complex synthesis

  • 文章类型: Journal Article
    研究了在[C8mim][NTf2]离子液体中使用苯并-15-冠-5醚(B15C5)作为萃取剂从LiNTf2和LiCl盐的水溶液中萃取锂的方法。确定了萃取剂向水相中的转变以及从LiCl溶液中萃取锂的过程中Cl-离子的分布。首次分离出具有不同LiNTf2:B15C5比例的LiNTf2与B15C5的配合物,并通过X射线衍射和红外光谱进行了表征。通过萃取系统的红外光谱研究确定了LiCl和LiNTf2萃取过程的差异。
    The extraction of lithium from aqueous solutions of LiNTf2 and LiCl salts using benzo-15-crown-5 ether (B15C5) as an extractant in [C8mim][NTf2] ionic liquid was studied. The transition of the extractant into the aqueous phase and the distribution of Cl- ions during lithium extraction from LiCl solutions were determined. LiNTf2 complexes with B15C5 with different LiNTf2:B15C5 ratios were isolated for the first time and characterized via X-ray diffraction and IR spectroscopy. Differences in the extraction process of LiCl and LiNTf2 were determined via an infrared spectroscopic study of the extraction systems.
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  • 文章类型: Journal Article
    尽管最近在非外消旋地制备它们的合成方法方面取得了进展,但手性烯丙基羰基化合物如烯丙酯在复合物合成中仍未得到充分利用。该领域现在已经成熟,可以使用此类丙二烯类作为构建块,以促进复杂的小分子化合物的构建,比如桥接自行车。
    Chiral allenylcarbonyls such as allenoates remain underutilized in complex synthesis despite recent advances in synthesis methods to prepare them non-racemically. The field is now ripe for the employment of this class of allenes as building blocks to facilitate the construction of complex small-molecule compounds, such as bridged bicycles.
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  • 文章类型: Journal Article
    已经确定,水杨酸异丙酯可以与1,3-二酮类似地用作选择性分离碱金属阳离子的新型高效萃取系统的关键成分。根据水杨酸异丙酯和1,3-二酮与碱金属阳离子(Li,Na+,K+),形成六元金属环,其稳定性沿Li>Na>K系列降低,这导致观察到的增强的对锂的亲和力。水杨酸异丙酯的萃取能力在三辛基氧化膦(TOPO)存在下表现出来。通过FT-IR表征了新获得的水杨酸异丙酯与碱金属阳离子的配合物以及它们与TOPO的混合物中的提取物,拉曼,和NMR光谱。推测了提取的锂络合物的可能结构,并详细研究了TOPO在提取过程中的作用。萃取实验表明,从模型多组分溶液中萃取时,Li/Na和Li/K对的分离系数极高。
    It was established that isopropyl salicylate can be used similarly to 1,3-diketones as a key component for a new efficient extraction system for selective separation of alkali metal cations. According to DFT modeling of complexes of isopropyl salicylate and 1,3-diketone with alkali metal cations (Li+, Na+, K+), six-membered metallacycles are formed whose stability decreases along the series Li > Na > K, which results in the observed enhanced affinity to lithium. The extraction ability of isopropyl salicylate is manifested in the presence of trioctylphosphine oxide (TOPO). The newly obtained complexes of isopropyl salicylate with alkali metal cations as well as their extracts in a mixture with TOPO are characterized by means of FT-IR, Raman, and NMR spectroscopy. The probable structure of the extracted lithium complex is presumed and the role of TOPO in the extraction process is investigated in detail. Extraction experiments showed extremely high separation coefficients for Li/Na and Li/K pairs in the extraction from a model multi-component solution.
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  • 文章类型: Journal Article
    本文介绍了来自多个研究的个体参与者数据(IPD)的元分析中介分析方法。中介分析评估干预对健康结果的有效性是否由于干预所针对的关键行为的变化而发生。然而,个别试验通常在统计学上不足以检验调解假说.在元分析背景下评估调解的现有方法受到它们对汇总数据的依赖的限制;因此,研究结果可能与与感兴趣途径无关的研究水平差异相混淆.为了克服现有元分析调解方法的局限性,我们使用结构方程模型(SEM)的一阶段估计方法,将来自多项研究的IPD结合起来进行中介分析.这种方法(1)说明了研究中参与者的聚集,(2)通过多重插补来容纳缺失的数据,和(3)允许关于间接(即,通过自举置信区间介导)效应。我们使用了来自INTEGRATE项目的数据(来自10项研究的N=3691)(Mun等人。成瘾行为心理学,29,34-48,2015),通过测试使用保护性行为策略的改进是否介导了大学生对酒精相关问题的简短动机干预的有效性,来说明SEM方法进行荟萃分析调解分析。为了促进方法的应用,我们在R中提供带注释的计算机代码和用于复制的数据。在实质性层面,独立的个性化反馈干预通过更多地使用保护性行为策略来减少酒精相关问题;然而,跨策略的净中介效应规模较小,平均而言。
    This paper introduces a meta-analytic mediation analysis approach for individual participant data (IPD) from multiple studies. Mediation analysis evaluates whether the effectiveness of an intervention on health outcomes occurs because of change in a key behavior targeted by the intervention. However, individual trials are often statistically underpowered to test mediation hypotheses. Existing approaches for evaluating mediation in the meta-analytic context are limited by their reliance on aggregate data; thus, findings may be confounded with study-level differences unrelated to the pathway of interest. To overcome the limitations of existing meta-analytic mediation approaches, we used a one-stage estimation approach using structural equation modeling (SEM) to combine IPD from multiple studies for mediation analysis. This approach (1) accounts for the clustering of participants within studies, (2) accommodates missing data via multiple imputation, and (3) allows valid inferences about the indirect (i.e., mediated) effects via bootstrapped confidence intervals. We used data (N = 3691 from 10 studies) from Project INTEGRATE (Mun et al. Psychology of Addictive Behaviors, 29, 34-48, 2015) to illustrate the SEM approach to meta-analytic mediation analysis by testing whether improvements in the use of protective behavioral strategies mediate the effectiveness of brief motivational interventions for alcohol-related problems among college students. To facilitate the application of the methodology, we provide annotated computer code in R and data for replication. At a substantive level, stand-alone personalized feedback interventions reduced alcohol-related problems via greater use of protective behavioral strategies; however, the net-mediated effect across strategies was small in size, on average.
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  • 文章类型: Journal Article
    一罐协议,用元素溴进行14倍溴化,提供了铜β-八溴-内消旋-三(2,6-二溴-3,5-二甲氧基苯基)吡咯,一种新的双袋装金属键。铜配合物在还原条件下经历了平滑的脱金属,提供游离的Corrole配体,进而可以容易地与MnIII和AuIII络合。获得MnIII配合物的单晶X射线结构。
    A one-pot protocol, effecting 14-fold bromination with elemental bromine, has afforded copper β-octabromo-meso-tris(2,6-dibromo-3,5-dimethoxyphenyl)corrole, a new bis-pocket metallocorrole. The Cu complex underwent smooth demetalation under reductive conditions, affording the free corrole ligand, which in turn could be readily complexed to MnIII and AuIII. A single-crystal X-ray structure was obtained for the MnIII complex.
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