A PRODUCTION METHOD FOR THE ANTIOXIDANT H

Abstract

The present invention discloses a production method for antioxidant H, comprising the following steps: Step 1: Preparing 1,4-cyclohexanedione, aniline, and dehydrated sulfate in a molar ratio of 1:(2-3):(1-3), and then preparing an organic solvent in which the mass ratio of 1,4-cyclohexanedione to the organic solvent is 1:(6-15); Step 2: Dissolving 1,4-cyclohexanedione, aniline, and dehydrated sulfate in the organic solvent, stirring thoroughly and supplying air, and reacting thoroughly at 0 to 50°C to obtain product A; Step 3: Successively filtering, washing, drying, and crushing product A to obtain antioxidant H.The production method of the invention not only ensures a simple process flow, low emissions of exhaust gas, wastewater and solid waste, and low energy consumption, but also ensures a high yield and high purity of the antioxidant H, which is practical for industrial production.

Description

Field of the invention

[0001] The present invention relates to the technical field of organic chemistry and in particular to a production method for the antioxidant H. State of the art

[0002] The chemical name of the antioxidant H is N,N'-diphenyl-p-phenylenediamine with the molecular formula C 18 H 16 N2 and the following molecular structure:

[0003] Antioxidant H is a widely used antioxidant for natural and synthetic rubber. It exhibits excellent flexural crack resistance and provides excellent protection against heat, oxygen, ozone, light, and especially against copper and manganese ions without affecting vulcanization. Antioxidant H can be used in natural rubber, as well as styrene-butadiene rubber, acrylonitrile-butadiene rubber, polybutadiene, butyl rubber, HTPB (hydroxyl-terminated polybutadiene), and polyisoprene rubber. It can also be used as a heat and oxidation stabilizer in engineering plastics such as polyethylene, polypropylene, polyamide, and polyoxymethylene. In addition, Antioxidant H is also used in composite solid propellants to extend the storage life of solid propellants. Antioxidant H is still widely used in solid propellants at home and abroad.

[0004] Currently, antioxidant H is mainly produced in industry through a condensation reaction of hydroquinone and aniline. However, products produced by this conventional method have problems such as low active ingredient content, easy melting, and high production pollution. Typically, the active ingredient content is no more than 90%, and the melting point of the product does not exceed 125°C. Chinese patent CN103102507 discloses a method for producing p-phenylenediamine antioxidant using ferric chloride as a catalyst, a high-temperature reaction, followed by water washing and distillation to obtain a product. However, this method requires strict reaction conditions, involves numerous high-temperature and vacuum processes, and places high demands on equipment.In addition, the water washing process generates a large amount of wastewater containing salt and organic matter, which is difficult to treat. Therefore, the conventional production method for antioxidant H faces serious environmental problems.

[0005] In the publication "One-step synthesis of N,N'-dialkyl-p-phenylenediamines" (Luke T. Higham, Green Chem., 2007, 9, 80-84), the reaction of 1,4-cyclohexanedione with amines to produce p-phenylenediamines was investigated. However, the yield of the synthesized antioxidant H was only 43%. The reaction process involves a high-temperature reflux reaction, which produces more byproducts. Given the high price of 1,4-cyclohexanedione and the extremely low yield of antioxidant H, this preparation method obviously has no industrial value. Therefore, improving the reaction conditions of 1,4-cyclohexanedione and aniline is promising, increasing the reaction yield of antioxidant H, thus replacing the conventional preparation method of antioxidant H and providing an effective solution to the current challenges in antioxidant H production. Object of the invention

[0006] The invention is based on the object of avoiding the above-mentioned disadvantages of the prior art and of providing a production method for the antioxidant H which not only improves the yield and purity of the antioxidant H but also minimizes environmental pollution.

[0007] To solve the above task, the following technical solutions are used: a production method for the antioxidant H, which includes the following steps: Step 1: Prepare 1,4-cyclohexanedione, aniline and dehydrated sulfate in a molar ratio of 1:(2-3):(1-3) and then prepare an organic solvent in which the mass ratio of 1,4-cyclohexanedione to the organic solvent is 1:(6-15); Step 2: Dissolving 1,4-cyclohexanedione, aniline and dehydrated sulfate in the organic solvent, stirring thoroughly and supplying air, and reacting thoroughly at 0 to 50 °C to obtain a product A; Step 3: Successively filtering, washing, drying and crushing the product A to obtain an antioxidant H, wherein the antioxidant is HN,N'-diphenyl-p-phenylenediamine.

