A method for preparing tetraalkylthiuram disulfide

Abstract

The invention discloses a method for preparing tetraalkylthiuram disulfide, which uses secondary amine, carbon disulfide and hydrogen peroxide as raw materials, uses water as the reaction medium, and does not require an organic solvent or acid. The method for preparing tetraalkylthiuram disulfide of the invention does not use acid, uses water as the reaction medium, and does not require an organic solvent. The method eliminates the potential safety hazard caused by the use of solvents in production, saves the energy consumed by solvent recovery, eliminates the environmental problems caused by distillation residues, eliminates the potential safety hazard caused by a large amount of acid and alkali corrosive raw materials in production, eliminates a large amount of wastewater containing inorganic salts, reduces environmental pressure, and does not use solvents, thereby improving the yield of the product.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber vulcanization accelerators and relates to a method for preparing tetraalkylthiuram disulfide. Background Art

[0002] At present, the methods for producing tetraalkylthiuram disulfide mainly include a two-step alkali method and a solvent hydrogen peroxide method.

[0003] Publication No. CN108395393A discloses a green synthesis method for a thiuram rubber vulcanization accelerator. The process of the patent is a two-step alkali method, which has the following shortcomings:

[0004] 1. The molar ratio of secondary amine to alkali metal carbonate is 1:0.5. In the oxidation stage, carbon dioxide is introduced to generate carbonate. The mother liquor can be recycled 3 to 5 times, but it will inevitably produce more inorganic salt wastewater. Especially after the fifth cycle, a large amount of high-concentration inorganic salt wastewater will inevitably be produced.

[0005] 2. The composition of the mother liquor is relatively complex, including not only carbonates, but also residual carbon disulfide, oxidation products of secondary amines, oxidation byproducts of dialkyl disulfide carbamic acid, and many other byproducts. The use of the mother liquor greatly reduces the quality of the product, such as the color and melting point of the product.

[0006] 3. Since the mother liquor contains a large amount of carbonate, a certain amount of carbonate remains in the filter cake after the mother liquor is squeezed out. To wash away the residual carbonate, a large amount of water is needed, thus generating a lot of waste water.

[0007] 4. This patent uses carbon dioxide, which is sourced from dry ice. Dry ice is a low-temperature storage item that is highly volatile. However, the transportation, storage and use of dry ice pose great safety risks.

[0008] 5. This patent is about reducing the generation of wastewater and inorganic salts, not eliminating the generation of wastewater and inorganic salts.

[0009] The publication number is CN104326956A, a method for preparing tetrabenzylthiuram disulfide, a rubber vulcanization accelerator, wherein the raw materials used in the method and their molar ratio are dibenzylamine: carbon disulfide: sodium hydroxide: hydrogen peroxide: sulfuric acid = 1:1-1.3:1.0-1.2:0.05-0.6:0.28-0.35. The process of the patent is a two-step alkali method. The processes of CN104829509A and CN100558706C are also two-step alkali methods, both of which use a large amount of sodium hydroxide and sulfuric acid, (i) generating a large amount of inorganic salt-containing wastewater, and (ii) using a large amount of acid and alkali corrosive raw materials, which will lead to production safety hazards.

[0010] The processes with publication numbers CN101948417A, CN105541683A and CN1962627A are solvent hydrogen peroxide methods. (i) the solvents used, such as methanol, ethanol, isopropanol and n-butanol, are Class II and Class III hazardous chemicals, which pose a great safety hazard to production; (ii) distillation and recovery of these solvents consumes a large amount of energy; (iii) the distillation residue poses a great difficulty to environmental protection; and (iv) since the product has a certain solubility in the solvent, the yield is low. Summary of the invention

[0011] In order to solve the shortcomings of the above technologies, the present invention discloses a method for preparing tetraalkylthiuram disulfide, which is a process of replacing the solvent with water, adding a very small amount of alkaline auxiliary agent, and oxidizing with hydrogen peroxide.

[0012] The preparation method of tetraalkylthiuram disulfide of the present invention uses secondary amine, carbon disulfide, hydrogen peroxide, water and auxiliary agent as raw materials, and the reaction principle is to add auxiliary agent to the aqueous solution of secondary amine, drop carbon disulfide at a certain temperature, obtain intermediate after the reaction is completed, and keep the temperature for 1-5 hours. At a certain temperature, slowly drop hydrogen peroxide in the solution of the intermediate until the hydrogen peroxide is added, and keep the temperature for 1-4 hours after the addition to obtain tetraalkylthiuram disulfide.

