4.1.3异构 CH3 H 1.顺反异构 C-C H H CH (2E,4E)-2,4-己二烯或(E,E)-2,4-己二烯 H H 3 HRC C=C CH H3C H H 顺,顺-2,4-己二烯 顺,反-2,4-己二烯 (2Z,4Z)-2,4-己二烯 (2Z,4B)-2,4-己二烯