Chemical Reaction Mechanisms
Code
10710
Academic unit
Faculdade de Ciências e Tecnologia
Department
Departamento de Química
Credits
6.0
Teacher in charge
Maria Teresa Barros Silva
Weekly hours
4
Teaching language
Português
Objectives
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.
Prerequisites
Extensive knowledge in Organic chemistry, Introduction to physical chemistry and thermodynamics. Stereochemistry.
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.
Bibliography
P. A. Sykes, A Guidebook to Mechanism in Organic Chemistry,7 ed., Longman, 1980. H. Maskill, Mechanisms of Organic Reactions, Oxford Chemistry Primers, 45, ed. S. G. Davies: Oxford Science Pub., Oxford Univ. Press, (1996). C. J. Moody, G.H. Whitham, Reactive Intermediates, Oxford Chemistry Primers, 8, ed. S. G. Davies: Oxford Science Pub., Oxford Univ. Press, (1992). J. Jones, Core Carbonyl Chem., Oxford Chemistry Primers, 47, ed. S. G. Davies: Oxford Science Pub., Oxford Univ. Press, (1997). A. J. Kirby, Stereoelectronic Effects, Oxford Chem. Primers, 36, ed. S. G. Davies: Oxford Science Pub., Oxford Univ. Press, (1996). M. Sainsbury, Aromatic Chemistry, Oxford Chem. Primers, 4, ed. S. G. Davies: Oxford Science Pub., Oxford Univ. Press, (1992). L. M. Harwood, Polar Rearrangements, Oxford Chemistry Primers, 5, ed. S. G. Davies: Oxford Science Pub., Oxford Univ. Press, (1992). H.Lowry and K.S. Richardson , Mechanism and Theory in Organic Chem., 3rd edition, Harper e Row Pub., 1987.
Teaching method
Theoretical lectures are given in way to avoid monotony. During the lectures experimental results are used to demonstrate concepts which exemplify the importance of the understanding of chemistry. Problems sessions are an essential part of the course and at least four hours per week are dedicated to this. Although in the first sessions the lecturer leads the students into discussions it is expected that later the students will be encouraged take over this initiative.
When justified molecular models are used as a visual aid. 3D graphics and other audio-visual aids are used whenever possible.
Problem sessions are also very important for the lecturer to identify difficulties that the students may have in their understanding and to find solutions to these difficulties by discussion. This is done in such a way that the high level of the course is maintained
Students have access to a web page created on the moodle platform where they will find online weekly tests and support documents for the theoretical and TP classes.
Evaluation method
Besides the official exams, there will be continuous evaluation with two main tests and two mini tests during the semester. The first after about 12-14 hours of lectures and the second on completion of the lecture program. These tests permit the student to pass the course. The first test in particular allows both the students and lecturer to identify any teaching/learning difficulties which can subsequently be corrected early in the course.