Preparation method of tert-dodecanethiol

Abstract

The invention provides a preparation method of tert-dodecanethiol. Comprising the following steps: (a) carrying out surface coating on aluminum trichloride powder by using a polymer coating agent which can be dissolved in N-methyl pyrrolidone, and drying to obtain coated aluminum trichloride; and (b) carrying out a reaction on the coated aluminum trichloride, N-methyl pyrrolidone, dodecene and hydrogen sulfide, and then carrying out post-treatment to obtain the tert-dodecanethiol. The polymer coating agent is used for coating the surface of the aluminum trichloride, so that the dispersion state of the aluminum trichloride in the NMP can be obviously improved, and the agglomeration phenomenon is reduced. After the aluminum trichloride is uniformly dispersed, the catalyst is more uniformly distributed in a reaction system, so that side reactions, such as rearrangement, polymerization and isomerization of dodecene, caused by overhigh concentration of the local catalyst can be effectively inhibited, and the generation of byproducts such as branched-chain alkane and high-molecular olefin is reduced, thereby improving the yield and purity of tert-dodecanethiol.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic sulfur compound preparation, in particular to a preparation method of tertiary dodecanethiol. BACKGROUND

[0002] Tertiary dodecanethiol (TDDM) is an important organic sulfur compound, which is widely used in rubber, plastic and other industrial fields.

[0003] The earliest Lewis acid catalyst used for synthesizing tertiary dodecanethiol is BF3. Since BF3 is expensive, highly active, toxic, difficult to store and handle, and requires harsh reaction conditions (needs to be carried out at low temperature below 5℃, consumes a large amount of cold energy), it has gradually been replaced by AlCl3. Since solid AlCl3 is not soluble in mixed dodecene, the use of solid AlCl3 as a catalyst has poor mass transfer efficiency and low reaction activity.

[0004] The applicant found that in the existing process, aluminum chloride powder is prone to agglomeration in the solvent, leading to uneven distribution of the catalyst, excessive local catalytic concentration, and thus triggering side reactions, affecting the yield and purity of the target product. Although the industry has tried to improve by increasing stirring intensity, adding a cosolvent or replacing the catalyst, the yield improvement is limited, and often accompanied by problems such as equipment complexity or cost increase.

[0005] Therefore, how to effectively inhibit the agglomeration of aluminum chloride, improve its dispersibility, achieve uniform distribution of the catalyst, and thus improve the yield of tertiary dodecanethiol without changing the existing process framework, has become a technical problem urgently to be solved in the field. SUMMARY

[0006] In order to solve the problem of low yield of tertiary dodecanethiol caused by agglomeration of aluminum chloride, the present application provides a preparation method of tertiary dodecanethiol. The method comprises the following steps: (a) coating aluminum chloride powder with a polymer coating agent that is soluble in N-methylpyrrolidone, and drying to obtain coated aluminum chloride; (b) reacting the coated aluminum chloride, N-methylpyrrolidone, dodecene and hydrogen sulfide, and then performing post-treatment to obtain tertiary dodecanethiol.

[0007] The present application can significantly improve the dispersion state of aluminum chloride in NMP by surface coating of aluminum chloride with a polymer coating agent, reducing the agglomeration phenomenon. After uniform dispersion of aluminum chloride, the catalyst is more uniformly distributed in the reaction system, which can effectively inhibit the side reactions caused by excessive local catalyst concentration, such as rearrangement, polymerization and isomerization of dodecene, reducing the generation of by-products such as branched alkanes and high molecular weight olefins, thereby improving the yield and purity of tertiary dodecanethiol. The polymer coating agent forms a protective layer on the surface of aluminum chloride, reducing the contact between aluminum chloride and moisture in the air during storage and operation, reducing the risk of moisture absorption and hydrolysis, and improving the storage stability and operation safety of the catalyst. Unlike conventional surface modification, the high molecular coating layer of the present application coats aluminum chloride in situ, forming a swellable slow-release microcapsule in N-methylpyrrolidone. The microcapsule swells rapidly and disperses uniformly at the beginning of the reaction, eliminating local high concentration areas; then AlCl3 is released at a controlled rate, keeping the Lewis acid concentration at a level that ensures catalytic activity and inhibits side reactions. The polymer coating agent improves the dispersibility of the catalyst, reduces the formation of large particles and agglomerates, reduces the risk of equipment fouling and plugging, and helps continuous operation and maintenance of the equipment. The coating agent can be dissolved with the system after the reaction or removed together in the water washing step, reducing impurity residues and simplifying the subsequent separation and purification process.

