Process for the preparation of disulfide pre-sulfiding agents and use of amino acids therein

Abstract

The application provides a preparation method of a disulfide pre-sulfurizing agent and application of an amino acid in the method. The amino acid is used as a catalyst, and the disulfide pre-sulfurizing agent with a yield not less than 95% and controllable molecular size can be prepared under normal temperature in an oxygen or air atmosphere. The reaction condition is more moderate, the energy consumption is smaller, the physical hazard is weaker, the health and environmental hazards are lower, and the method is beneficial to the use safety of equipment and prolongs the service life of the equipment in the pre-sulfurization process of a hydrogen sulfide agent.

Description

Technical Field

[0001] This invention belongs to the field of chemical safety technology, and particularly relates to the preparation method of disulfide pre-vulcanizing agents and the application of amino acids therein. Background Technology

[0002] The active components of hydrogenation catalysts are the sulfides of the effective metal components W, Mo, Ni, and Co. Only in the sulfide state do they exhibit high hydrogenation activity, stability, and selectivity. The pre-sulfurization process of the catalyst is the process of restoring its activity. Because sulfide-state catalysts readily undergo oxidation reactions with oxygen, fresh hydrogenation catalysts are transported and stored in their oxidized form. Hydrogenation catalysts are also in their oxidized form when first loaded into the reactor; therefore, pre-sulfurization is essential before use to restore their activity.

[0003] The pre-sulfurization process of hydrogenation catalysts involves the use of pre-sulfurizing agents. Currently, widely used pre-sulfurizing agents in industry include carbon disulfide, dimethyl sulfide, ethanethiol, dimethyl disulfide, thiophene, and butanethiol, all of which are organic sulfides. Common problems associated with these agents include:

[0004] 1. These pre-vulcanizing agents are highly flammable. Carbon disulfide, dimethyl sulfide, and ethanethiol all have flash points below -20°C, thiophene has a flash point of -6°C, and butanethiol has a flash point of 2°C. All of these pre-vulcanizing agents are classified as flammable liquids (Class 2). Dimethyl disulfide has a flash point of 25°C and is classified as flammable liquid (Class 3). These pre-vulcanizing agents may ignite and cause a fire when exposed to external stimuli such as open flames, high temperatures, or oxygen. Therefore, necessary safety measures should be taken when storing, using, and handling pre-vulcanizing agents to avoid mixing them with flammable substances and strictly prohibit violations of relevant regulations that could lead to a fire hazard. Their high flammability places high demands on the transportation and storage of pre-vulcanizing agents and also increases their usage costs.

[0005] 2. These substances pose significant health hazards, specifically manifested in toxicity, irritation, carcinogenicity, and allergic reactions. Toxicity refers to the fact that organosulfur compounds are toxic and can harm the human body through inhalation, ingestion, or skin contact. Irritation refers to the fact that organosulfur compounds can irritate the eyes, skin, and respiratory tract; long-term exposure to organosulfur compounds may lead to chronic lung disease, dermatitis, and other diseases. Carcinogenicity refers to the fact that some organosulfur compounds are carcinogenic, and long-term exposure to these substances may increase the risk of cancer. Allergic reactions refer to the fact that some people may experience allergic reactions to organosulfur compounds, such as rashes, shortness of breath, and throat swelling. Therefore, existing pre-sulfurizing agents pose a high safety risk during use and are prone to causing safety accidents, thus necessitating the research and development of new pre-sulfurizing agents.

[0006] However, existing pre-vulcanizing agent development routes each have their drawbacks:

[0007] 1. The pre-sulfurization agent product is a mixture. Existing methods often use small molecule olefins such as propylene, butene, and 2-butene to react with sulfur to form a mixture of small molecule thiols and thioethers. Because there are differences in activity between different sulfides, the reaction conditions of mixed sulfides are difficult to control accurately during the pre-sulfurization process of hydrogenation catalysts, which poses a risk to the safety of equipment use and shortens the service life of equipment.

[0008] 2. The pre-vulcanizing agent product is a small-molecule organic sulfide. As mentioned above, small-molecule organic sulfides are highly flammable and pose significant health and environmental hazards, which places high demands on the transportation and storage of pre-vulcanizing agents.

[0009] 3. The reaction conditions are relatively harsh. The generation of traditional pre-vulcanizing agents usually requires high temperature and high pressure reaction conditions (generally 200℃, 3-6MPa), and specific reaction vessels or equipment are required to complete the synthesis of pre-vulcanizing agents, and the energy consumption is relatively large.

[0010] Therefore, there is an urgent need to develop a method for synthesizing pre-vulcanizing agents with milder reaction conditions, no hazardous waste, and selectively low physical hazards. Summary of the Invention

[0011] In view of the various shortcomings of existing pre-vulcanizing agent development routes, the purpose of this invention is to provide a method for preparing pre-vulcanizing agents that has mild reaction conditions, does not generate hazardous waste, and allows for selective synthesis of agents with low physical hazards.

