气相色谱法手性拆分氯代和溴代环氧苯乙烷

用手性毛细管气相色谱法(使用2，6-戊基-3-丙基-γ-环糊精柱，Chiraldex G-PN)对3种溴代环氧苯乙烷和3种氯代环氧苯乙烷对映体进行了拆分,初步讨论了对映体在该手性毛细管柱上的保留行为,已用于此类化合物对映体过量值(ee值)的测定．     

苯乙烯不对称环氧化反应液的高效液相色谱法分析

建立了Salen-Mn(Ⅲ)催化苯乙烯不对称环氧化反应的手性高效液相色谱分析法。采用手性AD-H柱,以正己烷和异丙醇为流动相,207nm作为检测波长,成功分离测定了苯乙烯及其环氧化产物环氧苯乙烷对映异构体。通过实验求得苯乙烯及(R)/(S)-环氧苯乙烷的线性回归方程,其相关系数分别为0.9985、0.9997、0.9995;方法检测限分别为0.02、0.10和0.13μg/mL;该方法低、中、高三个浓度水平的回收率为100.2%~100.8%;相对标准偏差分别为0.86%、1.52%和1.80%。     

环糊精手性微反应器中苯乙烯的不对称环氧化反应

研究了酮与环糊精手性协同催化作用下,用非手性酮与过氧硫酸氢钾(商品名Oxone)原位产生的二氧杂环丙烷实现了对包合在环糊精手性微反应器中苯乙烯的不对称环氧化反应,考察了α-环糊精、β-环糊精、γ-环糊精与不同的酮协同催化反应效果,并对协同催化反应机理进行了探讨.结果表明,β-环糊精和甲基异丁基酮(MIBK)及Oxone原位形成的二氧杂环丙烷具有较好的协同催化作用;MIBK用量、碳酸氢钠用量、反应时间和温度等因素对反应产物的收率和对映体选择性有一定的影响.在优化条件下,环氧苯乙烷的ee值可达46%.     

气相色谱-质谱/选择离子监测法用于苯乙烯不对称环氧化反应的筛选（英文）

建立了苯乙烯不对称环氧化反应的气相色谱-质谱/选择离子监测(GC-MS/SIM)筛选方法。以乙苯为内标,利用GC-MS/SIM对苯乙烯环氧化反应样品进行分析,在选定的分析条件下完全分离并准确测定了苯乙烯和环氧苯乙烷对映异构体的含量,同时利用该方法对苯乙烯环氧化反应的正交试验进行了评估。该方法具有以下优点:高精密度(以RSD表示的精密度为12%~52%,n=5)、良好的线性关系(苯乙烯、(R)-环氧苯乙烷和(S)-环氧苯乙烷标准曲线的相关系数分别为0999 7、0993 2和0996 3)、低定量限(苯乙烯、(R)-环氧苯乙烷和(S)-环氧苯乙烷的定量限分别为13、11和07 mg/L)以及合理的回收率(982%~1082%)。该方法为苯乙烯及其同系物的不对称环氧化反应提供了一种新的分析测定途径。     

β-环糊精与质子化及非质子化环氧苯乙烷超分子体系的理论研究

采用分子动力学模拟和量子化学计算方法对β-CD-环氧苯乙烷和质子化的β-CD-环氧苯乙烷形成的超分子体系进行了理论研究. 结果表明, 质子化的环氧苯乙烷的苯基朝向β-CD的小口时体系最稳定, 此时主客体的相互吸引作用相对较大; 而对于非质子化的环氧苯乙烷, 虽然其苯基朝向β-CD的大口较稳定, 但由于主客体之间具有较大的排斥能, 最终得到的包结物仍可能以苯基朝向β-CD的小口为主. 电荷密度拓扑分析发现, 当苯基取向β-CD的小口方向时, 质子化以及非质子化的环氧苯乙烷都能与位于β-CD大口边沿的羟基形成氢键. 因此, 环氧苯乙烷在β-CD内相中的定位作用主要得益于诸如氢键以及偶极等较强的分子间相互作用.     