[0008] Further, the polymer coating agent is polyethylene glycol. The hydrogen bond and van der Waals force between polyethylene glycol PEG and AlCl3 is dominant, the bond energy is low, and the controlled release can be achieved in NMP; and PEG can ensure its complete dissolution in NMP, facilitating subsequent water washing removal, avoiding impurity residues, and improving product purity.

[0009] Further, the molecular weight of the polyethylene glycol is 1000-4000. Polyethylene glycol with a molecular weight in this range can form a dense coating layer to prevent aluminum chloride agglomeration, and can dissolve quickly during the reaction to ensure uniform release of the catalyst.

[0010] Further, the amount of polyethylene glycol is 0.5-3 wt% of the mass of aluminum chloride. Within this dosage range, the coating layer thickness is moderate, which can effectively prevent aluminum chloride agglomeration and will not significantly increase the system viscosity to ensure smooth reaction.

[0011] Further, the drying is carried out at 30-60℃. This temperature range can effectively prevent the hydrolysis of aluminum chloride, while helping to form a uniform and continuous coating layer and improve the coating effect.

[0012] Further, the coated aluminum trichloride is pre-mixed with N-methyl pyrrolidone before reacting with dodecene and hydrogen sulfide. Through pre-mixing operation, the diffusion time of aluminum trichloride in the reaction system can be shortened, and the dispersion uniformity and catalytic efficiency can be further improved.

[0013] Further, the coating is formed by uniformly mixing aluminum trichloride with 0.5-3 wt% polyethylene glycol aqueous solution and then vacuum drying at 40-50°C. This process parameter helps to improve the coating efficiency, form a dense and not easy to fall off coating layer, and ensure the stability of the catalyst.

[0014] Further, the reaction is carried out at room temperature, and the hydrogen sulfide is introduced at a rate of 0.05-0.15 kg / min. The reaction at room temperature helps to reduce energy consumption, and controlling the introduction rate of hydrogen sulfide can reduce the generation of by-products and improve the yield of the target product.

[0015] Further, the post-treatment includes water washing, initial separation and recovery of unreacted dodecene, and rectification in sequence. Through step-by-step post-treatment, impurities and unreacted raw materials can be effectively removed, the purity of dodecanethiol is improved, and industrialization is facilitated.

[0016] Further, the feeding amount of the coated aluminum trichloride is 1.5-2.5 wt% of dodecene. This feeding range can ensure the catalytic activity while avoiding excessive aluminum trichloride to trigger side reactions, further improving the product yield and purity. DETAILED DESCRIPTION

[0017] In order to facilitate the understanding of the present application, the present application will be described more fully below. The present application can be implemented in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0018] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly and specifically limited. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise explicitly and specifically limited.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0020] In this application, the technical features described in an open way include both the closed technical solutions consisting of the listed features and the open technical solutions containing the listed features.

[0021] In this application, when referring to a numerical interval, unless otherwise specified, the numerical interval is considered to be continuous and includes the minimum value and the maximum value of the range, as well as every value between the minimum value and the maximum value. Further, when the range refers to integers, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0022] In this application, when referring to a percentage content, unless otherwise specified, it refers to a mass percentage for solid-liquid mixing and solid-solid mixing, and a volume percentage for liquid-liquid mixing.

[0023] In this application, when referring to a percentage concentration, unless otherwise specified, it refers to a final concentration. The final concentration refers to the proportion of the added ingredient in the system after the ingredient is added.

