Organic Chemistry GENERAL CONCEPTS

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. 

A few words about the pattern of organization of this chapter. The theoretical studies are included in Section II. In Section VII some interesting chain reactions involving sulfonyl radicals are discussed, although often one of the propagation steps is treated earlier in Section IV or V. Finally, some general concepts of free radical chemistry are introduced at appropriate points throughout the review without any reference. 

This author is perfectly aware that he could add very little to the work done by these workers if an attempt was made to focus on intramolecular catalysis phenomena or on the relevance to cyclisation of available models of chain conformation and chain dynamics instead, the aim will be the presentation of a general treatment of the subject, namely, one that includes the cyclisation of very short chains as well as that of very long chains of, say, 100 atoms or more. With a subject as vast as this, an encyclopaedic review would be a hopeless task. Therefore, the subject will be treated in a systematic and critical way, with more concentration on reaction series with regular and wide variations in structure, rather than on scattered examples. The aim will be to show that the field of intramolecular reactions is a mature area in which the merging of concepts from both physical organic chemistry and polymer chemistry leads to a unified treatment of cyclisation rates and equilibria in terms of a few simple generalisations and theories. 

A complete structural analysis can sometimes be accomplished by a study of the fragmentation pattern. Some general rules for the modes of fragmentation expected from particular types of compound are formulated on the basis of the concepts of physical and organic chemistry. These are ... 

Concept Phase transfer catalysis (PTC)111 is now a convenient and useful tool in chemistry, especially in preparative organic chemistry. In general, compounds (reactants) located in different phases of a reaction mixture such as water and benzene sluggishly react each other even by harsh stirring the mixture because the reactants can not easily contact together. Phase transfer catalysts transfer between different phases, become highly active species, and catalytically medi-... 

This study examined some unexplored aspects of conceptualization in organic chemistry. How are classificatory concepts created Can the value of a generalization be quantified Although here these questions are presented in relation to organic chemistry, they are in fact basic questions of epistemology and go beyond organic chemistry.(9)... 

The question of protonation sites is one of the basic questions in the behaviour of complex organic molecules in solution, since protonated molecules are intermediates in synthetic organic chemistry, and the knowledge of protonation sites is important for the theory of reaction mechanisms of acid-catalysed reactions. It is also of fundamental importance for structural theory in general, since it is intimately connected with the concepts of mesomerism, electron density and bond polarization. 

OIML - International Organization of Legal Metrology (www.oiml.org) lUPAP - International Union of Pure and Applied Physies (www.iupap.org) IFCC - International Federation of Clinieal Chemistry (www.ifcc.org/ifcc.asp) VIM - International Vocabulary of Metrology - Basic and General Concepts and associated Terms... 

The concept of a group is especially important in organic chemistry. A functional group represents a set of atoms that is closely linked with chemical reactivity and defined classes of substances. For instance, the functional group hydroxyl, -OH, is characteristic of the classes alcohol, phenol and enol. Alcohols are often represented by the general formula R-OH, in which R- represents a hydrocarbon group typical of aliphatic and alicyclic substances. 

Structure-Activity Relationships. More interesting, and -scientifically, at least - more significant, is the question of why one nitrosamine should be more or less carcinogenic than another. In a general sense, the answer is obvious differences in reactivity within a series are, almost by definition, the result of differences in structure. This concept is one of the cornerstones of physical organic chemistry and, more recently, has been applied extensively to drug systems in a systematic and quantitative way following the initial and continued successes of Corwin Hansch and his coworkers (18-25). 

The concept of a reaction co-ordinate in organic chemistry is one that is not simply defined, since for a polyatomic system of n atoms it may depend on as many as 3n — 6 parameters for complete characterization. The reaction co-ordinate used by organic chemists in their representation of a reaction profile has only a qualitative significance. For example, that for an SN2 process on a methyl derivative is generally equated with the change in either the... 

A number of general rules for predicting prominent peaks in El spectra can be written and rationalized by using standard concepts of physical organic chemistry. 

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