sulfonic acid
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sulfonic acid
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.
B. L. DIATKIN