[0024] In this application, unless otherwise specified, the temperature parameter allows both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument.

[0025] In this application, the term "particle" or the substance with a defined particle size distribution does not necessarily have a spherical shape, but can also be irregular, and can be a primary particle or a secondary particle. The particle size of an irregular particle is calculated as the average of its maximum diameter and minimum diameter.

[0026] Example 1

[0027] This example provides a method for preparing tertiary dodecanethiol.

[0028] Preparation raw materials: 200 kg of dodecene, 4 kg of aluminum chloride, 0.04 kg of polyethylene glycol (molecular weight 4000) (1 wt% of aluminum chloride), 2 kg of deionized water, 96 kg of N-methyl pyrrolidone (NMP), and 40 kg of hydrogen sulfide.

[0029] Preparation method:

[0030] 1) Mix aluminum trichloride with 2 wt% polyethylene glycol aqueous solution uniformly, stir for 10 min;

[0031] 2) Dry under vacuum at 40°C for 2 h to obtain coated aluminum trichloride;

[0032] 3) Cool dodecene to below 10°C, send into a reaction kettle (provided with a magnetic stirrer), add NMP and coated aluminum trichloride, and stir uniformly;

[0033] 4) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 5 L / min, react for 2 h, control the reaction temperature at 10-20°C, and control the pressure at 0.1-0.2 MPa;

[0034] 5) After the reaction is completed, the reaction product is washed by a water washing tower to remove impurities;

[0035] 6) After water washing, the product is sent into a rectifying tower for rectification, and the tertiary dodecanethiol product is collected.

[0036] Example 2

[0037] The embodiment provides a preparation method of tertiary dodecanethiol.

[0038] Preparation raw materials: dodecene 200 kg, aluminum trichloride 4 kg, polyethylene glycol (molecular weight 2000) 0.08 kg (2 wt% of the mass of aluminum trichloride), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, and hydrogen sulfide 40 kg.

[0039] Preparation method:

[0040] 1) Mix aluminum trichloride with 2 wt% polyethylene glycol aqueous solution uniformly, stir for 10 min;

[0041] 2) Dry under vacuum at 40°C for 2 h to obtain coated aluminum trichloride;

[0042] 3) Cool dodecene to below 10°C, send into a reaction kettle, add NMP and coated aluminum trichloride, and stir uniformly;

[0043] 4) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 5 L / min, react for 2 h, control the reaction temperature at 10-20°C, and control the pressure at 0.1-0.2 MPa;

[0044] 5) After the reaction is completed, the reaction product is washed by a water washing tower to remove impurities;

[0045] 6) After water washing, the product is sent into a rectifying tower for rectification, and the tertiary dodecanethiol product is collected.

[0046] Example 3

[0047] This example provides a method for preparing tertiary dodecanethiol.

[0048] Preparation raw materials: dodecene 200 kg, aluminum trichloride 4 kg, polyethylene glycol (molecular weight 1000) 0.12 kg (3 wt% of the mass of aluminum trichloride), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0049] Preparation method:

[0050] 1) Mix aluminum trichloride with 3 wt% polyethylene glycol aqueous solution uniformly, stir for 10 min;

[0051] 2) Vacuum dry at 30°C for 2 h to obtain coated aluminum trichloride;

[0052] 3) Cool dodecene to below 10°C, send it into the reaction kettle, add NMP and coated aluminum trichloride, and stir uniformly;

[0053] 4) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 5 L / min, react for 2 h, control the reaction temperature at 10-20°C, and control the pressure at 0.2 MPa;

[0054] 5) After the reaction is completed, the reaction product is washed by water washing tower to remove impurities;

[0055] 6) After water washing, the product is sent into a rectifying column for rectification to collect the finished product of tertiary dodecanethiol.

[0056] Example 4

[0057] This example provides a method for preparing tertiary dodecanethiol.

