Showing papers in "Chemical Reviews in 1991"

A survey of Hammett substituent constants and resonance and field parameters

Abstract: The Hammett equation (and its extended forms) has been one of the most widely used means for the study and interpretation of organic reactions and their mechanisms. Although the Hammett methodology has been criticized by theoreticians because of its empirical foundation, it is astonishing that u constants, obtained simply from the ionization of organic acids in solution, can frequently predict successfully equilibrium and rate constants for a variety of families of reactions in solution. Almost every kind of organic reaction has been treated via the Hammett equation, or its extended form. The literature is so voluminous and extensive that there is no complete review of all that has been accomplished. Hammett's success in treating the electronic effect of substituents on the rates and equilibria of organic reactions1P2 led Taft to apply the same principles to steric and inductive and resonance effects? Then, more recently, octanol/ water partition coefficients (P) have been used for rationalizing the hydrophobic effects of organic compounds interacting with biological systems? The use of log P (for whole molecules) or n (for substituents), when combined with electronic and steric parameters, has opened up whole new regions of biochemical and pharmacological reactions to study by the techniques of physical organic chemistry.sf3 The combination of electronic, steric, hydrophobic, hydrophilic, and hydrogen-bonding7 parameters has been used to derive quantitative structure-activity relationships (QSAR) for a host of interactions of organic compounds with living systems or parts thereof. The binding of organic compounds to proteins,8 their interaction with enzymess and with cellsloJ1 and tiasues,12 their inhibition of organelles,l' and as antimalarial^'^

The synthetic methodology of nonracemic glycidol and related 2,3-epoxy alcohols

Abstract: Kremzer Chem Abs 95, 1328.18a (1981). Stevens, J Het Chem 20, 295 (1983). Ueda, J Het Chem 8, 827 (1971). Sata, Bull Chem Soc Japan 46, 1572 (1973). Webb, Nucleosides & Nucleotides 8,619 (1989). Terry, Antiviral Res 10, 235-252 (1988). Rosenberg, Coll. Czech Chem. Comm 53, 2753 (1988). Robert M. Hanson, \"The Synthetic Methodology of Nonra cemic Glycidol and Related 2,3-Epoxy Alcohols', Chemi cal Reviews, vol. 91, No. 4, (Jun. 1991) pp. 437-475. Primary Examiner-Mark L. Berch Attorney, Agent, or Firm-Max D. Hensley

Coordination chemistry of lithium ion: a crystal and molecular structure review

Abstract: There has been much recent interest in lithium and lithium ionophores. This growing interest in lithium is mainly due to the actual and potential applications of Li[sup +] in science, medicine, and technology. In the present review article, a tabulation is given, based on X-ray crystallographic data, of the bond lengths, geometry, coordination numbers, and solvent of crystallization of Li[sup +] complexes. The data included in the review extend from the earliest publications through February 1990. The authors have attempted in the text to draw the reader's attention to the various parameters involved in lithium-ligand interaction such as ligand coordination sites, ligand conformation changes, stereochemical arrangement of ligand binding sites, counterion effects, and solvent effects. In addition, discussion is included of lithium selective ionophores and of the involvement of Li[sup +] in biological cycles. Appropriate examples taken from the tables of data are used to illustrate the text. The compounds included in the review are listed by formula and abbreviation in Charts 1--18. The approach the authors chose for this review is a structural one, centered on the examination of the three-dimensional crystal structures of lithium salts and complexes. The basic assumption is that the structures of these lithium complexes more » in the solid state resemble their structures in solution, and that similar structure-selectivity relationships exist, at least to some extent, in both media. 190 refs. « less