超声辐射下双吲哚甲烷衍生物的合成

以吲哚、醛为原料,蒙脱土固载路易斯酸为催化剂,超声条件下合成双吲哚甲烷类衍生物。得到最优合成条件为n(吲哚)∶n(醛)=2.0∶1.1,蒙脱土负载氯化铜为催化剂,二氯甲烷作溶剂,反应温度为50℃,超声时间为15 min。产率最高达99.3%,催化剂循环3次产率仍可达81.3%。产物通过核磁、红外、熔点进行表征。     

超临界二氧化碳-烷烃体系相平衡和界面张力的研究进展

超临界二氧化碳(SC-CO2)和烷烃体系的相平衡和界面张力是石油、化工及环境保护等诸多领域中的基础数据。对SC-CO2-烷烃二元体系的相平衡和界面张力的实验测定和理论模型方面的研究进展进行了综述,并分析了同时适用于SC-CO2-烷烃体系的本体和界面性质研究的自洽模型的发展方向。     

取代型N-烷基化反应专利技术综述

N-烷基化反应是合成精细化工中间体的一种重要工艺,其合成方法很多,所得产品可应用于诸多领域。其中,以卤代烷烃、烷基醇、羧酸酯、磺酸酯作为烷基化试剂的取代N-烷基化反应是非常有用的反应类型,也是近期专利申请的热点课题之一。本文对取代型N-烷基化反应专利技术进行了概述。     

烷烃结构异构数新的计算方法

设W_n、Q_n和X_n分别表示n-碳烷(C_nH_(2n n2)n-碳炔(C_nH_(2n-2))和n-碳烯(C_nH_(2n))的同分异构体数,作者发现了下列公式: W_n=Q_(n 2) (1-(-1)~n)/2Q_(n 3)/2-X_(n 1)并算出W_(40)=62,481,801,147,341。(Henze和Blair算出W_(40)=62,491,178,805,831)和W_(50)=1,117,743,651,746,953,270     

Thermal Conductivity Modeling of Refrigerant Mixtures in a Three-Parameter Corresponding States Format

A predictive model for the thermal conductivity (TC), in a corresponding states (CS) format, is proposed here for mixtures of homologous fluids such as the halogenated alkanes (HA) and the alkanes (A), most of which are used as refrigerants. The predictive nature of the model originates from a new study carried out for the TC of pure fluids. For the dilute-gas term the model requires an individual correlation for each component, whereas for the excess contribution the model structure makes use of TC dedicated equations (TCDEs) of two reference fluids, which in this work are methane and R134a. The mixture model adopts specific mixing rules for each of the two TC contribution terms: the dilute-gas term _0mix is obtained from the Mason and Saxena mixture model, while the excess term _{E mix} is determined from the Wong et al. mixing rules in the one fluid model approach. Setting the mixing rules interaction coefficients to unity, the resulting model presents a completely predictive character. The model has been tested on both liquid and vapor phases of the following systems: R32/R125, R32/R134a, R125/R134a, R404a, and R32/R134/R125. For a total of 1223 experimental points in the liquid phase, the overall AAD is 5.39%, while for a total of 2358 points in the vapor phase, the AAD is 2.62%. These predictive mode performances can then be regarded as particularly satisfactory and are of a level similar to the claimed experimental uncertainty. An improved version of the model is also proposed for modeling azeotropic mixtures. The results reached in this case for a total of 1989 experimental points give an average AAD of 5.30%. Considering both the predictive nature and the simple computational procedure of the model, it significantly enhances the calculations of the TC of mixtures.Paper presented at the Sixteenth European Conference on Thermophysical Properties, September 1–4, 2002, London, United Kingdom.     

Photoluminescence of supported vanadia catalysts: linear correlation between the vanadyl emission wavelength and the isoelectric point of the oxide support

Photoluminescence spectra of vanadium oxide supported on SiO₂, TiO₂, Al₂O₃, K‐doped Al₂O₃, ZnO and MgO were recorded. All the vanadium‐containing solids exhibit room‐temperature luminescence in the 550–700 nm region upon excitation from 250 to 400 nm. Significant spectral shifts of the emission maximum wavelength (λ_phos) depending on the acid/basic nature of the support have been observed. In this way, the higher the isoelectric point (or zero point charge, pzc) of the oxide support, the higher is the λ_phos of the supported vanadia catalysts. The linear relationship between these two properties clearly proves that the characteristics of the oxide support has a direct influence on the phosphorescence, and hence on the electronic states, of the vanadyl group. Kinetic analysis of the luminescence decay of supported catalysts has also been determined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Diffusion of linear paraffins in NaCaA studied by the ZLC method

The zero length column (ZLC) technique has been applied to investigate the kinetics of linear alkanes (n-hexane to n-tetradecane) in a sample of zeolite NaCaA. The diffusivity values are found to be monotonically decreasing with chain length from n-hexane to n-undecane, slightly increasing between n-undecane and n-tridecane, and eventually levelling-off at n-tetradecane. The initial monotonic decreasing trend is similar to previous ZLC studies, although the values are somewhat higher for the heavier alkanes. The values found are reasonably close to PFG-NMR results and have similar qualitative trends, but do not show a marked maximum in comparison to recent neutron spin echo (NSE) results. The difference between the infinite dilution ZLC data and the microscopic techniques can not be ascribed to the intrusion of surface resistances since partial loading experiments provide clear evidence that the measurements are controlled by internal diffusion. The activation energy of linear alkanes in NaCaA lies between 20 and 26 kJ/mol.