Preparation method and application of diisopropyl xanthogen tetrasulfide

Abstract

The invention relates to the technical field of rubber auxiliaries, in particular to a preparation method and application of diisopropyl xanthogen tetrasulfide. The preparation method comprises the following steps: S1, carrying out reaction on alkali metal and isopropanol to obtain isopropanol salt, adding a solvent and carbon disulfide into the isopropanol salt, and carrying out reaction to obtain diisopropyl xanthate; s2, sulfur and sulfur dichloride are added into the material obtained after the reaction in the step S1 for a reaction, after the reaction is finished, sodium chloride and unreacted sulfur are removed, the solvent is recycled, and diisopropyl xanthogen tetrasulfide is obtained. According to the method, no water is generated in the reaction process, side reactions can be reduced, and the prepared diisopropyl xanthogen tetrasulfide is high in purity, high in yield, good in stability and not prone to devitrification.

Description

Technical Field

[0001] The invention relates to the technical field of rubber additives, and in particular to a preparation method and application of diisopropyl xanthogen tetrasulfide. Background Art

[0002] Rubber vulcanization accelerators are additives that can accelerate the vulcanization reaction, shorten the vulcanization time, reduce the vulcanization temperature, reduce the amount of vulcanizing agent, and improve the physical and mechanical properties of the vulcanized rubber. The use of accelerators can significantly improve production efficiency, reduce costs, and improve the physical and mechanical properties of rubber products, ensuring the uniformity of product quality and the aesthetic appearance. At present, there are many types of accelerators used in the rubber industry, which are mainly divided into two categories: inorganic accelerators and organic accelerators. Although inorganic accelerators have a long history, they have been replaced by organic accelerators due to their limited promotion effect and poor performance of vulcanized rubber. Organic accelerators have become the mainstream choice of the rubber industry due to their significant promotion effect and good vulcanization characteristics. Xanthates are a type of ultra-fast organic accelerator with particularly high activity, which promotes even faster than ammonium salts of dithiocarbamic acid, and has a very small vulcanization flat range. Due to the chemical properties of diisopropyl xanthate tetrasulfide, it exhibits good heat resistance and aging resistance during rubber vulcanization, which makes it particularly suitable for rubber products in high temperature and harsh environments.

[0003] The existing production process of diisopropyl xanthogen tetrasulfide in China can no longer fully meet the use requirements of the rubber industry. The main reasons are: (1) The traditional process uses peroxide to participate in the reaction, which is a dangerous process; (2) The product is prone to crystallization, odor and other problems; (3) Water is generated when diisopropyl xanthogenate is generated, there are many orange-red by-products, the yield of diisopropyl xanthogenate is low, and the generated water reacts with sulfur monochloride to increase by-products; (4) The existing product is a mixture of isopropyl xanthogen polysulfide compounds, the purity of diisopropyl xanthogen tetrasulfide is less than 70%, and the quality stability is poor.

[0004] Therefore, it is of great significance to develop a production process for diisopropylxanthogen tetrasulfide with mild reaction conditions, no water generation, few side reactions, high product purity and yield, and stable and reliable quality.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first object of the present invention is to provide a method for preparing diisopropyl xanthogen tetrasulfide. No water is generated during the reaction process of the method, and side reactions can be reduced. The prepared diisopropyl xanthogen tetrasulfide has high purity, high yield, good stability, and is not easy to crystallize.

[0007] The second object of the present invention is to provide a use of diisopropyl xanthogen tetrasulfide prepared by the preparation method of diisopropyl xanthogen tetrasulfide as described above in the preparation of rubber vulcanized products.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] A method for preparing diisopropylxanthogen tetrasulfide comprises the following steps:

[0010] S1. reacting an alkali metal and isopropanol to obtain an isopropoxide, and adding a solvent and carbon disulfide to the isopropoxide to obtain diisopropyl xanthate;

[0011] S2. Add sulfur and sulfur dichloride to the material after the reaction in step S1 to react. After the reaction is completed, remove the sodium chloride and unreacted sulfur, recover the solvent, and obtain diisopropyl xanthogen tetrasulfide.

[0012] Preferably, the alkali metal comprises sodium and / or potassium.

