3d过渡晶体化学键共价性和光谱位移研究

本文利用ＰＶ理论通过考虑３ｄ电子对晶体化学键的影响,计算了若干３ｄ过渡金属化合物的化学键参数并运用于Ｒａｃａｈ参数和穆斯堡尔谱同质异能位移的研究,计算得到的结果与实验值符合的很好。     

室温离子液体中乙酸钠和氯苄催化合成乙酸苄酯

在多种1,3-二烷基咪唑和烷基吡啶室温离子液体中考察了较温和条件下乙酸 钠和氯化苄作用合成乙酸苄酯反应。在反应温度下（60 ℃）,熔融的三水合乙酸 钠与离子液体相混溶,氯苄同乙酸钠作用得到乙苄酯,它与四氟硼酸1-乙基-3-甲 基咪唑离子液体不溶而分层。反应结束后产物乙酸苄酯可直接倾析得到,乙酸苄酯 产率达到90%,纯度超过99%。此离子液体催化体系简化了产物分离,离子液体可以 重复使用。     

AC Electrochemical Copper and Aluminum Oxidation in Sodium Acetate Solutions

Electrochemical copper and aluminum oxidation using alternating current of industrial frequency was carried out in an aqueous sodium acetate solution. Simultaneous oxidation of metals accelerates copper oxidation, but does not significantly influence the aluminium oxidation rate. It results in the preparation of the copper-aluminum oxide system with a high content of copper oxide (up to 70 wt %). High energy consumption due to the voltage loss to overcome the resistance of the oxidation product layer on the electrode surface considerably limits the process and its product application. Furthermore, the chemical aluminum oxidation in alkaline medium of an aqueous sodium acetate solution instead of electrochemical one does not result in the power-saturated, nanosized metal oxide formation. The results obtained do not only underline the new technology of nanomaterial production, but also allow scientists to consider the mechanisms of the metal oxidation AC-process.     

硫酸氢钠催化合成乙酸β-萘酯

乙酸 β-萘酯可用做评价酯酶、或模拟酯酶活性的底物 [1,2 ] ,此类化合物可用乙酰氯在胺的作用下与酚反应制得 ,但用有机胺溶剂时后处理不方便 [3] .浓硫酸催化酸或酸酐与醇 (酚 )反应也可制得乙酸酯 ,但该法对设备腐蚀大 ,且反应体系为均相 ,存在催化剂和产物的分离问题 .近年来 ,人们开发了各种取代浓硫酸的催化剂 ,其中多相催化剂特别引人注目 [4 ] .本文考察了硫酸氢钠催化乙酸 β-萘酯的合成 ,发现其是有效的多相酯化催化剂 ,该法基本具备绿色化学的要求 .尚未见有文献报道 .醋酸酐、β-萘酚、Na HSO4 ·H2 O均为分析纯 .Na HSO4 …     

有机盐类化合物醋酸钠的电喷雾质谱研究

利用电喷雾质谱技术研究了有机盐类化合物醋酸钠(NaAc)的特征质谱行为,实验结果表明,在全扫描电喷雾正负离子谱中都出现了质量数相差82的质谱峰簇．这与醋酸钠的相对分子质量相一致,正负质谱峰簇分别对应于簇合物离子Na^ (NaAc)n和Ac^-(NaAc)m:簇合物离子的多级串联质谱进一步证明了簇合物离子的存在。该结果为类似结构的盐类化合物的表征提供了一种新的质谱证据。     

The Crosslinking of Ethylene-Vinyl Acetate Copolymers with Sodium Alcoholates

When reacting ethylene-vinyl acetate copolymers (EVA) with sodium alcoholates in alcohol, the alcoholysis of EVA is accompanied by crosslinking reactions. Crosslinking can be detected by the increase in torque in a plastograph. This paper reports on investigations on the mechanism of the crosslinking reaction. Both crosslinking via C?C bonds and formation of a thermally reversible network via polymer alcoholate structures can be found. If an ethylene-vinyl alcohol copolymer is obtained by complete saponification of EVA, however, only thermally reversible crosslinking can be demonstrated. This leads to the conclusion that irreversible crosslinking is established through a reaction of the acetate side chains. The reaction products of the low-molecular weight model substances, pentanol-3-acetate and sodium isopropylate in isopropanol, are analyzed by means of gas chromatography. These results suggest a partial Claisen condensation as a mechanism of the irreversible crosslinking process.     

