硫脲氧化反应动力学研究进展

本文综述了硫脲氧化反应动力学的研究进展,根据氧化剂和氧化方式不同,将硫脲氧化体系分成含卤氧化体系和非卤氧化体系两大类,其中含卤氧化体系包括亚氯酸、碘酸、溴酸、卤素单质氧化硫脲的反应体系;非卤氧化体系包括双氧水、自由基、电化学和金属酸盐氧化硫脲的反应体系。总结了不同反应体系的动力学现象和反应机理研究状况,文中还介绍了在硫脲氧化反应动力学研究中光电磁及色谱方法的发展状况,提出硫脲氧化反应动力学机理研究突破可能途径。     

氨基酸氧化反应的动力学研究

利用紫外吸收光谱谱法研究了α－氨基酸与Ｎ－溴代琥珀酰亚胺（ＮＢＳ）进行氧化反应的动力学，结果表明：反应对ＮＢＳ为一级，对α－氨基酸为正分数级，准一级反应速率常数ｋｏｈａ随（ＯＨ＾－）增加而降低，离子强度及扩散效应对反应无影响，提出了反应的可能机理，导出的速率方程圆满地解释了实验现象，并且计算出了速控步的速率常数、前期平衡常数等动力学参数。     

碱性介质中二过碘酸合铜(Ⅲ)配离子氧化乙二醇和丙二醇-1, 2的动力学及机理

本世纪五十年代以来,二过碘酸合铜(Ⅲ)和二过碲酸合铜(Ⅲ)配离子作为氧化剂在糖类、氨基酸。蛋白质、羧酸和醇类等的定量测定中得到了广泛的应用。近期Movius和Murthy等人进行了Cu(Ⅲ)对一元醇、醛等有机物的氧化反应动力学研究。Cu(Ⅲ)处于高价氧化态,这类反应体系又比较复杂,对这类反应体系进一步探讨有一定的意义,因为铜在许多包含有电子转移的生物化学过程中起着重要作用。本文在25℃,碱性介质中就Cu(Ⅲ)对乙二醇和丙二醇-1,2(统称,α-二醇,或α-diol)的氧化反应动力学进行了研究。     

一种同时测定贝类中谷胱甘肽和游离氨基酸的方法

<正>申请公布号:CN106443028A申请公布日:2017.02.22申请人:上海海洋大学摘要本发明属于化学分析检测领域,特别涉及同时测定贝类中谷胱甘肽和游离氨基酸的方法。该方法优化了样品前处理程序,对分离树脂有保护作用,有利于分离,同时氨基酸提取效率更高,添加了抗氧化剂,防止谷胱甘肽被氧化,使用自制的国产缓冲液和反应液,通过改变缓冲液的p H和洗脱     

电喷雾串联质谱研究黄芩苷与谷胱甘肽的相互作用

建立了研究黄芩苷和谷胱甘肽的相互作用的电喷雾多级串联质谱方法,结果表明黄芩苷首先自氧化生成黄芩苷半醌,随后黄芩苷半醌与谷胱甘肽进一步发生反应,生成谷胱甘肽与黄芩苷加合物,该化合物不稳定,可进一步发生自氧化、水合反应或脱糖醛酸等反应.利用串联质谱技术鉴定了谷胱甘肽与黄芩苷的结合位点是在黄芩苷苷元的C8位.该方法从分子水平...     

谷胱甘肽与D型氨基酸非共价复合物的质谱

为了研究谷胱甘肽和D型氨基酸的非共价相互作用, 将一定化学剂量比的还原型谷胱甘肽与D-苯丙氨酸、D-组氨酸或D-谷氨酰胺在室温下混合后, 温育1 h, 使反应达到平衡. 电喷雾质谱测量结果表明, 在生理pH条件下, 谷胱甘肽可以和D 型氨基酸经反应生成非共价复合物. 串级质谱中的碰撞诱导解离(CID)以及紫外光谱进一步确认了非共价复合物的生成. 为了避免严重的离子化效率和质谱信号相互抑制作用, 对谷胱甘肽和D-谷氨酰胺的相互作用作了定量的评估. 配制一系列不同初始浓度的谷胱甘肽和D型氨基酸的混合溶液, 并用电喷雾质谱测定混合溶液中不同质点的质谱峰强度, 计算了谷胱甘肽与三个D型氨基酸结合形成的复合物的解离常数. 计算结果表明, 谷胱甘肽可以和D型氨基酸结合形成不同键合强度的非共价复合物, 其稳定性按照D-谷氨酰胺、D-苯丙氨酸、D-组氨酸的次序逐渐增大.     

反相胶束膜模拟体系中氨基酸的光敏化氧化

研究了AOT/H_2O/甲苯反相胶束体系中,光敏剂H[TBC(O~iPr)_4P(OH)]的光化学性质及其对氨基酸的光敏化氧化.结果表明,反相胶束可促使光敏剂解聚,并提高其敏化产生和~1O_2~-的效率,溶于反相胶束水团中的色氨酸和酪氨酸可被H[TBC(O~iPr)_4P(OH)]光敏化氧化,反应以Ⅱ型机制(~1O_2)为主.氨基酸光氧化动力学研究表明,反相胶束所形成的微多相体系可改变光敏化反应的途径和动力学控制因素.     

