overview

Toluene, an organic compound with the chemical formula C7H8, is a colourless, volatile liquid with a peculiar aromatic odour. It has strong refractive properties. It is miscible with ethanol, ether, acetone, chloroform, carbon disulphide and glacial acetic acid and is very slightly soluble in water. Flammable, the vapour forms explosive mixtures with air and the mixture can explode at low volume concentrations. Low toxicity, LD50 (rat, oral) 5000mg/kg. high concentration of gas is narcotic and irritating.

Application

Toluene is mainly produced from crude oil by petrochemical processes. As a solvent it is used in oils, resins, natural and synthetic rubber, coal tar, asphalt, cellulose acetate, as well as in cellulose paints and varnishes, and as a solvent for photographic plates and inks. Toluene is also a major raw material for organic synthesis, especially for chlorinated benzoyl and phenyl, saccharin, trinitrotoluene and many dyes. It is also a component of aviation and automotive gasoline. Toluene is volatile and is relatively resistant to reaction in the environment. It is widely distributed in the environment due to the movement of air and is recirculated intermittently between air and water bodies by rain and evaporation from water surfaces, and may eventually be degraded by biological and microbial oxidation. A summary of average air concentrations in many cities around the world shows that toluene concentrations are typically 112.5-150 μg/m3, mainly from petrol-related emissions (car exhaust, petrol processing), but also from solvent losses and emissions from industrial activities.

Toluene is used in large quantities as a solvent and as an additive to high-octane gasoline, and is also an important raw material for organic chemicals, but is currently produced in relatively excess compared to the benzene and xylenes obtained from both coal and oil, so that a considerable amount is used for dealkylation to benzene or for differentiation to xylenes. A range of intermediates derived from toluene are widely used in the production of fine chemicals such as dyes; pharmaceuticals; pesticides; pyrotechnics; auxiliaries; fragrances and also in the synthetic materials industry. The side chain chlorination of toluene yields monochlorobenzyl, dichlorobenzyl and trichlorobenzyl, including their derivatives benzyl alcohol, benzaldehyde and benzoyl chloride (generally also obtained from the photogasification of benzoic acid), which are widely used in the synthesis of pharmaceuticals, pesticides, dyestuffs and especially fragrances. The cyclic chlorination products of toluene are intermediates in pesticides; pharmaceuticals; and dyes. The oxidation of toluene gives benzoic acid, which is an important food preservative (mainly using its sodium salt) and is also used as an intermediate in organic synthesis. Toluene and benzene derivatives are sulphonated to produce intermediates, including p-toluenesulphonic acid and its sodium salt; CLT acid; toluene-2,4-disulphonic acid; benzaldehyde 2,4-disulphonic acid; toluenesulphonyl chloride, etc., which are used as additives in detergents, anti-caking additives in fertilisers; organic pigments; pharmaceuticals; and dyestuff production. The nitration of toluene produces a large number of intermediates. Many end products can be derived, of which the most important are in polyurethane products, dyes and organic pigments, rubber auxiliaries, pharmaceuticals, explosives, etc.

First aid measures

Skin contact: Remove contaminated clothing and rinse skin thoroughly with soapy water and water.

Eye contact: Lift eyelids and flush with running water or saline. Seek medical attention.

INHALATION: Remove quickly from the scene to fresh air. Keep airway open. If breathing is difficult, give oxygen. If breathing stops, give immediate artificial respiration. Seek medical attention.

Ingestion: Drink sufficient warm water to induce vomiting. Seek medical attention.

Firefighting measures

Hazardous characteristics: flammable, its vapour and air can form an explosive mixture, in contact with open flame, high heat can cause combustion and explosion. It can react strongly with oxidising agents. The flow rate is too fast and it is easy to generate and accumulate static electricity. The vapour is heavier than air and can diffuse at a lower level to a considerable distance, and will ignite back when exposed to an ignition source.

Harmful combustion products: carbon monoxide, carbon dioxide.

Extinguish the fire by spraying water to cool the container and, if possible, moving it from the fire to an open area. Containers in the fire must be evacuated immediately if they have changed colour or if sound is produced from the safety relief device.

Extinguishing agents: foam, dry powder, carbon dioxide, sand and soil. Water is not effective.

Emergency response to spills

Quickly evacuate people from the spill contaminated area to a safe area and isolate and strictly limit access. Cut off the source of ignition. Advise emergency responders to wear self-contained positive pressure respirators and gas-protective clothing. Cut off the source of the spill if possible. Prevent flow into restricted spaces such as sewers and flood drains.

Small spill: absorb with activated carbon or other inert material. You can also scrub with an emulsion made from a non-flammable dispersant and dilute the wash into the waste water system.

Large spills: Construct a berm or dig a pit to contain it. Cover with foam to reduce the vapour hazard. Transfer to a tanker or special collector with an explosion-proof pump for recycling or transport to a waste disposal site.

Storage method

Storage precautions: Store in a cool, ventilated warehouse. Keep away from fire and heat sources. The temperature should not exceed 30°C. Keep containers sealed. Store separately from oxidising agents and do not mix. Use explosion-proof lighting and ventilation facilities. Do not use spark-prone machinery and tools. The storage area should be equipped with spill response equipment and suitable shelter materials.