“Titration” polymerization of monovinylacetylene

A polymer consisting of a saturated carbon backbone with pendent acetylenic groups was prepared from monovinylacetylene. A titration was performed between the monomer and tertiary butyllithium, its lithiating agent. The charge transfer complex formed between the solvent THF and the tertiary butyllithium was used as an indicator of the unreacted butyllithium. Hence, a stoichiometric quantity of tertiary butyllithium was added dropwise to a solution of monovinylacetylene in THF to form lithiovinylacetylene. The addition of a slight excess of butyllithium led to the polymerization of the lithiated monomer. The obtained polymer was reprotonated and characterized. This polymerization was evaluated as a possible route to synthesize poly(vinylacetylene) with processable molecular weights, for its application as a potential carbon fiber precursor. © 1996 John Wiley & Sons, Inc.     

计算滴定分析法的分类及其进展

提出了将计算滴定分析法分为控制体积滴定法和控制电位滴定法两个大类的观点。控制体积滴定法包括线性滴定法、单点滴定法及双点滴定法;控制电位滴定法包括控制单电位滴定法和控制多电位滴定法。本文介绍了两类计算滴定分析法的基本原理、方法特点、相互联系、引起误差的原因及其最新进展。     

Use of solid electrolyte GeSe-GeI<Subscript>2</Subscript> for electrochemical doping with germanium

Lead tellurite is study to show that solid electrolyte GeSe-GeI₂, which has the optimum composition and contains 5 mol % of GeI₂, can in principle be used for electrochemical doping of semiconducting materials with germanium by the coulometric titration method. Some parameters of the coulometric titration are considered. The doping efficiency is monitored by determining variations in the concentration of charge carriers using the Hall method and by measuring the EMF of corresponding galvanic cells.     

示波电位滴定法测定僵蚕中草酸铵

以高锰酸钾为滴定剂，用示波器指示终点，提出了在酸性介质中直接测定僵蚕中活性草酸铵的示范波电位滴定方法，该法灵敏度高（可指示８×１０＾－７ｍｏｌ．Ｌ＾－１ＫＭｎＯ４的浓度变化），精密度好（ＲＳＤ＝０．０６％），简便快速，且不受颜色及混浊等干扰，用于中，日，欧等多国僵蚕品种中草酸铵的直接测定，结果与氯化钙沉淀重量法相差－０．２２～０．７８％。     

仪器分析教学中通过实例培养学生的创新能力——电位滴定终点确定的新方法

以电位滴定终点确定新方法探讨研究为例,从5个方面介绍将创新能力培养融入基础课教学的探索。通过该研究提高了学生基础课学习热情与学习质量。首先改进了二次差值微商终点计算方法,通过Excel 计算Δ2E/ΔV-V 二次差值微商法数据表中的最高点与最低点直线线性方程 y=ax+b,令 y=0, x=-b/a即为终点。另外,研究得到了模拟滴定曲线微分法确定电位滴定终点的新方法。用Excel 对滴定曲线进行三次方程模拟即:y=ax3+bx2+cx+d,二次微分后得到: d2y/dx2=6ax+2b, 当d2y/dx2=0,对应的x=-b/3a处即为滴定终点。2     

自动电位滴定法标定硫酸铈溶液和测定硫酸亚铁片中铁含量

采用自动电位滴定法标定硫酸铈溶液,并进行硫酸亚铁片中铁含量的测定。自动电位滴定法以电位突跃监测终点,在45℃~50℃之间,以草酸钠溶液标定硫酸铈溶液,测定值的相对标准偏差(n=5)为0.070%。取硫酸亚铁片1片用0.01mol·L-1硫酸溶液30mL溶解,直接用硫酸铈溶液滴定测定铁含量。方法用于硫酸亚铁片样品分析,回收率为100%,测定值的相对标准偏差(n=5)在1.2%~2.6%之间。     

Catalytic Hydrogen Transfer over Magnesia, xv. Preliminary Studies of Active Centers of Catalysts

Reduction of 7-tridecanone and 1-phenyl-1-hexanone by 2-propanol at 573-673 K in the presence of MgO has been studied. Acidic as well as strong and weak basic sites of MgO surface have been blocked in the reaction of the oxide with triethylamine, phenol or benzoic acid (1000 mol/g of catalyst), respectively. Retention of activity of MgO treated with triethylamine or phenol in ketones reduction by 2-propanol has been observed. Only residual activity of MgO poisoned by benzoic acid has been noted. The exclusive participation of moderate basic centers of MgO in catalytic reduction of ketones by 2-propanol has been ascertained.     

Improved Calcium Ion-Selective Electrode Based on a Neutral Carrier

Abstract

The performance of a liquid-membrane electrode using a synthetic, neutral carrier in o-nitro-phenyl-n-octyl-ether as membrane component in a PVC matrix, in the presence of sodium tetra-phenyl-borate, is described. Selectivities, working range, lifetime and anion interference are discussed. The electrode makes possible the measurement of calcium ion activities in the range 10^?1M to 10^?6M in unbuffered and in the range 10^?1M to 10^?8M in calcium buffered systems respectively. The selectivities of calcium over protons, magnesium, sodium and zinc are 25,000, 26,000, 2,800 and 7,100, respectively, and are far superior than those reported for other calcium sensors.     

以2-苯氧乙基为氮支链的[18]和[15]环系氮支套索冠醚的合成及其络合性能

以2-苯氧乙醇为起始剂, 合成了两种新型氮支套索冠醚: N-(2-苯氧乙基)单氮杂-18-冠-6 (18CE)与N-(2-苯氧乙基)单氮杂-15-冠-5 (15CE). 通过红外光谱、核磁共振氢谱和紫外光谱表征了新冠醚及其中间体的结构. 用电导滴定法研究了两冠醚与Na^＋, K^＋, Ag^＋, NH^4＋, Ni^2＋, Cu^2＋, Pb^2＋和Co^2＋在25 ℃的配位作用, 计算了1∶1配合物的稳定常数. 实验结果表明, 由于N-(2-苯氧乙基)引入氮杂冠醚环和参与配位, 18CE和15CE配合物的稳定常数分别比单氮杂-18-冠-6, N-(2-羟基乙基)单氮杂-18-冠-6, N-(2-甲氧基乙基)单氮杂-18-冠-6和单氮杂-15-冠-5, N-(2-甲氧乙基)单氮杂-15-冠-5, N-(2-甲氧乙基)单氮杂-15-冠-5的对应配合物明显提高. 配合物的稳定常数和紫外光谱皆提供了支链的苯氧基参与配位的信息.     

微波密闭消解难处理K[Au(CN)2]化合物及其Au的精密电位滴定法测定

首次提出了微波密闭消解难处理K[Au(CN)2]化合物的新方法,优化了试液预处理和电位滴定法测定Au的条件,并与英国标准分析方法进行了对照研究.结果表明两种方法的Au分析结果准确度(相对平均误差≤±0.03%)基本一致,但前者结果精密度好(相对标准偏差≤0.02%),消解快速(30 min)、无污染、无损失、经济、简便,符合绿色分析化学的要求,适宜推广应用.