钯催化的交叉偶联反应——2010年诺贝尔化学奖获奖工作介绍

钯催化的交叉偶联反应是非常实用的合成新方法.文章给出了Heck反应、Negishi反应和Suzuki反应的概念,对其反应机理作了详细的说明,并对其在复杂化合物和天然产物全合成中的应用作了评价.     

水相金属有机化学

本文对近年来锡、锌、铋等介入下的水相金属有机化学作了综述。特别对水相Barbier 反应作了较详细的介绍, 同时也描述了一些典型的水相金属有机反应,如Immonium 阳离子的烷基化反应, α, β 不饱和化合物的共轭加成, 醇醛缩合反应及水溶性金属有机化合物的反应等。某些反应的机理也被讨论。     

乙酸正丁酯合成实验的改进

对乙酸正丁酯的制备方法进行了改进。用甲基磺酸钙作催化剂,环己烷作共沸溶剂,在回流分水条件下进行反应。对正丁醇、乙酸、环己烷和催化剂的用量进行了优化,得出较佳反应条件,在该反应条件下,酯化率可达93%。反应结束后,催化剂经简单的相分离就可重复使用。     

有机金属钼催化下的甲基萘氧化反应

本文研究了在液相条件下用有机金属钼作均相催化剂,叔丁基过氧化氢作氧化剂,把甲基萘氧化成甲基萘醌的反应。讨论了溶剂、催化剂、反应温度、氧化剂与甲基萘的配比以及萘环上不同取代基对反应的影响,     

2-取代-4(5)-烷氧基咪唑的合成

我们曾报道了N-氰甲基苯甲亚氨酸乙酯(1a)的烷基化反应、Micheal加成和与芳醛的缩合反应。本文报道碱催化下N-氰甲基亚氨酸乙酯在醇中的成环反应结果。在固-液相转移催化条件下,N-氰甲基苯甲亚氨酸乙酯(1 a)与丙烯酸甲酯反应,生成Micheal加成产物。当用乙醇钠作碱、乙醇作溶剂时,1a与丙烯酸甲酯反应没有生成Micheal     

溶剂极性经验参数在推断有机反应历程中的作用

多数化学反应都是在一定的溶剂中进行的,而溶剂对反应有不可忽视的影响.例如在碱性条件下,醛、酮被还原成相应的烃的反应:以乙醇作溶剂需要密封、长时间的加热进行反应;以二缩或三缩乙二醇作溶剂在常压下短时间加热就达到目的,而且得率较高;用二甲亚砜作溶剂在常温常压下就可以顺利地进行反应.这些现象说明了溶剂对反应的重要性. 溶质与溶剂分子间的相互作用称为溶剂效应.按照溶质与溶剂分子间相互作用力性质的不同,将溶剂效     

磷钼钒杂多酸催化苯制苯酚的研究

将磷钼钒杂多酸应用于以过氧化氢作氧化剂,冰醋酸作溶剂的苯一步氧化制苯酚反应中,分别考察了杂多酸、过氧化氢和冰醋酸的用量,以及反应温度和反应时间等因素对苯制苯酚反应的影响,并通过单因素实验方法确定了较为适宜的工艺条件.     

6-氯-8-烃基-9-芳基嘌呤类衍生物的合成

以4,6-二氯-5-氨基嘧啶为原料,经N-烃基化反应、缩合反应和氯化反应,合成了一系列未见文献报道的6-氯-8-烃基-9-芳基嘌呤衍生物,所有化合物均通过1H NMR、MS和元素分析确定其结构。 研究结果表明,N-烃基化反应时,芳胺使用盐酸作催化剂,芳基脂肪胺用有机碱三乙胺作催化剂,缩合反应时,多聚磷酸(PPA)用量过多会影响传质效果,影响反应的收率。 讨论了微波反应方式对氯化反应的影响。     

Sonogashira反应研究的最新进展

对Sonogashira反应的最新研究进展作了综述. 详细地介绍了Sonogashira 反应的最新优化、联串化、绿色化以及非Pd催化的Sonogashira反应等, 同时还综述了Sonogashira反应的机理研究.     

