聚合物固载催化剂的研究进展

介绍聚合物固载催化剂有6类,包括离子交换树脂催化剂,聚合物固载的相转移催化剂,聚合物固载的酸催化剂,聚合物固载的碱催化剂,聚合物固载的金属催化剂,聚合物固载的生物催化剂等。综述了近年来聚合物固载催化剂的研究进展。     

聚合物固载催化剂的研究进展

综述了近年来聚合物固载催化剂的研究进展。介绍的聚合物固载催化剂有6类，包括离子交换树脂催化剂、聚合物固载的相转移催化剂、聚合物固载的酸催化剂、聚合物固载的碱催化剂、聚合物固载的金属催化剂、聚合物固载的生物催化剂等。     

Polymers as Catalysts

Polymers have been widely used as catalysts or catalyst supports and the various applications can be categorised conveniently into four groups (a) catalysis by soluble linear polymers, (b) catalysis by ion exchange resins, (c) polymer-supported ‘homogeneous’ metal complex catalysts and (d) polymer-supported phase transfer catalysts. A brief review of each of these is given, with citation of some of the more recent and important examples which illustrate some of the basic principles involved.     

高分子负载催化剂的应用研究进展

高分子负载催化剂具有稳定性高、溶剂适用性广、易于产物分离纯化、对环境影响小、易从反应体系中分离回收和重复使用等优点,受到人们极大的重视。从高分子负载催化剂的特点、种类等方面综述了高分子负载催化剂不同于低分子金属络合物的催化性能,以及其应用进展。     

高分子负载钛酸酯催化剂的制备及其在高沸点酯合成中的应用

聚乙烯醇与四氯化钛在二甲基亚砜和无水乙醇混合溶剂中反应,制得负载钛酸酯催化剂PVAC-1,用红外光谱对其分子结构进行了表征,用比色法测定了催化剂中的Ti含量。研究了PVA–1在邻苯二甲酸二异辛酯（DOP）、己二酸二庚酯、苯甲酸异辛酯等高沸点酯合成过程中的活性。结果表明该催化剂具有与烷基钛酸酯Ti(OBu)4相当的催化活性。在催化合成上述3种高沸点酯时有机酸转化率分别达到99.8%、97.5%和99.7%。催化剂可多次重复使用。     

Polymer-supported N-heterocyclic carbene-iron(III) catalyst and its application to dehydration of fructose into 5-hydroxymethyl-2-furfural

Polymer-supported NHC–metal catalysts were prepared from chloromethyl polystyrene resin via two-step reaction. Metals were loaded into 1.6 – 16 mol% of total imidazolium and the remaining imidazolium chloride salt provided ionic liquid moiety. The formation of metal complex with the polymer-supported NHC ligand was analyzed by ATR FT-IR, XRD, and XPS. The synthesized polymer-supported NHC–metal catalysts were applied to the dehydration of fructose into HMF. The environmentally benign and inexpensive polymer-supported NHC–Fe^III catalyst showed good catalytic activity and yielded HMF at 73% (with a conversion of 97%). It could also be reused without significant loss of catalytic activity.     

Preparation of Tethered Half-Titanocene Complex on Syndiotactic Poly(styrene-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">p</Emphasis>-methylstyrene) for Using in Syndiospecific Polymerization of Styrene

Abstract  

In this work the syndiotactic polystyrene copolymer, poly (styrene-co-p-methylstyrene) was prepared by the copolymerization of styrene and p-methylstyrene with cyclopentadienyltitanium trichloride/methylaluminoxane catalyst. This copolymer was functionalized with silyl-hydride groups. The structure of copolymer and functionalized copolymer were characterized by FT-IR, ¹H-NMR and ¹³C-NMR spectroscopy. The obtained results revealed that the functionalization reaction successfully proceeds at low temperatures. Tethering of half-titanocene complex on polymeric support was done by the hydrosilylation reaction of 1-allylindenyltrichlorotitanium with silyl-hydride functionalized copolymer in the presence of Karstedt catalyst as a coupling reagent. The polymer-supported catalyst was tested for syndiospecific polymerization of styrene using methylaluminoxane as a cocatalyst. The results of styrene polymerization showed that the polymer-supported catalyst exhibited high activity for syndiospecific polymerization of styrene. The polymer prepared with supported catalyst was characterized by carbon nuclear magnetic resonance (¹³C-NMR) and differential scanning calorimetry (DSC). The results confirmed the syndiotacticity of obtained polymers. X-ray diffraction (XRD) analysis showed the δ-form crystalline structure of obtained syndiotactic polystyrene.     

