Required in chemistry laboratories that conduct electrophilic aromatic substitutions, the sulfonation flasks prepare and hold the highly volatile substance. By heating the corrosive material, attached atoms are replaced by substitutions that activate or deactivate to modify reaction rates. The glassware has the temperature and chemical resistance needed for the reversal test. With necks parallel or angled to fit apparatus configurations, the specially designed sulfonation flasks are available in a variety of opening quantities.