[0013] Preferably, in step S1, the molar ratio of the alkali metal, the isopropanol and the carbon disulfide is 0.9-1.2:1-1.5:1-1.5.

[0014] Preferably, in step S1, the reaction temperature for synthesizing the isopropoxide is 5-30° C., and the reaction time is 1-3 h.

[0015] Preferably, in step S1, the solvent includes at least one of dichloromethane, cyclohexane, petroleum ether and toluene.

[0016] Preferably, in step S1, the temperature for reacting the isopropoxide with the carbon disulfide is 25-30°C.

[0017] Preferably, in step S2, the molar ratio of the sulfur, the sulfur dichloride and the diisopropyl xanthate is 1-2:0.9-1.5:0.9-1.5.

[0018] Preferably, in step S2, the reaction temperature for synthesizing the diisopropylxanthogen tetrasulfide is 70-100° C., and the reaction time is 1-3 h.

[0019] Preferably, in step S2, the solvent is recovered by heating, and the temperature of the heating recovery is 45-55°C.

[0020] The diisopropyl xanthogen tetrasulfide prepared by the preparation method of diisopropyl xanthogen tetrasulfide as described above is used in the preparation of rubber vulcanized products.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The method of the present invention produces no water during the entire reaction process, can improve the purity of the intermediate product diisopropyl xanthate, can avoid the side reaction of water and sulfur dichloride, and improve the purity of the product; excess sulfur can promote the forward reaction of sulfur with diisopropyl xanthate trisulfide; the purity of diisopropyl xanthate tetrasulfide in the obtained product can reach 92%, and the yield is as high as 95%.

[0023] In the method of the present invention, the prepared intermediate product diisopropyl xanthate is first reacted with sulfur dichloride to generate diisopropyl xanthate trisulfide, and then reacted with sulfur to generate diisopropyl xanthate tetrasulfide. The tetrasulfide is prepared from the trisulfide. Compared with the method of preparing the tetrasulfide from diisopropyl xanthate, the product has better stability and is not easy to crystallize. DETAILED DESCRIPTION

[0024] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0025] The first aspect of the present invention provides a method for preparing diisopropylxanthogen tetrasulfide, comprising the following steps:

[0026] S1. reacting an alkali metal with isopropanol, filtering to remove excess isopropanol to obtain a paste-like solid isopropoxide, adding a solvent to the obtained isopropoxide, and adding carbon disulfide dropwise to react to obtain diisopropyl xanthate;

[0027] S2. Add sulfur to the material after the reaction in step S1, and drop sulfur dichloride to react. After the reaction is completed, filter out the sodium chloride and unreacted sulfur, recover the solvent, and obtain diisopropyl xanthogen tetrasulfide.

[0028] Taking sodium metal as an example, the specific reaction formula is as follows:

[0029]

[0030] The method of the present invention firstly adopts the reaction of alkali metal and isopropanol to prepare isopropoxide, and then the isopropoxide reacts with carbon disulfide to obtain diisopropyl xanthate, the obtained diisopropyl xanthate first reacts with sulfur dichloride to generate diisopropyl xanthogen trisulfide, and the diisopropyl xanthogen trisulfide then reacts with sulfur to generate diisopropyl xanthogen tetrasulfide. The whole reaction process is free of water, the prepared diisopropyl xanthate has high purity, and the side reaction of water and sulfur dichloride can be avoided, so that the purity of the product can be improved, and the excess sulfur can promote the forward reaction of the sulfur with diisopropyl xanthogen trisulfide, so that the prepared diisopropyl xanthogen tetrasulfide has high purity and high yield, the purity can reach 92%, and the yield can reach 95%.

[0031] The existing method usually uses diisopropyl xanthate to directly react with sulfur monochloride to generate diisopropyl xanthate tetrasulfide, or uses diisopropyl xanthate to add sulfur to directly prepare diisopropyl xanthate tetrasulfide. The prepared diisopropyl xanthate tetrasulfide has poor stability and is easy to crystallize. The method of the present invention first generates diisopropyl xanthate trisulfide by reacting diisopropyl xanthate with sulfur dichloride, and then uses diisopropyl xanthate trisulfide to react with sulfur to prepare diisopropyl xanthate tetrasulfide, which can improve the stability of the product and is not easy to crystallize.

