새로운 전이금속 촉매합성과 이를 이용한 에틸렌/a-올레핀 공중합
Syntheses of OrthophenyleneBridged Cp/amido Titaniumcomplexes and their Ethylene/α-Olefin copolymerization
초록/요약
1. Organolithium compounds are powerful intermediates in the organic synthesis. It can be prepared either by a halo-lithium exchange reaction of haloarenes with commercially available n-, sec-, or tert-butyl lithiums or more atom- economically by regioseclective ortho-deprotonation of heteroatom substituted arene, which is called “ Directed ortho lithiation”. The ortho lithiation of N-alkylaniline derivatives and 2- R-1,2,3,4-tetrahydroquinoline derivatives may allow for a simple and efficient synthetic route for the o-phenylene bridged Cp/amide ligand system. Here we report the conditions that lead to ortho lithiation and its utilization in the facile construction of various titanium complexes. Several of them exhibit excellent catalytic performance in ethylene/1-octene copolymerization. Ortho lithiation is achieved by the treatment of tBuLi to the lithium carbamate compounds derived from Nalkylaniline derivatives and 2-R-1,2,3,4- tetrahydroquinolines (R=H, methyl, n-butyl, tert-butyl, and 6-tert-butoxyhexyl), which enables the facile construction of the ophenylene- bridged (Me₄C_(5), indenyl, or fluorenyl)/amido titanium complexes. The titanium complex derived from 2-methyltetrahydroquinoline exhibits higher activity, higher 1-octene incorporation, and higher molecular weight in ethylene/1-octene copolymerization than the standard CGC, [Me₂Si(η^(5)-Me₄C_(5))- (N^(t)Bu)]TiCl₂. 2. Addition of R'2PCl to anilines substituted with di- or trimethylcyclopentadienyl unit at ortho-position affords ortho-phenylene-bridged Me₂Cp or Me₃Cp/phosophinoamide ligands, 2-(RMe₂C_(5)H₂)C_(6)H₄NHPR'₂ (R = Me or H; R' = Ph, iPr, or Cyclohexyl). Successive addition of Ti(NMe₂)4 and Me₂SiCl₂ to the ligands affords the desired dichlorotitanium complexes, [2-(η^(5)-RMe₂C_(5)H)C_(6)H₄NPR'₂- κ2N,P]TiCl2 (R = H, R' = Ph, 9; R = Me, R' = Ph, 10; R = H, R' = iPr, 11; R = Me, R' = iPr, 12; R = H, R' = Cy, 13; R = Me, R' = Cy, 14). By using Zr(NMe₂)₄ instead of Ti(NMe₂)4, a zirconium complex, [2-(η^(5)-Me₃C_(5)H)C_(6)H₄NP(iPr)₄-κ²N,P]ZrCl₂ (15) is prepared. Molecular structures of 10, 14, and [2-(η^(5)-Me₂C_(5)H₂)C_(6)H₄NPPh₂- κN]Ti(NMe₂)₂ (16) were determined. The metric parameters determined on the X-ray crystallographic studies and the chemical shifts of the ^(31)P NMR signal indicate that the phosphorous atom coordinates to the titanium in the dichloro-complexes 9-15. The titanium and zirconium complexes show negligible activity in ethylene and ethylene/1-hexene (co)polymerization when activated with MAO or iBu₃Al/[Ph₃C][B(C_(6)F_(5))₄].
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Contents
Abstract
Chapter 1. CO2-Mediated ortho-Lithiation of N-Alkylanilines and Tetrahydroquinoline Derivatives and Its Use for the Facile Construction of Polymerization Catalysts
Chapter 2. Synthesis and Structures of o-Phenylene-Bridged Cp/Phosphinoamide Titanium Complexes
