不饱和脂肪酸及其衍生物环氧化研究进展

综述了环氧化不饱和脂肪酸及其衍生物的制备工艺和实验方法,包括过氧酸环氧化法、卤代醇环氧化法、过氧化氢或有机过氧化氢环氧化法、分子氧环氧化法。其中使用过氧酸的方法是工业上使用最为广泛的,可以采用酸或者酶作催化剂;而以过氧化氢为氧化剂的固体催化工艺是目前最有工业化前途的技术。并指出了开发新型、高效、绿色且廉价的催化体系仍是今后的研究方向。     

PdCl2(bipy) complex—An efficient catalyst for Heck reaction in glycol–organic biphasic medium

The Palladium complex PdCl₂(bipy) (1) was found to be efficient in catalyzing the Heck reaction of aryl halides in a biphasic system comprising ethylene glycol along with an organic solvent. A proper tailoring of the organic phase ensured that the leaching of the catalyst to the organic phase was negligible. The catalyst was active for the Heck reaction of a number of olefins, aryl halides, in presence of organic and inorganic bases. The PdCl₂(bipy) catalyst was stable and could be recycled for five times without any loss in activity and selectivity. A major advantage of this work is that unlike hitherto reported biphasic systems; it does not employ a water-soluble ligand to achieve biphasic catalysis.     

Hybrid phosphazene-organosilicon polymers: II. High-polymer and materials synthesis and properties

Most of the polymers that have been synthesized and studied over the past 50 years are organic macromolecules. However, many advantages exist for the development of polymers with inorganic backbones. The first major class of inorganic backbone polymers to be developed widely were the polytorganosiloxanes] (silicones), and these now are the subject of broad industrial and fundamental interest. Polyphosphazenes are a relatively new class of inorganic backbone polymers which rival many organic systems in their molecular structural diversity and property variations. They constitute only the second group of inorganic-organic polymers to be developed extensively. An emerging field of research involves an attempt to create a new area of polymer science at the interface between these two subjects, by the synthesis of hybrid organophosphazene organosilicon systems. This review is a summary of recent progress in this new field.     

固体酸催化合成乙酸环己酯评述

固体酸是有机合成中能够替代硫酸的良好催化剂。评述了磺酸、无机盐、固体超强酸、杂多酸和分子筛等固体酸催化合成乙酸环己酯的方法。认为甲烷磺酸盐、氨基磺酸、强酸性阳离子交换树脂、结晶硫酸氢钠、固体超强酸和杂多酸适合催化合成乙酸环己酯。     

薯蓣皂素清洁化生产工艺及资源化利用研究进展

现有的薯蓣皂素传统生产工艺具有工艺简单、易操作的优点, 但在产率、能耗及环境污染等方面存在较大问题。本文综述了国内外薯蓣皂素清洁化生产工艺的研究进展, 介绍了两类清洁化生产工艺--传统无机酸水解改进工艺和非无机酸水解工艺, 着重概述了发展前景较好的非无机酸水解工艺, 包括离子交换树脂催化法、离子液体催化法、生物转化法以及热分解处理法, 并比较了不同工艺的优缺点。指出传统无机酸水解改进工艺虽能减少无机酸对环境的污染, 大部分还能提高皂素产率, 但废水废渣的问题仍然没有解决;非无机酸水解工艺几乎零污染排放, 但存在产率低、成本高等不足。本文同时简述了从黄姜提取皂素过程中废水废渣的综合利用方法, 总结了清洁化生产工艺和废渣利用中存在的问题, 提出未来应以提高非无机酸水解工艺的皂素产率为研究重点, 并对废渣的资源化利用不断进行探索和开发。     

Application‐directed syntheses of surface‐functionalized organic and inorganic nanoparticles

An overview of the formation of inorganic and organic particles in emulsions is presented. The key aspect in these syntheses is the use of specially designed surface‐active components. Examples of synthesis‐driven approaches to various functional nanoparticles are illustrated. Surfmers based on isophthalic acid give access to particles for highly stabilized emulsions. Amphiphilic block copolymers as emulsifiers result in particles with excellent film‐forming properties or which are applicable as supports for metallocenes. Amphiphilic statistical copolymers are used for the compatibilization of inorganic nanoparticles in hybrid materials. Block and statistical copolymers are versatile stabilizers of non‐aqueous emulsions. In such systems nanoparticles obtained by either water‐sensitive monomers or catalysts can be realized. Surface functionalization with aliphatic or aromatic amines results in latex particles, which are suitable as supports for postmetallocenes or as flocculants in the papermaking process. In each area, the incorporation of the amphiphiles at the nanoparticle surface is not only important for the particle formation itself, but also decisive for the applicability of the particles. Copyright © 2007 Society of Chemical Industry     

