SU380635A1 - METHOD OF CLEANING AND EXTRACT OF SALT ADIPINIC ACID AND HEXAMETHYLENEDIAMINE - Google Patents

Description

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This invention relates to a process for the preparation of a neutral salt of adipic acid and hexamethylenediamine (AH salt), which is a monomer for the preparation of a polymer and an anide hair (nylon 66).

To obtain anide polymer, a 50-60% aqueous solution of AH salt is usually used, obtained by displacing aqueous solutions of equimolecular amounts of adinic acid (AA) and hexamethylbindiamia (HMD), or by dissolving solid salt, and AG in water. Salt AG, intended for fiber production, must be exceptionally pure. One of the most common impurities in the AH salt from the point of view of fiber production is the admixture of 1,2-diaminocyclohexane (DACG), which is formed as a by-product of the hydrogenation of adipodinitrile in HMD and entering into salt AG together with HMD. The admixture of DACG in the AH salt imparts a color to its solutions, which rapidly increases temporarily and adversely affects the fiber production process and the quality of the finished fiber. The impurity DACG is not removed from the solutions of the salt of LH nr, their treatment with activated carbon. According to the technical specifications of foreign firms producing salt A D for the production of cord and textile fibers, the amount of the mixture indicated in the finished product exceeds 0.002%. The methanol method of obtaining the salt of AG used in the domestic industry does not make it possible to obtain a product suitable for producing good fiber.

A method for isolating the AH salt by spray drying is known. However, this method makes it unacceptable for large-scale production. In addition, the complexity of the design and insufficient degree of extraction of salt AG is noted.

The proposed method for the purification and isolation of salt A g from aqueous solutions is as follows.

The initial solution consists of a solution of the salt AH, PO: to the downstream purification and separation, or from the mother liquor returned to the cycle and the washing water. The resulting solution is heated (in an atmosphere of an inert gas or air) at a temperature not higher than 70-80 ° C, since a further increase in temperature results in a product with a color index above the permissible value. Next, the solution is evaporated (at a pressure above atmospheric), and the evaporation rate should be not more than 85%, since a large degree of upacne will not allow to obtain high-quality product on the content of impurities, including f 2-diamino-cyclohexane. Then the solution is cooled to a temperature not lower than 20 ° C, because crystallization at lower

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temperature pr. leads to the formation of a hydrate form of crystals of sol. and AG, which increases the possibility of increasing impurities from the mother liquor.

The obtained crystals are separated by filtration and washed with -sup1, with an external temperature of filtration with a solution of AG salt, the mother liquor is returned to the crystallization cycle, the washing water, if necessary and repeated washing, is used many times as a washing solution losses. The solution after the 1st stage of washing is mixed with the mother liquor. Mother and rinsing: solutions, when returned to crystallization in the case of the need, are treated with active and dry coal or other sorbite for clarification (under static or diamide conditions). According to the proposed method, high quality AG salts are obtained (with DACG content not exceeding 0.002-0.0025% and color index not exceeding 8-10 units of ARPA), regardless of the content of DACG in the initial solution to be crystallized (and, for example, up to 2% or more ), and regardless of the color index of the initial solution, for example, above 100 units of ARN. In addition, the method is used to purify and isolate the AH salt both from aqueous solutions of O: B and to purify the solid salt of AH obtained by any other method, for example, methanol.

The method of purification and precipitation of solar AH by crystallization can be carried out both periodically and by means of distillation according to the principle of ordinary crystallization and vacuum crystallization.

Example 1. 1.0 kg of a 50% solution of Sol AH, containing 1.1% DACG and having a color index of 64.0, is evaporated in a nitrogen atmosphere at a residual pressure of 233– 234 mm Hg. Art. At the same time 0.350 kg of water (evaporation 70%). After cooling the mixture to 20 ° C, the crystals are separated from the mother liquor in a centrifuge and washed six times (portions of 0.100 kg with 47.5% solution of AH salt, containing 0.0023% DACG and having (color index 21.5). As a result, 0.406 kg of a moist AH sun are obtained with a content of 0.026 kg of water, 0.0029% DACG and having a color index of 8.0, 0.244 kg of a stock solution containing 47.5% of AG salt and having a color index of 100, and 6 solutions after washing 0.97-0.103 kg, containing 47.5% salt of AG.

PREMIER 2. 1.0 kg of 30% sol solution, containing 0.031% DACG and with a color index of 100, obtained from HMD with a content of 0.07% DACG, is heated with nitrogen at a temperature of 60 ° С and residual pressure of 149 mm Hg. Art. At the same time, 0.595 kg of water is distilled off (evaporation rate 85%). After cooling the mixture to 20 ° C, the crystals are separated from the mother point by filtration. Under a vacuum and washed with four poros

qi (0.105 kg of the same solution; pa salt of AG as in the streamer 1. As a result, 0.270 kg of wet crystals containing 00341 kg of water (12.6%) and 00021% of DACG having a color index of 6.0 are obtained. ; 0.135 kg of an uterine solution with a content of 0.092%, DAGTS and a color index of 100 and 4 servings of solutions from washing with 0.100-0.110 kg with a content of salt of AH 47.5%.

