TBAI-mediated regioselective sulfenylation of indoles with sulfonyl chlorides in one pot

A versatile method for the synthesis of 3-sulfenylated indoles via TBAI promoted sulfenylation of indoles with sulfonyl chlorides in one pot has been presented. This system features highly regioselective, metal-free, easy operation, and shows a broad functional group tolerance leading to excellent yields. And this reaction could be easily conducted in 10?mmol scale with high effectivity. A plausible mechanism is proposed.     

Electrophilicity of α-oxo gold carbene intermediates: halogen abstractions from halogenated solvents leading to the formation of chloro/bromomethyl ketones

α-Oxo gold carbenes generated via intermolecular oxidation of terminal alkynes are shown to be highly electrophilic and can effectively abstract halogen from halogenated solvents such as 1,2-dichloroethane or 1,2-dibromoethane. Chloro/bromomethyl ketones are prepared in moderate efficiencies in one step using Ph(3)PAuNTf(2) as the catalyst and 8-methylquinoline N-oxide as the oxidant.     

Electro-selective interconversion of living cationic and radical polymerizations

Orchestrating conflicting polymerization mechanisms in a single polymerization process through one external stimulus is a prerequisite to achieve in-situ selective synthesis of different monomers. Here we report an electrochemically controlled mechanism transformation that enables selective activation of living cationic or radical polymerization via an alternating voltage and dual electrocatalysts. Using identical mixed-monomer condition, a variety of desired block copolymer structures, including diblock, multiblock, random, and tapered copolymers can be obtained by simply varying the periods or phases of the alternating potential. Moreover, merging this electro-interconverted polymerization with a flow-chemistry technique can streamline preparation of functional polymer materials with complex multiblock structure. This study would offer a new vision on large-scale electrochemical synthesis of sequence-defined polymers.     

非光滑约束问题的既约次梯度法

１引言 对带约束的不可微的非线性规划问题,由于不能使用梯度,求极小点就比较困难．本文给出解决此问题的一种有效的算法． ２　非光滑约束问题的既约次梯度法 １）非线性规划问题的Ｌａｅｒａｎｅ对偶理论 考虑下面非线性规划问题其中ｇ（ｘ）＝（ｇ１（ｘ）,…,ｇｒ（ｘ））Ｔ,ｈ（ｘ））＝（ｈ１（ｘ）,…,ｈｍ（ｘ））Ｔ,ｆ（ｘ）＝　　　　　　Ｒｎ中是Ｌｉｓｐｓｃｈｉｔｚ连续的ｉ＝１,２,…,ｒ,ｊ＝１,２,…,ｍ相应的Ｌａｇｒａｎｇｅ对偶问题为其中　　（ｕ,　）＝ｉｎｆＬ（ｘ;ｕ,ｖ）＝ｉｎｆ（ｆ（ｘ）＋ｕＴ…     

用电解法采集钢样和测定不锈钢中固溶钛

用由阴离子交换膜隔开的三室电解池作为采样器,电解法采集１Ｃｒ１８Ｎｉ９Ｔｉ不锈钢样品,并测定其中固溶钛的含量。测定结果和酸溶样法的一致。文中讨论了采样原理、采集质量的确定方法,电解质及电解电流的选择。     

~（211）At标记抗胃癌单抗3H11的高效液相色谱分析

报道了~（２１１）Ａｔ标记抗胃癌单抗３Ｈ１１的高效液相色谱分析方法。采用疏水性色谱柱和梯度洗脱程序,３Ｈ１１紫外色谱峰的保留时间（ｔ＿Ｒ）为１３．００ｍｉｎ,与此相对应出现~（２１１）Ａｔ－３Ｈ１１的放射性色谱峰,并与其它放射性杂质峰有较好的分离。在０．３５～３．５μｇ范围内,３Ｈ１１色谱峰的峰面积与进样量呈线性关系。     

钻穿与屏蔽效应的从头计算研究

Slater等根据原子结构的量子理论提出用屏蔽常数σ_i表示某自旋轨道i上的电子(简称i电子)所受其它各电子的排斥作用相当于抵消掉若干个核电荷的吸引作用,并通过对各元素的X-射线和光学光谱项的理论分析确定了j-电子对i-电子的屏蔽常数σ_(ji)的一些规律。徐光宪等曾对其加以改进。应用这些规律可判断多电子原子价轨道能级次序,并成功地从理论上阐明由实验确定的电子分层排布规律,使元素周期律从理论上得到发展。“屏蔽”效应主要是表达电子相互排斥的效应。把传统的“钻穿”效应的概念略加改进后,可使其主要表达核对电子吸引作用的效应。为此,定义i-电子轨道半径参量r_(p,i)的概念,     

Flow-injection catalytic kinetic determination of manganese using stopped-flow and gradient calibration

Based on the principle of Mn(II) catalysis of the Tiron-hydrogen peroxide reaction, a catalytic kinetic spectrophotometric determination of traces of manganese (ca. 10^?7 M) by flow injection was established. In combination with a microcomputer, by using gradient dilution and the stopped-flow method, onlya single standard solution was needed for calibration. The method has a high selectivity and a sampling rate of 40 h^?1. Traces of manganese in natural water were determined with a maximum relative standard deviation of 5.5% (n = 6).