共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Mechelle R. Bennett Dr. Pratik Gurnani Prof. Phil J. Hill Prof. Cameron Alexander Prof. Frankie J. Rawson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(12):4780-4785
The ability to harness cellular redox processes for abiotic synthesis might allow the preparation of engineered hybrid living systems. Towards this goal we describe a new bacteria-mediated iron-catalysed reversible deactivation radical polymerisation (RDRP), with a range of metal-chelating agents and monomers that can be used under ambient conditions with a bacterial redox initiation step to generate polymers. Cupriavidus metallidurans, Escherichia coli, and Clostridium sporogenes species were chosen for their redox enzyme systems and evaluated for their ability to induce polymer formation. Parameters including cell and catalyst concentration, initiator species, and monomer type were investigated. Water-soluble synthetic polymers were produced in the presence of the bacteria with full preservation of cell viability. This method provides a means by which bacterial redox systems can be exploited to generate “unnatural” polymers in the presence of “host” cells, thus setting up the possibility of making natural–synthetic hybrid structures and conjugates. 相似文献
3.
Weijia Fan Dr. Yasuyuki Nakamura Prof. Shigeru Yamago 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):17006-17010
Functionalized or multivalent organotellurium chain‐transfer agents (CTAs) for living radical polymerization were synthesized by post‐modification, which involved the condensation between a carboxylic‐acid‐functionalized CTA and various amines in excellent yields without affecting the reactive tellurium moiety. The CTAs exhibited high synthetic versatility for radical polymerization and gave structurally well‐controlled polymers, such as multiarmed polymers, from various monomers. Because all new CTAs are easily available on a large scale by simple purification, the current method significantly facilitates macromolecular engineering based on organotellurium‐mediated radical polymerization (TERP). 相似文献
4.
Vladimir I. Lozinsky Roman V. Ivanov Elena V. Kalinina Galina I. Timofeeva Alexei R. Khokhlov 《Macromolecular rapid communications》2001,22(17):1441-1446
The radical polymerisation of acrylamide initiated with a persulfate/tertiary amine redox pair was performed in liquid (+5 to +35°C) and moderately frozen (–10 to –30°C) aqueous solutions. The reaction in frozen systems resulted in the pronounced increase in the molecular weight of the polymer. The temperature dependence of the yield and molecular weight of cryogenically produced polyacrylamide were of extreme character with a maximum for both parameters in the vicinity of –12.5°C. 相似文献
5.
Tor Kit Goh Satoshi Yamashita Kotaro Satoh Anton Blencowe Masami Kamigaito Greg G. Qiao 《Macromolecular rapid communications》2011,32(5):456-461
The efficient formation of low polydispersity core cross‐linked star (CCS) polymers via controlled/living radical polymerization (LRP) and the arm‐first approach was found to be dependant on the mediating catalyst system. The Ru catalyst, Ru(Ind)Cl(PPh3)2 Cat. 1 , and tertiary amine co‐catalyst were used to synthesize highly living poly(methyl methacrylate) (PMMA) macroinitiators, which were then linked together with ethylene glycol dimethacrylate (EGDMA) to form PMMAarmPEGDMAcore CCS polymers. The quantitative and near‐quantitative synthesis of CCS polymers were observed for low to moderate molecular weight macroinitiators ( = 8 and 20 kDa), respectively. Lower conversions were observed for high‐molecular weight macroinitiators ( ≥ 60 kDa). Overall, an improvement of between 10 and 20% was observed when comparing the Cat. 1 system to a conventional Cu‐catalyzed system. This significant improvement in macroinitiator‐to‐star conversion is explained in the context of catalyst system selection and CCS polymer formation.
6.
Lifen Zhang Jie Miao Zhenping Cheng Xiulin Zhu 《Macromolecular rapid communications》2010,31(3):275-280
Initiators for continuous activator regeneration in atom transfer radical polymerization (ICAR ATRP) is a new technique for conducting ATRP. ICAR ATRP has many strong advantages over normal ATRP, such as forming the reductive transition metal species in situ using oxidatively stable transition metal species and a lower amount of metal catalyst in comparison with the normal ATRP system. In this work, the iron‐mediated ICAR ATRP of styrene and methyl methacrylate are reported for the first time using oxidatively stable FeCl3 · 6H2O as the catalyst in the absence of any thermal radical initiator. The kinetics of the polymerizations and effect of different polymerization conditions are studied. It is found that the polymerization of styrene can be conducted well even if the amount of iron(III ) is as low as 50 ppm.
