Толуол

Использование

Толуол применяют как сырье для производства бензола, бензойной кислоты, нитротолуолов (в том числе тринитротолуола), толуилендиизоцианатов (через динитротолуол и толуилендиамин) бензилхлорида и др. органических веществ, для органического синтеза, высооктановых добавок к моторным топливам, в качестве растворителя в лакокрасочной промышленности для растворения тощих алкидов, кремнийорганических, акриловых смол, полистирола, как основной компонент входит в состав смесовых растворителей ( Р-4, Р-4А, Р-5А, 646,647,648, Р-12 ), применяемых для растворения при изготовлении и нанесении эпоксидных, виниловых, акриловых, нитроцеллюлозных, хлоркаучуковых лакокрасочных материалов.

Описание

Toluene is a clear, colourless liquid with a sweet, benzene-like odour. Toluene occurs naturally in crude oil and in the toluene tree. It is also produced in the process of making gasoline and other fuels from crude oil and making coke from coal. Toluene is used in making paints, paint thinners, fingernail polish, lacquers, adhesives, and rubber and in some printing and leather tanning processes. Toluene is also used in the production of polymers used to make nylon, plastic soda bottles, and polyurethanes and for pharmaceuticals, dyes, cosmetic nail products, and the synthesis of organic chemicals.
Toluene has been reported as the most commonly abused hydrocarbon solvent, primarily through ‘glue sniffing’. The common possibilities of exposure to high levels of toluene include indoor air from the use of household products such as paints, paint thinners, adhesives, synthetic fragrances, and many other sources.

Химические свойства

Toluene is a clear, colorless, flammable liquid with a sweet/pungent odor. It is extensively used as a solvent in different industries, i.e., rubber chemical manufacturing, drugs and pharmaceuticals, thinner for inks, paints dyes, and perfume manufacturing. It is a natural constituent of crude oil and is produced from petroleum refi ning and coke-oven operations. Toluene occurs naturally as a component of crude oil and occurs in petroleum refi ning and coke oven operations. Occupational workers associated with several kinds of activities, such as manufacturing of dyes, printing inks, painting automobile mechanics, gasoline manufacturers, shippers, and retailers, adhesives and coatings manufacturers and applicators, audio-equipment product workers, chemical industry workers, coke-oven workers, fabric manufacturers (fabric coating), sites of hazardous wastes, linoleum manufacturers, in pharmaceutical manufacturing, printing works, shoe manufacturing industry, become exposed to toluene.

Физические свойства

Colorless, clear, flammable liquid with a pleasant, sweet or paint-like odor similar to benzene. At 40 °C, the lowest concentration at which an odor was detected were 960 μg/L. Similarly at 25 °C, the lowest concentration at which a taste was detected was 960 μg/L (Young et al., 1996). Experimentally determined detection and recognition odor threshold concentrations were 600 μg/m³ (160 ppb_v) and 7.0 mg/m³ (1.9 ppm_v), respectively (Hellman and Small, 1974). Leonardos et al. (1969) reported higher odor threshold concentrations for toluene derived from coke (4.68 ppmv) and petroleum (2.14 ppm_v). The average least detectable odor threshold concentrations in water at 60 °C and in air at 40 °C were 24 and 140 μg/L, respectively (Alexander et al., 1982). An odor threshold concentration of 330 ppb_v was determined by a triangular odor bag method (Nagata and Takeuchi, 1990). Cometto-Mu?iz and Cain (1994) reported an average nasal pungency threshold concentration of 29,574 ppm_v.

История

Toluene is a clear, flammable, aromatic hydrocarbon liquid with a smell similar to benzene. It is also called methylbenzene, indicating that a methyl group has been added to one of benzene’s carbon atoms. Toluene was first isolated by Pierre-Joseph Pelletier (1788–1842) and Philippe Walter (1810–1847) in 1837. The name toluene comes from the South American tree Toluifera balsamum. Henri-Etienne Sainte-Claire Deville (1818–1881) isolated toluene from the tree’s gum, Tolu balsam, in 1841.
The main source of toluene is from the catalytic reforming of naphthas during petroleum processing. During this process cycloalkanes are dehydrated, forming aromatics such as toluene and xylene along with hydrogen. Toluene can also be obtained from the pyrolysis of gasoline. It is a by-product when styrene is produced and can also be produced from coal tar, which was its main source in the first half of the 20th century.

Использование

Toluene is derived from coal tar as well aspetroleum. It occurs in gasoline and manypetroleum solvents. Toluene is used to producetrinitrotoluene (TNT), toluene diisocyanate,and benzene; as an ingredient fordyes, drugs, and detergents; and as an industrialsolvent for rubbers, paints, coatings, andoils.

Методы производства

Benzene is produced from toluene through a process called hydrodealkylation. In thisprocess, toluene reacts with hydrogen in the presence of a chromium, platinum, or molybdenumcatalysts at temperatures of several hundred degrees Celsius and pressures of about50 atmospheres: C6H5CH3 + H2 → C6H6 + CH4. Toluene can also be used to producephenol, (C6H5OH), benzoic acid (C6H5COOH), and benzaldehyde (C6H5CHO). Nitratedforms of toluene produce explosive compounds; the most common of these is TNT (SeeTrinitrotoluene).

