12-2 Preparing Alkyl Halides from Alkenes: Allylic Bromination Methods of preparing alkyl halides Reactions of HX and X2 with alkenes in electrophilic addition reactions The hydrogen halides HCI,HBr,and HI react with alkenes by a polar mechanism to give the product of Markovnikov addition Bromine and chlorine undergo anti addition through a halonium ion intermediate to give 1,2-dihalogenated products HX H CH3 CH3 H CH3 X=CIor Br X=Cl,Br,or I O Cengege Loaming Al Rights Reserved Methods of preparing alkyl halides ▪ Reactions of HX and X2 with alkenes in electrophilic addition reactions ▪ The hydrogen halides HCl, HBr, and HI react with alkenes by a polar mechanism to give the product of Markovnikov addition ▪ Bromine and chlorine undergo anti addition through a halonium ion intermediate to give 1,2-dihalogenated products 12-2 Preparing Alkyl Halides from Alkenes: Allylic Bromination