Dichloromethane (DCM), with the chemical formula CH ₂ Cl ₂, is a colorless, volatile, and slightly sweet organic solvent. It is a liquid at room temperature and pressure, with a boiling point of 39.8 ℃, a melting point of -95.1 ℃, and a density of 1.325 g/cm ³. It is insoluble in water but easily soluble in most organic solvents such as ethanol, ether, and benzene. It is a widely used basic chemical raw material in the chemical industry.
1、 Basic physical and chemical properties
Dichloromethane is a halogenated hydrocarbon formed by replacing two hydrogen atoms in methane molecules with chlorine atoms. It has a stable molecular structure, relatively mild chemical properties, and is not easy to burn (flash point -14.1 ℃, non flammable). However, it may decompose into toxic phosgene and hydrogen chloride gases at high temperatures, open flames, or in contact with oxidants. Therefore, the storage and use environment should be strictly controlled.
Its nuclear psychological characteristics determine its application scenarios: it has strong volatility and excellent solubility, and can dissolve most organic compounds, including fats, oils, resins, rubber, etc; Non flammability gives it an advantage in replacing flammable solvents; At the same time, its boiling point is low, making it easy to recover through distillation, reusable, and reducing usage costs.
2、 Main purpose
The application of dichloromethane covers multiple fields such as chemical engineering, pharmaceuticals, electronics, coatings, and environmental protection. It is an indispensable organic solvent and chemical intermediate in industrial production. Its specific uses are as follows:
1. Solvent field: As an excellent organic solvent, it is widely used as a diluent for coatings, paints, and adhesives, which can improve the leveling and adhesion of coatings; Simultaneously used for metal cleaning and degreasing of electronic components, it can quickly remove oil stains and impurities without damaging the substrate, suitable for precision cleaning of semiconductors and electronic components.
2. Pharmaceutical field: Used for the synthesis of pharmaceutical intermediates, as well as drug extraction and purification processes, such as the production of antibiotics, vitamins and other drugs. It can be used as an extractant to separate active ingredients and improve product purity; In addition, it can also be used for the preparation of local anesthetics.
3. Chemical synthesis: As an important chemical intermediate, it is used to produce chemical products such as trichloromethane, carbon tetrachloride, dichloroethane, and is also a raw material for synthesizing polymer materials such as polycarbonate and polyurethane. It is widely used in the plastic and rubber industries.
4. Other fields: Used for the extraction of food additives (such as caffeine, spices, etc.), as well as wastewater treatment and soil remediation in the field of environmental protection. It can be used to extract organic pollutants from wastewater and achieve the separation and recovery of pollutants.
3、 Safety and environmental precautions
Dichloromethane has certain toxicity, and long-term or high concentration exposure can cause harm to human health, mainly affecting the central nervous system. Symptoms such as dizziness, headache, nausea, and vomiting may occur, and long-term exposure may also damage organs such as the liver and kidneys; Meanwhile, its volatile gases may cause pollution to the atmospheric environment and have been included in the "Key Control New Pollutant List (2023 Edition)", which is subject to strict control.
Precautions for use and storage:
1. Wear protective masks, gloves, goggles and other protective equipment during operation to avoid direct skin contact and inhalation of its vapors. The operating environment should be well ventilated and equipped with exhaust gas recovery devices.
2. Store in a cool, dry, and ventilated warehouse, away from fire and heat sources, avoid mixing with oxidants, strong alkalis, metal powders, and other substances to prevent chemical reactions.
3. Waste disposal must comply with environmental standards and cannot be dumped at will. Professional institutions should be commissioned for harmless treatment to avoid polluting soil and water sources.
4、 Industry control and development trends