Novel Phenomenon of Oxygen-to-oxygen Silyl Migration in Directed Aldol Reaction

The phenomenon of migration of the silyl groups from α-oxygen to β-oxygen in sodium aldol reaction was observed for the first time in this paper.     

中药一枝黄花、黄连、天麻、蛇床子中8种微量元素的测定

采用原子吸收光谱仪对一枝黄花、黄连、天麻、蛇床子中Fe、Ca、Mg、Mn、Cr、Cu、Zn、Pb八种无机元素的含量进行了测定,为进一步研究其药理和用途提供基础。     

Speciation analysis of inorganic arsenic by microchip capillary electrophoresis coupled with hydride generation atomic fluorescence spectrometry

A novel method for speciation analysis of inorganic arsenic was developed by on-line hyphenating microchip capillary electrophoresis (chip-CE) with hydride generation atomic fluorescence spectrometry (HG-AFS). Baseline separation of As(III) and As(V) was achieved within 54 s by the chip-CE in a 90 mm long channel at 2500 V using a mixture of 25 mmol l(-1) H3BO3 and 0.4 mmol l(-1) CTAB (pH 8.9) as electrolyte buffer. The precisions (RSD, n=5) ranged from 1.9 to 1.4% for migration time, 2.1 to 2.7% for peak area, and 1.8 to 2.3% for peak height for the two arsenic species at 3.0 mg l(-1) (as As) level. The detection limits (3sigma) for As(III) and As(V) based on peak height measurement were 76 and 112 microg l(-1) (as As), respectively. The recoveries of the spikes (1 mg l(-1) (as As) of As(III) and As(V)) in four locally collected water samples ranged from 93.7 to 106%.     

电解质水溶液在丙酸十二铵-四氯化碳溶液中的增溶

表面活性剂在非极性溶剂中形成的反胶束在催化反应、光化学、蛋白质苹取分离等方面有着广泛的应用问．这些应用与反胶束的性质有着密切的关系，而增溶水后的反胶束其形状和大小都会发生很大的变化．增溶不同水量的反胶束的微极性、酸碱性、微勤度等已有不少文献报导［2－5］．一些不溶于非极性溶剂而溶于水的物质可以溶解在非极性溶剂中的反胶束核心水团中，这个现象被称为二次增溶．其中，电解质的二次增溶对于研究配体转换反应。酶催化反应问及改变反胶束内部的微环境有着十分重要的作用，Aebi和Weibush回首先研究了有水存在时N。CI在A…     

氟阴离子在有机合成中的应用：Ⅱ.无水氟化钾催化乙酐与苯甲醛的Perkin反应

用无水醋酸盐催化苯甲醛与乙酐的Perkin反应,一般反应时间较长,产率最高为55—60％.用三乙胺、吡啶和无水碳酸钾等作催化剂,产率也无明显提高.近年来氟阴离子在有机合成中的应用迅速发展,我们曾用无水氟化钾催化成功地实施了丙二酸二乙酯与苯甲醛的Knoevenagel缩合,并研讨了该反应的微环境效应.本工作首次用无水氟     

FT-IR evidence for the participation of protonic sites in the heterolytic cleavage of C?H bonds of methane over HZSM-5 zeolite

It has been observed by FT-IR spectroscopy that both kinds of Brönsted acid protons present in HZSM-5 zeolite may be involved in the adsorption of methane at low temperature (173 K) and exchange with CH₄ or CD₄ at high temperature (>500°C). The sites which can adsorb methane at low temperature are the active sites for methane conversion at high temperature. Over HZSM-5 zeolite, the activation of methane is suggested to occur via a heterolytic cleavage of C–H bond with the assistance of protons.     

茶碱抗体的制备及鉴定

茶碱在临床上是一种非常有用的药剂。本文报道一种新的茶碱抗血清的制各及鉴定方法．用混合酸酐法合成抗原，借助于紫外光谱对其进行定性和定量分析。用混合免疫法免疫兔子，用免疫扩散法对抗血清进行鉴定。     

三环[5,2,1,0~(2,6)]癸-3-烯-8,9-二羧酸二甲酯的合成

通过对双环戊二烯的选择性羰基化加成，高产率地合成了三环[5、2、1、02，6]癸-3烯-8，9-二羧酸二甲酯。得到了无色透明的片状晶体，产率为90％。