Download or read book Synthesis and Characterization of Lanthanide Phenolate Compounds and Their Catalytic Activity Towards Ring opening Polymerization of Cyclic Esters written by Pascal I. Binda and published by . This book was released on 2008 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Oxidation of New Divalent Lanthanide Bis phenolate Complexes and Their Applications in the Ring Opening Polymerization of Cyclic Esters written by Divine Timah Dugah and published by . This book was released on 2009 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lanthanides Chemistry and Use in Organic Synthesis written by Shu Kobayashi and published by Springer. This book was released on 2003-07-01 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions by numerous experts

Download or read book Olefin Metathesis and Polymerization Catalysts written by Yavuz Imamogammalu and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: Olefin metathesis reaction can be considered as one of the most successful organic reactions with many applications in the low molecular weight range and also in the polymer field. The use of catalysts with their selective and effective transformation properties in olefin metathesis I polymerization systems is a growing interest. There has been great effort and competition in developing active and commercially useful catalysts. The main aim of this ASI was to gather several research groups and also the people from industry. to present existing knowledge and latest results in the field. A wide range of topics through homogeneous and heterogeneous aspects have been considered. Attention has been drawn to the metal-carbene and metallacyclobutane complexes as active species, the initiation mechanisms, the stereochemistry and thermodynamics of these reactions. New catalytic systems for the metathesis of alkenes and alkynes and fot' ring opening polymeriZation I block copolymerization reactions have been introduced. Spectroscopic studies for the characteriZation of catalysts, simulation studies explaining the function of chain carrier species and polymer degradation have also been covered. A detailed industrial report concerning the patents and applications in olefin metathesis I cyc1001efin polymerization area, fabrication and derivation has been presented. This volume contains the main lectures and seminars given at the NATO Advanced Study Institute on " Olefin Metathesis and Polymerization Catalysts: Synthesis, Mechanism and Utilization", held at Akcay. Babkesir. Turkey between 10th and 22nd September 1989.

Download or read book Biometal Catalyzed Ring opening Polymerization of Cyclic Esters written by Osit Karroonnirun and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Biodegradable polyesters represent a class of extremely useful polymeric materials for many applications. Among these polyesters, the biodegradable and biocompatible, polylactide is very promising for many applications in both medical and industrial areas. Other biodegradable polymers such as polytrimethylene carbonate, polybutyrolactone, polyvalerolactone, and polycaprolactone can be blended or copolymerized with polylactide to fine tune the properties to fit the needs for their applications. The properties of these polymers and copolymers depend upon the tacticity of the polymers which can be directly controlled by the catalysts used for polymer production. Therefore, it has been of great interest to develop new selective catalytic systems for the ring-opening polymerization of lactide and other cyclic monomers. This dissertation focuses on developing new zinc and aluminum complexes and studying their selectivity and reactivity of these complexes for the ring-opening polymerization of lactide and other cyclic monomers, i.e. trimethylene carbonate, beta-butyrolactone, delta-valerolactone, and epsilon-caprolactone. Herein, aspects of the ring-opening polymerization of lactide and other cyclic monomers utilizing novel zinc and aluminum complexes will be discussed in detail. In the process for the ring-opening polymerization of lactide, chiral zinc half-salen complexes derived from natural amino acids have shown to be very active catalysts for producing polymers with high molecular weight and narrow polydispersities at ambient temperature. The chiral zinc complexes were found to catalyze rac-lactide to heterotactic polylactides with Pr values ranging from 0.68-0.89, depending on the catalyst and reaction temperature employed during the polymerization process. The reactivities of the various catalysts were greatly affected by substituents on the Schiff base ligands, with sterically bulky substituents being rate-enhancing. Furthermore, a series of both chiral and achiral aluminium half-salen complexes have been synthesized and characterized. These aluminum complexes all showed moderate selectivity to the ring-opening polymerization of rac-lactide to produce isotactic polylactide with Pm value up to 0.82 in toluene at 70 degrees C. Moreover, some of the studied aluminum complexes displayed epimerization of rac-lactide to meso-lactide during the polymerization process. Kinetic studies for the ring-opening polymerization of lactide utilizing these zinc and aluminum complexes are included in this dissertation. Along with these studies, the copolymerization of lactide with epsilon-caprolactone and delta-valerolactone will also be presented.