PRI me R 3. A mixture of 184 g of AH salt, containing 1, her 0.0017% DACG, and having a color index of 24.5, 106 g of distilled water, 20 g of a 10% aqueous solution of the salt of adipic acid and 1 2- .Diaminocyclohexane: a (content

DACG in a solution of 0.5017), is heated with continuous shaking in a thermostat with a temperature of 70 ° C until complete dissolution of the AH salt. The resulting 59.5% solution of salt AG, containing 0.5% DACG, is placed in a thermostat with

temperature of 25 ° C, where it is kept for 1 hour with vigorous stirring. The born crystals of the AH salt are separated from m, attic, by filtration, and washed five times (in portions: but 30 g) with a 48.75% solution of the AH salt with a DACG content of 0.0017% of a color index of 24.5. Obtain 87.1 g of wet crystals, they are 12.8% water, 0.0018% DACG, having a color index of 7.0; 221.9 g of the uterine solution containing

48.75% salt of AG and 0.77% DACG; solutions after the 4th and 5th washes contain 0.0028 and 0.0018% DACG.

At m er 4. 1.0 kg of a 50% solution of AH salt with a DACG content of 0.25% "indicator

chromaticity 26.0, evaporated in a nitrogen atmosphere, pr, and 70 ° C and residual pressure. 233-234 mm Hg. Art. In this case, 0.30 kg of water is distilled off (evaporation wall 60%). After cooling the mixture to 30 ° C, the crystals are separated from the mother liquor

zeitote, ri (1 ti rinium and washed five times (in portions of 0,100 / sg) with a 50% solution of the AH salt with a DAi content, G 0.0017% and a color index of 6.0. 0.370 kg of wet crystals are obtained, containing 0.025 kg of water (7.5%) and 0.0018% of DACG and a color index of 6.0; 0.330 g of stock solution containing 50% of salt AG, and 5 solutions of washing from 0096-0, each. 104 kg, containing 50% salt of A. g.

PRI me R 5. 1.0 kg of a 50% solution of AH salt containing 0.5% DACG and having a chromaticity index of 76.0, is treated in in example 3 with the difference that for washing the crystals of the AH salt are used sequentially

solutions from 2, 3, 4, and 5th washings of crystals in example 3, and the final washing is carried out with the same solution of salt AG, which is used for washing in example 3. Get the same amount of cr, mattal solution and solutions from Bleed as in Example 3, the crystals contain 0.0023% and have a color index of 4.5.

Example 6. 1.0 kg of 50% solution of salt AG,

received after displacement

a thief (0.330 kg) and a solution from the 1st washing of the crystals (0.100 kg) obtained in Example 4, and 0.570 kg of a 50% solution of salt АG with a content of 0.031% DLHR obtained after partial evaporation of a solution of the salt of AG, applied, c in example 2, (total DACG content 0.5%, color index 100) divided into two parts 0.45 kg (part L) and 0.55 kg (part B). Part B is passed through a column of clarifying charcoal. Moreover, the nerve portion of the solution (0.1 kg) after the column with coal is directed to partial evaporation. Get 0.45 kg of 50% solution of the salt of AG, containing 0.50% DACG and having a color index of 4.0. Both solutions are treated in the same manner as onisano in Example 4, with the difference that for washing the crystals

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SALTS of AG, obtained from solution A, are used successively solutions from 2, 3, 4, and 5th washes, obtained after washing the crystals in example 4. The final is carried out with a solution of pure salt. LH (the same as used to wash the crystals in example 3). The crystals obtained from solution B are washed five times with the same solution of salt AG, with which the final washing of the crystals obtained from solution 1 is carried out. 0.045 kg of solution is used for each step of washing the crystals obtained from both solutions.

Characteristics of the crystals and mother liquor obtained from solutions .4 and B are given in the table.

The data show the possibility of myocrax use of the mother liquors, the possibility of bleaching them by treating them with activated: van, charcoal.

Example 7. 1.0 kg of a 50% salt solution containing 1.1% DACG and having a color index of 04.0 is evaporated in a nitrogen atmosphere at 70 ° C and a residual pressure of 233– 234 mm Hg. Art. In this case, 0.350 kg of water is distilled off (upn degree 70%). After cooling the mixture to 20 ° C, the crystals are separated from the mother liquor in a centrifuge and washed six times (0.100 kg portions) with a 47.5% solution of AH salt, containing 1, im 0.0023% DACG and have 1 dim. color index of 21.5. Get 0,406 kg of wet salt AG with a content of 0,026 kg of water, 0,0099% DAC, and having a color index of 8.0; 0.244 kg of stock solution containing 47.5% of the AH salt and having a color ratio of 100, and 6 solutions after washing with 0.097-0.103 kg containing 47.5% of the AG salt.

Example 8. After treatment with a 50% solution of AH salt containing 2.0% DACG and having a color index of 100, in the same manner as in Example 6 with the difference that the crystals are washed seven times, the same amount of crystals of AG is obtained and queen cell. Moreover, the crystals contain 0.0023% DAG and a color index of 7.0.

Subject invention

The method of purification and isolation of the salt of adipic KN1 SLOT and hexamethylenediamine from aqueous solutions by crystallization, characterized in that, in order to simplify the process and increase the degree of product recovery, the initial solution is evaporated at 70-80 ° C to a concentration of no more than 85% with subsequent cooling of the product. to a temperature not lower than 20 ° С, separating the crystals obtained in this way, for example, f.iltrai and washing them with a saturated solution of the salt of adipic acid and hexamethylene bottom of the mine.