Benzene and its derivatives

A substance composed of several CH2 groups with similar structure and different molecular composition.

2. The general formula of homologues of benzene:

CnH2n-6 (n≥6)

The main use of benzene is to produce ethylbenzene, followed by cyclohexane and phenol. A series of compounds produced by substitution reaction, addition reaction and oxidation reaction of benzene can be used as raw materials for manufacturing plastics, rubber, fibers, dyes, detergents and pesticides. About 10% benzene is used as the basic raw material for manufacturing benzene intermediates. In addition, benzene has good solubility and can be used as a solvent in chemical production.

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What kind of substance is benzene?

Benzene is a colorless liquid with a special taste and a boiling point of 80. 1℃. Toluene and xylene are homologues of benzene, both of which are products of coal tar fractionation or petroleum cracking. At present, toluene and xylene are often used as solvents or diluents for various adhesives, paints and waterproof materials in interior decoration, instead of pure benzene. Because it is volatile, flammable and explosive. Inhalation of toluene and xylene with high solubility in a short time may lead to central nervous system anesthesia, which is manifested as dizziness, headache, nausea, chest tightness, fatigue, confusion, and even coma and death due to respiratory and circulatory failure. If you are exposed to toluene and xylene with certain solubility for a long time, it will cause chronic poisoning and neurasthenia-like syndrome such as headache, insomnia, listlessness and memory loss. Benzene compounds have been identified as strong carcinogens by the World Health Organization.

Where does benzene mainly come from in homes and office buildings?

Benzene in home and office buildings mainly comes from a large number of chemical raw materials used in building decoration, such as paints, fillers, various organic solvents, etc., which contain a large number of organic compounds and volatilize indoors after decoration. Mainly focused on the following decorative materials:

1. Draw. This compound is mainly volatilized from paint, and benzene, toluene and xylene are indispensable solvents in paint.

2. Additives and diluents for various paints and coatings. Benzene exists in a large number of organic solvents in various building decoration materials, such as natural water in decoration, release materials, etc. The main components are benzene, toluene and xylene.

3. Various adhesives. In particular, solvent-based adhesives still have a certain market in the decoration industry. Most of the solvents used are toluene, and the benzene content is above 30%. However, due to reasons such as price, solubility and adhesiveness, they are still adopted by some enterprises. Some sofas bought by families release a lot of benzene, mainly because of the use of adhesives with high benzene content in production.

4. Waterproof materials, especially some waterproof coatings made of raw powder and released materials, are tested after running for 15 hours, and the benzene content in indoor air exceeds the highest concentration allowed by the state 14.7 times.

5. Some boycotted fake paints are also important reasons for the excessive benzene content in indoor air.

What harm does benzene do to human body?

1. Chronic benzene poisoning is mainly due to the irritating effect of benzene on skin, eyes and upper respiratory tract. Frequent exposure to benzene can make the skin dry and desquamate due to degreasing, and allergic eczema appears in some cases. According to the statistics of Tianjin Hospital, some patients have allergic dermatitis, laryngeal edema, bronchus, thrombocytopenia and other symptoms, all of which are related to the indoor harmful gas exceeding the standard during decoration. Experts call it compound allergy.

2. Long-term inhalation of stupidity will lead to aplastic anemia. At the early stage, bleeding similar to scurvy appeared in the gums and nasal mucosa, and neurasthenia symptoms appeared, such as dizziness, insomnia, fatigue, memory loss, and decreased thinking and judgment. Leukopenia and thrombocytopenia will occur in the future, which will seriously hinder bone marrow hematopoietic skills and lead to aplastic anemia. If the hematopoietic function is completely destroyed, fatal granular leukopenia can occur and leukemia can be caused. In recent years, many labor hygiene data show that the incidence of aplastic anemia is very high among workers exposed to benzene mixture for a long time.

3. Women are more sensitive to the hazards of benzene and its homologues than men, and toluene and xylene also have certain effects on reproductive function. Long-term inhalation of benzene by women of childbearing age can also lead to abnormal menstruation, mainly manifested as menorrhagia or disorder. At first, they often went to the hospital because of menorrhagia or menstrual bleeding, and were often misdiagnosed as uterine bleeding in functional habits, delaying treatment. Exposure to the mixture of toluene, xylene and benzene during pregnancy significantly increases the incidence of pregnancy complications such as pregnancy-induced hypertension syndrome, pregnancy vomiting and pregnancy anemia. According to expert statistics, the spontaneous abortion rate of experimenters and workers exposed to toluene has increased significantly.