[0012] To achieve the above objectives, the first aspect of the present invention provides the application of amino acids as catalysts in the preparation of disulfide pre-sulfurizing agents by catalyzing the reaction of mercapto-containing organic sulfides.

[0013] According to one specific embodiment of the present invention, the amino acid is selected from at least one of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, threonine, aspartic acid, glutamic acid, lysine, arginine, ornithine, and histidine.

[0014] According to a specific embodiment of the present invention, the mercapto-containing organic sulfide is a thiol compound, a thiophenol compound, or a thiophene compound containing a mercapto group.

[0015] According to one specific embodiment of the present invention, the thiol compound includes one of C2-C8 alkyl thiols, cyclohexyl thiols, and benzyl thiols;

[0016] Preferably, the C2-C8 alkyl thiols include one of butanethiol, propanethiol, isobutanethiol, tert-butanethiol, n-octanethiol, ethanethiol, and hexanethiol.

[0017] According to one specific embodiment of the present invention, the thiophenolic compound includes benzenethiophenol or methylbenzenithiophenol;

[0018] Preferably, the methylthiophenol is 2-methylthiophenol or 4-methylthiophenol.

[0019] According to a specific embodiment of the present invention, the thiophene compound containing a mercapto group is 2-mercaptothiophene or 3-mercaptothiophene.

[0020] A second aspect of the present invention provides a method for preparing a disulfide-based pre-vulcanizing agent according to the first aspect of the present invention, comprising the following steps:

[0021] The thiol-containing organic sulfides are reacted under the catalysis of the amino acids to produce the disulfide pre-sulfurizing agent.

[0022] According to one specific embodiment of the present invention, the reaction is carried out in a protic solvent.

[0023] According to one specific embodiment of the present invention, the concentration of the mercapto-containing organic sulfide in the protic solvent is 0.1-6.25 mol / L.

[0024] According to one specific embodiment of the present invention, the amount of the amino acid used is 10%-50% of the equivalent of the mercapto-containing organic sulfide.

[0025] According to one specific embodiment of the present invention, the protic solvent is selected from at least one of water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol.

[0026] According to one specific embodiment of the present invention, the reaction temperature is room temperature; and / or the reaction duration is 0.5-12 h;

[0027] Preferably, the reaction is carried out in an oxygen or air atmosphere.

[0028] According to a specific embodiment of the present invention, after the reaction is completed, a post-reaction solution containing the disulfide pre-sulfurizing agent is obtained;

[0029] Preferably, an organic solvent is used as the eluent to separate the reaction solution by passing it through a silica gel column, wherein the amino acids are adsorbed by the silica gel column, and the disulfide pre-sulfurizing agent is eluted into the eluent; the eluent is then subjected to vacuum distillation to remove the protic solvent and the eluent, yielding the disulfide pre-sulfurizing agent; or

[0030] The solution after the reaction was directly subjected to vacuum distillation, and the fraction was collected to obtain the disulfide pre-sulfurizing agent;

[0031] Preferably, the organic solvent is methanol or ethanol.

[0032] The third aspect of the present invention provides a disulfide pre-vulcanizing agent prepared by the method described in the second aspect of the present invention.

[0033] The application of the disulfide presulfurizing agent prepared by the method described in the second aspect of the present invention or the disulfide presulfurizing agent described in the third aspect of the present invention in the presulfurization of hydrogenation catalysts.

[0034] The beneficial effects of this invention are:

[0035] To address the shortcomings of existing pre-sulfurizing agent development routes, such as the pre-sulfurizing agent products being mixtures, the difficulty in accurately controlling reaction conditions during hydrogenation catalyst pre-sulfurization, the pre-sulfurizing agent products being small-molecule organic sulfides with high flammability, health and environmental hazards, harsh reaction conditions, and high energy consumption, this invention provides a method for preparing disulfide-based pre-sulfurizing agents and the application of amino acids in them.

[0036] Compared with the prior art, the present invention has at least the following advantages:

[0037] 1. This invention uses amino acids as catalysts to prepare disulfide pre-sulfurizing agents in an oxygen (or air) atmosphere at room temperature, with milder reaction conditions and lower energy consumption;

[0038] 2. This invention uses amino acids as catalysts to catalyze the reaction of mercapto-containing organic sulfides to prepare a disulfide pre-sulfurizing agent with a yield of not less than 95%. The disulfide pre-sulfurizing agent has high purity, unlike the general mixed products of the prior art. Under the pre-sulfurization effect of the disulfide pre-sulfurizing agent, the reaction conditions are easier to control during the subsequent hydrogenation catalyst sulfurization process to achieve the ideal sulfurization effect, and coking residue is also avoided, which is beneficial to the safety of equipment use and extends the service life of the equipment.

