Author: G. M. Badger
Publisher: Cambridge University Press
ISBN: 9780521073394
Category : Science
Languages : en
Pages : 141
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Book Description
Originally published in 1969, this book analyses the special properties of benzene and its derivatives, which give them their distinct aromatic character. The text first discusses the structure of benzene, including the light shed on it by physical methods and wave mechanics, and the structure of polycyclic benzenoid hydrocarbons and heterocyclic aromatic compounds. Aromaticity is defined as a function of the electronic structure of the molecule or ion in question and it is shown that this has important consequences in respect of bond lengths, resonance energies, electronic absorption spectra and induced ring currents. Final chapters discuss how far aromatic character and aromaticity are associated with non-benzenoid hydrocarbons and with more complex systems.
Author: Israel Fernandez
Publisher: Elsevier
ISBN: 0128227435
Category : Science
Languages : en
Pages : 517
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Book Description
Evaluating the aromaticity of a molecular system and the influence of this concept on its properties is a crucial step in the development of novel aromatic systems. Modern computational methods can provide researchers with a high level of insight into such aromaticity, but identifying the most appropriate method for assessing a specific system can prove difficult. Aromaticity: Modern Computational Methods and Applications reviews the latest state-of-the-art computational methods in this field and discusses their applicability for evaluating the aromaticity of a system. In addition to covering aromaticity for typical organic molecules, this volume also explores systems possessing transition metals in their structures, macrocycles and even transition structures. The influence of the aromaticity on the properties of these species (including the structure, magnetic properties and reactivity) is highlighted, along with potential applications in fields including materials science and medicinal chemistry. Finally, the controversial and fuzzy nature of aromaticity as a concept is discussed, providing the basis for an updated and more comprehensive definition of this concept. Drawing on the knowledge of an international team of experts, Aromaticity: Modern Computational Methods and Applications is a unique guide for anyone researching, studying or applying principles of aromaticity in their work, from computational and organic chemists to pharmaceutical and materials scientists. - Reviews a range of computational methods to assess the aromatic nature of different compounds, helping readers select the most useful tool for the system they are studying - Presents a complete guide to the key concepts and fundamental principles of aromaticity - Provides guidance on identifying which variables should be modified to tune the properties of an aromatic system for different potential applications
Author: Tadeusz Marek Krygowski
Publisher: Springer Science & Business Media
ISBN: 3540683291
Category : Science
Languages : en
Pages : 355
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Book Description
Heterocyclic chemistry is the biggest branch of chemistry covering two-thirds of the chemical literature. Aromaticity in Heterocyclic Compounds covers hot topics of frontier research summarized by reputed scientists in the field.
Author: Mandeep Dalal
Publisher: Dalal Institute
ISBN: 8195242731
Category : Science
Languages : en
Pages : 450
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Book Description
An advanced-level textbook of organic chemistry for the graduate (B.Sc) and postgraduate (M.Sc) students of Indian and foreign universities. This book is a part of the four-volume series, entitled “A Textbook of Organic Chemistry – Volume I, II, III, IV”. CONTENTS: Chapter 1. Nature of Bonding in Organic molecules: Delocalized chemical bonding; Conjugation; Cross conjugation; Resonance; Hyperconjugation; Tautomerism; Aromaticity in benzenoid and nonbenzenoid compounds; Alternant and non-alternant hydrocarbons; Huckel’s rule: Energy level of p-molecular orbitals; Annulenes; Antiaromaticity; Homo-aromaticity; PMO approach; Bonds weaker than covalent; Addition compounds: crown ether complexes and cryptands, inclusion compounds, cyclodextrins; Catenanes and rotaxanes. Chapter 2. Stereochemistry: Chirality; Elements of symmetry; Molecules with more than one chiral centre: diastereomerism; Determination of relative and absolute configuration (octant rule excluded) with special reference to lactic acid, alanine & mandelic acid; Methods of resolution; Optical purity; Prochirality; Enantiotopic and diastereotopic atoms, groups and faces; Asymmetric synthesis: Cram’s Rule and its modifications, Prelog’s rule; Conformational analysis of cycloalkanes (upto six membered rings); Decalins; Conformations of sugars; Optical activity in absence of chiral carbon (biphenyls, allenes and spiranes); Chirality due to helical shape; Geometrical isomerism in alkenes and oximes; Methods of determining the configuration. Chapter 3. Reaction Mechanism: Structure and Reactivity: Types of mechanisms; Types of reactions; Thermodynamic and kinetic requirements; Kinetic and thermodynamic control; Hammond’s postulate; Curtin-Hammett principle; Potential energy diagrams: Transition states and intermediates; Methods of determining mechanisms; Isotope effects; Hard and soft acids and bases; Generation, structure, stability and reactivity of carbocations, carbanions, free radicals, carbenes and nitrenes; Effect of structure on reactivity; The Hammett equation and linear free energy relationship; Substituent and reaction constants; Taft equation. Chapter 4. Carbohydrates: Types of naturally occurring sugars; Deoxy sugars; Amino sugars; Branch chain sugars; General methods of determination of structure and ring size of sugars with particular reference to maltose, lactose, sucrose, starch and cellulose. Chapter 5. Natural and Synthetic Dyes: Various classes of synthetic dyes including heterocyclic dyes; Interaction between dyes and fibers; Structure elucidation of indigo and Alizarin. Chapter 6. Aliphatic Nucleophilic Substitution: The SN2, SN1, mixed SN1 and SN2, SNi , SN1’, SN2’, SNi’ and SET mechanisms; The neighbouring group mechanisms; Neighbouring group participation by p and s bonds; Anchimeric assistance; Classical and nonclassical carbocations; Phenonium ions; Common carbocation rearrangements; Applications of NMR spectroscopy in the detection