A method for synthesizing long straight-chain alkyltoluenes

Abstract

This invention relates to the field of organic synthesis technology, and more particularly to a method for synthesizing long-chain alkyltoluenes. Targeting the structural characteristics of C20-C24 long-chain α-olefins, this invention uses granular anhydrous aluminum trichloride instead of the traditional powdered anhydrous aluminum trichloride and hydrogen chloride composite catalytic system. The smaller specific surface area of ​​granular anhydrous aluminum trichloride results in a controllable reaction rate, slower deactivation, and longer activity retention compared to powdered aluminum trichloride. Through the design of a slow reaction system, the synthesis of long-chain alkyltoluenes can be achieved through a single feed, simplifying the process. It is suitable for raw materials with high water content (maintaining high catalytic activity even when the water content of toluene and long-chain α-olefins is ≤0.5% by mass), eliminating the need for drying treatment, saving investment in drying equipment and energy consumption, and also offering the advantage of a short reaction cycle.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a method for synthesizing long-chain alkyltoluene. Background Technology

[0002] C20-C24 long-chain alkyltoluenes have a wide range of industrial applications, such as in the production of high-temperature lubricants, high-end surfactants, and polymer compatibilizers.

[0003] The existing technology for synthesizing C20-C24 long straight-chain alkyl toluenes generally adopts the following two methods: The first method involves preparing a catalyst (using anhydrous aluminum trichloride, hydrogen chloride, and toluene as raw materials), adding the catalyst dropwise during the reaction, and simultaneously adding a mixed liquid of toluene and α-olefins, while also introducing hydrogen chloride; The second method involves directly adding anhydrous aluminum trichloride during the reaction, while simultaneously adding a mixed liquid of toluene and α-olefins, and simultaneously introducing hydrogen chloride.

[0004] Existing processes have stringent requirements for the moisture content of raw materials (typically ≤50ppm), necessitating additional drying steps such as distillation and adsorption, which increases equipment investment and energy consumption, and extends the production cycle. Furthermore, batch-feeding of raw materials (such as α-olefins) is complex and has a long reaction cycle. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for synthesizing long-chain alkyltoluenes. The synthesis method provided by this invention involves a single-feed process, is simple, is suitable for raw materials with high water content, requires no drying treatment, and has the advantages of short reaction cycle and significant economic benefits.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for synthesizing long-chain alkyltoluene, comprising the following steps:

[0008] Instead of drying toluene and long-chain α-olefins, toluene, long-chain α-olefins, and anhydrous aluminum trichloride are directly mixed in one step, and then alkylation is carried out by passing hydrogen chloride to obtain the long-chain alkyl toluene.

[0009] The water content in the long straight-chain α-olefin is ≤0.5% by mass; the structural formula of the long straight-chain α-olefin is R-CH2=CH2, where R is a C20-C24 straight-chain alkyl group;

[0010] The toluene contains ≤0.5% water by mass.

[0011] The anhydrous aluminum trichloride is in granular form, and its specific surface area is 0.000409~0.000603 m². 2 / g.

[0012] Preferably, the anhydrous aluminum trichloride has an average particle size of 4-6 mm.

[0013] Preferably, the molar ratio of toluene to long straight-chain α-olefin is ≥5:1.

[0014] Preferably, the mass of the anhydrous aluminum trichloride is more than 0.36% of the total mass of toluene and long straight-chain α-olefins.

[0015] Preferably, the alkylation reaction is carried out at a temperature of 20-50°C.

[0016] Preferably, the hydrogen chloride introduction rate satisfies the pressure of the reaction system being 0~30 Pa.

[0017] Preferably, before the alkylation reaction is carried out with hydrogen chloride, the air in the reaction system is replaced with nitrogen.

[0018] Preferably, the alkylation reaction is carried out under stirring conditions.

[0019] Preferably, after the alkylation reaction is completed, the process further includes adding bentonite to the system after the reaction for purification, followed by solid-liquid separation, and heating the resulting liquid to remove toluene and water.

[0020] Preferably, the hydrogen chloride has a purity of ≥99.9% and a water content of ≤10ppm.