纳米结构酶催化剂研究进展

将酶负载于载体上可以提高工业应用中酶的稳定性并便于重复使用。纳米材料的发展为固定化酶提供了新的契机,利用纳米材料固定化酶有望进一步提高酶在工业环境中的催化性能、拓展固定化酶的应用范围。本文主要关注近年来在纳米结构酶催化剂方面的研究进展,重点介绍本研究组以无机晶体、金属有机骨架材料、石墨烯和功能高分子等为载体进行酶固定化以及酶催化过程多尺度分子模拟方法的研究进展,讨论了纳米结构酶催化剂的发展前景。     

Chiral Synthesis on Catalysts Immobilized in Microporous and Mesoporous Materials

Abstract

This paper reviews the recent progress made in the asymmetric synthesis on chiral catalysts in porous materials and discusses the effects of surface and pores on enantioselectivity (confinement effect). This paper also summarizes various approaches of immobilization of the chiral catalysts onto surfaces and into pores of solid inorganic supports such as microporous and mesoporous materials. The most important reactions surveyed for the chiral synthesis in porous materials include epoxidation, hydrogenation, hydroformylation, Aldol and Diels‐Alder reactions, etc. The confinement effect originated from the surfaces and the pores turns out to be a general phenomenon, which may make the enantioselectivity increase (positive effect) or decrease (negative effect). The confinement effect becomes more pronounced particularly when the bonding between the catalyst and the surface is more rigid and the pore size is tuned to a suitable range. It is proposed that the confinement in chiral synthesis is essentially a consequence of subtle change in transition states induced by weak interaction in pores or on surfaces. It is also anticipated that the enantioselectivity could be improved by tuning the confinement effect based on the molecular designing of the pore/surface and the immobilized catalysts according to the requirements of chiral reactions.     

Hybrid organic-inorganic solids for heterogeneous asymmetric catalysis

This paper provides a short review of recent progress in the design and synthesis of chiral organic–inorganic hybrid solids and their applications in heterogeneous asymmetric catalysis. Homochiral hybrid solids containing catalytic sites can be readily prepared by linking appropriately designed chiral bridging ligands with metal ion or metal cluster nodes. Heterogeneous asymmetric catalysts with enantioselectivity as high as 99.2 and turnover number (TON) as high as 20,000 have been obtained based on these hybrid organic–inorganic solids. The modular nature of the present approach promises to lead to a variety of practically useful heterogeneous asymmetric catalysts for many organic transformations.     

Advances and perspectives in catalysts for liquid-phase oxidation of cyclohexane

The latest progress and developments in catalysts for the oxidation of cyclohexane are reviewed. Catalytic systems for the oxidation of cyclohexane including metal supported, metal oxides, molecular sieves, metal substituted polyoxometalates, photocatalysts, organocatalysts, Gif systems, metal-organic catalysts and metalloporphyrins are discussed with a particular emphasis on metalloporphyrin catalytic systems. The advantages and disadvantages of these methods are summarized and analyzed. Finally, the development trends in the oxidation technology of cyclohexane are examined.     

Heterogeneous Enzyme Mimics Based on Zeolites and Layered Hydroxides

Careful combination of a metal compound,a ligand and an inorganic support material leads to supramolecular catalysts that mimic the structural, organizational and functional aspects of enzyme activity.After discussing essential features of metalloenzyme-catalyzed reactions and coordination chemistry in inorganic hosts, we present examples of supramolecular materials selected from our own work that eventually resulted in useful catalysts for organic transformations in the liquid phase.     

Hybrid phosphazene-organosilicon polymers: I. Background, rationale, and small-molecule model compound chemistry

Most of the polymers that have been synthesized and studied over the past 50 years are organic macromolecules. However, many advantages exist for the development of polymers with inorganic backbones. The first major class of inorganic backbone polymers to be developed widely were the poly(organosiloxanes) (silicones), and these now are the subject of broad industrial and fundamental interest. Polyphosphazenes are a relatively new class of inorganic backbone polymers which rival many organic systems in their molecular structural diversity and property variations. They constitute only the second group of inorganic-organic polymers to be developed extensively. An emerging field of research involves an attempt to create a new area of polymer science at the interface between these two subjects, by the synthesis of hybrid organophosphazene organosilicon systems. This review is a summary of recent progress in this new field.High Polymer and Materials Synthesis and Properties: Part II will appear in the next issue of this journal.     