[0058] Preparation raw materials: dodecene 200 kg, aluminum trichloride 4 kg, polyethylene glycol (molecular weight 4000) 0.02 kg (0.5 wt% of the mass of aluminum trichloride), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0059] Preparation method:

[0060] 1) Mix aluminum trichloride with 0.5 wt% polyethylene glycol aqueous solution uniformly, stir for 10 min;

[0061] 2) Vacuum dry at 60°C for 2 h to obtain coated aluminum trichloride;

[0062] 3) Cool dodecene to below 10°C, send it into the reaction kettle, add NMP and coated aluminum trichloride, and stir uniformly;

[0063] 4) hydrogen sulfide gas was introduced into the reactor at a flow rate of 5 L / min, and the reaction was carried out for 2 h, with the reaction temperature controlled at 20-60°C and the pressure controlled at 0.1-0.2 MPa;

[0064] 5) after the reaction, the reaction product was washed with water in a water washing tower to remove impurities;

[0065] 6) the product after water washing was sent to a rectifying tower for rectification, and the tertiary dodecanethiol product was collected.

[0066] Example 5

[0067] The present example provides a preparation method of tertiary dodecanethiol.

[0068] Preparation raw materials: 200 kg of dodecene, 4 kg of aluminum trichloride, 0.04 kg of polyethylene glycol (molecular weight 4000) (1 wt% of the mass of aluminum trichloride), 2 kg of deionized water, 96 kg of N-methyl pyrrolidone (NMP), and 40 kg of hydrogen sulfide.

[0069] Preparation method:

[0070] 1) aluminum trichloride was uniformly mixed with a 2 wt% polyethylene glycol aqueous solution, and stirred for 10 min;

[0071] 2) vacuum drying was performed at 40°C for 2 h to obtain coated aluminum trichloride;

[0072] 3) the coated aluminum trichloride was mixed with NMP, and stirred for 30 min to form a uniformly dispersed catalyst mixture;

[0073] 4) the dodecene was cooled to below 10°C, and was sent into a reactor, and the above catalyst mixture was added, with a stirring speed of 600 rpm;

[0074] 5) hydrogen sulfide gas was introduced into the reactor at a flow rate of 5 L / min, and the reaction was carried out for 2 h, with the reaction temperature controlled at 10-20°C and the pressure controlled at 0.1-0.2 MPa;

[0075] 6) after the reaction, the reaction product was washed with water in a water washing tower to remove impurities;

[0076] 7) the product after water washing was sent to a rectifying tower for rectification, and the tertiary dodecanethiol product was collected.

[0077] Example 6

[0078] The present example provides a preparation method of tertiary dodecanethiol.

[0079] Preparation raw materials: dodecene 200 kg, aluminum chloride 4 kg, polyethylene glycol (molecular weight 4000) 0.04 kg (1 wt% of the mass of aluminum chloride), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0080] Preparation method:

[0081] 1) Mix aluminum chloride with 2 wt% polyethylene glycol aqueous solution uniformly, stir for 10 min;

[0082] 2) Vacuum dry at 40°C for 2 h to obtain coated aluminum chloride;

[0083] 3) Cool dodecene to below 10°C, send it into the reaction kettle, add NMP and coated aluminum chloride, and stir uniformly;

[0084] 4) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 3 L / min, react for 3 h, control the reaction temperature at 10-20°C, and control the pressure at 0.1-0.2 MPa;

[0085] 5) After the reaction is completed, the reaction product is washed by water washing tower to remove impurities;

[0086] 6) After water washing, the product is sent into a rectifying column for rectification to collect the tertiary dodecanethiol finished product.

[0087] Example 7

[0088] The embodiment provides a preparation method of tertiary dodecanethiol.

