Arena, which include toluene, can be considered as derivatives of the founder and first member of the homologous series - benzene.The general formula of compounds which belong to this class, - CnH2n-6.In the molecules of aromatic hydrocarbons contained benzene ring (cycle core).Formula toluene C7H8 reflects the substance belongs to the large group of organic compounds.Many toluene is known by another name - methylbenzene.The substance is widespread in the industry, it is used as the organic solvent, and stain remover for other purposes.
What is toluene?
One of the most important stage - Toluene - is a methyl derivative of benzene.Insoluble in water, colorless liquid has a sweet aroma, reminiscent of the smell of paints, varnishes, solvents.
chemical formula of toluene - C7H8 - can be written differently: C6H5-CH3.In this case, the number of atoms is the same but contrast markedly benzene which is the radical - methyl.
Using other terminology principles, methylbenzene and a compound called fenilmetanom.This is the same toluene, a common formula is C7H8.In the former case it focuses on the fact that one hydrogen atom from those associated with the carbon of the benzene ring is substituted with a methyl radical.For the second name chosen a different approach.It is believed that methane one hydrogen is replaced by a phenyl radical.This particle, which is converted benzene, giving the hydrogen atom.
structure of the molecule
composition of organic matter, which consists solely of carbon and hydrogen, the formula reflects the toluene.Sharosterzhnevye and solid models give an idea of the structure of the molecules of the compound, its difference from the substances of the same homologous series.There are similarities between toluene and benzene, which is the presence of a ring of 6 carbon atoms in the state sp2-hybridization.Each of these three forms sigma bonds with neighboring particles (the two carbon atoms and one hydrogen).Perpendicular to the ring appears unified electronic system of the remaining non-hybrid p-orbitals (one in six carbon atoms).The result becomes a significant strength and stability of the entire cycle, and hence the substance toluene.The structural formula of the compound comprises seven carbon from the methyl group, which is able to sp3-hybridization.It is associated with three hydrogen atoms, and the fourth connection spends compound with one carbon in the benzene ring.
Structural Formula methylbenzene
electron density between the carbon atoms that form the aromatic ring, is distributed evenly.The phenomenon is reflected in the formula of benzene, toluene, and other familiar arenes aromaticity (the circumference of the ring).It is noted the presence of a methyl radical and one of the carbon atoms in the nucleus.Communication between all the particles show dashes.The structural formula in this case reflects the composition of the basic features of the molecular structure of the substance.
simplified formula of toluene - a hexagon with a ring inside or dashes, represents a double bond.The methyl group can be at any of the six atomic nucleus, they are equal to each other.The disadvantage of this method is obvious image.Record does not provide information on the composition of matter and the equivalence of all carbon-carbon bonds in the ring.
Getting methylbenzene in the laboratory and industry
Laboratory toluene was first obtained in the years 1835-1938 P. Pelletier and A. Deville.The first scientists to distillation of pine gum, and the second used tolu balsam extracted from the South American tree Toluifera in Colombia.Thus arose the trivial name of the substance - toluene.Currently, a considerable amount of methylbenzene gives distillation of coal tar oil and followed by purification.During coking toluene is removed from the coke oven gas.In the synthesis of styrene it is released as a byproduct of the reaction of benzene and ethylene.In the laboratory and industrial production of toluene was carried out by different methods.
- dehydrocyclization of acyclic hydrocarbons.Toluene was prepared from heptane in the presence of a catalyst at a temperature of 300 ° C.
- alkylation of benzene, which was called Friedel-Crafts reaction.Carried out in the presence of AlCl3 catalyst or other catalysts: C6H5-H + SN3Cl = C6H5-CH3 + HCl.
- Interaction with bromobenzene: C6H5 CH3-Br +-Br + 2Na = C6H5-CH3 + 2NaBr.
- mixing zinc and cresol: C6H4CH3OH + Zn = C6H5CH3 + ZnO.
- Processing toluene sulfonic acid.
physical properties of methylbenzene
Toluene, the structural formula of which contains a benzene nucleus, shows the physical properties of typical aromatic compounds.
- clear, colorless liquid emits the smell of paint.