[0008] Furthermore, the dehydrated sulfate in step 1 is sodium sulfate or magnesium sulfate.

[0009] Furthermore, the organic solvent in step 1 is anhydrous ethanol or ethyl acetate.

[0010] Furthermore, in step 2, air is supplied in an amount of 0.3 to 1.5 l / min per mole of 1,4-cyclohexanedione under standard conditions.

[0011] Furthermore, in step 2 the reaction time is 8 to 48 hours.

[0012] Furthermore, in step 3, washing with deionized water is carried out until the conductivity of product A is less than 50 µS / cm.

[0013] Compared to the prior art, the present invention achieves the following technical effects: 1) In the present invention, dehydrated sulfate is added as a reaction catalyst, which can react with water generated during the reaction to promote the reaction and significantly improve the reaction yield. The product yield can reach up to 85% or more depending on the amount of 1,4-cyclohexanedione added. 2) The treatment process of the present invention is simple. After the reaction is complete, antioxidant H with a purity of over 98% can be obtained by simple filtration, washing, and drying. Since the unreacted raw materials are soluble in organic solvents and water, they can be recovered and reused after filtration. 3) In the present invention, the reaction is carried out at low temperatures and under mild conditions, which means that the equipment requirements are low and the investment in industrial equipment is kept low; 4) Compared with conventional processes, the present invention produces less exhaust gas, wastewater, and solid waste. No acidic or alkaline wastewater is discharged, and only a small amount of saline wastewater is generated during the washing process, which can be easily recycled and treated. 5) In the present invention, the air supplied during the reaction process can be recycled, thereby minimizing the exhaust gases. Short description of the drawing Fig. 1 shows a chromatogram of Antioxidant H prepared by the first embodiment of the present invention. Detailed description of the implementation examples

[0014] The content of the present invention is explained in more detail below using exemplary embodiments. Example 1 Step 1: Prepare 1 mol of 1,4-cyclohexanedione, 2 mol of aniline, 672 g of anhydrous ethanol and 1 mol of dehydrated sodium sulfate; Step 2: Dissolve 1,4-cyclohexanedione, aniline and dehydrated sodium sulfate in anhydrous ethanol, stir thoroughly and supply 0.3 l / min of air and react thoroughly at 30 °C for 8 hours to obtain a product A; Step 3: Filter the product A, wash it with deionized water until its conductivity is less than 50 µS / cm and then dry and grind it to obtain an antioxidant H.

[0015] In Example 1, a total of 153.6 g of antioxidant H were obtained, with a product yield of 59.0% and a purity of the antioxidant H of 98.1%.

[0016] Fig. Figure 1 shows a chromatogram of Antioxidant H prepared in the first embodiment, measured by gas chromatography-mass spectrometry GCMS-QP2010 SE. From the graph, it can be seen that the sample prepared by the present invention is N,N'-diphenyl-p-phenylenediamine (namely, Antioxidant H) and the sample has a high purity. Example 2 Step 1: Prepare 1 mol of 1,4-cyclohexanedione, 2.5 mol of aniline, 896 g of anhydrous ethanol and 2 mol of dehydrated sodium sulfate; Step 2: Dissolve 1,4-cyclohexanedione, aniline and dehydrated sodium sulfate in anhydrous ethanol, stir thoroughly and supply 0.6 l / min of air and react thoroughly at 30 °C for 15 hours to obtain a product A; Step 3: Filter the product A, wash it with deionized water until its conductivity is less than 50 µS / cm and then dry and grind it to obtain an antioxidant H.

[0017] In Example 2, a total of 183.8 g of antioxidant H were obtained, with a product yield of 70.6% and a purity of the antioxidant H of 98.1%. Example 3 Step 1: Prepare 1 mole of 1,4-cyclohexanedione, 3 moles of aniline, 1120 g of anhydrous ethanol and 2 moles of dehydrated sodium sulfate; Step 2: Dissolve 1,4-cyclohexanedione, aniline and dehydrated sodium sulfate in anhydrous ethanol, stir thoroughly and supply 1.0 L / min of air and react thoroughly at 40 °C for 32 hours to obtain a product A; Step 3: Filter the product A, wash it with deionized water until its conductivity is less than 50 µS / cm and then dry and grind it to obtain an antioxidant H.

