Download or read book Photochemical Synthesis and Electrocyclic Ring Opening of Cyclobutene fused Bicyclic Systems written by Michael J. Robertson-Ralph and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Photochemical and Mechanochemical Ring Opening of Cyclobutene from First Principles written by Mitchell T. Ong and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A textbook example of a pericyclic reaction is the electrocyclic ring opening of cyclobutene. The stereochemical outcome of this reaction can typically be predicted using the Woodward-Hoffmann rules, which are based on conservation of orbital symmetry. According to these rules, the thermal ring opening reaction will proceed in conrotatory fashion, while the photochemical ring opening reaction will proceed in disrotatory fashion. Over the years, there have been very few exceptions to the Woodward-Hoffmann rules. However, two apparent exceptions to these rules occur when the ring opening of cyclobutene is initiated by exciting the molecule with light or by applying a mechanical force. In this work, we use first principles quantum mechanics and molecular dynamics to examine the photochemical and mechanochemical ring opening of cyclobutene. We use the ab initio multiple spawning (AIMS) method in order to examine the short time dynamics of cyclobutene. We have integrated the COLUMBUS software package into AIMS, which contains analytical gradients and nonadiabatic couplings for multi-reference configuration interaction (MRCI). This provides us with a more accurate potential energy surface in which to run our dynamics on. We find that the stereochemistry for ring opening is determined on the ground state. We have also identified two S1/S0 intersections that could be relevant to the photochemical ring opening reaction. One of these intersections contains a sizable C=C torsional angle, which could explain the mixture of conrotatory and disrotatory products seen in experiment. In addition, we model the mechanical response of cyclobutene within the context of a force-modified potential energy surface (FMPES). Using this model, we perform ab initio steered molecular dynamics (AISMD) to predict possible reaction outcomes when an external force is applied. Furthermore, we locate minimum energy pathways directly on the FMPES using the nudged elastic band (NEB) algorithm. Application of an external force can bias the reaction to produce a specific product by reshaping the potential energy surface and effectively blocking off access to other competing pathways. Barrier heights and stationary point geometries along the pathways can also change as a function of the force. Finally, we apply AISMD and NEB to other new mechanophores that are currently being studied including gem-difluorocyclopropane and dicyano-cyclobutane. Both of these methods can be used to screen new mechanophores, which will aid in designing new polymeric materials that respond favorably to mechanical stress.
Download or read book The Photochemistry of Some Fused Ring Cyclobutenes and of Trienes Substituted with an Allylic Hydroxyl Group written by Jeanne Elizabeth Haubrich and published by . This book was released on 1987 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book DFT Studies of the Electrocyclic Ring Opening of Cyclobutene written by Nicholas Georges and published by . This book was released on 2008 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pericyclic Reactions in Organic Synthesis written by Julia Mae Robinson-Surry and published by . This book was released on 2011 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part I of this thesis describes a formal, metal-free, [2 + 2 + 2] cycloaddition strategy based on a cascade of two pericyclic processes. An intramolecular propargylic ene reaction of a 1,6-diyne is used to generate a vinylallene, which then reacts in an inter- or intramolecular Diels-Alder reaction with an alkenyl or alkynyl dienophile. Reactions involving unsymmetrical alkenyl and alkynyl dienophiles proceed with good to excellent regioselectivity, and endo products are formed exclusively. The mechanism of several earlier fully intramolecular related transformations have been shown to involve an analogous process rather than the diradicalmediated pathways proposed previously. Part II of this thesis describes a [4 + 4] annulation strategy involving the intramolecular [4 + 2] cycloaddition of conjugated enynes with activated cyclobutene derivatives to access intermediates containing bicyclo[4.2.0]-2,4-octadiene moieties that then undergo electrocyclic ring opening reactions to provide 1,3,5-cyclooctatrienes. Five novel cyclooctatrienes have been prepared using this method. Part III of this thesis describes the use of supercritical carbon dioxide as an environmentally friendly alternative to conventional solvents for the synthesis of a variety of carboxylic amides. The addition of amines to ketenes generated in situ via the retro-ene reaction of alkynyl ethers provides amides in good yield, in many cases with ethylene as the only byproduct of the reaction. With the exception of primary, unbranched amines, potential side reactions involving addition of the amines to carbon dioxide are not competitive with the desired C-N bond-forming reaction. The amide synthesis is applicable to the preparation of p-hydroxy and P-amino amide derivatives, as well as amides bearing isolated carbon-carbon double bonds.
