钯催化多氟代芳烃与简单芳烃的氧化C-H/C-H偶联反应机理

运用密度泛函方法研究了醋酸钯催化的五氟苯与苯的氧化C-H/C-H偶联反应机理. 主要考察了以下四种不同可能机理路径：A 苯C-H活化发生在五氟苯C-H活化前,B 五氟苯C-H活化发生在苯C-H活化前,C 苯C-H活化后与五氟苯银化合物发生转金属化,D 首先五氟苯银化合物与醋酸钯转金属化,然后发生苯的C-HH活化步骤. 计算结果表明,两个反应底物(五氟苯与苯)的C-H活化顺序在不同反应条件下是不同的,其中银盐的存在与否是决定因素. 在无银盐条件下,反应的优势路径是机理B. 在银盐存在条件下,五氟苯银盐与钯中心的配位非常容易,但是其生成的中间体难以引导后续的苯环C-H活化步骤,使得整个反应能垒较高. 因此,银盐的存在使得机理C的能量相对优势,该机理与机理A相似. 计算结果与氢/氘交换实验及动力学同位素效应的实验结果一致.     

磺胺-N-苯基J酸分光光度法测定亚硝酸盐研究

筛选了重氮组分和偶合组分。研究了重氮偶合显色反应的条件和方法,提出了借助于磺胺-J酸系列染料中间体(N-苯基J酸、J酸、双J酸)重氮偶合技术分光光度法测定亚硝酸盐。在常温溴化钾共存下,亚硝酸盐在稀盐酸溶液中与磺胺发生重氮化反应,在碳酸钠水溶液中重氮盐与J酸系列染料中间体偶合生成有色偶氮化合物。磺胺-N-苯基J酸偶氮化合物的表观摩尔吸光系数为4.63×104 L·mol-1·cm-1,线性范围为0.003～0.7 mg·L-1,回收率为99.5%～101.6%。相对标准偏差为2.10%。该本方法可用于环境水体中痕量亚硝酸盐的测定。     

汽油机TWC中芳烃演化过程的模拟研究

本文应用蒙特卡罗方法建立了汽油机三元催化器(TWC)芳香烃演化模型,并使用实际发动机的实验结果对该模型进行了验证,结果表明该模型与实际基本相符.同时根据计算证明了,烷基苯催化重整加氢脱烷基生成苯,是三元催化器中苯生成的一个途径.而且发现了三元催化器中苯生成的另一个途径,烷基苯部分氧化生成苯,而且在某些工况该反应起主要作用.     

气相中苯胺分子—分子反应产物的串联质谱研究

用碰撞诱导解离技术研究了苯胺离子－分子反应产物ｍ／ｚ１８７、１８６和１８５离子及其子离子ｍ／ｚ１７０和１６９的碎裂反应特性，由质子化联苯胺和质子化对－氨基联苯及质子化二苯胺的碰撞诱导解离谱，发现由ｍ／ｚ１８７离子生成的ｍ／ｚ１７０离子具有联苯的结构；由ｍ／ｚ１８６离子生成的ｍ／ｚ１６９离子也具有联苯的结构；ｍ／ｚ１８７、１８６和１８５离子不具有联苯胺的结构，在碎裂反应中具有络合物结构。     

N2-苯浮选缔合光度法测定碘的研究

本文依据在强酸性磷酸介质中,Br2氧化I-为I2,进而与I-生成配阴离子I-3,利用溴化十六烷基三甲胺(CTMAB)与I-3发生等离子对缔合物反应,生成缔合物CTMA+*I-3,该缔合物易溶于苯,且在苯中稳定,从而建立了溶剂浮选光度法测碘新方法.本法灵敏度高,选择性强,精密度好,实测了天然水及加碘的盐中碘,结果令人满意.     

Luminol－碳酸钠水溶液的声致发光

作者用Ｌｕｍｉｎｏｌ－碳酸钠水溶液的声致发光拍摄了预置剪纸图案的照片，同时获得了这种溶液的声致发射光谱和光致荧光光谱。分析表明，由Ｌｕｍｉｎｏｌ增强的碳酸钠水溶液的声致发光主要发生在可见光区域；就声致发光和光致荧光的发射波长而言，这种溶液的声激发和光激发具有一定程度的等效性。     

