sulfonic acid

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Related to sulfonic acid: Sulfinic acid

sulfonic acid

(səlfŏn`ĭk), organic compound containing the functional groupfunctional group,
in organic chemistry, group of atoms within a molecule that is responsible for certain properties of the molecule and reactions in which it takes part. Organic compounds are frequently classified according to the functional group or groups they contain.
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 RSO2OH, which consists of a sulfur atom, S, bonded to a carbon atom that may be part of a large aliphatic or aromatic hydrocarbonhydrocarbon
, any organic compound composed solely of the elements hydrogen and carbon. The hydrocarbons differ both in the total number of carbon and hydrogen atoms in their molecules and in the proportion of hydrogen to carbon.
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, R, and also bonded to three oxygen atoms, O, one of which has a hydrogen atom, H, attached to it. The hydrogen atom makes the compound acidic, much as the hydrogen of a carboxylic acid (see carboxyl groupcarboxyl group
, in chemistry, functional group that consists of a carbon atom joined to an oxygen atom by a double bond and to a hydroxyl group, OH, by a single bond. Carboxylic acids are compounds whose molecules contain a carboxyl group that is joined to a hydrogen atom, an
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) makes it acidic (see acids and basesacids and bases,
two related classes of chemicals; the members of each class have a number of common properties when dissolved in a solvent, usually water. Properties
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). However, while carboxylic acids are weak (with dissociation constants of about 10−5), sulfonic acids are considered strong acids (with dissociation constants of about 10−2). Because sulfonic acids are so acidic, they generally exist as their saltssalt,
chemical compound (other than water) formed by a chemical reaction between an acid and a base (see acids and bases). Characteristics and Classification of Salts

The most familiar salt is sodium chloride, the principal component of common table salt.
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 and thus tend to be quite soluble in water. Sulfonic acid groups are often introduced into organic molecules such as dyes to stabilize them for use in aqueous dye baths. Sulfonic acid groups also improve the washfastness of wool and silk dyes by enabling the dye to bind more tightly to the fabric. The most important use of sulfonic acid salts (sulfonates) is in the detergent industry. Sodium salts of long-chain aliphatic or aromatic sulfonic acids are used as detergents. Unlike ordinary soapssoap,
a cleansing agent. It cleanses by lowering the surface tension of water, by emulsifying grease, and by absorbing dirt into the foam.

Ancient peoples are believed to have employed wood ashes and water for washing and to have relieved the resulting irritation with
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, which contain carboxylic acid salts, soaps containing sulfonates do not form a scum in hard water because the calcium and magnesium ions present in the hard water do not form insoluble precipitates with sulfonates as they do with carboxylates. Some sulfonic acid derivatives, e.g., the sulfa drugs, are important as antibiotics.

Sulfonic Acid


any of several acids of the general formula RSO3H, where R is an aliphatic or aromatic hydrocarbon radical. Sulfonic acids are usually hygroscopic, crystalline substances that dissolve readily in water. Their acidity is close to that of mineral acids.

Aromatic sulfonic acids are obtained by sulfonation of aromatic hydrocarbons and their derivatives. Aliphatic sulfonic acids are prepared by sulfochlorination of hydrocarbons or by replacement of the halogen with the sulfonic acid group, —SO3H (see).

Under the action of PC15, sulfonic acids are converted to sulfo-nyl chlorides, RSO2C1. Reduction of sulfonic acids produces sulfinic acids, RSO2H, and mercaptans, RSH. The SÓ3H group in the aromatic ring is easily replaced by H, OH, OR, H2N, R2N, and other groups under the action of nucleophilic reagents.

Aromatic sulfonic acids are important intermediates in industrial organic synthesis, such as the production of phenols. They are used in the production of azo dyes, sulfa drugs, ion-exchange resins, and additives for electroplating baths. The basic and quaternary ammonium salts of aliphatic sulfonic acids, called sulfonates, are surfactants and are used as components of detergents.

In inorganic chemistry, the term “sulfonic acid” is sometimes used in reference to thio acids.


sulfonic acid

[¦səl¦fän·ik ′as·əd]
(organic chemistry)
A compound with the radical ‒SO2OH, derived by the sulfuric acid replacement of a hydrogen atom; for example, conversion of benzene, C6H6, to the water-soluble benzenesulfonic acid, C6H5SO3H, by treatment with sulfuric acid; used to make dyes and drugs.
References in periodicals archive ?
We presented the synthesis, characterization and dyeing assessment of three novel acid dyes based on substituted aryl amines as diazo component and aminohydroxy-naphthalene sulfonic acid as coupling components.
This is thought to be due to the unavailability of the electron pairs of the NH groups, which become progressively attached to the increased population of the electron-withdrawing sulfonic acid groups at higher CSA concentrations.
Note: Et-PFOSA-AcOH, N-ethyl-perfluorooctane sulfonamido acetic acid; Me-PFOSA-AcOH, N-methyl-perfluorooctane sulfonamido acetic acid; PFHxS, perfluorohexane sulfonic acid; PFNA, perfluorononanoic acid; PFOA, perfluorooctanoic acid; PFOS, perfluorooctanesulfonic acid.
Sulfonic acid groups prevent proton conduction from interacting with imidazole groups.
1-naphthalene sulfonic acid, sodium salt###2.0%###98.44 +- 0.11 a###pass
Figure 1 presents the FT-IR spectra of nano-[gamma]-[Al.sub.2][O.sub.3] and sulfonic acid functionalized nano-[gamma]-[Al.sub.2][O.sub.3].
Liquefaction of cellulose in the presence of phenol using p-toluene sulfonic acid as a catalyst.
In the IR spectrum of ATBS, the band corresponding to the OH group in sulfonic acid is found at 2946 [cm.sup.-1].
Perfluorooctane sulfonic acid (PFOS) appears in a wide range of products from electronics components to fire-fighting foam, and trade in it amounts to billions of dollars a year.
Hydroxybenzyl alcohol groups as well as sulfonic acid groups on the carbon alpha to the aromatic rings of the phenylpropane units of the random polymer react with the aromatic nuclei of other phenylpropane units in the presence of the strong mineral acids.
Substance Indicating color [] (V) 2,3'-diphenylamine blue-violet +1.12 dicarboxylic acid diphenylamine sulfonic acid red-violet +0.85 diphenylamine violet +0.76 iodine:starch Blue-black +0.54 luminol chemiluminescent
A detailed chemical analysis of the affected tablets showed they contain higher than normal levels of methane sulfonic acid ethyl ester.