本文選題：聚乙二醇 + 氮氧自由基��； 參考：《河北科技大學(xué)》2017年碩士論文

【摘要】：在醇的選擇性催化氧化反應(yīng)中,2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)作為高效催化劑尤為引人注目。但是TEMPO價(jià)格昂貴,分子量小不易回收,難以循環(huán)再利用,實(shí)現(xiàn)TEMPO的固載化可以有效解決以上問題。本課題將含氮氧自由基結(jié)構(gòu)單元的聚(甲基丙烯酸-2,2,6,6-四甲基哌啶-1-氮氧自由基酯)(PTMA)負(fù)載在具有良好溶解性和相轉(zhuǎn)移特性的聚乙二醇(PEG)上,得到了兩親性的含氮氧自由基嵌段共聚物�？疾炝嗽撉抖喂簿畚镞x擇性催化氧化醇的催化性能,并研究了其鏈結(jié)構(gòu)對催化性能的影響。含氮氧自由基嵌段共聚物通過電子轉(zhuǎn)移活化再生催化劑原子轉(zhuǎn)移自由基聚合(ARGET ATRP)制得。首先利用2-溴異丁酰溴與PEG發(fā)生酯化反應(yīng),得到大分子引發(fā)劑;單體甲基丙烯酸2,2,6,6-四甲基哌啶醇酯(TMPM)由大分子引發(fā)劑引發(fā)ARGET ATRP反應(yīng)得到嵌段共聚物PEG-PTMPM;最后,3-氯過氧苯甲酸(m-CPBA)將PTMPM中的氨基氧化為氮氧自由基,制得含氮氧自由基嵌段共聚物。采用紅外光譜、紫外可見光譜、凝膠滲透色譜、透射電鏡等對含氮氧自由基嵌段共聚物進(jìn)行了表征。制備的嵌段共聚物(PEG-PTMA)具有結(jié)構(gòu)可控、分子量分布范圍窄的優(yōu)點(diǎn)。其中,甲基封端的聚乙二醇負(fù)載的兩嵌段共聚物(MPEG-PTMA)的分子量范圍從8700到17000,聚乙二醇負(fù)載的三嵌段共聚物(PTMA-PEG-PTMA)的分子量從11200到39000。分散指數(shù)在1.5左右。將制備的含氮氧自由基嵌段共聚物PEG-PTMA應(yīng)用到醇的選擇性催化氧化中,分別以次氯酸鈉(NaClO)和分子氧(O2)為氧化劑,研究了PEG-PTMA結(jié)構(gòu)對苯甲醇催化性能的影響。PEG-PTMA表現(xiàn)出良好的催化選擇性,未出現(xiàn)過度氧化現(xiàn)象。NaClO作氧化劑時(shí),MPEG2000和PEG2000負(fù)載的嵌段共聚物表現(xiàn)出極為突出的催化性能,二者的催化效果甚至超過了未負(fù)載的TEMPO。此外,嵌段共聚物PEG-PTMA對其它伯醇也有較好的催化氧化效果。分子氧作氧化劑時(shí),分別以N,N-二甲基甲酰胺(DMF)和乙腈/水為溶劑,研究了催化劑的催化性能。以DMF為溶劑時(shí),MPEG5000-PTMA的催化效果較好,其它嵌段共聚物PEG-PTMA的催化效果并不理想。在乙腈/水兩相溶劑條件下,MPEG2000負(fù)載的嵌段共聚物的催化效果要優(yōu)于TEMPO。通過簡單的沉淀和過濾步驟即可實(shí)現(xiàn)嵌段共聚物的回收,其循環(huán)使用性能良好。
[Abstract]:In the selective catalytic oxidation of alcohols, the catalytic activity of Tetramethylpiperidine-6-tetramethylpiperidine-1-oxygen free radical (TEMPO) is particularly attractive. However, TEMPO is expensive, low molecular weight is not easy to be recovered, and it is difficult to recycle. So, the above problems can be effectively solved by immobilization of TEMPO. In this paper, the poly (tetramethylpiperidine-1-nitroxyl ester) (PTMAA) with nitrogen-containing oxygen free radical structure unit was loaded on polyethylene glycol (PEG) with good solubility and phase transfer property. Amphiphilic block copolymers containing nitrogen and oxygen free radicals were obtained. The catalytic properties of the block copolymers for selective catalytic oxidation of alcohols were investigated and the effect of chain structure on the catalytic performance was studied. The nitrogen-containing oxygen radical block copolymers were prepared by atom transfer radical polymerization (ARGET ATRP). Firstly, 2-bromoisobutylol bromide was esterified with PEG to obtain macromolecular initiator. The block copolymers PEG-PTMPM were prepared by the ARGET ATRP reaction initiated by macromolecular initiators, and the N-oxygen radical block copolymers were prepared by oxidation of amino groups in PTMPM into nitroxyl radicals. The nitrogen-containing oxygen radical block copolymers were characterized by IR, UV-Vis, gel permeation chromatography and transmission electron microscope. The block copolymer PEG-PTMA has the advantages of controllable structure and narrow molecular weight distribution. The molecular weight of MPEG-PTMAs is from 8700 to 17000, and the molecular weight of PEG-PTMA-PEG-PTMAs is 11200 to 39000. The dispersion index was about 1.5. The nitrogen-containing oxygen radical block copolymer (PEG-PTMA) was applied to the selective catalytic oxidation of alcohols with sodium hypochlorite (NaClO) and molecular oxygen (O _ 2) as oxidants, respectively. The effect of PEG-PTMA structure on the catalytic performance of benzyl alcohol was studied. PEG-PTMA showed good catalytic selectivity, and the block copolymers supported on PEG2000 and MPEG2000 showed excellent catalytic performance when there was no excessive oxidation. The catalytic effect of the two was even higher than that of unsupported TEMPO. In addition, block copolymer PEG-PTMA also has good catalytic oxidation effect on other primary alcohols. The catalytic performance of the catalyst was studied using N- (N-dimethylformamide) and acetonitrile / water as solvents respectively when molecular oxygen was used as oxidant. When DMF was used as solvent, the catalytic effect of MPEG5000-PTMA was better than that of other block copolymers PEG-PTMA. The catalytic effect of block copolymers supported on MPEG2000 was better than that of TEMPO in acetonitrile / water two-phase solvent. The block copolymers can be recovered by simple precipitation and filtration, and the recycling performance of the block copolymers is good.
【學(xué)位授予單位】：河北科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O631.5;O643.36

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