D-72磺酸树脂催化合成(±)2-苯基-2-烷氧基乙醇

利用磺酸树脂D-72催化环氧苯乙烷与醇加成反应,合成了5种(±)2-苯基-2-烷氧基乙醇。其结构经1H NMR,IR和GC-MS表征。催化剂可重复使用8次。     

甲烷单加氧酶的化学模拟: 酚氧双羧酸根桥联Fe~2(III)和 Mn~2(III)配合物合 成、表征及催化性能

合成表征了酚氧、双羧基桥联双组氨酸的手性双铁核配合物和双锰核配合物,研究了它们催化亚碘酰苯对烯烃的环氧化反应和对环烷烃的羟化反应。结果表明这种Fe~2(III)和Mn~2(III)配合物均是有效的甲烷单加氧酶(MMO)模型化合物,其中Fe~2配合物能较好地再现MMO的某些性质,如电子光谱等。Fe~2配合物催化苯乙烯环氧化反应生成环氧苯乙烷的产率为840%(以催化剂计),且R-(+)-构型对映体过量(e.e.)达45.4%。相庆的Mn~2配合物则以7080%产率给出环氧苯乙烷,R-(+)-构型对映体过量51.6%。Mn~2配合物还能够催化环己烯和环己烷的氧化反应,产物及其分布分别为环氧环己烷3880、环乙烯醇603、环己烯酮189和环己醇1053、环己酮639%(以催化剂计)。EPR研究表明MM=O是反应的活性中间体。     

甲烷单加氧酶的化学模拟: 酚氧双羧酸根桥联Fe~2(III)和 Mn~2(III)配合物合 成、表征及催化性能

合成表征了酚氧、双羧基桥联双组氨酸的手性双铁核配合物和双锰核配合物,研究了它们催化亚碘酰苯对烯烃的环氧化反应和对环烷烃的羟化反应。结果表明这种Fe~2(III)和Mn~2(III)配合物均是有效的甲烷单加氧酶(MMO)模型化合物,其中Fe~2配合物能较好地再现MMO的某些性质,如电子光谱等。Fe~2配合物催化苯乙烯环氧化反应生成环氧苯乙烷的产率为840%(以催化剂计),且R-(+)-构型对映体过量(e.e.)达45.4%。相庆的Mn~2配合物则以7080%产率给出环氧苯乙烷,R-(+)-构型对映体过量51.6%。Mn~2配合物还能够催化环己烯和环己烷的氧化反应,产物及其分布分别为环氧环己烷3880、环乙烯醇603、环己烯酮189和环己醇1053、环己酮639%(以催化剂计)。EPR研究表明MM=O是反应的活性中间体。     

溴醇法合成环氧苯乙烷的研究

研究了溴醇法合成环氧苯乙烷原料配比和添加催化剂对收率的影响,当ＮａＢｒ的添加量为化学反应计量时,在添加催化剂的最佳反应条件下,收率可达８０．６（含量９７．５％）,将ＮａＢｒ溶液回收套用３次,当苯乙烯加料量为１ｍｏｌ时,获得环氧苯乙烷平均收率为７２．５％（含量９２．７％）,ＮａＢｒ平均消耗量为０．４６ｍｏｌ。     

2-戊基-3-苯基-2,3-环氧丙醇对映体在手性柱上的拆分研究

采用多糖类手性固定相,建立2-戊基-3-苯基-2,3-环氧丙醇对映体的高效液相色谱(HPLC)手性分析方法。考察了手性柱类型、流动相组成、流速及柱温对2-戊基-3-苯基-2,3-环氧丙醇对映体拆分的影响。结果表明,以Chiralcel OD-H色谱柱(25×0.46cm,5μm)分离,采用正己烷-异丙醇(V/V,90∶10)作流动相,在流速为0.8 mL·min-1,柱温25℃,检测波长210nm的条件下,2-戊基-3-苯基-2,3-环氧丙醇对映体能达到基线分离,且具有较好的重复性和稳定性,可用于对映体的拆分及质量控制。该方法也适用于2-戊基-3-苯基-2,3-环氧丙醇类似物质的手性拆分。     

