Name | Mixed benzene |
Synonyms | Mixed benzene |
Appearance | Yellow to brownish transparent viscous liquid |
Use | Mixed benzene is a mixture of various types of benzene, as the simplest aromatic hydrocarbon in the solvent. It is one of the basic raw materials for the organic chemical industry. Colorless, flammable, special odor liquid. Mixed benzene has low melting point, low boiling point, and relative density less than water. The solubility in water is very small, and it can be miscible with organic solvents such as ethanol, ether, and carbon disulfide. Can form a constant boiling mixture with aquatic water. |
Benzene is nitrated with a mixture of nitric acid and sulfuric acid to form nitrobenzene, and nitrobenzene is reduced to form an important dye intermediate aniline; benzene is sulfonated with sulfuric acid to form benzenesulfonic acid, which can be used to synthesize phenol; benzene is in the presence of ferric chloride It reacts with chlorine to produce chlorobenzene, which is an important intermediate; benzene reacts with ethylene, propylene or long-chain olefins in the presence of catalysts such as anhydrous aluminum trichloride to produce ethylbenzene, isopropylbenzene or alk,
Ethylbenzene is the raw material for the synthesis of styrene, cumene is the raw material for the synthesis of phenol and acetone, and alkylbenzene is the raw material for the synthesis of detergents. Benzene is catalyzed by hydrogenation to produce cyclohexane, which is a raw material for the synthesis of nylon resistance; benzene is added with three-molecule chlorine under light to obtain insecticide 666. Because it is toxic to humans and animals, its production and use have been banned. Benzene is difficult to oxidize, but it can be oxidized to maleic anhydride at 450 ℃ and in the presence of vanadium oxide, which is the raw material for the synthesis of unsaturated polyester resin. Mixed benzene is a good solvent for rubber, fat and many resins, but due to its high toxicity, it has gradually been replaced by other solvents. Benzene can be added to gasoline to improve its anti-knock performance.
Benzene is industrially produced by catalytic reforming of naphtha fractions produced by refining petroleum, or recovered from coke oven gas obtained from coking. Benzene vapor is toxic, acute poisoning can cause cramps and even loss of consciousness in severe cases; chronic poisoning can damage hematopoietic function.
In 1865, F.A. Kekule proposed the cyclic structure of benzene, which is still being used. According to the description of quantum chemistry, 6 & pi; electrons in benzene molecules are distributed above and below the ring plane as a whole. Therefore, in recent years, the structure of benzene has also been represented by the formula of Figure 1b. Mixed benzene, etc. is a colorless liquid with a special aromatic smell, which can be miscible with alcohol, ether, acetone and carbon tetrachloride. Mixed benzene is volatile and flammable, and its vapor is explosive. Frequent contact with benzene mixture, the skin can become dry and desquamated due to degreasing, and some have allergic eczema. Long-term inhalation of benzene can cause aplastic anemia. Mixed benzene molecules have a planar regular hexagonal structure. Each bond angle is 120 °, and the bond length between carbon and carbon on the hexagonal ring is 1.40 × 10 -10 meters. It is not only different from the general single bond (C-C key length is 1.54 × 10 -10 meters), but also different from the general double bond (C = C key length is 1.33 × 10 -10 meters). From the fact that benzene does not react with potassium permanganate solution and bromine water and the experimental data of the measured carbon-carbon bond length, it fully shows that the carbon-carbon bond on the benzene ring should be a unique bond between single bond and double bond.