At room temperature benzene is presented as a colorless, sweet transparent liquid, with strong aromatic order, a density (0.88g/ml) lower than that of water but greater molecular mass. Its boiling point and melting point are 80.1℃ and 5.5℃ respectively. Although Benzene is poorly soluble in water (maximum 1.7g of benzene can be dissolved by 1 litter of water), it is a good organic solvent that can easily dissolve organic molecules and some non-polar inorganic molecules. It is miscible in most organic solvents other than glycerol and ethylene glycol. Except that iodine and sulfur slightly dissolve in benzene, other inorganic substances are insoluble.
When benzene reacts with water, azeotrope with a boiling point of 69.25℃ and a benzene content of 91.2% can be generated. Therefore, benzene is usually added into the water-generating reaction for distillation, so as to discharge the water.
As the benzene can reduce knocking, it can serve as a gasoline additive. Before the use of tetraethyl lead kicked off in the 1950s, all antiknock agents were nothing else but benzene. However, with the fading out of leaded petrol, benzene was reused. Due to its detrimental effect on human health and contamination on ground water quality, western countries limit the benzene content in gasoline within 1%.
The most important industrial use of benzene is as a chemical raw material, as it can be synthesized into a serious of derivatives:
Benzene is primarily used for producing ethylbenzene and secondly for cyclohexane and phenol.
A series of compounds generated by benzene-involving substitution reaction, addition reaction and oxidation reaction can be sued as raw material for producing plastics, rubber, fiber, dye, detergent and insecticide etc. About 10% of the benzene is used for producing the basic raw material for intermediate of benzene series.
Moreover, with its good dissolving property, benzene can still serve as solvent for chemical industry production.