- methylbenzene hardens at low temperatures and melts at -93 ° C.
- boiling point of toluene is 110,63 ° C.The density of matter - 0.8669 g / ml.
- methylbenzene solubility in water at 20 ° C - 0.47 g / l.The molar mass of substance M (C7H8) = 92,14 g / mol.
chemical properties of toluene: oxidation
Features all the arena defined chemically stable cycle of six carbon atoms.Formula toluene - is a benzene ring which is formally unsaturated and methyl radical.Aromatics properties close to alkenes, which are characterized by an addition reaction.However, the hydrogen atoms in the molecules of benzene and its homologues, can participate in substitution reactions, which brings the arena and alkanes.Toluene is more reactive than benzene.For substances characterized by the oxidation reaction.
- Burning, which is accompanied by the release of carbon dioxide, and form water: C7H8 + 9O2 = 7CO2 + 4H2O.
- In the reaction of toluene with potassium permanganate oxidation of the methyl group in the side chain of the molecule to carboxyl substance.The reaction of benzoic acid is obtained.
Chemical reactions of the aromatic ring of toluene
- Bromination, which is conducted in the presence of catalysts.Formed halogenated compound: C7H8 + Br2 = C7H7Br + HBr.Nitration
- methylbenzene performed with a mixture of concentrated nitric and sulfuric acids.Nitro toluene can occupy the ortho and para position.The reaction proceeds according to the mechanism of electrophilic substitution.At high temperatures, formed the explosive trinitrotoluene (TNT).
- hydrogenation with hydrogen on a catalyst leads to dearomatization and obtaining methylcyclohexane: C7H8 + 3H2 = C7H14.
- chlorination under strong heating or under the influence of UV radiation culminates in the formation of hexachlorocyclohexane.
Application methylbenzene
Toluene is widely used as a starting material in organic synthesis.It is an essential material in the production of many substances.The use of toluene:
- receipt colorings;
- manufacturing stain removers, detergents;
- production of explosives TNT;
- use as solvent adhesives, paints, synthetic perfume and cleaning agents;
- manufacture of paints for construction works;
- output polish;
- pharmaceuticals;
- increase octane fuel;
- organic synthesis benzoic acid, benzaldehyde, benzyl chloride, saccharin, benzyl alcohol and other substances;
toluene acts as an industrial solvent in the dry cleaners, used in leather tanning.It is a precursor of several petroleum products, phenol formaldehyde, pesticides and other compounds.
toxicity of toluene
methylbenzene is a fire hazard substance.The steam-air mixture explodes under certain conditions.Highly flammable liquid toluene.The structural formula gives an idea of the composition and structure, but does not contain information on the effects of substances on the human body.It is found that toluene is toxic, carcinogenic action.Couples methylbenzene easily penetrate through the skin, respiratory system, cause changes in the central nervous system, irritation of the covering tissue, dermatitis.Inhalation of toluene vapors in humans manifests lethargy, tremors, impaired activity of the vestibular apparatus.Work with toluene, paints, solvents need rubber gloves, thoroughly ventilate the room, or use the hood.Methylbenzene is a weak narcotic substance, substance abuse is toluene.Other adverse effects of substances:
- eye irritation and disturbance of color vision;
- prolonged exposure may cause hearing loss;
- high concentration in the blood causes damage to the liver, kidney necrosis;
- inhalation of large amounts of vapor causes dizziness, drowsiness, headache.
Conclusion
Toluene in large quantities produced in petrochemical plants, or obtained as a by-product coke plants.The compound is a valuable raw material for large-scale organic synthesis used in the pharmaceutical industry.Included methylbenzene of many kinds of solvents, which are applied in dealing with paints.Toluene is in the classification of toxic compounds to III class of danger.When working with a substance concentration of vapor in air should not exceed the values defined by sanitary norms.We can not allow the handling of toluene appearance of open flames, sparks, which may cause an explosion.There are also environmental problems associated with the release into the atmosphere of toluene:
- by burning oil, different fuels;
- in active volcanoes;
- in forest fires;
- using solvents and paints.
toxic properties of toluene, fire and explosion hazards require precautionary treatment of liquid substance and its vapors.
