Solubility of methane in aqueous solutions of triethylenediamine

The solubilities of methane were measured in water and aqueous solutions of triethylenediamine (TED), triethylenediamine hydrochloride (TED·HCl), and HCl at several concentrations up to 1M at 5° intervals from 5 to 25°C. Methane solubilities in solutions of TED·HCl and HCl are lower than those in water and decrease with increasing cosolute concentration. In contrast, the solubilities in TED solutions are greater than those in water and increase with increasing TED concentration. The order of methane solubilities at 25°C in water and in 0.5M aqueous solutions is TED>H₂O>HCl>TED·HCl with Ostwald coefficients of 3.57×10^–2, 3.44×10^–2, 3.26×10^–2, and 3.19×10^–2, respectively, and with an experimental precision of about ±0.2×10^–3. Thermodynamic functions for the transfer of methane from water to 0.25, 0.50, and 0.75M aqueous solutions have been calculated on the molar concentration scale. The free energies of transfer are compared with previous results for methane in aqueous solutions of tetraalkylammonium halides.     

Two highly porous single-crystalline zirconium-based metal-organic frameworks

Herein we report two highly porous Zr-based metal-organic frameworks(MOFs, 1 and 2) constructed by the truncated octahedral secondary building unit(SBU) of Zr_6O_4(OH)_4(CO_2)_(12) and the organic linear ligand of 4,4.-stilbenedicarboxylic acid(H_2sbdc) or4,4′-azobenezenedicarboxylic acid(H_2abdc). Both Zr-based MOFs are obtained as single crystals of suitable size for single-crystal X-ray diffraction analysis. Furthermore, these two Zr-based MOFs have been fully characterized by powder X-ray diffraction(PXRD) studies, thermogravimetric analysis(TGA), infrared spectroscopy(IR) and gas adsorption analysis. In particular, their CO_2 gas adsorption behaviors have been investigated and discussed.     

基于相关光子多模式相关性的InSb模拟探测器定标方法

利用基于参量下转换产生的相关光子可以实现“无溯源”的绝对定标. 将该方法推广应用于模拟探测器定标的过程中, 获取两路模拟光电流信号的有效相关信息是主要难点. 在相关光子的多模式相关性理论模型的基础上, 提出了一种新的光电流处理方案. 通过将某一时刻采集到的光电流所包含的电荷量转换为等效光子计数, 采用双光路平衡探测和双通道数据波动校正的技术思路, 开展了红外模拟探测器量子效率定标验证实验研究. 利用532 nm单波长激光器为抽运源、PPLN晶体为非线性晶体, 在25 ℃工作温度下获取了631和3390 nm的相关光子对, 定标了InSb红外模拟探测器在3390 nm处的绝对功率响应度. 结果表明, 对InSb模拟探测器的合成不确定度为7.785%. 根据量子效率与绝对功率响应度之间的函数关系, 定标结果与国内计量单位的校准结果的相对偏差为3.6%. 利用多模式相关性在模拟信号下实现红外模拟探测器的绝对功率响应度定标在国际上暂无此方面的报道, 该方法验证了应用多模式相关性理论开展模拟探测器定标方法的可行性, 对于探索基于相关光子的定标技术和拓宽辐射定标应用领域具有重要意义.     

Aqueous solutions of azoniaspiroalkane halides. VI. Apparent molal volumes and apparent molal heat capacities of chlorides and iodides

Densities and heat capacities of aqueous solutions of azoniaspiroalkane halides, (CH₂) _n N⁺ (CH₂) _n X^– (where X=Cl, I andn=5,6), have been measured at 25°C using a flow densimeter and a flow microcalorimeter. The limiting apparent molal volumes (ø _v ) and apparent molal heat capacities (ø _cp ) obtained from these data are compared with those of the azoniaspiroalkane bromides and the corresponding tetraalkylammonium halides. The concentration dependence of ø _v and ø_cp are examined for clues on the influence of solute hydration, structure, and conformational flexibility on the excess functions of quaternary ammonium halides.     

Thermodynamics of some perfluorocarbon gases in water

The solubilities of CF₄ and C₂F₆ gases in H₂O and D₂O in the temperature range of 5 to 30°C at 5° intervals and C₃F₈ and c-C₄F₈ gases in H₂O over the temperature ranges of 5 to 15°C and 5 to 30°C, respectively, have been determined. From the solubility data various thermodynamic quantities for the process of dissolution have been derived. These data were compared with our results of applying the scaled-particle theory to gain an insight into the various thermodynamic processes accompanying the gas dissolution. One of our conclusions is that the hydrophobicity of the perfluorocarbons is greater than that of the corresponding alkanes.     

关于利巴韦林熔点的研究

详细探讨了利巴韦林制备过程中的催化剂以及氨解工艺,并对以往文献做出的结论提出了异议,试验证明:高熔点(174-176C)的物质是由于缩合物氨解不彻底造成的并且与低熔点(166-168℃)的利巴韦林组成不相同.这两种物质不可互相转换.     

In Operando Analysis of Diffusion in Porous Metal-Organic Framework Catalysts

The potential to exert atomistic control over the structure of site-isolated catalyst sites, as well as the topology and chemical environment of interstitial pore spaces, has inspired efforts to apply porous metal-organic frameworks (MOFs) as catalysts for fine chemical synthesis. In analogy to enzyme-catalyzed reactions, MOF catalysts have been proposed as platforms in which substrate confinement could be used to achieve chemo- and stereoselectivities that are orthogonal to solution-phase catalysts. In order to leverage the tunable pore topology of MOFs to impact catalyst selectivity, catalysis must proceed at interstitial catalyst sites, rather than at solvent-exposed interfacial sites. This Minireview addresses challenges inherent to interstitial MOF catalysis by 1) describing the diffusional processes available to sorbates in porous materials, 2) discussing critical factors that impact the diffusion rate of substrates in porous materials, and 3) presenting in operando experimental strategies to assess the relative rates of substrate diffusion and catalyst turnover in MOF catalysis. It is anticipated that the continued development of in operando tools to evaluate substrate diffusion in porous catalysts will advance the application of these materials in fine chemical synthesis.     

A nuclear magnetic resonance study of toluene-polyisobutylene solutions. 3. Spin-lattice relaxation: Rotational and segmental motion

The spin-lattice relaxation times are determined for the methylene carbon of polyisobutylene (PIB), as well as for the ortho carbon of toluene in toluene-polyisobutylene solutions. The Hall-Helfand correlation function combined with restricted anisotropic rotational diffusion was used to treat the T₁ data of the methylene carbon of PIB. A simple exponential correlation function was used to describe the local motion of toluene in the solutions which falls in the extreme narrowing limit for the solutions studied. Both models described satisfactorily the temperature and field dependence of the spin-lattice relation times. From the temperature dependence of the correlation times for the polymer segmental motion, the free volume of the solution at each concentration is extracted and compared with the values obtained from previous studies of the translational motion of the toluene penetrant. The free volume values extracted from the T₁ data for the methylene carbon of PIB and the self-diffusion data for the toluene were found to be in substantial agreement. The interrelationship of the timescale of segmental motion of the polymer and the translational diffusion of the toluene was also examined and it was found that the two types of motion seem to be correlated in high polymer concentrated solutions. The toluene reorientational motion was found to be much faster than both the polymer segmental motion and the toluene translational diffusion leading to the conclusion that the toluene reorientational motion is uncoupled from these two motions. ©1995 John Wiley & Sons, Inc.