[0018] In Example 3, a total of 227.8 g of antioxidant H were obtained, with a product yield of 87.5% and a purity of the antioxidant H of 98.5%. Example 4 Step 1: Prepare 1 mol of 1,4-cyclohexanedione, 3 mol of aniline, 1120 g of ethyl acetate and 2 mol of dehydrated magnesium sulfate; Step 2: Dissolve 1,4-cyclohexanedione, aniline and dehydrated magnesium sulfate in ethyl acetate, stir thoroughly and supply 1.0 L / min of air and react thoroughly at 10 °C for 40 hours to obtain a product A; Step 3: Filter the product A, wash it with deionized water until its conductivity is less than 50 µS / cm and then dry and grind it to obtain an antioxidant H.

[0019] In Example 4, a total of 223.4 g of antioxidant H were obtained, with a product yield of 85.8% and a purity of the antioxidant H of 98.0%. Example 5 Step 1: Prepare 1 mole of 1,4-cyclohexanedione, 3 moles of aniline, 1680 g of ethyl acetate and 3 moles of dehydrated magnesium sulfate; Step 2: Dissolve 1,4-cyclohexanedione, aniline and dehydrated magnesium sulfate in ethyl acetate, stir thoroughly and supply 1.2 l / min of air and react thoroughly at 0 °C for 48 hours to obtain a product A; Step 3: Filter the product A, wash it with deionized water until its conductivity is less than 50 µS / cm and then dry and grind it to obtain an antioxidant H.

[0020] In Example 5, a total of 178.3 g of antioxidant H were obtained, with a product yield of 68.5% and a purity of the antioxidant H of 98.2%. Example 6 Step 1: Prepare 1 mole of 1,4-cyclohexanedione, 2 moles of aniline, 1344 g of anhydrous ethanol and 2 moles of dehydrated magnesium sulfate; Step 2: Dissolve 1,4-cyclohexanedione, aniline and dehydrated magnesium sulfate in anhydrous ethanol, stir thoroughly and supply 1.5 l / min of air and react thoroughly at 25 °C for 24 hours to obtain a product A; Step 3: Filter the product A, wash it with deionized water until its conductivity is less than 50 µS / cm and then dry and grind it to obtain an antioxidant H.

[0021] In Example 6, a total of 188.5 g of antioxidant H were obtained, with a product yield of 72.4% and a purity of the antioxidant H of 98.1%. Example 7 Step 1: Prepare 1 mole of 1,4-cyclohexanedione, 2 moles of aniline, 1176 g of anhydrous ethanol and 2 moles of dehydrated magnesium sulfate; Step 2: Dissolve 1,4-cyclohexanedione, aniline and dehydrated magnesium sulfate in anhydrous ethanol, stir thoroughly and supply 0.9 l / min of air and react thoroughly at 50 °C for 28 hours to obtain a product A; Step 3: Filter the product A, wash it with deionized water until its conductivity is less than 50 µS / cm and then dry and grind it to obtain an antioxidant H.

[0022] In Example 7, a total of 183.5 g of antioxidant H were obtained, with a product yield of 70.5% and a purity of the antioxidant H of 98.0%. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 103102507

[0004] Cited non-patent literature

[0000] One-step synthesis of N,N'-dialkyl-p-phenylenediamines” (Luke T. Higham, Green Chem., 2007, 9, 80-84

[0005]

Claims

[1] Production method for the antioxidant H, characterized by that it includes the following steps: Step 1: Prepare 1,4-cyclohexanedione, aniline and dehydrated sulfate in a molar ratio of 1:(2-3):(1-3) and then prepare an organic solvent in which the mass ratio of 1,4-cyclohexanedione to the organic solvent is 1:(6-15); Step 2: Dissolving 1,4-cyclohexanedione, aniline and dehydrated sulfate in the organic solvent, stirring thoroughly and supplying air, and reacting thoroughly at 0 to 50 °C to obtain a product A; Step 3: Successively filtering, washing, drying and crushing the product A to obtain an antioxidant H, wherein the antioxidant is HN,N'-diphenyl-p-phenylenediamine. [2] Method for producing the antioxidant H according to claim 1, characterized by that the dehydrated sulfate in step 1 is sodium sulfate or magnesium sulfate. [3] Production method for the antioxidant H according to claim 1, characterized by that the organic solvent in step 1 is anhydrous ethanol or ethyl acetate. [4] Method for producing the antioxidant H according to claim 1, characterized by that in step 2, air is supplied in an amount of 0.3 to 1.5 l / min per mole of 1,4-cyclohexanedione under standard conditions. [5] Method for producing the antioxidant H according to claim 1, characterized by that in step 2 the reaction time is 8 to 48 hours. [6] Method for producing the antioxidant H according to claim 1, characterized by that in step 3, washing is carried out with deionized water until the conductivity of product A is less than 50 µS / cm.

Images