Mechanism Problems (Dotted Line Convention)
In these problems you will be asked to draw chemically reasonable curved (curly) arrows to account for the transformations. These problems use the 'dotted line' convention, in which the formation of new bonds must be indicated by drawing dotted lines between the atoms. (Problems using the more conventional formalism that does not require drawing dotted lines are also available.)
The problems do not require you to predict the structures of possible intermediates in multi-step reactions; all intermediates are shown.
The mechanism of a reaction is the sequence of steps in the reaction, including details of the bonds are formed and/or broken in each step. Understanding mechanisms is key to understanding the reactions of organic compounds, and is essential to being able to use those reactions to make useful compounds.
Curved (curly) arrows, aka 'elecron pushers', are used to represent the movement of pairs of electrons in the bond forming and breaking events in the mechanism.
Note that 'correct' curved arrow mechanisms are provisional, further research may show that some of them are wrong. Moreover, they only show reasonable pathways of electron flow, and do not include any information about other aspects such as the relative energies of the species involved.
It is best to think of curved arrow 'mechanisms' as greatly simplified models that are nevertheless very useful because they help chemists to understand key aspects of the reactions.
On This Page:
On this page you will be given the starting materials, intermediates and products for common organic reactions and can practise drawing the curly (curved) arrow mechanisms for the transformations.
Only the most common mechanisms are inlcuded, and they are organised by type (e.g. 'acyl substitution') in the way that most students will encounter them.
Learning Objectives:
- Draw curved arrow mechanisms for common reactions.
- Understand the reactivity of organic compounds.