[0021] This invention provides a method for synthesizing long-chain alkyltoluene, comprising the following steps: without drying toluene and the long-chain α-olefin, directly mixing toluene, the long-chain α-olefin, and anhydrous aluminum trichloride in a single step, followed by alkylation reaction with hydrogen chloride to obtain the long-chain alkyltoluene; the water content in the long-chain α-olefin is ≤0.5% by mass; the structural formula of the long-chain α-olefin is R-CH2=CH2, where R is a C20-C24 straight-chain alkyl group; the water content in the toluene is ≤0.5% by mass; the anhydrous aluminum trichloride is in granular form, and the specific surface area of ​​the anhydrous aluminum trichloride is 0.000409~0.000603 m². 2 / g.

[0022] This invention targets the structural characteristics of C20-C24 long straight-chain α-olefins, selecting granular anhydrous aluminum trichloride instead of the traditional powdered anhydrous aluminum trichloride and hydrogen chloride as a composite catalytic system. The smaller specific surface area of ​​granular anhydrous aluminum trichloride leads to controllable reaction rate, slower deactivation and longer activity retention compared to powdered aluminum trichloride. Through the design of a slow reaction system, the synthesis of long straight-chain alkyl toluenes can be achieved through a single feed, simplifying the process. It is suitable for raw materials with high water content (maintaining high catalytic activity even when the water content of the raw material is ≤0.5% (toluene) or ≤0.5% (long straight-chain α-olefins)). No drying treatment is required, saving investment in drying equipment and energy consumption, while also having the advantage of a short reaction cycle.

[0023] All related technologies use powdered anhydrous aluminum trichloride (specific surface area 2.5~3.5m²). 2 Powdered anhydrous aluminum trichloride catalysts have a large specific surface area, which leads to rapid contact with long-chain raw materials. This can cause carbon buildup or coordination poisoning due to violent local reactions, resulting in rapid deactivation, low catalyst utilization, and short activity retention time. This invention uses granular anhydrous aluminum trichloride catalysts, which provide a milder reaction process and a longer activity retention time. Detailed Implementation

[0024] This invention provides a method for synthesizing long-chain alkyltoluene, comprising the following steps:

[0025] Instead of drying the toluene and the long-chain α-olefin, the toluene, the long-chain α-olefin, and anhydrous aluminum trichloride are directly mixed in one step, and then hydrogen chloride is passed through to carry out an alkylation reaction to obtain the long-chain alkyl toluene.

[0026] In this invention, the purity of the toluene is preferably ≥99%; the toluene is preferably industrial toluene; the water content in the toluene is preferably ≤0.5% by mass, and in specific embodiments it can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

[0027] In this invention, the long straight-chain α-olefin has the structural formula R-CH2=CH2, where R is a C20-C24 straight-chain alkyl group. In specific embodiments, the long straight-chain α-olefin can be one or a mixture of several C20, C21, C22, C23, and C24 long straight-chain α-olefins. In this invention, the water content in the long straight-chain α-olefin is preferably ≤0.5% by mass, and in specific embodiments it can be 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%.

[0028] In this invention, the preferred molar ratio of toluene to long-chain α-olefin is 5:1. By controlling the molar ratio of toluene to long-chain α-olefin, with toluene in excess relative to the long-chain α-olefin, this invention can, on the one hand, inhibit the self-polymerization reaction of the long-chain α-olefin, and on the other hand, dilute the trace amounts of moisture in the raw materials, reducing their impact on catalytic activity.

[0029] In this invention, the anhydrous aluminum trichloride is in granular form, and the average particle size of the anhydrous aluminum trichloride is preferably 4-6 mm, but in specific embodiments it can be 5.5 mm or 5 mm; the specific surface area of ​​the anhydrous aluminum trichloride is 0.000409-0.000603 m². 2 / g, which in a specific embodiment can be 0.000491m 2 / g. This invention uses granular anhydrous aluminum trichloride, which has a small specific surface area, slow reaction rate, reduced carbon formation on the catalyst surface, and lower deactivation rate, while also reducing sensitivity to moisture content in the raw materials. This invention controls the average particle size of the anhydrous aluminum trichloride to 5mm, balancing reaction efficiency, catalyst lifetime, and tolerance to moisture content in the raw materials. In this invention, the mass of the anhydrous aluminum trichloride is preferably 0.36% or more of the total mass of toluene and long-chain α-olefins, more preferably 0.36%. 0.36% is the minimum amount required for producing qualified products using conventional catalyst methods; this invention achieves high-quality long-chain alkyl toluenes with minimal catalyst usage.

