超临界二氧化碳中合成环碳酸酯的催化剂研究进展

超临界二氧化碳(sc CO2)是一种环境友好型溶剂,它作为传统有机溶剂的替代品已被广泛应用于绿色化学过程的开发。其中,环氧化合物在超临界二氧化碳中制备环碳酸酯是实现二氧化碳高附加值转化的有效途径之一。本文回顾了近年来在超临界二氧化碳中合成环碳酸酯的研究进展,着重介绍了不同种类的催化剂,包括金属配合物、季盐、二元催化体系、离子液体、金属氧化物、有机小分子及其他类型催化剂在该反应体系中的应用,突出了超临界二氧化碳既作为溶剂,又作为反应物的双重优势。从经济和环境角度考虑,离子液体或季盐等有机催化剂具有更好的工业化应用前景。同时,指出了高效和绿色催化体系设计和创制是该研究领域的关键。     

低成本环状碳酸酯新工艺诞生

近日,南开大学的科研人员开发出了一种新型固体催化剂用于制备环状碳酸酯,这种高分子负载催化剂可做到一相反应、两相分离,利用二氧化碳与环氧化物加成反应合成环状碳酸酯,大大简化了工艺流程,产品无需经过分离、纯化过程,纯度就可达到99%以上,且生产成本大大降低。该新工艺的技术路线是:设计并合成非均相催化剂和亲二氧化碳的均相催化剂,用超临界二氧化碳作为溶剂,实现催化剂与产物的直接分离并循环使用。这一对二氧化碳温室气体的资源化利用技术具有广阔的应用前景。     

二甘醇双烯丙基碳酸酯的合成方法

本发明二甘醇双烯丙基碳酸酯的合成方法涉及从二氧化碳制备碳酸酯，在二甘醇双烯丙基碳酸酯的合成反应中以烷基胍类化合物为催化剂，具体步骤是：向高压反应釜内加入二甘醇、碳酸钠、和氯丙烯，其摩尔比为二甘醇：     

其他

超临界CO2无催化剂合成工艺 开发成功 日本东北国立研究所(TNRI)开发了用超临界CO2从环氧化物有效合成碳酸酯的无催化剂工艺。在合成中,这种CO2既是参与反应的原料,也是反应用的溶剂。由于没有有害的催化剂,这种环境友好工艺受到各有关方面的极大关注。     

手性噁唑啉配体的合成及在偶联反应中的应用

该实验以不同手性氨基醇为原料,设计合成了含有不同官能团的三种双噁唑啉手性化合物P1、P2和P3,利用1H NMR和LC-MS进行结构表征,并以其为配体,与Bu4NAu Cl4/HAu Cl4构建催化反应体系,应用于叔胺与亚磷酸二烷基酯交叉脱氢偶联反应合成a-氨基磷酸衍生物,并探索双噁唑啉的结构、金催化剂的类型等因素对反应的影响。实验结果表明,配体P3和Bu4NAu Cl4反应体系具有良好的催化活性。     

由二氧化碳出发合成有机碳酸酯

对以二氧化碳为原料合成有机碳酸酯的环氧路线、酯交换和直接合成方法作了综合评述 ,认为直接合成是最佳的合成路线。碳酸酯的直接合成可在均相及多相催化体系中进行 ,负载金属、金属甲氧基化合物及碱均可作为催化剂。直接法研究的关键在于高性能催化剂的开发、由二氧化碳对金属 -氧键插入反应导致的催化循环的构筑及耦合反应的应用。     

非异氰酸酯路线合成聚羟氨酯的研究

由非异氰酸酯路线合成聚氨酯,避免使用有毒、难运输和贮存的异氰酸酯,是聚氨酯的绿色合成路线,属于高分子合成化学的前沿课题。本文报道了一种由双环碳酸酯与二元胺加成聚合制备聚羟氨酯的新路线,其中双环碳酸酯是由含双环氧基团的环氧树脂与二氧化碳(CO 2)在双金属氰化络合物与季铵盐组成的二元催化剂催化下高效偶合反应得到。双环碳酸酯在季铵盐催化下与二元胺加成聚合,得到聚羟氨酯。由此提供了一条以环氧树脂、C O2和二元胺为原料合成聚羟氨酯的新途径。     

