−CH2Cl \mathrm {-CH_2Cl}−CH2Cl
−CH2Br \mathrm {-CH_2Br}−CH2Br
−CHBrCl \mathrm {-CHBrCl}−CHBrCl
−CH2BrCl \mathrm {-CH_2BrCl}−CH2BrCl
