催化量的氧化钙-硅胶对Sharpless烯丙醇不对称环氧化的影响

当在Sharpless试剂中加入催化量的金属氢化物和硅胶后, 烯丙醇的不对称环氧化反应时间大为缩短, 而化学和光学产率不受影响。着重讨论了氢化钙和硅胶对Sharpless烯丙醇不对称环氧化的作用。     

CH_2CH(~2A')自由基与臭氧反应机理的理论研究

用量子化学MP2（full）方法,在6－311+ +G~(**)基组水平上研究了CH_2CH (~2A~＇)自由基与臭氧反应的机理,全参数优化了反应过程中反应物、中间体、过 渡态和产物的几何构型,在QCISD（T,full）/6-311+ +G~(**)水平上计算了它们的 能量,并对它们进行了振动分析,以确定中间体和过渡态的真实性,研究结果表明 ：CH_2CH(~2A~＇)自由基与臭氧反应有两条可行的反应通道,分别为：CH_2CH (~2A~＇)+O_3→TS1→M1→TS2→O_2+OCH_2CH→TS4+O_2→O_2(~3∑_g)+CH_2CHO (~2A~＂)和CH_2CH(~2A~＇)+O_3→M2→TS3→O_2(~3∑_g)+CHO(~2A~＂),后一个反 应通道较容易发生,而且反应活化能小（2.97kJ/mol）,说明CH_2CH(~2A~＇)自由 基与臭氧之间的反应活性很强。     

NARROW-DISPERSED CROSSLINKED CORE-SHELL POLYMER MICROSPHERES PREPARED BY SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION＊

Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) microspheres were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as stabilizer. The surfaces of PDVB microspheres were chloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzene initiating core sites for subsequent ATRP grafting of styrene using CuCl/bpy as catalytic system. Polystyrene was found to be grafted not only from the particle surfaces but also from within a thin shell layer, resulting in the formation of particles size increased from 2.38-2.58μm, which can further grow to 2.93μm during secondary grafting polymerization of styrene. This demonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature. All of the prepared microspheres have narrow particle size distribution with coefficient of variation around 10%.     

丙三醇在Pt电极上吸附和氧化过程的原位FTIR反射光谱研究

运用电化学循环伏安(CV)和原位FTIR反射光谱方法, 研究了丙三醇在Pt电极上的氧化过程。结果指出, 丙三醇的氧化是一个复杂的表面过程。其间包括脱水、吸附、解离等步骤。根据CV和红外实验数据, 本文提出了Pt电极上丙三醇解离吸附的表面反应机理和不同电位下丙三醇氧化的分子过程。     

Pulse-radiolysis studies on 4-pyridinemethanol and 4-pyridinecarboxaldehyde in aqueous solutions: dimer radical anion formation in the case of 4-pyridinecarboxaldehyde

Reactions of e _aq ^– , H atom and OH radicals with 4-pyridinemethanol (4-PM) and 4-pyridinecarboxaldehyde (4-PCA) have been studied at various pH values using the pulse radiolysis technique. Reaction of e _aq ^– with 4-PM and 4-PCA leads to the formation of pyridinyl and ketyl radicals of 4-PM and 4-PCA, respectively. Ketyl radicals formed from 4-PCA react with the parent molecule to give a dimeric radical species. At pH 7, the equilibrium constant for the dimer formation was determined to be 13 500 M^-1. At pH 13 also dimer radical formation was observed. Reaction of e _aq ^– with 4-PM was found to give highly reducing pyridinyl radicals. Reaction of OH radicals with 4-PM gives a mixture of species,viz., OH adducts and radicals formed by H-atom abstraction from the –CH₂OH moiety. Radicals formed by H-atom abstraction reaction from 4-PM were found to be reducing in nature. O^– radicals were found to react with 4-PM exclusively by H-abstraction pathway.     

示差脉冲极谱研究 VI.胞嘧啶在滴汞电极上的极谱电流

本文对胞嘧啶在滴汞电极上的示差脉冲极谱波的性质进行了研究,探讨了电极反应过程,推导了相应的脉冲极谱电流方程式,理论与实验结果完全相符。     

CBS法合成光学活性二茂铁基醇

以非天然氨基酸合成的手性β-氨基醇(4a～4c)为催化剂，用于不对称硼烷还原反应来合成光学活性的二茂铁基醇(1a～1e)，对映体过量值高达96%。     

第十五华沙国际金属有机化学讨论会

本文从(一)金属有机化合物的合成、结构及反应性的研究、(二)新颖、独特和官能化配体的研究、(三)金属原子簇合物化学、(四)催化、(五)有机硅化学、(六)其他研究领域等六个方面做了阐述。本届讨论会较全面地体现了从上届会议以来国际金属有机化学的研究进展及发展趋势。这届会议的成功举行,不仅强化了各国金属有机化学家间的学术交流而且增进了各国人民之间的友好情谊。     

氯离子存在下四苯基卟啉合锰的电化学和现场光谱电化学 I: 还原过程

在二氯乙烷溶液中,研究了氯离子存在下四苯基卟啉合锰,(TPP)Mn(III)ClO~4,各步电极氧化还原的过程机理,证明了Mn(II),Mn(III)中心都只有一个Cl^-配位,其结果使锰卟啉中心金属Mn(III)/Mn(II)的半波电位负和多约100mV,测定了Cl^-与Mn(III)中心的配位反应的平衡常数为2.2×10^4.     

ESR方法检测竹红菌素的半醌负离子自由基

从顺磁共振波谱检测到通过竹红菌素的光诱导还原和基态竹红菌素跟脂肪胺的电子转移两条途径所得到的自由基信号, 并由电化学还原得到同一自由基, 确认它为半醌负离子自由基。竹红菌素溶液中加入芳香胺观察不到ESR信号。它的3,10位上与醌基相邻近的羟基离解以后, 无论在基态还是在激发态都观察不到ESR信号。此外, 还从吸收光谱观察到半醌负离子自由基吸收以及竹红菌素跟脂肪胺之间的相互作用。