离子色谱法同时测定水中六种阳离子

研究了用抑制电导离子色谱法一次进样同时测定水中Li^ ,Na^ , NH4^ ,Mg^2 ,Ca^2 的色谱法条件，相对标准偏差小于0．5％，加标回收率在97．5％－104．0％。在水质分析中运用t检验法，比较了用钙、镁离子浓度计算和传统方法测定的总硬度之间是否存在显著性差异。     

Acetic anhydride as a synthetic reagent

Acetic anhydride has been used widely in synthetic organic chemistry, especially in syntheses and transformations of heterocyclic compounds. These utilities are reviewed under the following classification.     

Selective dimerization of α-methylstyrene catalyzed by a solid acid

A novel solid acid prepared from concentrated sulfuric, boric and phosphoric acid is a highly selective catalyst for the dimerization of α-methylstyrene at room temperature to generate 4-methyl-2,4-diphenyl-1-pentene.     

Preparation of ω-tetrahydropyran-2-ylsulfanylalkylmagnesium chlorides: Useful reagents for the synthesis of 1-(ω-mercaptoalkyl)-1,2-dihydrobuckminsterfullerenes (C60)

ω-Tetrahydropyran-2-ylsulfanylalkylmagnesium chlorides are prepared as Grignard reagents containing protected mercaptoalkyl chains, which are useful for the direct introduction of ω-mercaptoalkyl chains to electrophiles. In order to prove the usefulness of these reagents, they were reacted with buckminsterfullerene (C₆₀) to give 1-(ω-mercaptoalkyl)-1,2-dihydrobuck minsterfullerenes after the deprotection of THP group with TFA.     

Separation of salidroside from Rhodiola crenulata by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) was used to purify salidroside from an extract of Rhodiola crenulata with two steps using a two-phase solvent system composed of ethyl acetate-n-butanol-water (1:4:5, v/v) in the first run and chloroform-methanol-isopropanol-water (5:6:1:4) in the second run. The method yielded 21.9 mg of salidroside from 1.216 g of the crude sample at 98% purity determined by HPLC analyses. Identification was performed by 1H NMR, 13C NMR, and MS.     

三(2-苯并咪唑亚甲基)胺硝酸镍(Ⅱ)配合物的合成及结构

三（２－苯并咪唑亚甲基）胺简称ＮＴＢ与Ｎｉ（Ⅱ）的硝酸盐形成配合物Ｃ２８Ｈ３５Ｎ９Ｏ９Ｓ２Ｎｉ。本文报道其合成，红外光谱及晶体结构。该化合物为三斜晶系，空间Ｐ１↑－，ａ＝９．６５０（３），ｂ＝１２．７１６（２），ｃ＝１４．４３６Ａ，α＝１１．４６（２），β＝９１．６６（３），γ＝９７．５５（２）°，Ｖ＝１７１８（２）Ａ＾３，Ｚ＝２，Ｆ（０００）＝７９３，Ｄｃ＝１．４８ｇ／ｃｍ＾３，Ｍｒ＝７６４．１     

Single Atom Alloy Preparation and Applications in Heterogeneous Catalysis

There have been remarkable progresses in manipulating heterogeneous catalysts' nanostructures in the past decade. The concept of single atom alloy (SAA) was firstly proposed in 2012 when researchers successfully stabilized single Pd atoms on the Cu(111) surface. However, earlier work in 2009, which focused on replacing one Au atom with a Pd atom in thiolate protected Au₂₅ nanoclusters, could also be considered as the pioneer work of single atom alloy. Both kinds of single atom alloys exhibited the potential of maximum utilization of scarce elements and attractive catalytic performances. The well‐defined structures of SAA catalysts make accurate modeling possible, which further realizes the rational design of single atom alloy catalysts. In this review, we summarize the research trajectory of single atom alloys as well as recent achievements in this field. We also introduce several commonly adopted characterization methods for SAA catalysts such as scanning tunneling microscopy (STM), temperature programmed reaction (TPR), extended X‐ray absorption fine structure (EXAFS) spectra, matrix assisted laser desorption/ionization mass spectrum (MALDI‐MS) and differential pulse voltammetry (DPV). Through discussing recent progresses in SAA catalysts, we propose that future researches in this filed should be focused on exploring new kinds of metal nanocrystals and controlling the nanostructure of SAA even more precisely.     

低温原子化石墨炉原子吸收法测定环境和生物样中的镉

本文描述了以氩/氢混合气体作保护气体,测定环境和生物样品中痕量镉的石墨炉原子吸收法。实验证明,与纯氩气作保护气体相比较用氩/氢混合气体作保护气体,能够降低镉的原子化温度(100℃),并且减少基体物质如MgCl_2和NaClO_4的干扰。这种改善氯化物和高氯酸盐基体干扰的机理,主要是由于氢的存在与基体中的氯形成高离解能的氯化氢,从而避免了通常在镉原子化之前形成易挥发的氯化镉而损失。用本方法测定了七种标准参考物质,结果与标准值一致,证明方法是可靠的。     

Density functional study of the l-proline-catalyzed α-aminoxylation of aldehydes reaction: The reaction mechanism and selectivity

The reaction mechanism of the l-proline-catalyzed α-aminoxylation reaction between aldehyde and nitrosobenzene has been investigated using density functional theory (DFT) calculation. Our calculation results reveal following conclusions [1]. The first step that corresponds to the formation of C–O bond, is the stereocontrolling and rate-determining step [2]. Among four reaction channels, the syn-attack reaction channel is more favorable than that of the anti one, and the TS-ss channel dominates among the four channels for this reaction in the step of C–O bond formation [3]. The intermolecular hydrogen bond between the acidic hydrogen of l-proline and the N atom of the nitrosobenzene in an early stage of the process catalyzes very effectively the C–O bond formation by a large stabilization of the negative charge that is developing at the O atom along the electrophilic attack [4]. The effect of solvent decreases the activation energy, and also, the calculated energy barriers are decrease with the enhancement of dielectric constants for C–O bond formation step. These results are in good agreement with experiment, and allow us to explain the origin of the catalysis and stereoselectivity for l-proline-catalyzed α-aminoxylation of aldehyde reaction. The addition of H₂O to substituted imine proline, intermolecular proton-transfer steps, and the l-proline elimination process were also studied in this paper.