[0039] 3. This invention uses amino acids as catalysts to catalyze the reaction of mercapto-containing organic sulfides, enabling selective control of the preparation of small-molecule and large-molecule disulfide pre-sulfurizing agents, with weaker physical hazards and lower health and environmental risks. Attached Figure Description

[0040] Figure 1 A schematic diagram of the reaction equation for the preparation method of disulfide pre-vulcanizing agent provided by the present invention.

[0041] Figure 2 This is a schematic diagram illustrating the catalytic mechanism of the application of amino acids provided by the present invention in the preparation of pre-sulfurizing agents using thiol-containing organic sulfides as raw materials.

[0042] Figure 1 , Figure 2 In the middle, R1 represents Figure 1 China and Figure 2 The lower half shows the group not shown in the structure of the mercapto-containing organosulfur compound; R2 represents... Figure 2 The groups not shown in the structure of the amino acids shown in the upper part.

[0043] Figure 3 The 1H NMR spectrum of the reaction product obtained in Example 23.

[0044] Figure 4 The image shows the carbon NMR spectrum of the reaction product obtained in Example 23.

[0045] Figure 5 The 1H NMR spectrum of the reaction product obtained in Example 25.

[0046] Figure 6 The image shows the carbon NMR spectrum of the reaction product obtained in Example 25.

[0047] Figure 7 The 1H NMR spectrum of the reaction product obtained in Example 26.

[0048] Figure 8 The image shows the carbon NMR spectrum of the reaction product obtained in Example 26.

[0049] Figures 9 to 11 The UV-Vis absorption spectrum of the reaction system measured during the reaction process in Example 25 is shown.

[0050] Figure 12 The UV-Vis absorption spectra of the reaction system measured at time points of 0 min and 10 min during the reaction process of Comparative Example 1 are shown. Detailed Implementation

[0051] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0052] Amino acids contain both amino and carboxyl groups in their structure, forming a zwitterionic structure in protic solvents. Through extensive research, the inventors discovered that in an oxygen or air atmosphere, when amino acids and thiol-containing organosulfur compounds coexist in a protic solvent, this zwitterionic structure formed by the amino acid can form hydrogen bonds with the thiol groups of the thiol-containing organosulfur compound and oxygen, resulting in a structure like... Figure 2 The intermediate shown eventually dehydrates to form a disulfide structure. In this process, the amino acid acts as a catalyst, catalyzing the dehydrogenation of two units of thiol-containing organic sulfides to form disulfide compounds. Based on the above, the inventors completed this invention.

[0053] This invention provides the application of amino acids as catalysts to catalyze the reaction of thiol-containing organic sulfides to prepare disulfide pre-sulfurizing agents.

[0054] Optionally, the amino acid is selected from at least one of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, threonine, aspartic acid, glutamic acid, lysine, arginine, ornithine, and histidine.

[0055] Optionally, the amino acid is selected from at least one of L-arginine, glycine, L-aspartic acid, L-lysine, glutamic acid, ornithine, and L-serine.

[0056] Optionally, the mercapto-containing organic sulfide is a thiol compound, a thiophenol compound, or a thiophene compound containing a mercapto group.

[0057] Optionally, the thiol compound includes one of C2-C8 alkyl thiols, cyclohexyl thiols, and benzyl thiols.

[0058] Optionally, the C2-C8 alkyl thiols include one of butanethiol, propanethiol, isobutanethiol, tert-butanethiol, n-octanethiol, ethanethiol, and hexanethiol.

[0059] Optionally, the thiophenolic compound includes benzenethiophenol or methylbenzenethiophenol.

[0060] Optionally, the methylthiophenol is 2-methylthiophenol or 4-methylthiophenol.

[0061] Optionally, the thiophene compound containing a mercapto group is 2-mercaptothiophene or 3-mercaptothiophene.

[0062] Optionally, depending on the type of the mercapto-containing organic sulfide, the disulfide pre-curing agent is one of dibutyl disulfide, bis(2-thienyl) disulfide, dipropyl disulfide, bis(3-thienyl) disulfide, diisobutyl disulfide, dihexyl disulfide, dicyclohexyl disulfide, ditert-butyl disulfide, dibenzyl disulfide, dioctyl disulfide, diethyl disulfide, diphenyl disulfide, di(2-tolyl) disulfide, and di(4-tolyl) disulfide.

[0063] This invention provides a method for preparing a disulfide-based pre-vulcanizing agent according to an embodiment of the invention, comprising the following steps:

[0064] The thiol-containing organic sulfides are reacted under the catalysis of the amino acids to produce the disulfide pre-sulfurizing agent.

[0065] Optionally, the reaction is carried out in a protic solvent.

[0066] Optionally, the concentration of the mercapto-containing organic sulfide in the protic solvent is 0.1-6.25 mol / L.

[0067] Optionally, the concentration of the mercapto-containing organic sulfide in the protic solvent is any value from 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.3 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, and 6.25 mol / L, or any value within a range of any two of these values.

