Method for preparing dipropylene glycol methyl ether by means of continuous reaction

Abstract

The invention discloses a method for preparing dipropylene glycol methyl ether by means of continuous reaction. The method includes steps of mixing and preheating 2-methoxy-1-propanol, propylene epoxide and strong-alkali catalysts with one another; then feeding the 2-methoxy-1-propanol, the propylene epoxide and the strong-alkali catalysts into pipeline reactors; carrying out etherification reaction; ultimately collecting the dipropylene glycol methyl ether from reaction products. The dipropylene glycol methyl ether is a target product. The method for preparing the dipropylene glycol methyl ether has the advantages that the continuous etherification reaction is carried out, the method includes simple processes, is few in byproducts and high in production efficiency and is safe and environmentally friendly, and separation can be facilitated; the propylene epoxide conversion rate is 100%, the total content of deep reaction byproducts (including tripropylene glycol monomethyl ether) in the etherification products is lower than 4%, the yield of the dipropylene glycol methyl ether is higher than or equal to 96%, and the content (the sum of isomers) of the dipropylene glycol methyl etheris higher than or equal to 99.8%.

Description

technical field [0001] The invention relates to a preparation method of dipropylene glycol methyl ether. Background technique [0002] Dipropylene glycol methyl ether (DPM) is a colorless, low toxicity viscous liquid with a pleasant mild fragrance. It has hydrophilic and lipophilic dual functional groups in its molecular structure. It is completely miscible with water, and can also be miscible with a large number of organic solvents. It has good solubility for many substances. It is widely used in coatings, cleaning agents, electronic inks, cosmetics, etc. field. In particular, dipropylene glycol methyl ether has low surface tension, moderate evaporation rate, good solubility and coupling ability, and has good application performance in water-based coatings, which can replace the highly toxic diethylene glycol ethyl ether and diethylene glycol Butyl ether. [0003] Dipropylene glycol methyl ether is the product of deep reaction in the production process of propylene glyco...

AI Technical Summary

Problems solved by technology

[0004] Zheng Tiejiang et al. (Chinese patent CN104211584A) used the extracted propylene glycol methyl ether as a raw material, and under the action of a strong basic catalyst, continued to perform intermittent ring-opening addition reaction with propylene oxide in an autoclave to prepare dipropylene glycol methyl ether , the raw material column liquid is mainly 2-methoxyl-1-propanol, followed by deep reaction products such as dipropylene glycol methyl ether and tripropylene glycol methyl ether. The composition is complex. These components are easily mixed with Propylene oxide continues to undergo in-depth reactions, resulting in an increase in by-products and a more complex composition, which is not conducive to further separation, and the product quality is poor and cannot meet the requirements of high-end products; the sodium methoxide catalyst is unstable at high temperatures and has potential safety hazards; at the same time, the preparation method The batch reaction of tank type is adopted, and the efficiency is low

[0005] In the production of propylene glycol methyl ether, there will be two isomers of 1-methoxy-2-propanol (primary ether) and 2-methoxy-1-propanol (secondary ether). The composition ratio is about 92:8. Among them, primary ether has low toxicity, good performance, safety and environmental protection, and has a large market demand. Due to factors such as high toxicity and poor performance, secondary ether is often restricted in application, resulting in a backlog of inventory and affecting The production and sales of primary ethers can only be sold at a low price, and the benefits are poor