Method for preparing epoxide by halogen-alcohol method

Abstract

A method for preparing epoxide by a halogen-alcohol method comprises the following steps: (1) halogenation-alcoholization: adding H2O, halogen elementary substance (optimally selecting chlorine, bromine or iodine) and an olefinic unsaturated compound or olefin compound which contains one or multiple C=C double bonds into a reaction device, and carrying out halogenation-alcoholization reaction to obtain halogenohydrin; (2) saponification: carrying out saponification reaction on the halogenohydrin obtained in the step (1) and hydroxide of an alkali metal, and separating to obtain the epoxide and halogenated alkali metal salt; (3) electrodialysis: carrying out bipolar membrane electrodialysis on the halogenated alkali metal salt obtained in the step (2), thus obtaining the hydroxide of the alkali metal and halogen hydride. The method provided by the invention has the characteristics that the method can be used for preparing the epoxide with extremely high selectivity and yield, and the discharge of wastewater and waste residues is reduced greatly.

Description

technical field [0001] The invention relates to a method for preparing epoxides; more specifically, it provides a method for preparing epoxides by using olefins as raw materials and adopting a halohydrin method. Background technique [0002] Epoxides contain epoxy groups, are chemically active, and are easy to ring-opening polymerization. They are important organic chemical raw materials. For example, propylene oxide, as the third largest derivative of propylene series, is most widely used in the preparation of polyether polyols, as well as in the production of propylene glycol and nonionic surfactants. In recent years, PO is also widely used in the synthesis of green products such as dimethyl carbonate and carbon dioxide polymer. [0003] The main industrial methods for the production of propylene oxide are chloroalcoholization and co-oxidation, and the co-oxidation is further divided into ethylbenzene co-oxidation and isobutane co-oxidation. Most enterprises in my countr...

AI Technical Summary

Problems solved by technology

[0007] The chlorohydrin method of prior art prepares epoxide mainly to have the following problems: 1. chlorine gas passes into water, and reaction is extremely slow and solubility is very little, and the reaction of chlorine gas and water is reversible reaction, causes the hypochlorous acid ratio that reaction generates is very little, As a result, the yield of the haloalcoholation reaction is very low, generally only 3-4%

③The reaction produces a large amount of calcium chloride, which leads to high COD of wastewater and pollutes the environment

⑤④ The disadvantage of the chlorohydrin method is that it consumes a lot of water resources and produces a large amount of waste water and waste residue. The chlorohydrin method produces 1t of epoxides and produces 40-50t of chloride-containing waste water and 2.1t of calcium chloride waste residue. The waste water has high temperature and pH The "five highs" characteristics of high value, high chlorine content, high COD content and high suspended solids content are difficult to handle and seriously pollute the environment

However, such methods have the inherent problems of the chlorohydrin method

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