[0068] Optionally, the amount of the amino acid used is 10%-50% of the equivalent of the thiol-containing organosulfur compound.

[0069] Optionally, the amount of the amino acid is any value from 10%, 15%, 17%, 20%, 25%, 30%, 35%, 40%, 45%, 50% of the equivalent of the mercapto-containing organosulfur compound, or any value within a range of any two of these values.

[0070] The phrase "the amount of amino acid is 10%-50% of the equivalent of the mercapto-containing organosulfur compound" in this invention is understood as follows: the amount of the mercapto-containing organosulfur compound is 100%, and the percentage of the amount of the amino acid is 10%-50%.

[0071] Optionally, the protic solvent is selected from at least one of water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol.

[0072] Optionally, the protic solvent is selected from water, methanol, or ethanol.

[0073] Optionally, the reaction is carried out at room temperature and / or for 0.5-12 hours.

[0074] Optionally, the reaction duration is any value from 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h, and 12h, or any value within a range of any two values.

[0075] Optionally, the reaction is carried out in an oxygen or air atmosphere.

[0076] Optionally, after the reaction is completed, a post-reaction solution containing the disulfide-based pre-sulfurizing agent is obtained.

[0077] Optionally, an organic solvent is used as the eluent to separate the reaction solution by passing it through a silica gel column, wherein the amino acids are adsorbed by the silica gel column, and the disulfide pre-sulfurizing agent is eluted into the eluent; the eluent is then subjected to vacuum distillation to remove the protic solvent and the eluent, yielding the disulfide pre-sulfurizing agent; or

[0078] The solution after the reaction is directly subjected to vacuum distillation, and the fraction is collected to obtain the disulfide pre-sulfurizing agent.

[0079] Optionally, the organic solvent is methanol or ethanol.

[0080] This invention provides a disulfide pre-sulfurizing agent prepared by the method described in this invention.

[0081] The application of any one of the disulfide presulfurizing agents prepared by the method described in the embodiments of the present invention, or any one of the disulfide presulfurizing agents described in the embodiments of the present invention, in the presulfurization of hydrogenation catalysts.

[0082] In this invention, room temperature refers to 25°C.

[0083] Example 1

[0084] Add 90g of butanethiol to the reactor as a reaction raw material, add 200mL of methanol as a protic solvent to the reaction raw material, and add 10% equivalent of L-arginine as a catalyst to form a reaction system.

[0085] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 2 hours. Butyl mercaptan was dehydrogenated under the action of L-arginine to form a disulfide bond, resulting in a reaction solution containing dibutyl disulfide.

[0086] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-arginine was adsorbed by the silica gel column. After elution, the methanol was removed by vacuum distillation to obtain 85g of dibutyl disulfide (colorless liquid), with a yield of 96%.

[0087] Example 2

[0088] 116g of 3-mercaptothiophene was added to the reaction vessel as a reaction raw material, 300mL of ethanol was added as a protic solvent, and 10% equivalent of glycine was added as a catalyst to form the reaction system.

[0089] The reaction system was placed in an air atmosphere and stirred at room temperature for 6 hours. Under the action of glycine, 3-mercaptothiophene was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing bis(3-thiophene) disulfide.

[0090] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, glycine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove ethanol and methanol, yielding 110 g of bis(3-thienyl)disulfide (pale yellow solid), with a yield of 96%.

[0091] Example 3

[0092] Add 450g of butanethiol to the reaction vessel as a reaction raw material, add 1000mL of water as a protic solvent to the reaction raw material, and add L-aspartic acid (10% of the reaction raw material equivalent) as a catalyst to form the reaction system.

[0093] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 8 hours. Butylthiol was dehydrogenated under the action of L-aspartic acid to form a disulfide bond, resulting in a reaction solution containing dibutyl disulfide.

[0094] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-aspartic acid was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 440 g of dibutyl disulfide (colorless liquid), with a yield of 99%.

[0095] Example 4

[0096] Add 380g of propanethiol to the reactor as a reaction raw material, add 800mL of water as a protic solvent to the reaction raw material, and add L-arginine (equivalent to 20% of the reaction raw material) as a catalyst to form the reaction system.

[0097] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 3.5 hours. Under the action of L-arginine, propanethiol was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing dipropyl disulfide.

[0098] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-arginine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove methanol and water, yielding 368 g of dipropyl disulfide (colorless liquid), with a yield of 98%.

[0099] Example 5

[0100] 116g of 2-mercaptothiophene was added to the reaction vessel as a reaction raw material, 400mL of water was added as a protic solvent, and 15% equivalent of L-lysine was added as a catalyst to form the reaction system.

[0101] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 6 hours. Under the action of L-lysine, 2-mercaptothiophene was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing bis(2-thiophene) disulfide.

[0102] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-lysine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 111.6 g of bis(2-thienyl)disulfide (pale yellow solid), with a yield of 97%.

