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.
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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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