Efficient Room‐Temperature Oxidation of Hydrocarbons Mediated by Tricopper Cluster Complexes with Different Ligands

Six tricopper cluster complexes of the type [Cu^ICu^ICu^I( L )]¹⁺ supported by a series of multidentate ligands ( L ) have been developed as oxidation catalysts. These complexes are capable of mediating the facile oxygen‐atom transfer to hydrocarbon substrates like cyclohexane, benzene, and styrene (C₆H₁₂, C₆H₆ and C₈H₈) upon activation by hydrogen peroxide at room temperature. The processes are catalytic with high turnover frequencies (TOF), efficiently oxidizing the substrates to their corresponding alcohols, aldehydes, and ketones in moderate to high yields. The catalysts are robust with turnover numbers (TON) limited only by the availability of hydrogen peroxide used to drive the catalytic turnover. The TON is independent of the substrate concentration and the TOF depends linearly on the hydrogen peroxide concentration when the oxidation of the substrate mediated by the activated tricopper complex is rapid. At low substrate concentrations, the catalytic system exhibits abortive cycling resulting from competing reduction of the activated catalyst by hydrogen peroxide. This behaviour of the system is consistent with activation of the tricopper complex by hydrogen peroxide to generate a strong oxidizing intermediate capable of a facile direct “oxygen‐atom” transfer to the substrate upon formation of a transient complex between the activated catalyst and the substrate. Some substrate specificity has also been noted by varying the ligand design. These properties of the tricopper catalyst are characteristic of many enzyme systems, such as cytochrome P450, which participate in biological oxidations.     

Biosynthesis of the Fungal Organophosphonate Fosfonochlorin Involves an Iron(II) and 2-(Oxo)glutarate Dependent Oxacyclase

The fungal metabolite Fosfonochlorin features a chloroacetyl moiety that is unusual within known phosphonate natural product biochemistry. Putative biosynthetic genes encoding Fosfonochlorin in Fusarium and Talaromyces spp. were investigated through reactions of encoded enzymes with synthetic substrates and isotope labelling studies. We show that the early biosynthetic steps for Fosfonochlorin involve the reduction of phosphonoacetaldehyde to form 2-hydroxyethylphosphonic acid, followed by oxidative intramolecular cyclization of the resulting alcohol to form (S)-epoxyethylphosphonic acid. The latter reaction is catalyzed by FfnD, a rare example of a non-heme iron/2-(oxo)glutarate dependent oxacyclase. In contrast, FfnD behaves as a more typical oxygenase with ethylphosphonic acid, producing (S)-1-hydroxyethylphosphonic acid. FfnD thus represents a new example of a ferryl generating enzyme that can suppress the typical oxygen rebound reaction that follows abstraction of a substrate hydrogen by a ferryl oxygen, thereby directing the substrate radical towards a fate other than hydroxylation.     

Oxovanadium(IV) Schiff Base Complexes Encapsulated in Zeolite-Y as Catalysts for the Liquid-Phase Hydroxylation of Phenol

Liquid-phase hydroxylation of phenol with H₂O₂ to a mixture of catechol and hydroquinone in acetonitrile has been reported using oxovanadium(IV) Schiff base complexes encapsulated in zeolite-Y as catalysts. Reaction conditions have been optimized by considering the concentration of substrate and oxidant, amount of catalyst, volume of solvent and temperature. Under the optimized reaction conditions, [VO(sal-1,3-pn)]-Y (H₂sal-1,3-pn = N,N'-bis(salicylidene)propane-1,3-diamine) has shown the highest conversion of 34.3% after 6 h, [VO(salen)]-Y (H₂salen = N,N'-bis(salicylidene)ethane-1,2-diamine) and [VO(saldien)]-Y (H₂saldien = N,N'-bis(salicylidene)- diethylenetriamine) have comparable catalytic activity (33% conversion) while [VO(sal-1,2-pn)]-Y (H₂sal-1,2-pn = N,N'-bis(salicylidene)propane-1,2-diamine) has the poorest performance (10.6% conversion). All these catalysts are more selective (90%) toward catechol formation except [VO(sal-1,3-pn)]-Y, which only gives 68% selectivity.     