[0030] In this invention, the purity of the hydrogen chloride is preferably ≥99.9%, and the water content is preferably ≤10ppm. The hydrogen chloride introduction rate in this invention can be determined according to relevant technologies, i.e., maintaining a slight positive pressure (0~30Pa) in the reaction vessel. Controlling this slight positive pressure in this invention helps maintain the catalytic activity of aluminum trichloride (forming an AlCl3·HCl complex) and enhances the catalytic system's tolerance to moisture in the raw materials.

[0031] Before the alkylation reaction by introducing hydrogen chloride, the air in the reaction system is preferably replaced with nitrogen. In this invention, the nitrogen introduction time is preferably 3-5 minutes. This invention does not have special requirements for the nitrogen introduction rate; a rate well-known in the art can be used, which is 0.5 L / min in a specific embodiment.

[0032] In this invention, the preferred temperature for the alkylation reaction is 20-50°C, more preferably 25-50°C. In embodiments of this invention, the temperature of the alkylation reaction fluctuates; that is, the temperature automatically rises after the introduction of hydrogen chloride due to exothermic reaction. This invention utilizes a heating and cooling device to maintain the temperature of the alkylation reaction within the aforementioned range. In this invention, when the temperature is below 20°C, the reaction rate of the long-chain feedstock is too low; when the temperature is above 50°C, catalyst deactivation accelerates and the influence of trace amounts of moisture in the feedstock intensifies.

[0033] In this invention, the alkylation reaction is carried out until the reaction is no longer exothermic.

[0034] In this invention, the equation for the alkylation reaction is as follows:

[0035] .

[0036] In this invention, the alkylation reaction is preferably carried out under stirring conditions. This invention does not have special requirements for the stirring rate, and a stirring rate well known in the art can be used. In the embodiments of this invention, it is 200 r / min.

[0037] After the alkylation reaction is completed, the present invention preferably further includes adding bentonite to the reaction system for purification, followed by solid-liquid separation, and heating the resulting liquid to remove toluene and water to obtain the long-chain alkyltoluene.

[0038] This invention utilizes granular anhydrous aluminum trichloride and a simplified one-time feeding process, which can be adapted to high-moisture raw material systems, eliminating the drying step, shortening the reaction cycle, and achieving high selectivity, high stability, low energy consumption, and low cost industrial production.

[0039] The following detailed description, in conjunction with embodiments, illustrates the method for synthesizing alkyltoluenes from toluene and α-olefins in a particulate aluminum trichloride-hydrogen chloride system using a single feeding method provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0040] The α-olefins used in the following examples and comparative examples are long-chain C20 olefins; the anhydrous aluminum trichloride powder used has an average particle size of 1 μm and a specific surface area of ​​2.5~3.5 m². 2 / g; The average particle size of the granular anhydrous aluminum trichloride used was 5mm, and the specific surface area was 0.000491m². 2 / g.

[0041] Example 1

[0042] One-time input: 345.53g toluene (5000ppm water), 210.40g α-olefin (5000ppm water), and 2g anhydrous aluminum trichloride (granular).

[0043] Add 345.53 g of toluene, 210.40 g of α-olefin, and 2 g of anhydrous granular aluminum trichloride at room temperature. Start stirring at a stirring rate of 200 r / min and displace with nitrogen (0.5 L / min) for 3 min; Charge hydrogen chloride at 30 mL / min. When charging hydrogen chloride, maintain a slightly positive pressure in the reaction vessel. At the beginning, the speed is relatively fast at 30 mL / min, and then it slows down when the absorption is not good. As hydrogen chloride is charged, the temperature of the material rises. Control the reaction temperature at 45 - 50 °C. After reacting for about 10 min, the temperature can reach 45 - 50 °C. React for 30 min, and when the heat release of the material ends, stop charging hydrogen chloride. The bromine value of the material is tested to be 0.01.

