66287 - Reaction Mechanisms

Course Unit Page


This teaching activity contributes to the achievement of the Sustainable Development Goals of the UN 2030 Agenda.

Good health and well-being Affordable and clean energy

Academic Year 2021/2022

Learning outcomes

At the end of the class the student will be able of using the most common tools of physical organic chemistry (transition state theory, chemical kinetics, free energy relationships, isotopic effects…) and theoretical organic chemistry (frontier orbital theory, Woodward-Hoffmann theory, valence-bond theory) to understand the mechanism of organic reactions.

Course contents

Reaction Mechanism. Experimental methodologies used for the determination of reaction mechanisms. Born-Oppenheimer approximation. Potential energy surface (PES). Mathematical description of a PES for structural and reactivity problems in organic chemistry. How to represent a PES: cross sections, More O'Ferrall diagrams. Principles of chemical kinetics. Arrhenius equation. Transition state theory. Volumetric reaction profiles. Uses of isotopic labeling for determination of reaction mechanisms. Isotope effects. Primary isotope effect. Secondary isotope effect. Isotope labelling. Substituent Effects. Free energy relationships. Hammett equation and plots. Two parameters equation. Perturbation methods in organic chemistry: the PMO (Perturbation Molecular Orbital) method. Klopman - Salem equation. HSAB theory in organic chemistry: understanding HSAB theory using the PMO approach. Application of PMO theory to organic reactivity: the FMO ((Frontier Molecular Orbital) approximation. Substitution nucleophilic reactions at the sp3 carbon, electrophilic aromatic substitution and Diels-Alder. Pericyclic reactions (cycloaddition, electrocyclic, sigmatropic, chelotropic reactions): basic notions. Woodward-Hoffmann rules for  electrocyclic and cycloaddition reactions. FMO theory for electrocyclic, cycloaddition, sigmatropic and chelotropic reactions. Non-standard catalysis: light, electromagnetic fields, nanoconfinement. A detailed comparison between theory and experiments for model  reactions.


Teacher notes. Papers available in literature



Teaching methods

Lectures. Problem solving in the classroom

Assessment methods

The goal of the oral examination can be summarized as follows:
(i) the student must possess a good knowledge of the main tools (experimental and theoretical) that allow to understand the topology of a reaction surface.
(ii) the student must be able to use the above concepts to discuss simple examples of organic reactivity.

Teaching tools

Problem solution in the classroom and discussion of examples from the literature.

Office hours

See the website of Matteo Calvaresi