2,2,6,6-四甲基哌啶氧化物自由基选择性氧化反应用于羟丙基化半乳甘露聚糖C-6位取代度的表征研究

TEMPO (2,2,6,6-四甲基哌啶氧化物自由基)-NaClO-NaBr是一种对伯羟基具有很高选择性的氧化反应体系, 系统研究了该体系对半乳甘露聚糖及其衍生物的氧化反应过程, 通过对氧化反应中NaOH消耗量的适时跟踪测定, 确定了氧化反应进程以及氧化反应终点, 利用FTIR和13C NMR对氧化产物的结构进行了表征, 进一步确证了TEMPO氧化体系可高选择性地将C-6位伯羟基完全氧化为羧酸. 首次将TEMPO氧化法用于羟丙基化半乳甘露聚糖C-6位取代度的测定, 利用氧化反应NaOH的消耗量计算出不同摩尔取代度的羟丙基半乳甘露聚糖C-6位伯羟基的取代度. 以此为依据, 对半乳甘露聚糖的羟丙基化反应机理进行了初步探讨, 从实验上进一步验证了半乳甘露聚糖羟丙基取代反应优先发生在C-6位伯羟基上.     

微反-色谱-DTA联合装置及乙醇催化氧化脱氢反应动力学的研究

国外,对银催化甲醇氧化脱氢制甲醛的反应动力学曾进行了研究,但对乙醇催化制乙醛的反应动力学,未见到研究报导。本文用自己组装的微反-色谱-DTA联合装置进行了乙醇催化氧化脱氢反应动力学的研究。     

金属卟啉催化环己烷羟基化反应中环己酮的形成机理研究

单金属卟啉和双金属卟啉催化下PhIO常温氧化环己烷的羟基化反应中金属卟啉结构和反应溶剂、反应温度、反应时间等环境因素对产物酮含量及酮形成反应动力学的影响进行了系统研究, 并与金属卟啉催化下PhIO氧化环己醇的反应进行了对比, 提出了金属卟啉催化下环己烷羟基化反应中产物酮的形成机理。     

Dilation kinetics of glassy,aromatic polyimides induced by carbon dioxide sorption

Over the past years, the equilibrium sorption of gases in polymers has been intensively studied. Mostly, glassy polymers were investigated because of their excellent selective mass transport properties. This work does not focus on the equilibrium sorption but on the kinetics to reach the equilibrium. We developed a new experimental method measuring the sorption-induced dilation kinetics of a polymer film. Carbon dioxide and glassy, aromatic polyimides were chosen as model systems. Low-pressure experiments demonstrate that the measured dilation kinetics represent the sorption kinetics. A significant delay between the sorption and dilation kinetics is based on the fact that dilation kinetics occurs simultaneously with the concentration increase in the center of the polymer film. High-pressure experiments reveal significant differences in dilation kinetics compared to low-pressure experiments. Generally, three regimes can be distinguished in the dilation kinetics: a first, fast volume increase followed by two much slower regimes of volume increase. The magnitude of fast and slow dilation kinetics strongly depends on the swelling history of the polymer sample. The results of the experiments are analyzed in the light of a model relating the fast dilation kinetics to a reversible “Fickian” dilation and the slower dilation kinetics to an irreversible, relaxational dilation. © 1995 John Wiley & Sons, Inc.     

Electrical properties and defect chemistry of TiO2 single crystal. IV. Prolonged oxidation kinetics and chemical diffusion

Measurements of both electrical conductivity and thermoelectric power were used to monitor the equilibration kinetics of undoped single-crystal TiO(2) during prolonged oxidation at 1123 and 1323 K and p(O(2)) = 75 kPa. Two kinetics regimes were revealed: kinetics regime I (rapid kinetics), which is rate-controlled by the transport of oxygen vacancies, and kinetics regime II (slow kinetics), which is rate-controlled by the transport of titanium vacancies. The incorporation of titanium vacancies allows undoped p-type TiO(2) to be processed in a controlled manner. The kinetics data were used to determine the chemical diffusion coefficient (D(chem)) associated with the transport of titanium vacancies, which is equal to D(chem) = 8.9 x 10(-14) m(2) s(-1) and D(chem) = 9.3 x 10(-15) m(2) s(-1) at 1323 and 1123 K, respectively.     

The kinetics of enantioselective hydrogenation of methyl acetoacetate using a modified Raney nickel catalyst

The kinetics of enantioselective hydrogenation of methyl acetoacetate using Raney nickel modified by (2R,3R)-(+)-tartaric acid were studied, thereby focusing on the effects of the reaction conditions on the enantioselectivity. Reactions were carried out in a liquid phase under atmospheric and increased hydrogen pressure. The reaction course was described by the exponential kinetics model and by Langmuir-Hinshelwood kinetics assuming the existence of two types of active sites on the catalyst surface, selective and non-selective. Using Langmuir-Hinshelwood kinetics, the acquired parameters were used for discussion of the effects of the reaction conditions on the enantioselectivity and the mechanism of the enantioselective hydrogenation.     