Efficient and Convenient Method for Synthesis of Benzofuran-3-acetic Acids and Naphthafuran-acetic Acids

Herein, we report an efficient and convenient method for synthesis of benzofuran-3-acetic acids and naphthafuran-acetic acids 5a–p by the reaction of substituted-4-bromomethylcoumarins with aqueous sodium hydroxide at refluxing temperature. The obtained products are characterized by infrared, ¹H NMR, ¹³C NMR, and mass spectral data. Structures 5a and 5e are confirmed by their single x-ray diffraction studies. The advantages of this method are good yields, easy workup, and no chromatographic purifications.     

等浓度碳酸氢钠和醋酸钠2种溶液的pH大小比较

利用Excel对相同浓度的NaHCO3溶液、CH3COONa溶液中离子浓度的精确计算,得出相同浓度的2溶液中,水解程度一定是HCO3->CH3COO-,但不能仅通过水解程度大小来得出pH(NaHCO3溶液)>pH(CH3COONa溶液)的结论,2溶液的pH大小还与溶液浓度有关。     

1-萘酚的紫外共振双光子电离光谱

利用脉冲分子束技术, 在305-322 nm范围内研究了1-萘酚(1NP)的共振双光子电离(R2PI)光谱. 1NP分子存在cis和trans两种旋转异构体, 但实验中仅观测到trans异构体的电子振动跃迁光谱, 其S1←S0跃迁的(0-0)带头出现在317.90 nm(即31456 cm-1)位置. 利用光谱选律及ab initio和密度泛函(DFT)计算, 对trans异构体在S1态的振动模进行标识, 得出主要对应于对称性为a'的平面内振动模. 计算显示, cis异构体在电子基态S0的能量较trans异构体高出439 cm-1, 而第一激发能却比trans异构体的低1216 cm-1, 与之相应的实验值分别是220和274 cm-1. 计算数值与实验结果在能量变化趋势上完全一致. 共振双光子电离谱中没有观测到cis异构体的光谱信号, 其原因可归结为分子束的有效冷却效应使得处于基态的cis异构体的布居数密度相对trans异构体极低, 导致cis光谱信号太小而未能被探测到.     

Origin of Spectrum Shifts of Benzophenone–Water Clusters: DFT Study

Structures and electronic excitation energies of the benzophenone–water (Bp–H₂O) and benzophenone–methanol (Bp–CH₃OH) complexes have been investigated by means of density functional theory calculations. The CAM-B3LYP/6-311++G(d,p) and higher level calculations were carried out for the system. The calculations indicate that free Bp has a nonplanar structure with twist angle of 54.2° for two phenyl rings (referred to as ?). In the case of the Bp–H₂O system, the twist angle of the phenyl rings and structure of the Bp skeleton were hardly changed by hydration (? = 55.1° for Bp–H₂O). However, the excitation energies of Bp were drastically changed by this solvation. The time-dependent density functional calculations show that the n–π* transition (S₁ state) is blue-shifted by the solvation, whereas two π–π* transitions (S₂ and S₃) were red-shifted. The origin of the specific spectral shifts is discussed on the basis of the theoretical results.     

A New Facile Synthesis of 5-Alkyl-2-Aryl-3H-Pyrazol-3-Ones

The title compounds widely used in construction of pigments and antimaterials are most usually prepared by condensation of arylhydrazines and β-keto esters ^1,2. Although a number of 5-methyl and aryl derivatives have been obtained, other 5-alkyl-3-pyrazolones are rarely mentioned in literature ³ because of the lack of a convenient method to prepare the approperate β-keto esters used in condensation.     

Isotopic Shifts of the infrared Spectra of Cholic Acid and Sodium Cholate

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Regioselectivity in the Acid Cleavage of Bicyclo[4.1.0]Heptan-3-Ones

Acid-promoted cyclopropane cleavage reactions have been employed with great success for the generation of angular methyl groups.² Sims has shown that the regioselectivity of such reactions may be influenced by acid strength.^2d We now report a case in which steric factors appear to direct the cleavage pathway.     

