Annulenes All cyclic conjugated hydrocarbons were proposed to be aromatic. However,cyclobutadiene is so reactive that it dimerizes before it can be isolated. Cyclooctatetraene adds Br2 readily to the double bonds. Molecular orbitals can explain aromaticity. Chapter 16 10 Chapter 16 10 Annulenes • All cyclic conjugated hydrocarbons were proposed to be aromatic. • However, cyclobutadiene is so reactive that it dimerizes before it can be isolated. • Cyclooctatetraene adds Br2 readily to the double bonds. • Molecular orbitals can explain aromaticity