A novel method for asymmetric synthesis of both enantiomers of α-substituted carboxylic acid derivatives from optically active 1-chlorovinyl p-tolyl sulfoxides and lithium ester enolates with 1,4-chiral induction from the sulfur chiral center

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from symmetrical ketones and (R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with lithium enolate of carboxylic acid tert-butyl esters gave optically active adducts having a substituent at the α-position with high 1,4-chiral induction from the sulfur chiral center in high yields. The adducts were converted to optically active esters and carboxylic acids having a chiral center at the α-position. When this addition reaction was carried out with the ester enolate generated from excess carboxylic acid tert-butyl ester with LDA in the presence of HMPA, the diastereomer of the adduct was obtained. By using the two reaction conditions for the generation of the ester enolates, a new method for asymmetric synthesis of both enantiomers of carboxylic acid derivatives having a substituent at the α-position from the one chiral source, (R)-(−)-chloromethyl p-tolyl sulfoxide, was realized.     

双金属氰化物催化二氧化碳与环氧丙烷聚合

研究了双金属氰化配合物(DMC)催化剂催化二氧化碳(CO2)与环氧丙烷(PO)的共聚及PO的均聚反应,考察了DMC催化剂的诱导现象。结果表明,共聚时DMC催化的诱导期比均聚短,尤其是在低CO2压力(1.0MPa)下更明显,诱导期由均聚时的45min缩短为共聚时的15min。共聚时诱导期随CO2压力升高而增加,当反应压力由1.0MPa升高至7.0MPa时,诱导期由15min增至40min。PO与CO2共聚时的引发现象不同于PO均聚:共聚引发时温度和压力突然异常升高并迅速降低至引发前的状态,而均聚引发时温度突然升高后逐渐下降。由此可知CO2能促进DMC催化剂的活化。     

不同催化剂对苯酚H2O2羟基化反应的比较

用苯酚、双氧水经羟基化反应合成邻、对苯二酚,在Fe2O3为催化剂的反应系统中,反应诱导期长,且反应剧烈;当以杂多酸盐或Fe/ZrO2为催化剂时,诱导期消失,且羟基化反应平稳。 反应的诱导期可能是由铁的氧化物转化为活性物种Fe3+和Fe2+的过程引起的;在杂多酸盐或Fe/ZrO2催化剂的反应体系中,羟基化反应可能发生在催化剂表面而使反应变得缓慢平稳,反应诱导期消失。     

基于p-6P异质诱导生长酞菁铜薄膜的NO2传感器

为实现室温下低浓度NO₂气体检测,制作了p-六联苯(p-6P)诱导层的酞菁铜有机薄膜传感器。利用原子力显微镜(AFM)研究了不同沉积速率下p-6P薄膜的生长规律,慢速沉积提供足够的分子扩散时间,利于薄膜横向生长,形成高度低、尺寸大的晶畴。在p-6P薄膜上生长了酞菁铜薄膜,可以清晰看到晶畴上酞菁铜薄膜的有序排列。利用X射线衍射(XRD)仪,阐明了p-6P对酞菁铜薄膜具有很好的诱导效应。通过对比不同沉积速率p-6P薄膜诱导的酞菁铜传感器性能,发现慢速沉积诱导层的酞菁铜器件有高的响应强度和低的回复时间。异质诱导生长的酞菁铜传感器响应强度是直接生长在二氧化硅上的酞菁铜传感器的2倍,回复时间是3.2 min,对浓度为1.0 × 10^-5的NO₂气体灵敏。     

Molecular mechanics-assisted crystal engineering of solid state photoreactions: application to the Yang photocyclization of α-1-norbornylacetophenone derivatives

Based on molecular mechanics, Yang photocyclization of α-1-norbornylacetophenone derivatives in the crystalline state was engineered through methylation adjacent to the carbonyl group, thus changing the conformation in the crystal and leading to enhanced diastereo- and enantioselectivity.     

