CAS number：107-21-1
molecular formula：C2H6O2
molecular weight：62.07
EINECS number：203-473-3

English synonyms

2-Hydroxyethanol;Aliphatic diol;Athylenglykol;Dihydroxyethane;dowtherm;Dowtherm SR 1;dowthermsr1;ethane-1,

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Introduction

Ethylene glycol, also known as glycol, is the simplest aliphatic dihydric alcohol. It has the chemical properties of alcohols, such as being able to generate ethers and esters, can be oxidized to generate aldehydes or acids, and can be condensed to generate ethers. Can also be substituted by halogen. Reaction with acid chloride or acid anhydride generally forms diester. Heating under the action of a catalyst (manganese dioxide, aluminum oxide, zinc oxide or sulfuric acid) can dehydrate intramolecularly or intermolecularly to generate cyclic ethylene glycol acetal, which reacts with nitric acid to generate ethylene glycol dinitrate ( a type of explosive). Ethylene glycol is a raw material for the production of polyester resin, alkyd resin, and polyester fiber. It is also used as an antifreeze agent for automobiles and a refrigerant for aircraft engines. Ester consumption is equal. In addition, polymer compounds such as polyester fibers can also be synthesized. The combination of ethylene glycol dinitrate and nitroglycerin can lower the freezing point of explosives. Ethylene glycol can also be used as a raw material and high boiling point solvent for medicines and plastics. In industry, ethylene is used as a raw material, which is first converted into ethylene oxide and then hydrolyzed to produce ethylene glycol.

 Chemical properties

 Colorless transparent viscous liquid, sweet and hygroscopic. Miscible with water, lower aliphatic alcohols, glycerin, acetic acid, acetone and similar ketones, aldehydes, pyridine and similar coal tar bases, slightly soluble in ether, almost insoluble in benzene and its homologues, chlorinated hydrocarbons, Petroleum ether and oils.

Use

●  Mainly used in the production of polyester resins, alkyd resins, plasticizers, antifreeze agents, also used in cosmetics and explosives

●  Used as analytical reagent, chromatographic analysis reagent and capacitor medium

●  Ethylene glycol is an intermediate of the fungicides penconazole and hymexazol.

●  Ethylene glycol is mainly used to prepare antifreeze agents for automobile cooling systems and to produce polyethylene terephthalate (the raw material for polyester fibers and polyester plastics). It can also be used to produce other synthetic resins, solvents, lubricants, Surfactants, softeners, moisturizers, explosives, etc. Ethylene glycol can often be used instead of glycerin, and is used as a hydrating agent and a solvent in the tanning and pharmaceutical industries, respectively. Ethylene glycol has a strong dissolving ability, but it is easily metabolized and oxidized to produce toxic oxalic acid, so it cannot be widely used as a solvent. Adding ethylene glycol to the hydraulic fluid can prevent the oil-based hydraulic fluid from eroding the rubber in the system; the water-based hydraulic fluid with ethylene glycol as the main component is a non-combustible hydraulic fluid, which is used in aircrafts and automobiles And high-temperature molding presses. Ethylene glycol has many important derivatives. Low molecular weight polyethylene glycol (ethylene glycol, diethylene glycol, triethylene glycol or respectively diethylene glycol, triethylene glycol, tetraethylene glycol) is actually obtained by hydration of ethylene oxide. Diol by-products. Diethylene glycol can be used as a wetting agent, plasticizer, sizing agent, printing ink solvent, natural gas dehydration desiccant and aromatic hydrocarbon extraction solvent. Diethylene glycol dinitrate is similar to ethylene glycol dinitrate and is also an important industrial explosive. High-molecular-weight polyethylene glycols are also useful derivatives, ranging from colorless transparent viscous liquids to waxy solids according to different molecular weights. It is used as a lubricant, moisture retaining agent, solvent, intermediate in rubber and food industries, and also used in the preparation of cosmetics and auxiliary agents in the fields of textiles and papermaking. There are many kinds of esters of ethylene glycol, which are widely used as solvents. Ethylene glycol esters of long-chain fatty acids have surface-improving properties and can be used alone or together with surfactants as emulsifiers, stabilizers, dispersants, wetting agents, foaming agents, and suspending agents. Ethylene glycol reacts with urea to form ethylene urea, which is used in the textile industry. Disodium ethylene glycol reacts with 1,2-dibromoethane to form dioxane, which is a special solvent. Different oxidizing agents or reaction conditions are used for ethylene glycol. After oxidation, glycolaldehyde, glyoxal, glycolic acid, oxalic acid, etc. can be obtained.