Download or read book Applied Science Technology Index written by and published by . This book was released on 1981 with total page 2812 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Conservation of Orbital Symmetry written by R. B. Woodward and published by Elsevier. This book was released on 2013-10-22 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Conservation of Orbital Symmetry examines the principle of conservation of orbital symmetry and its use. The central content of the principle was that reactions occur readily when there is congruence between orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence does not obtain—or to put it more succinctly, orbital symmetry is conserved in concerted reaction. This principle is expected to endure, whatever the language in which it may be couched, or whatever greater precision may be developed in its application and extension. The book opens with a review of the elementary aspects of the molecular orbital theory of bonding. This is followed by separate chapters on correlation diagrams, the conservation of orbital symmetry, theory of electrocyclic reactions, theory of cycloadditions and cycloreversions, and theory of sigmatropic reactions. Subsequent chapters deal with group transfers and eliminations; secondary conformational effects in concerted cycloaddition reactions; and generalized selection rules for pericyclic reactions.
Download or read book Modern Applications of Cycloaddition Chemistry written by Paolo Quadrelli and published by Elsevier. This book was released on 2019-03-20 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern Applications of Cycloaddition Chemistry examines this area of organic chemistry, with special attention paid to cycloadditions in synthetic and mechanistic applications in modern organic chemistry. While many books dedicated to cycloaddition reactions deal with the synthesis of heterocycles, general applications, specific applications in natural product synthesis, and the use of a class of organic compounds, this work sheds new light on pericyclic reactions by demonstrating how these valuable tools elegantly solve synthetic and mechanistic problems. The work examines how pericyclic reactions have been extensively applied to different chemistry areas, such as chemical biology, biological processes, catalyzed cycloaddition reactions, and more. This work will be useful for organic chemists who deal with organic chemistry, medicinal chemistry, agrochemistry and material chemistry. Provides details on the synthesis of antiviral and anticancer compounds, marking the key role of unconventional catalyzed cycloaddition reactions for preparing new derivatives in a unique reaction pathway that is scalable in industrial processes Contains the most up-to-date review of the use of pericyclic reactions in drug delivery Includes the enzyme-catalyzed processes involving cycloaddition reactions for different targets, demonstrating that cycloaddition is more common in nature than expected Features new applications for cycloadditions in material chemistry and provides a general view of the most recent results in the area
Download or read book Artificial Metalloenzymes and MetalloDNAzymes in Catalysis written by Montserrat Diéguez and published by John Wiley & Sons. This book was released on 2018-02-21 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important reference for researchers in the field of metal-enzyme hybrid catalysis Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a comprehensive review of the most current strategies, developed over recent decades, for the design, synthesis, and optimization of these hybrid catalysts as well as material about their application. The contributors—noted experts in the field—present information on the preparation, characterization, and optimization of artificial metalloenzymes in a timely and authoritative manner. The authors present a thorough examination of this interesting new platform for catalysis that combines the excellent selective recognition/binding properties of enzymes with transition metal catalysts. The text includes information on the various applications of metal-enzyme hybrid catalysts for novel reactions, offers insights into the latest advances in the field, and contains an informative perspective on the future: Explores the development of artificial metalloenzymes, the modern and strongly evolving research field on the verge of industrial application Contains a comprehensive reference to the research area of metal-enzyme hybrid catalysis that has experienced tremendous growth in recent years Includes contributions from leading researchers in the field Shows how this new catalysis combines the selective recognition/binding properties of enzymes with transition metal catalysts Written for catalytic chemists, bioinorganic chemists, biochemists, and organic chemists, Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a unique reference to the fundamentals, concepts, applications, and the most recent developments for more efficient and sustainable synthesis.
Download or read book Essentials of Pericyclic and Photochemical Reactions written by Biswanath Dinda and published by Springer. This book was released on 2016-11-18 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a concise introduction to pericyclic and photochemical reactions for organic synthesis. In the first part about pericyclic reactions, the author explains electrocyclic reactions, cycloaddition reactions, sigmatropic rearrangements, and group transfer reactions. The second part on photochemistry is dedicated to photochemical reactions of a variety of compound classes, including alkenes, dienes, and polyenes, carbonyl compounds, and aromatic compounds. Additionally, photofragmentation reactions are described in a dedicated chapter. The last chapter gives an outlook on applications of photochemistry and natural photochemical phenomena. Both parts start with a comprehensive presentation of the general principles of the pericyclic and photochemical reactions. All chapters are rich in examples, which help illustrate the explained principles and establish ties to results and trends in recent research. Additionally, each chapter offers exercises for students, and solutions to the problems are provided in a separate appendix. This book nicely illustrates the utility of pericyclic and photochemical reactions and provides students and researchers with the tools to apply them routinely for an efficient synthesis of complex organic molecules. It will therefore appeal to advanced undergraduate students, graduate and postgraduate students, and even to practitioners and scientists in the field of organic synthesis. The rich examples and exercises will also make it a versatile tool for teachers and lecturers.
