In
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...
, the desulfonation reaction is the hydrolysis of
sulfonic acid
In organic chemistry, sulfonic acid (or sulphonic acid) refers to a member of the class of organosulfur compounds with the general formula , where R is an organic alkyl or aryl group and the group a sulfonyl hydroxide. As a substituent, it is kn ...
s:
:RC
6H
4SO
3H + H
2O → RC
6H
5 + H
2SO
4
The reaction applied to aryl and naphthylsulfonic acids. It is the reverse of
sulfonation 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. Aryl sulfonic acids are used as detergents, dye, and drugs.
Stoichiometry a ...
.
[Otto Lindner, Lars Rodefeld "Benzenesulfonic Acids and Their Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. ] The temperature of desulfonation correlates with the ease of the sulfonation.
Applications in synthesis
This reactivity is exploited in the regiospecific preparation of many di- and tri-substituted aromatic compounds.
2-Chlorotoluene Chlorotoluene is a group of three isomeric chemical compounds. They (''ortho''-chlorotoluene, ''meta''-chlorotoluene, and ''para''-chlorotoluene) consist of a disubstituted benzene ring with one chlorine atom and one methyl group.
Properties
Th ...
for example can be prepared by chlorination of
p-toluenesulfonic acid
''p''-Toluenesulfonic acid (PTSA or ''p''TsOH) or tosylic acid (TsOH) is an organic compound with the formula CH3 C6H4 SO3H. It is a white extremely hygroscopic solid that is soluble in water, alcohols, and other polar organic solvents. The CH3C ...
, followed by hydrolysis. The method is also useful for the preparation of 2,6-
dinitroaniline Dinitroanilines are a class of chemical compounds with the chemical formula C6H5N3O4. They are derived from both aniline and dinitrobenzenes. There are six isomers: 2,3-dinitroaniline, 2,4-dinitroaniline, 2,5-dinitroaniline, 2,6-dinitroaniline, 3, ...
and 2-bromophenol via phenol-2,4-disulfonic acid.
[{{cite journal, title=o-Bromophenol, authors=Ralph C. Huston, Murel M. Ballard, journal=Org. Synth., year=1934, volume=14, page=14, doi=10.15227/orgsyn.014.0014]
References
Organic reactions
Substitution reactions