Novel Route for Preparation of 7‐Methyl‐camptothecin and Its Possible Mechanism

A novel route for preparation of 7‐methyl‐camptothecin is described. Its possible mechanism is discussed.     

Chemoenzymatic Route to S-Betaxolol

An efficient chemoenzymatic route to S-betaxolol is reported. A strain (Rhodotorula mucilaginosa DQ832198) screened from soil was used as biocatalyst for the kinetic resolution of the key acetylated intermediates. Excellent enantiomeric excess (ee > 99%) was obtained under very mild conditions. The biocatalyst is quite stable and could be used several times with little decrease of the resolving ability.

丙烯腈废水中有机物的高压放电法降解机理

利用气相色谱-质谱探讨了丙烯腈废水中有机物的高压放电法降解机理.结果表明:丙烯腈的氰基首先被破坏生成丙烯酸,丙烯酸进一步被氧化生成乙酸,乙酸降解为甲酸,最后生成CO2.丁二腈首先降解为丁二酸,丁二酸再生成丙酸,并逐步降解为乙酸、甲酸,最后生成CO2.二氰乙基胺在降解过程中依次生成丙腈、丙酸、乙酸和甲酸,最后生成CO2....     

Study on deactivation and regeneration of Pd/Al2O3 catalyst in hydrogen peroxide production by the anthraquinone process

Deactivated palladium catalysts in the hydrogenation of anthraquinione were regenerated with ethanol, nitric acid, hydrogen peroxide, boiling water and steam, respectively. The deactivated and regenerated catalysts were characterized by XPS, ICP, TG, FTIR, TPD, XRD, etc., and studied in the hydrogenation of anthraquinone. The results showed that the main cause of catalyst deactivation is the coverage of the active component by deposits. The treatments by hydrogen peroxide and boiling water can effectively regenerate the deactivated catalysts. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis,Crystal Structure and Properties of Na2MnO2

Na₂MnO₂ was prepared via the azide/nitrate route. Stoichiometric mixtures of the precursors (Mn₂O₃, NaN₃ and NaNO₃) were heated in an appropriate regime up to 390 °C and annealed at this temperature for 20 h, in specially designed silver containers. As the most prominent feature, the crystal structure of Na₂MnO₂ (C2/c, Z = 12, a = 12.5026(9), b = 12.1006(9), c = 6.0939(4) Å, β = 117.94(0)°, 1556 independent reflections, R₁ = 3.83 % (all data)) forms a three dimensional framework polyanion of corner sharing MnO₄‐tetrahedra. The connectivity pattern of the tetrahedral building units corresponds to the moganite structure, a rare SiO₂ modification. According to measurements of the magnetic susceptibility in the temperature range from 2 to 750 K, Na₂MnO₂ shows antiferromagnetic ordering below 250 K. Evaluation of the high temperature data employing the Curie‐Weiss law revealed a magnetic moment of μ_eff = 5.93 μ_B, confirming the presence of divalent manganese.     

A New Orthorhombic Phase of ZrW1.6Mo0.4O8 at Ambient Pressure

IntroductionZr W2 O8presents a few models of structures.The first report was made by Graham etal.[1] andconfirmed by Chang et al.[2 ] in the pseudobinaryphase diagram of a Zr O2 - WO3 system atatmospheric pressure.Cubic zirconium tungstate,Zr W2 O8,possesses the acentric P2 13 structure( αform,a=0 .91 5 75 nm at 2 93K) [3 ] and istransformed to the disordered centric Pa3structure(β form,a =0 .91 371 nm,at 483 K) [3 ] .Theprecise transition temperature ofα toβ form is448K determined …     

Living Polymerization via Anionic Initiation for the Synthesis of Well‐Defined PPV Materials

The anionic polymerization of PPV via the sulfinyl precursor route is further investigated. When LHMDS is employed as the base to form the actively propagating quinodimethane system and THF as the solvent, anionic polymerizations can be observed. With the use of tert‐ butyl‐substituted anionic initiators, specific functional groups can be built in the polymer chain and the chain length can be efficiently controlled, which is demonstrated here for the first time. With introduction of branched side chains on the aromatic core, soluble conjugated PPV material can be obtained with molecular weights in the range of 5000–16 000 g mol⁻¹.     

