利用鹼在空氣常溫下氧化裂解木質素 β-O-4 模型分子 暨 以 1H DOSY NMR 探討銅(I)催化碳-氮偶合反應的機制

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/74003

Title:	利用鹼在空氣常溫下氧化裂解木質素 β-O-4 模型分子暨以 1H DOSY NMR 探討銅(I)催化碳-氮偶合反應的機制
Authors:	高雨婷;TING, KAO YU
Contributors:	化學學系
Keywords:	木質素
Date:	2017-08-04
Issue Date:	2017-10-27 12:58:39 (UTC+8)
Publisher:	國立中央大學
Abstract:	在本篇文章中，我將會分為木質素裂解以及碳氮偶合反應兩個部分介紹。第一部分：全球每年有數千億噸的植物廢棄物產生，科學家們嘗試將他們分離、精煉，以賦予這些植物廢棄物更多的效益，而生物質當中的木質素，因為結構上含有非常多苯環，我們期待可以找出有效裂解木質素的方法，能將它由大分子裂解成可利用的小分子。關於木質素的研究已經有許多文獻，但條件因為需要過度金屬催化劑參與、高溫還需要氧化劑等添加物，使我們覺得木質素裂解的反應條件可以再優化。為了釐清木質素裂解的機制以及找出更好的條件，許多科學家先從分子較小的木質素模型分子著手，並由於木質素中含量最多的鍵結為β-O-4，所以著重在研究含有β-O-4鍵結的模型分子，此模型分子通常會帶有二級醇官能基，將此二級醇先進行氧化再斷裂，是裂解木質素的策略之一。我們選擇氧化過的β-O-4模型分子，找出許多溫和的反應條件，利用溶劑的改變，在室溫下，不需要添加氧化劑，就能僅用當量的鹼將氧化過的木質素模型分子氧化斷裂，或者能選用醇類溶劑，利用加溫或加入對環境較無害並且成本較低的二價銅鹽類催化劑，也能讓反應達到很好的效果，最後推論出此反應條件的反應機制，並以理論計算佐證。第二部分：碳氮偶合催化反應是有機合成上十分重要的一環，其中，關於利用銅催化將芳香滷化物以及胺類偶合的反應已經有非常多研究，但其中的反應機制尚未完全明朗，在這裡我們針對HNPh2 / iodotoluene / CuI /1,10-phenanthroline的偶合系統，介紹新找到的關於碳氮偶合反應機制的證據，以及分別利用銅一價以及銅二價催化劑進行反應，比較他們的反應性差異。 ;This article is divided into two parts： The first part： There are hundreds of billion tons of plant wastes generated every year. Scientists tried to separeate and refine to make those wastes more benefit. Lignin is one part of lignocellulose and consisted of aromatics. We expected to find out a effective way to cleave lignin into many different small molecules and then separate them very well. In order to clarify the mechanism of lignin cleavage and to find out the better conditions, many scientists using lignin model compounds in the cleavage reaction at first, especially beta-o-4 model compounds because beta-o-4 linkage is the most abundant bonds in lignin. Ketone-form beta-o-4 which the secondary alchohol functional group was oxidized can promote the cleavage of beta-o-4 bond, so starting our research on this kind model compounds, we found out many mild conditions to break them down to small molecules. We developed a new approch to break down beta-o-4 model compounds to phenol and benzoic acid with only equivalents of KOH under aerobic condition in acetonitrile at room temperature. We also found that reactions could work effectively by heating up the temperature of reaction to reflux temperature or adding Cu(II) catalyst. Finally, we proposed the mechnism of the reaction and proved by theoretical calculations. The second part： The reaction of C-N cross coupling is play a important part of organic synthesis. Among them, there had already many researches on the C-N cross coupling by copper-catalyzed between aryl halides and amines, but the reaction mechanism is not yet clear. In this article, we presented the new evidence of the mechanism of the C-N coupling reaction for the coupling system of HNPh2 / iodotoluene / CuI / 1,10-phenanthroline, and reacted with copper(I) and copper(II) catalysts respectively to compare their differences in reactivity.
Appears in Collections:	[Graduate Institute of Chemistry] Electronic Thesis & Dissertation

Files in This Item:

File	Description	Size	Format
index.html		0Kb	HTML	326	View/Open

社群 sharing

Loading...