12.6 Alkadienes and polyunsaturated hydrocarbons (二烯烃和多不饱和烃) The multiple bonds of polyunsaturated compounds are classified as being cumulated, conjugated, or isolated 1. Cumulated dienes(累积二烯烃) 123 2345 H2C=C=cH2H2C=c=cH—cH3Hc—HC=c=cH-cH3 2.3-pentadiene 1. 2-Propadiene 1.2-butadiene 1,2-丙二烯1,2-丁二烯 2,3-戊二烯12.6 Alkadienes and polyunsaturated hydrocarbons (二烯烃和多不饱和烃） The multiple bonds of polyunsaturated compounds are classified as being cumulated, conjugated, or isolated. 1. Cumulated dienes (累积二烯烃） H2 C C CH2 1,2-Propadiene 1， 2-丙 二 烯 1 2 3 H2C C CH 1,2-butadiene 1， 2-丁 二 烯 CH3 1 2 3 4 HC C CH 2,3-pentadiene 2,3-戊 二 烯 CH3 1 2 3 4 5 H3C