[0089] Preparation raw materials: dodecene 200 kg, aluminum chloride 4 kg, polyethylene glycol (molecular weight 4000) 0.04 kg (1 wt% of the mass of aluminum chloride), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0090] Preparation method:

[0091] 1) Mix aluminum chloride with 2 wt% polyethylene glycol aqueous solution uniformly, stir for 10 min;

[0092] 2) Vacuum dry at 40°C for 2 h to obtain coated aluminum chloride;

[0093] 3) Cool dodecene to below 10°C, send it into the reaction kettle, add NMP and coated aluminum chloride, and stir uniformly;

[0094] 4) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 8 L / min, react for 1 h, control the reaction temperature at 10-20°C, and control the pressure at 0.1-0.2 MPa;

[0095] 5) After the reaction, the reaction product is washed by water washing tower to remove impurities;

[0096] 6) After water washing, the product is sent to a rectifying tower for rectification to collect the tertiary dodecanethiol product.

[0097] Example 8

[0098] The present example provides a preparation method of tertiary dodecanethiol.

[0099] Preparation raw materials: dodecene 200 kg, aluminum trichloride 3 kg (1.5 wt% of the mass of dodecene), polyethylene glycol (molecular weight 4000) 0.03 kg (1 wt% of the mass of aluminum trichloride), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0100] Preparation method:

[0101] 1) Mix aluminum trichloride with 2 wt% polyethylene glycol aqueous solution uniformly, and stir for 10 min;

[0102] 2) Dry at 40°C under vacuum for 2 h to obtain coated aluminum trichloride;

[0103] 3) Cool the dodecene to below 10°C, and send it to a reaction kettle, and add NMP and coated aluminum trichloride, and stir uniformly;

[0104] 4) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 5 L / min, and react for 2 h, with the reaction temperature controlled at 10-20°C and the pressure controlled at 0.1-0.2 MPa;

[0105] 5) After the reaction, the reaction product is washed by water washing tower to remove impurities;

[0106] 6) After water washing, the product is sent to a rectifying tower for rectification to collect the tertiary dodecanethiol product.

[0107] Example 9

[0108] The present example provides a preparation method of tertiary dodecanethiol.

[0109] Preparation raw materials: dodecene 200 kg, aluminum trichloride 3 kg (1.5 wt% of the mass of dodecene), polyethylene glycol (molecular weight 4000) 0.03 kg (1 wt% of the mass of aluminum trichloride), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0110] Preparation method:

[0111] 1) Mix aluminum trichloride with 2 wt% polyethylene glycol aqueous solution evenly, stir for 10 min;

[0112] 2) Dry at 40°C under vacuum for 2 h to obtain coated aluminum trichloride;

[0113] 3) Cool dodecene to below 10°C, send into a reaction kettle, add NMP and coated aluminum trichloride, and stir evenly;

[0114] 4) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 5 L / min, react for 2 h, control the reaction temperature at 10-20°C, and control the pressure at 0.1-0.2 MPa;

[0115] 5) After the reaction is completed, the reaction product is washed by a water washing tower to remove impurities;

[0116] 6) After water washing, the product is sent into a rectifying column for rectification to collect the product of tert-dodecyl mercaptan.

[0117] Example 10

[0118] The present example provides a preparation method of tert-dodecyl mercaptan.

[0119] Preparation raw materials: dodecene 200 kg, aluminum trichloride 4 kg, polyethylene glycol (molecular weight 4000) 0.04 kg (1 wt% of the mass of aluminum trichloride), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, and hydrogen sulfide 40 kg.

[0120] Preparation method:

[0121] 1) Mix aluminum trichloride with 2 wt% polyethylene glycol aqueous solution evenly, stir for 10 min;

[0122] 2) Dry at 40°C under vacuum for 2 h to obtain coated aluminum trichloride;

[0123] 3) Cool dodecene to below 10°C, send into a reaction kettle, add NMP and coated aluminum trichloride, and stir evenly;

[0124] 4) Use a circulating mixing kettle and a pressure pump to circulate the reaction product back to the reaction kettle for 2 times, each time for 30 min, to improve the mixing uniformity;

[0125] 5) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 5 L / min, react for 2 h, control the reaction temperature at 10-20°C, and control the pressure at 0.1-0.2 MPa;

[0126] 6) After the reaction is completed, the reaction product is washed by a water washing tower to remove impurities;

[0127] 7) The product after water washing is sent to a rectification tower for rectification, and the tertiary dodecyl mercaptan finished product is collected.