Download or read book Metallic Catalysts for Ring Opening Polymerization of Cyclic Esters and Related Compounds written by Isha Jain and published by Mohammed Abdul Sattar. This book was released on 2024-03-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers are extremely useful materials that have become an irreplaceable component of modern life. Synthetic polymers exhibit a multitude of applications in medicine, agriculture, packaging, and textile industries. Synthetic polymers like poly(ethylene) (PE), poly(propylene) (PP) and poly(styrene) (PS), poly (vinyl chloride) (PVC), poly (ethylene terephthalate) (PET), poly (urethane) (PU), etc. are obtained from petroleum-based sources and cover 90% of total synthesized plastics. A recent report revealed that global plastic production has increased from 270 million metric tons in the year 2010 to 370 million metric tons in 2020. The annual production volumes are expected to increase further in the coming years, approximately 590 million metric tons by the year 2050. Due to the non-biodegradability of synthetic polymers, each year post-consumer plastics generate huge waste which is diverted to landfills or the natural environment. These are pervasive and persistent in the environment and cause ecological and health risks at a global scale. In the recent past, a lot of scientific research efforts are devoted to replace non- biodegradable petroleum-based resources with renewable biodegradable polymers, and the polymer industry has witnessed remarkable progress. The bioplastics are rapidly gaining commercial interest globally, which is indicated by the up-trend in the market size which rose up to USD 13.11 billion in 2022 and expected to hit USD 46.1 billion by 2030. Estimated annual growth rate (CAGR) is expected to retain a value of 17.02% from 2022 to 2030. Among the various classes of biodegradable polymers, aliphatic polyesters are of leading interest since hydrolytic or enzymatic cleavage yields hydroxy carboxylic acids which can be metabolized to produce water and carbon dioxide as degradation products without formation of any toxic side product. For example, PLA (polylactide) is an attractive renewable alternative to the petro-based polymers, it decomposes in biological environments or in the presence of microorganisms to H20, C02 and humus to soil.

Download or read book Studies of the Ring opening Polymerization of Cyclic Ethers and Esters by Coordinate Catalysis written by Diana Navarro-Llobet and published by . This book was released on 2002 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanistic Insights Towards New Reactions and Materials written by Matthew Karl Kiesewetter and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysis is the enabling science of polymer synthesis, and new catalytic mechanisms yield new materials. The developement of organocatalysts for polymer synthesis has, particularly in the last decade, spawned an impressive array of new catalysts, processes and mechanistic insights. While the focus of most recent research in organocatalysis has concentrated on enantioselective synthesis of small molecules, organocatalysis offers a number of opportunities in polymer synthesis and was among the earliest methods of catalyzing the synthesis of polyesters. The enthalpy of ring opening of cyclic esters or carbonates drives the majority of organocatalyic polymerization reactions catalyzed by a still-evolving array of organocatalysts. Organocatalysts are thought to effect polymerization of cyclic esters by several mechanisms. Some proceed via a monomer activated mechanism whereby the catalyst activates the cyclic ester towards transesterification to the polymer chain. Others operate by an alcohol activation mechanism where the alcoholic end group of the growing polymer chain is activated to induce transesterification. Some are thought to be operative by a combination of these mechanisms. The unique reactivity offered by organocatalysts has provided access to precisely controlled macromolecular architectures and well-defined (co)polymers including a wide array of functionality. The notion that rate must be sacrificed to implement organocatalysts is fading with the discovery of transesterification organocatalysts that rival in reaction rate even the most active metal-containing catalysts. Cyclopentadienyl ruthenium complexes with quinaldic acid-type ligands are robust allylation catalysts in alcoholic solvents, but they are sensitive to dissolved oxygen, requiring reactions to be conducted in an inert atmosphere. Moving from alcoholic to neat aqueous solvents decreases the rate of deallylation but allows the reaction to be conducted in air without loss of catalyst activity over the course of the reaction. These complexes are also effective for the formation of allyl ethers, allowing the synthesis of poly(2,5-dihydrofuran) from the condensation polymerization of 2-cis-butene-1,4-diol. This material was previously deemed inaccessible via traditional polycondensation catalysts.

Download or read book Early Main Group Metal Catalysis written by Sjoerd Harder and published by John Wiley & Sons. This book was released on 2020-04-06 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Early Main Group Metal Catalysis gives a comprehensive overview of catalytic reactions in the presence of group 1 and group 2 metals. Chapters are ordered to reaction type, contain educational elements and deal with concepts illustrated by examples that cover the main developments. After a short introduction on polar organometallic chemistry and synthesis of early main group metal complexes, a variety of catalytic reactions are described, e.g. polymerization of alkenes, hydroamination and phosphination reactions, hydrosilylation, hydroboration and hydrogenation catalysis, as well as enantioselective and Lewis-acid catalysis. The book addresses organic chemists and researchers in industry interested in the state-of-the-art and new possibilities of early main group metal catalysis as well as newcomers to the field. Written by a team of leaders in the field, it is a very welcome addition to the area of main group metal chemistry, and to the field of catalysis.

