What is the product of the following reaction: 3. Without sulfuric acid the reaction would not occur. The sulfur in sulfur trioxide is electrophilic because the oxygens pull electrons away from it because oxygen is very electronegative. The sulfur in sulfur trioxide is electrophilic because the oxygens pull electrons away from it because oxygen is very electronegative. Because sulfonation is a reversible reaction, it can also be used in further substitution reactions in the form of a directing blocking group because it can be easily removed. It is important to note that the chemical formula of the sulfonic group is -SO 3 H. The reaction is reversed by adding hot aqueous acid to benzenesulfonic acid to produce benzene. (For questions 1 and 2 see Electrophilic Aromatic Substitution for hints). Sulfuric acid is needed in order for a good electrophile to form. Organic Chemistry : Structure and Function. What is the product of the following reaction: 9. The reversibility of the sulfonation reaction creates an opportunity to prepare deuterated benzene. Sulfuric acid protonates nitric acid to form the nitronium ion (water molecule is lost). Sulfonation of benzene The sulfonic group blocks the carbon from being attacked by other substituents and after the reaction is completed it can be removed by reverse sulfonation. Sulfur trioxide readily reacts with water to produce sulfuric acid and heat. Contents. . Sulfuric acid is needed in order for a good electrophile to form. Nitration: Methods and Mechanisms. The formation of the electrophile. Warm benzene under reflux at 40°C with fuming sulphuric acid for 20 to 30 minutes. Sulfonation of Benzene Sulfonation is a reversible reaction that produces benzenesulfonic acid by adding sulfur trioxide and fuming sulfuric acid. There are two equivalent ways of sulphonating benzene: Heat benzene under reflux with concentrated sulphuric acid for several hours. A subsequent proton transfer occurs to produce benzenesulfonic acid. 4 Related Records Expand this section. 4. American Chemical Society. 6 Information Sources. Laali, Kenneth K., and Volkar J. Gettwert. Register now! What is/are the required reagent(s)for the following reaction: 8. Free LibreFest conference on November 4-6! Sauls, Thomas W., Walter H. Rueggeberg, and Samuel L. Norwood. Sulfur trioxide readily reacts with water to produce sulfuric acid and heat. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. Register now! Concentrated sulphuric acid contains traces of SO3 due to slight dissociation of the acid. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Why is it important that the nitration of benzene by nitric acid occurs in sulfuric acid? The first step in the nitration of benzene is to activate HNO3with sulfuric acid to produce a stronger electrophile, the nitronium ion. Sulfonation is a reversible reaction that produces benzenesulfonic acid by adding sulfur trioxide and fuming sulfuric acid. Nitration and sulfonation of benzene are two examples of electrophilic aromatic substitution. For other problems involving Electrophilic Aromatic Substitution and similar reactions see: 3. It is important to note that the chemical formula of the sulfonic group is -SO3H. Write a detailed mechanism for the sulfonation of benzene, including all resonance forms. “On the Mechanism of Sulfonation of the Aromatic Nucleus and Sulfone Formation.” The Journal of Organic Chemistry 66 (1955): 455-465. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. If you want this mechanism explained to you in detail, there is a link at the bottom of the page. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. The nitronium ion (NO2+) and sulfur trioxide (SO3) are the electrophiles and individually react with benzene to give nitrobenzene and benzenesulfonic acid respectively. Sulfur trioxide readily reacts with water to produce sulfuric acid and heat. The second stage of the reaction involves a transfer of the hydrogen from the ring to the negative oxygen. Benzenesulfonic acids are also used in the synthesis of detergents, dyes, and sulfa drugs. Free LibreFest conference on November 4-6! Have questions or comments? Talk me through this mechanism . The benzene reacts with the sulfur of sulfur trixoxide to form the sigma complex. 3 Chemical and Physical Properties Expand this section. Because the nitronium ion is a good electrophile, it is attacked by benzene to produce Nitrobenzene. Fuming sulphuric acid, H2S2O7, can be thought of as a solution of SO3 in sulphuric acid - and so is a much richer source of the SO3. The benzene attacks the sulfur (and subsequent proton transfers occur) to produce benzenesulfonic acid. 1. . 5th ed. 1 Structures Expand this section. Isotopically labeled reagents can be useful in determining reaction mechanisms since the C-D bond is stronger than the C-H bond. Further Applications of Nitration and Sulfonation American Chemical Society. “Electrophilic Nitration of Aromatics in Ionic Liquid Solvents.” The Journal of Organic Chemistry 66 (Dec. 2000): 35-40. Sulfonation of benzene is a reversible reaction. Dr. Dietmar Kennepohl FCIC (Professor of Chemistry, Athabasca University), Prof. Steven Farmer (Sonoma State University), William Reusch, Professor Emeritus (Michigan State U. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. Draw an energy diagram for the nitration of benzene. -30℃; b.p.760 156℃), it is used as a solvent, particularly for large-scale crystallisations, and for the introduction of phenyl groups in organic synthesis. To produce benzenesulfonic acid from benzene, fuming sulfuric acid and sulfur trioxide are added. Create: 2012-11-30. Help! To produce benzenesulfonic acid from benzene, fuming sulfuric acid and sulfur trioxide are added. Modifying the Influence of Strong Activating Groups, Further Applications of Nitration and Sulfonation, http://en.wikipedia.org/wiki/Aromatic_sulfonation, http://www.youtube.com/watch?v=s1qJ1...eature=related, http://www.chemtube3d.com/Electrophi...20benzene.html, http://www.youtube.com/watch?v=i7ucl...eature=related, Activating and Deactivating Benzene Rings, Electrophilic Attack on Disubstituted Benzenes. The source of the nitronium ion is through the protonation of nitric acid by sulfuric acid, which causes the loss of a water molecule and formation of a nitronium ion. 5. The products of aromatic nitrations are very important intermediates in industrial chemistry. . Fuming sulfuric acid, also refered to as oleum, is a concentrated solution of dissolved sulfur trioxide in sulfuric acid. Having nitrogen present in a ring is very useful because it can be used as a directing group as well as a masked amino group. Label the transition states. Sulfuric acid protonates nitric acid to form the nitronium ion (water molecule is lost). What is/are the required reagent(s)for the following reaction: 2. 1 Structures. Nitration is used to add nitrogen to a benzene ring, which can be used further in substitution reactions.