[0103] Example 6

[0104] 90g of isobutyl mercaptan was added to the reactor as a reaction raw material, 250mL of water was added as a protic solvent, and L-arginine (10% of the equivalent of the reaction raw material) was added as a catalyst to form the reaction system.

[0105] The reaction system was placed in an air atmosphere and stirred at room temperature for 2 hours. Isobutyl mercaptan was dehydrogenated under the action of L-arginine to form a disulfide bond, resulting in a reaction solution containing diisobutyl disulfide.

[0106] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-arginine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 85 g of diisobutyl disulfide (colorless liquid), with a yield of 96%.

[0107] Example 7

[0108] 118g of hexamethylenetetramine was added to the reactor as a reaction raw material, 200mL of water was added as a protic solvent, and L-aspartic acid (10% of the equivalent of the reaction raw material) was added as a catalyst to form the reaction system.

[0109] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 4 hours. Hexylthiol was dehydrogenated under the action of L-aspartic acid to form a disulfide bond, resulting in a reaction solution containing dihexyl disulfide.

[0110] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-aspartic acid was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 112 g of dihexyl disulfide (colorless liquid), with a yield of 96%.

[0111] Example 8

[0112] 116g of cyclohexanethiol was added to the reactor as a reaction raw material, 200mL of methanol was added as a protic solvent, and glutamic acid (equivalent to 17% of the reaction raw material) was added as a catalyst to obtain the reaction system.

[0113] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 3.5 hours. Cyclohexyl mercaptan was dehydrogenated under the action of glutamic acid to form a disulfide bond, resulting in a reaction solution containing dicyclohexyl disulfide.

[0114] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, glutamic acid was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove methanol, yielding 110 g of dicyclohexyl disulfide (colorless liquid), with a yield of 96%.

[0115] Example 9

[0116] 900g of tert-butyritin was added to the reactor as a reaction raw material, 2000mL of water was added as a protic solvent, and 20% of the reaction raw material equivalent of ornithine was added as a catalyst to obtain the reaction system.

[0117] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 9 hours. Under the action of ornithine, tert-butyl mercaptan was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing di-tert-butyl disulfide.

[0118] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. Ornithine was adsorbed by the silica gel column during the elution process. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 879 g of di-tert-butyl disulfide (colorless liquid), with a yield of 99%.

[0119] Example 10

[0120] 620g of benzyl mercaptan was added to the reactor as a reaction raw material, 1500mL of methanol was added as a protic solvent, and 10% equivalent of L-serine was added as a catalyst to obtain the reaction system.

[0121] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 6 hours. Under the action of L-serine, benzyl thiol was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing dibenzyl disulfide.

[0122] The reaction solution was separated by passing it through a silica gel column with ethanol as the eluent. During the elution process, L-serine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove methanol and ethanol, yielding 598 g of dibenzyl disulfide (white solid), with a yield of 97%.

[0123] Example 11

[0124] 14.6 g of n-octyl mercaptan was added to the reactor as a reaction raw material, 1000 mL of n-propanol was added as a protic solvent, and 12.5% ​​equivalent of alanine was added as a catalyst to form the reaction system.

[0125] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 0.5 hours. Under the action of alanine, n-octyl mercaptan was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing dioctyl disulfide.

[0126] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, alanine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove n-propanol and methanol, yielding 14 g of dioctyl disulfide (colorless liquid), with a yield of 97%.

[0127] Example 12

[0128] Add 31g of ethanethiol to the reactor as a reaction raw material, add 200mL of isopropanol as a protic solvent to the reaction raw material, and add 21% equivalent of valine as a catalyst to form a reaction system.

[0129] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 1 hour. Ethyl mercaptan was dehydrogenated under the action of valine to form a disulfide bond, resulting in a reaction solution containing diethyl disulfide.

[0130] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, valine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove isopropanol and methanol, yielding 29 g of diethyl disulfide (colorless liquid), with a yield of 95%.

[0131] Example 13

[0132] 16.5g of thiophenol was added to the reactor as a reaction raw material, 300mL of n-butanol was added as a protic solvent, and 22.5% equivalent of leucine was added as a catalyst to form the reaction system.

[0133] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 1.5 hours. Benzothiophenol was dehydrogenated under the action of leucine to form a disulfide bond, resulting in a reaction solution containing diphenyl disulfide.

[0134] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, leucine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove n-butanol and methanol, yielding 15.5 g of diphenyl disulfide product (white solid), with a yield of 95%.

[0135] Example 14

[0136] 49.6 g of 2-methylthiophenol was added to the reactor as a reaction raw material, 400 mL of isobutanol was added as a protic solvent, and 25% equivalent of isoleucine was added as a catalyst to form the reaction system.

[0137] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 2.5 hours. Under the action of isoleucine, 2-methylthiophenol was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing 2-tolyl disulfide.

[0138] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, isoleucine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove isobutanol and methanol, yielding 47.3 g of di(2-tolyl)disulfide product (pale yellow solid), with a yield of 96%.