[0128] Comparative Example 1

[0129] The present comparative example provides a preparation method of uncoated aluminum trichloride tertiary dodecyl mercaptan.

[0130] Preparation raw materials: dodecene 200 kg, aluminum trichloride 4 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0131] Preparation method:

[0132] 1) The dodecene is cooled to below 10°C, and is sent to a reaction kettle, and NMP and aluminum trichloride powder are added and stirred uniformly;

[0133] 2) Hydrogen sulfide gas is introduced into the reaction kettle at a flow rate of 5 L / min, and the reaction is carried out for 2 h, with the reaction temperature controlled at 10-20°C and the pressure controlled at 0.1-0.2 MPa;

[0134] 3) After the reaction is completed, the reaction product is water washed by a water washing tower to remove impurities;

[0135] 4) The product after water washing is sent to a rectification tower for rectification, and the tertiary dodecyl mercaptan finished product is collected.

[0136] Comparative Example 2

[0137] The present comparative example provides a preparation method of aluminum trichloride mixed with deionized water and then dried directly.

[0138] Preparation raw materials: dodecene 200 kg, aluminum trichloride 4 kg, deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0139] Preparation method:

[0140] 1) The aluminum trichloride is mixed with deionized water and stirred for 10 min;

[0141] 2) Vacuum drying at 40°C for 2 h to obtain dried aluminum trichloride;

[0142] 3) The dodecene is cooled to below 10°C, and is sent to a reaction kettle, and NMP and dried aluminum trichloride are added and stirred uniformly;

[0143] 4) Hydrogen sulfide gas is introduced into the reaction kettle at a flow rate of 5 L / min, and the reaction is carried out for 2 h, with the reaction temperature controlled at 10-20°C and the pressure controlled at 0.1-0.2 MPa;

[0144] 5) After the reaction is completed, the reaction product is water washed by a water washing tower to remove impurities;

[0145] 6) The product after water washing is sent to a rectifying column for rectification, and the tertiary dodecanethiol finished product is collected.

[0146] Comparative Example 3

[0147] This comparative example provides a preparation method of tertiary dodecanethiol.

[0148] Preparation raw materials: dodecene 200 kg, aluminum trichloride 4 kg, 3- aminopropyltriethoxysilane (KH-550) 0.104 kg (1 wt% of AlCl3), deionized water 2 kg, N-methyl pyrrolidone (NMP) 96 kg, hydrogen sulfide 40 kg.

[0149] Preparation method:

[0150] 1) Dissolve KH-550 in anhydrous ethanol, add AlCl3 powder, and stir at 25°C for 30 min for silanization coating;

[0151] 2) Dry under vacuum at 60°C for 2 h to obtain silane-coated aluminum trichloride;

[0152] 3) Cool the dodecene to below 10°C, and send it to a reaction kettle (equipped with a magnetic stirrer), add NMP and silane-coated aluminum trichloride, and stir uniformly;

[0153] 4) Introduce hydrogen sulfide gas into the reaction kettle at a flow rate of 5 L / min, react for 2 h, control the reaction temperature at 10-20°C, and control the pressure at 0.1-0.2 MPa;

[0154] 5) After the reaction is completed, the reaction product is water washed by a water washing tower to remove impurities;

[0155] 6) The product after water washing is sent to a rectifying column for rectification, and the tertiary dodecanethiol finished product is collected.

[0156] Performance test method

[0157] The yield of tertiary dodecanethiol is calculated by the ratio of product weight to theoretical yield, and the purity is determined by gas chromatography.

[0158] Table 1 Test results of examples and comparative examples.

