Bioinspired manganese complexes catalyzed epoxidation for the synthesis of the epoxyketone fragment of carfilzomib

We report herein an efficient catalytic epoxidation reaction for the synthesis of epoxyketone (tert-butyl ((S)-4-methyl-1-((R)-2-methyloxiran-2-yl)-1-oxopentan-2-yl)carbamate), which is an important synthetic intermediate of carfilzomib.     

SYNTHESIS OF MESOPOROUS POLY(STYRENE-co-MALEIC ANHYDRIDE)/SILICA HYBRID MATERIALS VIA A NONSURFACTANT-TEMPLATED SOL-GEL PROCESS*

Mesoporous poly (styrene-co-maleic anhydride)/silica hybrid materials have been prepared. The synthesis wasachieved by the HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and styrene-maleic anhydride copolymerin the presence of 3-aminopropyl triethoxysilane (APTES) as a coupling agent and citric acid as a nonsurfactant template orpore-forming agent, followed by ethanol extraction. Characterization results from nitrogen sorption isotherms and powder X-ray diffraction indicate that polymer-modified mesoporous materials with large specific surface areas (e.g. 900 m~2/g) andpore volumes (e.g. 0.6 cm~3/g) could be prepared. As the citric acid concentration is increased, the specific surface areas, porevolumes and pore diameters of the hybrid materials increase.     

The evolution of morphology of ordered porous TiO2 films fabricated from sol-gel method assisted ZnO nanorod template

Ordered porous TiO₂ films, including TiO₂ nanotube arrays, are fabricated by a sol-gel dip-coating approach via ZnO nanorod templates obtained from aqueous solution approach. The results indicate that the morphologies of ordered porous TiO₂ films have been great affected by the sol-gel dip-coating cycle number. Open-ended TiO₂ nanotube arrays can be obtained in optimum dip-coating cycle numbers. The TiO₂ nanotubes with the inner diameter matching well with the diameters of ZnO nanorods, are well assembled and separate each other. When the cycle number is less than this optimum value, no intact porous TiO₂ film can be obtained. As the cycle number is larger than this optimum value, an ordered porous TiO₂ film with many throughout holes is formed. The evolutive mechanism of ordered porous TiO₂ films is proposed.     

三溴偶氮胂催化光度法测定痕量铁

本文研究了硫酸介质中痕量 Fe(Ⅲ)催化加速抗坏血酸、溴酸钾和三溴偶氮胂之间的褪色反应及动力学条件,建立了动力学光度法测定痕量Fe(Ⅲ)的新方法.方法灵敏度为1.82×10~(-12)g·ml~(-1).测定范围为Fe(Ⅲ)0～30ng/25ml.已用于人发和食品中痕量铁的测定.结果满意.     

Synthesis of alpha-MoTe2 nanorods via annealing Te-seeded amorphous MoTe2 particles

Semiconductor alpha-MoTe2 nanorods have been synthesized by annealing Te-seeded particles of an amorphous MoTe2 intermediate. This intermediate is prepared by a solution reaction between Mo(CO)6 and elemental Te in diphenylmethane. The as-synthesized products were characterized by structural, compositional, and morphological techniques of X-ray diffraction, selected area electron diffraction, selected area energy dispersive spectroscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The results of the annealing process are MoTe2 nanorods with diameters of 50-200 nm and lengths ranging from 0.1 to 3.0 microm. Here, the rodlike structure of MoTe2 is reported for the first time, and added to the list as one kind of new morphology of MoTe2 nanomaterials. A mechanism for the formation of the nanorods is proposed. The sandwich-layered structure of Te-Mo-Te and the similarity in the structure between hexagonal alpha-MoTe2 and hexagonal Te are responsible for the formation of nanorods of MoTe2.     

