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391.
Prof. Dr. Mikael Bols Victor Friis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(29):e202200564
The kinetics of the reaction of perbenzyl α-cyclodextrin was studied varying the concentration of DIBAL and substrate, and the temperature. The initial debenzylation was found to be 1st order in substrate and follow the relationship 0.0675+0.179[DIBAL]2 with respect to the concentration of DIBAL. The second and the third debenzylation which led to the 3A,6A,6D-triol (Lings triol) were both found to be 1st order in substrate concentration and zero order in DIBAL concentration. Longer reaction times with DIBAL in high concentration gave further debenzylation to comparatively complex mixtures containing the 2B,3A,6A,6D-tetrol and the 3A,6A,6C,6D-tetrol. In contrast reaction at 0.1 M DIBAL gave the symmetrical 3A,6A,3D,6D-tetrol (Lings tetrol) in 60 % yield. The effect of chlorine or methyl substitution of the phenyl groups of perbenzyl α-cyclodextrin was also investigated. Per 4-chlorobenzyl slowed down the reaction with DIBAL, while 4-methylbenzyl increased the reaction rate, but still gave the corresponding 6 A-monool or 6A,6D-diol products. A Hammett reaction constant of −4.9 was found for the first debenzylation showing a high degree of positive charge in the transition state. The per(2,4-dichlorobenzyl)-α-cyclodextrin-derivative was completely resistant to DIBAL, however upon addition of trimethyl aluminium this derivative also reacted to give the 6A,6D-diol product. 相似文献
392.
采用以太阳光为能源、半导体材料为催化剂的催化体系将胺类化合物转化为相应的亚胺类化合物的方法是一种理想的有机合成手段.为了探索这类反应更温和的反应条件及更清晰的反应机理,本工作以NH2-MIL-68(In)和硫脲为前驱体制备了In2S3分级纳米管,并进一步采用热离子交换的方法制备了In2S3/CdIn2S4纳米管复合材料.采用粉末X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、紫外-可见漫反射光谱(UV-vis DRS)、荧光光谱(PL)和电化学阻抗谱(EIS)等分析手段对催化剂的结构、形貌、光电性质等进行了表征.实验结果显示,In2S3和CdIn2S4间有效异质结降低了In2S3/CdIn2S4复合材料的光生载流子的复合效率,使In2S3/CdIn2S4具有较高的催化活性.催化剂的活性测试实验结果证明,In2S3和CdIn2S4间有效异质结和分级结构间的协同作用使In2S3/CdIn2S4纳米复合材料可作为一种有效的光催化剂催化氧化苯甲胺的偶联反应.活性物种捕获实验证明该反应是由光生空穴(h+)引发的.此外,此研究发现苯甲胺的氧化偶联反应同时可以在氧气或氮气条件下发生,打破了该反应必须要有氧气参与的束缚,拓展了苯甲胺氧化偶联反应的适用范围.循环实验结果显示,催化剂可循环使用五次,证明该催化剂具有较好的稳定性. 相似文献
393.
Cecilia C. Hall Cecelia A. Rivera Timothy P. Lodge 《Journal of polymer science. Part A, Polymer chemistry》2019,57(3):281-287
A reflection cloud point technique allows for rapid screening of light‐dependent phase separation temperatures of thermo‐ and photoresponsive polymer/ionic liquid solutions as a function of sample thickness, molecular weight, and copolymer composition. We systematically investigate the lower critical solution temperature (LCST) phase behavior of poly(benzyl methacrylate‐stat‐(4‐phenylazophenyl methacrylate)). Under UV light, the photoresponsive azobenzene‐based repeat unit becomes more polar as the cis form dominates, increasing its solubility in the ionic liquids 1‐ethyl‐3‐methyl imidazolium and 1‐butyl‐3‐methyl imidazolium bis(trifluoromethanesulfonyl)imide. This light‐dependent polarity change leads to two phase separation temperatures, depending on the illumination wavelength. Under visible light, which drives the azobenzene moiety into the trans ground state, the LCST shows no sample thickness dependence. Under UV light, however, sample thickness plays a significant role. Samples of around 1 mm thickness show no apparent difference under UV and visible light, whereas thinner samples show an increasing difference between the phase separation temperatures with decreasing sample thickness. Neither phase separation temperature exhibits a significant dependence on molecular weight. Increasing the photoresponsive monomer content did not lead to an increase in the difference between the phase separation temperatures at fixed thickness, due to a concomitant increase in UV light absorbed at the sample surface. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 281–287 相似文献
394.
Dr. Ze Yang Weiwei Cui Dr. Kun Wang Yuwei Song Dr. Fuhua Zhao Dr. Ning Wang Prof. Yunze Long Prof. Huanlei Wang Prof. Changshui Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(22):5643-5647
Here, a new approach to further improve graphdiyne (GDY) based materials by using benzyl disulfide (BDS) as the sulfur source is demonstrated. The S radicals, generated from the homolysis of BDS, can react with the acetylenic bonds and be well confined in the triangle-like pores of GDY, forming S-GDY. The as-prepared S-GDY, which possesses numerous heteroatom defects and active sites, is suitable for applications in many electronic devices, such as lithium ion batteries (LIBs). As expected, the assembled LIBs based on S-GDY displayed improved electrochemical properties, including larger capacity and superior rate capability. 相似文献
395.
研究了一种将苯甲醇直接氧化成苯甲醛的催化体系:氯化金属卟啉/离子液体/氧化剂(MTPPCl/ILs/[O]),考察了该体系反应过程中温度、氯化金属卟啉、氧化剂、轴向配体和离子液体的种类等因素对反应收率的影响。结果表明,催化剂氯化锰卟啉、溶剂1-丁基-3-甲基咪唑硫酸氢盐离子液体、氧化剂过硫酸钾组成的催化体系MnTPPCl/[Bmim]HSO4/K2S2O8在苯甲醇直接催化氧化成苯甲醛的反应中表现出很好的活性(99%)和选择性(99%),且该体系避免了使用传统的有机溶剂,可重复多次使用。 相似文献
396.
397.
Hélène PellissierAuthor Vitae 《Tetrahedron》2011,67(21):3769-3802
398.
A. Ebrahimi M. Habibi Khorassani M. Doosti 《International journal of quantum chemistry》2012,112(3):873-881
The effects of solvent on SN2 reaction between some substituted benzyl chlorides and chloride ion have been investigated by DFT and ab initio methods using the polarizabale continuum model. The activation energies are higher in the solution media relative to the gas phase and grow by the increase in the dielectric constant of solvent. The complexation energies in solution media are smaller than those in the gas phase and reduce with increasing the dielectric constant. The energy data are in good agreement with the geometrical parameters and substituent constants. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
399.
Ramesh Naik 《合成通讯》2013,43(2):165-168
A mixture of DMSO, NaNO2, and 49% HBr is found to oxidize primary benzyl amines to benzoic acids at 100°C. 相似文献
400.
A general, simple, and environmentally friendly method for the direct amination of secondary benzyl alcohols with amides or 4-nitroaniline is described. This method has been applied to a variety of substrates, and the reaction proceeded smoothly at room temperature under solvent-free conditions. CbzNH2 was proved to be very useful in the direct preparation of the benzylic amines from corresponding alcohols.