离子液体催化二氧化碳合成环状碳酸酯的研究进展

离子液体作为一种新型绿色环保介质,由于其结构可设计、稳定性高以及催化活性高等优点,使其在CO_2环加成反应的催化方面应用前景广阔。本文综述了近年来离子液体催化CO_2与环氧化物的环加成反应制备环状碳酸酯的研究进展。传统离子液体包括咪唑类、吡啶类、季铵盐季盐等离子液体,而功能化离子液体包括羟基功能化、羧基功能化等离子液体。与传统离子液体相比,功能化离子液体具有更好的催化活性。无机或有机材料负载的非均相离子液体催化剂报道较多,载体包括SiO_2、氧化石墨烯、聚合物等。非均相催化剂具备易分离、可在固定反应器中连续反应等优点,更适应工业化生产。指出了CO_2与环氧化合物反应制备环状碳酸酯过程中出现的催化剂活性低、反应条件苛刻等关键问题,因此寻求高选择性合成环状碳酸酯的环境友好的新型高效催化剂具有重要的学术意义和实用价值。     

二氧化碳与环氧烷加成反应的金属配合物催化剂及活化机理研究进展

综述了环氧烷与CO2开环加成反应合成环状碳酸酯的金属配合物催化剂的研究进展,讨论了金属配合物催化活化环氧烷和CO2完成环加成反应的活化机理,为CO2的化学利用及环氧烷合成环状碳酸酯工艺的研究、开发与应用提供参考。     

离子液体功能化salen Mn催化苯乙烯与CO2一锅合成碳酸苯乙烯酯

合成了咪唑离子液体功能化salen Mn配合物（IL-salen Mn）,并作为唯一催化剂成功应用于苯乙烯与二氧化碳一锅合成碳酸苯乙烯酯反应中。首先,以尿素过氧化氢（UHP）为氧化剂、吡啶氮氧化物（PyNO）为助剂,催化苯乙烯高效制备环氧苯乙烷,继而催化环氧苯乙烷与二氧化碳发生环加成反应合成碳酸苯乙烯酯。分别考察了催化剂的种类和用量、助剂用量、氧化剂种类和用量、反应时间以及反应温度等因素对上述反应的影响。当催化剂用量为8 mol%（以反应物总的物质的量记）,n(苯乙烯)∶n(UHP)∶n(PyNO)=1.0∶3.0∶0.2,环氧化反应温度和时间分别为30 ℃和5 h,环加成反应温度和时间分别为80 ℃和12 h,二氧化碳压力为1 MPa时,苯乙烯的转化率为90%,碳酸苯乙烯酯收率达到32%。结合前期研究与反应时间动力学结果,推测了该串联反应可能的机理。     

绿色化学的研究现状及进展

绿色化学又称环境无害化学、环境友好化学、清洁化学,是当今国际化学科学研究的前沿课题,其目的是将现有化工生产技术路线从“先污染,后治理”改为“从源头上根除污染”。绿色化学具有良好的现实经济效益和深远的社会效益,是知识经济时代化学工业发展的必然趋势。介绍了绿色化学的发展现状,并对其发展方向提出了一些见解。     

Kinetic parameters of thermal degradation of polyethylene glycol‐toughened novolac‐type phenolic resin

The miscibility and thermal degradation of poly(ethylene glycol) (PEG)‐toughened novolac‐type phenolic resin were investigated. Differential scanning calorimetry (DSC) results confirmed that the phenolic resin/PEG blend was blended completely. Infrared spectra show that hydrogen bonding existed in the blends. Thermal degradation of PEG blended with novolac‐type phenolic resin was studied utilizing a dynamic thermogravimetric technique in a flowing nitrogen atmosphere at several heating rates (i.e., 5, 10, 20, 40°C/min). Thermal degradation of phenolic resin/PEG blends takes place in multiple steps. The thermal behavior and the thermal stability affected the thermal degradation, which coincided with the data from the thermal degradation of novolac‐type phenolic resin/PEG blends by thermogravimetric analysis (TGA). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 188–196, 2001     