3,5‐Dimethylpyrazolium Fluorochromate(VI)‐Catalysed Oxidation of Organic Substrates by Hydrogen Peroxide under Solvent‐Free Conditions

3,5‐Dimethylpyrazolium fluorochromate (VI), C₅H₈N₂H[CrO₃F], DmpzHFC , serves as an efficient catalyst for oxidation of primary, secondary and allylic alcohols to the corresponding carbonyl compounds using H₂O₂ at room temperature under solvent‐free conditions. Oxidation of methyl phenyl sulfides and triphenylphosphine were also carried out successfully.     

二安替比林－（2－甲氧基）苯基甲烷光度法测定钒

本文合成了二安替化林－（２－甲氧基）－苯基甲烷（ＤＡＯＭＭ）并用元素分析、红外分析对其进行了鉴定。在吐温２０和Ｍｎ（Ⅱ）存在下，ＤＡＯＭＭ与钒（Ｖ）反应，生成橙黄色产物，λｍａｘ＝４８０ｎｍ，摩尔吸收系数ε＝３．１×１０５Ｌ．ｃｍ－１、ｍｏｌ－１。０．５～４μｇＶ（ｖ）／２５ｍｌ符合比尔定律。用于中草药中痕量钒的侧定，结果满意。     

SiO2负载双氯基桥联双核Mo(V)催化剂合成、表征及其催化环己烯环氧化性能

合成了SiO2负载双氯基桥联双核Mo(V)催化剂,并用红外光谱、X-光电子能谱测定及UV-vis光谱等方法进行了结构表征.结果表明:SiO2负载双氯基桥联双核Mo(V)中金属Mo(V)离子以双齿配位形式与SiO2表面氧键合,双核Mo(V)间以μ-双氯基桥联.实验发现,其作为催化剂用于环己烯环氧化反应的活性组分是Mo(VI)而不是Mo(V).在反应过程中,经环氧化剂叔丁基过氧化氢(t-BuOOH)处理后,具有很高的催化活性和选择性;研究探讨了其催化环己烯环氧化的反应机理;建立了催化剂中Mo分析和环氧环己烷气相色谱分析新方法;在n(t-BuOOH)=0.1mol,n(C6H10) : n(t-BuOOH) = 3 : 1,溶剂5 mL,催化剂用量(以Mo计) ～0.0216 g,反应温度80℃,时间60min反应条件下,环氧环己烷收率(以t-BuOOH计)在99% 以上,质量分数～ 99.5 %(GC检测).催化剂循环使用5次后,未见活性明显下降,环氧环己烷收率(以t-BuOOH计)仍接近99%.     

焙烧态Ca-Mg-Al类水滑石的制备及其吸附As(V)的研究

实验合成了一种焙烧态Ca-Mg-Al类水滑石,通过吸附动力学、吸附热力学及pH值的影响实验研究其对As (V)的吸附性能;并通过X射线衍射(XRD)、比表面积及孔径(BET)、场发射扫面电子显微镜(FESEM)、傅里叶红外光谱(FTIR)和X射线光电子能谱(XPS)等测试对合成材料进行表征并分析其吸附机理.实验结果表明,焙烧态Ca-Mg-Al 类水滑石对As(V)具有较强的吸附能力,其最大吸附量为71.86 mg/g,其吸附行为较符合Freundlich吸附等温方程和准一级动力学方程,且在不同的pH值下均能保持较好的吸附能力.焙烧态Ca-Mg-Al 类水滑石吸附As(V)的吸附机理主要包括类水滑石晶体结构的重建以及其表面羟基官能团的络合作用.     

双甘麟催化氧化合成麟甘酸的研究

用高压反应釜考察了铂系催化剂在双甘磷（PMIDA）氧化合成麟甘酸（PMG）反应中的催化活性。在100 ℃、0.6MPa压力下,双甘麟转化率达100％，磷甘酸的选择性＞90％。探讨了温度、压力、反应时间及催化剂用量等对催化剂性能的影响。     

双水杨醛缩乙二胺合铜[Cu(Salen)]/O2催化氧化安息香

以72.8%的产率合成了双水杨醛缩乙二胺合铜配合物[Cu(Salen)],用正交试验法考察了该配合物对安息香的空气氧化反应的催化作用。实验发现,在水杨醛乙二胺合铜配合物的催化下,安息香经空气氧化生成苯偶酰的产率可达87.9%。     

Comparison of Two Solvent Extraction Systems for the Separation of V(V) and Cr(VI) from an Industrial Leaching Solution

Two solvent extraction systems for V (V) and Cr (VI) separation in leaching solution were investigated in order to select the suitable separation method for the disposing of chromium-bearing vanadium slag. The best/suitable system was determined by extraction yield (E_V,%) and the separation factor of V(V) and Cr(VI) (β_V/Cr). On the condition of 1:1 molar ratio of H⁺ to vanadium (V), the E_V values were 99.8% and 95.1%, while the β_V/Cr values were 546.58 and 29.53 using the two different systems, respectively. The extraction reactions for system 1 were determined by the slope method, and the chemical equilibrium constants were obtained.     