7.
8.
9.
Hongjuan Jiang Lifen Zhang Jinlong Pan Xiaowu Jiang Zhenping Cheng Xiulin Zhu 《Journal of polymer science. Part A, Polymer chemistry》2012,50(11):2244-2253
Methyl methacrylate (MMA) were successfully polymerized by atom transfer radical polymerization with activator generated by electron transfer (AGET ATRP) using copper or iron wire as the reducing agent at 90°C. Well‐controlled polymerizations were demonstrated using an oxidatively stable iron(III) chloride hexahydrate (FeCl3·6H2O) as the catalyst, ethyl 2‐bromoisobutyrate (EBiB) as the initiator, and tetrabutylammonium bromide (TBABr) or triphenylphosphine as the ligand. The polymerization rate was fast and affected by the amount of catalyst and type of reducing agents. For example, the polymerization rate of bulk AGET ATRP with a molar ratio of [MMA]0/[EBiB]0/[FeCl3·6H2O]0/[TBABr]0 = 500/1/0.5/1 using iron wire (the conversion reaches up to 82.2% after 80 min) as the reducing agent was faster than that using copper wire (the conversion reaches up to 86.1% after 3 h). At the same time, the experimental Mn values of the obtained poly(methyl methacrylate) were consistent with the corresponding theoretical ones, and the Mw/Mn values were narrow (~1.3), showing the typical features of “living”/controlled radical polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
10.
Iron‐Induced Regio‐ and Stereoselective Addition of Sulfenyl Chlorides to Alkynes by a Radical Pathway 下载免费PDF全文
Dr. Masayuki Iwasaki Tomoya Fujii Prof. Dr. Kiyohiko Nakajima Prof. Dr. Yasushi Nishihara 《Angewandte Chemie (International ed. in English)》2014,53(50):13880-13884
The radical addition of the Cl? S σ‐bond in sulfenyl chlorides to various C? C triple bonds has been achieved with excellent regio‐ and stereoselectivity in the presence of a catalytic amount of a common iron salt. The reaction is compatible with a variety of functional groups and can be scaled up to the gram‐scale with no loss in yield. As well as terminal alkynes, internal alkynes underwent stereodefined chlorothiolation to provide tetrasubstituted alkynes. Preliminary mechanistic investigations revealed a plausible radical process involving a sulfur‐centered radical intermediate via iron‐mediated homolysis of the Cl? S bond. The resulting chlorothiolation adducts can be readily transformed to the structurally complex alkenyl sulfides by cross‐coupling reactions. The present reaction can also be applied to the complementary synthesis of the potentially useful bis‐sulfoxide ligands for transition‐metal‐catalyzed reactions. 相似文献
11.
Dr. Anna Hedström Dr. Zakieh Izakian Irma Vreto Dr. Carl‐Johan Wallentin Prof. Dr. Per‐Ola Norrby 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5946-5953
The radical nature of iron‐catalyzed cross‐coupling between Grignard reagents and alkyl halides has been studied by using a combination of competitive kinetic experiments and DFT calculations. In contrast to the corresponding coupling with aryl halides, which commences through a classical two‐electron oxidative addition/reductive elimination sequence, the presented data suggest that alkyl halides react through an atom‐transfer‐initiated radical pathway. Furthermore, a general iodine‐based quenching methodology was developed to enable the determination of highly accurate concentrations of Grignard reagents, a capability that facilitates and increases the information output of kinetic investigations based on these substrates. 相似文献
12.
Jian‐Zhuang Chen Kun Cui Shu‐Yuan Zhang Peng Xie Qiao‐Ling Zhao Jin Huang Li‐Ping Shi Guang‐Yu Li Zhi Ma 《Macromolecular rapid communications》2009,30(7):532-538
Well‐defined polymethylene‐block‐polystyrene (PM‐b‐PS) diblock copolymers were synthesized via a combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) of styrene. A series of hydroxyl‐terminated polymethylenes (PM‐OHs) with different molecular weight and narrow molecular weight distribution were prepared using living polymerization of ylides following efficient oxidation in a quantitive functionality. Then, the macroinitiators (PM‐MIs ( = 1 900–15 000; PDI = 1.12–1.23)) transformed from PM‐OHs in ≈ 100% conversion initiated ATRPs of styrene to construct PM‐b‐PS copolymers. The GPC traces indicated the successful extension of PS segment ( of PM‐b‐PS = 5 000–41 800; PDI = 1.08–1.23). Such copolymers were characterized by 1H NMR and DSC.
