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Method for testing pyromellitic acid anhydride purity and organic impurity

A technology of pyromellitic dianhydride and organic impurities, which is applied in the detection field of pyromellitic dianhydride purity and organic impurities, can solve the problems of meaningless data, no PMDA testing standard, and inability to accurately determine the purity, etc. Achieve the effect of easy operation

Active Publication Date: 2008-08-27
常熟华虞环境科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] 2. Liquid chromatography can be done by domestic research institutes and colleges and universities, but there is no detection specification for PMDA, and each has its own method. It is basically possible to measure the purity of PMDA alone, but the analysis of trace organic impurities is helpless
[0020] The above-mentioned various detection methods can only roughly detect the purity of the product, such as the determination of melting point, only pure substances have corresponding melting points, and the melting points of substances containing trace impurities can only be relatively compared and cannot be accurately determined purity
Then there is chemical titration, the error of which is allowed to be 1-3%, and if the purity of the substance to be measured has reached more than 99%, the data of chemical titration is meaningless

Method used

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  • Method for testing pyromellitic acid anhydride purity and organic impurity
  • Method for testing pyromellitic acid anhydride purity and organic impurity
  • Method for testing pyromellitic acid anhydride purity and organic impurity

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Experimental program
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Effect test

Embodiment 1

[0040] A) ethyl esterification reaction, accurately weigh the refined PMDA sample of 0.100g, place in the 100ml single hole round bottom flask, add 5ml with Na without water of crystallization 2 CO 3 After the dehydration treatment, connect the condenser to the flask, and reflux at 78°C for 35 minutes to completely esterify the ethyl ester. Transfer the product after the ethyl esterification reaction together with the excess ethanol to a glass watch glass and move it into a vacuum drying oven for slow drying. The excess ethanol was removed by slow evaporation to obtain a white powdery crystalline solid;

[0041]B) Methyl esterification reaction, weigh 23 mg of ethyl esterified crystals obtained by step A) and place in a 5ml esterification bottle, add excess diazomethane saturated ether solution to carry out methyl esterification reaction in the esterification bottle , until no bubbles are produced and the solution is light yellow, the methyl esterification reaction is over, a...

Embodiment 2

[0043] Only change the amount of the refined PMDA sample into 0.098g in the step A), add Na 2 CO 3 Change the absolute ethanol after dehydration to 6ml, change the reflux temperature to 79°C, and change the reflux time to 40min; change the amount of ethyl esterified crystals in step B) to 20mg, and change the temperature of the constant temperature water bath for evaporation to remove ether Change to 55°C, use a pipette to transfer the volume of chromatographically pure chloroform (diluent) to 0.5ml, and change the gas chromatography injection volume to 0.2μl. All the other are with embodiment 1.

Embodiment 3

[0045] Only change the amount of the refined PMDA sample into 0.095g by weighing, add Na with no water of crystallization 2 CO 3 Change the absolute ethanol after dehydration to 5.5ml, change the reflux temperature to 80°C, and change the reflux time to 30min; change the amount of ethyl esterified crystals in step B) to 30mg, and change the constant temperature water bath that evaporates and removes ether The temperature was changed to 65° C., the volume of chromatographically pure chloroform (diluent) pipetted with a pipette was changed to 0.9 ml, and the gas chromatography injection volume was changed to 0.4 μl. All the other are with embodiment 1.

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Abstract

The invention provides a test method for the purity of pyromellitic dianhydride and organic impurities, which is used to test the purity of PMDA products obtained after crude products of pyromellitic dianhydride are refined and organic impurities contained in the PMDA products; the method includes the preparation of color spectrum injection samples and the analysis of the chromatograph, wherein the preparation of color spectrum injection samples includes the following steps of an ethyl esterifying reaction step and a methyl esterifying reaction step; the ethyl esterifying reaction step is that pyromellitic dianhydride samples are weighed in a container, and ethanol is added for the ethyl esterifying reaction under a counterflow condition, after the reaction is ended, products together with the redundant ethanol are transferred in a watch glass, and the watch glass is transferred in a vacuum drying oven for removing the redundant ethanol, in the end, the ethyl esterifying crystals are obtained; the methyl esterifying reaction step is that the ethyl esterifying crystals are put in an esterifying container, and diazomethane ether saturated solution is added for the methyl esterifying reaction, the redundant ether is removed by steaming after the methyl esterifying reaction is ended, and the samples for the gas chromatographic analysis are obtained, and then samples for the gas chromatographic analysis are diluted by a thinning agent, here the color spectrum injection samples are obtained, and the color spectrum injection samples are sent to the chromatograph for analyzing the purity and organic impurities. The test method has the advantages of simple operation and quick and accurate detection of the purity and organic impurities of the pyromellitic dianhydride (PMDA).

Description

technical field [0001] The invention relates to a method for detecting the purity of pyromellitic dianhydride and organic impurities, which is used for detecting the purity and contained organic impurities of PMDA products refined from crude pyromellitic dianhydride (PMDA for short). Determination. Background technique [0002] Since pyromellitic dianhydride is a product developed in recent years for the preparation of new materials, due to its large molecular weight (218.12) and high boiling point (398°C), it is difficult or even impossible to detect it by conventional analysis methods. trace organic impurities. The organic impurities referred to here mainly include: trimellitic anhydride (Trimellitic Anhydride, TMA for short), pyromellitic acid (Pyromellitic Acid, PMA for short), pyromellitic monoanhydride (Pyromellitic Mono Anhydride, PMMA for short), 5-methyl meta Triacid (5-Methyltrimellitic Acid, abbreviated to MTMA). For the detection of these organic impurities, a...

Claims

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Application Information

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IPC IPC(8): G01N30/00G01N1/28
Inventor 刘忠云陈丽萍赵海峰王玉山袁珉虹柏彩萍陈燕丹
Owner 常熟华虞环境科技有限公司
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