Chemical Reaction Mechanisms


It is of interest to use a mechanistic approach which permits the use of a small number of principles derived from a large amount of data to explain and predict experimental results and the consequences of altering conditions for known reactions. Small molecules are typically used for this purpose but the use of biologically important molecules could alert us to some specific characteristics of living systems.


General characterization





Responsible teacher

Paula Cristina de Sério Branco


Weekly - 4

Total - 63

Teaching language





Felix A. Carroll, Perspectives on Structure and Mechanism in Organic Chemistry, Wiley, 2010.

P. A. Sykes, A Primer to Mechanism in Organic Chemistry, Longman Scientific & Technical: Essex, 1995.

H. Maskill, Mechanisms of Organic Reactions, Oxford Chemistry Primers, 45, ed. S. G. Davies: Oxford Science Pub., Oxford Univ. Press, 1996.

P. A. Sykes, A Guidebook to Mechanism in Organic Chemistry, 6 ed., Longman, 1985.

Teaching method

Distance learning with interactive synchronous classes based on web seminars previously made available to students. Synchronous classeswill be aimed at discussing the materials available (theorical class) and at solving in groups the exercises available and intended to apply the previous concepts using practical examples of elucidation of mechanisms taken from basic literature (TP class, of mandatory frequency).

Evaluation method

2 partial tests (October 30 and January 8) or final exam.

Subject matter

Revision of some basic principles Structure and Reactivity. Thermodynamic and kinetic effects associated with reaction mechanisms. Elementary reactions, concerted mechanisms, activated complex, transition state, molecularity, Reaction coordinates, kinetic and thermodynamic control, Hammond postulate. Stability of ionic intermediates, leaving groups, nucleophiles, electrophiles, acids and bases. Acid/base characteristics. Methods for investigating reaction mechanisms; kinetic and non-kinetic. Ionic intermediates. Study and Determination of Reaction Mechanisms Mechanism and molecular orbitals. Stereoelectronic effects. Reactions involving nucleophiles and bases. Reactions involving electrophiles and acids. Reactions involving neutral reactive species (carbenes, nitrenes, Arynes and free radicals. Rearrangments (pinacol, Curtius, Favorski, Baeyer-Villiger, Beckmann) and intermediates containing electron deficient nitrogen and oxygen atoms. Annomeric effect. Reactions without intermediates (concerted pericyclic reactions). Mechanisms in aromatic systems. Mechanisms in radical reactions. Cyclisation reactions (Baldwin rules). Ex. of mechanisms in biological systems.