all eight‐ and ten‐coordinated, respectively, and thus the Ln(III) ions are connected by bpndc ligands, resulting in an interpenetrating 3D structure. While in 4, the Yb(III) ions are eight‐coordinated and connected by bpndc ligands into a 3D structure with 1D rhombic channels, which result from the effect of lanthanide contraction from La(III) to Yb(III) ions, and the bpndc ligands in 1, 2, 3, and 4 display three types of coordination modes. 相似文献
124.
125.
126.
XinZHANG DeHuaHE QiJiangZHANG BoQingXU QiMingZHU 《中国化学快报》2003,14(10):1066-1069
Comparatively high CH3OH selectivity (60.0%) and yield (6.7%) were obtained on MoOx/(LaCoO3 Co3O4) catalysts in selective oxidation of methane to methanol using molecular oxygen as oxidant. The interaction between MoOx and La-Co-oxide modified the molecular structure of molybdenum oxide and the ratio of O^-/O^2- on the catalyst surface, which controlled the catalytic performance of MoOx/(LaCoO3 Co3O4) catalysts. 相似文献
127.
A kind of inorganic‐organic hybrid 18‐molybdodiphosphate nanoparticles ([(C4H9)4N]6P2Mo18Q62·4H2O) was firstly used as a bulk‐modifier to fabricate a three‐dimensional chemically modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior of the solid nanoparticles dispersed in the CPE in acidic aqueous solution was characterized by cyclic and square‐wave voltammetry. The hybrid 18‐molybdodiphosphate nanoparticles bulk‐modified CPE (MNP‐CPE) displayed a high electrocatalytic activity towards the reduction of nitrite, bromate and hydrogen peroxide. The remarkable advantages of the MNP‐CPE over the traditional polyoxometalates‐modified electrodes are their excellent reproducibility of surface‐renewal and high stability owing to the insolubility of the hybrid 18‐molybdodiphosphate nanoparticles. 相似文献
128.
磷钼钒杂多酸在苯直接羟化反应中的催化作用——O2活化机理的探讨 总被引:2,自引:0,他引:2
磷钼钒杂多酸在有供电子体存在下具有活化氧和使苯直接羟化的催化性能。以抗坏血酸和亚硫酸钠为还原剂的实验表明不同的还原体系吸氧动力学和羟化活性不同。根据氧化还原滴定、循环伏安法、电解还原羟化反应以及光谱实验等测定结果, 对这两个不同体系提出了各自可能的氧的活化机理。认为在以抗坏血酸为还原剂的情况下, 杂多酸阴离子通过三电子传递过程直接络合氧, 氧与阴离子形成中间络合物为控制步骤。在以亚硫酸钠为还原剂的情况下, 供电子体可能先与阴离子络合活化, 直接参与氧的活化过程, 供电子体与阴离子的还原络合为控制步骤。 相似文献
129.
吸热碳氢燃料裂解镧改性混合型催化剂的研究 总被引:3,自引:0,他引:3
制备了吸热型碳氢燃料NNJ-150和镧离子交换改性的USY、ZSM-5分子重申及混合分子筛,考察了NNJ-150在USHY、HZSM-5和两者混合物以及镧改性单分子筛和混合分子筛催化剂上的裂解反应。结果表明,ZSM-5分子筛中添加镧,对NNJ-150的单分子裂解反应有明显影响;混合分子两种分子筛之间存在协同作用,低温(500℃)下,LaUSY LaZSM-5(75:25)混合分子筛对低碳烯烃的选择性较高(41.48%),催化剂寿命较长(35min以上),能有效提高吸热型碳氢燃料NNJ-150的吸热能效。 相似文献
130.
As a natural diterpenoid, crotophorbolone possesses a challenging trans,trans-5/7/6 framework decorated with six contiguous stereogenic centers and is structurally and biogenetically related to tigliane-type diterpenoids with intriguing bioactivities such as phorbol and prostratin. Based on the convergent strategy, we completed an eighteen-step total synthesis of crotophorbolone starting from (−)-carvone and (+)-dimethyl-2,3-O-isopropylidene-l-tartrate. The key elements of the synthesis involve expedient installation of the six-membered ring and the five-membered ring with multiple functional groups at an early stage, cyclization of the seven-membered ring through alkenylation of the ketone between the five-membered ring and the six-membered ring, functional group-sensitive ring-closing metathesis and final selective introduction of hydroxyls at C20 and C4.Convergent total synthesis of crotophorbolone was accomplished in 18 longest linear steps. Observation of unexpected thermodynamic stability of a cis,trans-5/7/6 tricycle would benefit synthetic design of tigliane- and daphnane-related diterpenoids. 相似文献