Sulfonic acid is a compound with general formula RSO2OH, where R is an aliphatic
or aromatic hydrocarbon. It is a derivative of sulfuric acid (HOSO2OH) where an
OH has been replaced by a carbon group or a compound where a hydrogen atom has
been replaced by treatment with sulfuric acid; for example, benzene is converted
to benzenesulfonic acid (water-soluble). Sulfonic acid has a sulfur atom bonded
to a carbon atom of a hydrocarbon and bonded also to three oxygen atoms, one of
which has been attached to a hydrogen atom. Sulfonic acid is acidic due to the
hydrogen atom, stronger than a carboxylic acid. Sulfonic acid is one of the most
important organo sulfur compounds in organic synthesis. Sulfonic acids are used
as catalysts in esterification, alkylation and condensation reactions.
Sulfonates are salts or esters of sulfonic acid. Sulfonic salts are soluble in
water. Sulfonic acid and its salts present in organic dyes provide useful
function of water solubility and or improve the washfastness of dyes due to
their capabiltity of binding more tightly to the fabric. They are widely used in
the detergent industry. Alkylbenzene sulfonic acid is the largest-volume
synthetic surfactant because of its relatively low cost, good performance, the
fact that it can be dried to a stable powder and the biodegradable environmental
friendliness. Sulfonate cleaners do not form an insoluble precipitates in hard
water. Sulfonic acid salts and esters are intermediates widely used in organic
synthesis and particularly phenolic compounds and cation exchange resins. They
are synthetic intermediate for a number of biologically active compounds and
pharmaceutical candidates such as sulfa drugs.
2-Amino-1-phenol-4-sulfonic acid is
used as intermediate for the synthesis of dyes, pigments
and other chemical compounds.
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