4. Benzene can cause fetal congenital defects. This problem has attracted the attention of experts at home and abroad. Western scholars have reported that many babies born to women who inhaled a lot of toluene throughout pregnancy suffered from microcephaly, central nervous system dysfunction and growth retardation. Animal experiments conducted by experts have also proved that toluene can enter the fetus through the placenta, and the toluene content in the blood of fetal rats can reach 75% of that of maternal rats, which makes fetal rats lose weight and delay ossification.

How to prevent the harm of benzene in indoor air?

1. Selection of decorative materials. In decoration, try to use decoration materials that meet national standards and have less pollution, which is the root of indoor air content in the home. For example, use paints, glues and coatings produced by regular manufacturers; Choose water-based materials with no pollution or less pollution; At the same time, remind everyone to pay attention to the regulations on adhesives. Ordinary people have no experience, and decoration companies can use it as they want, which is easy to be ignored.

2. Selection of construction technology. Some decoration companies use paint instead of 107 glue to seal the wall, which increases the benzene content in the indoor air. In addition, when painting waterproof, the construction technology is not standardized, which greatly increases the benzene content in indoor air. Some residents have reported that the building of a decoration company is full of peculiar smell. This kind of high-concentration benzene in the air is very dangerous, which not only makes people poisoned, but also easily leads to explosions and fires.

3. The choice of decoration company. To choose a decoration company with green environmental protection signs, please indicate the indoor environment requirements when signing the renovation contract, especially for the elderly, children and families with allergies. Now some green decoration companies have adopted paint-free technology, which greatly reduces indoor harmful gases.

4. Keep the indoor air clean. This is an effective way to remove indoor harmful gases, and effective indoor air purifiers and ventilation devices can be selected. Or open the window for ventilation when the outdoor air is good, which is beneficial to the emission and discharge of indoor harmful gases.

Don't move into the decorated room immediately. After the decoration of the living room is completed, keep the house well ventilated and stay until benzene and organic matter are released for a period of time.

6. The labor protection of construction workers should be strengthened. When benzene, toluene and xylene volatilize, pay attention to ventilation as much as possible. In order to reduce the harm of benzene in the air of workplace to human body.

Benzene is a colorless, transparent, aromatic and volatile toxic liquid, which is the product of coal tar distillation or petroleum cracking. Benzene vapor can be volatilized at room temperature, and the higher the temperature, the greater the volatilization. In professional activities, benzene mainly enters the human body through the respiratory tract in the form of steam. Inhalation of high-concentration benzene vapor for a short time and low-concentration benzene vapor for a long time will cause physical harm to workers.

Inhalation in a large amount in a short period of time can cause acute mild poisoning, which is characterized by headache, dizziness, cough, chest tightness, excitement and stumbling gait. At this time, if you continue to inhale, it can develop into severe acute poisoning. The patient is confused, his blood pressure drops, his muscles tremble, his breathing is shallow, and his pulse is fast and weak. Timely rescue can restore health in hours or days, but severe cases can also die of respiratory center paralysis.

Long-term low-concentration exposure can lead to chronic poisoning, and symptoms gradually appear, mainly including blood system and neurasthenia syndrome, which is characterized by leukopenia, platelet and red blood cell reduction, dizziness, headache, memory loss, insomnia and so on. In severe cases, aplastic anemia, even leukemia and death may occur.

Occupational acute benzene poisoning is a systemic disease mainly manifested by central nervous system inhibition caused by workers inhaling large doses of benzene vapor in a short period of time during occupational activities. Occupational chronic benzene poisoning refers to a systemic disease with hematopoietic system damage as the main manifestation caused by workers' long-term exposure to benzene vapor in occupational activities.

In recent years, occupational benzene poisoning accidents in China mostly occurred in shoemaking, luggage, toys, electronics, printing, furniture and other industries, and were mostly caused by benzene-containing adhesives, natural water, hardened water, detergents, boiling water, paints and so on. Low concentration of benzene in the air can cause benzene poisoning by inhalation through respiratory tract or direct contact with benzene and its mixture through skin. In these industries, other organic solvents can completely replace benzene, so it is the key to prevent benzene poisoning to replace benzene-containing raw materials with benzene-free raw materials. Pingzhou, Nanhai District, Foshan City is one of the regions with the largest number of leather shoes manufacturers. Since 2000, the leaders of Pingzhou, the health supervision department of Nanhai District, have comprehensively promoted the use of benzene-free adhesives in their jurisdictions and achieved good results.

On-site protection of benzene operation is mainly to strengthen ventilation and personal protection of employees, and workers can wear gas supply gas masks or gas masks. Patients with hematological diseases, liver and kidney diseases and asthma are not suitable for benzene operation.