复合还原剂硼氢化钠/三氯化铁对亚砜的还原

硼氢化钠是一种温和、高选择性的亲核还原剂。一般它只能还原醛、酮和酰氯,而对其它功能团不起作用。因而其应用范围有一定的限制。据文献报道,某些金属卤化物能有效地提高硼氢化钠的还原性能^[1]。复合还原剂硼氢化钠/三氯化铁已应用于将β-二烷基氨基共轭烯酮还原为相应的饱和γ-氨基醇^[2]。本文研究了硼氢化钠/三氯化铁对亚砜的还原反应。     

Radical polymerization in the presence of peroxide and reducing agent monomer for branched polymers

In this article, we report the radical polymerization in the presence of peroxide and commercially available or designed reducing agent monomer (RAM) for the preparation of branched poly(methyl methacrylate)s (PMMAs). The reaction behavior of the RAM was studied by NMR. Triple‐detection SEC (TD‐SEC) analysis was used to confirm the branching structure of the prepared PMMAs and to investigate the influence of peroxide concentration and RAM concentration on molecular weight and branched structure. The obtained branched PMMAs exhibited high molecular weights and relatively narrow polydispersities at high conversion of MMA. Interestingly, a significant increase in molecular weight and degree of branching of the obtained polymers are observed in higher BPO concentration, these results are quite different from that reported in the literature. The unique radical polymerization mechanism in the RAM/BPO redox‐initiated radical polymerization system resulted in branched PMMAs with high molecular weights at relatively high RAM and BPO concentrations. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 833–840     

金属纳米颗粒制备中的还原剂与修饰剂

金属纳米颗粒由于其独特的光学、电学、化学性质以及各种潜在的应用价值,受到不少研究人员的广泛关注。实现金属纳米粒子尺寸、形貌可控,改善粒子分散性和稳定性,提高产率及纯度已成为具有挑战性的研究课题,不断发展和完善金属纳米粒子的合成方法则显得尤为重要。本文总结了目前制备金属纳米材料的几种化学方法：化学试剂还原法、电化学还原法、辐射还原法等,分类介绍了化学试剂还原法中常用的无机、有机还原剂,以及含氮、磷、羧基、巯基小分子有机化合物以及高分子聚合物等修饰剂并重点总结了其还原和修饰机理。     

硫代亚磷酸酯抗磨添加剂的合成与应用

通过改性抗磨添加剂亚磷酸二正丁酯 (T3 0 4)合成了新型含磷润滑油抗磨添加剂———硫代亚磷酸O ,O 二 (十二烷基 )酯 (T3 1 1 ) ,其结构经元素分析和HPLC MS确认。T3 1 1与T3 0 4相比热氧化稳定性及耐久性有明显提高。T3 1 1应用于卡车及公共汽车手动变速箱齿轮油中通过了FZG齿轮机试验、L 60 1热氧化稳定性台架试验及Mack变速箱循环台架试验。     

High efficiency of Mn–Ce‐modified TiO2 catalysts for the low‐temperature oxidation of Hg0 under a reducing atmosphere

Manganese‐ and cerium oxide‐modified titania catalysts were prepared by the deposition precipitation for the removal of elemental mercury (Hg⁰) from simulated yellow phosphorus off‐gas at low temperature. In addition, these catalysts were characterized by X‐ray diffraction, Brunauer–Emmett–Teller measurements, X‐ray photoelectron spectroscopy and field‐emission scanning electron microscope to determine the surface morphology of the obtained compounds and explore their formation mechanism. The results revealed that a Mn–Ce loading and reaction temperature of 10% and 150 °C, respectively, as well as a Mn/Ce molar ratio of 2:1, led to an optimal efficiency for the oxidation of elemental mercury. Furthermore, the effects of flue gas components were investigated. The presence of O₂ clearly promoted the oxidation of Hg⁰. A CO atmosphere did not affect the Hg⁰ oxidation, when compared with N₂, whereas the presence of H₂S and water vapor inhibited the oxidation process. Furthermore, the X‐ray photoelectron spectroscopy spectra of Hg 4f revealed that the elemental mercury adsorbed by the catalyst is present as HgO. Finally, the Hg⁰ catalytic oxidation mechanism was discussed on the basis of the experimental results and characterization analysis.     

