Chapter 11: Addition to Carbon–Carbon Multiple Bonds

The treatment begins with electrophilic addition to alkenes, establishing how regioselectivity operates through Markovnikov and anti-Markovnikov pathways, alongside the stereochemical consequences of reactions including halogenation, hydrohalogenation, and hydration processes. The chapter distinguishes between concerted mechanisms and stepwise pathways involving carbocation intermediates, exploring how reaction conditions and catalyst choice direct selectivity outcomes. Emphasis is placed on understanding carbocation rearrangement phenomena through hydride and alkyl shifts, which can both complicate and redirect synthetic pathways. The formation of cyclic intermediates such as bromonium ions is detailed as a means to achieve stereochemical control in halogenation. Nucleophilic addition processes to electron-deficient alkenes receive substantial attention, particularly within conjugated systems where resonance effects modulate reactivity patterns. Radical-mediated additions and hydrofunctionalization strategies are presented as complementary approaches to traditional electrophilic mechanisms. The chapter extends coverage to alkyne reactivity, addressing partial reduction techniques via Lindlar catalysis and dissolving-metal methods that provide access to cis and trans alkene products with controlled stereochemistry. Complex cases involving allenes and strained ring systems demonstrate how structural features influence addition pathways and selectivity. Throughout, the interplay between thermodynamic and kinetic control, reaction mechanism, and synthetic utility provides students with comprehensive insight into harnessing multiple bond reactivity for constructing complex molecules.