[0032] In some specific embodiments of the present invention, in step S1, the alkali metal used includes sodium and / or potassium.

[0033] In some specific embodiments of the present invention, in step S1, during the preparation of diisopropyl xanthate, the molar ratio of alkali metal, isopropanol and carbon disulfide is 0.9-1.2:1-1.5:1-1.5, for example, 0.9:1:1, 0.9:1:1.2, 0.9:1:1.5, 0.9:1.2:1, 0.9:1.2:1.2, 0.9:1.2:1.5, 0.9:1 Any point value or the range of any two point values ​​among .5:1, 0.9:1.5:1.2, 0.9:1.5:1.5, 1:1:1, 1:1:1.2, 1:1:1.5, 1:1.2:1, 1:1.2:1.3, 1:1.2:1.5, 1:1.5:1, 1:1.5:1.3, 1:1.5:1.5, 1.2:1.3:1, 1.2:1.3:1.5.

[0034] In some specific embodiments of the present invention, in step S1, the reaction temperature for synthesizing isopropoxide from alkali metal and isopropanol is 5-30°C, for example, it can be any value among 5°C, 10°C, 15°C, 20°C, 25°C, and 30°C, or a range consisting of any two values; the reaction time is 1-3h, for example, it can be any value among 1h, 1.5h, 2h, 2.5h, and 3h, or a range consisting of any two values.

[0035] In some specific embodiments of the present invention, in step S1, the solvent used includes at least one of dichloromethane, cyclohexane, petroleum ether and toluene.

[0036] In some specific embodiments of the present invention, in step S1, the temperature of the reaction of isopropoxide and carbon disulfide is 25-30°C. The process of adding carbon disulfide is exothermic. By controlling the dropping speed of carbon disulfide, the system temperature is controlled within the range of 25-30°C.

[0037] In some specific embodiments of the present invention, in step S2, the molar ratio of sulfur, sulfur dichloride and diisopropyl xanthate is 1-2: 0.9-1.5: 0.9-1.5, for example, it can be any point value or a range value composed of any two point values ​​in 1: 0.9: 0.9, 1.2: 0.9: 1, 1.2: 0.9: 1.2, 1.2: 1: 0.9, 1.2: 1: 1.2, 1.6: 1: 1.1, 1.6: 1.2: 1.5, 1.85: 1: 1.2, 1.85: 1.3: 1.5, 2: 1.5: 1.5; wherein the molar amount of diisopropyl xanthate is the theoretical molar amount generated by the reaction. Controlling sulfur to be slightly excessive within the above ratio range can promote the forward reaction of sulfur and diisopropyl xanthate trisulfide.

[0038] In some specific embodiments of the present invention, in step S2, the reaction temperature for synthesizing diisopropyl xanthate with sulfur dichloride and sulfur to form diisopropyl xanthate tetrasulfide is 70-100°C, for example, it can be any value among 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or a range consisting of any two values; the reaction time is 1-3h, for example, it can be any value among 1h, 1.5h, 2h, 2.5h, 3h, or a range consisting of any two values; the process of adding sulfur dichloride is exothermic, and the system temperature can be controlled within the above range by controlling the dripping rate of sulfur dichloride.

[0039] In some specific embodiments of the present invention, in step S2, the method for recovering the solvent is to heat the filtrate after filtration and recover the solvent, and the temperature for heating the recovered solvent is 45-55°C, for example, it can be any point value among 45°C, 48°C, 50°C, 52°C, 55°C or a range value consisting of any two point values.

[0040] A second aspect of the present invention provides use of diisopropyl xanthogen tetrasulfide prepared by the method for preparing diisopropyl xanthogen tetrasulfide according to any one of the aforementioned embodiments in preparing a rubber vulcanized product.

[0041] The following is a detailed description of some embodiments of the present invention in conjunction with specific examples. The raw materials used in the examples can be purchased from the market unless otherwise specified.