离子液体降低FCC汽油烯烃体积分数的研究

向FCC汽油中分别加入两种与FCC汽油不互溶的Lewis超强酸性离子液体\[Bmim\]Cl-AlCl3 和 \[R4N\]Cl-AlCl3形成液-液两相催化降烯烃体系。结果表明：在汽油辛烷值基本保持不变的基础上,FCC汽油的烯烃体积分数分别下降14.7%和13.1%, 均达到我国新配方汽油规定的烯烃体积分数v<35%的新标准。对离子液体降低FCC汽油的机理及影响因素进行了详细研究。结果表明,正是由于具备Lewis超强酸性的离子液体催化的烯烃与烷烃的烷基化、烯烃与芳烃的烷基化以及烯烃的二聚反应使得FCC汽油中烯烃体积分数显著下降。     

Use of isothermal microcalorimetry in pharmaceutical preformulation studies

Excipient compatibility of a new chemical entity was assessed using an isothermal microcalorimeter. Mixtures of an active pharmaceutical ingredient with a primary amine group and excipients were prepared in a 1:1 ratio and compatibility monitored by exposing to 50, 60 and 70°C in presence of 200 mL of water. The new chemical entity, a primary amine, reacted with reducing sugars such as lactose and resulted in a brown discoloration. This reaction is the Maillard type condensation reaction between amines and reducing sugars. The rate of reaction was dependent on the temperature with rapid degradation at higher temperatures. No other incompatibility was apparent between the primary amine and other excipients This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparison of the sensitivity of 11 crosslinked hyaluronic acid gels to bovine testis hyaluronidase

Crosslinked hyaluronan gels are used in various applications where their stability is a prerequisite. The sensitivity of such gels to hyaluronidase can be determined as an index of stability by several approaches: chromatography, electrophoresis, and viscometry. We describe here a test based on the colorimetric determination of the N-acetyl-d-glucosamine released by hyaluronidase in standardized conditions. The sensitivities to bovine testicular hyaluronidase of 11 different gels used to fill skin wrinkles (Restylane; Perlane; Juvéderm 18, 24, 24HV, 30, and 30HV; Surgiderm 18, 24XP, 30, and 30XP) were compared.The method was reproducible, easy to perform, not time-consuming and allowed us to demonstrate that the sensitivity to testicular hyaluronidase was dependent on the degree of crosslinking of the gels and also on their monophasic/biphasic nature. Under our conditions, Surgiderm 30, 24XP and 30XP were the most resistant gels.We propose to retain the hyaluronidase test to predict the in situ stability of a crosslinked gel used to fill skin wrinkles.     

Comparative evaluation of Fe(III) reducing power-based antioxidant capacity assays in the presence of phenanthroline, batho-phenanthroline, tripyridyltriazine (FRAP), and ferricyanide reagents

The chemical diversity of antioxidants in complex matrices such as plant extracts makes it difficult to separate and quantify antioxidants from these solutions. Therefore it is desirable to establish methods that can measure the total antioxidant capacity (TAC) levels directly from plant extracts. Iron(III)-based TAC assays, especially the most widely used FRAP (ferric-reducing antioxidant power), play an important role in this regard. However, many problems have been reported in the application of the FRAP assay, the most serious one being the incomplete oxidation of a number of antioxidants during the time protocol of the assay. Thus, six different ferric ion-based total antioxidant capacity (TAC) assays have been comparatively tested, modified, and improved so as to obtain more sensitive and precise results for complex mixtures, namely: 1,10-phenanthroline (o-phen) method (with incubation), batho-phenanthroline method (with incubation), original FRAP method, modified FRAP method (with incubation), original ferricyanide method, and modified ferricyanide method (with incubation). Two new assays in this regard (i.e., o-phen and batho-phen) have been established, and the existing assays (FRAP and ferricyanide) have been modified so as to let the oxidation reactions of antioxidants reach completion. The molar absorptivity for a variety of antioxidants was highest for modified FRAP, batho-phen, and original FRAP methods. The absorption maximum wavelength shifted batochromically to a higher extent for modified ferricyanide, FRAP, and batho-phen procedures, decreasing the possibility of interferences due to organics absorbing in the near-UV range of the visible spectrum where most antioxidant assays are performed. The linear concentration ranges were shown to be further extended and linear correlation coefficients improved with respect to the most widely used ferric-based assay, FRAP. Of the six assays tested and developed, only the modified ferricyanide procedure gave high intercept values and low addivitity of TAC values of constituents in complex mixtures, requiring further attention of method optimization. Thus, it was shown that the most widely used FRAP could be effectively modified, and o-phen, batho-phen, and ferricyanide methods constitute cheaper alternatives to FRAP under certain conditions, with partly improved molar absorptivity (and thus sensitivity) for antioxidants, lower intercept values (and higher precision), broader linear range (and higher flexibility), and better additivity of TAC values of antioxidant constituents in mixtures.     

交联-羧甲基复合变性淀粉的流变与降失水性能

以马铃薯淀粉和氯乙酸为主要原料,通过交联-醚化制备了交联-羧甲基复合变性淀粉(CCMS),考察了所得CCMS糊液的流变性能和在钻井泥浆中的降滤失水性能,并对其降失水原理进行了探讨。结果表明,在质量分数为0.5%~4.0%、温度为20~60℃的实验条件下,CCMS糊液表现为假塑性流体特征,符合Ostwald-Dewaele的经验公式ηa=Kγn-1;将CCMS与中粘羧甲基纤维素(MV-CMC)进行对比实验,结果发现,在饱和盐水泥浆和4%盐水泥浆中,当其用量分别为MV-CMC质量分数的57%和75%时,就可达到钻井液用MV-CMC的增粘、降滤失水性能指标。