[0044] Add 40 g of bentonite and stir for 1 min, then filter. After filtration, the material is heated at 140 °C to remove toluene to obtain the finished product. Bromine value: 0.01, chromaticity: 0.2, V40: 17.10 mm 2 / s, and the product is qualified.

[0045] Note: The lower the bromine value, the higher the conversion rate. When the bromine value ≤ 0.05, it is qualified; specifically, the bromine value is measured according to GB / T 1815-2019. The bromine value is the core index to measure the content of unsaturated hydrocarbons in organic substances and is defined as the number of grams of bromine consumed by reacting 100 g of the sample with bromine单质; Chromaticity: color number (diluted), measured according to GB / T6540; Kinematic viscosity (40 °C) is measured according to GB / T 265.

[0046] Example 2 (the only difference from Example 1 is that the moisture content of the raw materials is lower)

[0047] Charge all at once. Raw material situation: Charge 345.53 g of toluene with water content ≤ 5 ppm; 210.40 g of α-olefin with water content ≤ 5 ppm; 2 g of anhydrous aluminum trichloride, granular.

[0048] Add 345.53 g of toluene, 210.40 g of α-olefin, and 2 g of anhydrous granular aluminum trichloride at room temperature. Start stirring at a stirring rate of 200 r / min and displace with nitrogen (0.5 L / min) for 3 min; Charge hydrogen chloride at 30 mL / min. When charging hydrogen chloride, maintain a slightly positive pressure in the reaction vessel. As hydrogen chloride is charged, the temperature of the material rises. Control the reaction temperature at 45 - 50 °C. After reacting for about 10 min, the temperature can reach 45 - 50 °C. React for 30 min, and when the heat release of the material ends, the feeding rate of hydrogen chloride ≥ 0.1 mL / min, then stop charging hydrogen chloride. The bromine value of the material is tested to be 0.01.

[0049] Add 40 g of bentonite and stir for 1 min, then filter. After filtration, the material is heated at 140 °C to remove toluene to obtain the finished product. Bromine value: 0.01, chromaticity: 0.2, V40: 17.93 mm 2 / s, and the product is qualified.

[0050] Example 3

[0051] One-time input: 345.53g toluene (4810ppm water), 210.40g α-olefin (4920ppm water), and 2g anhydrous aluminum trichloride (granular).

[0052] Add 345.53g of toluene, 210.40g of α-olefin, and 2g of anhydrous granular aluminum trichloride at room temperature. Start stirring at 200 rpm and purge with nitrogen (0.5L / min) for 3 minutes. Add hydrogen chloride at 30mL / min, maintaining a slight positive pressure in the reaction vessel initially at a faster rate of 30mL / min, slowing down as absorption decreases. As hydrogen chloride is added, the material temperature rises. Control the reaction temperature at 45-50℃. The temperature reaches 45-50℃ within approximately 10 minutes. After 30 minutes, the exothermic reaction ends, and the hydrogen chloride injection is stopped. The Br valence of the material is 0.02.

[0053] Add 40g of bentonite and stir for 1 minute, then filter. After filtration, remove toluene from the filtered material at 140℃ to obtain the final product. Br valence: 0.02, color: 0.2, V40: 18.30mm. 2 / s, the product is qualified.

[0054] Example 4

[0055] One-time input: 345.53g toluene (4900ppm water), 210.40g α-olefin (4100ppm water), and 2g anhydrous aluminum trichloride (granular).

[0056] Add 345.53g of toluene, 210.40g of α-olefin, and 2g of anhydrous granular aluminum trichloride at room temperature. Start stirring at 200 rpm and purge with nitrogen (0.5L / min) for 3 minutes. Add hydrogen chloride at 30mL / min, maintaining a slight positive pressure in the reaction vessel initially at a faster rate of 30mL / min, slowing down as absorption decreases. As hydrogen chloride is added, the material temperature rises. Control the reaction temperature at 45-50℃. The temperature reaches 45-50℃ within approximately 10 minutes. Continue the reaction for 30 minutes until the exothermic reaction ends, then stop adding hydrogen chloride. The Br valence of the material is 0.01.

