Konzentrationseffekte in Isocyanat-Alkohol-Systemen

Summary The reaction between aromatic isocyanate and alcohol in nonpolar solvents at different alcohol and isocyanate concentrations and the effect of the presence of urethane in this solution at the start of the reaction have been examined. The results indicate that the rate constants of the observed second-order equation are dependent on the concentration of the reactants and of the urethane.

     

Polarographische Untersuchung der Kinetik der Polymerisation von Methylvinylketon

The homogeneous polymerization of methyl-vinyl ketone in diluted methanol solutions in presence of proton donors is studied using the polarographic method. The effect of the cation of the indifferent electrolyte is investigated as well as the influence of small quantities of H₂O. Suggestions were made about the possible mechanisms of these influences in the general scheme of the process proposed byHolleck et al.

     

甲烷与PtCl2（H2O）x（x=0,1,2）的配合物结构的从头算研究

本文用量子化学从头算方法研究了甲烷与配位不饱和ＰｔＣｌ２（Ｈ２Ｏ）ｘ（ｘ＝０，１，２）形成的σ配合物的结构和性质。通过ＲＨＦ／Ｌａｎ１２ＤＺ和ＭＰ２／Ｌａｎ１２ＤＺ水平计算讨论了溶剂Ｈ２Ｏ分子与位的影响。在ＲＨＦ／Ｌａｎ１２ＤＺ级别上有４个稳定的（ＣＨ４）ＰｔＣｌ２配合物，分别属于η＾３，η＾２，η＾３，并都具有Ｃｓ对称性。根据能量和结构分析，η＾１配合物是进一步氧化加成反应的可能的起始物。     

DFT calculations on the retro-ene reactions, part II: allyl n-propyl sulfide pyrolysis in the gas phase

The mechanism and kinetic aspects of the retro-ene reaction of the Allyl n-propyl sulfide and its deuterated derivative were studied using four different types of density functional theory methods with eight different levels of the basis sets. The activation energies were determined at 550.65 K. As a consequence of our calculations, a transition state is concluded that consists of a polar six-center cyclic structure. We found that the combination B3PW91/6-311++G** produces activation energy values closer to the experimental ones, but the simpler combination B3LYP/6-31G* produces excellent values too in less time. Our calculations show that the activation parameters obtained from the B3 methods are better than those obtained using the BLYP method. The mechanistic studies on the reaction show that the reaction proceeds through an asynchronous concerted mechanism. Theoretical calculations indicate that the reaction displays a kinetic isotope effect of 2.86 at 550.65 K.     

In Vitro and In Vivo Effects and Safety Assessment of Corn Peptides on Alcohol Dehydrogenase Activities

The in vitro and in vivo effects of corn peptides(CPs) prepared from corn gluten meal by proteolysis with an alkaline protease and fractions of CPs from Sephadex G-15 and G-10 columns on activities of alcohol dehydrogenase(ADH) were studied. The results show that CPs and fraction 3 of CPs from Sephadex G-10 column enhance in vitro ADH activity. Furthermore, the in vitro accelerating effect of the fraction 3 of CPs on ADH activity was superior to that of glutathione, which was also found even in the presence of ADH inhibitor, such as pyrazole. In the in vivo experiments, the animals were fed with different dosages of CPs and with a dose of Chinese distilled spirit orally, and sacrificed for the measurement of ADH activity. In vivo experimental results indicate that CPS enhanced hepatic ADH activities. To test the safety of CPs as health food, 30 d feeding test was performed. No obvious toxic effects were detected in treated Wistar rats.     

Zur Calorimetrie der Bismutoxidhalogenide 1. Bismutoxidchloride

Calorimetry of Bismuth Oxidehalogenides. 1. Bismuth Oxidechloride The heat of solution of all known solid phases in the system Bi₂O₃? BiCl₃ in 4n HCl was investigated. To compare the data they were converted to the standardized formula Bi₂O_3?y/2Cl_y with 0 ≤ y ≤ 2. The enthalpies of formation of the complex bismuthoxidechlorides are based on the enthalpies of Bi₂O_{3, f}, HCl,_Lsg and H₂O circumventing the value for Bi(OH)_{3, Lsg}. The data see “Inhaltsübersicht”.     

Solid–solid interactions between ferric and cobalt oxides as influenced by Al2O3-doping

The solid–solid interactions between pure and alumina-doped cobalt and ferric oxides have been investigated using DTA, IR and XRD techniques. Equimolar proportions of basic cobalt carbonate and ferric oxide and different amounts of aluminum nitrate were added as dopant substrate. The amounts of dopant were 0.75, 1.5, 3.0 and 4.5 mol% Al₂O₃.