可溶聚合物支载催化剂

可溶聚合物支载催化剂是当今“绿色化学”研究的热点问题之一。本文介绍了近几年来可溶聚合物支载催化剂,包括可溶聚乙二醇、可溶聚丙烯酰胺和可溶非交联聚苯乙烯支载催化剂的研究情况及其在有机合成中的应用。     

Novel polymer-supported phosphine palladium catalyst: one-pot synthesis from and application in Suzuki–Miyaura coupling reaction

A “one-pot” strategy has been developed for the synthesis of polymer-supported phosphine-Pd catalyst using Suzuki–Miyaura coupling reaction. The fine and uniform Pd nanoparticles were well dispersed on the skeleton of the phosphine-containing polymer. This Pd catalyst exhibited excellent catalytic activity and recycling performance in the Suzuki–Miyaura coupling reaction under the mild conditions and water–ethanol mixed media.     

高分子负载铁催化剂的制备及其甲苯选择性氯化反应性能

通过金属铁离子与高分子载体进行螯合反应,制备高分子负载铁催化剂,用原子吸收光谱法测定催化剂中Fe3+含量,并利用傅里叶变换红外光谱仪、扫描电子显微镜、热重分析对制备的催化剂分子结构、微球形貌和热稳定性进行表征,并研究有机硫助催化剂的添加对高分子负载铁催化剂催化甲苯选择性氯化性能的影响。结果表明,铁离子与乙酰丙酮基的两个氧原子形成了六元螯合环的强相互作用,使Cl2分子更易极化,提高了催化反应速率;有机硫助催化剂不仅改变Cl—Cl键的强度,而且增大了亲电试剂的空间位阻,从而显著提高对位选择性和稳定性。1%(占甲苯的质量分数)高分子负载铁催化剂/0.05%(占甲苯的质量分数)有机硫助催化剂催化甲苯选择性氯化反应表现出最佳的催化性能,氯化反应2 h,甲苯转化率超过90%,对氯甲苯选择性55.74%,多氯甲苯质量分数低于1%。催化剂可重复使用。     

Vanadium Complexes Based Polymer Supported Catalysts: A Brief Account of Research from Our Group

Solid supported catalysts can go a long way in developing catalyst based technology because of their high efficiency with recyclability and easy separation from the reaction mixture. Immobilizations of homogeneous catalysts through covalent bond with chloromethylated polystyrene cross-linked with divinylbenzene and develop them as environmentally safe heterogeneous catalysts for oxidation reaction have attracted attention in recent years. Recently, effort from our research laboratory was to synthesize new recyclable polymer-supported vanadium complexes based heterogeneous catalysts. Thus, chloromethylated polystyrene cross linked with 5% divinylbenzene was used as support to prepare variety of polymer supported vanadium catalysts. These catalysts have successfully been used for the oxidation and oxidative bromination of various organic substrates. Keeping in mind the industrial usage of these heterogeneous catalysts, the leaching and recycle ability of all polymer-supported catalysts have also been tested. Most catalysts are stable and do not leach during the catalytic reactions.     

Alkylation of Hydroquinone with tert-Butanol Catalyzed by Polymer-supported Sulfonimide

Polystyrene with pendant perfluorobutylsulfonylimide (PPFSI) was developed as a novel polymer-supported strong acid catalyst for alkylation of hydroquinone (HQ) with tert-butanol (TBA), and highly selective synthesis of 2-tert-butyl hydroquinone (2-TBHQ) was investigated over PPFSI under various experiment conditions. When the molar ratio of TBA to HQ was 1.2:1, using 3 mol% of PPFSI as catalyst in 1,2-dichloroethane at 130 °C for 5 h, the maximum of selectivity (85.9%) of 2-TBHQ was obtained while the conversion of HQ was 76.7%. Compared with other solid acid catalysts PPFSI was found to be a very effective and reusable catalyst for alkylation of hydroquinone with tert-butanol.     

Anodic oxidation of benzyl alcohol to benzaldehyde in the presence of both redox mediator and polymer-supported phase-transfer catalyst

Using a polymer-supported phase-transfer catalyst (PTC) and a redox mediator, Cl^–/OCl^–, the anodic oxidation of benzyl alcohol was studied. The polymer support used in this study was synthesized by the method of suspension polymerization. The results revealed that on decreasing the crosslinking and increasing the content of chloromethylstyrene in the polymer support, the number of phase transfer active sites, tri-n-butylphosphine, in the polymer-supported PTC increased. The anodic oxidation of benzyl alcohol in the presence of the redox mediator, Cl^–/OCl^–, and polymer-supported PTC occurred in the reaction controlled region when the stirring rate exceeded 400 r.p.m. The results also revealed that the current efficiency for the anodic oxidation of benzyl alcohol was mainly affected by the characteristics and weight of the polymer-supported PTC, the pH, and the concentration of benzyl alcohol. However, the temperature affected the current efficiency only slightly.     

