Preparation method of diethyl disulfide

Abstract

The invention discloses a preparation method of diethyl disulfide, and relates to the field of diethyl disulfide production, and the preparation method comprises the following steps: S1, preparing a sodium disulfide solution; step S2, adding the sodium disulfide solution in the step S1 and a catalyst into a reaction kettle, and dropwise adding a reactant into the reaction kettle, and step S3, after the reactant is dropwise added, carrying out a heat preservation reaction; s4, the solution is layered through cooling treatment, the upper layer is an organic phase, and the solution is a crude diethyl disulfide product, and S5, the reaction kettle is subjected to reduced pressure distillation, and the diethyl disulfide solution is obtained. The raw materials are the sodium disulfide solution, the sodium ethyl sulfate solution or the diethyl sulfate solution, the layered solution is obtained through the reaction, the colorless and transparent diethyl disulfide solution is obtained through reduced pressure distillation, the yield and purity of the diethyl disulfide solution are improved, the lower-layer reaction product sodium sulfate water phase can be recycled, and the environmental protection property is improved.

Description

Technical Field

[0001] The invention relates to the field of diethyl disulfide production, and in particular to a method for preparing diethyl disulfide. Background Art

[0002] Diethyl disulfide is a transparent, colorless liquid with a specific gravity of 0.993, a melting point of -95 degrees, a boiling point of 151-153 degrees, and a flash point of 40 degrees. It plays an important role in the field of organic synthesis. Diethyl disulfide can be used as an intermediate in organic synthesis and participate in various chemical reactions to generate target compounds. In the field of pesticide manufacturing, diethyl disulfide is an important intermediate in the production of the fungicide ethyl allicin. Diethyl disulfide can also be used as a cross-linking agent, vulcanizing agent, and bifunctional modifier. It can react with polymers containing amino and hydroxyl groups to form a cross-linked network to improve the strength and wear resistance of the polymer. In addition, it can also be used as a raw material for catalysts, decolorizers, antioxidants, and antibacterial agents.

[0003] Diethyl disulfide is prepared by chemical reaction. In the common preparation method, a disodium disulfide solution is pumped into an alkylation kettle, and after the reactor is evacuated, ethyl chloride is introduced into the reactor, and the reaction temperature is controlled at 75-90°C. After the ethyl chloride is introduced, the material is cooled to below 50°C, and the material oil is pumped into a water separator and allowed to stand for stratification. The upper oil layer is the finished product. The common chemical synthesis method has the disadvantages of complicated process operation, large amount of three wastes discharged, and serious environmental pollution. At the same time, it causes the composition of the reaction product to be complex, which affects the purity of diethyl disulfide. In addition, the price of the raw materials used is relatively high, and the storage, use and transportation have extremely high requirements. It is not suitable for large-scale production and is not convenient for the production and preparation of diethyl disulfide solution. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing diethyl disulfide to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing diethyl disulfide, comprising the following steps:

[0006] Step S1: preparing a sodium disulfide solution;

[0007] Step S2: adding raw materials, adding the sodium disulfide solution and 6.5 g of catalyst in step S1 into the reactor, and then dropping 308 g of the reactants into the reactor;

[0008] Step S3: reaction preparation, after the reactants are added dropwise, the reaction is kept warm, and the end of the reaction is observed by GC detection;

[0009] Step S4: Cooling and stratifying, wherein the solution after the reaction in step S3 is cooled to form stratified layers, wherein the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., crude diethyl disulfide;

[0010] Step S5: distillation and purification, by performing reduced pressure distillation on the reactor, condensing and collecting the distilled gas, to obtain a colorless and transparent diethyl disulfide solution.

[0011] Preferably, the preparation of the sodium disulfide solution in step S1 comprises the following steps:

[0012] Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder;

[0013] Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating and keeping the solution warm, and then adding sulfur powder into the sodium sulfide solution, stirring and mixing;

[0014] Step S13: filtering and cooling. After the reaction is completed, the solution is filtered and cooled. The filtered solution is a sodium disulfide solution.

[0015] Preferably, the reactant in step S2 is one of diethyl sulfate solution and sodium ethyl sulfate solution, and the catalyst is one or more of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400.

[0016] Preferably, the chemical reaction equation generated in the reactor of step S12 is as follows:

[0017] Na2S+S→Na2S2.