[0057] Add 40g of bentonite and stir for 1 minute, then filter. After filtration, remove toluene from the filtered material at 140℃ to obtain the final product. Br valence: 0.01, color: 0.2, V40: 18.90mm. 2 / s, the product is qualified.

[0058] Comparative Example 1 (Catalyst Addition Method)

[0059] Catalyst preparation: Add 16.67g of powdered anhydrous aluminum trichloride and 46.07g of toluene to a dry three-necked flask, stir and heat to 40℃, and slowly introduce hydrogen chloride gas at a rate of 20~40mL / min. This reaction is exothermic, so control the reaction temperature at 50℃ and the reaction time at 100min. The exothermic reaction decreases in the later stage and finally stops. The reaction is then complete. Place the prepared catalyst in a glass bottle for later use.

[0060] Raw material information: Both toluene and α-olefins used contain ≤50ppm water. The base material consisted of 138.21g (1.5mol) of toluene; 201.80g (2.19mol) of toluene and 210.40g (0.75mol) of α-olefins were mixed thoroughly in the same beaker and set aside for later use; 8.07g of catalyst (containing H...) + [AlCl4] - 2.55g, 5.52g of toluene (0.60mol of toluene) totaled 3.75mol of toluene (345.53g).

[0061] Add 138.21g of toluene as a base material to a dry four-necked flask at room temperature. Attach a two-way bifurcated tube to the left neck; one port is connected to a thermometer, and the other port is shared by nitrogen and hydrogen chloride. Install a stirrer in the middle neck and an atmospheric pressure funnel at the front neck for adding the toluene-α-olefin mixture dropwise. Attach a two-way bifurcated tube to the right neck; one port is connected to a catalyst dropper, and the other to a condenser. Above the condenser is a bubbler (containing a small amount of neutral oil), connected by a tubing to an alkaline solution bottle (containing 2000mL of 20% sodium hydroxide solution) to absorb excess hydrogen chloride.

[0062] Add toluene as the base material and start stirring at a rate of 200 rpm. Purge with nitrogen for 3 minutes at a rate of 0.5 L / min. Heat to 40°C and add 412.20 g of a toluene and α-olefin mixture dropwise at a rate of 10.31 g / min, completing the addition in 40 minutes. Simultaneously add 8.07 g of catalyst (pre-added to the dropping tube and attached to the right-side fork tube) at a rate of 0.202 g / min, completing the addition in 40 minutes. While adding the materials and catalyst, purge hydrogen chloride gas into the four-necked flask, maintaining a slight positive pressure (i.e., weak bubbling from the bubbler). During the addition of the catalyst, toluene, and α-olefin, gradually raise the temperature in the four-necked flask to 50°C (approximately 10 minutes) and maintain this temperature. Stop the hydrogen chloride purging after the addition is complete. Test a small amount of the material for bromine value; the result shows a bromine value of 0.07. Maintain the temperature at 50℃ for 1 hour, take a small amount of material to test the bromine value. If the bromine value is 0.05, the product is qualified (the product is qualified if the bromine value of alkyltoluene is ≤0.05).

[0063] Add 40g of bentonite for filtration to the product, stir for 1 minute, and then filter. After filtering, remove toluene from the material at 140℃ to obtain the finished product.

[0064] After testing, the bromine value was 0.05, the color was 0.4, and the kinematic viscosity (V40) at 40°C was 19.91 mm. 2 / s, the product is qualified.

[0065] Comparative Example 2 (Catalyst Addition Method)

[0066] The difference between this comparative example and Comparative Example 1 is that the toluene and α-olefin used are highly hydrated, with a water content of 4000~5000ppm.

[0067] The reaction process was the same as in Comparative Example 1. After the addition of hydrogen chloride was completed and stopped, the Br valence of the material was measured to be 0.16. After maintaining the temperature for 1 hour, the Br valence was measured to be 0.1, which was unqualified. The product obtained after filtration and distillation showed the following test results: Br valence: 0.1, color: 0.35, V40: 20.31 mm. 2 / s, the product is defective.

