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排序方式: 共有471条查询结果,搜索用时 15 毫秒
81.
82.
In this paper, a method is proposed for the numerical solution of optimal control problems with terminal equality constraints. The multiplier method is employed to deal with the terminal equality constraints. It is shown that a sequence of control functions, which converges to the optimal control, is obtained by the alternate update of control functions and multipliers.The authors wish to thank Dr. N. Fujii for his most valuable comments and suggestions. 相似文献
83.
含甲巯咪唑杂环为端基的非环冠醚的合成 总被引:2,自引:0,他引:2
本文以甲巯咪唑杂环为新的端基,在相转移催化条件合成了五个开链冠醚,这些化合物均通过元素分析、UV、IR 、^1H和^13CNMR波谱鉴定. 相似文献
84.
Designed To React: Terminal Copper Nitrenes and Their Application in Catalytic C−H Aminations 下载免费PDF全文
Dr. Julian Moegling Dr. Alexander Hoffmann Fabian Thomas Nicole Orth Patricia Liebhäuser Dr. Ulrich Herber Robert Rampmaier Julia Stanek Dr. Gerhard Fink Prof. Dr. Ivana Ivanović‐Burmazović Prof. Dr. Sonja Herres‐Pawlis 《Angewandte Chemie (International ed. in English)》2018,57(29):9154-9159
Heteroscorpionate ligands of the bis(pyrazolyl)methane family have been applied in the stabilisation of terminal copper tosyl nitrenes. These species are highly active intermediates in the copper‐catalysed direct C?H amination and nitrene transfer. Novel perfluoroalkyl‐pyrazolyl‐ and pyridinyl‐containing ligands were synthesized to coordinate to a reactive copper nitrene centre. Four distinct copper tosyl nitrenes were prepared at low temperatures by the reaction with SO2tBuPhINTs and copper(I) acetonitrile complexes. Their stoichiometric reactivity has been elucidated regarding the imination of phosphines and the aziridination of styrenes. The formation and thermal decay of the copper nitrenes were investigated by UV/Vis spectroscopy of the highly coloured species. Additionally, the compounds were studied by cryo‐UHR‐ESI mass spectrometry and DFT calculations. In addition, a mild catalytic procedure has been developed where the copper nitrene precursors enable the C?H amination of cyclohexane and toluene and the aziridination of styrenes. 相似文献
85.
Joshua A. Buss Christine Cheng Prof. Theodor Agapie 《Angewandte Chemie (International ed. in English)》2018,57(31):9670-9674
Toward nitrogen functionalization, reactive terminal transition metal nitrides with high d‐electron counts are of interest. A series of terminal MoIV nitride complexes were prepared within the context of exploring nitride/carbonyl coupling to cyanate. Reduction affords the first MoII nitrido complex, an early metal nitride with four valence d‐electrons. The binding mode of the para‐terphenyl diphosphine ancillary ligand changes to stabilize an electronic configuration with a high electron count and a formal M?N bond order of three. Even with an intact Mo≡N bond, this low‐valent nitrido complex proves to be highly reactive, readily undergoing N‐atom transfer upon addition of CO, releasing cyanate anion. 相似文献
86.
本文以含有端基炔的芳硫醚为原料,碘苯二乙酯为氧化剂,氯化亚铜为催化剂,室温下反应30 min,合成了1,4-二(2-芳硫基苯基)-1,3-丁二炔化合物。通过1HNMR、13CNMR等对其进行了结构表征,并研究了其光学性质,以及作为紫外线吸收剂在紫外光固化涂料中的应用。结果表明:该类化合物能够有效吸收270~360 nm的紫外光,且光降解程度小,并具有与树脂、单体相容性好、无气味等特点。同时,合成的目标化合物在光固化过程中不参与自由基体系的固化,且增强了涂料及固化涂层的光稳定性,有益于紫外光固化涂料的存储,是一类具有发展前景的紫外光吸收剂。 相似文献
87.
88.
端羟基聚丁二烯和端羟基SBS遥爪聚合物的合成及表征 总被引:3,自引:0,他引:3
研究了一种以非极性烃为溶剂,α-甲基萘锂复合物为基体的双锂催化剂LM-T作为引发剂,在环已烷中使丁二烯或丁二烯/苯乙烯进行双活性阴离子聚合,用精制的环氧丙烷终止,合成了双端羟聚丁二烯(HTPB)和双端羟SBS(HTSBS)两种遥爪聚合物。研究结果表明,聚合物分子量和羟基含量可由催化剂用量调整,官能度达到或接近2。分子量分布由GPC测定,宽度指数D=1.4左右。聚合物微观结构通过IR和H-HMR测定,1.4-聚丁二烯含量达到75%左右。因此,HTPB和HTSBS是两种1.4含量较高、分子量分布较窄的离子型遥爪聚合物。 相似文献
89.
Kazuhiko Hashimoto Shin-Ichiro Imanishi Masahiko Okada Hiroshi Sumitomo 《Journal of polymer science. Part A, Polymer chemistry》1992,30(2):211-220
A novel AB-type block copolymer composed of dextran and polyamide sequences was prepared through the following two approaches. One is a coupling reaction of a terminal functional group introduced in the dextran chain with that in the polyamide chain, such as the reaction of an amine group with an acyllactam group or that of a lactone group with an amine group at the corresponding chain ends. The other is an anionic polymerization of a bicyclic lactam activated with a trimethylsilylated dextran derivative having an acyllactam end group. The latter procedure was found to be more effective for the preparation of the block copolymer having a high molecular weight polyamide sequence. 相似文献
90.
First report of a nano‐Cu2O‐catalyzed protocol for homo‐coupling reaction of terminal alkynes in water/ionic liquid medium 下载免费PDF全文
Bo‐Xiao Tang Xiao‐Niu Fang Ren‐Yun Kuang Jian‐Hong Wu Qiao Chen Shao‐Jun Hu Yi‐Lin Liu 《应用有机金属化学》2016,30(11):943-945
A new, efficient and green protocol for the nano‐Cu2O‐catalyzed homo‐coupling reaction of terminal alkynes has been developed, using water/ionic liquid as an environmentally friendly solvent. Moreover, the system also allows the synthesis of unsymmetric 1,3‐diynes by cross‐coupling of two different terminal alkynes. It is noteworthy that the nano‐Cu2O‐catalyzed methodology is a good supplement to copper catalyst for the Glaser‐type homo‐coupling reaction. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献