含苯氧基/氮杂环配体的过渡金属配合物的合成及催化烯烃聚合反应的研究

【作者】 陈凤太；

【导师】 金国新；

【作者基本信息】 复旦大学 ， 有机化学， 2007， 博士

【摘要】 本论文合成、表征了一系列含有苯氧基／氮杂环配体的前过渡金属钛、锆、钒和后过渡金属镍、铜等烯烃聚合催化剂，探讨了催化剂结构、铝金属比、聚合反应温度等对烯烃聚合的影响，较为系统地研究了这些配合物催化乙烯或降冰片烯聚合的反应行为，发现了几个具有高活性催化乙烯或降冰片烯聚合的新型烯烃聚合催化剂。利用介孔分子筛SBA-15为载体，对非桥联单茂金属催化剂进行了负载化的研究，比较了均相催化剂与负载化催化剂在催化活性，聚合物分子量和聚合物形态等方面的异同。1．以不对称苯氧基-噁唑配体合成出3个新型非桥联单茂钛烯烃聚合催化剂。在助催化剂MAO的作用下，它们具有高活性催化乙烯聚合的能力，最高活性达1.23×10⁶gPEmol^-1Tih^-1，同时得到单峰窄分子量分布的高分子量聚乙烯（M_w／M_n=1.3，10⁵-10⁶）。特别地，在苯氧基邻位上取代基（R₁）的体积大小对催化剂的聚合性质有明显的影响，相同条件下催化乙烯聚合活性按递降顺序为R₁=Me＞H＞^tBu，而聚合物分子量大小顺序则为H＞Me＞^tBu。2．负载3个非桥联单茂钛和单茂锆均相催化剂于介孔分子筛SBA-15上，将它们应用于催化乙烯聚合，制得了具有很高分子量（10⁶数量级）的纳米聚乙烯纤维。通过反应温度的调节，在钛负载催化剂催化聚合产物中成功地观察到聚乙烯纤维形态的变化。在锆催化剂纤维状聚合产物中虽然没有能够观察到类似的现象，但随反应温度的升高其催化活性一直在增大，在测量的温度范围内（20-100℃），没有达到极点，这对工业化应用是很有利的。3．以不对称苯氧基-咪唑配体合成出两个具有特别结构的镍（Ⅱ）和铜（Ⅱ）配合物，借助于MAO的活化，它们显示出很高的催化降冰片烯聚合的活性，尤其是镍催化剂展示了超高的催化能力，最高活性达到2.29×10⁸gPNBmol^-1Nih^-1。铜催化剂的催化活性也高达3.16×10⁵gPNBmol^-1Cuh^-1。无论镍催化剂还是铜催化剂，它们都是目前文献报道的同类降冰片烯加成聚合催化剂中活性最高者之一。所得聚合物分子量也很高，达到10⁶数量级。4．以二-苯并咪唑吡啶和二-苯并噁唑吡啶为配体制备了两个钒基配合物，较为系统地研究了它们催化乙烯聚合的性质。在助催化剂MAO活化下，它们都具有较高的催化乙烯聚合的活性，最高催化活性分别达到1.12×10⁶gPEmol^-1Vh^-1和2.36×10⁵gPEmol^-1Vh^-1。与通常钒基催化剂不同，在整个测量温度范围内（15-75℃），两者都保持较稳定的催化活性，这也说明此类催化剂具有很好的热稳定性。5．实验中得到了四个氧桥相联的双核或多核钛基配合物。配合物1-3含有双核钛金属中心，其中配合物1为双核离子型结构，两个钛原子配位环境不同，它们之间通过单氧桥相连；而配合物2中两个钛原子具有相同配位结构，它们之间则通过双氧桥相连；配合物3为C₂对称双核钛配合物，中间以单氧桥相连形成线型结构的分子；Ti₄O₄八元环构成了配合物4的四核单茂钛结构。更多还原