[0068] The results of Comparative Examples 1 and 2 show that the traditional catalytic method (preparing the catalyst first, adding the catalyst dropwise during the reaction, and simultaneously adding a mixture of toluene and α-olefin) has high requirements for the water content of toluene and α-olefin.

[0069] Comparative Example 3 (Anhydrous aluminum trichloride was added directly, followed by the addition of a mixture of toluene and α-olefin; the anhydrous aluminum trichloride was in powder form, and the toluene and α-olefin contained ≤50 ppm of water).

[0070] 138.21 g (1.5 mol) of toluene, 207.32 g (2.25 mol) of toluene and 210.40 g (0.75 mol) of α-olefin were placed in the same beaker and mixed thoroughly for later use. The total amount of the mixture was 417.72 g.

[0071] Add 138.21g of toluene and 2g of anhydrous aluminum trichloride (powder) to the substrate at room temperature. Start stirring at 200 rpm and purge with nitrogen (0.5 L / min) for 3 minutes. Raise the temperature to 40°C and add 417.72g of a toluene-α-olefin mixture dropwise at a rate of 10.45g / min, completing the addition in 40 minutes. Simultaneously, introduce hydrogen chloride gas into the four-necked flask, maintaining a slight positive pressure (i.e., weak bubbling from the bubbler). The addition of material and the introduction of hydrogen chloride are exothermic processes; the material temperature rises to approximately 50°C in about 10 minutes and is maintained at 50°C. Stop introducing hydrogen chloride after the addition is complete. Test the material for Br: 0.06; maintain the temperature at 50°C for 1 hour, and test for Br: 0.05, which is acceptable.

[0072] The material was filtered after adding 40g of bentonite, and the temperature was raised to 140℃ to remove toluene, yielding the product with: Br valence: 0.05, color: 0.2, V40: 22.21mm. 2 / s, the product is qualified.

[0073] Comparative Example 4 (Anhydrous aluminum trichloride was added directly, followed by the addition of a mixture of toluene and α-olefin; the anhydrous aluminum trichloride was in powder form, and the toluene and α-olefin contained 4000~5000 ppm of water).

[0074] The reaction process was the same as in Comparative Example 3. After the addition was complete, the Br valence was 0.17; after 1 hour at a constant temperature, the Br valence was 0.12.

[0075] The product was obtained by filtration and distillation. Br valence: 0.12, color: 0.3, V40: 23.12mm. 2 / s, the product is defective.

[0076] The results of Comparative Examples 3 and 4 indicate that the traditional method of adding powdered aluminum trichloride in one step and then adding a mixture of toluene and α-olefins requires high moisture content in the materials. If the moisture content of the materials is high, the reaction product will be substandard.

[0077] Comparative Example 5 (Anhydrous aluminum trichloride was added directly, followed by the addition of a mixture of toluene and α-olefin; the anhydrous aluminum trichloride was in granular form, and the toluene and α-olefin contained ≤50 ppm of water).

[0078] The reaction process was the same as in Comparative Example 3. After the addition was complete, the Br valence was 0.08; after 1 hour at a constant temperature, the Br valence was 0.04.

[0079] The final product was obtained by filtration and distillation. Br valence: 0.04, color: 0.2, V40: 21.51 mm. 2 / s, the product is qualified.

[0080] Comparative Example 6 (Anhydrous aluminum trichloride was added directly, followed by the addition of a mixture of toluene and α-olefin; the anhydrous aluminum trichloride was in granular form, and the toluene and α-olefin contained 4000~5000 ppm of water).

[0081] The reaction process was the same as in Comparative Example 3. After the addition was complete, the Br valence was 0.15. After 1 hour at a constant temperature, the Br valence was 0.10.

[0082] The final product was obtained by filtration and distillation. Br valence: 0.1, color: 0.3, V40: 22.30 mm. 2 / s, the product is defective.

[0083] The results of Comparative Examples 5 and 6 indicate that the method of adding granular aluminum trichloride in one go, combined with the dropwise addition of a mixture of toluene and α-olefins, results in substandard products regardless of whether the material has a high or low moisture content.