13.
Iron‐catalyzed hydrosilylation is one of the most popular reduction reactions owing to the high natural abundance, low cost and low toxicity of iron and silicon. This paper introduces an advance in iron‐catalyzed hydrosilylation of olefins, aldehydes, ketones and amides. Some reactions exhibit good functional group tolerance and chemoselectivities. These protocols provide economical, sustainable and practical tools for organic chemists. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
14.
Glen R. Jones Dr. Athina Anastasaki Richard Whitfield Nikolaos Engelis Evelina Liarou Prof. David M. Haddleton 《Angewandte Chemie (International ed. in English)》2018,57(33):10468-10482
Key advances within the past 10 years have transformed copper‐mediated radical polymerization from a technique which was not very tolerant of protic media into a range of closely related processes capable of controlling the polymerization of a wide range of monomers in pure water at ppm catalyst loadings. This approach has afforded water‐soluble macromolecules of desired molecular weight, architecture, and chemical functionality, with applications ranging from drug delivery to oil processing. In this Review we highlight and critically evaluate the synthetic methods that have been developed to control radical polymerization in water by using copper complexes as well as identify future areas of interest and challenges still to be overcome. 相似文献
15.
Four nitroso esters were prepared by oxidation of 4,4‐dimethyl dihydro‐1,3‐oxazine or 4,4‐dimethyl‐2‐oxazoline with two equiv of m‐chloroperoxybenzoic acid. All of them can be applied in radical addition‐coupling polymerization to produce periodic polymer together with introduction of ester group at side chain. Compared with 2‐methyl‐2‐nitrosopropane, 2‐nitroso‐2‐methyl‐4‐acetoxypentane and 2‐methyl‐2‐nitrosopropyl hexanoate present good stability at high temperature up to 70 °C and can result polymer with high molecular weight. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 810–815 相似文献
16.
17.
The synthesis and electrochemical performance of three‐dimensionally ordered macroporous (3DOM) nitroxide polymer brush electrodes for organic radical batteries are reported. The 3DOM electrodes are synthesized via polystyrene colloidal crystal templating with electropolymerization of polypyrrole, modification of surface initiator, and surface‐initiated atom transfer radical polymerization. The discharge capacity of the 3DOM electrodes is proportional to the thickness of the inverse opal. The discharge capacity of the 3DOM electrode at a discharge rate of 5 C is 40 times higher than that of the planar electrode; its cycle‐life performance exhibits 96.1% retention after 250 cycles. 相似文献
18.
Athina Anastasaki Alice J. Haddleton Qiang Zhang Alexandre Simula Martijn Droesbeke Paul Wilson David M. Haddleton 《Macromolecular rapid communications》2014,35(10):965-970
The polymerisation of N‐acryloylmorpholine in water is reported utilising Cu(0)‐mediated living radical polymerisation (SET‐LRP). The inherent instability of [CuI(Me6‐Tren)Br] in aqueous solution is exploited via rapid disproportionation to prepare Cu(0) particles and [CuII(Me6‐Tren)Br2] in situ prior to addition of monomer and initiator. Quantitative conversion is attained within 30 min for various degrees of polymerisation (DPn = 20–640) with SEC showing symmetrical narrow molecular weight distributions (Đ < 1.18) in all cases. Optimised conditions are subsequently applied for the preparation of a diblock copolymer poly(NIPAm)‐b‐(N‐acryloylmorpholine), illustrating the versatility of this approach.
19.
Satu Strandman Petri Pulkkinen Heikki Tenhu 《Journal of polymer science. Part A, Polymer chemistry》2005,43(15):3349-3358
The effect of the steric hindrance on the initiating properties of two multifunctional resorcinarene‐based initiators in atom transfer radical polymerization (ATRP) was studied by using Cu(I)‐complexes of three multidentate amine ligands in the polymerization of tert‐butyl acrylate and methyl methacrylate. These ligands are less sterically hindered and have higher activities in the catalysis of ATRP of (meth)acrylates than 2,2′‐bipyridine. The polymerizations were faster and more controlled than with the 2,2′‐bipyridyl catalyst, but the tendency for bimolecular coupling increased. Even though the initiator was octafunctional, the resulting star polymers had only four arms. This indicates that the steric hindrance arising from the conformations of the initiators determines the structure of the polymer, but the ligand noticeably affects the controllability of the polymerization © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3349–3358, 2005 相似文献