This Demonstration shows a common class of reactions of benzene: electrophilic substitutions. In the first substitution, phase I, displaced electrons on the aromatic ring attract an electrophilic species , positively charged in almost all the cases. A carbocation is formed, stabilized by resonance contributions with increased positive charge in the ortho and para positions. In the first substitution phase II, protons, , are removed from the ring, thus restoring charge neutrality and aromaticity. Benzene is a planar molecule, with all of its bonds represented in black. The other bonds in the carbocation above and below the plane are colored in blue and red.