劣质汽柴油混合加氢催化剂的研究

收集了国内几种汽柴油混合加氢催化剂,对它们的物理性质进行了分析,并对其加氢活性进行了评价,比较了FH-98催化剂、FH-DS催化剂、FH-UDS催化剂、LYT-UDS催化剂和LYT-03催化剂对劣质汽柴油的加氢活性。结果表明:评价的几种催化剂中,在反应条件为:340℃、6.5 MPa、500∶1及1.5 h-1时,LYT-03催化剂对于劣质汽柴油混合加氢的反应活性最高,脱硫率可达96.08%,脱氮率为93.38%。     

Copolymerization of Methyl Methacrylate,Ethyl Acrylate,and Butyl Acrylate with N-2-Anisylmaleimide and Characterization of the Copolymers

The free radical copolymerizations of methyl methacrylate (MMA), ethyl acrylate (EA), and butyl acrylate (BA) with N-2-Anisylmaleimide (AMI), initiated by AIBN, were performed in THF solvent at 65°C. A series of copolymers of AMI-MMA, AMI-EA, and AMI-BA were prepared using different feed ratios of comonomers. The polymer samples have been characterized by solubility tests, intrinsic viscosity measurements, FT-IR, and ¹H-NMR spectral analysis, and thermo-gravimetric analysis. The values of monomer reactivity ratios r₁ and r₂ determined by Fineman-Ross and Kelen-Tudos methods are 0.43 and 0.42 in AMI/MMA, 0.72 and 0.62 in AMI/EA and 0.76 and 0.72 in AMI/BA systems. Alfrey-Price Q-e values for AMI are Q = 3.13 and e = 1.71 in AMI/MMA, Q = 1.10 and e = 1.46 in AMI/EA and Q = 1.02 and e = 1.63 in AMI/BA systems. It was found that the initial and final decomposition temperature increased with increasing the component of AMI in the copolymer.     

Copolymers of Phenoxyethyl Methacrylate with Butyl Methacrylate: Synthesis,Characterization and Reactivity Ratios

Phenoxyethyl methacrylate (POEMA) and butyl methacrylate (BMA) were copolymerized by free-radical copolymerization using α,α′-azobisisobutyronitrile (AIBN) in 2-butanone solution at 333±1 K. Copolymers were characterized by FTIR, ¹H-NMR and ¹³C-NMR spectroscopic methods and by comparison of the spectra with the corresponding homopolymers. Thermogravimetric analysis of the copolymers was carried out in order to know their thermal stability. Copolymer composition was established by ¹H-NMR analysis. Monomer reactivity ratios (MRR) were computed using the classical Fineman – Ross (FR) and Kelen – Tüdos (KT) procedures. MRR were also estimated using a nonlinear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). The mean sequence lengths of the copolymers were estimated and suggest that random copolymers were obtained.     

Synthesis,Characterization, Reactivity Ratio and Photo Crosslinking Properties of the Copolymer of 4-Cinnamoyl Phenyl Methacrylate with Butyl Methacrylate

Copolymers of 4-cinnamoyl phenyl methacrylate (4-CPMA) and n-butyl methacrylate (BMA) were prepared in a methyl ethyl ketone (MEK) solution with benzoyl peroxide (BPO) as an initiator at 70°C. They were characterized with UV, IR, ¹H-NMR, ¹³C-NMR, TGA, DSC and gel permeation chromatography. Copolymers were prepared by using different feed ratio of monomers. The monomer reactivity ratios determined by the method of Kelen-Tudos (K-T) were r₁ (CPMA) = 2.32, r₂ (BMA) = 0.56. The glass transition temperature of the copolymer shows a single Tg indicating the formation of random copolymer for all of the monomer feed composition. Thermogravimetric analysis in air has shown that the initial decomposition temperature of the copolymer was above 220°C. The photocrosslinking properties of the copolymer were examined by UV irradiation with polymer film.     

酯交换法合成碳酸甲乙酯催化剂的研究进展

碳酸甲乙酯（EMC）是一种环境友好型的不对称碳酸酯,因其独特的结构性质被广泛用作溶剂或有机合成中间体,特别是随着锂离子电池的迅猛发展,其作为电池电解液主要成分市场需求量急增。文中简单介绍了光气法、氧化羰化法和酯交换法合成碳酸甲乙酯的研究进展。重点针对最具发展前景的酯交换法合成EMC工艺路线中所用催化剂进行了综述;讨论和分析了该路线所用催化剂的类型、结构、性质及性能,并对当前研究中存在的问题进行了归纳和分析总结。最后本文分析并展望了酯交换法合成EMC催化剂的研究方向及新型合成工艺发展趋势,提出研发经济、高效、稳定且制备工艺简单的非均相催化剂,并与反应精馏技术耦合是今后的主要发展趋势,期望为EMC的高效合成提供参考和借鉴。     

