CH3 CH3- CH3 CH3 Br Br 优势构象 CH3 CH3CH3 Br 消除构象 产物从区域选择性看，不符合扎依采夫规则。 Br CH3 CH3 CH3 CH3 Br H CH3CH3 Br CH3 H3C 优势构象 消除构象 产物从区域选择性看，不符合扎依采夫规则