Representative-group chemistry

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. 

Most inorganic research involves work with small molecules, and relatively little concentrated effort has been devoted to the macromolecular aspects of the subject. The complexity of the macromolecular chemistry has undoubtedly contributed to this neglect. However, it is clear from recent work that dramatic advances in both fundamental science and technology would be possible if the high polymer chemistry of the representative elements were to be studied in detail. Indeed, the much-heralded renaissance in Main Group chemistry may ultimately depend on a closer Investigation of the macromolecular aspects of the field. 

The number of compounds (n) used to derive the regression equation, as well as the correlation coefficient (r) and standard error (s), appear above. Cramer (1980a) gives the 114 compounds used to derive Equation (6). This set appears too small to allow a broad range of chemical class applicability. Cramer himself notes that the compound set is not representative of chemistry as a whole, that most are liquids, none are ionic structures, and few are multifunctional or higher molecular weight substances. Nevertheless, the list does represent a fairly diverse group of chemical classes. Note that the value for "molecule," listed at... 

The SFC separation of nonsteroidal anti-inflammatory drugs (NSAIDs) was investigated by Jagota and Stewart [6]. These compounds vary in chemical structure and functional group chemistry and provide a representative sample of acidic drugs to study. Using a 10-m x 50-fim ID... 

Protection of the amide — NH is an area of protective group chemistry that has received little attention, and as a consequence few methods exist for amide —NH protection. Most of the cases found in the literature do not represent protective groups in the true sense, in that the protective group is often incoiporated as a handle to introduce nitrogen into a molecule rather than installed to protect a nitrogen which at some later time is deblocked. For this reason many of the following examples deal primarily with removal rather than with both formation and cleavage. 

These elements are a diverse bunch, containing as they do metals and nonmetals and, at room temperature and normal pressure, some gases, some liquids, and some solids. Within the representative group are several important families of elements with chemistries all their own. 

Chemical Abstracts (CA) has a large staff of abstractors, well over 2000. These chemists constitute a representative group because all kinds of chemists are needed in approximate proportion to the research activities in the various branches or fields of chemistry. One or more section editors, each well informed in the field of his section, are in charge of the 33 sections and 19 subsections of CA. rhe abstractors and section editors, active specialists in many kinds of chemical work, are often consulted as to matters of policy, so that right in the CA family the editor has users of CA regularly available for consultation and advice. In addition, many others are consulted and many write to tell of their needs. Carefully worded and distributed questionnaires have been sent out from time to time from the CA office. In 1958 a professional information service (Herner Co.) made an extensive interview study of the use of CA. Listening is a source of growth. 

An oversimplified rationale for the special significance of 18 electrons can be made by analogy with the octet rule in main group chemistry. If the octet represents a complete valence electron shell configuration then the number 18 represents a filled valence shell for a transition metal Although perhaps a useful way to relate electron... 

---