Today, the editor of
Shuochi Chemicalwill introduce to you the preparation method of dichloroethane, hoping to be helpful to you。
1. Direct Synthesis Method of Ethylene and Chlorine: Ethylene and chlorine are chlorinated in a 1,2-dichloroethane medium to produce crude dichloroethane and a small amount of polychlorinated compounds. The mixture is then treated with an alkali and flash evaporated to remove acidic substances and some high-boiling components. It is washed with water until neutral, followed by azeotropic dehydration and distillation to obtain the final product.
2. Ethylene Oxychlorination Method: Ethylene is directly chlorinated with chlorine to produce dichloroethane. During the production of vinyl chloride from the cracking of dichloroethane, hydrogen chloride is recovered and combined with preheated oxygen-containing gas (air) and ethylene at 150-200°C. This mixture passes over a copper chloride catalyst supported on alumina, reacting at a pressure of 0.0683-0.1033 MPa and a temperature of 200-250°C. The crude product is then cooled (causing most of the trichloroacetaldehyde and some water to condense), pressurized, and purified to obtain the dichloroethane product.
3. The method of direct chlorination of ethylene from petroleum cracking gas or coke oven. In addition, there is also a byproduct of 1,2-dichloroethane in the production of ethylene oxide by the chloroethanol method.
4. Industrial product 1,2-dichloroethane is washed with concentrated sulfuric acid until the acid layer becomes colorless, then washed with a 5% solution of calcium hydroxide, and washed again with water to remove the water layer. After drying with anhydrous calcium chloride, carry out distillation. 1,2-dichloroethane can form an azeotropic mixture with water, containing 8.9% water, and has a azeotropic point of 77 ℃. By utilizing this characteristic, a large amount of water is removed and then dried and distilled to obtain pure 1,2-dichloroethane.
5. Suspend the catalyst (ferric chloride, copper chloride, or antimony trichloride) in dichloroethane as the reaction medium. Introduce ethylene gas and chlorine gas into the mixture, maintaining the reaction temperature at 50-70°C and the reaction pressure at 0.4-0.5 MPa. Wash the resulting product with water to remove hydrogen chloride and the catalyst, allowing the mixture to settle and separate. Remove the aqueous layer, then wash with 1-2% sodium hydroxide solution. After removing the aqueous layer again, perform azeotropic distillation. Allow the distilled azeotrope to settle and remove the aqueous layer. Dry the mixture, then distill it to obtain pure 1,2-dichloroethane.
