11.1: Structure and Physical Properties Alkynes are unsaturated hydrocarbons with carbon-carbon triple bonds. As hydrocarbons, they are non-polar similar to alkanes. However, the two pi bonds create chemical reactivity similar to alkenes. 11.2: 10.2 Synthesis of Alkynes - Elimination Reactions of Dihalides Alkynes can be a useful functional group to synthesize due to some of their antibacterial, antiparasitic, and antifungal properties. One simple method for alkyne synthesis is by double elimination from a dihaloalkane. 11.3: Reactions of Alkynes - Addition of HX and X₂ The two pi bonds of alkynes allow them to undergo electrophilic addition reactions (EARs) similar to alkenes. 11.4: Hydration of Alkynes for Markovnikov Products Hydration of alkynes can produce the Markovnikov products with a slight modification to the oxymercuration-demercuration reaction system for alkenes. Enol-keto tautomerism is explained and applied to the alkyne hydration mechanism. 11.5: Hydration of Alkynes for Anti-Markovnikov Products The hydroboration-oxidation reaction we learned for alkenes is modified slightly for reactions with alkynes to produce anti-Markovniknov products. This mechanism also includes enol-keto tautomerism. 11.6: 10.6 Reduction of Alkynes Alkynes can be fully reduced to alkanes or specialty reagents can be used to stop the reduction at the alkene. The specialty reagents are distinguished by their reaction mechanism stereochemistry to produce cis or trans alkenes. 11.7: Oxidation of Alkynes Similar to alkenes, alkynes can be oxidized using gentle or strong reaction conditions to produce different products. 11.8: Acidity of Terminal Alkynes and Acetylide Ions Terminal alkynes are much more acidic than most other hydrocarbons. Removal of the alkyne proton is possible to form a strong nucleophile, the acetylide anion, RC=C:-, which can be used in subsequent reactions, particularly SN1 and SN2. 11.9: Synthesis of Larger Alkynes from Acetylides The alkylation of acetylide ions is important in organic synthesis because it is a reaction in which a new carbon-carbon bond is formed building larger organic molecules. 11.10: An Introduction to Multiple Step Synthesis Integrating the different reactions from the first 10 chapters of this text into multiple step synthetic pathways is an important skill in mastering organic chemistry. 11.11: Additional Exercises This section has additional exercises for the key learning objectives of this chapter. 11.12: Solutions to Additional Exercises This section has the solutions to the additional exercises from the previous section.