Reactions - General Introduction

Compounds with a terminal triple bond can undergo a Mannich condensation with formaldehyde and secondary aliphatic or alicyclic amines [193], 

Pure dioxane (70 ml) and powdered paraformaldehyde (30 g, corresponding to 1 mol of the monomer) are placed in the flask. Liquified dimethylamine (-0,3 mol), or diethylamine (-0,3 mol) is added at room temperature. The temperature of the mixture rises gradually to - 45 C. After cooling to room temperature, a second portion of - 0.3 mol of the amine is added. When the ensuing exothermic reaction has subsided, the remainder of the 1.2 mol of the amine is added at - 20 C. The conversion is completed by heating the mixture for 30 min at - 50 C. A slightly turbid solution is formed. 

Apparatus 1-1 three-necked, round-bottomed flask, equipped with a gas inlet tube (reaching beneath the surface of the solution), a gas-tight mechanical stirrer and a reflux condenser, the inlet tube is connected with a trap containing the liquified acetylene, and the top of the condenser with a trap placed in a bath at -78 C all connections are fixed well and made 

In the cases of the lower homologues, which have a reasonably good solubility in water, several extractions with Et20 have to be carried out. The presence of insoluble copper compounds may give rise to difficulties with the separation of the layers. 

In view of serious foaming, a relatively large distillation flask is used. 

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Charge diagrams suggest that the 2-amino-5-halothiazoles are less sensitive to nucleophilic attack on 5-position than their thiazole counterpart. Recent kinetic data on this reactivity however, show, that this expectation is not fulfilled (67) the ratio fc.. bron.c.-2-am.noih.azoie/ -biomoth.azoie O"" (reaction with sodium methoxide) emphasizes the very unusual amino activation to nucleophilic substitution. The reason of this activation could lie in the protomeric equilibrium, the reactive species being either under protomeric form 2 or 3 (General Introduction to Protomeric Thiazoles). The reactivity of halothiazoles should, however, be reinvestigated under the point of view of the mechanism (1690). 

Introduction Many present-day commercial gas absorption processes involve systems in which chemical reactions take place in the liquid phase. These reactions generally enhance the rate of absorption and increase the capacity of the liquid solution to dissolve the solute, when compared with physical absorption systems. 

The Sandmeyer reaction generally permits the introduction of electron-withdrawing substituents onto an aromatic ring. Arenediazonium salts, as well as the Sandmeyer products derived thereof, are useful intermediates for the synthesis... 

The book commences with a general introduction outlining the basic concepts. This is followed by a chapter on radical reactions that is intended to lay the theoretical ground-work for the succeeding chapters on initiation, propagation, and termination. Because of its importance, radical copolymerization is treated in a separate chapter. We then consider some of the implications of these chapters by... 

In this section a general introduction to homolytic dediazoniation of arenediazonium salts is given, with some representative examples. The following sections of this chapter first describe reaction conditions for observing the changeover from hetero-... 

Nor has a general introduction to the microchemical postchromatographic reactions been omitted it makes up the second part of the book. 

This article is an attempt at evaluating new important features of tin(II) chemistry the central point is the interrelationship between molecular structure and reactivity of molecular tin(II) compounds. To define these compounds more closely, only those are discussed which are stable, monomeric in solvents and which may be classified as carbene analogs21. Thus, not a complete survey of tin(II) chemistry is given but stress is laid on the structures and reactions of selected compounds. A general introduction to the subject precedes the main chapters. For comparison, also solid-state tin(II) chemistry is included to demonstrate the great resemblance with molecular tin(II) chemistry. Tin(II) compounds, which are either generated as intermediates or only under definite conditions such as temperature or pressure, are not described in detail. 

Chapter 2 provided a general introduction to the a-alkylation of carbonyl compounds, as well as the enantioselective nucleophilic addition on carbonyl compounds. Chiral auxiliary aided a-alkylation of a carbonyl group can provide high enantioselectivity for most substrates, and the hydrazone method can provide routes to a large variety of a-substituted carbonyl compounds. While a-alkylation of carbonyl compounds involves the reaction of an enolate, the well known aldol reaction also involves enolates. 

Chapters 2 through 6 introduced many asymmetric organic reactions catalyzed by small molecules, such as C-C bond formation, reduction, and oxidation reactions. Chapter 7 provided further examples of how asymmetric reactions are used in organic synthesis. This chapter starts with a general introduction to enzyme-catalyzed asymmetric organic reactions. 

Bott, A.W., Practical problems in voltammetry. 3 Reference electrodes for voltammetry . Current Separations, 14, 64-68 (1995) is an excellent first stop for the novice, as is Bott, A. W Characterization of chemical reactions coupled to electron-transfer reactions using cyclic voltammetry . Current Separations, 18, 9-16 (1999), which also introduces simulations. In addition, the article by Hitchman and Hill in Chemistry in Britain (see above) contains a low-level general introduction to cyclic voltammetry for analyses. 

With this general introduction as background, we will focus on the pre-association mechanisms in decarboxylation reactions, an area where such a possibility has only been recently recognized. 

This is an easy-to-read text which provides a general introduction to the area of macrocyclic chemistry and has much to say about template reactions. 

Part I gives a general introduction and presents the theoretical, methodological and experimental aspects of thermal risk assessment. The first chapter gives a general introduction on the risks linked to the industrial practice of chemical reactions. The second chapter reviews the theoretical background required for a fundamental understanding of mnaway reactions and reviews the thermodynamic and kinetic aspects of chemical reactions. An important part of Chapter 2 is dedicated to the heat balance of reactors. In Chapter 3, a systematic evaluation procedure developed for the evaluation of thermal risks is presented. Since such evaluations are based on data, Chapter 4 is devoted to the most common calorimetric methods used in safety laboratories. 

The book is organized into sections that relate either to a compound or reaction type, as outlined in the table of contents. When there are several chapters on a specific topic, the first chapter of that section is a general introduction. 

This review is divided into three parts. For a general introduction to the topic see Sects. 1 and 2 in Part 1. The basic reactivity patterns and the general methods to conduct radical-catalyzed reactions and to analyze the involved intermediates are discussed there. Processes catalyzed by metals of group 4 to group 7 are reviewed in... 

Reactant Introduction Methods The batch reactor is generally heated once the reactants mixture has been added. A flash introduction of the reactant, previously brought to the reaction temperature can be envisaged. However, in order to control the starting time of the reaction, flash introduction of catalyst may alternatively be used. 

For a general introduction to the aldol reaction, see March, J. Advanced Organic Chemistry, 4th ed. Wiley New York, 1992 pp. 937-944. 

This review is written to cover the needs of synthetic chemists with interests in oxidizing alkenes by addition of nitrogenous substituents. Whilst some aspects have been covered in previous reviews (noted in the text), most notably in the Tetrahedron Report No. 144, Amination of Alkenes and prior reviews on aziridines and nitrenes, the present review is the fust conq>ilation of references to the whole range of these particular bond-forming processes. A review by Whitham provides a useful general introduction to reaction mechanisms of additions to alkenes in greater detail than can be covered here. The oxidation requirement excludes from the scope the additions of N H and most additions of N + Metal or N + C. Hence, unmodified Michael and Ritter reactions are excluded. These topics are mostly covered in Volume 4 of the present series. 

The discovery of hydroboration reactions by Brown has greatly advanced the field of organoboron chemistry, and this reaction remains one of the most important and versatile synthetic routes to organoboron compounds. Many excellent reviews and book chapters on this topic have appeared in the literature. " Thus, only a brief general introduction and... 

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