This new textbook is the successor to the volume "Side Reactions in Organic Synthesis - A Guide to Successful Synthesis Design" (2004), written by the same author. Whereas the predecessor mainly covered the limitations of aliphatic substitution reactions, this new volume focuses on the most important aromatic substitution reactions, both electrophilic and nucleophilic, such as amination reactions, halogenation reactions, Friedel-Crafts acylations, or transition metal-catalyzed arylation reactions. Each chapter not only describes the scope of a specific reaction type, but also reveals what cannot be achieved with this reaction, i.e. what type of side reactions are to be expected with certain starting materials or electrophiles/nucleophiles. With its unique approach, this is a must-have book for graduate students in organic chemistry and synthetic chemists both in academia and industry!