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Jai Ganesh

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Coal tar

Coal tar

Gist

Coal tar is a thick, black, viscous liquid that's a byproduct of coal processing. It's used in medicine, chemical manufacturing, and road construction.

Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote.

Summary

Coal tar is a material that is derived from coal. The main constituent of this product is carbon and coal gas, and is extracted as a by-product during the production of coke which is a solid fuel. Coal is black in color and, like Natural bitumen or gilsonite , has properties such as viscosity and a naphthalene-like odor.

For this reason, coal tar can also be produced from diagonal bitumen, which has many applications in a variety of industries, including road construction, electrode production, and molded coal dust and glazing or pipe coating.

Formally, the coal diameter is a liquid and carbon is made from coal at 900 to 1200 ° C during the carbon manufacturing process.

Uses of coal tar

It is interesting to know that many of the compounds used in various industries utilize this material in their manufacture. Production of refined chemicals such as creosote and coal tar is one of these applications. It is also used in the medical industry and is used in drug manufacture related to diseases such as skin eczema, dandruff, psoriasis and more.

As it is known, medicines made from coal tar are used in skin treatments. The effect of these drugs is also on the degradative power of the horny part of the skin and the keratoplasty. These drugs can reduce the skin hyperplasia caused by proliferative disorders. They also have antifungal, antiseptic and antibacterial effects.

In short, they are carbonized when coal, peat and lignin or wood are at temperatures above 700 ° C. The result of this process is also the extraction of tar acids resulting from the reaction of phenolic compounds with caustic soda.

Also the main part of the tar are the alkaline elements of the distilled oils. These alkali elements remain after the removal of tar acids. Pyridine is one of these alkaline elements. A colorless liquid nitrogen with a pungent odor. It has medicinal value. Finally, with the extraction of peridine and other distillates, what remains is the material used in the aluminum industry.

Coal tar ingredients

This material is one of the derivatives of coal. Derivation of different materials from coal can be studied on the basis of temperature, type and conditions of coal decomposition between pressure and temperature. Typically coal types begin to lose moisture at 100 ° C; and up to 400 ° C, the process of decomposition begins. The output from coal decomposition includes both gaseous and oil materials, the bulk of which is coal tar.

Simply put, coal tar contains a variety of materials, including benzene, xylene, toluene, naphthalene, phthalate, anthracene and so on. The distillation method is used to separate these materials, and if the ambient temperature reaches over 900 ° C, the amount of it will be reduced. Finally, in the coal pyrolysis process, about 70 percent of this material is converted to coke and 5 percent to coal tar.

Details

Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote. It has both medical and industrial uses. Medicinally it is a topical medication applied to skin to treat psoriasis and seborrheic dermatitis (dandruff). It may be used in combination with ultraviolet light therapy. Industrially it is a railroad tie preservative and used in the surfacing of roads. Coal tar was listed as a known human carcinogen in the first Report on Carcinogens from the U.S. Federal Government, issued in 1980.

Coal tar was discovered circa 1665 and used for medical purposes as early as the 1800s. Circa 1850, the discovery that it could be used as the main raw material for the synthesis of dyes engendered an entire industry. It is on the World Health Organization's List of Essential Medicines. Coal tar is available as a generic medication and over the counter.

Side effects include skin irritation, sun sensitivity, allergic reactions, and skin discoloration. It is unclear if use during pregnancy is safe for the baby and use during breastfeeding is not typically recommended. The exact mechanism of action is unknown. It is a complex mixture of phenols, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic compounds. It demonstrates antifungal, anti-inflammatory, anti-itch, and antiparasitic properties.

Composition

Coal tar is produced through thermal destruction (pyrolysis) of coal. Its composition varies with the process and type of coal used – lignite, bituminous or anthracite.

Coal tar is a mixture of approximately 10,000 chemicals, of which only about 50% have been identified.[better source needed] Most of the chemical compounds are polycyclic aromatic hydrocarbon:

* polycyclic aromatic hydrocarbons (4-rings: chrysene, fluoranthene, pyrene, triphenylene, naphthacene, benzanthracene, 5-rings: picene, benzo pyrene, benzo pyrene, benzofluoranthenes, perylene, 6-rings: dibenzopyrenes, dibenzofluoranthenes, benzoperylenes, 7-rings: coronene)
* methylated and polymethylated derivatives, mono- and polyhydroxylated derivatives, and heterocyclic compounds.

Others: benzene, toluene, xylenes, cumenes, coumarone, indene, benzofuran, naphthalene and methyl-naphthalenes, acenaphthene, fluorene, phenol, cresols, pyridine, picolines, phenanthracene, carbazole, quinolines, fluoranthene. Many of these constituents are known carcinogens.

Derivatives

Various phenolic coal tar derivatives have analgesic (pain-killer) properties. These included acetanilide, phenacetin, and paracetamol aka acetaminophen. Paracetamol may be the only coal-tar derived analgesic still in use today. Industrial phenol is now usually synthesized from crude oil rather than coal tar.

Coal tar derivatives are contra-indicated for people with the inherited red cell blood disorder glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency), as they can cause oxidative stress leading to red blood cell breakdown.

Mechanism of action

The exact mechanism of action is unknown. Coal tar is a complex mixture of phenols, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic compounds.

It is a keratolytic agent, which reduces the growth rate of skin cells and softens the skin's keratin.

Additional Information

Coal taris a principal liquid product resulting from the carbonization of coal, i.e., the heating of coal in the absence of air, at temperatures ranging from about 900 to 1,200 °C (1,650 to 2,200 °F). Many commercially important compounds are derived from coal tar.

Low-temperature tars result when coal, peat, lignite, or wood are carbonized at temperatures not exceeding 700 °C (1,300 °F). Tar acids, phenolic compounds that react with caustic soda to form water-soluble salts, are extracted from coal tar after it has been distilled.

Tar bases are the alkaline constituents of distillate oils, remaining after tar acids have been removed. One of the bases that is recovered is pyridine, a colourless nitrogenous liquid that has a pungent odour and produces derivatives that are of pharmaceutical value. Pitch is the material remaining after the removal of pyridine and other distillates; it is useful in the aluminum industry for the manufacture of electrodes.

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