答案 (1)(CH3)3C—C(CH)3(2)(CH3)2CHCH(CH3)2 4写出异丁烷在光照下一溴化反应的机理。 答案 CH Br+H+cH→Hc+cH+HBr H Br·+H3C-CH3 H3C-+CH2 + HBr CH3 CH3 H3C--CHa+Br2 H3C--CH3 Br CH CH3 H3C--CH3 2一 H 5用纽曼投影式画出2,3一二甲基丁烷的几个极限构象式,并绘出C2C3键轴旋转的势能 变化示意图。 H3C 3C H3C CH3 H3c CH3 H3C HC CH3 H3C H3C HacX C CH3 H3C CH3答案： （1）(CH3)3C (2) (CH3)2CHCH(CH3)2 C(CH3)3 4.写出异丁烷在光照下一溴化反应的机理。 答案： H3C CH3 CH3 H Br2 hv 2 Br Br + H3C CH3 CH3 + HBr H3C CH3 CH3 H Br + H3C CH2 CH3 + HBr H H3C CH3 CH3 + Br2 H3C CH3 CH3 Br + Br H3C CH3 CH3 + Br2 H3C CH2Br CH3 H + Br 5.用纽曼投影式画出 2，3－二甲基丁烷的几个极限构象式，并绘出 C2-C3 键轴旋转的势能 变化示意图。 答案： CH3 H3C H H H3C CH3 H3C H CH3 H H3C CH3 H H3C CH3 H H3C CH3 H3C H3C H H H3C CH3 CH3 H CH3 H H3C CH3 H H3C CH3 H H3C CH3 H3C H CH3 H H3C CH3