The results obtained revealed that solid–solid interaction between Fe₂O₃ and Co₃O₄ takes place at temperatures starting from 700°C to produce cobalt ferrite. The degree of propagation of this reaction increases progressively as a function of precalcination temperature and Al₂O₃-doping of the reacting solids. However, the heating of pure mixed solids at 1000°C for 6 h. was not sufficient to effect the complete conversion of the reacting solids into CoFe₂O₄, while the addition of a small amount of Al₂O₃ (1.5 mol%) to ferric/cobalt mixed solids followed by precalcination at 1000°C for 6 h conducted the complete conversion of the reacting solids into cobalt ferrite. The heat treatment of pure and the 0.75 mol%-doped solids at 900 and 1000°C effected the disappearance of most of IR transmission bands of the free oxides with subsequent appearance of new bands characteristic for the CoFe₂O₄ structure. An increase in the amount of Al₂O₃ added from 1.5–4.5 mol% to the mixed solids precalcined at 1000°C led to the disappearance of all bands of free oxides and appearance of all bands of cobalt ferrite. The promotion effect of Al₂O₃ in cobalt ferrite formation was attributed to an effective increase in the mobility of the various reacting cations. The activation energy of formation (ΔE) of CoFe₂O₄ phase was determined for pure and doped solids. The computed values of ΔE were, respectively, 99.6, 87.8, 71.9, 64.7 and 48.7 kJ mol⁻¹ for the pure solid and those treated with 0.75, 1.5, 3 and 4.5 mol% Al₂O₃.     

聚苯胺用作乙醇脱氢反应中的电子传递介质

脱氢酶（ADH）在电化学氧化还原反应中是很重要的一种酶,但它在催化有机分子脱氢反应时需烟酰胺腺嘌呤二核苷酸（NAD＋）参与,后者从底物接收电子生成还原形NADH.脱氢酶电极是根据NADH的电化学氧化产生的阳极电流构成的[1－3].然而NADH与裸体炭电极和铂金电极之间的直接电子传递是非常困难的,往往需一个相当高的过电位[4].另一个问题是生成物易将电极玷污[5,6].克服这些问题的方法是使用均相电子传递介质,例如在底物溶液中加入Meldola蓝、Nile蓝A和NMP＋甲替硫酸盐等[7－9],及复相电子传递介质,例如将镍六氰基高铁酸盐固…     

Beiträge zur Chemie der Pyrrolpigmente, 43. Mitt.

ByLambert–Beer-experiments at different temperatures in the range from 290 to 80K of solutions containing Bilirubin (2), its dimethylester3, its dimethoxydimethylester derivative4 and aetiobilirubin-IV- (1) in 2-methyltetrahydrofurane the preponderance of an association equilibrium determining the spectral changes upon cooling in the case of1 and3 was deduced. By protonation studies of partial structures5 and6 as well as of the integral pigments3 and4 the lactam-lactim equilibrium was proved to be on the side of the lactam tautomer at low temperatures as well. Upon cooling a zwitterionic species was detected in case of compound2. The conformational aspects in cases where a disturbance by the equiblibria given above could be ruled out are discussed. A warning is given to use low temperatures measurements of absorption and luminescence properties to gain structural and photochemical informations without previously establishing the nature of the solutions very carefully.

     

离子交换树脂催化合成丙烯酸—β—羟乙酯的动力学研究

对732~#强酸型离子交换树脂催化合成丙烯酸-β-羟乙酯进行了动力学研究。测定并推算出反应级数、反应速率常数及活化能,提出了反应机理。     

Zur Calorimetrie der Bismutoxidhalogenide. II. Bismutoxidbromide

Calorimetry of Bismuth Oxidhalides. II. Bismuth Oxidebromides The heat solution of all known solid phases in the system Bi₂O₃/BiBr₃ in 4n HBr were investigated. To compare the data they were converted to the standardized formula Bi₂O_3?y/2Br_yBr_y with 0 ? y ? 2. The enthalphies of formation of the complex bismuthoxidebromides are based on the enthalpies of Bi₂O_3,f HBr_,Lsg and H₂O circumventing the value for Bi(OH)_3,Lsg.     

二羟基二(原碘酸根)合镍(Ⅳ)配离子氧化乙醇的反应动力学及机理

在碱性介质中用分光光度法研究了二羟基二(原碘酸根)合镍(Ⅳ)配离子(DDN)于25～40℃区间氧化乙醇的反应动力学。结果表明,反应对DDN为一级,对乙醇为正分数级。准一级速率常数k_obs随[OH^-]增加而增大,随[IO₄^-]增加而减小。有微弱的负盐效应。在氮气保护下,反应不能引发丙烯酰胺的聚合。提出一个包括Ni(Ⅳ)和乙醇生成加合物前期平衡的反应机理,导出的速率方程满意地解释了所有的实验结果,并计算出平衡常数、速控步骤的速率常数及相应的活化参数。     