High Resolution Crystal Structures of the Cerebratulus lacteus Mini-Hb in the Unligated and Carbomonoxy States

The nerve tissue mini-hemoglobin from Cerebratulus lacteus (CerHb) displays an essential globin fold hosting a protein matrix tunnel held to allow traffic of small ligands to and from the heme. CerHb heme pocket hosts the distal TyrB10/GlnE7 pair, normally linked to low rates of O(2) dissociation and ultra-high O(2) affinity. However, CerHb affinity for O(2) is similar to that of mammalian myoglobins, due to a dynamic equilibrium between high and low affinity states driven by the ability of ThrE11 to orient the TyrB10 OH group relative to the heme ligand. We present here the high resolution crystal structures of CerHb in the unligated and carbomonoxy states. Although CO binds to the heme with an orientation different from the O(2) ligand, the overall binding schemes for CO and O(2) are essentially the same, both ligands being stabilized through a network of hydrogen bonds based on TyrB10, GlnE7, and ThrE11. No dramatic protein structural changes are needed to support binding of the ligands, which can freely reach the heme distal site through the apolar tunnel. A lack of main conformational changes between the heme-unligated and -ligated states grants stability to the folded mini-Hb and is a prerequisite for fast ligand diffusion to/from the heme.     

天然纤维素蒸汽闪爆改性对其长支链酯合成影响

采用蒸汽闪爆技术对天然纤维素进行改性,并利用改性后的纤维素、乙酸酐和脂肪酸合成长支链纤维素酯。结果表明,蒸汽闪爆处理后纤维素葡萄糖环单元三个羟基的可及性及相对反应性能得到提高,同时缩短了反应周期。     

Novel Sulfonated CNN Pincer Ligands for Facile C−H Activation at a Pt(II) Center

Two novel sulfonated CNN-pincer ligands 1b and 1c and the corresponding chloro and aqua complexes K[^CNNLPtCl] and ^CNNLPt(H₂O), 3b – 3c and 2b – 2c , were prepared and fully characterized including single crystal X-ray diffraction. Along with the previously described complexes 2a and 3a , the derivatives of a CNN pincer ligand 1a , these complexes form a family of structurally similar compounds where the pincer core rigidity increases in the series 2a (3a) < 2b (3b) < 2c ( 3c ), as deduced from their XRD data. The increased ligand rigidity affects the aqua ligand dissociation energy of the ^CNNLPt(H₂O) complexes, as it follows from DFT calculations and as is reflected in the increased reactivity of the aqua complexes 2a , 2b and 2c in processes that involve aqua ligand loss. Among these processes the formation of the presumed dinuclear complexes ^CNNL₂Pt₂ and, importantly, catalytic C−D bond cleavage in C₆D₆ were studied in 2,2,2-trifluoroethanol solutions. The C−D bond cleavage reactivity was quantified as the rate of H/D exchange between C₆D₆ and CF₃CH₂OH at 80 °C.     

铂催化硅氢加成反应研究进展

硅氢加成反应是合成有机硅材料最重要的途径之一,铂催化剂作为其应用最广的催化剂,具有重要的意义。本文首先介绍了硅氢加成反应机理的研究现状;分析了聚合物长链段铂配合物、含多个铂原子铂簇化合物及N-杂环卡宾铂配合物均相铂催化剂的研究进展,致力于改善均相催化剂催化选择性差、催化活性难以控制等缺点;分别阐述了不同铂催化剂载体如无机二氧化硅、炭载体、金属氧化物、有机高分子、固载液等作为铂催化剂载体的优点,负载铂催化剂具有可回收、产物选择性好的优点,有效解决了工业上铂损失的问题;最后对铂催化硅氢加成反应的发展趋势进行了展望分析,铂负载能力的提高、铂负载催化剂的分离、硅氢加成反应的原理、催化范围的扩大等均是今后研究的重要方向。     

Two-State Reactivity: Personal Recounting of its Conception and Future Prospects

This essay tells the story of the conception of the Two-State Reactivity (TSR) notion. Since scientific career is part of life's flow, the story blends sub-stories of scientific colleagues and events. This is also a story of a beguiling paradigm, which has started from a puzzling reactivity of the diatomic oxidant FeO⁺, has continued to larger oxidants, like the active species of Cytochrome P450 and of nonheme enzymes, and its extension to reductive processes. Finally, the essay discusses prospects of experimental probing of the reactive spin-state, and of the transition state constitution for these reactions by means of tunneling-augmented kinetic isotope effects.