What is benzene? What are its uses and hazards?

Benzene picture Image: Benzene structural formula In the early 19th century, gas was already widely used in urban lighting in Europe. While producing gas, there was also an oily liquid that no one cared about. Faraday was very interested in this liquid. In 1825, he separated the oily liquid by distillation to obtain benzene. Benzene is an organic compound with the simplest structure of aromatic hydrocarbons. According to chemical source network data, its chemical formula is C6H6, molecular weight is 78.112, melting point is 5.5 degrees Celsius, boiling point is about 78.8 + 8 degrees Celsius, and it is a colorless and transparent liquid at room temperature. It has a strong aroma, sweet taste, flammable and carcinogenic toxicity. It is insoluble in water and easily soluble in most organic solvents such as ethanol, ether, and acetone. It is also an organic solvent in itself. Benzene is a ring-like structure, which is also known as the Kekule structure. The discovery of the Kekule structure has always been one of the famous anecdotes in the history of chemistry. In 1890, at a conference to celebrate the 25th anniversary of Kekule's discovery of the benzene ring structure in Berlin's City Hall, he said in a speech that when he discovered the benzene structure, he was teaching at the University of Ghent in Belgium. One night, he dozed off in his study, and the spinning carbon atoms appeared before his eyes. The long chain of carbon atoms coiled up like a snake, and the snake's mouth suddenly bit its tail and spun non-stop. He woke up abruptly, and after experimental verification, he finally put forward the conjecture of the benzene ring structure. Benzene is widely used in the production of synthetic rubber, synthetic resins, synthetic fibers, organic pigments, synthetic detergents, dyes, medicines, fragrances, pesticides, etc., and is also often used in heat carriers and solvents. As early as the 1920s, benzene was a commonly used solvent in industry, mainly for metal degreasing. Its most important use is as a chemical raw material to synthesize a series of benzene derivatives: the raw materials for the production of plastics, rubber, detergents, fibers, dyes, pesticides, etc. usually contain various compounds generated by benzene through substitution reactions, addition reactions, oxidation reactions, etc. Benzene can also be used to make benzene intermediates: benzene and ethylene to form ethylbenzene, which can produce styrene for plastics; benzene and propylene to form cumene, which can produce acetone and phenol for resins and binders; and the production of nylon cyclohexane, maleic anhydride, nitrobenzene for the production of aniline, chlorobenzene, various alkylbenzene and hydroquinone, anthraquinone and other chemical products for the production of detergents and additives. Benzene is a first-class carcinogen, which is relatively toxic. Special attention should be paid to safety when using it. Inhalation of high concentrations of benzene can cause central nervous system reactions, from chest tightening to breathing difficulties to loss of consciousness. Tremors, convulsions, and even death due to respiratory paralysis and circulatory failure can occur within minutes to hours after heavy exposure. Inhalation of small amounts of fluid immediately causes pulmonary edema and bleeding of lung tissue. Short-term direct skin contact can cause erythema, long-term or repeated skin contact can cause dehydration, contractile dermatitis, and secondary skin infections. The hematopoietic system is the main target organ, causing nosebleeds, purple scars, bleeding of the gums and mucous membranes, cytopenia, thrombocytopenia, leukopenia, anemia, and leukemia. There are many methods for preparing benzene, most of which are industrial-grade production and preparation methods. If you do scientific research, you can try to buy reagents from major brands such as Huayuan Mall.