表面张力对PEO稀溶液粘度行为的影响

测定了不同分子量聚氧化乙烯 (PEO)在水和苯溶剂中的粘度 ,发现在低浓度区PEO水溶液的比浓粘度出现负偏离 ,PEO苯溶液比浓粘度与浓度之间依旧满足线性关系 .表面张力测定结果表明 ,PEO分子显著降低了水的表面张力 ,而苯的表面张力则不受影响 .PEO水溶液和纯溶剂水表面张力的不同干扰了高分子溶液和溶剂在粘度计中流过时间的测量 ,导致低浓度区PEO水溶液比浓粘度出现负偏离 .利用PEO水溶液和水表面张力测定结果 ,结合乌式粘度计的几何尺寸 ,定量分析了PEO水溶液和纯溶剂水表面张力的差异对粘度测量结果的影响 ,计算结果与实验结果基本相符 .如果用PEO水溶液流过时间对浓度作图的外推值t0 计算相对粘度 ,可以完全消除PEO水溶液和水表面张力差异对粘度测量的影响     

锰卟啉/钒取代杂多酸配合物的合成、表征和性能研究

利用碘化四对(4-三甲氨基苯基)锰卟啉与钒取代杂多酸H5 PMo10 V2O40,在水溶液中,室温下反应合成了锰卟啉/钒取代杂多酸配合物,用红外和紫外光谱技术对其结构进行了表征,发现该配合物中包含着金属卟啉的环状结构与杂多酸的笼状结构,并且二者以化学键的形式键合在一起.以该化合物作为催化剂,以过氧化氢水溶液为氧化剂,在温和的条件下研究了锰卟啉/钒杂多酸配合物对苯的羟基化反应的影响,考察了催化剂的催化活性,探讨了催化剂对苯羟基化反应的活性中心.研究结果表明,杂多酸中的钒原子是其主要的催化活性中心,锰卟啉的存在可以有效地提高其催化活性.     

煤燃烧中无机矿物向颗粒物的转化规律

为深入理解燃煤颗粒物的形成机理,利用计算机控制扫描电镜技术对煤及其颗粒物中的无机矿物进行了详细表征,研究了煤燃烧过程中主要矿物向颗粒物的转化规律.结果表明煤中粘土矿物由于含有K、Na、Ca、Mg和Fe等杂质元素,容易在较低温度下发生熔融和聚合,从而使颗粒粒径变大.黄铁矿在燃烧中易发生分解、破碎而使颗粒粒径减小,Fe氧化物与硅酸盐发生反应形成富Fe硅酸盐.方解石和铁白云石在高温条件下分解生成对应的氧化物,也可与硅酸盐发生反应形成富Ca或富Fe硅酸盐.石膏在燃烧过程中会经历脱水和分解反应,生成的CaO可与SO3和熔融硅酸盐发生竞争反应.     

J酸分光光度法测定芳香族氨基化合物

综合考虑显色反应选择性、反应速度、灵敏度和偶氮化合物的水溶性等问题,通过对偶合组分分子结构的理论设计和实验筛选,研究了显色反应方法和条件,提出利用J酸(2-氨基-5-萘酚-7-磺酸)作为偶合试剂分光光度法测定水中芳香族氨基化合物。溴化钾催化,室温下,亚硝酸盐与芳香族氨基化合物在稀盐酸水溶液中发生重氮化反应,在碳酸钠水溶液中重氮盐与J酸偶合生成有色偶氮化合物,最大吸收波长480 nm。所测苯胺、4-氨基苯磺酸和1-萘胺的表观摩尔吸光系数分别为3.95×104,3.24×104和3.91×104 L·mol-1·cm-1。水中共存离子影响研究结果表明: 地表水中常见离子对测定结果不产生影响。采用J酸分光光度法测定了上海市复兴岛运河水样,同时,用标准加入法做回收实验,实验结果：苯胺回收率为98.5%～102.1%,相对标准偏差2.08%。J酸是一种常见有机试剂,易溶于水,挥发性低,其毒性大大低于盐酸萘乙二胺。J酸分光光度法测定芳香族氨基化合物具有灵敏度高、选择性好、操作简单快速、测定结果准确等优点,可用于环境水体中痕量芳香族氨基化合物的测定。     

ESR法研究龙胆酸在碱性溶液中的反应

本文用静态毛细管法研究了龙胆酸在醇钠-醇溶液中的反应,主要是氧化反应,发现了属于同一类型三种新的自由基物种,给出了它们的自由基结构模式;龙胆酸在氢氧化钠水溶液中的反应,不仅有氧化还有取代反应,氧化之后紧接着进行取代反应,本文都给予了解释。     