Spectroscopic and Catalytic Activity Studies of VO(Saloph) Complexes Encapsulated in Zeolite-Y and Al-MCM-41 Molecular Sieves

VO(Saloph) complexes, where Saloph = N,N-o-phenylenebis(salicylide naminato), have been encapsulated in microporous zeolite NaY and mesoporous Al-MCM-41 molecular sieves by the flexible ligand synthesis method. Upon encapsulation the coordination of VO(Saloph) changes from a square pyramidal to an octahedral geometry. Encapsulation and the pore size have marked effects on the trans-stilbene and styrene epoxidation activities of VO(Saloph), with tert-butylhydroperoxide as oxidant. The encapsulated complexes are more active (by three to five times) than the neat complexes. The encapsulated complexes could easily be separated from the products and the catalysts can be reused. VO(Saloph) complexes encapsulated in Al-MCM-41 are relatively more active than the zeolite-Y-encapsulated complexes. The relaxed geometry of VO(Saloph) and easy access of the active site to the substrate molecules are perhaps responsible for the higher activity of VO(Saloph) encapsulated in Al-MCM-41.     

Studies of adsorption properties of crosslinked chitosan for vanadium(V), tungsten(VI)

In this article, the adsorption properties of crosslinked chitosan (CCTS) for V(V) and W(VI) were studied. Experimental results showed the adsorption rates of CCTS for V(V) and W(VI) were closely related to the acidity of solution. The adsorption rates were 97% for V(V) at pH 4.0 and 96% for W(VI) at pH 4.5. The adsorption balance times, adsorption capacities, and adsorption mechanism were explored. This research is of significance for removal of V(V) and W(VI) in industrial wastewater and their preconcentration in trace analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1584–1588, 2004     

多氧取代环己烯酮(醇)衍生物的合成及表征

为寻找具有抗肿瘤活性的化合物,对天然的具有抗肿瘤活性的环己烯类化合物进行结构修饰和改造,设计合成了3个多氧取代环己烯酮(醇)类化合物,其结构均经过IR1、H NMR和HRMS表征。对化合物(3R,4S,5R)-1-苯甲酰氧亚甲基-3,4,5-三羟基-1-环己烯(7)的烯丙醇选择性氧化的条件进行了探索,最佳条件:活性MnO2为氧化剂,在苯中回流10 min,产率达到20.6%。     

Cross-coupling of C(sp)-H Bonds with Organometallic Reagents via Pd(II)/Pd(0) Catalysis**

Palladium-catalyzed C-H activation/C-C bond-forming reactions have emerged as a promising class of synthetic tools in organic chemistry. Among the many different means of forging C-C bonds using Pd-mediated C-H activation, a new horizon in this field is Pd(II)-catalyzed cross-coupling of C-H bonds with organometallic reagents via a Pd(II)/Pd(0) catalytic cycle. While this type of reaction has proven to be effective for the selective functionalization of aryl C(sp(2))-H bonds, the focus of this review is on Pd(II)-catalyzed C(sp(3))-H activation/C-C cross-coupling, a topic of particular importance because reactions of this type enable fundamentally new methods for bond construction. Since our laboratory's initial report on cross-coupling of C-H bonds in 2006, this area has expanded rapidly, and the unique ability of Pd(II) catalysts to cleave and functionalize alkyl C(sp(3))-H bonds has been exploited to develop protocols for forming an array of C(sp(3))-C(sp(2)) and C(sp(3))-C(sp(3)) bonds. Furthermore, enantioselective C(sp(3))-H activation/C-C cross-coupling has been achieved through the use of chiral amino acid-derived ligands, offering a novel technique for producing enantioenriched molecules. Although this nascent field remains at an early stage of development, further investigations hold the potential to revolutionalize the way in which chiral molecules are synthesized in industrial and academic laboratories.     