铂修饰的{001}面暴露的二氧化钛纳米片阵列的制备和光催化性能

采用有机溶剂热法在FTO衬底上制备{001}面暴露的单晶锐钛矿相TiO2纳米片阵列,通过FESEM和XRD研究样品的形貌和晶体结构. 与水热法制备的纳米片阵列相比,有机溶剂热法制备的样品取向性更好. 采用光沉积方法在纳米片阵列上沉积Pt,所得到的Pt纳米颗粒粒径更为均匀,并且更容易沉积在{001}面上. 所负载的Pt 纳米颗粒增强了TiO2纳米片的光吸收性能,同时大大减弱了光致发光强度. 在光催化性能测试中,具有最优负载量的样品催化性能提高了一倍. 与传统的Pt负载相比,{001}面的最优负载量显得相当小,这可能源于高活性{001}面的原子结构.     

{110}晶面取向Ag3PO4多面体的水热制备及可见光催化活性

采用简易水热法在聚乙二醇-6000 (PEG-6000)辅助下合成了Ag₃PO₄多面体.系统考察了水热反应温度、时间及PEG-6000用量对产物形貌和结构的影响.通过X射线衍射(XRD),扫描电子显微镜(SEM),紫外-可见漫反射光谱(UV-Vis DRS)和荧光(PL)光谱等测试手段对光催化剂进行了表征.结果表明,适宜的水热温度及PEG-6000用量是制备具有{110}活性晶面取向Ag₃PO₄多面体的必要条件,该多面体通过纳米颗粒的Ostwald熟化效应生长而成.可见光催化降解罗丹明B (RhB)的实验表明,该Ag₃PO₄多面体活性明显优于其它水热条件下所制备的非{110}取向晶面样品和离子交换法所得纳米颗粒,其降解反应速率常数(k)为离子交换法所得Ag₃PO₄纳米颗粒的8.3倍.总有机碳含量(TOC)及循环实验证明,该Ag₃PO₄多面体可以有效地矿化RhB并保持较好的循环稳定性.活性自由基捕获实验表明,空穴(h⁺)和羟基自由基(·OH)是光催化氧化的主要活性物种.结合活性物种的氧化还原电位以及Ag₃PO₄的能带结构分析,提出了催化反应界面光生电子-空穴(e^--h⁺)对的分离及转移机制.     

High‐performance segmented polyurea by transesterification of diphenyl carbonates with aliphatic diamines

In an effort to develop a green process for the production of elastomeric polyurethane–urea (PUaE) through a nonisocyanate route, a highly practical method was found using diphenyl carbonate (DPC) instead of diisocyanate as the carbonylation agent. The transesterification of aliphatic diamines in a solvent such as tetramethylene sulfone (TMS) with DPC results in a new process obtaining new segmented PUaE with high molecular weights and excellent mechanical performance. The key to the present success lies in the timing and sequence of the diamine addition forming initial carbamate intermediates in situ and then in shifting the equilibrium toward polyurea product formation by phenol removal from the TMS solution so that high‐molecular‐weight polyurea could be formed favorably. The most optimized polyurea films made in this study has a η_inh of 0.64, with high‐performance characteristics showing tensile strength of greater than 30 MPa and elongation exceeding 400% with decomposition temperature (5%) of >280 °C. Well‐defined soft‐ and hard‐segment domains were observed for the products as determined by atomic force microscope. This new improved process to produce segmented polyurea thereby complies fully with the principles of green chemistry using readily available chemicals. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2781–2790