Dichloromethane has the advantages of strong solubility and low toxicity, and is widely used in the manufacture of safety film films and polycarbonates, and the rest are used as paint solvents, metal degreasers, gas smoke propellants, polyurethane foaming agents, mold release agents, and degreasing agents. Lacquer. Dichloromethane is a colorless liquid, used as a reaction medium in the pharmaceutical industry for the preparation of ampicillin, oxybenicillin and cephalosporin, etc.; also used as a solvent in film production, petroleum dewaxing solvent, aerosol propellant, Organic synthesis extractant, foaming agent and metal cleaning agent for the production of foamed plastics such as polyurethane. Dichloromethane is mainly used in film production and pharmaceutical fields in China. Among them, the consumption for film production accounts for 50% of the total consumption, the pharmaceutical industry accounts for 20% of the total consumption, the cleaning agent and chemical industry consumption accounts for 20% of the total consumption, and other aspects account for 10%.
Dichloromethane is also used as a refrigerant in industrial refrigeration systems, but it is very harmful, and can produce highly toxic phosgene when it comes into contact with open flames or hot objects. In case of humid air, it can be hydrolyzed to generate a small amount of hydrogen chloride, and light can also promote hydrolysis and increase the corrosiveness to metals. For grain fumigation and refrigeration of low-pressure freezers and air-conditioning units. It is used as an auxiliary blowing agent in the production of polyether urethane foam, and as a blowing agent for extruded polysulfone foam.
Dichloromethane – Properties
Colorless transparent volatile liquid. Has a pungent odor similar to ether. Soluble about 50 times of water, soluble in phenol, aldehyde, ketone, glacial acetic acid, triethyl phosphate, ethyl acetoacetate, cyclohexylamine. Mixed with other chlorinated hydrocarbon solvents and ethanol, ether and N,N-dimethylformamide
dissolve. Relative density 1.3266. Melting point -9 5.1 ℃. Boiling point 40 ℃. The auto-ignition point is 640°C. Viscosity (20℃) 0.43mPa. s. Refractive index 1.4244. Critical temperature 245 ℃. 171MPa。 Critical pressure 6. 171MPa. After pyrolysis, HCl and a trace amount of phosgene are generated, which are heated with water for a long time to generate formaldehyde and HCl. Further chlorination can obtain CHCl3 and CCl4.