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Dongying Rich Chemical Co.,Ltd

How To Dry Dichloromethane To Anhydrous

    Dichloromethane (methylene dichloride)  M 84.9, b 40.0°, d 1.325, n 1.42456, n251.4201. Shaken with portions of cone H2SO4 until the acid layer remained colourless, then washed with water, aqueous 5% Na2CO3, NaHCO3 or NaOH, then water again. Pre-dried with CaCl2, and distd from CaSO4, CaH2 or P2O5. Stored away from bright light in a brown bottle with Linde type 4A molecular sieves, in an atmosphere of dry N2- Other purification steps include washing with aq Na2S2O3, passage through a column of silica gel, and removal of carbonyl-containing impurities as described under Chloroform. It has also been purified by treatment with basic alumina, distd, and stored over molecular sieves under nitrogen .

    Dichloromethane has the advantages of low dissolving power and low toxicity. It is used in a large amount to make safe film, polycarbonate, and the other is used as paint solvent, metal degreasing agent, air smoke spray, polyurethane foaming agent, releasing agent, Paint agent.Methyl bromide as a colorless liquid, in the pharmaceutical industry as a reaction medium for the preparation of ampicillin, ampicillin and cephalosporin, etc .; also used as film production solvent, oil dewaxing solvent, aerosol propellant, Organic synthesis extractant, polyurethane and other foam production of foaming agent and metal cleaning agent.Dichloromethane in China is mainly used in film production and pharmaceutical fields. Which accounted for 50% of total consumption for film production, 20% of total consumption of medicine, cleaning agents and chemical industry consumption accounted for 20% of total consumption, other aspects accounted for 10%. Dichloromethane is also used in industrial refrigeration systems for use as a refrigerant, but is highly hazardous and can produce highly toxic phosgene when exposed to open flames or burning objects. Humid air can hydrolyze to produce trace amounts of hydrogen chloride, and light can also promote hydrolysis and enhance the corrosiveness of metals.

    For the use of grain fumigation and low pressure refrigerators and air conditioning installations. Is used as an auxiliary blowing agent in the production of polyether urethane foams, and as a foaming agent for extruding polysulfone type foams.

Dichloromethane is also used to make decaffeinated coffee. The coffee is first cooked by cooking to dissolve the caffeine and float on the surface, and then use methylene chloride to remove the caffeine.


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