氯乙烯发生亲电加成反应的活性与取向

氯乙烯与氯化氢亲电加成反应的主要产物为1,1一二氯乙烷,符合Markovnikov规则。氯乙烯与HA型化合物的亲电加成都具有相似结果。     

Electrophilic and Nucleophilic Addition of Alkanethiols to 2-Vinyloxyethylmethacrylate

Under acid- or base-catalyzed conditions, thiols add regio- and chemos-electively either to vinyloxy or methacrylate group of vinyloxyalkyl-methacrylates to give polyfunctional methacrylates or polyfunctional vinyl ethers, respectively.     

烯烃亲电加成反应的教学研究

烯烃的典型反应是亲电加成反应.大学有机化学教学目标要求学生掌握并能熟练应用烯烃亲电加成反应的区域选择性、立体选择性以及烯烃的反应活性解决实际问题.具体包括:(1)使用区域选择性预测加成主副产物;(2)使用立体选择性判断加成产物立体结构;(3)综合考虑电子效应,熟练比较各种烯烃的反应活性.由于烯烃亲电加成反应底物多、影响...     

硫氧分子阴离子的QCISD方法研究

使用二次组态相互作用（QCISD）方法和6－311G（d),6-311+G(d),6-311G(2d) 及6－311＋G(2d)基组研究了SO2^-和SO3^-的分子结构，超精细偶数常数（hfcc)及 其对应的分子的绝热电子亲合势（AEA）。发现在QCISD／6－311＋G（2d)水平上计 算的两个分子离子的结构，hfcc值（在^33S和^17O上的）和AEA值与实验值符合得 都很好（除SO^3-中的在^33S上的hfcc值比实验值小23％）。作为比较，我们使用 相同基组作了B3LYP方法计算，得到的超精细偶合常数和AEA值却都与实验符合得不 好。     

离子色谱法测定石膏中的三氧化硫

采用离子色谱法测定石膏中三氧化硫的含量。石膏样品溶解于水中,经超声提取,微孔滤膜过滤,IonPac AS11-HC阴离子交换色谱柱(4mm×250mm)分离,免试剂淋洗液梯度淋洗,电导检测器检测。硫酸盐的质量浓度在20.0~500.0mg·L-1之间与其峰面积呈线性关系。方法应用于石膏标准样品(GBW 03109,GBW 03111)的分析,测定值与认定值相符。加标回收率在80.6%~109%之间,测定值的相对标准偏差(n=6)在1.3%~6.8%之间。     

烯烃亲电加成反应机理的理论探讨

采用PM3方法计算了不同亲电试剂与乙烯生成的中间体正离子的势能曲线．结果显示,当亲电中心原子为价电子层没有d轨道的第一、二周期元素时,开放型中间体正离子的能量比桥型中间体正离子的能量低;此类加成经历开放中间体离子机制进行更为有利,表现出立体非专一性和区域选择性;当亲电中心原子为价电子层有d轨道的第三、四、五周期的元素时,桥型中间体正离子的能量比开放型中间体正离子的能量低;此类加成经历桥型中间体离子机制进行更为有利,表现出立体专一性和区域非专一性．以d-π和s-p-π配位键轨道模型,尝试阐述其内在的轨道控制机制,较好地解释了实验事实．     

Non-catalytic Addition of 1,2,4-Triazole to Nucleophilic and Electrophilic Alkenes

Non-catalytic addition of 1,2,4-triazole to vinyl ethers and esters occurs on heating (65-175°C, 4-20 h) to give Markovnikov adducts (yield 30-100%). Electron-deficient alkenes (acrylonitrile, acrylic acid, 4-phenyl-3-buten-2-one) react with 1,2,4-triazole (78-190°C, 4-20 h) to give anti-Markovnikov adducts in yields of 45-83%.     

Electrophilic Addition Reaction of Ethene with Hydrogen Chloride on Cold Molecular Films: Evidence of Ethyl Cationic Intermediate

We studied the initial‐stage mechanism of the electrophilic addition reaction of ethene with HCl by examining the interactions between ethene and HCl on water‐ice and frozen molecular films at temperatures of 80–140 K. Cs⁺ reactive ion scattering (RIS) and low‐energy sputtering (LES) techniques were used to probe the reaction intermediates that were kinetically trapped on the surface, in conjunction with temperature‐programmed desorption (TPD) mass spectrometry to monitor the desorbing species. The reaction initially produced the π complex of HCl and ethene at temperatures below about 93 K and an “ethyl cationic species” at temperatures below about 100 K. The ethyl cationic species was formed via direct proton transfer from the HCl molecule to ethene with the assistance of water solvation, rather than via the interaction of hydronium ions and ethene. At high temperatures, this species dissociated into ethene and hydronium and chloride ions. The reaction did not, however, complete the final transition state on the ice surface to produce ethyl chloride. The observation gives evidence that the electrophilic addition reaction of ethene occurs through an ethyl‐like intermediate with an ionic character.     

Functional Methacryloyloxy Acetals: V. Electrophilic Addition of Carboxylic Acids to 2-Vinyloxyethyl Methacrylate

Mono- and dicarboxylic acids (acetic, methacrylic, E-crotonic, and malonic) quantitatively add to 2-vinyloxyethyl methacrylate under mild conditions (1 wt % CF₃COOH, 20–60°C, 1–4 h) according to the Markownikoff rule to give the corresponding mono- and bis-adducts with high regio- and chemoselectivity. The products may be regarded as a new family of functionalized methacrylates.     