Подготовка

Toluene is the starting material for the production of tolylene diisocyanate (TDI)，the process may be varied to give products of differing isomer contents. The nitration of toluene (with a nitrating mixture containing 20% nitric acid, 60% sulphuric acid and 20% water at 30-45°C) gives a mixture of 2-nitrotoluene (about 60%) and 4- nitrotoluene (40%). If this mixture is nitrated further (with a mixture of 35% nitric acid and 65% sulphuric acid at 65-80°C) without separation, the product is a mixture of2,4-dinitrotoluene (about 80%) and 2,6-dinitrotoluene (20%). If, on the other hand, the mixed mononitrates are separated (by distillation), then further nitration of the 2-nitrotoluene yields a mixture of 2,4-dinitrotoluene (about 65%) and 2,6-dinitrotoluene (35%) whilst further nitration of the 4-nitrotoluene gives only 2,4-dinitrotoluene.

Определение

ChEBI: The simplest member of the class toluenes consisting of a benzene core which bears a single methyl substituent.

Описание

Толуол — подвижная летучая жидкость, не имеющая цвета, с характерным запахом. Смешивается в неограниченных пределах с углеводородами, многими спиртами и эфирами. Горюч, сгорает коптящим пламенем. Пары легко образуют взрывоопасные смеси, воспламеняющиеся даже от искры статического электричества, например от энергии падения растворителя с высоты в пластиковую канистру.

Общее описание

A clear colorless liquid with a characteristic aromatic odor. Flash point 40°F. Less dense than water (7.2 lb / gal) and insoluble in water. Hence floats on water. Vapors heavier than air. May be toxic by inhalation, ingestion or skin contact. Used in aviation and automotive fuels, as a solvent, and to make other chemicals.

Реакции воздуха и воды

Highly flammable. Insoluble in water.

Профиль реактивности

Toluene reacts vigorously with allyl chloride or other alkyl halides even at minus 70° C in the presence of ethyl aluminum dichloride or ethyl aluminum sesquichloride. Explosions have been reported [NFPA 491M 1991]. Incompatible with strong oxidizing agents. When added to a tank of sulfur dichloride, the tank over pressurized and ruptured in a reaction thought to be catalyzed by iron or iron(III) chloride [Chem. Eng. News, 1988, 66(32), 2].

Опасность

Flammable, dangerous fire risk. Explosive limits in air 1.27–7%. Toxic by ingestion, inhalation, and skin absorption. Visual impairment, female reproductive effects, and pregnancy loss. Questionable carcinogen.

Угроза здоровью

Exposures to toluene cause adverse health effects to animals and humans. The symptoms of toxicity and poisoning include, but are not limited to, mild irritation to the skin, headache, nausea, and effects on the CNS. Prolonged exposure to high concentrations of toluene causes disturbances in vision, dizziness, nausea, CNS depression, paresthesia, and sudden collapse. The acute oral LD50 value of toluene in laboratory rats has been reported as 636–7300 mg/kg. Exposure to toluene has been reported to cause rapid and severe corneal damage and conjunctiva infl ammation. The acute dermal LD50 in rabbits was found to be between 1200 and 1400 mg/kg.

Пожароопасность

Toluene is a flammable liquid (NFPA rating = 3), and its vapor can travel a considerable distance to an ignition source and "flash back." Toluene vapor forms explosive mixtures with air at concentrations of 1.4 to 6.7% (by volume). Hazardous gases produced in fire include carbon monoxide and carbon dioxide. Carbon dioxide and dry chemical extinguishers should be used to fight toluene fires.

Воспламеняемость и взрывоопасность

Toluene is a flammable liquid (NFPA rating = 3), and its vapor can travel a considerable distance to an ignition source and "flash back." Toluene vapor forms explosive mixtures with air at concentrations of 1.4 to 6.7% (by volume). Hazardous gases produced in fire include carbon monoxide and carbon dioxide. Carbon dioxide and dry chemical extinguishers should be used to fight toluene fires.

Химическая реактивность

Reactivity with Water No reaction; Reactivity with Common Materials: No reactions; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.

Возможный контакт

Toluene is used as an industrial chemical, chemical intermediate; solvent, and emulsifier; may be encountered in the manufacture of benzene. It is also used as a chemical feed for toluene diisocyanate, phenol, benzyl and benzoyl derivatives; benzoic acid; toluene sulfonates; nitrotoluenes, vinyltoluene, and saccharin; as a solvent for paints and coatings; or as a component of automobile and aviation fuels.

Канцерогенность

The IARC has determined that there is evidence for the lack of carcinogenicity of toluene in experimental animals and that there is inadequate evidence for carcinogenicity in humans. Results of in vitro assays generally indicate that toluene is not genotoxic. Reports of increased incidences of sister chromatid exchanges and chromatid breaks in exposed workers are confounded by concurrent exposure to other organic chemicals.

хранилище

toluene should be used only in areas free of ignition sources, and quantities greater than 1 liter should be stored in tightly sealed metal containers in areas separate from oxidizers.

Перевозки

UN1294 Toluene, Hazard Class: 3; Labels: 3-Flammable liquid.

Несовместимости

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Violent reaction with mixtures of nitric and sulfuric acid.

Утилизация отходов

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.