[0018] Preferably, the chemical reaction equation generated in the reactor in step S3 is as follows:

[0019]

[0020] or

[0021]

[0022] Preferably, in step S3, the temperature is controlled at 60-70°C, the heat preservation reaction time is 2h, the reaction degree is detected by gas chromatograph, and in step S4, the temperature is lowered to 35-45°C for liquid separation.

[0023] Preferably, in step S5, the vacuum distillation pressure is -0.095Ma, and the fractions are collected at 60-63°C to obtain 230.8g of diethyl disulfide, and the yield of the diethyl disulfide solution is 94.4%, the purity is greater than 99.8%, and the water content is less than 0.1%.

[0024] Preferably, in step S12, the temperature is heated to 50° C. and the reaction time is 1-3 hours. In step S12, as the reaction continues, the amount of suspended sulfur gradually decreases, the color of the solution gradually turns reddish brown, and the solution becomes transparent.

[0025] Preferably, in step S11, 200 mL of distilled water is added to a glass jacketed bottle, heated with circulating water, and then crystalline sodium sulfide is added and stirred to dissolve, thereby preparing a colorless sodium sulfide solution.

[0026] Preferably, the diethyl sulfate solution is prepared by using equal molecular weight ethanol and sulfuric acid. First, ethanol is put into a reaction kettle, and sulfuric acid is gradually dripped into the ethanol under stirring and cooling, and the reaction temperature is controlled to be less than 50°C. After the sulfuric acid is dripped, the temperature is controlled at 50-60°C for another 20 minutes. The reactant is added to a distiller and distilled under vacuum. The distillate is divided into upper and lower layers, the upper layer is a dilute solution of acid and ethanol, and the lower layer is diethyl sulfate. The sodium ethyl sulfate solution is prepared by dissolving sodium ethyl sulfate crystals in an ethanol solution.

[0027] Technical effects and advantages of the present invention:

[0028] (1) The present invention adds a sodium disulfide solution and a catalyst into a reactor, drips a sodium ethyl sulfate solution or a diethyl sulfate solution into the reactor, and performs a heat preservation reaction. After the reaction is completed, a mixed solution is obtained, and then the solution after the reaction is completed is cooled so that the solution is layered, wherein the lower layer is a sodium sulfate aqueous phase and the upper layer is an organic phase, i.e., a crude diethyl disulfide product. The reactor is then subjected to reduced pressure distillation, and the distillation gas is condensed and collected to obtain a colorless and transparent diethyl disulfide solution. The sodium disulfide solution and the sodium ethyl sulfate solution or the diethyl sulfate solution are used to react to ensure that the reaction is fully carried out, thereby improving the yield of the diethyl disulfide solution, and the upper layer of diethyl disulfide is purified by reduced pressure distillation to improve the purity of the diethyl disulfide solution. The lower layer of the reaction product sodium sulfate aqueous phase can be recycled again, thereby improving environmental protection.

[0029] (2) The present invention utilizes diethyl sulfate solution as a reaction raw material. The diethyl sulfate solution is prepared by reacting ethanol and sulfuric acid solution. The production process is simple, the raw materials are easy to obtain, the production cost is reduced, and the production efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1The figure is a schematic diagram of the preparation process of diethyl disulfide of the present invention.

[0031] Figure 2 The present invention is a schematic diagram of the preparation process of the sodium disulfide solution. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention provides Figure 1-2 A method for preparing diethyl disulfide shown comprises the following steps:

[0034] Step S1: preparing a sodium disulfide solution;

[0035] Step S2: adding raw materials, adding the sodium disulfide solution and 6.5 g of catalyst in step S1 into the reactor, and then dropping 308 g of the reactants into the reactor;

[0036] Step S3: reaction preparation, after the reactants are added dropwise, the reaction is kept warm, and the end of the reaction is observed by GC detection;

[0037] Step S4: Cooling and stratifying, wherein the solution after the reaction in step S3 is cooled to form stratified layers, wherein the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., crude diethyl disulfide;

[0038] Step S5: distillation and purification, by performing reduced pressure distillation on the reactor, condensing and collecting the distilled gas, to obtain a colorless and transparent diethyl disulfide solution.

[0039] The preparation of the sodium disulfide solution in step S1 comprises the following steps:

[0040] Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder;

[0041] Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating and keeping the solution warm, and then adding sulfur powder into the sodium sulfide solution, stirring and mixing;

[0042] Step S13: filtering and cooling. After the reaction is completed, the solution is filtered and cooled. The filtered solution is a sodium disulfide solution.