【Abstract】 In this dissertation, a series of new olefin polymerization catalysts, includingearly transition metal complexes, such as titanium, zirconium, vanadium, and latetransition metal complexes based on nickel or copper, have been synthesized andcharacterized, ten molecular structures of which have been confirmed by singlecrystal X-ray analyses. Mainly, catalytic activities of these complexes for ethyleneand norbornene were investigated. The effects of catalyst structures, polymerizationconditions such as Al/M molar ratio, reaction temperature and ethylene pressure onolefin polymerization behaviour have been discussed in detail. Moreover, thesignificant differences between homogeneous non-bridged half-metallocene catalystsand their corresponding supported catalysts on SBA-15 have also been compared bythe catalytic activities, molecular weights and morphologies of polymers. The fulldissertation was summarized as follows:1. Three half-sandwich titanium catalysts bearing non-symmetrical phenoxy-oxazole ligands have been synthesized. After activated by methylaluminoxane （MAO）,these catalytic precursors could polymerize ethylene with high catalytic activities upto 1.23×10⁶gPEmol^-1Tih^-1 and produce narrow, unimodal molecular weightsdistribution （MWD） and high molecular weight polymers（M_w/M_n=1-3, 10⁵-10⁶）.Herein, it is noteworthy that the steric bulk effect of the ortho substitued group （R₁） ofthe phenoxy-oxygen on catalytic activity and molecular weight of polymers issignificant. At the similar reaction condition, the catalytic activities rink in descendingorder R₁=Me＞H＞^tBu, however, the molecular weight in the order H＞Me＞^tBu.Further, immobilizing these kinds of catalysts on SBA-15, the nanofibrouspolyetnylene （diameter for 40-80nm） can be obtained, which possess higher molecularweitght （up to 2.90×10⁶） than that of homogeneous counterpart（9.38×10⁵）.2. The supported catalysts have been prepared by immobilizing the non-bridgedhalf-titanocene and zirconocene on mesoporous molecular sieve SBA-15, which cancatalyize the ethylene polymerization and successfully obtain the nano-polyethylenefibers with high molecular weights. The effect of the immobilized titanium orzirconium catalyst with different catalytic activity on polymerization reaction hasbeen exhibited by their polymerization behaviour. For supported titanium catalyst,different morphologic polyethylene fibers can be given via the modulation of reactiontemperature under definite condition. Analogous phenomena cannot be observed for supported zirconium catalyst, However, the catalytic activities have always increasedas the reaction temperature rises till 100℃.3. Two special formative nickel（Ⅱ） and copper （Ⅱ） complexes with non-symmetric phenoxy-imidazole ligands have been prepared and characterized. Thevery high catalytic activities for norbomene polymerization have been provided bythem at the activation of MAO. In particular, the superhigh catalytic activity can beacquired by nickel catalyst and the highest value is up to2.29×10⁸gPNBmol^-1Nih^-1.The moderate catalytic activity has also been produced by copper catalyst, the highestvalue for 3.16×10⁵ gPNBmol^-1Cuh^-1. This is one of catalysts possessing highestactivities for vinyl addition polymerization of norbomene in literatures reported. Inaddition, the molecular weights of all polymers are very high in grade 10⁶.4. The bis（benzimidazole） pyridine vanadium （Ⅲ） （1） and bis（benzoxazole）pyridine vanadium（Ⅲ） （2） complexes have been prepared and their ethylenepolymerization activities have been investigated in detail. The highest catalyticactivities is up to 1.12×10⁶gPEmol^-1Vh^-1 for 1 and 2.36×10⁵gPEmol^-1Vh^-1 for 2,respectively. Moreover, within the reach of whole detected temperature （15-75℃）,the steady catalytic activities can be maintained for them, indicating that this type ofcatalyst possesses very good thermal stability.5. Four binuclear or multinuclear titanium-based complexes withμ-oxygen-bridged linkage have been synthesized and characterized. The rich and colorfulstructural features have been analyzed.更多还原