[0139] Example 15

[0140] 67.6 g of butanethiol was added to the reactor as a reaction raw material, 500 mL of tert-butanol was added as a protic solvent, and 27.5% equivalent of methionine was added as a catalyst to form the reaction system.

[0141] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 3 hours. Butyl mercaptan was dehydrogenated under the action of methionine to form a disulfide bond, resulting in a reaction solution containing dibutyl disulfide.

[0142] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, methionine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove tert-butanol and methanol, yielding 65g of dibutyl disulfide (colorless liquid) with a yield of 97%.

[0143] Example 16

[0144] 91.4g of propanethiol was added to the reactor as a reaction raw material, 600mL of water was added as a protic solvent, and 30% equivalent of proline was added as a catalyst to form the reaction system.

[0145] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 4.5 hours. Under the action of proline, propanethiol was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing dipropyl disulfide.

[0146] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, proline was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 89.2 g of dipropyl disulfide (colorless liquid), with a yield of 99%.

[0147] Example 17

[0148] 157.8g of isobutyl mercaptan was added to the reactor as a reaction raw material, 700mL of methanol was added as a protic solvent, and 32.5% equivalent of tryptophan was added as a catalyst to form the reaction system.

[0149] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 5 hours. Isobutyl mercaptan was dehydrogenated under the action of tryptophan to form a disulfide bond, resulting in a reaction solution containing diisobutyl disulfide.

[0150] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, tryptophan was adsorbed by the silica gel column. After elution, the methanol was removed by vacuum distillation to obtain 150 g of diisobutyl disulfide (colorless liquid), with a yield of 96%.

[0151] Example 18

[0152] 216.4 g of tert-butyritin was added to the reactor as a reaction raw material, 800 mL of ethanol was added as a protic solvent, and 35% equivalent of tyrosine was added as a catalyst to form the reaction system.

[0153] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 5.5 hours. Under the action of tyrosine, tert-butyl mercaptan was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing di-tert-butyl disulfide.

[0154] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, tyrosine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove ethanol and methanol, yielding 206 g of di-tert-butyl disulfide (colorless liquid), with a yield of 96%.

[0155] Example 19

[0156] 460.8 g of n-octyl mercaptan was added to the reactor as a reaction raw material, 900 mL of n-propanol was added as a protic solvent, and 37.5% equivalent of cysteine ​​was added as a catalyst to form the reaction system.

[0157] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 6.5 hours. Under the action of cysteine, n-octyl mercaptan was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing dioctyl disulfide.

[0158] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, cysteine ​​was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove n-propanol and methanol, yielding 438 g of dioctyl disulfide (colorless liquid), with a yield of 96%.

[0159] Example 20

[0160] 248.5g of ethanethiol was added to the reactor as a reaction raw material, 1000mL of isopropanol was added as a protic solvent, and 40% equivalent of phenylalanine was added as a catalyst to form the reaction system.

[0161] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 7.5 hours. Ethyl mercaptan was dehydrogenated under the action of phenylalanine to form a disulfide bond, resulting in a reaction solution containing diethyl disulfide.

[0162] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, phenylalanine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove isopropanol and methanol, yielding 234 g of diethyl disulfide (colorless liquid), with a yield of 96%.

[0163] Example 21

[0164] Add 638.5g of hexamethylenetetramine as a reaction raw material to the reactor, add 1200mL of n-butanol as a protic solvent to the reaction raw material, and add 42.5% equivalent of L-aspartic acid as a catalyst to form the reaction system.

[0165] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 8.5 hours. Under the action of L-aspartic acid, hexylthiol was dehydrogenated to form a disulfide bond, resulting in a reaction solution containing dihexyl disulfide.

[0166] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-aspartic acid was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove n-butanol and methanol, yielding 621g of dihexyl disulfide (colorless liquid), with a yield of 98%.

[0167] Example 22

[0168] 813.6 g of cyclohexanethiol was added to the reactor as a reaction raw material, 1400 mL of isobutanol was added as a protic solvent, and 45% equivalent of glutamic acid was added as a catalyst to form the reaction system.

[0169] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 9.5 hours. Cyclohexyl mercaptan was dehydrogenated under the action of glutamic acid to form a disulfide bond, resulting in a reaction solution containing dicyclohexyl disulfide.

[0170] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, glutamic acid was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove isobutanol and methanol, yielding 794 g of dicyclohexyl disulfide (colorless liquid), with a yield of 99%.

[0171] Example 23

[0172] 1093g of benzyl mercaptan was added to the reactor as a reaction raw material, 2600mL of tert-butanol was added as a protic solvent, and 47.5% equivalent of threonine was added as a catalyst to form the reaction system.

[0173] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 10 hours. Benzyl thiol was dehydrogenated under the action of threonine to form a disulfide bond, yielding a post-reaction solution containing dibenzyl disulfide.

