Aromatic sulfonation

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In organic chemistry, aromatic sulfonation is an reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid (−SO2OH) group. Together with nitration and chlorination, aromatic sulfonation is a widely used electrophilic aromatic substitutions. [1] Aryl sulfonic acids are used as detergents, dye, and drugs.

Contents

Sulfonation reaction equation.svg

Stoichiometry and mechanism

Sulfur trioxide is the active ingredient in many sulfonation reactions. Sulfur-trioxide-2D-dimensions.svg
Sulfur trioxide is the active ingredient in many sulfonation reactions.

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: [2]

C6H6 + H2SO4 + SOCl2 → C6H5SO3H + SO2 + 2 HCl

Historically, mercurous sulfate has been used to catalyze the reaction. [3]

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 reaction 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 installed as directing groups to affect the position where a substitution may take place. [4]

Specialized sulfonation methods

Many method have been developed for introducing sulfonate groups aside from direction sulfonation.

A classic named reaction is the Piria reaction (Raffaele Piria, 1851) in which nitrobenzene is treated with a metal bisulfite forming an aminosulfonic acid as a result of combined nitro group reduction and sulfonation. [2] [5] [6]

The Piria reaction Piria reaction.png
The Piria reaction

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.

Synthesis of sulfanilic acid from aniline and sulfuric acid. Amino Sulfonic Acid Synthesis V.1.svg
Synthesis of sulfanilic acid from aniline and sulfuric acid.

Applications

Allura Red AC, a food coloring agent, is made by a multistep process that includes two sulfonations. Allura Red AC Structural Formula V1.svg
Allura Red AC, a food coloring agent, is made by a multistep process that includes two sulfonations.

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.

See also

Related Research Articles

<span class="mw-page-title-main">Aromatic compound</span> Compound containing rings with delocalized pi electrons

Aromatic compounds or arenes are organic compounds "with a chemistry typified by benzene" and "cyclically conjugated." The word "aromatic" originates from the past grouping of molecules based on odor, before their general chemical properties were understood. The current definition of aromatic compounds does not have any relation to their odor. Aromatic compounds are now defined as cyclic compounds satisfying Hückel's Rule. Aromatic compounds have the following general properties:

<span class="mw-page-title-main">Phenyl group</span> Cyclic chemical group (–C₆H₅)

In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula C6H5, and is often represented by the symbol Ph or Ø. The phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen, which may be replaced by some other element or compound to serve as a functional group. A phenyl group has six carbon atoms bonded together in a hexagonal planar ring, five of which are bonded to individual hydrogen atoms, with the remaining carbon bonded to a substituent. Phenyl groups are commonplace in organic chemistry. Although often depicted with alternating double and single bonds, the phenyl group is chemically aromatic and has equal bond lengths between carbon atoms in the ring.

<span class="mw-page-title-main">Naphthalene</span> Chemical compound

Naphthalene is an organic compound with formula C
10
H
8
. It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is the main ingredient of traditional mothballs.

The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an aromatic ring. Friedel–Crafts reactions are of two main types: alkylation reactions and acylation reactions. Both proceed by electrophilic aromatic substitution.

In organic chemistry, an aryl halide is an aromatic compound in which one or more hydrogen atoms, directly bonded to an aromatic ring are replaced by a halide. Haloarenes are different from haloalkanes because they exhibit many differences in methods of preparation and properties. The most important members are the aryl chlorides, but the class of compounds is so broad that there are many derivatives and applications.

<span class="mw-page-title-main">Anthraquinone</span> Yellow chemical compound: building block of many dyes

Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula C
14
H
8
O
2
. Several isomers exist but these terms usually refer to 9,10-anthraquinone wherein the keto groups are located on the central ring. It is used as a digester additive to wood pulp for papermaking. Many anthraquinone derivatives are generated by organisms or synthesised industrially for use as dyes, pharmaceuticals, and catalysts. Anthraquinone is a yellow, highly crystalline solid, poorly soluble in water but soluble in hot organic solvents. It is almost completely insoluble in ethanol near room temperature but 2.25 g will dissolve in 100 g of boiling ethanol. It is found in nature as the rare mineral hoelite.

<span class="mw-page-title-main">Nitration</span> Chemical reaction which adds a nitro (–NO₂) group onto a molecule

In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group into an organic compound. The term also is applied incorrectly to the different process of forming nitrate esters between alcohols and nitric acid. The difference between the resulting molecular structures of nitro compounds and nitrates is that the nitrogen atom in nitro compounds is directly bonded to a non-oxygen atom, whereas in nitrate esters, the nitrogen is bonded to an oxygen atom that in turn usually is bonded to a carbon atom.

<span class="mw-page-title-main">Sulfonic acid</span> Organic compounds with the structure R−S(=O)2−OH

In organic chemistry, sulfonic acid refers to a member of the class of organosulfur compounds with the general formula R−S(=O)2−OH, where R is an organic alkyl or aryl group and the S(=O)2(OH) group a sulfonyl hydroxide. As a substituent, it is known as a sulfo group. A sulfonic acid can be thought of as sulfuric acid with one hydroxyl group replaced by an organic substituent. The parent compound is the parent sulfonic acid, HS(=O)2(OH), a tautomer of sulfurous acid, S(=O)(OH)2. Salts or esters of sulfonic acids are called sulfonates.

