Background and overview[1]
Diethylene glycol, also known as diethylene glycol, is a colorless and transparent slurry liquid. When reacting with acid anhydrides, esters are formed. It reacts with alkyl sulfate or halogenated hydrocarbon to generate ether. It is mainly used as a gas dehydrating agent and extraction agent, and also as a lubricant and finishing agent for textiles. Derived from the interaction of ethylene oxide and ethylene glycol.
Structure
Apply[1]
1. Direct utilization of diethylene glycol
Diethylene glycol is a colorless, odorless, transparent, hygroscopic and viscous liquid. It is easily soluble in water, alcohol, acetone, ether, ethylene glycol and other polar solvents. Its chemical properties are similar to ethylene glycol. Direct utilization can be mainly used as solvents for various purposes, natural gas dehydration desiccant, aromatic hydrocarbon separation extraction agent, textile lubricant, softener, finishing agent, as well as solvents such as nitrocellulose, resin, grease and printing ink, and also used as brakes It is an antifreeze component in liquids and compressor lubricants. It can also be used to prepare cleaning agents and as a dispersing solvent in other daily chemicals such as inks. For example: the water content of natural gas dehydrated with 99% diethylene glycol can be as low as 48 mg/m3; diethylene glycol is used as a BTX extraction solvent in the Eudicus device, with good selectivity and an aromatic hydrocarbon recovery rate of >98%; As a dyeing and finishing auxiliary for textiles, alcohol can improve the transfer of dyes and washing fastness, and enhance the antistatic, water-absorbing and anti-fouling properties of synthetic fibers; diethylene glycol is used as an ink wetting agent, which can improve the fluidity and durability of ink. Viscosity quality, increasing light resistance and long-term storage stability, accelerating the fixation and drying speed of ink on the substrate.
2. Processing and utilization of diethylene glycol
The molecular structure of diethylene glycol contains two functional groups, ether bond and hydroxyl group, which give it unique physical and chemical properties. It can be used to produce a variety of chemical products such as ethers, acids, esters, and amines, and is widely used in petroleum. It is widely used in chemical, rubber, plastic, textile, coating, adhesive, pharmaceutical and other industries.
1) Morpholine: Morpholine (1,4-oxazacyclohexane) is an important organic chemical raw material and chemical intermediate with a wide range of uses. It can be used as rubber additives, textile dyeing and weaving auxiliaries, and pharmaceutical intermediates. body, plastic additives, anti-rust agents, surfactants, optical polishing agents, polyamide foaming agents, water treatment agents, preservatives, etc. In addition, morpholine is also an important organic solvent. Before 1990, my country was completely dependent on imports of morpholine. Subsequently, many domestic scientific research institutes conducted extensive research on its synthesis technology and made great progress. Several industrial units were built to meet the growing demand for morpholine in the domestic market. . In recent years, with the continuous advancement of science and technology, new uses of morpholine have continued to emerge, and the market demand for morpholine has continued to increase.
According to market statistics, my country’s demand for morpholine in 2007 was approximately 15,000 tons. The production of morpholine currently mainly uses diethylene glycol and ammonia as raw materials. Under the action of a catalyst, the ammonolysis and dehydration reactions are completed simultaneously to obtain morpholine products. According to different operating pressures, this technology is divided into three synthesis processes: high-pressure liquid phase method, low-pressure gas phase contact method and normal pressure gas phase method. The high-pressure liquid phase method reacts at a pressure of 6.5 to 22.5MP and requires high-pressure equipment. From a thermodynamic point of view, high pressure is unfavorable to the reaction. The yield of morpholine is low, generally below 49%, and the catalyst is easily pulverized and has a short life. The reaction pressure of the low-pressure vapor-liquid phase contact method is generally in the range of 0.5 to 4.2MPa, and diethylene glycol is in a vapor-liquid mixed phase state.
2) Diethylene glycol ether products: Glycol ether products include monoether and double ether of diethylene glycol. Its main varieties include diethylene glycol mono(bis) methyl ether, diethylene glycol mono(bis) ethyl ether, diethylene glycol mono(bis) butyl ether, etc. The monoether and double ether of diethylene glycol have the characteristics of strong solubility, low volatility, low toxicity, good thermal stability, low freezing point, low viscosity, etc., so they are especially suitable for printing inks, dyes, synthetic resins, nitrocellulose, High-boiling point solvents for ballpoint pen oil, textile printing, coatings, high-solid paints, etc.; organic synthetic solvents and industrial cleaning agents; components of brake oil and hydraulic oil; waterproof additives for automobile and aircraft fuel, etc.
3) Diglyceric acid
Diglycolic acid, also known as diglycolic acid, is a colorless and transparent crystal. Due to the presence of ether bonds in the molecular structure, diglyceric acid not only has the characteristics of general organic dibasic acids, but also has good internal rotation and separation properties.�It has the advantages of good flexibility and is an important fine chemical raw material with a wide range of uses. The diglyceric acid diester compound synthesized from diglycolic acid as raw material is an excellent plasticizer for polyvinyl chloride; the sodium salt of diglycolic acid is an excellent detergent component; it is composed of diglycolic acid, diethylene glycol, phthalic anhydride, styrene, etc. The different grades of unsaturated polyester resin synthesized can be used to make fiberglass products, electrical insulation products, adhesive tapes and putty products respectively, with good performance and use effects; diglyceric acid can also be used as a plant growth promoter, etc.
Preparation[1]
A diethylene glycol purification process, the steps are:
①Dissolution: Add crude 3-4wt% strong alkali and crude 3-4wt% ethyl chloride to crude diethylene glycol, and stir at 100°C for 1.5-2 hours to obtain a liquid;
② Distillation under reduced pressure: Distill the liquid obtained in step ① under reduced pressure, collect the fractions at 150-155°C, and obtain purified diethylene glycol.
Main reference materials
[1] Concise Dictionary of Fine Chemicals
[2] New progress in comprehensive utilization technology of diethylene glycol