A hybrid nanofluid analysis near a parabolic stretched surface

Two dimensional incompressible steady viscous nano-fluid flow with the impacts of heat generation and porous medium is examined numerically. For this objective Ti₆Al₄v are taken as nano-particles dispersed in different base fluids such as methanol, engine oil and water. Basically in this study we will compare three different nano-fluids to assess their flow behaviour and thermal performance. The flow model is developed under certain assumptions. The two dimensional non-linear PDEs are converted into non-linear ODEs with suitable transformation. The numerical procedure is adopted to find the results by using Bvp4c technique in MATLAB. Moreover, graphs are generated for various parameters against the temperature and velocity profiles. The fluid behaviour for different parameter is examined on velocity and temperature profile. It is depicted that for high values of volume fraction and curvature parameter nano-particles leads to high velocity and temperature profile. Moreover, velocity profile decreases for permeability parameter, while temperature profile enhances for heat generation parameter. The influence of Nusselt number and skin friction also assessed. The model of entropy generation is also presented.     

Poly(glycidyl methacrylate)‐grafted hydrophobic charge‐induction agarose resins with 5‐aminobenzimidazole as a functional ligand

Hydrophobic charge‐induction chromatography is a new technology for antibody purification. To improve antibody adsorption capacity of hydrophobic charge‐induction resins, new poly(glycidyl methacrylate)‐grafted hydrophobic charge‐induction resins with 5‐aminobenzimidazole as a functional ligand were prepared. Adsorption isotherms, kinetics, and dynamic binding behaviors of the poly(glycidyl methacrylate)‐grafted resins prepared were investigated using human immunoglobulin G as a model protein, and the effects of ligand density were discussed. At the moderate ligand density of 330 μmol/g, the saturated adsorption capacity and equilibrium constant reached the maximum of 140 mg/g and 25 mL/mg, respectively, which were both much higher than that of non‐grafted resin with same ligand. In addition, effective pore diffusivity and dynamic binding capacity of human immunoglobulin G onto the poly(glycidyl methacrylate)‐grafted resins also reached the maximum at the moderate ligand density of 330 μmol/g. Dynamic binding capacity at 10% breakthrough was as high as 76.3 mg/g when the linear velocity was 300 cm/h. The results indicated that the suitable polymer grafting combined with the control of ligand density would be a powerful tool to improve protein adsorption of resins, and new poly(glycidyl methacrylate)‐grafted hydrophobic charge‐induction resins have a promising potential for antibody purification applications.     

光诱导[2+2]环加成在有机合成中的应用

综述了烯烃、二烯、烯酮双键和烯烃的分子间或分子内光环加成,总结了过去二十五年在有机合成中的研究成果。     

Cr_2O_7~(2-)对B-Z振荡反应的影响及其分析应用

研究了Cr2O72-对B-Z化学振荡反应的影响.结果表明,Cr2O27-的加入明显改变该振荡反应的诱导期,且诱导期的改变值Δtin与所加入Cr2O72-的浓度有良好的线性关系,线性范围3.45×10-6~6.20×10-4mol·L-1,相关系数为0.9992,对Cr2O72-扰动B-Z振荡反应的机理进行了探讨.     

Solution Structure and Behavior of Benzophenone-based Achiral Bisphosphine Ligands in Noyori-Type Ru（Ⅱ）-Catalysts

We herein report on solution structural studies of Ru^Ⅱ catalysts （3a, 9） composed of achiral bisphosphine ligands （4, 8） and the enantiopure 1,2-diphenylethylenediamine （DPEN）. Complete chiral induction from enantiopure （R,R）-DPEN to achiral bisphosphine ligand 3a was observed in solution, with the complex adopting a single, stable and non-fluxional （even at 70 ℃） configuration. The coordination of the C=O moiety in 4 to the cationic Run center is considered to be of key importance in providing the higher thermodynamic and kinetic rotation barrier for the flexible bisphosphine ligand in the complex. The obtained enantioselectivity （91% enantiomeric excess） and sense of chiral induction in the hydrogenation of acetophenone were found to be solely dependent on the chirality of the 1,2-diamine. Consistent with the hydrogenation product, the （R,R）-DPEN induces a M-conformation （fight-handed） chirality for flexible phosphine ligand 4 in the complex, resulting in a 2,2-configuration about the Ru^Ⅱ center.