矿物药金礞石的红外光谱分析

采用傅立叶红外光谱法分析了金礞石试样,对所得图谱进行解析,发现试样的红外光谱具备层状硅酸盐矿物的吸收特征.其吸收带主要分为4个区域:3 700～3 000 cm-1区间的OH伸缩振动吸收,1 620 cm-1左右处的H2O弯曲振动吸收,1 000 cm-1左右处的Si-O伸缩振动吸收和550～400 cm-1区间的Si...     

Enantioselective separation of the carfentrazone‐ethyl enantiomers in soil,water and wheat by HPLC

A simple enantioselective HPLC method was developed for measuring carfentrazone‐ethyl enantiomers. The separation and determination was accomplished on an amylose tris[(S)‐α‐methylbenzylcarbamate] (Chiralpak AS) column using n‐hexane/ethanol (98:2, v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 248 nm. The effects of mobile‐phase composition and column temperature on the enantioseparation were discussed. The accuracy, precision, linearity, LODs, and LOQ of the method were also investigated. LOD was 0.001 mg/kg in water, 0.015 mg/kg in soil and wheat, with an LOQ of 0.0025 mg/kg in water and 0.05 mg/kg in soil and wheat for each enantiomer of carfentrazone‐ethyl. SPE was used for the enrichment and cleanup of soil, water, and wheat samples. Recoveries for two enantiomers were 88.4–106.7% with RSD_r of 4.2–9.8% at 0.1, 0.5, and 1 mg/kg levels from soil, 85.8–99.5% with the RSD_r of 4.4?9.6% at 0.005, 0.025, and 0.05 mg/kg levels from water, and from wheat the recoveries were 86.3?91.3% with RSD_r below 5.0% at 0.2, 0.5, and 1 mg/kg levels. This method could be used to identify and quantify the carfentrazone‐ethyl enantiomers in food and environment.     

A mild and efficient rhenium-catalyzed transfer hydrogenation of terminal olefins using alcoholysis of amine-borane adducts as a reducing system

[ReBr₂(NO)(CH₃CN)(PTA)₂] (PTA = 1, 3, 5-triaza-7-phosphaadamantane) catalyzes the alcoholysis of ammonia-borane and amine-boranes and the catalytic transfer hydrogenations of various terminal olefins. Excellent yields were achieved at 70 °C in isopropanol using tBuOK as a co-catalyst affording TOF values up to 396 h⁻¹.     

Ag负载TiO2纳米管微波辅助水热法制备及其光催化性能

以微波辅助水热法制备了二氧化钛纳米管,然后通过浸渍法在其表面负载了银纳米颗粒.所得样品用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、氮吸附、X射线光电子能谱(XPS)、紫外-可见漫反射等测试方法表征.微波加热处理可以大大缩短反应时间,产物为无定型纳米管,经高温焙烧后转变成锐钛矿型二氧化钛.所得纳米管的外径为7-8 nm,内径为5-6 nm,管长约200 nm,比表面积可达371 m2·g-1.负载的银分散在纳米管的表面,对纳米管的结构与晶型没有影响,但是拓宽了二氧化钛的光吸收范围,使吸收边红移至可见光区,并且有效抑制了光生电子空穴的复合.在可见光降解罗丹明B的实验过程中,与Ag负载的P25及纯二氧化钛纳米管相比,Ag负载二氧化钛纳米管具有更高的可见光催化活性,并且当Ag/Ti 物质的量的比为0.5%时,可见光催化性能最好.     

1,1-二(2,4,6-三硝基苯甲酰胺基)-2,2-硝基乙烯的合成

以1,1-二氨基-2,2-二硝基乙烯(FOX-7)和2,4,6-三硝基苯甲酰氯(TNBC)为原料反应合成得到了1,1-二(2,4,6-三硝基苯甲酰胺基)-2,2-二硝基乙烯,并通过单因素试验和正交试验方法,分别探讨了反应介质、缚酸剂、反应温度和反应时间等对产物产率的影响,得到适宜的工艺条件为:FOX-7与TNBC物质的量的比1∶2.4,以四氢呋喃(THF)为反应介质,N,N-二甲基甲酰胺(DMF)为缚酸剂,反应温度0℃,反应时间48 h,产率可达94％.采用紫外可见光谱(UV-Vis)、核磁共振氢谱(1H NMR)、核磁共振碳谱(13C NMR)、红外光谱(FT-IR)、质谱(MS)及元素分析等对产物的结构进行了表征.利用差热分析仪对产物热稳定性进行了研究,结果表明,产物在空气中分解峰值温度为167℃,理论计算爆速为7.434km· s-1,爆压为23.67 GPa.     