锌蒸气的氧化行为与氧化锌的结晶形貌

用热重法测定了不同气氛下锌蒸气的氧化动力学曲线,用扫描电镜跟踪观察分析了产物的结晶形貌,结果表明,氧化动力学遵守直线规律时,产物是无定形、颗粒状和单针状的ZnO;氧化动力学为抛物线规律时,产物是四针状或多针状的ZnO.动力学转变规律的原因是锌蒸气中气态锌原子与凝聚生成的锌液滴之间存在动态平衡,气态锌原子的氧化过程遵守直线规律;而锌液滴的氧化过程分为两个阶段,分别受收缩球状界面反应模型R₃和三维扩散模型D4动力学控制,表观活化能分别为106.3～108.2和114.2～117.3kJ/mol;扩散过程实际上是锌原子通过氧化膜层由里向外扩散,扩散系数D=2.46～9.70×10^-5cm²/s.     

Specific liquid DNA hybridization kinetics measured by fluorescence polarization

The kinetics of specific DNA hybrid formation were monitored directly in solution. Detection was based on fluorescence polarization measurements of labelled oligonucleotides at different stages during the hybridization. The effect of mismatched base pairs on the kinetics was measured. Significant differences could be observed in the kinetics when as few as three mismatches were introduced by the polymerase chain reaction technique in the target DNA sequences.     

自由基聚合速率的深入讨论

自由基聚合是高分子化学课程中的重要一章,自由基聚合动力学(包括聚合速率、平均相对分子质量及分布)是教学中的重要内容。本文讨论了建立自由基聚合微观动力学模型的基础:三个基本假设和四个简化条件,阐释了传统单官能度引发剂引发的聚合体系速率方程推导中这些假设和条件的运用,并扩展到双官能度引发剂体系,得到基元反应速率和总速率。提出从三个层次讨论影响自由基聚合速率的因素,深化了对自由基聚合速率教和学。     

C302铜基催化剂上甲醇合成的动力学研究 Ⅱ.动力学模型的工业检验

以Ｌｕｒｇｉ型甲醇合成反应器一维非均相数学模型和单颗粒催化剂反应－扩散模型为基础,通过模拟分析及与工业生产数据相对照的方式,对六种具有不同结构的Ｃ３０２催化剂动力学模型进行了工业应用检验,将六种模型用于非等温工业反应器性能分析时,有的模型模拟结果偏离实际情况较远,表明动力学模型结构对反应器模拟结果有较大的影响,有必要对用等温动力学实验数据和方法确立的动力学模型从工业应用角度做进一步检验。基于这一观点,最终确定了三种比较适宜于工业应用的Ｃ３０２催化剂的动力学模型。     

Kinetics of successive seeding of monodisperse polystyrene latexes. II. Azo initiators with and without inhibitors

Oil soluble azo initiators in combination with water soluble inhibitors were used to extend the particle size limit in studies of the kinetics of successive seeding of monodisperse polystyrene latexes. Monodisperse latexes were prepared up to 2.5 μm in diam using 4.0 mM AMBN and 14.5 mM hydroquinone with a constant 15% emulsifier (Aerosol–MA) surface coverage throughout the seven step sequence. The polymerization kinetics were measured in a piston/cylinder dilatometer designed for microgravity experiments. The Interval III kinetics were dominated by the gel effect although these were affected by the nature of the inhibitor. In general, the overall polymerization rate decreased with increasing particle size (decreasing N_p) up to a size of about 1 μm. Thereafter, the kinetics were independent of these variables, exhibiting Smith-Ewart Case 3 (bulk) kinetics. The initiator efficiencies were found to be of the order of 10%, considerably lower than reported for bulk polymerizations.     

两种表征金属有机双层膜络合和金属薄膜氧化反应动力学的方法

建立了两种新的薄膜反应动力学表征方法, 即透射光谱法和方块电阻法, 以克服传统动力学表征手段在薄膜体系氧化与络合反应过程中应用的局限性. 以透射光谱为表征手段, 得到了Ag/TCNQ(四氰基对醌二甲烷)金属有机双层薄膜的络合反应动力学曲线; 以方块电阻为表征手段, 得到了Cu薄膜的氧化反应动力学过程.     

超声辐照引发MMA微乳液聚合动力学研究

用自由基捕捉剂N,N-二苯基-2,4,6-三硝基苯肼基(DPPH)进行超声辐照引发甲基丙烯酸甲酯(MMA)微乳液聚合引发过程的动力学研究,结果表明,所得速率常数比超声辐照引发纯单体聚合的速率常数大一个数量级,说明超声辐照在微乳液聚合体系中的引发作用远远强于本体聚合;得到的表观活化能为正值,说明升温有利于超声辐照引发微乳液聚合.对聚合过程动力学的研究表明,引发剂用量决定聚合反应速率曲线恒速期的长短.