In organic chemistry, an electrophilic aromatic halogenation is a type of electrophilic aromatic substitution. This organic reaction is typical of aromatic compounds and a very useful method for adding substituents to an aromatic system.

<span class="mw-page-title-main">Polystyrene sulfonate</span> Drug class

Polystyrene sulfonates are a group of medications used to treat high blood potassium. Effects generally take hours to days. They are also used to remove potassium, calcium, and sodium from solutions in technical applications.

<span class="mw-page-title-main">Diazonium compound</span> Group of organonitrogen compounds

Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group [R−N+≡N]X where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. The parent compound where R is hydrogen, is diazenylium.

<span class="mw-page-title-main">Triflic acid</span> Chemical compound

Triflic acid, the short name for trifluoromethanesulfonic acid, TFMS, TFSA, HOTf or TfOH, is a sulfonic acid with the chemical formula CF3SO3H. It is one of the strongest known acids. Triflic acid is mainly used in research as a catalyst for esterification. It is a hygroscopic, colorless, slightly viscous liquid and is soluble in polar solvents.

In chemistry, a sulfonyl halide consists of a sulfonyl group singly bonded to a halogen atom. They have the general formula RSO2X, where X is a halogen. The stability of sulfonyl halides decreases in the order fluorides > chlorides > bromides > iodides, all four types being well known. The sulfonyl chlorides and fluorides are of dominant importance in this series.

<span class="mw-page-title-main">Neophyl chloride</span> Chemical compound

Neophyl chloride, C6H5C(CH3)2CH2Cl, is a halogenated organic compound with unusual nucleophilic substitution properties. Neophyl chloride is used to form a versatile organolithium reagent, neophyl lithium, by reaction with lithium.

<span class="mw-page-title-main">Benzenesulfonic acid</span> Chemical compound

Benzenesulfonic acid (conjugate base benzenesulfonate) is an organosulfur compound with the formula C6H6O3S. It is the simplest aromatic sulfonic acid. It forms white deliquescent sheet crystals or a white waxy solid that is soluble in water and ethanol, slightly soluble in benzene and insoluble in nonpolar solvents like diethyl ether. It is often stored in the form of alkali metal salts. Its aqueous solution is strongly acidic.

<span class="mw-page-title-main">Anthraquinone dyes</span>

Anthraquinone dyes are an abundant group of dyes comprising a anthraquinone unit as the shared structural element. Anthraquinone itself is colourless, but red to blue dyes are obtained by introducing electron donor groups such as hydroxy or amino groups in the 1-, 4-, 5- or 8-position. Anthraquinone dyestuffs are structurally related to indigo dyestuffs and are classified together with these in the group of carbonyl dyes.

Electrophilic aromatic substitution (SEAr) is an organic reaction in which an atom that is attached to an aromatic system is replaced by an electrophile. Some of the most important electrophilic aromatic substitutions are aromatic nitration, aromatic halogenation, aromatic sulfonation, alkylation Friedel–Crafts reaction and acylation Friedel–Crafts reaction.

<span class="mw-page-title-main">Alkylbenzene</span> Family of organic compounds

An alkylbenzene is a chemical compound that contains a monocyclic aromatic ring attaching to one or more saturated hydrocarbon chains. Alkylbenzenes are derivatives of benzene, in which one or more hydrogen atoms are replaced by alkyl groups. The simplest member, toluene, has the hydrogen atom of the benzene ring replaced by a methyl group. The chemical formula of alkylbenzenes is CnH2n-6.

Perchlorylbenzene (C6H5ClO3, PhClO3, is an aromatic compound prepared by direct electrophilic perchlorylation of benzene using perchloryl fluoride and aluminum trichloride:

<span class="mw-page-title-main">Desulfonation reaction</span>

In organic chemistry, the desulfonation reaction is the hydrolysis of sulfonic acids:

References

  1. March, Jerry (1985). Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.). New York: Wiley. ISBN   9780471854722. OCLC   642506595..
  2. 1 2 3 Lindner, Otto; Rodefeld, Lars (2000). "Benzenesulfonic Acids and Their Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a03_507. ISBN   978-3-527-30385-4.
  3. Sabatier, Paul (1922). Catalysis in Organic Chemistry. Translated by Reid, E. Emmet. New York, NY: Van Nostrand. p. 2.
  4. T.W. Graham Solomons: Organic Chemistry, 11th Edition, Wiley, Hoboken, NJ, 2013, p. 676, ISBN   978-1-118-13357-6.
  5. 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.
  6. The Piria Reaction. I. The Overall Reaction W. H. Hunter, Murray M. Sprung J. Am. Chem. Soc., 1931, 53 (4), pp 1432–1443 doi : 10.1021/ja01355a037.
  7. U.S. patent 1,210,725
  8. Siegfried Hauptmann: Organische Chemie, 2nd Edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 511, ISBN   3-342-00280-8.