Functionalization of saturated hydrocarbons by aprotic superacids 4. Ionic bromination of ethane and other alkanes and cycloalkanes with molecular bromine in the presence of systems based on polyhalomethanes and AlBr3 under mild conditions

Abstract

Aprotic organic superacids CBr4 · 2AlBr3, CBr4 · AIBr3, CHBr3 · 2AlBr3, CCl4 · 2AlBr3, and C6F5CF3 -2AlBr3 efficiently catalyze the bromination of alkanes and cycloalkanes with Br2. Ethane is selectively brominated at 55–65 °C to give mostly 1,2-dibromoethane (stoichiometric reaction). Propane, butane, cyclopentane, cyclohexane, and methylcyclopentane react with Br2 at -40 to -20 °C with good selectivity affording monobromides in high yields (catalytic reactions).