Conjugate Addition of Grignard Compounds to 2-Benzyl-6-Oxo-Octahydroisoquinoline in the Presence of Copper-Thiophenolate

In the presence of copper-thiophenolate, the conjugate addition of various Grignard compounds to an α, β-unsaturated octahydroisoquinolinone is improved.     

Catalysis of Electrophilic Addition of Alcohols to Alkoxyalkenes by Lithium Salts

Russian Journal of General Chemistry -     

高频红外碳硫分析仪测定石膏矿中的三氧化硫

利用高频红外碳硫仪对石膏矿中三氧化硫含量的测定进行了研究,取得了较好的结果.方法检出限为0.003 0%.用石膏标准样品(GBW03109a,GBW03110)进行分析,测定值与认定值相符,测定值的相对标准偏差(n=9)在0.32%~0.81%之间.使用石膏标准样品(GBW03111)进行本法与国标硫酸钡重量法做比对试验,测定结果无显著性差异.加标回收率为96.4%~104.0%.     

Stereochemical Aspects in the Asymmetric Michael Addition of Chiral Imines to Substituted Electrophilic Alkenes

The Michael-type addition of chiral imines, derived from racemic alpha-substituted cyclanones and optically active 1-phenylethylamine, to electrophilic alkenes, in neutral conditions, constitutes one of the most efficient methods for the stereocontrolled construction of quaternary carbon centers. In order to create an additional stereogenic center at the alpha- or beta-position to the quaternary one, the behavior of a variety of alpha- and beta-substituted alkenyl acceptors was examined. In general, these additions are highly regioselective, the alkylation taking place predominantly, if not exclusively, at the more substituted alpha-side of the imine function; however, in some cases (electrophilic alkenes 28 and 49), significant amounts (10-15%) of regioisomeric adducts were obtained. With the exception of methyl propiolate 52, a remarkable control of the absolute configuration of the adducts were always observed with these Michael acceptors. According to the general rule we have previously proposed, the alkylation process takes place preferentially on the less hindered pi-face of the more substituted secondary enamine, in tautomeric equilibrium with the starting imine. An excellent diastereocontrol was always obtained by using the present alpha- and beta-substituted alkenes. These stereochemical outcomes can be interpreted by invoking that the reaction proceeds through a compact approach of the reactants, the hydrogen atom at the nitrogen center of the enamine being transferred to the alpha-vinylic carbon atom of the acceptor, concertedly with the creation of the C-C bond. In this respect the "endo-approach" 58, in which the electron-withdrawing group of the acceptor faced to the nitrogen atom of the enamine (case of acceptors 10, methyl methacrylate, 24, 28, 43, 47, and 49) largely prevails over the "exo-approach" 59 (case of acceptor 38). This predominant "endo-preference" can be reasonably interpreted in terms of a cooperative effect between steric and stereoelectronic factors.     

Fukui函数和局域软度应用于亲电加成反应的区位选择性的研究

Fukui函数、局域软度、广义Fukui函数以及广义软度通常被称为反应描述符。使用它们研究和探讨了HCl与不对称烯烃以及溴苯硒与不对称苯乙烯的亲电加成反应的区位选择性。在MP2/6-311++G(d, p)理论水平下,采用有限差分方法计算这些反应描述符,同时也使用ABEEMσπ方法进行了计算。ABEEMσπ模型下的局域软度和广义局域软度,分别结合局域硬-软酸碱(HSAB)原理,得出亲电试剂氯化氢与溴苯硒,更容易进攻不对称乙烯和苯乙烯中的马氏碳原子,符合马氏规则。而有限差分方法不能完全地解释该系列反应的区位选择性。此外,主要产物所对应的马氏碳原子的广义局域软度值,就能够预测出此类反应的活性序列,所得结果与速率常数有很好的关联。     

在无机SiO2纳米粒子存在下的苯丙乳液共聚合

研究了在无机SiO₂纳米粒子存在下的苯丙乳液共聚合.选择了能使苯丙乳液稳定存在的乳化剂体系,研究了温度和SiO₂的加入对聚合过程转化率的影响,结果表明,SiO₂的加入对聚合过程有阻聚作用,使单体的转化率降低.SEM照片证明SiO₂粒子已经进入苯丙乳液粒子中,而且SiO₂的加入对乳液制成的膜断面形态有一定影响.实验发现在无机SiO₂纳米粒子存在下,苯丙乳液共聚合时有较多残渣出现,对此通过改进乳液聚合进行了有效地改善.同时对制成的复合材料进行了力学性能和热学性能的测定.     

Reaction of Stannic Chloride with O-Bases in Butyl Acetate

Conductometry and dielcometry were used to show that the reactions of tributyl phosphate, dioctyl methylphosphonate, trioctylphosphine oxide, and hexamethylphosphoric triamide with SnCl₄ in butyl acetate give rise to 1:1 and 2:1 complexes. The enthalpies of the donor-acceptor interaction between the O-bases and SnCl₄ in butyl acetate and the donor numbers of triphenylarsine, trioctylamine oxide, and dioctyl methylphosphonate were determined. The dependence of the enthalpies of the donor-acceptor interaction between the organic oxo bases and SnCl₄ in butyl acetate on the donor number of these bases was found to be linear.