[0174] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, threonine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove tert-butanol and methanol, yielding 1035g of dibenzyl disulfide product (pale yellow solid), with a yield of 96%.

[0175] Example 24

[0176] 1189.9g of thiophenol was added to the reactor as a reaction raw material, 4800mL of water was added as a protic solvent, and histidine (50% equivalent of the reaction raw material) was added as a catalyst to form the reaction system.

[0177] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 12 hours. Benzothiophenol was dehydrogenated under the action of histidine to form a disulfide bond, resulting in a reaction solution containing diphenyl disulfide.

[0178] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, histidine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 1150 g of diphenyl disulfide product (white solid), with a yield of 98%.

[0179] Example 25

[0180] 220g of thiophenol was added to the reactor as a reaction raw material, 1400mL of water was added as a protic solvent, and 40% equivalent of L-arginine was added as a catalyst to form the reaction system.

[0181] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 3.5 hours. Under the action of L-arginine, thiophene dehydrogenated to form a disulfide bond, yielding a post-reaction solution containing diphenyl disulfide.

[0182] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-arginine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 214 g of diphenyl disulfide product (white solid), with a yield of 98%.

[0183] Example 26

[0184] 620g of 4-methylthiophenol was added to the reactor as a reaction raw material, 3200mL of water was added as a protic solvent, and 35% equivalent of L-arginine was added as a catalyst to form the reaction system.

[0185] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 3 hours. Under the action of L-arginine, thiophene was dehydrogenated to form a disulfide bond, resulting in a post-reaction solution containing di(4-tolyl)disulfide.

[0186] The reaction solution was separated by passing it through a silica gel column with methanol as the eluent. During the elution process, L-arginine was adsorbed by the silica gel column. After elution, the solution was distilled under reduced pressure to remove water and methanol, yielding 610 g of di(4-tolyl)disulfide product (white solid), with a yield of 99%.

[0187] Comparative Example 1

[0188] 220.0g of thiophenol was added to the reactor as a reaction raw material, and 1400mL of water was added to the reaction raw material as a protic solvent to form a reaction system.

[0189] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 12 hours. The extent of the reaction was monitored by thin-layer chromatography (ethyl acetate: petroleum ether = 1:4), and no new substances were observed to be formed.

[0190] Comparative Example 2

[0191] 109.3g of benzyl mercaptan was added to the reactor as a reaction raw material, and 260mL of tert-butanol was added to the reaction raw material as a protic solvent to form the reaction system.

[0192] The reaction system was placed in an air atmosphere and stirred at room temperature for 12 hours. The extent of the reaction was monitored by thin-layer chromatography (ethyl acetate: petroleum ether = 1:10), and no new substances were observed to be formed.

[0193] Comparative Example 3

[0194] 116g of 2-mercaptothiophene was added to the reaction vessel as a reaction raw material, and 400mL of water was added to the reaction raw material as a protic solvent to form the reaction system.

[0195] The reaction system was placed in an oxygen atmosphere and stirred at room temperature for 6 hours. The extent of the reaction was monitored by thin-layer chromatography (methanol: petroleum ether = 1:10), and no new substances were observed to be formed.

[0196] Test Example 1

[0197] Taking Examples 23, 25, and 26 as examples, the reaction products obtained by vacuum distillation were subjected to 1H NMR and 1C NMR spectra (using CDCl3 as solvent) to characterize the product structure, specifically as follows: Figures 3 to 8 As shown.

[0198] Figure 3 The 1H NMR spectrum of the reaction product obtained in Example 23: 1H NMR (CDCl3, 300MHz): δ7.39-7.26 (10H, m), 3.64 (4H, s).

[0199] Figure 4 The carbon NMR spectrum of the reaction product obtained in Example 23: 13 C NMR (CDCl3, 75.4MHz); δ 137.8, 129.8, 128.9, 127.8 and 43.7.

[0200] Figure 5 The 1H NMR spectrum of the reaction product obtained in Example 25: 1 H NMR (CDCl3, 300MHz): δ7.55-7.52(4H,m), 7.36-7.25(6H,m).

[0201] Figure 6 The carbon NMR spectrum of the reaction product obtained in Example 25: 13 C NMR (CDCl3, δ 75.4 MHz); 137.5, 129.5, 128.0 and 127.6.

[0202] Figure 7 The 1H NMR spectrum of the reaction product obtained in Example 26: 1 H NMR (CDCl3, 300MHz): δ7.44 (4H,d,J=8.19Hz), 7.15 (4H,d,J=7.97Hz), 2.35 (6H,s).

[0203] Figure 8 The carbon NMR spectrum of the reaction product obtained in Example 26: 13 C NMR (CDCl3, 75.4 MHz); δ 137.9, 134.3, 130.2, 129.0 and 21.5.

[0204] Depend on Figures 3 to 8 It can be seen that the reaction products obtained in Examples 23, 25 and 26 are, in order: dibenzyl disulfide, diphenyl disulfide and di(4-tolyl) disulfide.

