Aromatic sulfonation: Difference between revisions
m Added a sentence about sulfonate groups as protecting groups and directing groups. |
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[[File:Amino Sulfonic Acid Synthesis V.1.svg|thumb|360px|right|Synthesis of [[sulfanilic acid]] from aniline and sulfuric acid.<ref name=Hauptmann>Siegfried Hauptmann: ''Organische Chemie'', 2nd Edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 511, {{ISBN|3-342-00280-8}}.</ref>]] |
[[File:Amino Sulfonic Acid Synthesis V.1.svg|thumb|360px|right|Synthesis of [[sulfanilic acid]] from aniline and sulfuric acid.<ref name=Hauptmann>Siegfried Hauptmann: ''Organische Chemie'', 2nd Edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 511, {{ISBN|3-342-00280-8}}.</ref>]] |
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==Applications== |
==Applications== |
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Aromatic sulfonic acids are intermediates in the preparation of [[dye]]s and many pharmaceuticals. Sulfonation of [[aniline]]s lead to a large group of [[Sulfonamide (medicine)|sulfa drug]]s. |
Aromatic sulfonic acids are intermediates in the preparation of [[dye]]s and many pharmaceuticals. Sulfonation of [[aniline]]s lead to a large group of [[Sulfonamide (medicine)|sulfa drug]]s. |
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[[Image:Allura Red AC Structural Formula V1.png|thumb|180 px|left|[[Allura Red AC]], a food coloring agent, is made by a multistep process that includes two sulfonations.]] |
[[Image:Allura Red AC Structural Formula V1.png|thumb|180 px|left|[[Allura Red AC]], a food coloring agent, is made by a multistep process that includes two sulfonations.]] |
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Sulfonation of [[polystyrene]] is used to make [[sodium polystyrene sulfonate]], a common [[ion exchange resin]] for [[water softening]]. |
Sulfonation of [[polystyrene]] is used to make [[sodium polystyrene sulfonate]], a common [[ion exchange resin]] for [[water softening]]. |
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==Reactions of aryl sulfonic acids== |
==Reactions of aryl sulfonic acids== |
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As a [[functional group]], an aryl sulfonic acid exhibits two distinctive reactions: |
As a [[functional group]], an aryl sulfonic acid exhibits two distinctive reactions: |
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*When treated with strong base, benzenesulfonic acid derivatives converts to phenols (via the phenoxides). |
*When treated with strong base, benzenesulfonic acid derivatives converts to phenols (via the phenoxides). |
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:C<sub>6</sub>H<sub>5</sub>SO<sub>3</sub>H + 2 NaOH → C<sub>6</sub>H<sub>5</sub>ONa + NaHSO<sub>4</sub>H |
:C<sub>6</sub>H<sub>5</sub>SO<sub>3</sub>H + 2 NaOH → C<sub>6</sub>H<sub>5</sub>ONa + NaHSO<sub>4</sub>H |
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==See also== |
==See also== |
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*[[Electrophilic halogenation]] |
*[[Electrophilic halogenation]] |
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*[[Nitration]] |
*[[Nitration]] |
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*[[Perchlorylbenzene]] |
*[[Perchlorylbenzene]] |
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==References== |
==References== |
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{{Reflist}} |
{{Reflist}} |
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Revision as of 17:18, 28 December 2017
Aromatic sulfonation is an organic reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid functional group in an electrophilic aromatic substitution.[1] Aryl sulfonic acids are used as detergents, dye, and drugs.
Stoichiometry and mechanism
Typical conditions involve heating the aromatic compound with sulfuric acid:[2]
- C6H6 + H2SO4 → C6H5SO3H + H2O
Sulfur trioxide or its protonated derivative is the actual electrophile in this electrophilic aromatic substitution.
To drive the equilibrium, dehydrating agents such as thionyl chloride can be added.
- C6H6 + H2SO4 + SOCl2 → C6H5SO3H + SO2 + 2 HCl
Chlorosulfuric acid is also an effective agent:
- C6H6 + HSO3Cl → C6H5SO3H + HCl
In contrast to aromatic nitration and most other electrophilic aromatic substitutions this reaction is reversible. Sulfonation takes place in concentrated acidic conditions and desulfonation is the mode of action in a dilute hot aqueous acid. The reversibility is very useful in protecting the aromatic system because of this reversibility. Due to their electron withdrawing effects, sulfonate protecting groups can be used to prevent electrophilic aromatic substitution. They can also be intalled as directing groups to affect the position where a substitution may take place.[3]
Specialized sulfonation methods
Many method have been developed for introducing sulfonate groups aside from direction sulfonation.
Piria reaction
A classic named reaction is the Piria reaction (R. Piria, 1851) in which nitrobenzene is reacted with a metal bisulfite forming an aminosulfonic acid as a result of combined nitro group reduction and sulfonation.[4][5]
Tyre sulfonation process
In the Tyrer sulfonation process (1917),[6] 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 in a condenser and the benzene layer fed back to the vessel. In this way an 80% yield is obtained.
Applications
Aromatic sulfonic acids are intermediates in the preparation of dyes and many pharmaceuticals. Sulfonation of anilines lead to a large group of sulfa drugs.
Sulfonation of polystyrene is used to make sodium polystyrene sulfonate, a common ion exchange resin for water softening.
Reactions of aryl sulfonic acids
As a functional group, an aryl sulfonic acid exhibits two distinctive reactions:
- Desulfonation when heated in water near 200 ºC. The reaction, a hydrolysis, is the reverse of the sulfonation. The temperature of desulfonation correlates with the ease of the sulfonation:
- RC6H4SO3H + H2O → RC6H5 + H2SO4H
This reactivity is exploited in the regiospecific conversion of 2-chlorotoluene by chlorination of p-toluenesulfonic acid, followed by hydrolysis of the intermediate.
- When treated with strong base, benzenesulfonic acid derivatives converts to phenols (via the phenoxides).
- C6H5SO3H + 2 NaOH → C6H5ONa + NaHSO4H
See also
References
- ^ March, Jerry (1985), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 3rd edition, New York: Wiley, ISBN 9780471854722, OCLC 642506595.
- ^ Otto Lindner, Lars Rodefeld "Benzenesulfonic Acids and Their Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a03_507
- ^ T.W> Graham Solomons: Organic Chemistry, 11th Edition, Wiley, Hoboken, NJ, 2013, p. 676, ISBN 978-1-118-13357-6.
- ^ Piria, Raffaele (1851). "Über einige Produkte der Einwirkung des schwefligsäuren Ammoniaks auf Nitronaphtalin". Annalen der Chemie und Pharmacie. 78: 31–68. doi:10.1002/jlac.18510780103. ISSN 0075-4617.
- ^ THE PIRIA REACTION. I. THE OVER-ALL REACTION W. H. Hunter, Murray M. Sprung J. Am. Chem. Soc., 1931, 53 (4), pp 1432–1443 doi:10.1021/ja01355a037.
- ^ U.S. patent 1,210,725
- ^ Siegfried Hauptmann: Organische Chemie, 2nd Edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 511, ISBN 3-342-00280-8.