Importance of the Debye interaction in organic solutions: Henry's law constants for polar liquids in nonpolar solvents and vice versa

Henry's law constants have been determined for -butyrolactone (BL), ethyl acetate (EA), and 2-methyl-3-pentanol (MEP) in mixtures of iso-octane (ISO) and toluene (TOL), for BL, EA, TOL, and ISO in cinnamaldehyde (CIN) and for TOL and ISO in each other and in BL. From these data and published vapor pressures, the activity coefficients at infinite dilution and the standard molar Gibbs free energy of transfer, G ₂ ⁰ of the solutes from dilute solution in ISO to dilute solution in each solvent medium have been calculated. The different behavior patterns of BL and EA are attributed to differences in their abilities to exist in different conformations possessing different dipole moments. For polar solutes, G ₂ ⁰ decreases with increasing polarizability of the solvent and with increasing dipole moment of the solute, suggesting increased contributions from dipole-induced dipole (Debye) interactions. The sigmoidal plot of G ₂ ⁰ against the change in pair potential energy calculated from the classical expressions suggests that G ₂ ⁰ seriously underestimates the strength of the Debye interactions in comparison with the London interactions.     

微波法制备还原氧化石墨烯负载Pt_3Co纳米合金(英文)

微波辐射法可以在数分钟内将高度分散的Pt3Co合金颗粒负载于还原氧化石墨烯表面上.表征结果发现,与传统的溶剂热法和浸渍法相比,微波法制备的催化剂中贵金属的利用率高,合金颗粒的分布均匀,组成可控,同时氧化石墨烯的再石墨化现象也得到有效地抑制.采用微波法制备的Pt3Co/RGO-MW催化剂在肉桂醛加氢反应中具有较高的活性和和产物选择性.Pt3Co/RGO-MW中每一个Pt原子在70℃的转化频率高达23.8 min-1.     

Fe-Co Alloyed Nanoparticles Catalyzing Efficient Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol in Water

Selective hydrogenation of C=O against the conjugated C=C in cinnamaldehyde (CAL) is indispensable to produce cinnamyl alcohol (COL). Nonetheless, it is challenged by the low selectivity and the need to use organic solvents. Herein, for the first time, we report the use of Fe-Co alloy nanoparticles (NPs) on N-doped carbon support as a selective hydrogenation catalyst to efficiently convert CAL to COL. The resultant catalyst with the optimized Fe/Co ratio of 0.5 can achieve an exceptional COL selectivity of 91.7 % at a CAL conversion of 95.1 % in pure water medium under mild reaction conditions, ranking it the best performed catalyst reported to date. The experimental results confirm that the COL selectivity and CAL conversion efficiency are, respectively promoted by the presence of Fe and Co, while the synergism of the alloyed Fe-Co is the key to concurrently achieve high COL selectivity and CAL conversion efficiency.     

Preparation of polymer-protected Pt/Co bimetallic colloid and its catalytic properties in selective hydrogenation of cinnamaldehyde to cinnamyl alcohol

A polymer-protected Pt/Co bimetallic colloid with a molar ratio of 3:1 has been prepared by a polyol process. Over the above Pt/Co bimetallic colloid catalyst, cinnamaldehyde can be selectively hydrogenated to cinnamyl alcohol with 99.8% selectivity at 96.2% conversion.     

纳米Pd/ZSM-5的原位法制备及催化肉桂醛加氢

采用共沸精镏辅助的原位法成功合成了高度分散的Pd纳米颗粒负载在ZSM-5中(Pd/ZSM-5-IS)分子筛催化剂。通过XRD、TEM、XPS等手段对Pd/ZSM-5-IS的样品进行了表征,并考察反应压力、反应温度、反应时间对肉桂醛加氢催化性能的影响。结果表明:原位法制备的Pd/ZSM-5-IS催化剂比浸渍法制备的Pd/ZSM-5-IM催化剂具有更高的催化稳定性,其主要归因于Pd纳米颗粒进入ZSM-5的晶内介孔有效防止活性位点的损失和聚集。当反应温度为80℃,反应压力为1 MPa,反应时间为3 h时为最佳反应条件,肉桂醛的转化率为87.23%,苯丙醛的选择性为76.68%。     

Selective Synthesis of 1,2‐Diarylpyrrolo[3,4‐b]pyridine‐5,7‐diones via Cyclization Reaction of β‐Enamino Imides with Cinnamaldehydes

The novel 1,2‐diaryl substituted pyrrolo[3,4‐b]pyridine‐5,7‐diones were selectively synthesized in high yields by the base catalyzed cyclization reaction of 3‐arylamino‐1‐methyl‐1H‐pyrrole‐2,5‐diones with cinnamaldehyde and its derivatives in acetonitrile at room temperature. However, when piperidinium trifluoroacetate was employed as catalyst, the reaction afforded a mixture of 1,2‐diaryl and 1,4‐diaryl substituted pyrrolo[3,4‐b]pyridine‐5,7‐diones in comparable yields.     

