在交联聚苯乙烯微球表面实现苯基卟啉的同步合成与固载

以键合有对羟基苯甲醛(HBA)的交联聚苯乙烯(CPS)微球HBA-CPS、苯甲醛和吡咯为反应物, 采用Adler方法, 实现了苯基卟啉(PP)在CPS表面的同步合成与固载, 制得了固载有苯基卟啉的微球PP-CPS. 研究了卟啉同步合成与固载过程的影响因素, 同时进行了微球PP-CPS与钴盐的配合反应, 制备了固载有钴卟啉(CoP)的功能微球CoP-CPS, 初步考察了其对分子氧氧化乙苯的催化活性. 实验结果表明, 在苯基卟啉同步合成与固载的反应过程中, 催化剂的酸性与溶剂的极性是两个主要的影响因素, 使用强极性溶剂与pKa在2.8~3.4范围的酸, 微球PP-CPS表面的苯基卟啉固载量高. 微球CoP-CPS对分子氧氧化乙苯的反应具有明显的催化活性.     

在氯甲基化交联聚苯乙烯微球表面合成与固载手性金属-Salen配合物及其表征

氯甲基化交联聚苯乙烯(CMCPS)微球的氯甲基与苯甲醛衍生物2-羟基-3-甲氧基苯甲醛(HMBA)发生傅克烷基化反应,形成改性微球HMBA-CPS;微球HMBA-CPS与环己二胺发生席夫碱反应,形成键合Salen配基的微球Salen-CPS;最后,使之与锰盐发生配位螯合反应,制得了固载有手性Mn(Ⅲ)-Salen配合物的固体催化剂Mn(Ⅲ)Salen-CPS,分别采用红外光谱、紫外/可见吸收光谱及扫描电子显微镜对固体催化剂的结构与形貌进行了表征和观察。 研究了微球CMCPS与HMBA之间傅克烷基化反应的规律。 结果表明,以AlCl3为Lewis酸催化剂,使用二氯甲烷与硝基苯混合溶剂,可有效地实施CMCPS与HMBA的傅克烷基化反应,制得固体催化剂Mn(Ⅲ)Salen-CPS。 在V(CH2Cl2)∶V(NB)=10∶1的混合溶剂中,40 ℃下反应10 h,可制得氯甲基转化率近于51%的改性微球HMBA-CPS。 该制备途径具有简便、高效与快捷的特点。     

Chelating Properties of Salicylhydroxamic Acid-functionalized Polystyrene Resins and Its Application to Efficient Removal of Heavy Metal Ions from Aqueous Solutions

Salicylhydroxamic acid(SHA) was covalently bound onto crosslinked polystyrene spheres(CPSs) via the Friedel-Crafts alkylation reaction between chloromethylated CPSs and SHA in the presence of SnCl4 as the Lewis acid catalyst. The resulted SHA-CPSs possessed very strong chelating ability for heavy metal ions. In particular, the saturated adsorption amount of SHA-CPSs for Cu²⁺ ions could reach as high as 34.2 mg/g at 318 K. The chelating capability of SHA-CPSs towards heavy metal ions was pH and temperature dependent. SHA-CPSs also showed selective metal coordination with the chelating capacity decreasing in the order of Cu²⁺>Zn²⁺>>Pb²⁺. The adsorption isotherms conformed well to the Langmuir model, and the adsorption process was found to be entropy-driven and endothermic. Besides, SHA-CPSs possessed the excellent reusability.     

金属酞菁与高价金属盐或氧化物在乙苯液相催化氧化反应中的协同效应

金属络合物催化饱和烷烃的选择性催化氧化一直是有机合成中具有挑战性的课题之一.饱和烷烃的催化氧化可采用各种氧源,如PhIO、H2O2、有机过氧化物或次氯酸盐等[1,2],然而采用分子氧为氧源对烃类化合物进行选择性催化氧化一直是人们致力于解决的目标.利用分子氧为氧源实现饱和烷烃的选择性催化氧化大致可分为两条路线:(1)在共还原剂(H2,醛,抗坏血酸)存在下利用原位产生的氧化剂的催化氧化[3,4];(2)金属卟啉[5]、杂多酸[6]及其它催化剂对饱和烷烃的直接催化氧化.路线(1)需要消耗大量的共还原剂,实际上是对分子氧的间接利用,不具有明显的实…     