[0013] One purpose of the present invention is to solve the problem of a large amount of inorganic salt wastewater caused by the acid-base method. Another purpose is to solve the hidden dangers of production safety caused by the use of a large amount of corrosive raw materials such as acids and alkalis. Another purpose is to solve the hidden dangers of production safety caused by the use of a large amount of flammable and explosive solvents in the solvent method. Another purpose is to solve the environmental pressure and energy waste caused by distillation and recovery of these solvents. Another purpose is to solve the problems of product yield and so on.

[0014] The preparation method of tetraalkylthiuram disulfide of the invention uses secondary amine, carbon disulfide and hydrogen peroxide as raw materials, uses water as the reaction medium, and does not require organic solvents and acids.

[0015] In some embodiments of the present invention, the following steps are included:

[0016] S01, mixing the secondary amine, the auxiliary agent and water, and mixing with carbon disulfide to react;

[0017] S02, mixed with hydrogen peroxide, reacts;

[0018] S03, filtering, washing with water and drying to obtain the tetraalkylthiuram disulfide.

[0019] In some embodiments of the present invention, it is characterized in that, in S01, the mixing with carbon disulfide is dropwise adding carbon disulfide.

[0020] In some embodiments of the present invention, in S02, the mixing with hydrogen peroxide is dropwise adding hydrogen peroxide.

[0021] In some embodiments of the present invention, the secondary amine is at least one of dimethylamine, diethylamine, diisobutylamine, dibenzylamine and N-methylaniline.

[0022] In some embodiments of the present invention, the auxiliary agent is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide and potassium hydroxide.

[0023] In some embodiments of the present invention, the water is deionized water.

[0024] In some embodiments of the present invention, the ratio of the amount of the secondary amine, carbon disulfide, hydrogen peroxide and the auxiliary agent is 1:(1-1.6):(0.5-0.7):(0.01-0.2).

[0025] In some embodiments of the present invention, in S01, the reaction temperature is 10-50°C, the reaction time is 0.5-5h, and the endpoint of the reaction is pH 7-10.

[0026] In some embodiments of the present invention, in S02, the reaction temperature is 10-50°C, the reaction time is 0.5-4h, and the end point of the reaction is pH 3-7.

[0027] Beneficial effects of the present invention:

[0028] The method for preparing tetraalkylthiuram disulfide of the present invention can obtain tetraalkylthiuram disulfide in the form of white crystalline powder or white crystalline particles, with a yield of more than 99.0% and a purity greater than 99.5% as determined by HPLC.

[0029] The preparation method of tetraalkylthiuram disulfide of the present invention does not require acid, the reaction medium is water, and no organic solvent is required. The potential safety hazard caused by the use of solvents in production is eliminated; the energy consumed by the recovery of solvents is saved; the environmental protection problem caused by the distillation residue is eliminated; the potential safety hazard caused by a large amount of acid and alkali corrosive raw materials in production is eliminated; a large amount of waste water containing inorganic salts is eliminated, and the environmental protection pressure is reduced; and the yield of the product is improved by not using solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0031] Figure 1 The present invention is a process flow chart of the preparation method of tetraalkylthiuram disulfide. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0033] Unless otherwise specified, the examples and comparative examples are parallel tests with the same components, component contents, preparation steps and preparation parameters.

[0034] The raw materials used in the reaction are secondary amine, carbon disulfide, hydrogen peroxide and an auxiliary agent, and the solvent used is deionized water.

[0035] Example 1

[0036] A certain amount of deionized water was first added to the reactor, followed by 129.24 kg of diisobutylamine and 1.06 kg of sodium carbonate. The stirring was started, the cooling water was turned on, 77.69 kg of carbon disulfide was added dropwise at 25° C., and the mixture was kept warm at 10-30° C. for 2 hours. 74.18 kg of 27.5% (w / w) perhydroperoxide was added dropwise at 10-30° C., and the mixture was kept warm for 1 hour after the perhydroperoxide was added dropwise. The mixture was then washed, dehydrated, dried, and crushed to obtain 202.74 kg of tetraisobutylthiuram disulfide with a yield of 99.2%.