[0042] Example 1

[0043] S1. 10g of sodium metal was added to 31.3g of isopropanol in batches and reacted at room temperature (25°C) for 2h. After the reaction, a paste solid was obtained by filtration, put into a three-necked flask, 92g of dichloromethane was added, and 33g of carbon disulfide was added dropwise. The dropping speed was controlled so that the temperature of the reaction system was controlled at 25-30°C. Yellow crystals precipitated during the reaction;

[0044] S2. Add 14 g of sulfur to the material after the reaction in step S1, stir evenly, raise the temperature to 80° C., add 37 g of sulfur dichloride dropwise, react for 2 h, filter out sodium chloride and unreacted sulfur, and then raise the temperature to 55° C. to recover dichloromethane to obtain diisopropyl xanthogen tetrasulfide.

[0045] Example 2

[0046] S1. 10g of sodium metal was added to 39.3g of isopropanol in batches and reacted at room temperature (25°C) for 2h. After the reaction, a paste solid was obtained by filtration, which was put into a three-necked flask, 92g of dichloromethane was added, and 49.56g of carbon disulfide was added dropwise. The dropping speed was controlled so that the temperature of the reaction system was controlled at 25-30°C. Yellow crystals were precipitated during the reaction.

[0047] S2. Add 18 g of sulfur to the material after the reaction in step S1, stir evenly, raise the temperature to 80° C., add 48 g of sulfur dichloride dropwise, react for 2 h, filter out sodium chloride and unreacted sulfur, and then raise the temperature to 50° C. to recover dichloromethane to obtain diisopropyl xanthogen tetrasulfide.

[0048] Example 3

[0049] S1. 10g of sodium metal was added to 39.3g of isopropanol in batches and reacted at room temperature (25°C) for 2h. After the reaction, a paste solid was obtained by filtration, which was put into a three-necked flask, 91.3g of cyclohexane was added, and 42.95g of carbon disulfide was added dropwise. The dropping speed was controlled so that the temperature of the reaction system was controlled at 25-30°C. Yellow crystals were precipitated during the reaction.

[0050] S2. Add 20 g of sulfur to the material after the reaction in step S1, stir evenly, raise the temperature to 80° C., add 40 g of sulfur dichloride dropwise, react for 2 h, filter out sodium chloride and unreacted sulfur, and then raise the temperature to 48° C. to recover cyclohexane to obtain diisopropyl xanthogen tetrasulfide.

[0051] Example 4

[0052] S1. 16g of potassium metal was added to 29.54g of isopropanol in batches and reacted at room temperature (25°C) for 2h. After the reaction, a paste solid was obtained by filtration, which was put into a three-necked flask, 86.15g of cyclohexane was added, and 31.18g of carbon disulfide was added dropwise. The dropping speed was controlled so that the temperature of the reaction system was controlled at 25-30°C. Yellow crystals were precipitated during the reaction.

[0053] S2. Add 20 g of sulfur to the material after the reaction in step S1, stir evenly, raise the temperature to 80°C, add 34.9 g of sulfur dichloride dropwise, react for 2 hours, filter out sodium chloride and unreacted sulfur, and then raise the temperature to 45°C to recover cyclohexane to obtain diisopropyl xanthogen tetrasulfide.

[0054] Comparative Example 1

[0055] Comparative Example 1 is similar to Example 1, except that the metallic sodium in step S1 is replaced with an equimolar amount of sodium hydroxide, and the other conditions are the same as those in Example 1.

[0056] Comparative Example 2

[0057] Comparative Example 2 is similar to Example 1, except that in step S2, sulfur monochloride (S2Cl2) is directly added to the material after the reaction in step S1, and the dropping temperature is 25-35°C. Diisopropyl xanthate is reacted with sulfur monochloride to prepare diisopropyl xanthogen tetrasulfide.

[0058] Comparative Example 3

[0059] Diisopropyl xanthate and sulfur were reacted to prepare diisopropyl xanthate tetrasulfide. The molar ratio of diisopropyl xanthate to sulfur was 1:2, the reaction temperature was 85°C, and the reaction time was 2h.