[0043] The reactant in step S2 is one of a diethyl sulfate solution and a sodium ethyl sulfate solution, and the catalyst is one or more of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400.

[0044] The chemical reaction equation generated in the reactor of step S12 is as follows:

[0045] Na2S+S→Na2S2.

[0046] The chemical reaction equation generated in the reactor of step S3 is as follows:

[0047]

[0048] or

[0049]

[0050] In step S3, the temperature is controlled at 60-70°C, the heat preservation reaction time is 2 hours, and the reaction degree is detected by gas chromatography. In step S4, the temperature is lowered to 35-45°C for liquid separation.

[0051] In step S5, the vacuum distillation pressure is -0.095Ma, and the fractions are collected at 60-63°C to obtain 230.8g of diethyl disulfide. The yield of the diethyl disulfide solution is 94.4%, the purity is greater than 99.8%, and the water content is less than 0.1%.

[0052] In step S12, the temperature is heated to 50° C., and the reaction time is 1-3 hours. In step S12, as the reaction continues, the amount of sulfur suspension gradually decreases, the color of the solution gradually turns reddish brown, and the solution becomes transparent.

[0053] In step S11, 200 mL of distilled water is added to a glass jacketed bottle, heated with circulating water, and then crystalline sodium sulfide is added and stirred to dissolve, thereby preparing a colorless sodium sulfide solution.

[0054] The diethyl sulfate solution is prepared by using equal molecular weight ethanol and sulfuric acid. First, ethanol is put into a reactor, and sulfuric acid is gradually dripped into the ethanol under stirring and cooling. The reaction temperature is controlled to be less than 50°C. After the sulfuric acid is dripped, the temperature is controlled at 50-60°C for another 20 minutes. The reactant is added to a distiller and distilled under vacuum. The distillate is divided into upper and lower layers. The upper layer is a dilute solution of acid and ethanol, and the lower layer is diethyl sulfate. The sodium ethyl sulfate solution is prepared by dissolving sodium ethyl sulfate crystals in an ethanol solution.

[0055] Embodiment 1

[0056] Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder;

[0057] Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating the temperature to 50° C., heating and keeping the solution warm, and then adding sulfur powder to the sodium sulfide solution, stirring and mixing, and the reaction time is 1-3 hours;

[0058] Step S13: filtering and cooling, after the reaction is completed, the solution is filtered and cooled, and the filtered solution is a sodium disulfide solution;

[0059] Step S2: adding raw materials, by adding the sodium disulfide solution and 6.5 g of catalyst in step S13 into the reactor, and dropping 308 g of diethyl sulfate solution into the reactor, wherein the catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400;

[0060] Step S3: Reaction preparation: after the diethyl sulfate solution is added dropwise, the reaction is carried out under heat preservation, the temperature is controlled at 60-70° C., the heat preservation reaction time is 2 h, and the completion of the reaction is observed by GC detection;

[0061] Step S4: Cooling and stratifying, wherein the solution after the reaction in step S3 is cooled to 35-45° C. for separation, so that the solution is stratified, the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., crude diethyl disulfide;

[0062] Step S5: purification by distillation, by performing reduced pressure distillation on the reactor, the reduced pressure distillation gas pressure is -0.095Ma, collecting fractions at 60-63°C, condensing and collecting the distilled gas, and obtaining a colorless and transparent diethyl disulfide solution.

[0063] The chemical reaction equation generated in the reactor of step S12 is as follows:

[0064] Na2S+S→Na2S2.

[0065] The chemical reaction equation generated in the reactor of step S3 is as follows:

[0066]

[0067] The diethyl disulfide prepared by the above method is a colorless transparent liquid with a yield of 94.4% and a purity of 99.8%.

[0068] Embodiment 2

[0069] Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder;

[0070] Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating the temperature to 50° C., heating and keeping the solution warm, and then adding sulfur powder to the sodium sulfide solution, stirring and mixing, and the reaction time is 1-3 hours;

[0071] Step S13: filtering and cooling, after the reaction is completed, the solution is filtered and cooled, and the filtered solution is a sodium disulfide solution;

[0072] Step S2: adding raw materials, by adding the sodium disulfide solution and 6.5 g of catalyst in step S13 into the reactor, and dropping 308 g of diethyl sulfate solution into the reactor, wherein the catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400;

[0073] Step S3: Reaction preparation: after the diethyl sulfate solution is added dropwise, the reaction is carried out under heat preservation, the temperature is controlled at 70-80° C., the heat preservation reaction time is 2 h, and the completion of the reaction is observed by GC detection;

[0074] Step S4: Cooling and stratifying, wherein the solution after the reaction in step S3 is cooled to 35-45° C. for separation, so that the solution is stratified, the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., crude diethyl disulfide;

[0075] Step S5: purification by distillation, by performing reduced pressure distillation on the reactor, the reduced pressure distillation gas pressure is -0.095Ma, collecting fractions at 60-63°C, condensing and collecting the distilled gas, and obtaining a colorless and transparent diethyl disulfide solution.

