This chapter explores the diverse and crucial world of reactive
intermediates, which play pivotal roles in the mechanisms and outcomes of organic
reactions. Beginning with an overview of reaction intermediates, we establish their
importance as transient species that facilitate the transformation of reactants to
products.
Carbocations, positively charged species with significant implications for reactivity
and stability, are examined in detail, highlighting their formation, stabilization factors,
and roles in various organic reactions. Carbanions, their negatively charged
counterparts, are discussed with a focus on their nucleophilic nature, stabilization
mechanisms, and involvement in organic synthesis. After that, the chapter delves into
carbenes, neutral species with a divalent carbon atom, emphasizing their unique
reactivity and applications in cyclopropanation and insertion reactions. Free radicals,
species with unpaired electrons, are analyzed for their formation, stability, and
participation in radical reactions, which are crucial in polymerization and
halogenation processes.
The chapter continues with an examination of nitrenes, and nitrogen analogs of
carbenes, noting their reactivity and applications in aziridination and insertion
reactions. Arynes and benzynes, highly reactive intermediates derived from aromatic
compounds, are explored, focusing on their formation and role in nucleophilic
aromatic substitution reactions.
Enamines, intermediates formed from aldehydes or ketones and secondary amines,
are discussed in the context of their stability and utility in organic synthesis,
particularly in the Stork enamine reaction. The concept of formal charge is introduced
to aid in understanding the electronic structure and reactivity of intermediates,
providing a foundational tool for predicting the behavior of these species.
Through a comprehensive analysis of these reactive intermediates, this chapter equips
readers with the knowledge to understand and predict the behavior of complex organic
reactions, laying the groundwork for advanced studies and practical applications in
organic chemistry.
Keywords: Reaction intermediates; carbocations; carbanions; carbenes; free radicals; nitrenes; arynes; benzyne; enamines; formal charge.
