Physical organic chemistry

Physical organic chemistry is the study of the interrelationships between structure and reactivity in organic molecules. [Eric V. Anslyn, Dennis A. Dougherty. "Modern Physical Organic Chemistry". University Science, 2005. ISBN 1891389319.] It can be seen as the study of organic chemistry using tools of physical chemistry such as chemical equilibrium, chemical kinetics, thermochemistry, and quantum chemistry. The term "physical organic chemistry" is commonly attributed to Louis Hammett, who used it as a title for a book in 1940. [Gerrylynn K. Roberts, Colin Archibald Russell. "Chemical History: Reviews of the Recent Literature". Royal Society of Chemistry, 2005. ISBN 0854044647.]

The two main themes in physical organic chemistry are structure and reactivity. The study of structure starts from chemical bonding, with special emphasis on the stability of organic molecules due to factors such as steric strain and aromaticity. Other topics in structure include stereochemistry and conformational analysis. Supramolecular structure is also considered in terms of intermolecular forces including hydrogen bonding. Finally, the acid-base chemistry of the molecules is studied in terms of structure, based on resonance and inductive effects and through the use of linear free-energy relations.

on organic reactions.

Structure and reactivity are both involved in the study of reaction intermediates—the transient species involved in reaction mechanisms. The main types of intermediates of interest are carbocations, carbanions, free radicals, and carbenes. Usually, these intermediates are not isolated, but their presence is inferred from stereochemical evidence, spectroscopy, or through the use of chemical traps. In some cases, however, it is possible to isolate these types of molecules at very low temperatures (cryochemistry) or via matrix isolation. It is also possible to create specific derivatives that are stabilized through chemical means such as resonance, as in the case of the triphenylmethyl radical.

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