金催化CO氧化湿度增强效应的理论研究

实验发现纳米金催化的CO氧化有良好的湿度增强效应,但有关机制仍不清楚.我们应用密度泛函理论研究了湿度增强效应的微观机制,以Au4团簇为例,研究了金催化CO氧化的微观机理,考察了H2O在反应中的角色和作用.计算结果表明,H2O与Au4团簇一样,在反应中扮演催化剂的角色,参与反应的进行、改变反应历程、降低反应能垒.催化循环包含4个基元步骤：O2＋H2O→OOH＋OH,CO＋OOH→CO2＋OH,CO＋OH→COOH,和COOH＋OH→CO2＋H2O,其中自由基OOH和OH的形成是催化循环的速控步骤,其能垒为100.31kJ/mol,明显低于非水参与反应的能垒（161.41kJ/mol）.目前的结果合理地解释了实验观测的CO催化氧化的湿度增强效应,给出了其微观反应机制.     

高效液相色谱法同时测定忍冬中7种成分

建立了在不同时间段内转换使用不同波长同时测定忍冬花和叶中7种化学成分(绿原酸、咖啡酸、芦丁、木犀草苷、异绿原酸A、异绿原酸B、异绿原酸C)的高效液相色谱分析方法,同时应用该方法分析了忍冬花、忍冬老叶和新叶中成分含量的差异。色谱柱为Agilent Eclipse Plus C18(250 mm×4.6 mm, 5 μm);流动相为0.3%甲酸水溶液(A)和乙腈(B),梯度洗脱,流速1 mL/min;采用VWD紫外检测器转换波长(330 nm、350 nm)检测。应用所建立的方法测定忍冬新叶中绿原酸、木犀草苷含量分别为2.572%、1.498‰,均比药典中规定的含量高,有必要进一步的研究和开发利用。该方法准确、简便、灵敏度高,适用于忍冬中7种化学成分含量的同时测定和忍冬的质量控制及综合评价。     

Chemoselective hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol over Ir-MoOx/Si02 catalyst

In this work, MoOx promoted Ir/SiO2 catalysts were prepared and used for the selective hydrogenolysis of tetrahydrofurfuryl alcohol （THFA） to 1,5-pentanediol in a continuous flow reactor. The effects of different noble metals （Ir, Pt, Pd, Ru, Rh）, supports and Ir contents were screened. Among the investigated catalysts, 4 wt%Ir-MoOx/SiO2 with a Mo/Ir atomic ratio of 0.13 exhibited the best catalytic performance. The synergy between Ix particles and the partially reduced isolated MoOx species attached on them is essential for the excellent catalytic performance of Ix-MoOx/SiO2. The catalyst exhibited a better hydrogenolysis efficiency of THFA with the selectivity of 1,5-pentanediol of 65%-74% at a conversion of THFA of 70%-75% when the initial THFA concentration is ranging from 20 wt% and 40 wt%. And higher system pressure was also in favor of the conversion of THFA. During a stability test, the conversion of THFA and 1,5-pentanediol yield over Ix-MoOz/SiO2 decreased with reaction time, which can be explained by the leaching of Mo species during the reaction.     

氮化硅新相P6和P6＇的理论研究：一种研究陶瓷材料的新工具

在原子尺度上构建模型,采用密度泛函理论结合准谐波近似研究了氮化硅新相（P6和P6＇相）的点阵常数、弹性常数和弹性模量. 并使用β-Si3N4作基准材料来测试计算结果的准确性. 研究发现β-Si3N4的晶胞常数和弹性常数与实验值吻合相当好. 研究了P6和P6＇相在30～55 GPa的各向异性因子、脆性和力学稳定性,结果表明两相属于金属性和脆性材料,且晶体的脆性和各向异性都随着压强的升高而增大. β相在40 GPa和300 K时会转变成P6＇相. 当压强继续升高到53．2GPa时,P6＇相又转化成δ相．同时研究了氮化硅的热容、体积和体模量等性质随温度的变化规律．