Tetraacetylethylenediamine (TAED) recrystallization method

A technology for crude tetraacetylethylenediamine and tetraacetylethylenediamine, which is applied in the separation/purification of carboxylic acid amides, organic chemistry, etc., can solve the problems of TAED hydrolysis and high toxicity, affecting product quality, low solubility, etc. Fast, easy recycling, high solubility

Inactive Publication Date: 2013-12-04
ZHEJIANG UNIV
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AI Technical Summary

Problems solved by technology

Due to the gradual accumulation of trace pigments that may be brought into raw materials used in industrial production and pigments that may be produced during the reaction process, the amount of pigments in the reaction system will continue to increase with the prolongation of the reaction cycle, and finally make the later products Due to the failure of conventional decolorization, the product has a certain degree of color, which affects the quality of the product, especially the product that is recovered from the mother liquor after terminating a cycle contains a large amount of pigment, which must be reprocessed before it can be recycled.
The general recycling method is to recrystallize with different benzene solvents (such as benzene, toluene, ethylbenzene, xylene or chlorobenzene, etc., a mixed solvent of one or more organic solvents) after washing with water. TAED has the disadvantages of high hydrolysis and toxicity, and low solubility

Method used

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  • Tetraacetylethylenediamine (TAED) recrystallization method
  • Tetraacetylethylenediamine (TAED) recrystallization method
  • Tetraacetylethylenediamine (TAED) recrystallization method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Hydroalcohol Concentration Selection:

[0021] Weigh four samples of about 1.0 g after washing, use 95%, 80%, 70%, and 60% of 10 times the amount of ethanol respectively, heat and reflux in a water bath at about 75°C for 25 minutes to completely dissolve the sample, take it out and let it cool and place it Complete crystallization in the refrigerator, filter, dry and weigh. Then weigh about 0.5 g of each sample obtained from the first recrystallization, and carry out the second recrystallization in the same way. See Table 1 for the corresponding conditions, results and precautions.

[0022] Table 1 Experimental results of water-containing alcohol concentration selection

[0023]

[0024]

Embodiment 2

[0025] Embodiment 2 mixed solvent proportioning test

[0026] According to the method of Example 1, the recrystallization test was carried out by mixing two solvents of dichloromethane and 80% ethanol, and the solvent ratios were (1:9), (2:8), (3:7), (4:6) ), the solvent consumption is 10 times, the operation steps are the same as above, and the results are shown in Table 2.

[0027] Table 2 dichloromethane and 80% ethanol mixed solvent proportioning test result

[0028]

Embodiment 3

[0029] The selection of ethanol concentration during mixed solvent recrystallization of embodiment 3

[0030] In view of the fact that 95% ethanol is relatively poor to the recrystallization decolorization effect of TAED in embodiment 1, the recrystallization yield of 70% ethanol is lower to TAED, and the mixed solvent recrystallization decolorization effect of embodiment 2 is better, so on this basis in In the range of 70% to 95%, the ethanol concentration is adjusted and selected again, that is, four concentration gradients of 90%, 85%, 80%, and 75% are selected to carry out the recrystallization experiment. The mixed solvent is composed of dichloromethane and water-containing alcohol in a ratio of (3:7), the amount of solvent is 10 times, the temperature of the water bath is 60 ° C (it can be boiled and quickly dissolved), the operation method is the same as above, and the results are shown in Table 3.

[0031] Table 3 The influence of ethanol concentration on the recrystal...

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Abstract

The invention provides a tetraacetylethylenediamine (TAED) recrystallization method, wherein the effective recrystallization is carried out by adopting a crude TAED product washed with water or water-containing alcohol or other solvents and selecting a mixed solvent of halogenated varsol and water-containing alcohol with different concentrations. The method has the advantages that the mixed solvent has low boiling point, has high solubility and fast solution speed for crude the TAED product mixed with pigments, refluxes directly or under the condition of stirring, and has faster speed and complete effect on cooling crystallization, crystals are good in graininess, crystallized pigments are quantitatively detected and controlled, the solvent is easy for recycling, and the like, and in addition, the requirements for equipment are simple, the investment is low and the cycle is short.

Description

technical field [0001] The invention belongs to the technical field of production of purified products, and relates to a method for recrystallizing crude tetraacetylethylenediamine (TAED). Background technique [0002] Tetraacetylethylenediamine (TAED) is a bleach activator commonly added to laundry detergents that can adapt to low-temperature bleaching. Due to the gradual accumulation of trace pigments that may be brought into raw materials used in industrial production and pigments that may be produced during the reaction process, the amount of pigments in the reaction system increases continuously with the prolongation of the reaction cycle, and finally makes the later products Because conventional decolorization does not work well, the product has a certain degree of color, which affects product quality, especially the product that is recovered from the mother liquor after terminating a cycle has a large amount of pigment, and must be reprocessed before recycling. The g...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C233/91C07C231/24
Inventor 徐娟华左文松
Owner ZHEJIANG UNIV
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