Dichloromethane 75-09-2

Dichloromethane (DCM) has the advantages of strong solubility and low toxicity, and is widely used in the production of safety film, polycarbonate, and other applications such as paint solvents, metal degreasers, aerosol propellants, polyurethane foaming agents, release agents, and paint removers.

Dichloromethane is a colorless liquid used as a reaction medium in the pharmaceutical industry for the production of ampicillin, amoxicillin, and cephalosporin, among others. It is also used as a solvent in film production, a petroleum dewaxing solvent, an aerosol propellant, an organic synthesis extractant, a foaming agent for polyurethane foam plastics, and a metal cleaner.

In China, dichloromethane is primarily used in film production and the pharmaceutical industry. Film production accounts for 50% of total consumption, pharmaceutical applications account for 20% of total consumption, cleaning agents and the chemical industry account for 20% of total consumption, and other applications account for 10%.

Dichloromethane is also used as a refrigerant in industrial refrigeration systems, but it poses significant hazards. When exposed to open flames or hot objects, it can produce highly toxic phosgene. Exposure to moist air can cause hydrolysis, producing trace amounts of hydrogen chloride, and exposure to light can also promote hydrolysis, enhancing its corrosive effect on metals.

It is used for grain fumigation and in low-pressure refrigeration units and air conditioning systems. It is used as an auxiliary foaming agent in the production of polyether-type urethane foam plastics and as a foaming agent for extruded polyvinyl chloride foam plastics. Dichloromethane is also used to produce decaffeinated coffee. Coffee is first boiled to dissolve the caffeine, which floats to the surface, and then dichloromethane is used to remove the caffeine.

Applications and Functions
The primary application of dichloromethane is as a solvent. Dichloromethane possesses strong solvent properties, a low boiling point, and relatively low toxicity and reactivity, making it the most frequently used organic solvent in organic synthesis. Its role as a solvent is nearly equivalent to that of water in inorganic salt chemistry.

It is extensively used in the production of safety film, polycarbonate, and as a solvent for coatings, metal degreaser, aerosol propellant, polyurethane foam agent, release agent, and paint remover. In the pharmaceutical industry, it serves as a reaction medium for the preparation of ampicillin, amoxicillin, and cephalosporin, among others; it is also used as a solvent in film production, a petroleum dewaxing solvent, an aerosol propellant, an organic synthesis extractant, a foaming agent for polyurethane and other foam plastics, and a metal cleaner.

Due to its steric effect, dichloromethane is inert and typically does not participate in chemical reactions. However, under certain conditions, it can react. An industrial accident occurred where residual dichloromethane reacted with sodium azide in N,N-dimethylformamide to form diazomethane, causing the factory to explode. In China, dichloromethane is primarily used in film production and the pharmaceutical industry.

Film production accounts for 50% of total consumption, pharmaceuticals account for 20%, cleaning agents and the chemical industry account for 20%, and other applications account for 10%.