Unpredictable reaction
Scholl reaction and nanographene synthesis

Despite its outstanding performance, with examples of the formation of dozens of carbon-carbon bonds in a single step and with good yields, the Scholl reaction is not an ideal reaction. Its main shortcoming is its unpredictable reactivity. Its mechanism remains controversial, and it's not really possible to predict reaction times. On the other hand, many unexpected reactivities have also been reported, which is all the more troublesome when the synthesis of the flexible precursor required numerous synthetic steps and considerable effort.