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Method for purifying ortho-toluene diamine

A technology of o-toluenediamine and a purification method, which is applied in the field of purification of o-toluenediamine, can solve the problems of not being able to significantly reduce the content of green impurities, and achieve the effects of improving competitiveness, simplifying the process, and reducing production costs

Inactive Publication Date: 2006-04-05
SHANGHAI TAIHE INT TRADE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although when the raw material processed in this way is used to prepare the sodium tolyltriazole product, the color of the product will be slightly improved, but it still cannot significantly reduce the content of green impurities

Method used

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  • Method for purifying ortho-toluene diamine
  • Method for purifying ortho-toluene diamine
  • Method for purifying ortho-toluene diamine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] In a 500 ml three-necked flask equipped with a rectifying column with a plate number of 20-22 and a thermometer, add 400 grams of o-toluenediamine raw material (purchased from Cangzhou Dahua Group Co., Ltd., the purity measured by the internal standard method is 85.5 % by weight) and 0.4 gram of zinc carbonate, carry out vacuum distillation. The reflux ratio at the beginning was adjusted to about 10:1, and when the liquid temperature was heated to 150-155°C, the fore fraction at 76-118°C / 650-800Pa was collected, totaling 3.4 grams. Then the reflux ratio was adjusted to about 5:1. Under the same liquid temperature conditions, the o-toluenediamine fraction at 118-120° C. / 650-800 Pa was collected, totaling 390.5 grams, and the residue at the bottom of the bottle was 5.5 grams. The purity of the obtained o-toluenediamine fraction was 99.6% (determined by normalization method).

Embodiment 2

[0034]In the 500 milliliters of three-necked flasks that the rectifying tower that is 20-22 plate numbers, thermometer and nitrogen inlet pipe are equipped with, add 400 gram o-toluenediamine raw materials (the purity that internal standard method measures is 85.5% by weight) and 0.2 gram basic zinc carbonate, nitrogen gas and vacuum distillation. The reflux ratio at the beginning was adjusted to about 10:1, and when the liquid temperature was heated to 150-155°C, the fore fraction at 76-118°C / 650-800Pa was collected, totaling 3.4 grams. Then the reflux ratio was adjusted to about 5:1. Under the same liquid temperature conditions, the o-toluenediamine fraction at 118-120° C. / 650-800 Pa was collected, totaling 390.3 grams, and the residue at the bottom of the bottle was 5.5 grams. The purity of the obtained o-toluenediamine fraction was 99.5% (determined by normalization method).

Embodiment 3

[0036] In the 500 milliliters three-neck flask that the rectifying tower that is 20-22 plate numbers, thermometer and nitrogen inlet pipe are equipped with, add 400 gram o-toluenediamine raw materials (the purity that internal standard method measures is 85.5% weight) and 0.4 gram of zinc sulfate, nitrogen gas was introduced, and vacuum distillation was carried out. The reflux ratio at the beginning was adjusted to about 10:1, and when the liquid temperature was heated to 150-155°C, the fore fraction at 76-118°C / 650-800Pa was collected, totaling 3.4 grams. Then adjust the reflux ratio to about 5:1, and collect 118-120° C. / 650-800 Pa of o-toluenediamine fractions under the same liquid temperature conditions, a total of 390.0 grams. The purity of the obtained o-toluenediamine fraction was 99.3% (determined by normalization method).

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Abstract

A process for purifying O-toluene diamine includes adding the salt of Zn, Fe, Mg or Cr (0.05-0.5 wt.%) and vacuum rectifying.

Description

technical field [0001] The present invention relates to a method for purifying o-toluenediamine, in particular to an improved rectification method for extracting o-toluenediamine from the by-product of producing toluene diisocyanate. technical background [0002] Toluene diisocyanate is a useful intermediate for the production of polyurethanes with a wide range of uses. It is usually dinitrated from toluene to generate m-dinitrotoluene and a small amount of o-dinitrotoluene, which are reduced to m-toluene diamine (4-methyl -1,3-phenylenediamine and 2-methyl-1,3-phenylenediamine mixture) and o-toluenediamine (3-methyl-1,2-phenylenediamine and 4-methyl-1, 2-Phenylenediamine mixture), m-toluenediamine and o-toluenediamine can be separated by rectification. m-Toluenediamine reacts with phosgene to form toluene diisocyanate, which is used in the preparation of polyurethanes. However, significant quantities of o-toluenediamine by-products (eg, millions of pounds per year in the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C211/50C07C209/84
Inventor 马纯俊李建高田晓宏
Owner SHANGHAI TAIHE INT TRADE CO LTD