镁铝原电池数字化实验的意外——再探铝与碱性溶液的反应

用电压传感器测得使用铝、镁作电极,氢氧化钠溶液或氨水作电解质的原电池,在放电过程中存在电极极性翻转现象,说明铝片不仅能与强碱反应,也能与氨水反应。该结论和铝片和氨水反应的试管实验的结果一致。换用碳酸钠溶液作电解质的原电池不存在电极极性翻转现象;结合试管实验中铝片与碳酸钠溶液反应的产物分析,发现有难溶于水的碱式碳酸钠铝生成,推测其覆盖在铝片表面,避免了电极极性翻转。     

Theoretical study of electronic structure of rhodium mononitride and interpretation of experimental spectra

Potential energy curves of 22 electronic states of RhN have been calculated by the complete active space second‐order perturbation theory method. The X¹Σ₀⁺ is assigned as the ground state, and the first excited state a³Π₀+ is 978 cm^?1 higher. The ¹Δ(I) and B¹Σ⁺ states are located at 9521 and 13,046 cm^?1 above the ground state, respectively. The B¹Σ⁺ state should be the excited state located 12,300 cm^?1 above the ground state in the experimental study. Moreover, two excited states, C¹Π and b³Σ⁺, are found 14,963 and 15,082 cm^?1 above the X¹Σ⁺ state, respectively. The transition C¹Π₁–X¹Σ₀⁺ may contribute to the experimentally observed bands headed at 15,071 cm^?1. There are two excited states, D¹Δ and E¹Σ⁺, situate at 20,715 and 23,145 cm^?1 above the X¹Σ⁺ state. The visible bands near 20,000 cm^?1 could be generated by the electronic transitions D¹Δ₂–a³Π₁ and E¹Σ⁺₀–X¹Σ⁺₀ because of the spin–orbit coupling effect. © 2013 Wiley Periodicals, Inc.     

Exploration of the potential application of plutonium isotopes in source identification of sandstorm in the atmosphere of Beijing

Plutonium (Pu) is an anthropogenic radionuclide which mainly derived from atmospheric nuclear tests in the environment. In this study, the Pu isotopes (²³⁹Pu and ²⁴⁰Pu) in aerosol samples collected during the sandstorm and non-sandstorm period were measured by accelerator mass spectrometry (AMS) and the behavior of Pu was studied. The activity concentrations of ²³⁹Pu and ²⁴⁰Pu in the aerosol samples of Beijing were ranged from 0.62 nBq/m³ to 99.6 nBq/m³ for ²³⁹Pu and 3.51 nBq/m³ to 60.23 nBq/m³ for ²⁴⁰Pu, respectively. ²³⁹Pu and ²⁴⁰Pu concentrations exhibited a remarkable seasonal variation trend, with the higher results showed in spring, and the relatively lower concentrations in winter. The observed higher concentration of ²³⁹Pu and ²⁴⁰Pu detected in sandstorm samples further indicated Pu was closely related to the occurrence of sandstorms. The global fallout characteristics of ²⁴⁰Pu/²³⁹Pu atom ratios (average 0.20, ranging from 0.16 to 0.27) in aerosol samples indicating that global fallout was the major source of Pu in the atmosphere. Using aluminum (Al) as an indicator of soil resuspension, significant positive correlation between ²³⁹Pu and Al (r² = 0.934), ²⁴⁰Pu and Al (r² = 0.525) revealed that soil resuspension was a primary source of atmospheric Pu in Beijing. These results implied that the combination of ²³⁹Pu, ²⁴⁰Pu and Al could be used as the potential tracer of sandstorm.     

Radiochemical characterization of spring waters in Balaton Upland, Hungary, estimation of radiation dose to members of public

Hungary is rich in spring waters. A survey studying the naturally occurring alpha emitter radionuclides in 30 frequently visited and regularly consumed spring waters was conducted out in the Balaton Upland region of Hungary.²²⁶Ra, ²²⁴Ra, ²³⁴U, ²³⁸U and ²¹⁰Po activity concentrations were determined by using alpha spectrometry after separation from matrix elements. Average concentration (mBq L^{− 1}) of ²²⁶Ra, ²²⁴Ra, ²³⁴U, ²³⁸U and ²¹⁰Po in the spring waters is varied from 2.1 to 601, from < 1.1 to 65.4, from 3.9 to 741.9, from < 0.44 to 274.3 and from 2 to 15.2 respectively. In most cases radioactive disequilibrium was observed between uranium and radium isotopes. The doses for the analyzed samples of spring water are in the range 3.59–166.73 μSv y^{− 1} with an average 18.2 μSv y^{− 1} .This is well below the 100 μSv y^{− 1} reference level of the committed effective dose recommended by WHO. Only one water sample had a dose higher than 100 μSv y^{− 1}, mainly due to the contribution from radium (²²⁶Ra, ²²⁴Ra) and ²¹⁰Po isotopes. This study provides important information for consumers and authorities about their internal radiological exposure risk from spring water intake.     

