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been replaced by a carbon group or a compound where a hydrogen atom has been
replaced by treatment with sulfuric acid; for example, benzene is converted to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 intermediates for a number of biologically active compounds and
pharmaceutical candidates such as sulfa drugs.
Cresols are
methyl substituted phenols at relative to the hydroxyl group, ortho-, meta-, and
para-cresol. There are three structural isomers. The names of the three
compounds indicate which of the hydrogens on the benzene ring portion of the
molecule have been replaced. They are obtained from coal tar or petroleum as
by-products in the fractional distillation and in coal gasification. They are
also formed as by-products during the combustion of wood. The various isomers
can be manufactured by the methylation of phenol, toluene sulfonation and
alkaline hydrolysis, or the hydrolysis of 2-isopropyltoluene or alkaline
chlorotoluene. Because the boiling points of these three compounds are nearly
the same, a separation of a mixture of the three into its pure components is
impractical. They are highly flammable and soluble in water, ethanol, ether,
acetone and alkali hydroxides. The mixture of cresols obtained from coal tar is
called cresylic acid, an important technical product used as a disinfectant and
in the manufacture of resins and tricresyl phosphate. Cresylic acid also refs to
the mixture of phenols containing varying amounts of xylenols, cresols, and
other high-boiling fractions, but not more than 5 percent phenol. Commercial
cresols are prepared in a wide range of grades and purities to meet the user's
requirements. It is a liquid from clear to brown and is toxic to animals
including human. It is corrosive and is a more powerful disinfectant and
antiseptic than phenol. The primary use is for sterilizing as disinfectants and
deodorizers, and pesticides. Its solution is used as household cleaners as a
disinfectant. Creosote products are
mixtures of many aromatic hydrocarbons including phenols and cresols. Creosote
obtained from coal tar is poisonous and provides protection against fungi,
shipworms, termites, and psoriasis. It is used chiefly as a wood preservative,
e.g., in wooden poles, railroad ties, and timber. They are also used as animal
and bird repellents. Animals may suffer skin irritation or ulceration from
creosote treated wood. Coal tar creosote and its derivatives are the most widely
used wood preservatives. Wood tar creosote is a mixture of chiefly guaiacol,
creosols and other phenolic compounds obtained from wood tar (mainly beech) by
distillation between 203 and 220 C. It is insoluble in water, soluble in
methanol, acetone. It is used as an external antiseptic, expectorant, gastric
sedative, deodorant, and as an antiseptic parasiticide veterinary use in the
form of creosote carbonate. It is used in the synthesis of pharmaceuticals and
vanillin. Each cresols are used as
solvents or disinfectants and as useful as raw materials for various chemical
products including;
- Antiseptics,
disinfectants
- Fragrances,
deodorizing, odor-enhancer
- Resins
(phenol-formaldehyde, phenolic, and epoxy) and their additives
- Phosphate
esters (plasticizers)
- Herbicides
and pharmaceuticals
- Rubber and
plastic antioxidants
- Dyes and
pigments
- Household
cleaners and automotive degreasers
- Solvent and
paints
- Lubricating
oils, gasoline additives
- Adhesives
- Fiber and
wood preservatives
- UV- absorbers and
photographic chemicals
- Ore
flotation agents
Cresols
undergo electrophilic substitution reactions such as chlorination, bromination,
sulfonation and nitration at the vacant position. They also undergo condensation
reactions with aldehydes, ketones or dienes. O-cresol is a starting material for
the synthesis of herbicides such as 4,6-dinitro-o-cresol (DNOC) and
2-methyl-4-chlorophenoxyacetic acid (MCPA). Meta-cresol is used in the
manufacture of explosives. Meta and para-cresol are used in phenol-formaldehyde
resins and are converted to tricresyl phosphate used as a plasticizer and
gasoline additive and antioxidants such as di-tert-butylcresols (BHT). Ortho-
and para-cresols are used in the production of lubricating oils and motor
fuels.
Cresol sulfonic acids
are used in the manufacturing disinfectants
and friction dusts.
- o-Cresol sulfonic acid (CAS #: 52277-26-6)
- m-Cresol sulfonic acid (CAS #:
50851-56-4)
- p-Cresol sulfonic acid (CAS #: 74985-84-5)
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