[0037] Example 2

[0038] First, add a certain amount of deionized water to the reaction kettle, then add 112.5kg of 40% (w / w) dimethylamine aqueous solution and 2.76kg of potassium carbonate, start stirring, turn on cooling water, and add 85.46kg of carbon disulfide dropwise at 35°C until the addition is complete. After the addition is complete, keep the temperature at 30-40°C for 3 hours, and then add 61.82kg of 27.5% (w / w) perhydrogen peroxide dropwise at 40-50°C. After the perhydrogen peroxide is added, keep the temperature for 2 hours, wash, dehydrate, dry, and crush to obtain 119.0kg of tetramethylthiuram disulfide, with a yield of 99.0%.

[0039] Example 3

[0040] A certain amount of deionized water was first added to the reactor, followed by 73.14 kg of diethylamine and 32% 12.5 kg of sodium hydroxide, stirring was started, cooling water was turned on, 87.56 kg of carbon disulfide was added dropwise at 30°C, and the mixture was kept warm at 35°C for 2 hours. 68.0 kg of 27.5% (w / w) perhydroperoxide was added dropwise at 20°C, and the mixture was kept warm for 2 hours after the perhydroperoxide was added, and then washed, dehydrated, dried, and crushed to obtain 147.28 kg of tetraethylthiuram disulfide with a yield of 99.34%.

[0041] Example 4

[0042] A certain amount of deionized water was first added to the reactor, followed by 197.28 kg of dibenzylamine and 7.9 kg of 85% potassium hydroxide, stirring was started, cooling water was turned on, 82.23 kg of carbon disulfide was added dropwise at 40°C, after which the mixture was kept at 35-45°C for 4 hours, 86.54 kg of 27.5% (w / w) perhydroperoxide was added dropwise at 45°C, after which the mixture was kept at 35-45°C for 4 hours, perhydroperoxide was added dropwise, after which the mixture was kept at 35-45°C for 2 hours, washing, dehydration, drying and crushing were performed to obtain 270 kg of tetrabenzylthiuram disulfide with a yield of 99.5%.

[0043] Example 5

[0044] A certain amount of deionized water was first added to the reactor, followed by 107.15 kg of N-methylaniline and 8.4 kg of sodium bicarbonate. Stirring was started, cooling water was turned on, 77.69 kg of carbon disulfide was added dropwise at 25° C., after the addition was completed, the mixture was kept warm at 10-30° C. for 3 hours, and 74.18 kg of 27.5% (w / w) perhydroperoxide was added dropwise at 20° C. After the addition of perhydroperoxide, the mixture was kept warm for 1 hour, washed, dehydrated, dried, and crushed to obtain 181.47 kg of dimethyl diphenylthiuram disulfide with a yield of 99.45%.

[0045] The preferred specific implementation modes and embodiments of the present invention are described in detail above, but the present invention is not limited to the above implementation modes and embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the concept of the present invention.

Claims

1. A method for preparing tetraalkylthiuram disulfide, characterized in that: The raw materials are secondary amine, carbon disulfide and hydrogen peroxide, the reaction medium is water, and no organic solvent and acid are required; The following steps are involved: S01, mixing a secondary amine, an auxiliary agent and water, and mixing with carbon disulfide, and reacting; the reaction temperature is 10-50° C., and the end point of the reaction is pH 7-10; the auxiliary agent is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide and potassium hydroxide; S02, mixed with hydrogen peroxide, reacted; the reaction temperature is 10-50°C, and the end point of the reaction is pH 3-7; S03, filtering, washing with water, and drying to obtain the tetraalkylthiuram disulfide; the color is white crystalline powder or white crystalline particles, the yield is above 99.0%, and the purity is greater than 99.5% by HPLC detection; The ratio of the amount of the secondary amine, carbon disulfide, hydrogen peroxide and the auxiliary agent is 1:(1-1.6):(0.5-0.7):(0.01-0.2).

2. The preparation method according to claim 1, characterized in that: In S01, the mixing with carbon disulfide is dropwise adding carbon disulfide; In S02, the mixing with hydrogen peroxide is dropwise addition of hydrogen peroxide.

3. The preparation method according to claim 1 or 2, characterized in that: The secondary amine is at least one of dimethylamine, diethylamine, diisobutylamine, dibenzylamine and N-methylaniline.

4. The preparation method according to claim 1 or 2, characterized in that: The water is deionized water.

5. The preparation method according to claim 1 or 2, characterized in that: In S01, the reaction temperature is 10-50°C, the reaction time is 0.5-5h, and the end point of the reaction is pH 7-10.

6. The preparation method according to claim 1 or 2, characterized in that: In S02, the reaction temperature is 10-50°C, the reaction time is 0.5-4h, and the end point of the reaction is pH 3-7.

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