Blends of novel L‐tyrosine‐based polyurethanes and polyphosphate for potential biomedical applications

Elastomeric biodegradable polyurethanes and polyphosphate have been developed using an L ‐ tyrosine‐based diphenolic monomer desaminotyrosine‐tyrosine hexyl ester (DTH). Soft segments, which are polycaproloctone diol (PCL) and polyethylene glycol (PEG) have been used for the synthesis of two biodegradable L ‐tyrosine polyurethanes (LTUs), which are PEG‐C‐DTH and PCL‐C‐DTH. An investigation of the physico‐chemical properties shows that these polymers have dramatically different properties. By blending LTUs with L ‐tyrosine polyphosphate (LTP), we hope to produce a family of materials with a wide range of thermal, morphological, surface, and degradative properties. Examination of the blends shows a smooth surface morphology with a partially phase‐separated structure. These findings are consistent with the results obtained from thermal analysis of the blends. Hydrophilic nature of PEG imparts the PEG‐based blends (PEG‐C‐DTH/LTP) with a significantly higher surface and bulk hydrophilicity compared with the PCL‐based blends (PCL‐C‐DTH/LTP). Finally, the blends demonstrate a rapid initial hydrolytic degradation in phosphate buffered saline (PBS) followed by a significantly slower, prolonged degradation. The observed trend may occur due to the rapid hydrolytic degradation rate of the polyphosphate polymer followed by the degradation of the polyurethane component. Thus, tuning the physical properties by blending LTUs with LTP may be useful for drug delivery device and soft tissue engineering scaffold applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

超临界二氧化碳介质中的烃类氧化反应

介绍了有关烷烃、烯烃、芳烃化合物在超临界CO2介质中进行的氧化反应。以超临界CO2介质代替有机溶剂的环境友好方式,并采用环境友好的氧化剂氧气或过氧化氢,研究烃类化合物的氧化反应,对于化工中间体的开发研究以及绿色石油化工的发展具有重要意义和应用价值。研究结果表明,以超临界CO2作为反应介质的氧化反应,具有广阔的发展前景。     

Synthesis of three‐arm poly(ethylene glycol) by combination of controlled anionic polymerization and ‘click’ chemistry

Poly(ethylene glycol) (PEG) is an important water‐soluble polymer, which is widely used in the biomedical field because of its good biodegradability, biocompatibility and permeability. It is usually synthesized by anionic polymerization of ethylene oxide but side reactions lead to the formation of some oligomers. High molecular weight PEG can be obtained, however, through coordinated anionic polymerization. Recently a novel controlled anionic polymerization based on the initiating system ammonium bromide/trialkylaluminium was reported. Related studies have shown that the controlled anionic polymerization allows the synthesis of linear polyethers with low dispersity in a wide range of molecular weights at ambient temperature. Unfortunately, so far this controlled anionic polymerization has not been used to synthesize polymers with complex architectures. In the work reported here, controlled anionic polymerization was combined with ‘click’ chemistry for the first time to synthesize polyethers with multiple arms. Firstly, controlled anionic polymerization was employed to synthesize a linear bromine‐terminated PEG (PEG‐Br) using ethylene oxide as the monomer and tetraoctylammonium bromide/triisobutylaluminium as the initiating system at room temperature. The terminal bromine in the PEG thus synthesized was then converted into an azide group by the reaction of PEG‐Br and sodium azide. A trifunctional linking agent was also prepared by the reaction of trimethylolpropane and propiolic acid. By using ‘click’ chemistry, a three‐arm PEG was finally obtained through the reaction of the azide‐terminated PEG and the trifunctional linking agent. The chemical structure of the polymer thus synthesized was characterized using infrared spectroscopy, NMR spectroscopy, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and size‐exclusion chromatography with multi‐angle laser light scattering. It was found that the synthesized polyether possesses the designed structure. Considering the wide applicability of controlled anionic polymerization and ‘click’ chemistry, their combination is a valuable way to synthesize various polyethers with multiple arms. Copyright © 2009 Society of Chemical Industry     