NHPI, CoSPc和TBAB催化的乙苯液-液非均相绿色氧化反应研究

以水为催化剂溶剂与原料乙苯组成液-液非均相体系,以NHPI结合CoSPc组成催化体系,在TBAB为相转移催化剂的作用下,对乙苯的氧化反应条件进行了研究.研究发现乙苯在该催化体系中的最佳氧化条件依次是:水油体积比为3∶1;n(TBAB)∶n(乙苯)=1∶40;n(NHPI)∶n(乙苯)=1∶10,n(NHPI)∶n(CoSPc)=24∶1,反应温度110℃,氧气压力0.75 MPa,搅拌速率350 rpm,反应时间0.5 h.在最佳反应条件下乙苯转化率为60.6%,苯乙酮的选择性为95.2%,1-苯乙醇的选择性为4.5%,产物总选择性达到了99.7%.在此基础上延长反应时间并不能提高乙苯的转化率,苯乙酮的选择性也会下降,研究发现NHPI的分解是乙苯转化率不随反应时间的延长而提高的原因,而苯乙酮的过度氧化为苯甲酸是产物选择性下降的原因.     

Friedel-Crafts酰基化法制备聚苯乙烯型阴离子交换树脂

提出了一种合成聚苯乙烯型阴离子交换树脂的新方法：通过Ｆｒｉｅｄｅｌ－Ｃｒａｆｔｓ酰基化反应在交联聚苯乙烯上引入乙酰基，然后经溴化、胺化反应制备阴离子交换树脂。该方法避免了使用氯甲醚等致癌物质，并消除了二次交联等副反应。讨论了溶剂，催化剂，试剂和反应温度及时间等因素对各步反应的影响。测定了产物的基本性能并对所得结果进行了讨论。     

A Perspective on Heterogeneous Catalysts for the Selective Oxidation of Alcohols

Selective oxidation of higher alcohols using heterogeneous catalysts is an important reaction in the synthesis of fine chemicals with added value. Though the process for primary alcohol oxidation is industrially established, there is still a lack of fundamental understanding considering the complexity of the catalysts and their dynamics under reaction conditions, especially when higher alcohols and liquid-phase reaction media are involved. Additionally, new materials should be developed offering higher activity, selectivity, and stability. This can be achieved by unraveling the structure–performance correlations of these catalysts under reaction conditions. In this regard, researchers are encouraged to develop more advanced characterization techniques to address the complex interplay between the solid surface, the dissolved reactants, and the solvent. In this mini-review, we report some of the most important approaches taken in the field and give a perspective on how to tackle the complex challenges for different approaches in alcohol oxidation while providing insight into the remaining challenges.     

聚合物微球固载的N-羟基邻苯二甲酰亚胺在分子氧氧化甲苯过程中的催化性能

以交联聚苯乙烯(CPS)微球为基质,经过几步大分子反应在微球表面合成与固载了N-羟基邻苯二甲酰亚胺(NHPI),形成固载有NHPI的聚合物微球CPS-NHPI。本文主要将CPS-NHPI与过渡金属盐组成共催化体系,用于分子氧氧化甲苯的反应,考察了该非均相催化剂的催化特性与催化氧化机理。结果表明,几种过渡金属盐中,Co(OAc)2的助催化效果最好;微球CPS-NHPI与Co(OAc)2所构成的共催化体系,在温和条件(80℃和常压氧气)下可有效地将甲苯深度氧化为苯甲酸,显现出高的催化活性(甲苯转化率达到57%)与优良的选择性(苯甲酸的选择性达到84%)。催化氧化反应遵循自由基链式反应机理。主催化剂CPS-NHPI固载的NHPI与助催化剂Co(OAc)2适宜的摩尔比为14∶1,主催化剂所含NHPI为底物的12(mol)%时,催化剂用量较为合适。固体催化剂CPS-NHPI具有良好的再循环使用性能。     

高分子担载水杨醛希夫碱钴配合物催化分子氧氧化环己烯性能研究

合成了聚苯乙烯担载的酪氨酸水杨醛希夫碱钴配合物，并研究了该高分子金属配合物对分子氧氧化环己烯的催化性能．探讨了反应温度、添加剂及反应时间对环己烯转化率和产物选择性的影响．结果表明，70℃时，以微量醋酸为添加剂，在催化剂的催化作用下，以常压氧气氧化环己烯，得到烯丙基位的氧化产物环己烯醇、环己烯酮和中间产物环己烯过氧化氢．催化剂经五次循环使用仍具有较高的催化活性．环己烯在该高分子配合物作用下的催化氧化遵循一个自由基反应历程，与经典的Haber-Weiss历程相一致．     