of carbocations; Reactivity- effects of substrate structure, attacking nucleophile, leaving group and reaction medium; Ambident nucleophiles and regioselectivity; Phase transfer catalysis. Chapter 7. Aliphatic Electrophilic Substitution: Bimolecular mechanisms – SE2 and SEi; The SE1 mechanism; Electrophilic substitution accompained by double bond shifts; Effect of substrates, leaving group and the solvent polarity on the reactivity. Chapter 8. Aromatic Electrophilic Substitution: The arenium ion mechanism; Orientation and reactivity; Energy profile diagrams; The ortho/para ratio; ipso attack; Orientation in other ring systems; Quantitative treatment of reactivity in substrates and electrophiles; Diazonium coupling; Vilsmeir reaction; Gattermann-Koch reaction. Chapter 9. Aromatic Nucleophilic Substitution: The ArSN1, ArSN2, benzyne and SRN1 mechanisms; Reactivity – effect of substrate structure, leaving group and attacking nucleophile; The von Richter, Sommelet-Hauser, and Smiles rearrangements. Chapter 10. Elimination Reactions: The E2, E1 and E1cB mechanisms; Orientation of the double bond; Reactivity – effects of substrate structures, attacking base, the leaving group and the medium; Mechanism and orientation in pyrolytic elimination. Chapter 11. Addition to Carbon-Carbon Multiple Bonds: Mechanistic and stereochemical aspects of addition reactions involving electrophiles, nucleophiles and free radicals; Regio–and chemoselectivity: orientation and reactivity; Addition to cyclopropane ring; Hydrogenation of double and triple bonds; Hydrogenation of aromatic rings; Hydroboration; Michael reaction; Sharpless asymmetric epoxidation. Chapter 12. Addition to Carbon-Hetero Multiple Bonds: Mechanism of metal hydride reduction of saturated and unsaturated carbonyl compounds, acids, esters and nitriles; Addition of Grignard reagents, organozinc and organolithium reagents to carbonyl and unsaturated carbonyl compounds; Wittig reaction; Mechanism of condensation reactions involving enolates – Aldol, Knoevenagel, Claisen, Mannich, Benzoin, Perkin and Stobbe reactions; Hydrolysis of esters and amides; Ammonolysis of esters.
Author: Erich Clar
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 144
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Book Description
Author: Gernot Frenking
Publisher: John Wiley & Sons
ISBN: 3527333142
Category : Science
Languages : en
Pages : 450
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Book Description
This is the perfect complement to "Chemical Bonding - Across the Periodic Table" by the same editors, who are two of the top scientists working on this topic, each with extensive experience and important connections within the community. The resulting book is a unique overview of the different approaches used for describing a chemical bond, including molecular-orbital based, valence-bond based, ELF, AIM and density-functional based methods. It takes into account the many developments that have taken place in the field over the past few decades due to the rapid advances in quantum chemical models and faster computers.
Author: Maya Shankar Singh
Publisher: Pearson Education India
ISBN: 9788131711071
Category : Chemistry, Organic
Languages : en
Pages : 532
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Book Description
Advanced Organic Chemistry: Reactions and Mechanisms covers the four types of reactions -- substitution, addition, elimination and rearrangement; the three types of reagents -- nucleophiles, electrophiles and radicals; and the two effects -- electroni.
Author: Jerome A. Berson
Publisher: Wiley-VCH
ISBN:
Category : Science
Languages : de
Pages : 216
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Book Description
Jerome A. Berson Chemical Creativity Ideas from the Work of Woodward, Hückel, Meerwein, and Others How did the pioneers in chemistry recognize the fundamental intellectual issues of their time? What skills of reasoning and experiment did they use to solve these problemes? How did the circumstances of personality and competition influence their careers and scientific accomplishments? If we can answer these questions, we may be able to improve our own chances of success in research. »This is a marvelous book of people and chemical ideas! The author, Jerry Berson, is known as a chemical stylist, a physical organic chemist possessed of the highest analytical powers. In a unique approach to the history of chemistry (indeed the history of science) he brings that style, as well as his insider’s knowledge and a perceptive sensivity to the societal setting of chemists, to the analysis of some key chapters in modern organic chemistry.« Roald Hoffmann, Nobel Laureate
Author: Vladimir I. Minkin
Publisher: Wiley-Interscience
ISBN:
Category : Science
Languages : en
Pages : 344
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Book Description
Designed to assist chemists in integrating the results of calculations on molecules and ions into their general body of chemical knowledge. Contains recent contributions from theoretical and computational chemistry to the development of the concept of aromaticity (antiaromaticity) and its expansion into new areas such as organometallic and cluster compounds and three-dimensional structures. Updates the modern status of aromaticity and covers basic principles and experimental applications.
Author: James P. Snyder
Publisher: Elsevier
ISBN: 1483275655
Category : Science
Languages : en
Pages : 449
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Book Description
Nonbenzenoid Aromatics, Volume II, provides an overview of the state of knowledge in the field of non-benzenoid aromatic compounds. The theme that threads its way through the six chapters is that of ""aromaticity,"" with each author making an effort to evaluate this concept in light of his own work. It is with this in mind that this treatise was initiated with an historical account tracing the development of the idea up to the discovery of the electron. The book begins with discussions of the estimation of the thermochemical and kinetic stability of a system which has not yet been synthesized and the calculation of electronic spectra. This is followed by separate chapters on the electron spin resonance (ESR) spectra of radical ions of nonbenzenoid aromatics; the theoretical and empirical bases of exaltation; and treatment of cyclic (4n + 2) p-electron systems with six or more p-electrons and bearing one or more formal charges. Subsequent chapters deal with the chemical binding and delocalization in phosphonitrilic derivatives, and cyclobutadiene-metal complexes.
