Synthesis, characterization and activity of an imine ligand (imidazol-2-yl)-CH=N-CH2-n-Cp' and its transition metal complexes - дипломная работа | ИСТИНА – Интеллектуальная Система Тематического Исследования НАукометрических данных

Научный руководитель: Borzov Maxim V.
Автор: Zhang Chengping
Тип: Специалист
Организация, в которой проходила защита: College of Chemistry and Material Science, the North-West University of Xi’an, Taibai Bei Avenue 229, Xi’an 710069, Shaanxi Province, People’s Republic of China
Год защиты: 2012
Аннотация: Polyolefins are top important high-molecular compounds in industry, agriculture, daily life, and other fields. Technology of their production is based on transition metal catalysts including catalysis with organometallic compounds. Major domestic and foreign companies and institutions have invested into this area of research in order to develop the catalysts with high activity, high stability and low cost for olefin polymerization. As a class of novel catalysts for olefin polymerization, imine catalysts for olefin polymerization have recently come into a focus of current research. These novel catalysts can achieve the same molecular design as metallocene catalysts and have already demonstrated many advantages over the metallocene ones, for instance, due to their lower price. In imine catalysts catalytic systems for olefin polymerization, an imido-group adjacent to an iso- or heterocyclic aromatic moiety presents the most typical element of the catalyst design. As an aromatic ensemble, pyridine and pyrrole are the most popular ones. Our laboratory has been engaged m the study of imidazole-functionalized ligands constrained geometry complexes derived from them for many years. In this work, we attempted to ,develop a practical synthetic approach to ligands of general type (imidazol-2-yl)-CH=N-(CH2)n-Cp' and to complexes of Ti, Zr, Fe, Co, Ni or Ru based on them (Cp' denotes methylcyclopentadienyl, tert-butylcyclopentadienyl and fluorene-9-yl). At first, the synthesis of the imidazole side chain functionalized monocyclopentadienyl imine ligands including 6a, 6b and 6c was carried out. These ligands were prepared by the following scheme. A related Cp'- salt was reacted with 2-bromoethylamine hydrobromide at low temperature that after isolation afforded Cp'-(CH2)n-NH2 (5a-c) or its hydrochloride dependently on the isolation conditions. Compounds 5a-c were reacted with imidazole-2-carboxaldehyde that afforded the target products 6a-c. The structure of 5a-c and 6a-c was confirmed by GC-MS method and by 1H and 13C{1H} NMR spectroscopy. Complexes 5a-c and 6a-c are all new compounds. The second part of the work presents an attempt to utilize ligand 6c as the model one in the synthesis of bi-and tridentate mononuclear transition metal complexes. This attempt was performed in four ways. The first one involves deprotonation of 6c with n-butyllithium. This way prepared Li-salt 7c was reacted with titanium, zirconium, iron or nickel chlorides with expected formation of complexes (8c1-c4). The second way involved reaction of 6c directly with titanium or zirconium tetramides, that gave complexes (8c5-c7). The third method included a reaction of titanium or zirconium tetrachloride with 6c in presence of triethylamine in toluene, that gave related products 8c8-c9. The fourth method included a reaction of transition metal chlorides with 6c in methanol, that gave related products 8c10-c17. The complex 7c and 8c8 showed good results by 1H 13C{1H} NMR spectroscopy. Finally, we investigated the olefin polymerization activity of 8c8. The ethylene polymerization activity is morderate (1 x 10^4 g PE/(mol Ti·atm·h)) for 8c8 activated by MAO. The research in preparation of transition metal complexes derived from the ligands 6a-c is currently in progress in our research team.
Добавил в систему: Борзов Максим Владимирович

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Synthesis, characterization and activity of an imine ligand (imidazol-2-yl)-CH=N-CH2-n-Cp' and its transition metal complexesдипломная работа (Специалист)

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