Chapter 11: Addition Reactions

Addition Reactions walks through key reactions such as hydrogenation (adding H₂ via syn addition), hydrohalogenation (HX additions governed by carbocation stability), and radical anti-Markovnikov additions of HBr (in the presence of peroxides). The mechanisms of acid-catalyzed hydration and hydroboration-oxidation are broken down to show how Markovnikov and anti-Markovnikov hydration of alkenes occur, respectively, each with distinct stereochemical outcomes. Students also learn halogenation reactions (Br₂ additions via bromonium ions), halohydrin formation (Br and OH addition), and both anti- and syn-dihydroxylation (using MCPBA/H₃O⁺ or OsO₄/H₂O₂, respectively). The chapter finishes with ozonolysis, an oxidative cleavage that splits alkenes into carbonyl compounds. A major emphasis is placed on using reaction mechanisms to predict regio- and stereochemical outcomes, avoid memorization, and apply reactions in multi-step synthesis strategies, including shifting leaving groups or π bonds, and introducing functionality via radical halogenation. Mastery of these reactions equips students to confidently approach complex transformation problems in organic chemistry.