Download or read book The Art of Writing Reasonable Organic Reaction Mechanisms written by Robert B. Grossman and published by Springer Science & Business Media. This book was released on 2007-07-31 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intended for students of intermediate organic chemistry, this text shows how to write a reasonable mechanism for an organic chemical transformation. The discussion is organized by types of mechanisms and the conditions under which the reaction is executed, rather than by the overall reaction as is the case in most textbooks. Each chapter discusses common mechanistic pathways and suggests practical tips for drawing them. Worked problems are included in the discussion of each mechanism, and "common error alerts" are scattered throughout the text to warn readers about pitfalls and misconceptions that bedevil students. Each chapter is capped by a large problem set.
Download or read book The Patern B chi Reaction written by Maurizio D’Auria and published by Cambridge Scholars Publishing. This book was released on 2019-07-29 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book represents the most complete description of the scientific results obtained on a photochemical experiment described 110 years ago by the Italian scientist Emanuele Paternò. This detailed that the photochemical reaction between a carbonyl compound and an alkene gives a corresponding oxetane. This oxetane ring is present in several naturally occurring compounds and bioactive compounds, and can be obtained with high regio- and stereoselectivity.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2000 with total page 846 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Orbital Interaction Theory of Organic Chemistry written by Arvi Rauk and published by John Wiley & Sons. This book was released on 2004-04-07 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: A practical introduction to orbital interaction theory and its applications in modern organic chemistry Orbital interaction theory is a conceptual construct that lies at the very heart of modern organic chemistry. Comprising a comprehensive set of principles for explaining chemical reactivity, orbital interaction theory originates in a rigorous theory of electronic structure that also provides the basis for the powerful computational models and techniques with which chemists seek to describe and exploit the structures and thermodynamic and kinetic stabilities of molecules. Orbital Interaction Theory of Organic Chemistry, Second Edition introduces students to the fascinating world of organic chemistry at the mechanistic level with a thoroughly self-contained, well-integrated exposition of orbital interaction theory and its applications in modern organic chemistry. Professor Rauk reviews the concepts of symmetry and orbital theory, and explains reactivity in common functional groups and reactive intermediates in terms of orbital interaction theory. Aided by numerous examples and worked problems, he guides readers through basic chemistry concepts, such as acid and base strength, nucleophilicity, electrophilicity, and thermal stability (in terms of orbital interactions), and describes various computational models for describing those interactions. Updated and expanded, this latest edition of Orbital Interaction Theory of Organic Chemistry includes a completely new chapter on organometallics, increased coverage of density functional theory, many new application examples, and worked problems. The text is complemented by an interactive computer program that displays orbitals graphically and is available through a link to a Web site. Orbital Interaction Theory of Organic Chemistry, Second Edition is an excellent text for advanced-level undergraduate and graduate students in organic chemistry. It is also a valuable working resource for professional chemists seeking guidance on interpreting the quantitative data produced by modern computational chemists.
Download or read book Frontier Orbitals and Organic Chemical Reactions written by Ian Fleming and published by John Wiley & Sons. This book was released on 1976-01-01 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a basic introduction to frontier orbital theory with a review of its applications in organic chemistry. Assuming the reader is familiar with the concept of molecular orbital as a linear combination of atomic orbitals the book is presented in a simple style, without mathematics making it accessible to readers of all levels.
Download or read book Handbook of Synthetic Photochemistry written by Angelo Albini and published by John Wiley & Sons. This book was released on 2010-02-01 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unique in its focus on preparative impact rather than mechanistic details, this handbook provides an overview of photochemical reactions classed according to the structural feature that is built in the photochemical step, so as to facilitate use by synthetic chemists unfamiliar with this topic. An introductory section covers practical questions on how to run a photochemical reaction, while all classes of the most important photocatalytic reactions are also included. Perfect for organic synthetic chemists in academia and industry.
Download or read book Strategic Applications of Named Reactions in Organic Synthesis written by Laszlo Kurti and published by Elsevier. This book was released on 2005-04-29 with total page 808 pages. Available in PDF, EPUB and Kindle. Book excerpt: Kurti and Czako have produced an indispensable tool for specialists and non-specialists in organic chemistry. This innovative reference work includes 250 organic reactions and their strategic use in the synthesis of complex natural and unnatural products. Reactions are thoroughly discussed in a convenient, two-page layout--using full color. Its comprehensive coverage, superb organization, quality of presentation, and wealth of references, make this a necessity for every organic chemist. * The first reference work on named reactions to present colored schemes for easier understanding* 250 frequently used named reactions are presented in a convenient two-page layout with numerous examples* An opening list of abbreviations includes both structures and chemical names * Contains more than 10,000 references grouped by seminal papers, reviews, modifications, and theoretical works * Appendices list reactions in order of discovery, group by contemporary usage, and provide additional study tools* Extensive index quickly locates information using words found in text and drawings
