Novel synthetic process of p-phenylene dimethyl ether

Abstract

The invention relates to a novel process for synthesizing p-xylene glycol dimethyl ether. The synthesis method takes hydrochinone and dimethyl sulfate as raw materials, and obtains the product through substitution inside an alkaline medium. Moreover, the synthesis method has the technological characteristics that by means of the principle of equilibrium shifting, the product is moved out of a reaction system during reaction, thereby accelerating reaction and ensuring complete reaction; in the prior synthesis process, the auxiliary raw material dimethyl sulfate no longer participates in reaction when reacted to generate monomethyl sodium sulfate, and the theoretical utilization rate of dimethyl sulfate is only 50 percent; therefore, the method greatly increases the utilization rate of dimethyl sulfate, and reduces the consumption of dimethyl sulfate by 40 percent; meanwhile, reaction yield is also increased to a certain extent; moreover, because the process makes use of the special characteristics of azeotropic distillation of the product and water, the product obtained during reaction can be moved out in time, while the reaction raw materials and intermediate product para hydroxyanisole are stored in a reactor in the form of sodium salts in the alkaline medium and do not enter the product when distilled out along with water vapor; therefore, the product has extremely high purity and can be obtained without adopting the prior alcohol refining; and the novel process ensures greatly simplified production process, higher production safety, lower production cost and labor intensity and better operating environment for workers, thereby having significant social benefit and economic benefit.

Description

technical field [0001] The invention relates to a new process for synthesizing p-xylylene dimethyl ether. More specifically, it uses the principle of equilibrium movement to move the product out of the reaction system at the same time as the reaction. While speeding up the reaction and improving the utilization rate and yield of raw materials, the cumbersome post-treatment and refining process in the original process is reduced, and high-quality products are obtained. P-Phenylene Dimethyl Ether Products. Background technique [0002] P-xylylene dimethyl ether is also known as 1,4-xylylene dimethyl ether, p-dimethoxybenzene, hydroquinone dimethyl ether and hydroquinone dimethyl ether, etc. Its molecular formula is: C 8 h 10 o 2 , Molecular weight: 138.17, with aromatic smell, is a relatively common organic synthetic raw material, often used in the synthesis and preparation of spices, daily chemicals, food, tobacco flavors, etc., and can also be used as an anti-wind erosion...

AI Technical Summary

Problems solved by technology

[0003] At present, the product mainly has two synthesis routes of methylation of dimethyl sulfate under normal pressure and pressure methylation of methyl halide. The route of methylation of dimethyl sulfate under normal pressure uses hydroquinone as the starting material It is obtained by forming a salt with a strong base in an alkaline medium and then replacing it with dimethyl sulfate. The process yield is high, the product quality is stable, and the reaction conditions are mild. However, the raw material dimethyl sulfate is a highly toxic product, and the price is relatively high. High, and the utilization rate of the methyl group in dimethyl sulfate is only 50%, the remaining methyl group after generating monomethyl sulfate sodium salt no longer participates in the reaction, so the unit consumption of dimethyl sulfate is higher, which not only increases production cost, and increased the difficulty of wastewater treatment; due to the cost of raw materials, haloalkane used in the pressurized methylation process of halomethane is cheap and easy-to-get monochloromethane, and hydroquinone in a strong alkaline medium under pressure The raw material monochloromethane used in this process is cheap, but the reaction needs to be carried out under pressure, the equipment investment is high, and the reaction yield is low, and the total production cost is still high; the above two processes all have a common The disadvantage is that there are still some monomethylated products p-hydroxyanisole in the product, and it needs to be further refined to obtain high-content p-phenylenedimethyl ether finished product

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