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Preparation process of p-phenylenediamine

A preparation process and a technology for p-phenylenediamine, which are applied in the field of preparation technology of p-phenylenediamine, can solve the problems of high energy consumption, high raw material price and the like, and achieve the effects of low investment cost, low raw material cost and simple process.

Inactive Publication Date: 2021-07-20
AFCHINA CORP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this process needs to be equipped with stirring vessels, pressure devices and other auxiliary equipment, and at the same time, the energy consumption is high and the price of raw materials is high.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] 50 grams of polyethylene terephthalate fibers were introduced into a 1 liter glass autoclave equipped with a heating device and a stirrer. The autoclave was heated to 200°C, anhydrous gaseous ammonia was added and the pressure was adjusted to 10 atmospheres. The contents of the autoclave were continuously stirred and reacted under the above conditions for 15 hours. After the autoclave was cooled and vented to normal pressure, the dried reaction mixture was extracted twice with 500 mL of methanol. Filter to obtain the residue containing 39.25g of pure diamine terephthalate (92% of theoretical yield in terms of polyethylene terephthalate), which is dispersed in 43.2g (1.08mol ) in a solution of sodium hydroxide and 600mL of water. The chlorine of 38g (535mmol) is added in the sodium hydroxide solution of 43.2g (1.08mol), prepare fresh sodium hypochlorite solution, then sodium hypochlorite solution and 600mL water are added in the above-mentioned suspension under the con...

Embodiment 2

[0020] 10 grams of dry polyethylene terephthalate crumbs and 31 grams of liquid ammonia were added to a 100 ml V4A autoclave. The mixture was heated to 110°C over 15 minutes under vigorous magnetic stirring while the reaction pressure was raised to about 75 atmospheres. After reacting for 5 hours under the above conditions, the autoclave was cooled and vented to normal pressure. The reaction mixture was extracted twice with methanol, and the reaction mixture was a slightly wet pure white product. Filtration afforded 8.45 g (99.0% of theoretical yield) of diamine terephthalic acid extract. The extract is lightly distilled to recover methanol and ethylene glycol. 8.2 g of diamine terephthalate were dispersed in 29.4 g of potassium hydroxide and 250 ml of an aqueous solution at room temperature. The suspension was cooled, and 17.6 g of bromine was added dropwise at 0-5°C. Then vigorously stirred at 15-20° C. for 3 hours to obtain a transparent lemon-colored solution. The sol...

Embodiment 3

[0022] According to the method described in Example 2, 12 g of polyethylene terephthalate polyester was ammonolyzed in liquid phase using 35.8 g of industrial ammonia water. Set the reaction temperature to 125° C., the pressure to 95 atmospheres, and the reaction time to 5 hours. A residue containing 8.2 g of diamine terephthalate and 15.0 g of calcium hydroxide was obtained by filtration and dispersed in 250 ml of an aqueous solution at room temperature under vigorous stirring. 7.3 g of chlorine were gradually added to the cooled suspension at 0-5°C, and the mixture was vigorously stirred at 20°C for 4 hours. The color of the suspension gradually changed from white at the beginning to khaki. The mixture was then heated at 60-65°C for 20 minutes, during which time the reaction mixture turned brown and calcium carbonate precipitated. After heating at 95° C. for 1 hour, p-phenylenediamine was finally separated as described in Example 1. The yield of p-phenylenediamine was 4.5...

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Abstract

The invention discloses a preparation process of p-phenylenediamine, and belongs to the technical field of polymer synthesis. The process method comprises two stages: firstly, in the first stage, one or more terephthalic acid polyesters react with ammonia with the water content of not more than 15% by controlling the reaction temperature to be 50-250 DEG C and the pressure to be 10-300 atmospheric pressure; in the second stage, the product obtained in the first stage reacts with pypocholoride, the ratio of pypocholoride to diamine is controlled to be 2:1-3:1, the temperature is controlled to be 0-30 DEG C, p-phenylenediamine with high purity is obtained; and finally, the product is extracted with chloroform, and drying and distillation are conducted, wherein the highest yield of p-phenylenediamine can reach 94%. The process is simple in flow, low in raw material cost, simple in device structure, low in investment cost, high in continuous operation performance and easy to realize in industrial production.

Description

technical field [0001] The invention belongs to the technical field of polymer synthesis, in particular to a preparation process of p-phenylenediamine. Background technique [0002] p-Phenylenediamine is white or lavender crystal, which easily turns purple or dark brown when exposed to air, and can be sublimated. P-phenylenediamine is widely used. It is not only the main raw material of para-aramid resin, but also used in the preparation of azo dyes, fur dyes, rubber antioxidant photo developers, and p-phenylenediamine is also a sensitive test for iron and copper. Indicating reagent. There are many synthesis processes of p-phenylenediamine, such as reduction of p-nitroaniline and p-dinitrobenzene, catalytic hydrogenation of p-aminoazobenzene, ammonolysis of p-bromoaniline, etc. The current relatively mature process is to reduce p-nitroaniline with iron in hydrochloric acid solution, and the existing implementation scheme of the present invention is: patent 201910084442.1 d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/56C07C211/51C07C231/02C07C233/65
CPCC07C209/56C07C231/02
Inventor 范志平于安军韩郡丰武强强
Owner AFCHINA CORP CO LTD
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