Bioactive Sol‐Gel Coatings

Recent sol‐gel techniques enable bioactive composite layers to be prepared by the embedding of bioactive compounds, biomolecules (BMs) and cellular systems within inorganic layers. These novel bioactive layers offer interesting new applications, e.g. biocompatible coatings on implants and medical products, the preparation of biosensors and biocatalysts, and coatings that can release biocides in a controlled manner.     

Radiation-induced solid-state polymerization in binary systems. IX. Polymerization and foaming of multicomponent systems including inorganic acid and acrylic monomers

It was found that binary systems consisting of inorganic acid and organic amide or nitrile form a stable glassy phase owing to the large molecular interaction between the components. The change in T_g values with change in composition of these binary systems was studied. Gamma ray-induced polymerization of inorganic acid and acrylamide or acrylonitrile systems was carried out in a supercooled phase. The polymerization rates in acrylamide–inorganic acid systems had a maximum at a temperature T_v (30°–50°C higher than the glass transition temperature), but in acrylonitrile–inorganic acids systems there was no maximum rate at any temperature. Foaming occurred during irradiation in the polymerization of acrylamide–urea–sulfuric acid system. The insource foaming was attributed to the promoting effect of sulfuric acid for the decomposition of urea and the heat accumulation by the acceleration of the polymerization.     

无机膜及无机膜反应器的发展和应用

无机膜具有强度高、孔径容易控制、化学性质稳定、热稳定性好、易再生和不易老化等优点,成为膜技术领域重要研究方向,膜反应器是它的应用之一。综述了无机膜的发展状况,包括无机膜的分类和最新研究,无机膜反应器的特点、类型和它的作用;重点介绍了无机膜的应用和无机膜反应器的分类及应用研究,并提出了实现其工业化的不足。     

Microstructural features, diffusion and molecular relaxations in polyimide/silica hybrids

FTIR spectroscopy has been used to investigate the microstructure of the inorganic phase in polyimide/silica hybrids obtained by the sol-gel route. It has been shown that the presence of a coupling agent (GOTMS) strongly influences the silica phase by favoring the formation of linear, branched chains which make the structure loosely interconnected. The morphological changes induced by GOTMS are reflected in the water sorption properties of the investigated systems. Due to the hydrophilic nature of the silica phase, the amount of sorbed water increases in the hybrid systems in comparison to the pristine polyimide, and among the two hybrids, increases more in the two-phase system than in the co-continuous. Molecular interactions of the hydrogen-bonding type have been identified between the imide units and the H₂O molecules, both in the polyimide and in the hybrid systems. Finally, the sub-T_g relaxation processes have been investigated in detail by dynamic-mechanical analysis coupled with molecular mechanics simulations. Considerable effects of the inorganic phase on these processes were observed, especially for the case of the co-continuous systems, and were accounted for by molecular scale contiguity among the phases.     

Water-soluble sulfonated amino-formaldehyde resins. II. Characteristics as dispersing agents

The use of sulfonated melamine–formaldehyde resins as dispersants with inorganic materials was investigated, and the effect of these dispersants on the rheology of cement pastes was studied. The improvement in compressive strength of sand and mortar was also investigated. Results show that these polyanionic resins are effective dispersing agents when they are mixed with inorganic materials. Significant improvements in the flow and compressive strength of these systems can be realized when small quantities of the water-soluble polymers are added. The effect of reaction conditions on the molecular structure and its effect on performance is discussed.     

Synthesis and Characterization of Hybrid Core–Shell Systems Based on Molecular Silicasols

New hybrid “rigid inorganic core–soft organic shell” systems based on molecular silicasols were synthesized by applying different synthetic schemes. Inorganic core was composed of molecular silicasols, which were synthesized from hyperbranched polyethoxysiloxane and tetraethoxysilane by polymer chemistry methods. Different organic modifiers were used to form soft shell of the hybrid particles. Obtained compounds were characterized by elemental analysis, GPC, IR and NMR spectroscopy. These systems will be designated for use as model objects for investigation of nanoparticles–polymer matrix interactions in polymer nanocomposites.     

Highly Selective Biphasic Telomerization of Butadiene with Glycols: Scope and Limitations

Highly selective telomerization reactions of a number of short‐chain glycol nucleophiles with 1,3‐butadiene have been achieved in aqueous biphasic systems employing the water‐soluble catalyst system Pd(acac)₂/TPPTS. For all substrates the selectivity for the obtained monotelomers 5 – 7 reached ≥95% whereas butadiene dimers 3 , octadienols 4 and ditelomers like 2 were produced only in trace amounts. The order of reactivity is ethylene glycol>>1,3‐propylene glycol ≈ glycerol>1,4‐butylene glycol, which is in agreement with generally observed trends. The scope and limitations of these reactions are discussed in terms of obtained yields and achievable catalyst productivities (total turnover numbers).