Monoene and dienes only a saturation, and dienes can be divided into three types: cumulative olefins, and conjugated dienes and isolation of the diolefins, isolate the alkadiene nearly the same with single olefin nature, and the properties of distinguishing is cumulative and conjugated dienes cumulative alkadiene nature too lively, generally difficult to exist, such as allene conjugated dienes with two double bonds in the conjugate position, formed from the domain keys, electron cloud become average, cause the special nature, such as 1, 2, 1, 3 - butadiene bonus and 1, 4 addition