●  Mainly used in the production of synthetic resins, surfactants and explosives, also used as antifreeze

●  Gas chromatographic stationary liquid (maximum operating temperature 50°C, solvent chloroform), separation and analysis of low-boiling point oxygen-containing compounds, amine compounds, nitrogen or oxygen heterocyclic compounds. Determination of calcium oxide, solvents, antifreeze in cement, manufacture of polyester resins, plasticizers, cosmetics, explosives, cold-resistant lubricants, surfactants, varnishes, dyes, inks, etc., organic synthesis.

Production method

●  1. Direct hydration of ethylene oxide is currently the only method for producing ethylene glycol on an industrial scale. Under the condition of pressurized (2.23MPa) and 190-200℃, ethylene oxide and water are directly hydrated in the liquid phase in a tubular reactor to produce ethylene glycol, and diethylene glycol and diethylene glycol are by-products at the same time. Ethylene glycol and polycondensed polyethylene glycol. The dilute ethylene glycol solution obtained from the reaction is concentrated by a thin-film evaporator, and then dehydrated and refined to obtain qualified ethylene glycol products and by-products. 2. Sulfuric acid catalyzed hydration of ethylene oxide Ethylene oxide and water are hydrated under the catalysis of sulfuric acid at 60-80°C and 9.806-19.61kPa to form ethylene glycol. The reaction solution is neutralized with liquid caustic soda, and the water is evaporated by the evaporator to obtain 80% ethylene glycol, which is then rectified and concentrated in the rectification tower to obtain more than 98% of the finished product. This method is a method developed in the early stage. Due to the problems of corrosion, pollution and product quality, and the complexity of the refining process, countries have gradually stopped using it and switched to the direct hydration method. 3. Ethylene direct hydration method directly synthesizes ethylene glycol from ethylene without ethylene oxide. 4. Dichloroethane hydrolysis method. 5. Formaldehyde method.

●  The preparation of ethylene glycol adopts chlorohydrin method, ethylene oxide hydration method and ethylene direct hydration method in industry. Each method has its own characteristics, which are described as follows.
Chlorohydrin method
It is obtained by hydrolyzing chlorohydrin as a raw material in an alkaline medium. The reaction is carried out at 100°C. First, ethylene oxide is generated, and then ethylene glycol is generated by pressurized hydrolysis under a pressure of 1.01 MPa.
Ethylene oxide hydration
The ethylene oxide hydration method includes catalytic hydration method and direct hydration method, and the hydration process can be carried out under normal pressure or under pressure. Atmospheric pressure hydration generally uses a small amount of inorganic acid as a catalyst and reacts at 50-70°C.
The molar ratio of ethylene oxide to water in the pressurized hydration method should be higher, more than 1:6, to reduce the side reaction of ether formation. The temperature of the reaction is 150°C, and the pressure is 147kPa. Hydrate to obtain ethylene glycol.
At present, there is a gas-phase catalytic hydration method, which uses silver oxide as a catalyst and alumina as a carrier, and reacts at 150-240 ° C to generate ethylene glycol.
Ethylene direct hydration
Ethylene is oxidized in acetic acid solution in the presence of a catalyst (such as antimony oxide TeO2, palladium catalyst) to generate monoacetate or diacetate, and further hydrolyzed to obtain ethylene glycol.
The ethylene oxide hydration method is better in the above several methods, the process is simple, and it is suitable for industrialization.

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