Structure and reactivity

Hammen equation A correlation between the structure and reactivity in the side chain derivatives of aromatic compounds. Its derivation follows from many comparisons between rate constants for various reactions and the equilibrium constants for other reactions, or other functions of molecules which can be measured (e g. the i.r. carbonyl group stretching frequency). For example the dissociation constants of a series of para substituted (O2N —, MeO —, Cl —, etc.) benzoic acids correlate with the rate constant k for the alkaline hydrolysis of para substituted benzyl chlorides. If log Kq is plotted against log k, the data fall on a straight line. Similar results are obtained for meta substituted derivatives but not for orthosubstituted derivatives. 

M. P. Pileni, ed.. Structure and Reactivity in Reverse Micelles, Elsevier, New York,... 

McCreery R L, Liu Y-C, Kagen M, Chen P and Fryling M 1996 Resonance and normal Raman spectroscopy of carbon surfaces relationships of surface structure and reactivity ICORS 96 XVth Int. Conf. on Raman Spectroscopy ed S A Asher and P B Stein (New York Wiley) pp 566-7... 

Pople J A 1973 Theoretical models for chemistry Energy, Structure, and Reactivity ed D W Smith and W B McRae (New York Wiley) p 51-67... 

Nonose S, Sone Y, Onodera K and Kaya K 1990 Structure and reactivity of bimetallic Co V Clusters J. Phys. C Solid State Phys. 94 2744... 

The simplest molecular orbital method to use, and the one involving the most drastic approximations and assumptions, is the Huckel method. One str ength of the Huckel method is that it provides a semiquantitative theoretical treatment of ground-state energies, bond orders, electron densities, and free valences that appeals to the pictorial sense of molecular structure and reactive affinity that most chemists use in their everyday work. Although one rarely sees Huckel calculations in the resear ch literature anymore, they introduce the reader to many of the concepts and much of the nomenclature used in more rigorous molecular orbital calculations. 

Molecular orbitals (mos) are formed by combining atomic orbitals (aos) of the constituent atoms. This is one of the most important and widely used ideas in quantum chemistry. Much of chemists understanding of chemical bonding, structure, and reactivity is founded on this point of view. 

R. F. Hout, Jr., W. J. Pietro, W. J. Hehre, A Pictorial Approach to Molecular Structure and Reactivity John Wiley Sons, New York (1984). 

Ridd, J. H. (i960). Studies on Chemical Structure and Reactivity, ed. J. H. Ridd, London Methuen. 

The most notable studies are those of Ingold, on the orienting and activating properties of substituents in the benzene nucleus, and of Dewar on the reactivities of an extensive series of polynuclear aromatic and related compounds ( 5.3.2). The former work was seminal in the foundation of the qualitative electronic theory of the relationship between structure and reactivity, and the latter is the most celebrated example of the more quantitative approaches to the same relationship ( 7.2.3). Both of the series of investigations employed the competitive method, and were not concerned with the kinetics of reaction. 

THEORIES RELATING STRUCTURE AND REACTIVITY 7.2.1 The electronic theory of organic chemistry... 

In this section you have seen how heats of com bustion can be used to determine relative stabilities of isomeric alkanes In later sections we shall expand our scope to include the experimentally determined heats of certain other reactions such as bond dissociation energies (Section 4 16) and heats of hydrogenation (Section 6 2) to see how AH° values from various sources can aid our understanding of structure and reactivity... 

The prefix stereo is derived from the Greek word stereos meaning solid Stereochemistry is the term applied to the three dimensional aspects of molecular structure and reactivity... 

Our first three chapters established some fundamental principles concerning the structure of organic molecules and introduced the connection between structure and reactivity with a review of acid-base reactions In this chapter we explore structure and reactivity m more detail by developing two concepts functional groups and reaction mechanisms A functional group is the atom or group m a molecule most respon sible for the reaction the compound undergoes under a prescribed set of conditions How the structure of the reactant is transformed to that of the product is what we mean by the reaction mechanism... 

Section 20 2 The structure and reactivity of carboxylic acid derivatives depend on how well the atom bonded to the carbonyl group donates electrons to it... 

Structure and reactivity of neutral pyrazole, its anion and its cation... 

Volume 48 Structure and Reactivity of Surfaces. Proceedings of a European Conference, Trieste, September 13-16, 1988 edited by C. Morterra, A. Zecchina and G. Costa Volume 49 Zeolites Facts, Figures, Future. Proceedings of the 8th International Zeolite Conference, Amsterdam, July 10-14,1989. Parts A and B edited by P.A. Jacobs and R.A. van Santen... 

The examples that have been presented in this section illustrate the approach that is used to describe structure and reactivity effects within the framework of MO description of structure. In the chapters that follow, both valence bond theory and MO theory will be used in the discussion of structure and reactivity. Qualitative valence bond terminology is normally most straightforward for saturated systems. MO theory provides useful insights into conjugated systems and into effects that depend upon the symmetry of the molecules under discussion. 

J. H. Ridd, Acc. Chem. Res. 4 248 (1971) J. H. Ridd, in Studies on Chemical Structure and Reactivity, J. H. Ridd, ed., John Wiley Sons, New Vbik, 1966, Chapter 7 J. G. Hoggett, R. B. Moodie, J. R. Penton, and K. Schofield, Nitration and Aromatic Reactivity, Cambridge University Press, Cambridge, 1971 K. Schofield, Aromatic Nitration, Cambridge University Press, Cambridge, 1980 G. A. Olah, R. Malhotra, and S. C. Narang, Nitration, Methods and Mechanisms, VCH Publishers, New i)rk, 1989. 

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