Dienes or diolefins are hydrocarbons which contain two double bonds. Dienes are intermediate between alkenes and polyenes. Classes Dienes can be divided into three classes: Unconjugated dienes have the double bonds separated by two or more single bonds. Conjugated dienes have conjugated double bonds separated by one single bond. They're also the most stable. Cumulated dienes have the double bonds sharing a common atom as in a group of compounds called allenes. Heterodienes have one or more of… (More on Diene)