用数据处理新模型测定H2O2分解的活化能

对H2O2催化分解传统实验的数据处理方法和实验手段中存在的问题进行了分析,并通过优化配置,结合一级反应数据处理新模型不用测定V∝的理论和皂膜流量计短时间量气稳定性好的优点,共同完成了H2O2催化分解的动力学测定实验,不仅解决了实验过程的稳定性问题,而且打破了传统实验中只能测定一个温度下的速率常数的局限,同时在准确测定多个温度下的速率常数基础上求出了该反应的活化能,从而丰富了实验内容,提升了实验水平,从根本上改善了传统实验中存在的诸多问题。     

Poly(ether ether ketone)/poly(aryl ether sulphone) blends: thermal degradation behaviour

The thermodegradative behaviour of blends of poly(ether ether ketone) (PEEK) and poly(aryl ether sulphone) (PES) was studied by dynamic thermogravimetry in order to analyze their thermal stability. The Freeman-Carrol differential approach was used to determine the kinetic parameters i.e. the apparent activation energy (E_a) and order of reaction (n), of the degradation process. The results indicate that the presence of one component influences the thermal stability of the other. Both, temperature for 5% weight loss (T₅) and E_a for blends show a negative deviation from the linear behaviour, which signifies a lowering of thermal stability compared to homopolymers. The decrease in the thermal stability at low concentration of PES in PEEK has been explained on the basis of chemical interactions of the degradation products of PES, which has lower induction temperature for degradation, with PEEK and also on the reduction of viscosity of the medium. But the decrease in thermal stability at low concentration of PEEK in PES is unusual and at present, without the complete elucidation of degradation mechanism in these blends, is difficult to explain.     

Monodisperse micron-sized cross-linked polystyrene particles. VI. Understanding of nucleated particle formation and particle growth

 The procedure of nucleated particle formation and particle growth in dispersion polymerization was studied with the intention of understanding the production of monodisperse polystyrene particles cross-linked with urethane acrylate (UA). The time required for the formation of primary particles was determined exactly from the turbidity measurement of the reaction mixture with the polymerization time. It could be found that differing from conventional divinyl cross-linkers, such as divinylbenzene, UA had a boundary concentration where the association and coagulation of preformed nuclei with other oligomers and/or nuclei effectively took place until the primary particle formed. Similarly to linear polystyrene particles, the particle number density of the primary particles cross-linked with UA remained constant to the final particles. This observation verifies the suggestion that the primary particles cross-linked with UA readily absorbed the monomers from the medium during the stage of particle growth. Received: 31 August 1999 Accepted: 7 January 2000     

四苯硼酸盐的热化学研究——Ⅱ.一价四苯硼酸盐的标准生成焓

本文用自行建立的精密溶解层热装(?)测定了298.15K时,NH_4BPh_4、KBPH_4、RbBPh_4、CsBPh_4、TlBPh_4、AgBPh_4和HgPh_2七种沉淀反应的反应焓,由此计算了一价四苯硼酸盐的标准生成焓、熵及吉布斯自由能.     

Bestimmung der Bildungsenthalpie von SmOCl durch Lösungskalorimetrie

Determination of the Enthalpy of Formation of SmOCl by Solution Calorimetry The enthalpy of formation of SmOCl (ΔH(SmOCl_f, 298) = —239.9 ± 0.5 kcal/mol) was determined from the heat of solution of SmOCl (ΔH_L(SmOCl_f298) = —31.24 ± 0.15 kcal/mol) on the base of the enthalpies of formation of Sm₂O₃ and SmCl₃ and their heats of solution in 4n HCl.     

Conductometric Study of Potassium Bromide in 2-Butanol + Water Mixtures

Molar conductivities of dilute solutions of KBr in 2-butanol + water mixtures with an alcohol mass fraction of 0.70, 0.80, 0.90 and 0.95 were determined at five temperatures from 288.15 to 308.15 K. Data were treated by the Lee-Wheaton conductivity model and its parameters, the limiting molar conductivity (Λ _o) and the association constant (K _A ), were evaluated. Thermodynamic quantities for the ion-association reaction and for the process of charge transport were derived from the temperature dependence of the parameters and, together with the Walden product, interpreted in terms of the ionic size as well as solvent basicity, structure and permittivity.     

四-对磺酸基-苯基卟啉铁(Ⅲ)的轴向配位快速反应动力学研究

用UnionGikenRA-410温度跃变紫外可见分光光度计研究了二聚的四-对磺酸基-苯基卟啉铁[Fe(Ⅲ)TPPS₄)_D]与咪唑(Im)、2-甲基咪唑(MeIm)、2-乙基-4-甲基咪唑(EMIm)轴向配位快速反应动力学。提出了反应机理,研究了轴向配体和温度对反应的影响,应用Gauss-Newton-Marquardt方法求得基元反应的速率常数及活化参数。