顺磁共振和紫外光谱法研究SDS-PEO体系的相互作用

合成更疏水的自旋探针4 羰基 2,2,6,6 四甲基哌啶氮氧自由基 2,4 二硝基苯腙.用顺磁共振（ESR）和紫外光谱法研究了十二烷基硫酸钠（SDS） 0.5 ％(w,质量分数)聚氧乙烯（PEO）体系的分子间相互作用. ESR结果表明,此水溶液体系的微极性随SDS浓度增大而减小,并且SDS与PEO聚集体具有更加紧密的堆积结构使其结合处具有较大的微粘性, SDS与PEO间的相互作用导致PEO分子链伸展. UV表明自旋探针分子可能靠近胶束的表面存在, 2,4 二硝基苯肼基团可能位于靠近SDS的硫酸根基团,定向于SDS胶束的表面,氮氧自由基基团短距离渗透到SDS胶束的碳氢核.     

Volumetric Investigations on Interactions of Acidic/Basic Amino Acids with Sodium Acetate, Sodium Propionate and Sodium Butyrate in Aqueous Solutions

The apparent molar volumes, V _φ , of L-aspartic acid, L-glutamic acid, L-lysine monohydrate and L-arginine in water and in aqueous (0.1, 0.25, 0.5 and 1.0) mol?kg^?1 sodium acetate and sodium propionate, and (0.1, 0.25 and 0.5) mol?kg^?1 sodium butyrate solutions have been determined at 288.15, 298.15, 308.15 and 318.15 K from density measurements. The partial molar volumes at infinite dilution, V ₂ ^o , obtained from V _φ data, have been used to calculate hydration numbers and partial molar expansibilities of amino acids in water and in the presence of the studied cosolutes at different temperatures. These parameters have been discussed in terms of various interactions between the acidic/basic amino acids and organic salts in these solutions. The effect of the hydrophobic chain length of the carboxylate ions has also been discussed.     

Conductance of Dilute Sodium Acetate Solutions to 469 K and of Acetic Acid and Sodium Acetate/Acetic Acid Mixtures to 548 K and 20 MPa

In order to obtain accurate association constants for sodium acetate, a very precise flow method was used to measure the electrical conductivity of dilute aqueous solutions of sodium acetate at ambient conditions and 469 K and 20 MPa. Measurements at ambient conditions, 469 and 548 K and 20 MPa, were also made on sodium acetate/acetic acid mixtures and acetic acid. In order to determine the limiting the equivalent conductances and the association constant for sodium acetate, and dissociation constant for acetic acid, the results were fitted to two modern conductance equations (Fuoss–Hsia–Fernandez–Prini and Turq–Blum–Bernard–Kunz) with accompanying activity coefficient models (mean spherical approximation and the Debye–Hückel with the Bjerrum distance). The choice of conductance equation, activity coefficient model, assumed values for the limiting equivalent conductance for minor species, and assumed equilibrium constants for minor reactions, did not significantly change the resulting equilibrium constants. The insensitivity of the calculated equilibrium constants to these choices in conjunction with the inherent precision of the flow conductance technique leads us to believe that the present results are the most accurate sodium acetate ion-pairing constants published to date. Our results for acetic acid are in good agreement with previously published results from other laboratories.     

紫外吸收光谱法在高通量筛选中的应用

 与传统化合物的单独合成及结构性能测定相比,高通量筛选技术具有简化并缩短发现目标化合物过程的特点. 以紫外吸收光谱法为手段,利用高通量筛选技术考察了Co-Ce/HZSM-5对甲烷还原NOx反应的催化活性. 研制了专用的平行反应器,使每个反应通道的反应温度相同,气体空速相近; 建立了一种高通量初级筛选催化剂库的快速方法,初步评价了不同Co/Ce比的Co-Ce/HZSM-5催化剂样品的催化活性. 结果表明,当w(Co)=2.5%及m(Co)/m(Ce)=2时,催化剂的活性最高,其活性因数达到了0.67.