An organic reaction transforms organic compounds by changing their bonds, charge, or stereochemistry. Useful families include substitution reactions, addition reactions, elimination reactions, and rearrangements.
A reaction mechanism follows electron movement and intermediates rather than only comparing starting and final formulas. For instance, replacing a leaving group by a nucleophile can occur by a concerted pathway or through a carbocation intermediate; the two pathways predict different rate laws and stereochemical outcomes. Reaction classes organize transformations, while mechanisms explain how particular conditions produce them.
New to topics? Read the docs here!