有機鋁化物之胺陰離子-胺基雙牙配位基的電子效應及 其催化環己內酯開環聚合反應的研究

Abstract

一系列在甲苯胺陰離子上帶有不同取代基之甲苯胺陰離子-胺基雙牙配位基以(C2H5)2NC(CH3)2CCH3N(Ar) [Ar = p-methoxyphenyl, p-methylphenyl, Phenyl, p-fluorophenyl, p-chlorophenyl] 形式，以及甲苯胺陰離子-吡啶雙牙配位基以 (C5H5N) C(CH3)2NH(Ar) [Ar'= Phenyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl] 形式被成功地合成與鑑定。 這些衍生物呈現扭曲的四角錐構型並且可以在沒有任何輔助的起始劑情況下，有效地活化環己內酯的開環聚合反應。合成出的高分子聚合物，具有良好的分子量散佈趨勢。 除此之外，加入具有輔助效應的醇類起始劑，除了可以在更短時間內催化環己內酯的開環聚合反應，亦可以得到分子量分佈均勻的高分子聚合物。 本論文除了鑑定以及合成高分子聚合物以外，利用電子效應的調控以及Hammett plot來探討反應機構。 電子效應有效地反應在催化活性上，並得到OMe >CH3 > H > Cl近線性的Hammett plot。表示推電子的基團可以有效增強甲苯胺陰離子的親核能力並加快整體聚合的反應速率。 利用不同的技術可以達到鑑定的效果外，本論文結合了末端基分析法，利用光譜分析以及聚合結果的趨勢來進行反應機構的推論。

A numbers of organoaluminum complexes bearing nitrogen-donating bidentate ligands of amido-amine such as (C2H5)2NC(CH3)2CCH3N(Ar) [Ar = p-methoxyphenyl, p-methylphenyl, Phenyl, p-fluorophenyl, p-chlorophenyl, 2,6-diisopropylphenyl] and anilido-pyridine ligands with formula of (C5H5N)C(CH3)2NH(Ar') [Ar' = Phenyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl] are synthesized and characterized. These mononuclear complexes are found in distorted tetrahedral geometry. The aluminum complexes are able to activate the ring-opening polymerization(ROP) of ε-caprolactone without using activators in toluene. The resulting polyester products show comparable activity and acceptable molecular weights distribution. (Mw/Mn<2). With assistance of benzyl alcohol, ROP could undergo with acceptable activity and controlable molecular weight distribution (Mw/Mn <2). Mechanistic studies for such ROP reactions particularly in terms of ligand effect are thus investigated.