Organic chemistry general principles

All of the material in this text and most of chemistry generally can be understood on the basis of what physicists call the electromagnetic force Its major principle is that opposite charges attract and like charges repel As you learn organic chemistry a good way to start to connect structure to properties such as chemical reactivity is to find the positive part of one molecule and the neg ative part of another Most of the time these will be the reactive sites... 

The photochemical reactions of organic compounds attracted great interest in the 1960s. As a result, many useful and fascinating reactions were uncovered, and photochemistry is now an important synthetic tool in organic chemistry. A firm basis for mechanistic description of many photochemical reactions has been developed. Some of the more general types of photochemical reactions will be discussed in this chapter. In Section 13.2, the relationship of photochemical reactions to the principles of orbital symmetry will be considered. In later sections, characteristic photochemical reactions of alkenes, dienes, carbonyl compounds, and aromatic rings will be introduced. 

The goal of this text is to build on the foundation of introductory organic chemistry to provide students and other readers a deeper understanding of structure and mechanism and the relationships between them. We have provided specific data and examples with which to illustrate the general principles that are discussed. Our purpose is to solidify the student s understanding of the basic concepts, but also to illustrate the way specific structural changes influence mechanism and reactivity. 

The Lead-Off Reaction Addition of HBr to Alkenes Students usually attach great-importance to a text s lead-off reaction because it is the first reaction they see and is discussed in such detail. 1 use the addition of HBr to an alkene as the lead-off to illustrate general principles of organic chemistry for several reasons the reaction is relatively straightforward it involves a common but important functional group no prior knowledge of stereochemistry or kinetics in needed to understand it and, most important, it is a polar reaction. As such, 1 believe that electrophilic addition reactions represent a much more useful and realistic introduction to functional-group chemistry than a lead-off such as radical alkane chlorination. 

To conclude this section, we can state that all of the theories presented hitherto, even when starting from general principles, inevitably embody several assumptions, which in fact represent the heart of the analysis. However, the physical meaning of these assumptions usually is not known, so that no theory is able to predict in which reaction series isokinetic behavior appears and in which it does not. Neither is the structural theory of organic chemistry able to make such a prediction and to define the terms reaction series or similar reactions or small structure changes it can only afford many examples. 

The joint memoirs of Prevost and Kirrmann self-consciously presented a general theory of organic chemistry that constituted an application of physical methods and principles to the problem of organic reaction mechanisms. However, the language system devised by Prevost and Kirrmann was not adopted by chemists in general, and that part of their notation which was new was not used outside France. Indeed, there was very little interest in their work inside France. 

Dewar, M. J. S. A Molecular Orbital Theory of Organic Chemistry, I. General Principles. J. Amer. chem. Soc. 74, 3341 (1952). 

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