Download or read book Novel Heterometallic Lanthanide III Tin II Tertiary butoxides for the Polymerization of Lactide written by Colin Douglas Canham and published by . This book was released on 2007 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Syntheses and Characterization of Lanthanide Complexes and Their Utility in Catalytic Epoxidation and Polymerization written by Samuel Aggrey Sakwa and published by . This book was released on 2006 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Synthesis and Characterization of Lanthanide copper Heterobimetallic Compounds written by Zhen Pang and published by . This book was released on 1993 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Lanthanide Complexes as Polymerisation Catalysts written by Hellen Elizabeth Dyer and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This Thesis describes the synthesis and characterisation of a series ofbisphenolate supported samarium borohydride, amide and zwitterionic rare earth complexes and their ability to effect the ring opening polymerisation (ROP) of cyclic esters and methylmethacrylate (MMA). Chapter 1 introduces ROP from both an industrial and an academic perspective and describes in detail the research in this area, with emphasis on rare earth initiators. The lanthanide elements and the bisphenolate ligand are also introduced. Chapter 2 describes the synthesis and characterisation ofbisphenolate supported samarium borohydride and silylamide complexes. Chapter 3 describes the ability of a selection of samarium borohydride and amide complexes to effect the ROP of the cyclic esters s-caprolactone (f-CL) and rac- lactide (rac-LA). Emphasis is placed on the effect that the nature of the bisphenolate pendant arm and the initiating moiety has on the polymerisation process. Chapter 4 describes the synthesis and characterisation of rare earth zwitterionic complexes and the ability ofa range of these complexes to effect the ROP of s-Cl. and rac-lactide. Mechanistic aspects ofthe ROP process will be discussed, as will the ability of these complexes to yield amide functionalised poly(rac-LA). Chapter 5 describes the ability ofbisphenolate samarium borohydride complexes to initiate the polymerisation of MMA. The experimental work conducted as part of this study is further supported computationally by calculations at the DFT level, both aspects will be described. Aspects concerning the synthesis and characterisation of the related borohydride derivative [Sm(N2siMe3NNPY)(BH4)2Li]oo will also be emphasised. Chapter 6 contains full experimental and characterising data for all 0 f the new compounds reported in this Thesis. Appendices A- T contain tables of selected crystallographic data for all new crystallographically characterised complexes described in this Thesis (partially on CD).

Download or read book The Synthesis and Ring opening Polymerisation of Novel Cyclic Esters from Malic Acid written by Ryan Jonathon Pounder and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chiral Indium Catalysts for the Ring opening Polymerization of Cyclic Esters written by Dinesh Chinthaka Aluthge and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Organocatalytic Ring opening Polymerization of Cyclic Lactones written by Pothupitiya Jinal U. and published by . This book was released on 2019 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Lanthanide Complexes with Phenalenide and Aromatic fused Cyclopentadienyls as Ligands written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis of yttrium phenalenide complexes 129-132 was achieved by salt metathesis reactions between ligand anions and YCI3. Ytterbium phenalenide complexes 133-137 were synthesized by protonolysis reactions between neutral ligands and Yb[N(SiMe3)2]2(THF)2. The solid state structure of (Pni1Bu)2Yb(THF) 136 reveals a unique n3 bonding pattern, however the electrons of the phenalenide ligand remain delocalized even when bonded to the metal center. Mono-alkyl complexes (PCpR)2Y(CH2SiMe3)(THFSiMe3)(THF) 147-149 (R = Me. Ph. H) and bis-alkyl complexes (PCp*)Y(CH2SiMe3)2(THF) 150 and (sCp)Y(CH2SiMe3)2(THF) 152 were synthesized by direct protonolysis reactions between Y(CH2SiMe3)3(THF)2 and neutral ligands. When treated with phenylsilane, complex 148 generated the crowded hydride dimer [(PCpPh)2Y(u-H)]2 161. Complexes 150 and 152 undergo acid-base. metallation. insertion reactions and polymerization of small substrates. A variable temperature `H NMR study of 150 and 152 at low temperature reveals an equilibrium between 150/152-THF and 1501152. The THF-free complexes. 150/152-THF. appear to undergo inversion of a pyramidal ground state structure to generate a C2 symmetric intermediate. The X-ray structures of 136, 147, 150. 152, (sCp)Y(CH2SiMe3)2(bipy) 154, 161. [PCp*Y(CCSiMe3)(THF)]2(u2-CCSiMe3)2] 167, acetylide cluster 169 and bis-(Me3Si)2Cp yttrium chloride dimer 176 were determined and structural features discussed.