苯甲酸稀土(Eu,La)配合物的红外和荧光光谱研究

用氯化稀土与苯甲酸铵在水溶液中反应,合成了苯甲酸稀土（Ｅｕ,Ｌａ）三元固体系列配合物,其化学组成式为（Ｅｕ１－ｘＬａｘ）Ｌ３（其中Ｌ为Ｃ６Ｈ５ＣＯＯ－,ｘ＝０．０～１．０）。研究了它们的红外光谱和荧光光谱。由红外光谱数据表明,配合物中羧基的对称和反对称伸缩振动吸收峰发生了分裂,而且羧基伸缩振动随着Ｌａ３＋离子含量的增加发生了规律性的变化。荧光光谱实验结果表明,用不发光的Ｌａ３＋离子取代苯甲酸铕中部分Ｅｕ３＋离子可以提高Ｅｕ３＋离子的特征荧光发射强度。     

Estimation of hydroxyl free radicals produced by ultrasound in Fricke solution used as a chemical dosimeter

Hydroxyl free radicals produced in Fricke solution exposed to 80 kV X-rays or 23 kHz ultrasound (intensity 3 W cm⁻²) or 20 kHz ultrasound (intensity 18.9 W cm⁻²) or 3.5 MHz clinical ultrasound (intensity 1.47 W cm⁻²), as estimated from the Fricke dosimetric data, exhibited a linear dose-response relationship. The dosimeter was found to be effective in the concentration range 1.0–8.0 mM of FeSO₄ solution. The hydroxyl radicals produced in Fricke solution were inhibited by the OH radical scavengers dimethyl sulfoxide (200 mM), -histidine (10 mM) and sodium benzoate (10 mM) in a manner proportional to the rate constants of their reaction with the OH radicals. The power threshold for OH radical formation, which is presumably the threshold for cavity formation, was estimated for 23 kHz ultrasound by this dosimeter as 1.28 W cm⁻² for a 4 cm³ sample volume.     

CIR技术红外光谱法应用研究

本文描述了通过使用CIR装置技术，实现了水溶液红外光谱分析。由三氮唑核苷、苯甲酸钠、乙酸钠等水溶液进行红外光谱分析研究，得到各自水溶液直接测定的红外光谱，并进行了定量分析研究，效果良好，说明了CIR技术具有较好的实用价值。     

Barium isotope fractionation during experimental formation of the double carbonate BaMn[CO3]2 at ambient temperature

In this study, we present the first experimental results for stable barium (Ba) isotope (¹³⁷Ba/¹³⁴Ba) fractionation during low-temperature formation of the anhydrous double carbonate BaMn[CO₃]₂. This investigation is part of an ongoing work on Ba fractionation in the natural barium cycle. Precipitation at a temperature of 21±1°C leads to an enrichment of the lighter Ba isotope described by an enrichment factor of?0.11±0.06‰ in the double carbonate than in an aqueous barium-manganese(II) chloride/sodium bicarbonate solution, which is within the range of previous reports for synthetic pure BaCO ₃ (witherite) formation.     

Ultrasound induced aqueous polycyclic aromatic hydrocarbon reactivity

An investigation to determine the ability of ultrasonic radiation to chemically alter polycyclic aromatic hydrocarbons (PAHs) in aqueous solution has been conducted. The data indicate that chemical alteration of PAHs can be induced under intense ultrasonic treatment. The extent and outcome of reaction is a function of irridation time and aqueous solution parameters. Reaction products were analysed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Reaction products from ultrasonic treatment of aqueous solutions of biphenyl include ortho, meta, and para-1,1 biphenols. The principal product from ultrasonic treatment of aqueous phenanthrene solutions appears to be a phenanthrene-diol. The number and composition of reaction products for both PAHs tested suggest that a free radical mechanism is likely during aqueous high intensity ultrasonic treatment. The use of ultrasound to treat PAH contaminated aqueous solutions in tandem with other methodologies appears promising. However, the toxicity of reaction products produced by treatment remains to be determined.     

Partial oxidation of higher olefins on Ag(1 1 1): Conversion of styrene to styrene oxide, benzene, and benzoic acid

Temperature programmed reaction spectroscopy (TPRS), X-ray photoelectron spectroscopy (XPS), and reflection absorption infrared spectroscopy (RAIRS) were used to study the partial oxidation of styrene on Ag(1 1 1). Styrene oxide, benzene, and benzoic acid were identified as partially oxidized reaction products. XPS and RAIRS provide evidence for the formation of a styrene-derived surface oxametallacycle that either forms styrene oxide or is further oxidized in a branching reaction to form benzoate, which is the intermediate responsible for the formation of both benzene and benzoic acid. The strong dependence of the product distribution on oxygen coverage suggests that O monomers adsorbed on Ag(1 1 1) provide a higher selectivity for partial oxidation than oxygen from the Ag(1 1 1)-p(4 × 4)-O reconstruction.     

