Толуол: қасиеттері, қолданылуы және химиялық тарихы

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Toluene ('/t//ɒ//l//.//j//u//i://n/), also known as toluol ('/t//ɒ//l//.//j//u//.//ɒ//l//, // //ɔː//l//, // //oʊ//l/), is a substituted aromatic hydrocarbon and has the potential of causing severe neurological harm.

The compound was first isolated in 1837 through a distillation of pine oil by Pierre Joseph Pelletier and Filip Neriusz Walter, who named it rétinnaphte. In 1841, Henri Étienne Sainte Claire Deville isolated a hydrocarbon from balsam of Tolu (an aromatic extract from the tropical Colombian tree Myroxylon balsamum), which Deville recognized as similar to Walter's rétinnaphte and to benzene; hence he called the new hydrocarbon benzoène. In 1843, Jöns Jacob Berzelius recommended the name toluin. In 1850, French chemist Auguste Cahours isolated from a distillate of wood a hydrocarbon which he recognized as similar to Deville's benzoène and which Cahours named toluène.

The distance between carbon atoms in the toluene ring is 0.1399 nm. The C CH3 bond is longer at 0.1524 nm, while the average C H bond length is 0.111 nm.

Toluene reacts as a normal aromatic hydrocarbon in electrophilic aromatic substitution. Because the methyl group has greater electron releasing properties than a hydrogen atom in the same position, toluene is more reactive than benzene toward electrophiles. It undergoes sulfonation to give p toluenesulfonic acid, and chlorination by Cl2 in the presence of FeCl3 to give ortho and para isomers of chlorotoluene. Nitration of toluene gives mono , di , and trinitrotoluene, all of which are widely used. Dinitrotoluene is the precursor to toluene diisocyanate, a precursor to polyurethane foam. Trinitrotoluene (TNT) is an explosive. Complete hydrogenation of toluene gives methylcyclohexane. The reaction requires a high pressure of hydrogen and a catalyst.

Toluene is miscible (soluble in all proportions) with ethanol, benzene, diethyl ether, acetone, chloroform, glacial acetic acid and carbon disulfide, but immiscible with water.

Toluene occurs naturally at low levels in crude oil and is a byproduct in the production of gasoline by a catalytic reformer or ethylene cracker. It is also a byproduct of the production of coke from coal. Final separation and purification is done by any of the distillation or solvent extraction processes used for BTX aromatics (benzene, toluene, and xylene isomers).

It is widely used in the paint, dye, rubber, chemical, glue, printing, and pharmaceutical industries as a solvent. Nail polish, paintbrush cleaners, and stain removers may contain toluene. Manufacturing of explosives (TNT) uses it as well. Toluene is also found in cigarette smoke and car exhaust. If not in contact with air, toluene can remain unchanged in soil or water for a long time. Toluene is a common solvent, e. g. for paints, paint thinners, silicone sealants, many chemical reactants, rubber, printing ink, adhesives (glues), lacquers, leather tanners, and disinfectants. In Australia in 2003, toluene was found to have been illegally combined with petrol in fuel outlets for sale as standard vehicular fuel. Toluene incurs no fuel excise tax, while other fuels are taxed at more than 40%, providing a greater profit margin for fuel suppliers. The extent of toluene substitution has not been determined.

In the laboratory, toluene is used as a solvent for carbon nanomaterials, including nanotubes and fullerenes, and it can also be used as a fullerene indicator. The color of the toluene solution of C60 is bright purple. Toluene is used as a cement for fine polystyrene kits (by dissolving and then fusing surfaces) as it can be applied very precisely by brush and contains none of the bulk of an adhesive. Toluene can be used to break open red blood cells in order to extract hemoglobin in biochemistry experiments. Toluene has also been used as a coolant for its good heat transfer capabilities in sodium cold traps used in nuclear reactor system loops. Toluene had also been used in the process of removing the cocaine from coca leaves in the production of Coca Cola syrup.

The environmental and toxicological effects of toluene have been extensively studied. Toluene is irritating to the eyes, skin, and respiratory tract. It is absorbed slowly through the skin. It can cause systemic toxicity by inhalation or ingestion. Inhalation is the most common route of exposure. Symptoms of toluene poisoning include central nervous system effects (headache, dizziness, drowsiness, ataxia, euphoria, tremors, hallucinations, seizures, and coma), chemical pneumonitis, respiratory depression, ventricular arrhythmias, nausea, vomiting, and electrolyte imbalances. Inhalation of toluene in low to moderate levels can cause tiredness, confusion, weakness, drunken type actions, memory loss, nausea, loss of appetite, hearing loss, and colour vision loss. Some of these symptoms usually disappear when exposure is stopped. Inhaling high levels of toluene in a short time may cause light headedness, nausea, or sleepiness, unconsciousness, and even death. Toluene is, however, much less toxic than benzene, and as a consequence, largely replaced it as an aromatic solvent in chemical preparation. The US Environmental Protection Agency (EPA) states that the carcinogenic potential of toluene cannot be evaluated due to insufficient information. In 2013, worldwide sales of toluene amounted to about 24.5 billion US dollars. Toluene occurs as an indoor air pollutant in a number of processes including electrosurgery, and can be removed from the air with an activated carbon filter. Similarly to many other solvents such as 1,1,1 trichloroethane and some alkylbenzenes, toluene has been shown to act as a non competitive NMDA receptor antagonist and GABAA receptor positive allosteric modulator. Additionally, toluene has been shown to display antidepressant like effects in rodents in the forced swim test (FST) and the tail suspension test (TST),

Toluene is used as an intoxicative inhalant in a manner unintended by manufacturers. People inhale toluene containing products (e. g., paint thinner, contact cement, correction pens, model glue, etc.) for its intoxicating effect. The possession and use of toluene and products containing it are regulated in many jurisdictions, for the supposed reason of preventing minors from obtaining these products for recreational drug purposes. As of 2007, 24 U. S. states had laws penalizing use, possession with intent to use, and/or distribution of such inhalants. In 2005 the European Union banned the general sale of products consisting of greater than 0.5% toluene.

Several types of fungi including Cladophialophora, Exophiala, Leptodontidium (syn. Leptodontium), Pseudeurotium zonatum, and Cladosporium sphaerospermum, and certain species of bacteria can degrade toluene using it as a source of carbon and energy.