Catalytic Potential of a New Polymer-Anchored Multisite Phase Transfer Catalyst in the Dichlorocarbene Addition to Indene

The popularity of triphase catalysis in industries is due to straightforward catalyst recovery from reaction mixture. In this work we report a facile preparation a new polymer-anchored multisite phase transfer catalyst viz., polymer-anchored-2-benzyl-2-phenyl-1,3-bis(triethylmethylene ammonium chloride) (PABPBTAC) using polystyrene-based cross-linked beads. In order to ascertain the catalytic efficiency of the new heterogeneous catalyst, we studied its catalytic activity in the conversion of indene into dichlorocyclopropyl indene using chloroform and sodium hydroxide. Comparative catalytic efficiency of the new polymer-anchored multisite phase transfer catalyst with polymer-supported single site onium salts revealed that the new heterogeneous phase transfer catalyst is highly active than others. Further, from the influence of variation of experimental parameters, such as [substrate], [catalyst], [NaOH], stirring speed and temperature on indene conversion was studied in detail.     

微波／催化氧化法对废水中苯胺降解的研究

采用微波催化氧化法对苯胺模拟水的处理进行了初步的探讨分析;考察了微波时间、微波功率、pH值、H2O2浓度、高分子负载型催化荆质量对废水中苯胺降解的影响,确定了最佳工艺条件.在最佳工艺条件下,CODcr的去除率达到98%以上.     

N-杂环卡宾催化Stetter反应的研究进展

N-杂环卡宾作为一类新型的催化剂,已广泛应用于有机合成领域.综述了N-杂环卡宾催化Stetter反应的研究进展,包括分子间的Stetter反应、分子内的Stetter反应、聚合物支撑的Stetter反应、Stetter-Paal-Knorr反应及其在天然产物合成中的应用.     

Liquid-liquid-solid reactions: esterification of phenol with benzoyl chloride using a polymer-supported phase transfer catalyst

The reaction of phenol in alkaline solution and benzoyl chloride dissolved in toluene with a polymer-supported tri-n-butylphosphonium ion as phase transfer catalyst has been carried out in a slurry reactor. Mass transfer effects have been analysed with the standard theory of porous catalysts. The intrinsic reaction rate constant and diffusion coefficients within the porous polymer particle are estimated. The rate-limiting step has been identified.     

Rational approach to polymer-supported catalysts: synergy between catalytic reaction mechanism and polymer design

Supported catalysis is emerging as a cornerstone of transition metal catalysis, as environmental awareness necessitates "green" methodologies and transition metal resources become scarcer and more expensive. Although these supported systems are quite useful, especially in their capacity for transition metal catalyst recycling and recovery, higher activity and selectivity have been elusive compared with nonsupported catalysts. This Account describes recent developments in polymer-supported metal-salen complexes, which often surpass nonsupported analogues in catalytic activity and selectivity, demonstrating the effectiveness of a systematic, logical approach to designing supported catalysts from a detailed understanding of the catalytic reaction mechanism. Over the past few decades, a large number of transition metal complex catalysts have been supported on a variety of materials ranging from polymers to mesoporous silica. In particular, soluble polymer supports are advantageous because of the development of controlled and living polymerization methods that are tolerant to a wide variety of functional groups, including controlled radical polymerizations and ring-opening metathesis polymerization. These methods allow for tuning the density and structure of the catalyst sites along the polymer chain, thereby enabling the development of structure-property relationships between a catalyst and its polymer support. The fine-tuning of the catalyst-support interface, in combination with a detailed understanding of catalytic reaction mechanisms, not only permits the generation of reusable and recyclable polymer-supported catalysts but also facilitates the design and realization of supported catalysts that are significantly more active and selective than their nonsupported counterparts. These superior supported catalysts are accessible through the optimization of four basic variables in their design: (i) polymer backbone rigidity, (ii) the nature of the linker, (iii) catalyst site density, and (iv) the nature of the catalyst attachment. Herein, we describe the design of polymer supports tuned to enhance the catalytic activity or decrease, or even eliminate, decomposition pathways of salen-based transition metal catalysts that follow either a monometallic or a bimetallic reaction mechanism. These findings result in the creation of some of the most active and selective salen catalysts in the literature.     

Isomerization of 1-hexene catalyzed over polymer-supported RuCl2(PPh3)3

Polymer-supported ruthenium catalyst was prepared by anchoring dichlorotris(triphenylphosphine)ruthenium, RuCl₂(PPh₃)3, onto the phosphinated polystyrene bead. The polymer-supported RuCl₂(PPh₃)3 could be reused several times with only small loss of catalytic activity in the isomerization of 1-hexene. The activity rather increased during the few initial runs. In both homogeneous and heterogenized catalysts, an induction period was required to initiate the isomerization. The catalyst efficiency was promoted in the mixture of good swelling solvent and potent hydrogen donor. Upon heterogenizing, the activity was reduced by a factor of 2.0-8.2.