Preparation method for halogenohydrin and epoxide

Abstract

The invention provides a preparation method for halogenohydrin and an epoxide. The method comprises the following steps: (1) halogenohydrination: adding H2O2 (or hydrogen peroxide), elemental halogen and an olefinic unsaturated compound with one or more C=C double bonds into a reaction apparatus for halogenohydrination so as to prepare halogenohydrin; (2) saponification: subjecting halogenohydrin prepared in the step (1) and a hydroxide of an alkali metal to saponification and carrying out separation so as to obtain the epoxides and a halogenated alkali metal salt; and (3) electrodialysis: subjecting the halogenated alkali metal salt obtained in the step (2) to bipolar membrane electrodialysis so as to obtain the hydroxide of the alkali metal and halogen hydride. The method has realizes high selectivity and yield in preparation of halogenohydrin or the epoxide, and greatly reduces discharge of waste water and waste residues.

Description

technical field [0001] The present invention relates to a method for preparing halohydrin, and a method for preparing epoxide from halohydrin; more specifically, it provides a method for preparing halohydrin using olefin as a raw material and adopting a new halohydrin method to prepare epoxy compound 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] Propylene oxide production The main industrial methods for producing propylene oxide are chloroalcoholization and co-oxidation, and the co-...

AI Technical Summary

Problems solved by technology

[0008] The preparation of epoxides by the chlorohydrin method of the prior art mainly has the following problems: 1. raw material chlorine and olefins undergo addition side reactions to generate dichloroalkanes

Dichloropropane is difficult to utilize and wastes a lot of raw materials

In addition, chlorine gas reacts with olefins, releasing a large amount of heat, which is concentrated in the reaction vessel, resulting in great production hazards.

②A small amount of oxygen is inevitably entrained in the raw material chlorine gas during the production process. As the reaction proceeds, chlorine gas continuously participates in the reaction, so chlorine gas needs to be continuously replenished, while oxygen cannot participate in the reaction and accumulates in the reaction device continuously. , the oxygen concentration continues to rise, and the reaction releases heat. Oxygen, chlorine, and olefins exist at the same time, and it is easy to cause an explosion at high temperature.

④The reaction produces a large amount of calcium chloride, which leads to high COD of wastewater and pollutes the environment

⑤ 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

⑥ The hypochlorous acid produced in the production process also seriously corrodes the equipment

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