4 H SH t Br-Br CHa H CH CH CHA CHi H H H CH3 I3C KMno OH OH HCV KMno CH3 CHS HH,O H OH OH H:G/H HCH3 H,O H3G/H KMnO OHOH *反应结果为一对对映体,组成外消旋体。 CH H-—Br t Br-Bi Hs 所得产物为内消旋体,无旋光性 H4． ① ② Br Br Br Br  + H H  H CH3 + H Br Br Br - Br CH3 CH3 H CH3 CH3 C C H H CH3 H CH3 CH3 C CH3 H H H H CH3 CH3 CH3 CH3 Br Br Br Br ① ② 5． ① ② Br Br Br Br  + H H  H CH3 + H Br Br Br - Br CH3 CH3 H CH3 CH3 C C H H CH3 H CH3 CH3 C CH3 H H H H CH3 CH3 CH3 CH3 Br Br Br Br ① ② 6． H2O O OH CH3 C KMnO4 H CH3 3C H H H C H H H H 3C CH3 CH3 O O Mn O H H H 3C CH3 OH OH OH 7． H2O O CH3 C KMnO4 CH3 H3C HO H H H C H H H CH3 CH3 CH3 CH3 O O Mn O H H CH3 OH OH OH H2O O CH3 C KMnO4 CH3 H3C HO H H H C H H H H 3C CH3 CH3 O O Mn O H H H 3C CH3 OH OH OH *反应结果为一对对映体，组成外消旋体。 8． C2H5 ① ② Br Br Br Br  + H H  H + H Br Br Br - Br H C C H H H CH3 C H H H H Br Br Br Br ① ② C2H5 C2H5 C2H5 C2H5 C2H5 C2H5 所得产物为内消旋体，无旋光性。 C2H5 C2H5 C2H5 C2H5 C2H5