[0076] The chemical reaction equation generated in the reactor of step S12 is as follows:

[0077] Na2S+S→Na2S2.

[0078] The chemical reaction equation generated in the reactor of step S3 is as follows:

[0079]

[0080] The diethyl disulfide prepared by the above method is a colorless transparent liquid with a yield of 90.5% and a purity of 94.73.

[0081] Embodiment 3

[0082] Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder;

[0083] Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating the temperature to 50° C., heating and keeping the solution warm, and then adding sulfur powder to the sodium sulfide solution, stirring and mixing, and the reaction time is 1-3 hours;

[0084] Step S13: filtering and cooling, after the reaction is completed, the solution is filtered and cooled, and the filtered solution is a sodium disulfide solution;

[0085] Step S2: adding raw materials, by adding the sodium disulfide solution and 6.5 g of catalyst in step S13 into the reactor, and dropping 308 g of diethyl sulfate solution into the reactor, wherein the catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400;

[0086] Step S3: Reaction preparation: after the diethyl sulfate solution is added dropwise, the reaction is carried out under heat preservation, the temperature is controlled at 50-60° C., the heat preservation reaction time is 2 h, and the completion of the reaction is observed by GC detection;

[0087] Step S4: Cooling and stratifying, wherein the solution after the reaction in step S3 is cooled to 35-45° C. for separation, so that the solution is stratified, the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., crude diethyl disulfide;

[0088] Step S5: purification by distillation, by performing reduced pressure distillation on the reactor, the reduced pressure distillation gas pressure is -0.095Ma, collecting fractions at 60-63°C, condensing and collecting the distilled gas, and obtaining a colorless and transparent diethyl disulfide solution.

[0089] The chemical reaction equation generated in the reactor of step S12 is as follows:

[0090] Na2S+S→Na2S2.

[0091] The chemical reaction equation generated in the reactor of step S3 is as follows:

[0092]

[0093] The diethyl disulfide prepared by the above method is a colorless transparent liquid with a yield of 87.73% and a purity of 93.24%.

[0094] Embodiment 4

[0095] Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder;

[0096] Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating the temperature to 50° C., heating and keeping the solution warm, and then adding sulfur powder to the sodium sulfide solution, stirring and mixing, and the reaction time is 1-3 hours;

[0097] Step S13: filtering and cooling, after the reaction is completed, the solution is filtered and cooled, and the filtered solution is a sodium disulfide solution;

[0098] Step S2: adding raw materials, by adding the sodium disulfide solution and 6.5 g of catalyst in step S13 into the reactor, and dropping 308 g of sodium ethyl sulfate solution into the reactor, wherein the catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400;

[0099] Step S3: Reaction preparation: after the sodium ethyl sulfate solution is added dropwise, the reaction is carried out under heat preservation, the temperature is controlled at 60-70° C., the heat preservation reaction time is 2 h, and the completion of the reaction is observed by GC detection;

[0100] Step S4: Cooling and stratifying, wherein the solution after the reaction in step S3 is cooled to 35-45° C. for separation, so that the solution is stratified, the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., crude diethyl disulfide;

[0101] Step S5: purification by distillation, by performing reduced pressure distillation on the reactor, the reduced pressure distillation gas pressure is -0.095Ma, collecting fractions at 60-63°C, condensing and collecting the distilled gas, and obtaining a colorless and transparent diethyl disulfide solution.

[0102] The chemical reaction equation generated in the reactor of step S12 is as follows:

[0103] Na2S+S→Na2S2.

[0104] The chemical reaction equation generated in the reactor of step S3 is as follows:

[0105]

[0106] The diethyl disulfide prepared by the above method is a colorless transparent liquid with a yield of 94.1% and a purity of 99.2%.

