Annulenes All cyclic conjugated hydrocarbons were proposed to be aromatic. However,cyclobutadiene is so reactive that it dimerizes before it can be isolated. And cyclooctatetraene adds Br2 readily. Pea:son Prentice Hall, Look at MO's to explain aromaticity. => Chapter 16 7Chapter 16 7 Annulenes • All cyclic conjugated hydrocarbons were proposed to be aromatic. • However, cyclobutadiene is so reactive that it dimerizes before it can be isolated. • And cyclooctatetraene adds Br2 readily. • Look at MO’s to explain aromaticity. =>