Naphthalene is a
white, volatile aromatic hydrocarbon with characteristic odor; insoluble in
water, somewhat soluble in methanol/ethanol, soluble in organic solvents and
very soluble in ether, chloroform, or carbon disulfide. Commercially it is
available in molten form or in flaked form. It has the molecular structure of
two fused or condensed benzene rings sharing two adjacent carbon atoms;
C10H8. Naphthalene is obtained from coal tar which is
distilled in the temperature range of 170 - 230 C and is treated with a sodium
hydroxide solution to remove phenols. Naphthalene is obtained by the isolation
from pyrolysis residue oils, olefin fractions, and petroleum-derived fractions.
The distribution capacity is supposed to be about 60% coal-tar and 40%
petroleum-derived naphthalene in U.S.A. It is an important parent material to
produce numerous substitution products used in the manufacture of dyes,
insecticides, organic solvents and synthetic resins. Phthalic anhydride is
prepared by oxidizing naphthalene to be used in the manufacture of dyes, resins,
plasticizers, and insecticides. Naphthalene sulfonate surfactants and
dispersants, however, have increased their market share significantly and are
expected to drive whatever growth there is for naphthalene. Naphthalene is the
major raw material for Carbaryl, used as a general-purpose insecticide.
Naphthalene is also used for moth repellents, fungicides, lubricants,
explosives, wood preservatives, vermicides and hydronaphthalenes (tetralin,
decalin). Hydronaphthalenes are used for major raw material for dyes, resins,
plasticizers, and insecticides. They are also used in reactive and process
solvents, heat transfer fluid, dye carrier, fuel additives, lubricants, ore
flotation and oilfield chemicals. 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been replaced by a carbon group or a compound where a hydrogen atom has been
replaced by treatment with sulfuric acid; for example, benzene is converted to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. Short carbon chain metallic
sulfonate is used in electroplating which is a process for applying a metallic
coating on a metal surface by electrodeposition from a suitable electrolyte
solution for imparting corrosion resistance and direct production of printed
circuit boards without etching out of a piece of copper sheet.
Tobias acid
(
2-Amino-1-naphthalene
Sulfonic acid),
an important dye intermediate, is produced from naphthalene
by a combination of the unit processes of sulfonation,
nitration, reduction, and hydrolysis. Tobias
acid is used
in the manufacture of a large number of azo dyes and
pigments. |