Pt/MIL-101(Cr)在肉桂醛选择性加氢反应中的催化性能

采用简单易行的浸渍法将Pt纳米粒子负载到MIL-101(Cr)上, 制备了Pt/MIL-101(Cr)催化剂, 并对其在肉桂醛选择性加氢反应的催化性能进行了研究。XRD、N₂吸附、TEM和催化性能的研究结果表明, Pt的负载量对负载于MIL-101(Cr)上Pt纳米粒子的尺寸及所制备催化剂对肉桂醇的选择性有很大影响。低Pt负载量(1.0wt%)的Pt/MIL-101(Cr)较其他MOFs和无机材料在肉桂醛选择性加氢反应中表现出了高的催化性能, 在优化的反应条件下肉桂醛转化率和对肉桂醇的选择性可分别达96.5%和86.2%。Pt/MIL-101(Cr)催化剂具有良好的稳定性。Pt/MIL-101(Cr)所表现出的优良的催化性能同MIL-101(Cr)载体的孔道结构及其表面性质密切相关。     

ZrO4/SiO2-Al2O3催化肉桂醛MPV转移加氢性能

以九水合硝酸铝（Al（NO₃）₃·9H₂O）与正硅酸乙酯（TEOS）为前驱盐,采用溶胶-凝胶法制备一系列不同Al₂O₃含量的SiO₂-Al₂O₃复合氧化物,并通过浸渍硝酸氧锆引入ZrO₂,制备ZrO₂/SiO₂-Al₂O₃复合氧化物催化剂,考察催化剂在肉桂醛（CAL）MPV转移加氢中的催化性能,并结合N₂物理吸附、X射线粉末衍射（XRD）、傅里叶变换红外光谱（FTIR）、NH₃-程度升温脱附（NH₃-TPD）、Py-原位红外（Py-IR）等技术,研究催化剂结构、织构以及表面性质与其催化性能间的构效关系.研究表明,所制备的催化剂均以L酸为主,并含有少量B酸中心,这使得加氢产物以肉桂醇（COL）为主,并含有少量1-苯丙烯-2-丙基醚（CPE）.Al₂O₃含量不仅影响催化剂表面的酸中心数量,而且对催化剂的织构参数有较大影响.随Al₂O₃含量的增加,催化剂表面L酸与B酸中心均有所增加,而孔径则持续变小,这使得催化反应呈现CAL转化率先增加后减少、目标产物COL选择性先稍有减小后有所增加的趋势.在Si/Al比为2时,催化剂具有最优的催化性能,优化反应条件下,CAL转化率达96%,目标产物COL选择性达90%.     

贵金属对钴基催化剂上肉桂醛选择加氢反应的影响

 研究了贵金属改性的Co／γ－Al2O3催化剂上的肉桂醛选择加氢反应．结果表明，通过Pt，Pd和Ru贵金属改性，提高了催化剂的活性，但只有Pt改性的催化剂具有较高的选择性．w（Pt）＜0．5％时，催化剂的活性随着Pt含量的增加呈直线升高，当w（Pt）＝0．5％时，催化剂活性可提高近5倍，但催化剂的选择性变化很小．XRD结果表明，催化剂经还原后，γ－Al2O3上的钴主要为α－Co0．TPR结果表明，Pt的加入提高了Co3O4的还原性能，且Pt含量越高，Co3O4的还原温度越低．XPS结果表明，Pt改性的催化剂样品，其Co3O4大部分被还原为Co0．由于Pt与Co具有协同效应，故Pt改性的Co／γ－Al2O3催化剂既具有较高的活性，又具有很高的选择性．     

桂枝的引药作用机制及其对环丙沙星在小鼠体内分布的影响

研究了桂枝和桂皮醛对环丙沙星在小鼠体内分布的影响,并基于此探讨了桂枝作为引药使用的作用机制.实验中将小鼠分为三组,分别灌胃生理盐水、桂枝(50gkg-1)和桂皮醛(0.25mLkg-1),然后对三组小鼠尾静脉注射环丙沙星(20mgkg-1),并以荧光法测定不同时间点小鼠体内各组织中环丙沙星的浓度.结果显示桂枝、桂皮醛均促进了环丙沙星在四肢的分布,桂枝与桂皮醛组相对于生理盐水组可将环丙沙星在四肢的含量提高约40%~200%,证实了桂枝引药到达肢节的作用.桂枝与桂皮醛组对环丙沙星分布情况的影响没有显著性差异,说明桂皮醛很可能是发挥桂枝引药作用的主要物质.