(d,d-二龙脑酰基甲烷)铁(Ⅲ)配合物催化苯乙烯不对称环氧化反应

 从天然樟脑的衍生物出发,用二异丙氨基溴化镁作为缩合剂,在温和的条件下合成了手性配体d,d-二龙脑酰基甲烷,然后将其与FeCl3络合,首次制备了(d,d-二龙脑酰基甲烷)铁(Ⅲ)配合物. 通过 1H NMR,IR和元素分析对配合物的结构进行了表征,并用它来催化苯乙烯在空气作用下的不对称环氧化反应,主要得到了S-苯基环氧乙烷. 考察了不同结构的醛、空气流量、催化剂用量和反应温度等因素对苯乙烯环氧化反应产物收率和光学ee值的影响. 结果表明,当醛为2-乙基丁醛,空气流量为12 ml/min,催化剂用量为2%和反应温度为30 ℃时,苯基环氧乙烷的收率和ee值最高,分别为89.7%和78.1%.     

Production of Enantiopure Chiral Epoxides with E. coli Expressing Styrene Monooxygenase

Styrene monooxygenases are a group of highly selective enzymes able to catalyse the epoxidation of alkenes to corresponding chiral epoxides in excellent enantiopurity. Chiral compounds containing oxirane ring or products of their hydrolysis represent key building blocks and precursors in organic synthesis in the pharmaceutical industry, and many of them are produced on an industrial scale. Two-component recombinant styrene monooxygenase (SMO) from Marinobacterium litorale was expressed as a fused protein (StyAL2StyB) in Escherichia coli BL21(DE3). By high cell density fermentation, 35 g_DCW/L of biomass with overexpressed SMO was produced. SMO exhibited excellent stability, broad substrate specificity, and enantioselectivity, as it remained active for months and converted a group of alkenes to corresponding chiral epoxides in high enantiomeric excess (˃95–99% ee). Optically pure (S)-4-chlorostyrene oxide, (S)-allylbenzene oxide, (2R,5R)-1,2:5,6-diepoxyhexane, 2-(3-bromopropyl)oxirane, and (S)-4-(oxiran-2-yl)butan-1-ol were prepared by whole-cell SMO.     

硫醚功能化离子液体固定纳米金粒子的制备及其催化性能

合成了一种新型的硫醚功能化离子液体(TFIL),以其为稳定剂在1-甲基-3-丁基咪唑六氟磷酸离子液体中制备了TFIL固定的纳米金粒子(GNP-TFIL)催化剂.采用红外光谱、紫外-可见光谱和透射电子显微镜等方法对GNP-TFIL催化剂进行了表征.结果表明,TFIL在固定纳米金粒子之后仍保持着离子液体的基本结构;纳米金粒子的分布均匀,粒径为2.0～3.6nm.GNP-TFIL催化剂对苯乙烯环氧化反应具有较高的催化活性,且可以重复使用.在45℃下反应6h时,苯乙烯的转化率和环氧苯乙烷的选择性分别可达100%和88.5%.     

Chiral Monolithic Absorbent Constructed by Optically Active Helical‐Substituted Polyacetylene and Graphene Oxide: Preparation and Chiral Absorption Capacity

Chiral monolithic absorbent is successfully constructed for the first time by using optically active helical‐substituted polyacetylene and graphene oxide (GO). The preparative strategy is facile and straightforward, in which chiral‐substituted acetylene monomer (Ma), cross‐linker (Mb), and alkynylated GO (Mc) undergo copolymerization to form the desired monolithic absorbent in quantitative yield. The resulting monoliths are characterized by circular dichroism, UV–vis absorption, scanning electron microscopy (SEM), FT‐IR, Raman, energy‐dispersive spectrometer (EDS), X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), XPS, and thermogravimetric analysis (TGA) techniques. The polymer chains derived from Ma form chiral helical structures and thus provide optical activity to the monoliths, while GO sheets contribute to the formation of porous structures. The porous structure enables the monolithic absorbents to demonstrate a large swelling ratio in organic solvents, and more remarkably, the helical polymer chains provide optical activity and further enantio‐differentiating absorption ability. The present study establishes an efficient and versatile methodology for preparing novel functional materials, in particular monolithic chiral materials based on substituted polyacetylene and GO.

