Curved Arrows and All that Jazz: Essential Tips on Writing Reaction Mechanism. A curved FULL arrow is used to represent the flow of a pair of electrons. A curved HALF arrow is used to represent the flow of one electron A Reaction Mechanism can be considered as the “language” of organic chemistry. Writing reaction mechanisms is essential if you need to describe how a particular reaction occurs. The use of curved arrows to depict the flow of electrons to and fro reactive sites and the careful accounting of the number of electrons that are involved from the beginning to the end of the reaction mechanism is an essential part of writing reaction mechanisms. Learning to write chemically sound reaction mechanisms takes practice and an appreciation of the nuances of the characteristic chemical reactivities of functional groups.

Electron-rich site: Nucleophile Electron-poor site: Electrophile Neutral Product Bond Formation Assume A is more electronegative than B. Charged Species are formed Heterolytic Bond Fission (Breaking) POLAR REACTIONS

FREE-RADICAL REACTION Bond Formation Free-Radicals Neutral Molecule Homolytic Bond Fission Free-Radicals are formedNeutral Molecule