[0107] Embodiment 5

[0108] Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder;

[0109] Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating the temperature to 50° C., heating and keeping the solution warm, and then adding sulfur powder to the sodium sulfide solution, stirring and mixing, and the reaction time is 1-3 hours;

[0110] Step S13: filtering and cooling, after the reaction is completed, the solution is filtered and cooled, and the filtered solution is a sodium disulfide solution;

[0111] Step S2: adding raw materials, by adding the sodium disulfide solution and 6.5 g of catalyst in step S13 into the reactor, and dropping 308 g of sodium ethyl sulfate solution into the reactor, wherein the catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400;

[0112] Step S3: Reaction preparation: after the sodium ethyl sulfate solution is added dropwise, the reaction is carried out under heat preservation, the temperature is controlled at 70-80° C., the heat preservation reaction time is 2 h, and the completion of the reaction is observed by GC detection;

[0113] Step S4: Cooling and stratifying, wherein the solution after the reaction in step S3 is cooled to 35-45° C. for separation, so that the solution is stratified, the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., crude diethyl disulfide;

[0114] Step S5: purification by distillation, by performing reduced pressure distillation on the reactor, the reduced pressure distillation gas pressure is -0.095Ma, collecting fractions at 60-63°C, condensing and collecting the distilled gas, and obtaining a colorless and transparent diethyl disulfide solution.

[0115] The chemical reaction equation generated in the reactor of step S12 is as follows:

[0116] Na2S+S→Na2S2.

[0117] The chemical reaction equation generated in the reactor of step S3 is as follows:

[0118]

[0119] The diethyl disulfide prepared by the above method is a colorless transparent liquid with a yield of 91.4% and a purity of 96.78%.

[0120] Embodiment 6

[0121] Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder;

[0122] Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating the temperature to 50° C., heating and keeping the solution warm, and then adding sulfur powder to the sodium sulfide solution, stirring and mixing, and the reaction time is 1-3 hours;

[0123] Step S13: filtering and cooling, after the reaction is completed, the solution is filtered and cooled, and the filtered solution is a sodium disulfide solution;

[0124] Step S2: adding raw materials, by adding the sodium disulfide solution and 6.5 g of catalyst in step S13 into the reactor, and dropping 308 g of sodium ethyl sulfate solution into the reactor, wherein the catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400;

[0125] Step S3: Reaction preparation: after the sodium ethyl sulfate solution is added dropwise, the reaction is carried out under heat preservation, the temperature is controlled at 50-60° C., the heat preservation reaction time is 2 h, and the completion of the reaction is observed by GC detection;

[0126] Step S4: Cooling and stratifying, wherein the solution after the reaction in step S3 is cooled to 35-45° C. for separation, so that the solution is stratified, the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., crude diethyl disulfide;

[0127] Step S5: purification by distillation, by performing reduced pressure distillation on the reactor, the reduced pressure distillation gas pressure is -0.095Ma, collecting fractions at 60-63°C, condensing and collecting the distilled gas, and obtaining a colorless and transparent diethyl disulfide solution.

[0128] The chemical reaction equation generated in the reactor of step S12 is as follows:

[0129] Na2S+S→Na2S2.

[0130] The chemical reaction equation generated in the reactor of step S3 is as follows:

[0131]

[0132] The diethyl disulfide prepared by the above method is a colorless transparent liquid with a yield of 89.12% and a purity of 92.80%.

[0133] It can be seen that the reaction temperature for preparing diethyl disulfide is preferably controlled at 60-70°C, which can obtain diethyl disulfide with higher yield and purity. The effect of temperature on the reaction is shown in the following table:

[0134]

[0135]

[0136] The working principle of the present invention is as follows: first, 1144 g of 15% sodium sulfide solution is weighed and added into a reaction kettle, the temperature is raised to 50° C., the solution is heated and kept warm, and then 64 g of sulfur powder is added into the sodium sulfide solution, the reaction time is 1-3 hours, and a sodium disulfide solution is obtained after filtering;

[0137] Then, the prepared sodium disulfide solution and 6.5 g of the catalyst are added to the reactor, and 308 g of sodium ethyl sulfate solution or diethyl sulfate solution is added dropwise to the reactor. After the sodium ethyl sulfate solution or the diethyl sulfate solution is added dropwise, the reaction is carried out under insulation, and the temperature is controlled to be 60-70° C. The insulation reaction time is 2 h. The reaction is observed to be complete by gas chromatography, and the solution after the reaction is completed is cooled to 35-45° C. for liquid separation, so that the solution is layered, the lower layer is a sodium sulfate aqueous phase, and the upper layer is an organic phase, i.e., a crude diethyl disulfide product;

[0138] Finally, the reactor was subjected to reduced pressure distillation, the pressure of which was -0.095 Ma, and fractions were collected at 60-63° C. The distilled gas was condensed and collected to obtain a colorless and transparent diethyl disulfide solution.