[0205] It should be noted that the 1H NMR and 1C NMR spectra of the reaction products obtained in Examples 1 to 22 and 24 show that the corresponding disulfide pre-sulfurizing agents were prepared in Examples 1 to 22 and 24.

[0206] Test Example 2

[0207] Compared to Examples 25, 23, and 5, as described in Comparative Examples 1, 2, and 3, without the addition of L-arginine, threonine, or L-lysine, thin-layer chromatography monitoring of the reaction progress revealed no new product formation. This indicates that in the absence of amino acid catalysis, thiophenol, benzyl thiol, or 2-mercaptothiophene cannot react to produce disulfide compounds. To further illustrate the catalytic role of amino acids in the reaction of thiol-containing organic sulfides to form disulfide compounds, Examples 25 and 1 are used as examples. Ultraviolet-visible absorption spectroscopy was used to monitor the changes in components within the reaction system during the reaction process. The results are as follows: Figures 9 to 12 As shown.

[0208] Figures 9 to 11 This is the result of superimposing the UV-Vis absorption spectra of the substances involved in the reaction in Example 25. Figure 9 This indicates that the spectrum of the mixed system of thiophenol and L-arginine is not a superposition of the individual spectra of thiophenol and L-arginine, suggesting that thiophenol reacts with L-arginine to form an intermediate. Figure 10 This indicates that as the reaction time is extended to 20 min, the peak intensity of the intermediate decreases, suggesting that its content is reduced and it is gradually consumed as the reaction proceeds. Figure 11 This indicates that the UV absorption spectrum of the system no longer changes after 360 minutes of reaction, indicating that the reaction has ended.

[0209] Figure 12 The UV-Vis absorption spectra of the reaction system in Comparative Example 1 are shown at time points of 0 min and 10 min. It can be seen that the UV-Vis absorption spectrum measured at 0 min is the spectrum of the starting material, thiophenol; the spectrum of the reaction system measured at 10 min overlaps with the spectrum of thiophenol at 0 min, proving that at 10 min, the reaction system of Comparative Example 1 still contains only thiophenol, with no product formed.

[0210] contrast Figures 9 to 11 and Figure 12 It is known that L-arginine has a catalytic effect on the reaction of thiophene to form diphenyl disulfide.

[0211] In summary, amino acids act as catalysts to catalyze the reaction of thiol-containing organic sulfides to generate disulfide pre-sulfurizing agents.

[0212] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. Application of amino acids as catalysts in the preparation of disulfide pre-sulfurizing agents by catalyzing the reaction of mercapto-containing organic sulfides.

2. The application according to claim 1, characterized in that, The amino acid is selected from at least one of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, threonine, aspartic acid, glutamic acid, lysine, arginine, ornithine, and histidine.

3. The application according to claim 1 or 2, characterized in that, The thiol-containing organic sulfides are thiols, thiophenols, or thiophenes containing thiol groups.

4. The application according to claim 3, characterized in that, The thiols include one of C2-C8 alkyl thiols, cyclohexyl thiols, and benzyl thiols; Preferably, the C2-C8 alkyl thiols include one of butanethiol, propanethiol, isobutanethiol, tert-butanethiol, n-octanethiol, ethanethiol, and hexanethiol.

5. The application according to claim 3, characterized in that, The thiophenolic compounds include benzenethiophenol or methylbenzenthiophenol; Preferably, the methylthiophenol is 2-methylthiophenol or 4-methylthiophenol.

6. The application according to claim 3, characterized in that, The thiophene compound containing a mercapto group is 2-mercaptothiophene or 3-mercaptothiophene.

7. A method for preparing a disulfide-based pre-vulcanizing agent for any application according to any one of claims 1 to 6, comprising the following steps: The thiol-containing organic sulfides are reacted under the catalysis of the amino acids to produce the disulfide pre-sulfurizing agent.

8. The method according to claim 7, characterized in that, The reaction is carried out in a protic solvent.

9. The method according to claim 8, characterized in that, The concentration of the mercapto-containing organic sulfide in the protic solvent is 0.1-6.25 mol / L.

10. The method according to any one of claims 7 to 9, characterized in that, The amount of the amino acid used is 10%-50% of the equivalent of the thiol-containing organosulfur compound.

11. The method according to claim 10, characterized in that, The protic solvent is selected from at least one of water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol.

12. The method according to any one of claims 7 to 11, characterized in that, The reaction is carried out at room temperature and / or for 0.5-12 hours. Preferably, the reaction is carried out in an oxygen or air atmosphere.

13. A disulfide pre-vulcanizing agent prepared by the method according to any one of claims 7 to 12.

14. The application of the disulfide presulfurizing agent prepared by any one of claims 7 to 12 or the disulfide presulfurizing agent of claim 13 in the presulfurization of hydrogenation catalysts.

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