New developments in the production of theranostic pairs of radionuclides

A brief historical background of the development of the theranostic approach in nuclear medicine is given and seven theranostic pairs of radionuclides, namely ^44gSc/⁴⁷Sc, ⁶⁴Cu/⁶⁷Cu, ⁸³Sr/⁸⁹Sr, ⁸⁶Y/⁹⁰Y, ¹²⁴I/¹³¹I, ¹⁵²Tb/¹⁶¹Tb and ¹⁵²Tb/¹⁴⁹Tb, are considered. The first six pairs consist of a positron and a β^?-emitter whereas the seventh pair consists of a positron and an α-particle emitter. The decay properties of all those radionuclides are briefly mentioned and their production methodologies are discussed. The positron emitters ⁶⁴Cu, ⁸⁶Y and ¹²⁴I are commonly produced in sufficient quantities via the (p,n) reaction on the respective highly enriched target isotope. A clinical scale production of the positron emitter ^44gSc has been achieved via the generator route as well as via the (p,n) reaction, but further development work is necessary. The positron emitters ⁸³Sr and ¹⁵²Tb are under development. Among the therapeutic radionuclides, ⁸⁹Sr, ⁹⁰Y and ¹³¹I are commercially available and ¹⁶¹Tb can also be produced in sufficient quantity at a nuclear reactor. Great efforts are presently underway to produce ⁴⁷Sc and ⁶⁷Cu via neutron, photon and charged particle induced reactions. The radionuclide ¹⁴⁹Tb is unique because it is an α-particle emitter. The present method of production of ¹⁵²Tb and ¹⁴⁹Tb involves the use of the spallation process in combination with an on-line mass separator. The role of some emerging irradiation facilities in the production of special radionuclides is discussed.     

The determination and application of 87Sr/86Sr ratio in verifying geographical origin of wheat

As ⁸⁷Sr/⁸⁶Sr ratio plays a significant role in authenticating the geographical origin of foodstuff, it is important to identify where the ⁸⁷Sr/⁸⁶Sr signature in food comes from, and the methods of ⁸⁷Sr/⁸⁶Sr ratio analysis in food and environmental samples. Wheat with three genotypes, soil and groundwater samples were collected from three regions of China during harvest time of 2014. The ⁸⁷Sr/⁸⁶Sr ratios in the samples were determined by thermal ionization mass spectrometer in order to investigate the possible source of ⁸⁷Sr/⁸⁶Sr in wheat, and the concentrations of Rb and Sr in wheat and soils were also detected by inductively coupled plasma mass spectrometry and combined with ⁸⁷Sr/⁸⁶Sr ratio in order to trace the geographical origin of wheat. The ⁸⁷Sr/⁸⁶Sr ratio, the contents Rb and Sr, and Rb/Sr ratio of wheat and soil samples showed significant differences among three regions. The ⁸⁷Sr/⁸⁶Sr ratios and the concentrations of Rb and Sr in soils were higher than those in corresponding wheat. The ⁸⁷Sr/⁸⁶Sr ratio in wheat was identical to that corresponding soil NH₄NO₃ extracts (labile fraction of soil) and groundwater. Wheat uptake more Rb than Sr. 3D distribution of ⁸⁷Sr/⁸⁶Sr, Rb and Sr could identify wheat samples from different regions clearly. The ⁸⁷Sr/⁸⁶Sr ratio of wheat reflects the ⁸⁷Sr/⁸⁶Sr ratio of the associated environment including soil and groundwater. It is expected that the use the parameters of ⁸⁷Sr/⁸⁶Sr ratio, the contents of Rb and Sr will allow to trace geographical origin of wheat. Copyright © 2017 John Wiley & Sons, Ltd.     

