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Many other electrophilic reactions of benzene are conducted, although on a much smaller scale; they are valuable routes to key intermediates. The nitration of benzene is achieved via the action of the nitronium ion as the electrophile. The sulfonation with fuming sulfuric acid gives benzenesulfonic acid.
In the Tyrer sulfonation process (1917), [7] at some time of technological importance, benzene vapor is led through a vessel containing 90% sulfuric acid the temperature of which is increased from 100 to 180°C. Water and benzene are continuously removed and the benzene fed back to the vessel. In this way an 80% yield is obtained.
In electrophilic substitution in aromatic compounds, an atom appended to the aromatic ring, usually hydrogen, is replaced by an electrophile. The most important reactions of this type that take place are aromatic nitration, aromatic halogenation, aromatic sulfonation and acylation and alkylating Friedel-Crafts reactions. It further consists of ...
Diagram showing the ortho, meta and para positions relative to a substituent X on a benzene ring. Electron donating groups are typically divided into three levels of activating ability (The "extreme" category can be seen as "strong".)
Sulfonation of benzene involves the use of oleum, a mixture of sulfuric acid with sulfur trioxide. Sulfonated benzene derivatives are useful detergents. In nitration, benzene reacts with nitronium ions (NO 2 +), which is a strong electrophile produced by combining sulfuric and nitric acids. Nitrobenzene is the precursor to aniline.
A complexed electrophile can contribute to the stability of arenium ions. Salts of benzenium ion can be isolated when benzene is protonated by the carborane superacid H(CB 11 H(CH 3) 5 Br 6). [5] The benzenium salt is crystalline with thermal stability up to 150 °C.
Electrophiles are involved in electrophilic substitution reactions, particularly in electrophilic aromatic substitutions. In this example, the benzene ring's electron resonance structure is attacked by an electrophile E +. The resonating bond is broken and a carbocation resonating structure results.
In organosulfur chemistry, a sulfonyl group is either a functional group found primarily in sulfones, or a substituent obtained from a sulfonic acid by the removal of the hydroxyl group, similarly to acyl groups. [1]: 1470–1476