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Chapter

Cover Organic Chemistry

Organic Synthesis  

This chapter looks at the reactions used in organic synthesis. It defines organic synthesis as the directed preparation of a sought compound usually, but not invariably, with some structural complexity from simple, readily available compounds. The chapter also develops the concept of retrosynthesis further and examines how to identify routes for syntheses of target compounds by applying organic reactions. Organic synthesis is one of the ultimate goals of organic chemistry and provides limitless opportunities to challenge the scientific imagination. The chapter then proceeds to discuss the synthons and the corresponding reagents as well as the reaction selectivity. Finally, the chapter elaborates on linear and convergent strategies, and presents some examples of organic synthesis.

Chapter

Cover Organic Synthesis

Introduction to synthesis  

This chapter provides an overview of organic synthesis. The synthesis of a particular compound from commercially available starting materials is fundamental to nearly all aspects of organic chemistry. Thousands of organic compounds are naturally occurring and may be isolated from natural resources such as fungi, bacteria, and plants, but often not in sufficient quantities for a comprehensive study. In addition, many fascinating compounds are not naturally occurring and hence these molecules must be prepared to enable their properties to be investigated. The chapter then looks at bond polarity and free radical reactions. Most organic reactions involve heterolytic cleavage of bonds and reactions between positive or negatively charged or polarized species. However, organic compounds can also become involved in radical reactions, an area which is growing in importance in synthesis.

Chapter

Cover Stereoselectivity in Organic Synthesis

Introduction  

This introductory chapter provides an overview of stereoselectivity in organic synthesis. Given the importance of the three-dimensional structure of organic compounds, and the fact that all organic compounds arise as a result of a previous reaction or reaction sequence, it is not surprising that an area of chemistry which encompasses organic reactions and stereochemistry is central to organic chemistry. This book focuses on the area of stereoselective organic reactions, highlighting their usefulness in organic synthesis where appropriate. For the most part, it is concerned with reactions which involve the formation of tetrahedral carbon atoms within a molecular framework. The chapter then looks at diastereoselective reactions, enantioselective reactions, and stereospecific and stereoselective reactions.

Chapter

Cover Foundations of Organic Chemistry

Mechanisms  

This chapter discusses organic reaction mechanisms, which are shorthand descriptions of how starting compounds are made into products. Molecules with the same functional groups usually react using similar mechanisms, and we can use mechanisms for known reactions to predict how other molecules will behave under similar conditions. Mechanisms are thus a connecting thread between similar reactions and allow us to rationalize the products of a known reaction and to predict the reactivity of other organic molecules. The chapter considers the mechanisms of three types of reaction: substitution, addition, and elimination. It then looks at nucleophiles, electrophiles, and radicals. The chapter also studies the process of drawing mechanisms using dot diagrams and curly arrows.

Chapter

Cover Chemistry3

Organic reaction mechanisms  

This chapter provides the key tools needed to understand and write mechanisms for the reactions of organic molecules and gives an overview of the characteristic reaction mechanisms of common functional groups. A set of guidelines for drawing reaction mechanisms, classifying organic reactions, and determining the different types of selectivity in organic reactions are included. The chapter demonstrates how to use double-headed and single-headed arrows to represent the movement of electrons in polar and radical reactions, respectively. It discusses hyperconjugation, inductive effects, and mesomeric effects that affect the stability of ions and neutral organic molecules and shows the inductive and mesomeric effects of some functional groups. It also compares the relative strengths of nucleophiles and electrophiles.

Book

Cover Stereoselectivity in Organic Synthesis
Stereoselectivity in Organic Synthesis is concerned with the reactions used in stereoselective organic synthesis. It sets out to consider the general principles upon which such reactions are founded, especially stereoelectronic effects, and how these are applied to a wide range of stereospecific and stereoselective organic reactions used in organic synthesis today. The general topics covered include: reactions of carbonyl compounds, aldol reactions, additions to C-C double bonds, oxidation and reduction, rearrangements, and enzyme catalyzed hydrolysis. Reactions whose stereoselectivity is either substrate controlled, reagent controlled or controlled by a catalyst are covered, and where appropriate, examples of their application in organic synthesis are provided.

Chapter

Cover Environmental Chemistry

Microbiological processes  

This chapter highlights the role that microorganisms play in facilitating environmental processes. It considers their role in organic matter degradation processes in terms of their energy relationships. It discusses the important environmental cycles of carbon, nitrogen, and sulfur and looks at the classification systems and properties of microorganisms. It also clarifies that abiotic reactions occur through purely physical or chemical means that can take place in a completely sterile environment while biotic reactions have a biological component. The chapter points out that the biological component of biotic reactions typically involves microorganisms. Biota classified as microorganisms are often very small, with dimensions frequently in the micrometre size range. The chapter highlights that microorganisms, despite their small size, play an essential role in facilitating many chemical reactions that occur in the natural environment, such as the process through which ammonium ion is converted to nitrate in water or soil.

