PMMA-PTMA的合成及其催化分子氧氧化苯甲醇
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摘要
通过电子转移活化再生催化剂原子转移自由基聚合法(ARGET ATRP)依次聚合单体甲基丙烯酸甲酯(MMA)和甲基丙烯酸-2,2,6,6-四甲基-4-哌啶基酯(TMPM),制得嵌段共聚物PMMA-PTMPM,再用3-氯过氧苯甲酸(mCPBA)将TMPM中的哌啶基氧化为2,2,6,6-四甲基哌啶氮氧自由基(TEMPO),得到负载链段为聚甲基丙烯酸甲酯的氮氧自由基嵌段共聚物PMMA-PTMA。通过红外光谱、核磁共振波谱、紫外可见分光光度计和凝胶渗透色谱等手段对共聚物进行表征。研究了嵌段共聚物在分子氧氧化体系下对伯醇的选择性催化氧化性能,并与均聚物PTMA和负载链段为聚乙二醇的氮氧自由基嵌段共聚物PEG-PTMA进行比较。结果表明,嵌段共聚物在分子氧氧化体系中催化性能良好,整体性能优于PTMA和PEG-PTMA,并且嵌段共聚物回收方便,可以实现重复使用。
The methyl methacrylate( MMA) and 2,2,6,6-tetramethylpiperidyl methacrylate( TMPM) monomers are sequentially polymerized to prepare block copolymer PMMA-PTMPM via the activators regenerated by electron transfer atom transfer radical polymerization( ARGET ATRP) method.The piperidinyl in TMPM is oxidized to 2,2,6,6-tetramethylpiperidine-1-oxyl( TEMPO) by 3-chloroperoxybenzoic acid( m CPBA),and a nitroxide radical block copolymer PMMA-PTMA with PMMA as support segment is obtained. The copolymer is characterized by infrared spectroscopy,nuclear magnetic resonance spectroscopy,ultraviolet-visible spectrophotometer and gel permeation chromatography.The properties of block copolymer in the selective catalytic oxidation of benzyl alcohol in the molecular oxygen oxidation system are studied,and compared with those of the homopolymeric PTMA and the nitroxide radical block copolymer PEG-PTMA with polyethylene glycol as support segment. The results show that the block copolymer exhibits excellent catalytic properties in the molecular oxygen oxidation system and has a better overall performance than PTMA and PEG-PTMA.Furthermore,the block copolymer can be easily recycled for reusing.
The methyl methacrylate( MMA) and 2,2,6,6-tetramethylpiperidyl methacrylate( TMPM) monomers are sequentially polymerized to prepare block copolymer PMMA-PTMPM via the activators regenerated by electron transfer atom transfer radical polymerization( ARGET ATRP) method.The piperidinyl in TMPM is oxidized to 2,2,6,6-tetramethylpiperidine-1-oxyl( TEMPO) by 3-chloroperoxybenzoic acid( m CPBA),and a nitroxide radical block copolymer PMMA-PTMA with PMMA as support segment is obtained. The copolymer is characterized by infrared spectroscopy,nuclear magnetic resonance spectroscopy,ultraviolet-visible spectrophotometer and gel permeation chromatography.The properties of block copolymer in the selective catalytic oxidation of benzyl alcohol in the molecular oxygen oxidation system are studied,and compared with those of the homopolymeric PTMA and the nitroxide radical block copolymer PEG-PTMA with polyethylene glycol as support segment. The results show that the block copolymer exhibits excellent catalytic properties in the molecular oxygen oxidation system and has a better overall performance than PTMA and PEG-PTMA.Furthermore,the block copolymer can be easily recycled for reusing.
引文
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[2]Liu S J,Hu Q Q,Zhao F Q,et al.Nitroxide polymer brushes prepared by surface-initiated ARGET ATRP and their selective oxidation performances[J].Express Polymer Letters,2014,8(11):862-868.
[3]Liu S J,Chu X M,Wang H L,et al.Preparation of nitroxide polymer brushes and their applications in the synthesis of an epoxidized soybean oil acrylate as an inhibitor[J].Industrial&Engineering Chemistry Research,2015,54:5475-5480.
[4]刘少杰,王华丽,崔笑菲,等.PEG基氮氧自由基嵌段共聚物的制备及其对伯醇的催化氧化性能[J].高校化学工程学报,2017,31(1):83-89.
[5]Senunelhack M F,Schmid C R,Cortes D A,et al.Oxidation of alcohols to aldehydes with oxygen and cupric ion,mediated by nitrosonium ion[J].Joumal of the Ameriean Chemieal Soeiety,1984,106(11):3374-3376.
[6]MarkóI E,Giles P R,Tsukazaki M,et al.Efficient,ecologically benign,aerobic oxidation of alcohols[J].J Org Chem,1999,64:2433-2439.
[7]Gamez P,Arends I W C E,Reedijka J,et al.Copper(Ⅱ)-catalysed aerobic oxidation of primary alcohols to aldehydes[J].Chem Commun,2003,(19):2414-2415.
[8]Gamez P,Arends I W C E,Sheldon R A,et al.Room temperature aerobic copper(Ⅱ)catalysed selective oxidation of primary alcohols to aldehydes[J].Full Papers,2004,346:805-811.
[9]刘柳,崔梦佳,张月成,等.Cu Br2/TEMPO/双齿希夫碱体系催化分子氧选择性氧化醇[J].河北工业大学学报,2014,43(5):42-48.
[10]苏玲,张月成,赵继全.树枝状聚酰胺胺负载TEMPO的合成及其催化分子氧氧化醇的性能[J].分子催化,2014,28(5):400-409.
[11]Zhang Y C,Guo Z M,Cao X H,et al.A Novel and simple catalyst system(Cu Br2)/TEMPO/Piperidine)for the oxidation of primary benzylic alcohols to aldehydes by oxygen[J].Journal of Molecular Catalysis(China),2014,28:317-328.