A NMR method for the analysis of mixtures of alkanes with different deuterium substitutions

¹³C NMR at 125.76 MHz with ¹H and ²H decoupling, ²H NMR at 76.77 MHz with ¹H decoupling, and ¹H NMR at 500.14 MHz with ²H decoupling were employed as analytical tools to study the complex mixtures of deuterated ethanes resulting from the catalytic H–D exchange of normal ethane with gas-phase deuterium in the presence of a platinum foil. Reference samples consisting of 1:1 binary mixtures of pure normal ethane and ethane-d_n (n=1–6) were used to identify the peak positions in the ¹³C, ²H, and ¹H NMR spectra due to each individual isotopomer, and the effect of isotopic substitution on the chemical shifts was determined in each case. While the NMR of all three nuclei worked well for the identification of the individual components of the 1:1 standard mixtures, both ¹H and ²H NMR suffered from inadequate resolution when studying complex reaction mixtures because of the broadening of the lines due to ¹H–¹H (¹H NMR) and ²H–²H (²H NMR) couplings. ¹³C NMR was therefore determined to be the method of choice for the quantitative analysis of the reaction mixtures. Using the ¹³C NMR results, a correlation that takes into account the primary and secondary isotope substitution effects on chemical shifts was deduced. This equation was used for the identification of the individual components of the mixtures, and integration of the individual observed resonances was then employed for quantification of their composition. This study shows that ¹³C NMR with ¹H and ²H decoupling is a viable procedure for studying mixtures of deuterated ethanes. Furthermore, the additivity of the isotopic effects on chemical shifts and the transferability of the values obtained with ethane to other molecules makes this approach general for the analysis of other isotopomer mixtures.     

Ab initio calculations of nuclear quadrupole coupling constants of low-lying rovibrational levels in the X1Σ+ and a1Σ+ states of all isotopic species of LiH

The ²H, ⁶Li, and ⁷Li quadrupole coupling constants of the low-lying rovibrational levels in the X¹∑⁺ and A¹∑⁺ electronic states of ⁷Li²H, ⁶Li²H, ⁷Li¹H, and ⁶Li¹H are calculated from molecular wave functions which explicitly describe nuclear motion. Except for the lithium coupling constants in the A¹∑⁺ state, the vibrational dependence of the nuclear quadrupole coupling is found to be significant for all the studied isotopic species. On the other hand, the rotational dependence appears to be important only for the deuteron coupling constant of ⁷Li²H and ⁶Li²H in the A¹∑⁺ state. Special attention is paid to relative magnitudes of the Li and D quadrupole coupling constants in the ⁷Li²H and ⁶Li²H isotopic species. The information about the relative magnitudes and their changes with vibrational excitation is used to outline a theoretical approach to the interpretation of the hyperfine structure of the spectra of these species.     

Estimation of a priori errors in ab initio calculations of thermochemical values for the example of the dissociation energies of the ZnO and ZnS molecules

The total energies of ZnO(¹Σ), ZnO(³Π), ZnO^?(²Σ), ZnO⁺(²Σ), ZnS(¹Σ), ZnS(³Π), ZnS^?(²Σ), and ZnS⁺(²Σ) were calculated ab initio by the CCSD(T) method with the use of atomic basis sets including 80, 84, and 93 functions for O, S, and Zn, respectively. Similar calculations were performed for the Zn atom [Zn(¹ S), Zn(³ P), Zn⁺(² S), Zn²⁺(¹ S)] and several oxygen and sulfur states [O(³ P), O^?(² S), O(¹ D), O₂(³Σ), O ₂ ^? (²Π), O₂(¹Δ), S(³ P), S^?(² S), S(¹ D), S₂(³Σ), S ₂ ^? (²Π), and S₂(¹Δ)]. The ideology of engagement groups suggested by us is considered. According to this approach, data treatment can be performed on the assumption that the errors in all the 24 results obey the normal distribution law. As a result, we obtained D _e(ZnO) = 1.70 ± 0.21 and D _e(ZnS) = 1.57 ± 0.25 eV (at a 95% confidence level).     

Influence of transition metal ions on the textural properties of alumina and aluminasilicates

Accelerated phase transformations and chemical reactions of metastable aluminas and kaolinite, doped with Cu^{2 +}, Mn^{3 +}/Mn^{2 +} and Fe^{3 +}/Fe^{2 +} ions, are accompanied with accelerated decrease of surface area and pore volume values. The phenomena in metal ion doped samples are explained by a catalytic mechanism, in terms of the Jahn-Teller effect. This revised version was published online in June 2006 with corrections to the Cover Date.