Book

Cover Organic Synthesis
Organic Synthesis describes the properties and reactions of organoboranes and organosilanes, emphasizing how they can be used to provide simple solutions to a variety of synthetic problems. Compounds of boron and silicon are widely used in organic synthesis, and their study forms a core in many chemistry courses. Helpful study questions are provided at the end of each section, and the suggested further reading provides a useful guide to more advanced work in the field.

Book

Cover Organometallic Reagents in Synthesis
Organometallic Reagents in Synthesis looks at the properties and reactions of main group organometallic compounds, placing particular emphasis on their applications in synthesis. The book adopts a logical approach to this area of organic chemistry, and provides an account of all aspects of the field. Study problems are included at chapter ends, along with suggestions for further reading on the topic.

Chapter

Cover Organic Chemistry

Nucleophilic Addition to the Carbonyl Group in Aldehydes and Ketones  

This chapter discusses the polarity of the carbonyl bond and the catalysis of nucleophilic addition to carbonyl groups by acids and bases. It considers in detail the reactions of a functional group, and looks at nucleophilic additions to the carbonyl group of aldehydes and ketones. The chapter argues that these reactions provide clear examples of several fundamental principles of organic reaction mechanisms, and they also include some of the most useful reactions for organic synthesis. The carbonyl (>C=O) group is a functional group found in aldehydes and ketones as well as carboxylic acids and their derivatives, and is one of the most important in organic and biological chemistry. The chapter ends by explicating the acetal and dithioacetal formation as well as the Wittig reaction. It also investigates the formation of imines and enamines.

Chapter

Cover Structure and Reactivity in Organic Chemistry

Organic reaction mechanisms and reaction maps  

This chapter discusses organic reaction mechanisms and reaction maps. Collisions between molecules provide the energy for bimolecular and unimolecular thermal reactions to occur. In a bimolecular reaction, three translational and (normally) up to three rotational degrees of freedom are lost in the formation of the activated complex; since the total has to remain the same, a corresponding number of new vibrational degrees of freedom are formed. In a unimolecular reaction, a molecular collision leaves one of the molecules in a vibrationally excited state which either reacts or simply loses its excess energy in a subsequent collision. The chapter then looks at molecular vibrations and potential energy diagrams. It also considers parallel and perpendicular effects; step-wise reactions; and single-step multibond cycloaddition reactions.

Chapter

Cover Organic Stereochemistry

Introduction: development of methods and concepts in organic stereochemistry  

This chapter introduces the development and benefits of organic stereochemistry. It offers a brief survey of the history of organic stereochemistry to about 1960 and presents many of the more important terms used in organic stereochemistry. The chapter opens with the discussion about shapes of molecules and optical activity in organic liquids which was taken by Fresnel. It also explores Pasteur’s recognition of enantiomerism in tartaric acids–emphasizing the three known tartaric acids. Towards the end, the chapter turns to explanations by Van't Hoff and Le Bel of the existence of pairs of enantiomeric molecules. It also looks at the two notable lactic acids, which come from milk and from muscle. It concludes by presenting some reaction sequences and explores the study of organic reaction mechanisms.

Chapter

Cover Making the Transition to University Chemistry

Introduction to Organic Chemistry  

This chapter introduces organic chemistry. This type of chemistry involves the study of compounds formed by carbon. The chapter highlights how living organisms are mainly composed of carbon compounds. Structural formula shows exactly which atoms are bonded together. A homologous series is a collection of molecules with the same functional group differing only in the number of carbon atoms present. The chapter discusses the IUPAC nomenclature for the alkane molecules. It also examines the major classes of isomers: structural isomers and stereoisomers. Organic reactions are classified as either radicals, nucleophiles, or electrophiles. The functional group level of a particular carbon atom establishes the number of bonds to the atom that is more electronegative than carbon.

Chapter

Cover Foundations of Organic Chemistry

Acids and bases  

This chapter examines acids and bases. The Brønsted–Lowry theory states that acids are proton donors, and bases are proton acceptors. Acid/base reactions are largely equilibria and are therefore under thermodynamic control. Many organic acids, such as ethanoic acid, are weak acids. The equilibrium constants are small, much less than 1, and remarkably little of the acid donates its proton to water in aqueous solution. Moreover, many organic acids and bases are largely insoluble in water. The chapter then considers the reactivity of bases as leaving groups and nucleophiles, before comparing acid strengths and base strengths. It also looks at amino acids, which are the building blocks of proteins; they are compounds which have major structural and catalytic roles in all living organisms.