[0139] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing diethyl disulfide, characterized in that: The following steps are involved: Step S1: preparing a sodium disulfide solution; Step S2: adding raw materials, adding the sodium disulfide solution and 6.5 g of catalyst in step S1 into the reactor, and then dropping 308 g of the reactants into the reactor; Step S3: reaction preparation, after the reactants are added dropwise, the reaction is kept warm, and the end of the reaction is observed by GC detection; Step S4: cooling the solution after the reaction in step S3 so that the solution is separated into layers, wherein the lower layer is a sodium sulfate aqueous phase and the upper layer is an organic phase, i.e., crude diethyl disulfide; Step S5: distillation and purification, by performing reduced pressure distillation on the reactor, condensing and collecting the distilled gas, to obtain a colorless and transparent diethyl disulfide solution.

2. The method for preparing diethyl disulfide according to claim 1, characterized in that: The preparation of the sodium disulfide solution in step S1 comprises the following steps: Step S11: weighing raw materials, by weighing 1144 g of 15% sodium sulfide solution and 64 g of sulfur powder; Step S12: reaction preparation, by adding the sodium sulfide solution weighed in step S11 into a reaction kettle, heating and keeping the solution warm, and then adding sulfur powder to the sodium sulfide solution, stirring and mixing; Step S13: filtering and cooling. After the reaction is completed, the solution is filtered and cooled. The filtered solution is a sodium disulfide solution.

3. The method for preparing diethyl disulfide according to claim 1, characterized in that: The reactant in step S2 is one of a diethyl sulfate solution and a sodium ethyl sulfate solution, and the catalyst is one or more of tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, polyethylene glycol 600, and polyethylene glycol 400.

4. The method for preparing diethyl disulfide according to claim 2, characterized in that: The chemical reaction equation generated in the reactor of step S12 is as follows: Na2S+S→Na2S2.

5. The method for preparing diethyl disulfide according to claim 1, characterized in that: The chemical reaction equation generated in the reactor of step S3 is as follows: or 6. The method for preparing diethyl disulfide according to claim 1, characterized in that: In the step S3, the temperature is controlled at 60-70°C, the heat preservation reaction time is 2 hours, and the reaction degree is detected by gas chromatography. In the step S4, the temperature is lowered to 35-45°C for liquid separation.

7. The method for preparing diethyl disulfide according to claim 1, characterized in that: In the step S5, the vacuum distillation gas pressure is -0.095Ma, and the fractions are collected at 60-63°C to obtain 230.8g of diethyl disulfide. The yield of the diethyl disulfide solution is 94.4%, the purity is greater than 99.8%, and the water content is less than 0.1%.

8. The method for preparing diethyl disulfide according to claim 2, characterized in that: In the step S12, the temperature is heated to 50° C. and the reaction time is 1-3 hours. In the step S12, as the reaction continues, the amount of sulfur suspension gradually decreases, the color of the solution gradually turns reddish brown, and the solution becomes transparent.

9. The method for preparing diethyl disulfide according to claim 2, characterized in that: In the step S11, 200 mL of distilled water is added to a glass jacketed bottle, heated with circulating water, and then crystalline sodium sulfide is added and stirred to dissolve, thereby preparing a colorless sodium sulfide solution.

10. The method for preparing diethyl disulfide according to claim 3, characterized in that: The diethyl sulfate solution is prepared by using equal molecular weight ethanol and sulfuric acid. First, ethanol is put into a reaction kettle, and sulfuric acid is gradually dripped into the ethanol under stirring and cooling, and the reaction temperature is controlled to be less than 50°C. After the sulfuric acid is dripped, the temperature is controlled at 50-60°C for another 20 minutes. The reactant is added to a distiller and distilled under vacuum. The distillate is divided into upper and lower layers. The upper layer is a dilute solution of acid and ethanol, and the lower layer is diethyl sulfate. The sodium ethyl sulfate solution is prepared by dissolving sodium ethyl sulfate crystals in an ethanol solution.

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