固载化N,N-双齿席夫碱型氧钒(Ⅳ) 配合物的制备 及其在分子氧氧化乙苯中的催化作用

以交联聚苯乙烯(CPS)微球为初始物质,通过大分子反应,制备了键合有苯甲醛(BA)的聚合物微球BA-CPS,又以3-氨基吡啶(AP)为试剂,使微球BA-CPS与之发生席夫碱反应,制得了键合有N,N-双齿席夫碱配基的微球BAAP-CPS;然后使微球BAAP-CPS与硫酸氧钒发生配位螯合反应,成功制备了固载有N,N-双齿席夫碱型氧钒(Ⅳ)配合物的微球CPS-[VO(BAAP)2].用红外光谱(FTIR)和固体紫外吸收光谱等手段对微球CPS-[VO(BAAP)2]的化学结构进行了表征.将微球CPS-[VO(BAAP)2]用于乙苯的分子氧催化氧化过程,考察了其催化活性及主要因素对乙苯催化氧化反应的影响,探索研究了催化反应机理.实验结果表明,在分子氧氧化乙苯的反应中,微球CPS-[VO(BAAP)2]具有很高的催化活性和优良的催化选择性,可将乙苯高效地(45%的转化率)转化为单一产物苯乙酮.氧化反应可能遵循自由基反应历程,乙苯侧烷基氢过氧化物可能是关键的中间物.适宜的反应温度为110℃,且体系中催化剂有一适宜用量.     

5,7-二溴-8-羟基喹啉锰配合物催化H_2O_2选择氧化乙苯

设计合成了5,7-二溴-8-羟基喹啉锰的四齿和六齿配合物(Q2MnⅡ和Q3MnⅢ),并用傅里叶变换红外(FT-IR)光谱对两个配合物进行了表征.以醋酸铵和醋酸为助剂,丙酮-水作溶剂,两个锰配合物在室温20℃下能高选择性催化双氧水氧化乙苯制苯乙酮的反应,Q3MnⅢ比Q2MnⅡ具有更高的催化活性和选择性.在优化的反应条件下,乙苯转化率达27%,苯乙酮的选择性95%;而且催化剂稳定性良好,可循环使用三次.     

在交联聚苯乙烯微球表面同步合成与固载吡啶基卟啉及固载化钴卟啉的催化氧化性能

先通过季铵化反应将吡啶甲醛(PyAL)基团键合于交联聚苯乙烯微球(CPS)表面,制得改性微球PyAL-CPS,再通过Adler反应,成功地实现了吡啶基卟啉(PyP)在CPS微球表面的同步合成与同载,制得功能微球PyP-CPS,它再与碘甲烷发生季铵化反应制成N-甲基吡啶基卟啉(MPyP)季铵盐,从而制得固载有阳离子卟啉的...     

环己烷氧化微孔催化剂的研究进展

环己烷氧化是化工生产中的重要反应之一,其氧化产物为重要的化工生产中间体,因此开发高效的环己烷氧化多相催化剂体系具有重要的理论意义和应用前景。本文综述了国内外环己烷选择氧化微孔催化剂的研究进展,分别对Y沸石、ZSM-5沸石及MOFs三大类微孔催化剂体系的组成及催化性能进行了介绍,最后展望了环己烷多相催化体系的发展趋势。     

Synthesis of Nitrogen-doped Carbon Supported Cerium Single Atom Catalyst by Ball Milling for Selective Oxidation of Ethylbenzene

Through screening Ce precursors and pyrolysis temperatures[Ce(acac)₃ as Ce precursors and pyrolysis at 900 °C], zeolitic imidazolate framework-8(ZIF-8) derived nitrogen-doped carbon supported cerium single atom catalyst(Ce₁/NC) is successfully prepared by ball milling method. The Ce₁/NC catalyst exhibits exceptional catalytic performance in the selective oxidation of saturated C―H bonds in aromatic compounds, e.g., 91% conversion and 99% selelctivity can be achieved in the oxidation of ethylbenzene to acetophenone under mild reaction conditions.     

