Palladium complexes bearing an N‐heterocyclic carbene–sulfonamide ligand for cooligomerization of ethylene and polar monomers

Herein, we report the synthesis of palladium complexes bearing an N‐heterocyclic carbene (NHC)‐sulfonamide bidentate ligand and their application in ethylene oligomerization and ethylene/polar monomer cooligomerization. These catalysts could smoothly catalyze ethylene oligomerization and ethylene/methyl acrylate cooligomerization albeit the performance was lower compared to that of a NHC–phenoxide catalyst. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 474–477     

电解质和pH值对毒死蜱微乳液透明温度范围的影响

研究了电解质和pH值对毒死蜱微乳剂透明温度范围的影响,表面活性剂采用特殊苯乙基酚甲醛树脂聚氧乙烯醚和十二烷基苯磺酸钙(DBSCa)(质量比为3:7)复合物,质量分数75%毒死蜱二甲苯溶液为油相。研究结果表明,电解质的加入对表面活性剂作用的微乳剂透明温度范围均有显著影响,使上限温度明显下降;随阳离子电解质质量分数增加,上限温度下降;随阴离子电解质价数增加,上限温度先略增加后下降。电解质及其价数对下限温度影响均不大。弱酸性介质有利于扩大体系的透明温度范围,使上限温度达到最大值;而强酸性和强碱性介质,均使体系的上限温度下降。体系下限温度随pH值的增加缓慢升高。     

Crossover Peng-Robinson equation of state with introduction of a new expression for the crossover function

In this research, we use the original Peng-Robinson (PR) equation of state (EOS) for pure fluids and develop a crossover cubic equation of state which incorporates the scaling laws asymptotically close to the critical point and it is transformed into the original cubic equation of state far away from the critical point. The modified EOS is transformed to ideal gas EOS in the limit of zero density. A new formulation for the crossover function is introduced in this work. The new crossover function ensures more accurate change from the singular behavior of fluids inside the regular classical behavior outside the critical region. The crossover PR (CPR) EOS is applied to describe thermodynamic properties of pure fluids (normal alkanes from methane to n-hexane, carbon dioxide, hydrogen sulfide and R125). It is shown that over wide ranges of state, the CPR EOS yields the thermodynamic properties of fluids with much more accuracy than the original PR EOS. The CPR EOS is then used for mixtures by introducing mixing rules for the pure component parameters. Higher accuracy is observed in comparison with the classical PR EOS in the mixture critical region.     

Semi-empirical insertion probability for hard-spheres and hard-sphere chains

In spite of its simplicity and a well-defined theoretical basis, the Flory–Guggenheim approach is conventionally regarded as inapplicable to off-lattice system since the insertion probability of the approach does not account for the excluded region, existing in the off-lattice system. In this work, we propose the insertion probability accounting for the excluded region of off-lattice fluids and derive a new version of equation of state (EOS) for hard-sphere chains basing on the Flory–Guggenheim approach. To investigate the behavior of the excluded regions, a Monte Carlo sampling was performed for hard disks and the various excluded regions were found to have different density dependence. On the basis of the simulation result, we formulated the insertion probability for hard-sphere and that of hard-sphere chain which accounts for the effect of chain-connectivity on the monomer insertion. The proposed insertion probability was found to correctly predict the simulation data for monomer and correctly correlate the simulation data for chain fluids. The resulting EOS was found to meet closed-packed limit and predict the simulation data of compressibility factor for monomer and chains with a reasonable degree of accuracy. When compared with other off-lattice based EOS, it shows a comparable or better result. For second virial coefficient of chain molecules, the model was found to reasonably predict the simulation data.     

超临界水临界区域判定方法研究

对超临界水在临界区域进行合理的判定和区域划分,对于深入理解超临界水在临界过渡区域的流动和换热相关特征具有重要的作用。本文分析了超临界水从拟液态区向拟汽态区过渡的过程中,其导热系数、动力粘度、定压比热和膨胀系数等相关参数的变化规律特征,并归纳了已有超临界水在临界区域的划分判定模型。分析结果表明,在临界过渡区域,超临界水的流动特征参数和换热特征参数均会发生一系列连续剧烈的变化;只有同时考虑超临界水的膨胀特性和最大比热特性,才能更加合理地对临界区域进行划分。在此分析基础上,本工作完善了超临界水的三区分析判定模型,得到了新的超临界水在临界区域的判定划分数据,并由此拟合得到了新的超临界水分区边界计算关系式。新的计算关系式的误差范围在±0. 3℃之内,满足计算分析的要求。     

P204萃取剂皂化过程中的物理化学性质及相区变化

Ｐ２０４萃取剂皂化过程中的物理化学性质及相区变化曾平,王贵清（湘潭大学化学系,湘潭,４１１１０５）关键词皂化Ｐ２０４萃取剂,物理化学性质,相区,微乳状液二－（２－乙基己基）磷酸（简称Ｐ２０４或ＨＡ）是一种良好的工业螫合萃取剂,在湿法冶金中得到广泛应用...     

Relative kinetics of the homolytic addition of 2-phenyl-1,3-dioxolane to unsaturated compounds

The CH₂ = CHX olefins form a series relative to their reactivity in reactions with 2-phenyl-1,3-dioxolan-2-yl radicals, which qualitatively correlates with the electron-withdrawing capacity of substituent X: CN CO₂Me >> SiMe₃ C₄H₉. This behavior indicates that the dioxolanyl radical is nucleophilic.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1663–1666, July, 1992.     

On the visco-elastic and dielectric behaviour of two alcohols and their binary mixture

Inter-molecular and intra-molecular interactions in liquids determine the physical properties of the systems. These interactions are understood through the measurement of these physical properties. These become especially important in the case of alcohols in view of the specific type of interactions involved. Study of the variation of dielectric relaxation time with the viscosity of the medium is relevant in drawing certain quantitative conclusions regarding molecular motion and the inter-molecular forces in liquids, liquid mixtures, dilute solutions and multi-component polar solutes in dilute solution. In the absence of a perfect empirical or theoretical equation for the variation of dielectric relaxation time with viscosity, the experimental investigations on different systems can only give an insight. In the present study, the results of dielectric measurements carried out on pure samples of methyl alcohol and propyl alcohol in dilute solutions in different mixed solvents (benzene?+?paraffin) and on binary mixture (1?:?1) of methyl alcohol?+?propyl alcohol are reported. Different parameters determined are presented and these studies indicate that the dielectric behaviour at microwave frequencies favour the concept of dynamic viscosity and a single visco-elastic relaxation time for the systems under study.     

Methods for the synthesis of mono- and polynuclear NH-tetrazoles. (Review)

Data on methods for the synthesis of monocyclic and polynuclear NH-unsubstituted tetrazoles are reviewed.Dedicated to Prof. H. Elguero on the occasion of his 65th birthday.St. Petersburg State Technological Institute (Technical University), St. Petersburg 198013, Russia; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–884, July, 2000.