Adsorption and reduction reactions of anthraquinone derivatives on gold electrodes studied with electrochemical surface‐enhanced Raman spectroscopy

Electrochemical surface‐enhanced Raman spectroscopy (EC‐SERS), combined with cyclic voltammetry, and the density functional theoretical (DFT) method were used to investigate self‐assembled monolayer (SAM) adsorption and reduction processes. Here, we choose the system of interest, being thiolacetyl‐terminated 2‐phenylene ethynylene‐substituted anthraquinone molecule (2‐AQ) on gold electrodes in buffered aqueous and aprotic solutions. In the buffered aqueous solution, the results of cyclic voltammetry and EC‐SERS measurements, as well as DFT calculations, indicate that the adsorbed molecules pass through a two‐electron two‐proton reduction reaction with cathodic polarization. In particular, the latter two methods confirmed the structural changes of SAMs during the process of redox reaction, 2‐AQ + 2e + 2H⁺ → 2‐AQH₂, where 2‐AQ and 2‐AQH₂ are the oxidized and reduced forms, respectively. In aprotic solutions (acetonitile), a stepwise reaction mechanism was proposed on the basis of the results of EC‐SERS and DFT calculations. The first reduction peak should be a half reaction process 2‐AQ + e → 2‐AQ⁻, where 2‐AQ⁻ is a single electron reduced form. Compared with that of 2‐AQ SAMs in the buffered aqueous solution, the results of EC‐SERS and DFT calculations in aprotic solution suggested that the solvent effect significantly influences the redox process of 2‐AQ in electrochemical interfaces. Copyright © 2012 John Wiley & Sons, Ltd.     

运用表面增强拉曼散射(SERS)和密度泛函数理论(DFT)模拟计算研究对硝基苯胺在金纳米颗粒表面吸附行为

在沉积金纳米颗粒的干燥滤纸上进行对硝基苯胺的表面增强拉曼散射(SERS)光谱研究,并与对硝基苯胺在金胶水溶液中的表面增强拉曼散射(SERS)光谱相比,分子拉曼光谱发生了很大变化。同时利用DFT理论计算对硝基苯胺在金胶颗粒上的吸附行为的拉曼光谱。DFT理论模拟计算和FI-Raman实验分析都表明这种变化源于对硝基苯胺的不同吸附方式。SERS和DFT结合研究分子的吸附是一种有效的技术。     

Probing PAH formation chemical kinetics from benzene and toluene pyrolysis in a single-pulse shock tube

Benzene and toluene were pyrolyzed under highly argon-diluted conditions at a nominal pressure of 20 bar in a single-pulse shock tube coupled to gas chromatography/gas chromatography–mass spectrometry (GC/GC–MS) diagnostics. Concentration evolutions of polycyclic aromatic hydrocarbon (PAH) intermediates were measured in a temperature range of 1100–1800 K by analyzing the post-shock gas mixtures. Different PAH speciation behaviors, regarding types, concentrations and formation temperature windows, were observed in the two reaction systems. A kinetic model was proposed to predict and interpret the measurements. Through a combination of experimental and modeling efforts, PAH formation patterns from species pools of benzene and toluene pyrolysis were illustrated. In both cases, channels leading to PAHs basically originate from the respective fuel radicals, phenyl and benzyl. Due to the higher thermal stability of benzene, the production of phenyl, and thus most PAH species, occur in higher temperature windows, in comparison to the case of toluene. In benzene pyrolysis, benzyne participates in the formation of crucial PAH species such as naphthalene and acenaphthylene. Phenyl self-recombination takes considerable carbon flux into biphenyl, which serves as an important intermediate leading to acenaphthylene through hydrogen loss and ring closure. The resonantly-stabilized benzyl is abundant in toluene pyrolysis, and its decomposition further produces other resonantly-stabilized radicals such as fulvenallenyl and propargyl. Barrierless addition reactions among these radicals are found to be important sources of PAHs. Fuel-specific pathways have pronounced effects on PAH speciation behaviors, particularly at lower temperatures where fuel depletion is not completed within the reaction time of 4.0 ms. Contributions from the commonly existing Hydrogen-Abstraction-Carbon-Addition (HACA) routes increase with the temperature in both cases.