SYNTHESIS OF VINYL CARBONATE

Synthesis of vinyl carbonate by phosgene method

Phosgene method is the first industrialized method to prepare vinyl carbonate. The process uses ethylene glycol to react directly with phosgene, which is highly toxic and seriously pollutes the environment. This method has been banned in developed countries, but in some developed countries, enterprises still use this method to produce.

Transesterification

The method of preparing vinyl carbonate by transesterification of diethyl carbonate and ethylene glycol is transesterification. The process of this method is not complicated. The key is to find suitable catalysts. In order to reduce the loss of diethyl carbonate in the process of ethanol distillation, increase the reaction temperature and speed up the reaction, tin dibutyllaurate and trace alkali were used as catalysts for transesterification reaction, and by-products (ethanol) were fractionated continuously at the reaction temperature of xylene reflux control system. Then the oligomer was directly added to p-toluene sulfonic acid to neutralize and catalyze the prepolymerization reaction. The oligomer was prepared by high temperature depolymerization under the catalysis of tin powder. The yield of the final product was more than 75%. If cheaper raw materials and more efficient catalysts can be found, the method is still of practical application value.

Addition of Ethylene Oxide to Carbon Dioxide

The addition reaction of ethylene oxide and carbon dioxide to prepare vinyl carbonate is an exothermic and volume-shrinking reaction. From the point of view of chemical equilibrium, low temperature and high pressure conditions are conducive to the reaction, and the selection of suitable catalyst is the key to the smooth operation of the reaction. The reaction system includes homogeneous catalytic system and multiphase catalytic system.

Vinyl carbonate (EC) is an excellent organic solvent, which can dissolve many kinds of polymers. It can also be used as an organic intermediate to replace ethylene oxide for dioxide reaction and is the main raw material for dimethyl carbonate production by transesterification. It can also be used as raw material for synthesis of furazolidone, water glass slurry and fiber finishing. In addition, it is also used in the electrolyte of lithium batteries. Vinyl carbonate can also be used as an active intermediate in the production of lubricating oil and grease.

It is a good solvent for Polyacrylonitrile and polyvinyl chloride. It can be used as a spinning fluid for textiles, as a solvent for removing acid gases and as an additive for concrete, as a component and raw material for pharmaceuticals, as a stabilizer for plastic foaming agent and synthetic lubricating oil, and as an excellent solvent for lithium battery electrolyte in battery industry.