[0159] No. Yield (%) Purity (%) Example 1 91.2 98.5 Example 2 90.8 98.3 Example 3 90.5 98.1 Example 4 90.7 98.2 Example 5 91.4 98.6 Example 6 90.6 98.2 Example 7 90.8 98.3 Example 8 90.4 98.0 Example 9 91.1 98.4 Example 10 91.5 98.7 Comparative Example 1 88.9 95.5 Comparative Example 2 89.1 95.7 Comparative Example 3 89.4 96.1

[0160] As can be seen from Table 1, the yield and purity of all examples are higher than those of the comparative examples, while the yield of Comparative Example 1 (uncoated aluminum trichloride) is only 88.9% and the purity is 95.5%, because the surface coating of aluminum trichloride by the polymer coating agent can significantly improve the dispersion state of aluminum trichloride in NMP and reduce the agglomeration phenomenon. After uniform dispersion of aluminum trichloride, the catalyst is more uniformly distributed in the reaction system, which can effectively inhibit the side reactions caused by excessive local catalyst concentration, such as rearrangement, polymerization and isomerization of dodecene, reduce the generation of by-products such as branched alkanes and high molecular alkenes, and thus improve the yield and purity of tertiary dodecyl mercaptan. The polymer coating agent forms a protective layer on the surface of aluminum trichloride, reducing the contact of aluminum trichloride with moisture in the air during storage and operation, reducing the risk of moisture absorption and hydrolysis, and improving the storage stability and operation safety of the catalyst. Unlike conventional surface modification, the high molecular coating layer of the present application coats aluminum trichloride in situ, forming a swellable slow-release microcapsule in N-methylpyrrolidone. The microcapsule swells rapidly and disperses uniformly at the beginning of the reaction, eliminating local high concentration areas; then AlCl3 is released at a controlled rate, so that the Lewis acid concentration is always maintained at a level that ensures catalytic activity and inhibits side reactions. Comparative Example 1 is not coated, resulting in severe agglomeration of AlCl3 and low catalytic efficiency. Comparative Example 2 is only dried with water, and the coating layer is not dense, so the dispersibility is limited. Although the silane coating of Comparative Example 3 can inhibit agglomeration to some extent, the hydrophobic cross-linked layer is difficult to swell in NMP, resulting in too rapid release of AlCl3, excessive local catalyst concentration, and still obvious side reactions.

[0161] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

[0162] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A method for preparing tert-dodecyl mercaptan, characterized in that: The following steps are involved: (a) coating aluminum trichloride powder with a polymer coating agent soluble in N-methylpyrrolidone, and drying to obtain coated aluminum trichloride; (b) reacting the coated aluminum trichloride, N-methylpyrrolidone, dodecene, and hydrogen sulfide, followed by post-treatment to obtain tert-dodecyl mercaptan.

2. The preparation method according to claim 1, characterized in that The polymer coating agent is polyethylene glycol.

3. The preparation method according to claim 2, characterized in that The molecular weight of the polyethylene glycol is 1000-4000.

4. The preparation method according to claim 2, characterized in that The amount of polyethylene glycol used is 0.5-3 wt% of the mass of aluminum chloride.

5. The preparation method according to claim 2, characterized in that The coating is carried out by uniformly mixing aluminum trichloride with a 0.5-3 wt % polyethylene glycol aqueous solution, and then vacuum drying at 40-50° C.

6. The preparation method according to claim 1, characterized in that The coated aluminum trichloride is premixed with N-methylpyrrolidone and then reacted with dodecene and hydrogen sulfide.

7. The preparation method according to claim 1, characterized in that The drying is carried out at 30-60°C.

8. The preparation method according to claim 1, characterized in that The reaction is carried out at room temperature, and the rate of introduction of hydrogen sulfide is 0.05-0.15 kg / min.

9. The preparation method according to claim 1, characterized in that The post-treatment includes water washing, recovery of unreacted dodecene in a primary fractionation tower and distillation in sequence.

10. The preparation method according to claim 1, characterized in that The feeding amount of the coated aluminum trichloride is 1.5-2.5 wt% of dodecene.