Degradation of poly(ethylene glycol) by electrolysis during the Cu electroplating: A combined experimental and density functional theory study

The polymer additives are key factor materials in the Cu electroplating process, essential for controlled acceleration and inhibition of Cu deposition. In this study, the degradation behavior of a polymer additive—poly(ethylene glycol) (PEG)—during the Cu electroplating was investigated by MALDI‐TOF MS technique. The PEG was completely degraded after 4 h at a constant electric current density of 13 mA/cm², whereas it showed no degradation without an electric field even at a very low pH (pH < 1). The pathways and energetics of PEG degradation by electrolysis in aqueous chloride medium was investigated using density functional theory calculations at the same time. It demonstrated how facile the decomposition of PEG internal radical is, which is generated via the hydrogen abstraction from PEG by hydroxyl radical formed at the anode in aqueous chloride medium under an electric field. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

苄胺在超临界水中脱氮机理的量子化学计算

针对苄胺在超临界水中的脱氮机理,通过实验和量子化学计算相结合的方法进行了研究。使用Gaussian09计算软件在M06/6-311G（d,p）和M06-2X/6-311+G（d,p）计算水平上进行量子化学计算。结果表明,苄胺在超临界水中的脱氮过程遵循协同反应机理而不是自由基机理。两步脱氢反应是苄胺的主要脱氢反应,其能垒（181.4 kJ·mol^-1）比一步脱氢反应低118.7 kJ·mol^-1。由脱氢反应得到的苯甲醛进一步与苄胺反应生成亚苄基苯胺（BBA）,BBA与超临界水继续反应实现脱氮过程。此外,通过比较有水催化和无水催化的反应能垒,发现超临界水分子对苄胺脱氮过程具有显著的催化作用。     

绿色化学及其技术在水处理的应用

近年来绿色化学及其技术的应用已经成为环境保护和防止污染的重要方面。绿色化学可将污染控制在一定水平 ,即在化学品的制造和应用中降低或消除有毒有害物质。水处理缓蚀剂和阻垢剂作为一类化学品 ,如果在这些领域应用绿色化学技术 ,可以减少或消除许多有毒有害的化学品 ,并在此基础上开发新型的环境友好型的水处理药剂。     

The Development of Visible-Light Photoredox Catalysis in Flow

Visible-light photoredox catalysis has recently emerged as a viable alternative for radical reactions otherwise carried out with tin and boron reagents. It has been recognized that by merging photoredox catalysis with flow chemistry, slow reaction times, lower yields, and safety concerns may be obviated. While flow reactors have been successfully applied to reactions carried out with UV light, only recent developments have demonstrated the same potential of flow reactors for the improvement of visible-light-mediated reactions. This review examines the initial and continuing development of visible-light-mediated photoredox flow chemistry by exemplifying the benefits of flow chemistry compared with conventional batch techniques.     

Hydrolytic and thermal degradation of polyethylene glycol compatibilized poly(lactic acid)-nanocrystalline cellulose bionanocomposites

This study investigates the effect of nanocrystalline cellulose (NCC) and polyethylene glycol (PEG) on the hydrolytic degradation behavior of poly(lactic acid) (PLA) bio-nanocomposites compared with that of neat PLA, under specific environmental condition, namely at 37°C in a pH 7.4 phosphate buffer medium for a time period up to 60 days. The water absorption, mass loss, molecular weight, and the morphologies of nanocomposites before and after degradation were explored. Thermogravimetric analysis (TGA) was used to study the thermal decomposition of the PLA/NCC/PEG nanocomposites before and after degradation. The results showed that the presence of hydrophilic NCC and PEG significantly accelerated the hydrolytic degradation of PLA, which was related to the rapid dissolution of PEG causing easy access of water molecules to the composites and initiating fast hydrolytic chain scission of PLA. The thermal degradation temperatures of the nanocomposites slightly decreased due to the poor thermal stability of NCC in comparison with that of the neat PLA. After degradation, the thermal stability of the separated PLA from nanocomposites significantly decreased because the molecular decreased during the hydrolytic process. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46933.