[0084] Comparative Example 7 (One-time Investment)

[0085] Raw material details: 345.53g toluene, water content ≤50ppm; 210.40g α-olefin, water content ≤50ppm; 2g anhydrous aluminum trichloride, powder.

[0086] Add 345.53g of toluene, 210.40g of α-olefin, and 2g of anhydrous powdered aluminum trichloride at room temperature. Start stirring at 200 rpm and purge with nitrogen (0.5 L / min) for 3 min. Add hydrogen chloride at 30 mL / min, maintaining a slight positive pressure in the reaction vessel. As hydrogen chloride is added, the material temperature rises; control the reaction temperature at 45-50℃. The temperature reaches 45-50℃ after approximately 10 min of reaction. After 30 min, the exothermic reaction ends, and the hydrogen chloride flow rate is ≥0.1 mL / min. Stop adding hydrogen chloride. The Br valence of the material is 0.03.

[0087] Add 40g of bentonite and stir for 1 minute, then filter. After filtration, remove toluene from the filtered material at 140℃ to obtain the final product. Br valence: 0.03, color: 0.2, V40: 18.32mm. 2 / s, the product is qualified.

[0088] Comparative Example 8 (One-time Investment)

[0089] Raw material details: 345.53g of toluene with a water content of 4000~5000ppm; 210.40g of α-olefin with a water content of 4000~5000ppm; and 2g of anhydrous aluminum trichloride in powder form.

[0090] The reaction was the same as in Comparative Example 7. After 30 minutes of reaction, the Br valence was 0.12. After adding 40g of bentonite and filtering, and removing toluene at 140℃, the Br valence of the material was 0.12, the color was 0.2, and the V40 was 21.41 mm. 2 / s, the product is defective.

[0091] The results of Comparative Examples 7 and 8 show that, when using the one-time addition method, if the aluminum trichloride used is in powder form, products with high water content in toluene and α-olefins are unqualified, while products with low water content are qualified.

[0092] As can be seen from the results of the above examples and comparative examples, the method of adding granular aluminum trichloride in one go saves reaction time by eliminating the one-hour constant temperature time required in the previous reaction, resulting in better reaction effect and eliminating the need for dehydration of the reaction raw materials.

[0093] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing long-chain straight-chain alkyltoluene, characterized in that, Includes the following steps: Instead of drying toluene and long-chain α-olefins, toluene, long-chain α-olefins, and anhydrous aluminum trichloride are directly mixed in one step, and then alkylation is carried out by passing hydrogen chloride to obtain the long-chain alkyl toluene. The water content in the long straight-chain α-olefin is ≤0.5% by mass; the structural formula of the long straight-chain α-olefin is R-CH2=CH2, where R is a C20-C24 straight-chain alkyl group; The toluene contains ≤0.5% water by mass. The anhydrous aluminum trichloride is in granular form, and its specific surface area is 0.000409~0.000603 m². 2 / g.

2. The synthesis method according to claim 1, characterized in that, The anhydrous aluminum trichloride has an average particle size of 4-6 mm.

3. The synthesis method according to claim 1, characterized in that, The molar ratio of toluene to long-chain α-olefin is ≥5:

1.

4. The synthesis method according to claim 1 or 3, characterized in that, The mass of the anhydrous aluminum trichloride is more than 0.36% of the total mass of toluene and long straight-chain α-olefins.

5. The synthesis method according to claim 1, characterized in that, The alkylation reaction is carried out at a temperature of 20~50℃.

6. The synthesis method according to claim 1, characterized in that, Before the alkylation reaction is carried out by passing hydrogen chloride, the air in the reaction system is replaced with nitrogen.

7. The synthesis method according to claim 1, characterized in that, The alkylation reaction was carried out under stirring conditions.

8. The synthesis method according to claim 1, characterized in that, After the alkylation reaction is completed, the process also includes adding bentonite to the system after the reaction for purification, followed by solid-liquid separation, and heating the resulting liquid to remove toluene and water.

9. The synthesis method according to claim 1, characterized in that, The hydrogen chloride has a purity of ≥99.9% and a water content of ≤10ppm.