硅烷偶联剂改性硅藻土及其去除水中As(Ⅴ)的研究

以硅藻土为基体,γ-氨丙基三甲氧基硅烷(APES)作为改性剂,对硅藻土表面进行修饰,制备了针对As(V)吸附材料.采用单因素试验法,得到改性的最佳条件为:硅藻土为3 g,γ-氨丙基三甲氧基硅烷(APES)为4 mL,pH值为11,反应时间6 h,反应温度为30 ℃,该材料对As(V)的去除率可以达到87.11%.用扫描电镜(SEM)和傅里叶红外光谱仪(FT-IR)对材料进行表征,显示:改性前后的硅藻整体结构不发生变化;硅藻经改性后活性羟基峰消失,表面生成新的-NH2吸收峰.用Freundlich吸附模型能更好的描述吸附行为,吸附过程符合准二级动力学方程.     

Separation of Simulated Mixed Mo(VI) and V(V) From HNO3 and HCl Solutions by Selective Extraction and Stripping with Tri-N-Butyl Phosphate as Extractant

Equilibrium study was carried out to determine the optimum conditions required for Mo(VI) extraction from HNO₃ solutions and subsequently, simulated mixed Mo(VI), and V(V) were extracted from HNO₃ (pH = 1.0) and 6.0 mol L^?1 HCl solutions with TBP dissolved in n-hexane. The variation of pH (selective extraction) and selective stripping were investigated as methods of separation of Mo(VI) and V(V). The latter method was found inefficient for separations from HNO₃ solutions (pH = 1.0) except supplemented with selective stripping (back-extraction with 2.0 mol L^?1 H₂SO₄/14.5 mol L^?1 NH₄OH). While from 6.0 mol L^?1 HCl, selective stripping was adequate to quantitatively strip in turns the Mo(VI) and V(V) co-extracted into the TBP phase. About 100% of the co-extracted V(V) from the HCl medium was stripped in a two-stage process, in contrast to a single-stage required for Mo(VI) of the same result. The selective stripping method was found to be better because an initial appreciable co-extraction had occurred prior to stripping separation. Based on analytical and spectra data, the extracted complexes from HNO₃ and HCl media were formulated as ((MoO₂)_7–8n(VO₂)_2n · (NO₃)₁₆) ^(16–18)n- · m TBP (where n>m) and (MoO₂Cl₂ · VO₂ Cl) · xTBP, respectively.     

用于控制CO2氨法捕获过程中NH3逸出的选择性催化氧化（SCO）催化剂

利用NH3选择性催化氧化(NH3-SCO)方法控制电站CO2氨法捕获过程中的NH3逸出具有良好的应用前景,但用于该方法的催化剂应该具有高低温活性、高N2选择性高、长耐久性和低成本等特性。为推进NH3-SCO技术的实用化进程,本文在文献研究的基础上,总结了几种NH3-SCO催化剂的组成、不同催化剂和不同运行条件下NH3-SCO的特性和机理以及能提升催化效果的助剂,以期为探索合适的新型催化剂和新型反应器结构提供参考。文献研究表明,Ag/Al2O3是一种具有良好低温活性的NH3-SCO催化剂,但需具备Fe-ZSM-5所具有的高N2选择性,同时,还可以考虑利用一些物质如Ce可以用来进一步提升Ag/Al2O3的低温活性。     

Polyoxometalate (POM) Oxidation of Milled Wood Lignin (MWL)

Abstract

The chemical structural changes of Lodgepole pine milled wood lignin (MWL) before and after polyoxometalate (POM) oxidation were investigated using gel permeation chromatography (GPC), Fourier Transform infrared spectroscopy (FTIR), and solution‐state nuclear magnetic resonance spectroscopy (NMR). ¹³C NMR spectroscopic data revealed an approximately 28% decrease in α‐OH/β‐O‐4 inter‐unit linkages after POM treatment. This was accompanied by an increase in carbonyl and phenolic hydroxyl content. These results suggest POM oxidation involved side chain (such as α‐OH/β‐O‐4) oxidation and/or degradation of some of the inter‐unit linkages. Quantitative ¹³C NMR along with GPC analysis revealed an increase in the degree of condensation of the MWL as a result of POM treatment, suggesting radical coupling as a major reaction pathway.     

高度氧化法的特性及其在废水处理中的应用

论述了新兴化学氧化法－－高度氧化法（ＡＰＯ法）的氧化能力、反应选择性和氧化效率,并以苯酚和２,４－二氯苯酚为目标污染物进行了试验。结果表明：ＡＰＯ法比普通化学氧化法氧化效率高,无反应选择性,反应彻底,是一种处理含难降解有机污染物废水的高争化方法,值得推广。