Chapter

Cover Radical Chemistry: The Fundamentals

Introduction  

This chapter defines radical, which designates some polyatomic fragment of a molecule that remains unchanged during one or more chemical transformations. The chapter also cites ethyl as a modern example of an organic radical that is unaltered throughout the sequence of changes. It reviews some of the earliest evidence that electrically neutral carbon-centered radicals may be considered important intermediates in organic chemistry. It also talks about the gas-phase chlorination of methane which was interpreted in the early 1930s in terms of a radical mechanism. The chapter describes molecular entities containing an unpaired electron, such as metal ions and alkali-metal atoms. These would not normally be regarded as radicals. It analyzes halogenation reactions, which are among the most familiar of simple radical-mediated processes.

Book

Cover Organic Stereochemistry

Michael J.T. Robinson

Organic Stereochemistry starts by introducing the many common stereochemical terms used throughout the book. The second chapter is an account of the structures of simple unstrained organic molecules followed by examples of strained molecules. The third chapter deals with conformational analysis of acyclic and carbocyclic molecules, ending with a short exposition of molecular mechanics. The fourth chapter is about stereoisomerism in molecules and compounds. A full description of enantiomerism and diastereomerism is followed by an explanation of the nomenclature for absolute and relative configurations of molecules and for topism. A short chapter that follows then describes racemates, their resolution, and methods for determining enantiomeric purity. The book concludes with a survey of stereoselective and stereospecific reactions, including the use of chiral catalysts and auxiliaries, rules for predicting stereoselectivity, and double asymmetric synthesis.

Chapter

Cover Pericyclic Reactions

Cycloaddition reactions  

This chapter considers cycloadditions as the most useful of all pericyclic reactions in organic synthesis. It describes the wide range of known cycloadditions, identifies the conditions under which they take place, draws attention to their regio- and stereochemistry, and gives the simple rules for which of them take place and which do not. It also mentions the most important type of cycloaddition, the Diels–Alder reaction, which is essentially the reaction between butadiene and ethylene which form cyclohexene. The chapter talks about the carbonyl group, which is a substituent attached to the periphery that affects the rate but does not change the fundamental nature of the reaction. It refers to dipoles which react with alkenes or alkynes, or with heteroatom-containing double and triple bonds that form heterocyclic rings.

Book

Cover Organic Chemistry

Jonathan Clayden, Nick Greeves, and Stuart Warren

Organic Chemistry begins with the question: what is organic chemistry? Topics covered include organic structures, molecular structures, organic reactions, nucleophilic substitution, and stereochemistry. There are also chapters on conformational analysis, elimination reactions, formation and reactions of enols and enolates, and chemoselectivity. The text moves on to consider regioselectivity, alkylation and reaction of enolates, retrosynthetic analysis, and aromatic horocycles. There is also coverage of stereoselectivity, diastereoselectivity, pericyclic reactions, and radical reactions. Finally, towards the end, the text looks at synthesis and reactions of carbenes, how to determine reaction mechanisms, organometallic chemistry, asymmetric synthesis, and organic chemistry today.

Book

Cover Oxidation and Reduction in Organic Synthesis
Oxidation and Reduction in Organic Synthesis looks in detail at the topic of organic synthesis. The manipulation of functional groups by oxidative or reductive processes is central to organic chemistry, the text argues. This book provides a clear summary of oxidative and reductive processes, emphasizing general principles and common factors, and shows the applications of these reactions in organic synthesis. After an initial introduction, chapters cover enaitioselective oxidation, oxidation reactions in synthesis, reduction reactions, and enaitioselective reduction.

Chapter

Cover Mechanisms of Organic Reactions

Description and investigation of organic reaction mechanisms  

This chapter discusses the terminology necessary for describing mechanisms of reactions of organic compounds. Each individual step of a complex reaction that is a proper chemical reaction in its own right is called an elementary reaction. As the concerted bonding of the nucleophile and unbonding of the nucleofuge, the molecular potential energy of the ion–molecule system increases until, at a certain stage, it reaches a maximum with both halogen atoms partially bonded to the carbon which is penta-coordinate. The chemical species corresponding to the molecular potential energy maximum is called the activated complex. The chapter then looks at molecularity, reaction coordinate, molecular potential energy reaction profile, and reaction maps. It also introduces the main techniques deployed in the investigation of organic reaction mechanisms, which can be divided into two groups: kinetics methods and non-kinetics methods.