     

手性双哌啶衍生物用于甲基三氧化铼催化烯烃不对称环氧化反应

以N-烷基-4-哌啶酮为原料,制备了几个手性双哌啶衍生物配体.以尿素-过氧化氢复合物(UHP)为氧化剂,甲醇为溶剂,将这些配体用于甲基三氧化铼(MTO)催化的前手性烯烃的环氧化反应,考察了各种反应参数对催化剂催化性能的影响.结果表明,手性双哌啶衍生物的加入可降低MTO的催化活性,但可提高环氧化物的选择性;这些配体对前手性烯烃的环氧化反应有较低的手性诱导作用,对映体过量值(ee值)只有4%-11%.讨论了对映选择性低的原因.     

环氧乙烷与苯乙烯两亲性聚合物的合成

Graft eopolymer eontaining poly(ethylene oxide)side chains on a polystyrene backbone were acrylamided. The amide groups in the copolymers were ionized by using potassium naphthalene, and grafting was achieved by utilizing the amide anions as initiator sites for the polymerization of ethylene oxide at 70℃. The graft copolymers was characterized with respect to molecule weight and composition using NMR, IR, GPC, and DSC. GPC result from the graft copolymer sample suggested a narrow size distribution.     

MCM-48固载手性salen Mn(III)催化苯乙烯环氧化反应

手性salenMn(III)化合物是非常有效的烯烃不对称环氧化催化剂[1],近年来对它的非均相化研究越来越受到大家的关注[2-4].以聚合物为载体固载salen Mn(III)化合物的研究已经取得了很大的进展,相对的无机载体的研究要少得多.本文首次将手性salen Mn(III)化合物固载到介孔分子筛MCM     

Chiral Phosphine Ligands Derived from Sugars. 14. Crystal Structure of Diphenyl(methyl 4',6'-O-benzylidene-3'-deoxy-α-D-altropyranoside-3-)phosphine Oxide

The crystal structure of the title compound, C26H27O6P, has been determined by single-crystal X-ray diffraction analysis. The crystal is orthorhombic with space group P212121, a=6.154(4), b=17.199(8), c=22.180(3)(A), V=2347.6(A)3, Dc=1.32 g/cm3, F(000)=984, μ=1.5cm-1, Z=4, and final R=0.075 and Rw=0.080 for 1417 reflections (I≥3σ(I)). The X-ray diffraction analysis revealed that the structure of the title compound s similar to that of its parent phosphine and the pyranose and 4, 6-O-benzylidene rings remain distorted chair conformations.     

Electrochemically Assisted Cycloaddition of Carbon Dioxide to Styrene Oxide on Copper/Carbon Hybrid Electrodes: Active Species and Reaction Mechanism

A novel electrochemically assisted cycloaddition process is proposed, in which highly efficient coupling of CO₂ with styrene oxide (SO) can be achieved to form styrene carbonate (SC) as a high-value-added product. A series of Cu catalysts with different morphologies and chemical states were fabricated on carbon paper (CP) by using in-situ electrodeposition, and the sample with nano-dendrimer structure was found to exhibit a relatively high activity of 74.8 % SC yield with 92.7 % SO conversion under gentle reaction conditions, thus showing its potential for practical applications. The relatively high electrochemically active surface area and charge transfer ability of dendrimer-like Cu benefited the electrochemical reaction. In particular, the Cu²⁺ species that were formed in situ during the reaction played a vital role in enhancing the activity and selectivity of the proposed Cu/CP hybrid catalyst. Cu²⁺ atoms served as active sites that can not only electrochemically activate CO₂ but also facilitate the ring opening of SO. Mechanistic analysis suggested that the reaction followed electrochemical and liquid-phase heterogeneous paths, which provide a new green and sustainable route for efficient utilization of CO₂ resources for fine chemical electrosynthesis.