[0060] Test example

[0061] (1) The yield and purity of diisopropylxanthogen tetrasulfide prepared in each embodiment and each comparative example were tested respectively, and the testing method was as follows:

[0062] Purity: Detected by liquid chromatography external standard method. Chromatographic conditions: Chromatographic column: TSKgel ODS-100V C18 (4.6mm×250mm, 5μm); mobile phase acetonitrile and 0.5% HAc aqueous solution, ratio (%, v / v) = 95:5; flow rate 0.8mL / min; detection wavelength 240nm; injection volume 20μL; column temperature 20℃.

[0063] Yield: Yield = actual mass × purity / theoretical mass × 100%.

[0064] The test results are shown in Table 1.

[0065] Table 1

[0066]

[0067]

[0068] (2) The thermal stability of diisopropyl xanthogen tetrasulfide prepared in each embodiment and each comparative example was tested respectively, and the testing method was as follows:

[0069] The product was stored in an oven at 80°C and the crystallization was observed.

[0070] The test results are shown in Table 2.

[0071] Table 2

[0072] Example 1 No crystallization and no odor in 14 days Example 2 No crystallization and no odor in 14 days Example 3 No crystallization and no odor in 14 days Example 4 No crystallization and no odor in 14 days Comparative Example 1 After 6 days, pale yellow crystals precipitate with a pungent odor. Comparative Example 2 After 2 days, pale yellow crystals precipitate with a pungent odor. Comparative Example 3 After 2 days, pale yellow crystals precipitate with a pungent odor.

[0073] From the above results, it can be seen that the purity of diisopropyl xanthogen tetrasulfide can be significantly improved by reducing the production of water through the reaction of alkali metal and isopropanol. Diisopropyl xanthogen salt reacts with sulfur dichloride to generate diisopropyl xanthogen trisulfide, and then diisopropyl xanthogen trisulfide is reacted with sulfur to prepare diisopropyl xanthogen tetrasulfide, which can improve the stability of the product, is not easy to crystallize, and has no odor.

[0074] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing diisopropylxanthogen tetrasulfide, characterized in that: The following steps are involved: S1. reacting an alkali metal and isopropanol to obtain an isopropoxide, and adding a solvent and carbon disulfide to the isopropoxide to obtain diisopropyl xanthate; S2. Add sulfur and sulfur dichloride to the material after the reaction in step S1 to react. After the reaction is completed, remove the sodium chloride and unreacted sulfur, recover the solvent, and obtain diisopropyl xanthogen tetrasulfide.

2. The method for preparing diisopropylxanthogen tetrasulfide according to claim 1, characterized in that: The alkali metal includes sodium and / or potassium.

3. The method for preparing diisopropylxanthogen tetrasulfide according to claim 1, characterized in that: In step S1, the molar ratio of the alkali metal, the isopropanol and the carbon disulfide is 0.9-1.2:1-1.5:1-1.

5.

4. The method for preparing diisopropylxanthogen tetrasulfide according to claim 1, characterized in that: In step S1, the reaction temperature for synthesizing the isopropoxide is 5-30° C., and the reaction time is 1-3 h.

5. The method for preparing diisopropylxanthogen tetrasulfide according to claim 1, characterized in that: In step S1, the solvent includes at least one of dichloromethane, cyclohexane, petroleum ether and toluene.

6. The method for preparing diisopropylxanthogen tetrasulfide according to claim 1, characterized in that: In step S1, the temperature for the reaction of the isopropoxide and the carbon disulfide is 25-30°C.

7. The method for preparing diisopropylxanthogen tetrasulfide according to claim 1, characterized in that: In step S2, the molar ratio of the sulfur, the sulfur dichloride and the diisopropyl xanthate is 1-2:0.9-1.5:0.9-1.

5.

8. The method for preparing diisopropylxanthogen tetrasulfide according to claim 1, characterized in that: In step S2, the reaction temperature for synthesizing the diisopropylxanthogen tetrasulfide is 70-100° C., and the reaction time is 1-3 h.

9. The method for preparing diisopropylxanthogen tetrasulfide according to claim 1, characterized in that: In step S2, the solvent is recovered by heating, and the temperature of the heating recovery is 45-55°C.

10. Use of diisopropyl xanthogen tetrasulfide prepared by the method for preparing diisopropyl xanthogen tetrasulfide according to any one of claims 1 to 9 in preparing rubber vulcanized products.

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