羧酸铜催化反应的研究——Ⅰ.羧酸铜催化醛肟转变为睛

本文报道了在多种羧酸铜催化下,醛肟在含有氰基的溶剂中(如CH_3CN、CH_3OCH_2CH_2CN等),均可脱水转变成相应的腈。反应条件温和,产率较高。具有不同空间和电性效应取代基的羧酸铜对反应的产率影响不大。实验中还发现溶剂乙腈参与了上述反应。     

甲基丙烯酸羟烷基酯与丙烯腈或丙烯酰胺共聚合的研究

测定了亲水性甲基丙烯酸羟烷基酯如HEMA、MHPMA分别与AN或AAM,在60℃不同溶剂中自由基聚合反应的竞聚率。AN(M_1)-HEMA(M_2)共单体,在DMSO或DMF溶剂以AIBN或KPS-IPA引发剂条件下共聚,用Kelen-Tüds法计算的竞聚率变化不大,r_1=0.22-0.25、r_2=0.97-1.05,说明在此均相溶液共聚中,所用的溶剂及引发剂对竞聚率的影响较小,这两种单体能很好共聚。但AAM-MHPMA或AAM-HEMA共单体时,r_1与r_2值相差很大,如前者r_1=0.0433、r_2=3.98,后者r_1=0.0535、r_2=1.89,说明不易共聚,共聚物中主要是MHPMA或HEMA组分。     

A new two‐dimensional CdII coordination polymer constructed by pyrazine‐2,3‐dicarboxyl­ate

In the title compound, poly[μ₅‐pyrazine‐2,3‐dicarboxyl­ato‐cadmium(II)], [Cd(C₆H₂N₂O₄)]_n or [Cd(pdc)]_n, where pdc is the pyrazine‐2,3‐dicarboxyl­ate anion, the Cd^II atom is six‐coordinated by five carboxyl­ate O atoms and one N atom from five different pdc ligands in a distorted octa­hedral CdO₅N coordination geometry. Two Cd^II atoms are bridged by carboxyl­ate groups of the pdc ligands to create a dimeric unit. The dimeric units are further connected by the pdc ligands to generate an inter­esting two‐dimensional structure.     

Fine structures of zeolite-Linde-L (LTL): surface structures, growth unit and defects

High-resolution electron microscopy (HREM) has been used to image the surface structure of nano- and micrometer-sized synthetic crystals of zeolite-Linde-L (LTL). Columnar holes and rotational, nano-sized, wheel-like defects were observed within the crystals, where the hole has a minimum size equal to that of the rotational defect. Predictions of surface structure from atomistic computer simulation concur with the observations from HREM and provide insight into the crystal growth mechanism of perfect and defective LTL. Analysis of the energetics of the formation of rotational defect structures reveals that the driving force for defect creation is thermodynamic and furthermore, the rotational defects could be created in high concentrations. Formation of a columnar hole is found to be slightly energetically unfavourable and therefore we speculate that the incidence of both rotational and nano-sized vacancy defects is strongly dependent on kinetic factors and reaction conditions. The morphology of nano- and microcrystalline LTL is contradistinct and we use insights from simulation to propose an explanation of the disparity in crystal shape.     

Analysis of guanidine in high salt and protein matrices by cation-exchange chromatography and UV detection

A simple and sensitive HPLC method for quantitative determination of guanidine in high salt and protein matrices was developed. The HPLC system consisted of an Agilent 1100 pump with an online degasser, a UV detector, an autosampler, and Dionex CS 14 cation-exchange guard (4 mm x 50 mm) and analytical (4 mm x 250 mm) columns. The mobile phase was 3.75 mM methanesulfonic acid (MSA) with a flow rate of 1 mL/min. The other analysis parameters were: 50 microL injection volume, 195 nm UV detection, and 21 min runtime. The limit of quantitation (LOQ) for guanidine HCl was determined to be 0.25 mg/L and the standard curve ranged from 0.25 mg/L to 10 mg/L. Sample preparation was required for the samples containing high protein concentrations. Proteins were removed by centrifuging a sample in a 30 K NanoSep centrifugal filter at 15,300 x g for 20 min. The method could determine guanidine accurately in sample matrices containing up to 200 mM sodium ion or up to 50 mM potassium ion. The method can be used for clearance testing of guanidine in biopharmaceutical products.