合成乙苯ZSM—5催化剂的FT—IR研究

ZSM-5沸石由于具有独特结构,作为新型的择形催化剂广泛应用于石油化工催化反应中.人们普遍认为这些催化反应是由于沸石的酸中心引起的,尤其是B酸中心,因此对此做了较多的研究.我们选用不同反应时间,苯与乙烯气相烷基化合成乙苯ZSM-5催化剂,用吡啶吸附方法研究了ZSM-5催化剂的酸性,结合催化剂活性考察数据,得到了一些有意义的信息.     

Bringing Homogeneous Iron Catalysts on the Heterogeneous Side: Solutions for Immobilization

Noble metal catalysts currently dominate the landscape of chemical synthesis, but cheaper and less toxic derivatives are recently emerging as more sustainable solutions. Iron is among the possible alternative metals due to its biocompatibility and exceptional versatility. Nowadays, iron catalysts work essentially in homogeneous conditions, while heterogeneous catalysts would be better performing and more desirable systems for a broad industrial application. In this review, approaches for heterogenization of iron catalysts reported in the literature within the last two decades are summarized, and utility and critical points are discussed. The immobilization on silica of bis(arylimine)pyridyl iron complexes, good catalysts in the polymerization of olefins, is the first useful heterogeneous strategy described. Microporous molecular sieves also proved to be good iron catalyst carriers, able to provide confined geometries where olefin polymerization can occur. Same immobilizing supports (e.g., MCM-41 and MCM-48) are suitable for anchoring iron-based catalysts for styrene, cyclohexene and cyclohexane oxidation. Another excellent example is the anchoring to a Merrifield resin of an Fe^II-anthranilic acid complex, active in the catalytic reaction of urea with alcohols and amines for the synthesis of carbamates and N-substituted ureas, respectively. A SILP (Supported Ionic Liquid Phase) catalytic system has been successfully employed for the heterogenization of a chemoselective iron catalyst active in aldehyde hydrogenation. Finally, Fe^III ions supported on polyvinylpyridine grafted chitosan made a useful heterogeneous catalytic system for C–H bond activation.     

TiO_2助剂对乙苯脱氢催化剂性能的影响

研究了TiO_2助剂对乙苯脱氢催化剂的结构和其催化性能的影响以及对催化剂中铁钾尖晶石活性相形成的作用,并对催化剂的物理化学性质进行了表征.表征结果表明,引入适量的TiO_2能显著促进催化剂中活性相K_2Fe_(22)O_(34)的形成,减小CeO_2的晶粒尺寸,提高其在催化剂中的分散性;另一方面,添加助剂TiO_2后可以降低CeO_2和活性相K_2Fe_(22)O_(34)的还原温度,为反应提供更多的氧缺位和酸碱中心,提高了催化剂乙苯脱氢反应的活性.     

Copper Tetrahydrosalen Complex Encapsulated in Zeolite Y： an Effective Heterogeneous Catalyst for the Oxidation of Cycloalkanes

In the last decade, encapsulation of transition metal complexes in zeolites and related materials has been paid much attention, because this type of materials could serve as functional mimic enzymes, possessing both homogeneous-catalysis and heterogeneous…     

Phosphine-Functionalized Syndiotactic Polystyrenes: Synthesis and Application to Immobilization of Transition Metal Nanoparticle Catalysts

The precise control of monomer sequence and stereochemistry in copolymerization is of much interest and importance for the synthesis of high performance materials, but studies toward this goal have met with only limited success to date. The coordination polymerization of diphenylphosphinostyrene (p-StPPh₂ and o-StPPh₂) and its copolymerization with styrene (St) by (C₅Me₄SiMe₃)Sc(CH₂C₆H₄NMe₂-o)₂ have been achieved for the first time to afford a new series of phosphine functionalized syndiotactic polystyrene. By the design of the polymer structure, the copolymer of o-StPPh₂ and St (poly(o-StPPh₂-alt-St)-b-sPS) containing o-StPPh₂ and St atactic alternating copolymer block and syndiotactic polystyrene block (sPS) showed excellent thermal stability and chemical resistance. The simple combination of the triphenylphosphine and syndiotactic polystyrene realized the stable immobilization of metal nanoparticles to afford highly robust metal@poly(o-StPPh₂-alt-St)-b-sPS nanocatalysts at high temperature and various atmospheres. The Cu@poly(o-StPPh₂-alt-St)-b-sPS catalyst can serve as a highly efficient heterogeneous catalyst for the synthesis of quinoline derivatives by acceptorless dehydrogenative coupling of o-aminobenzylalcohol with ketones.