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Purification method of technical grade dimethoxym ethane

A purification method, methylal technology, applied in the field of industrial-grade methylal purification, can solve the problems of high content, huge equipment, and the need for a large amount of nitrogen to regenerate the extraction agent, and achieve the effect of simple process and convenient operation

Inactive Publication Date: 2008-11-12
NANJING FORESTRY UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the toxic and harmful factors of methanol, the scope of application of industrial-grade methylal in daily chemical, pharmaceutical, electronic cleaning, polymer preparation and other fields is greatly limited; in order to obtain high-purity methylal, it needs to be refined.
[0005] The commonly used purification method adopts the zeolite molecular sieve adsorption method to absorb impurities such as water and methanol, but the industrial grade methylal products contain high impurities such as water and methanol, so a large amount of molecular sieves are required, the equipment is huge, the regeneration requirements are high, and the labor intensity is high. Inconvenient to operate
[0006] Chinese patent CN95195524.1 adopts polyethylene glycol or polyethylene glycol dimethyl ether as a high-boiling point extraction solvent, and removes methanol and water in methylal by means of pressurized extraction and rectification, and 98.3% of methylal can be removed Increase the content to 99.5%, the effect is better, but the equipment requirements are high, and the regeneration of the extraction agent requires a large amount of nitrogen
This type of extraction and rectification of methylal requires gas-phase feed, heating of the extractant to feed, continuous countercurrent operation, and high requirements for operators and equipment.

Method used

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  • Purification method of technical grade dimethoxym ethane

Examples

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Comparison scheme
Effect test

example 1

[0024] Add 570g of methylal (0.3% of water, 4.0% of methanol) and 170g of polyethylene glycol dimethyl ether into a 1000ml three-necked flask equipped with a φ20×1000 packed tower and a rectifying head, heat up, and operate under total reflux to the tower The top is stable at 42°C, the temperature of the tower bottom is stable at 48°C, and the reflux ratio is adjusted to 4:1. First collect the former fraction with a top temperature lower than 42°C, and then collect the methylal fraction at 42-42.5°C. When the kettle temperature starts to rise , increase the reflux ratio to 6:1, until the temperature of the kettle rises to 60°C, collect 459g of the methylal product, and analyze the purity of the methylal by gas chromatography to 99.02%; After mixing 80g of dimethyl ether, add it to a 1000ml three-necked flask with a φ20×1000 packed tower and a rectifying head, heat up, and operate the total reflux until the top of the tower is stable at 42°C, the temperature of the bottom of the...

example 2

[0026] The used polyethylene glycol dimethyl ether is regenerated on a rectification tower with φ20×600 packing, and the methylal entrained in the polyethylene glycol dimethyl ether is first steamed under normal pressure, and the top temperature is controlled to be less than 43°C, and the reflux ratio 3:1, collect methylal, the purity is 95.8%; then control the top temperature at 64-65°C, the reflux ratio is 3:1, collect the methanol fraction, the purity is 96.3%; increase the temperature of the kettle to 130°C, collect the residual methanol and water , and slowly switch to a vacuum of -0.09MPa to remove trace impurities in polyethylene glycol dimethyl ether.

[0027] Add 570g of methylal (0.3% of water, 4.0% of methanol) and 170g of regenerated polyethylene glycol dimethyl ether into a 1000ml three-necked flask equipped with a φ20×1000 packed tower and a rectifying head, heat up and operate under full reflux Until the top of the tower is stable at 42°C, the temperature of the...

example 3

[0029] In the 2m with φ300×10000 packed tower 3Add 1100kg of methylal (0.2% of water content, 4.7% of methanol) and 300kg of polyethylene glycol dimethyl ether into the rectification kettle respectively, heat up and operate the total reflux until the top of the tower is stable at 42°C, and the temperature of the tower bottom is stable at 48°C , adjust the reflux ratio to 4:1, first collect the front fraction whose top temperature is less than 42°C, then collect the methylal fraction at 42-42.5°C, when the kettle temperature starts to rise, increase the reflux ratio to 6:1, to the kettle temperature When the temperature rises to 60°C, 913kg of methylal product is collected, and the purity of methylal is 89.9% according to gas chromatography analysis; then 910kg of methylal with a content of 89.9% and 270kg of polyethylene glycol dimethyl ether are mixed and added to a φ300×10000 packed tower 2m 3 In the rectification kettle, heat up the temperature, operate the total reflux un...

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Abstract

The invention discloses a purification method for industrial methylal and is characterized in that: polyethylene glycol dimethyl ether is taken as solvent, is mixed with the industrial methylal, and then is added into a distillation tower for normal pressure rectification, and methylal fractions are collected under a tower top temperature of between 42 and 42.5 DEG C; and the rectification is repeatedly subject to the purified methylal fractions to produce the high-purity methylal. The purification method has simple process and convenient operation; and the purity of the methylal can reach 99.9 percent.

Description

Technical field: [0001] The invention relates to a method for purifying industrial-grade methylal. The chemical name of methylal is 1,2-dimethoxymethane, and its structural formula is: CH 3 OCH 2 OCH 3 . It belongs to the field of organic chemical technology. Background technique: [0002] Methylal is a colorless transparent liquid with a smell similar to chloroform; boiling point is 42.3°C, melting point is -104.8°C, flash point is -17.8°C, and spontaneous ignition point is 237°C; it is relatively stable to alkali and is easily decomposed into formaldehyde and methanol. At 16°C, it dissolves 32.3% (Wt) in water and 4.3% (Wt) in methylal. The azeotropic mixture with methanol can dissolve nitrocellulose with high nitrogen content; it is miscible with alcohol, ether, acetone, etc., and can dissolve resins and oils, and its solubility is stronger than that of ether and acetone. [0003] Methylal is C 1 The refined derivatives of methanol and formaldehyde, the basic chemi...

Claims

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Application Information

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IPC IPC(8): C07C41/58C07C43/30
Inventor 朱新宝王琴袁艳群胡明华
Owner NANJING FORESTRY UNIV
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