Preparation method of tert-butyl lithium

Abstract

The invention relates to the technical field of tert-butyllithium preparation, in particular to a tert-butyllithium preparation method which comprises the following steps: preparing raw materials, dissolving lithium and washing oil, mixing the raw materials to start reaction, dropwise adding a modifier, carrying out heat preservation treatment, cooling, settling and taking clear liquid. According to the method, trace impurities on the surface of lithium are removed in the pretreatment link, the PVP coating can block contact of water, oxygen and lithium in a long-acting mode, lithium is prevented from going bad in the earlier stage of storage and reaction, and meanwhile the compatibility of lithium and organic solvents such as n-pentane is enhanced; the interference of impurities on the reaction can be eliminated in a high-purity state of the chlorinated tert-butane, byproducts such as lithium tert-butoxide are prevented from being generated, the moisture in the system is strictly limited by deep dehydration, a stable anhydrous environment is provided for synthesis of the tert-butyllithium, and the reaction efficiency is guaranteed; the operation of deep dehydration and impurity removal by activated aluminum oxide creates a high-cleanliness solvent system for the reaction, avoids the action of water and polar impurities with tert-butyllithium or reaction intermediates, and prevents product decomposition or impurity generation.

Description

Technical Field

[0001] This invention relates to the field of tert-butyllithium preparation technology, specifically to a method for preparing tert-butyllithium. Background Technology

[0002] Tert-butyllithium is an organometallic compound with strong alkalinity and high flammability. It can spontaneously combust in air, reacts violently with water and releases flammable gases. It must be stored and used under dry nitrogen protection. It can be used as a strong base and reagent in organic synthesis, to construct drug molecules containing non-neighboring heterocycles in drug synthesis, as an initiator in polymerization reactions to regulate polymer chain structure, and to prepare other lithium reagents.

[0003] In existing technologies, when lithium metal is used directly, its chemical activity is too high, and its reaction with tert-butane chloride is prone to instantaneous and violent local overheating and runaway reaction. Moreover, lithium metal is easily affected by water and oxygen, which degrades it, reducing its reactivity and product quality. Industrial-grade tert-butane chloride has insufficient purity and high water content, and is also prone to self-oxidation and decomposition. Water will cause tert-butyllithium to decompose, generating tert-butoxide impurities that can easily trigger side reactions. Industrial-grade n-pentane has high water content and many impurities, and the reaction system is easily affected by oxygen. Water and impurities will interfere with the reaction, and oxygen will oxidize tert-butyllithium.

[0004] Based on this, the present invention provides a method for preparing tert-butyllithium. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing tert-butyllithium. The tert-butyllithium prepared by this invention has high purity and yield, and the content of lithium tert-butoxide, a byproduct of the production process, is low.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing tert-butyllithium, comprising the following steps:

[0007] S1. Prepare modified lithium, tert-butane chloride, n-pentane, sodium, white oil, and n-hexane raw materials for later use;

[0008] S2. Argon gas is used to replace the reaction vessel. 16-20 parts of modified lithium, 1-3 parts of sodium and 100-120 parts of white oil are added. The temperature is raised to melt the modified lithium and sodium and stirred to make lithium sand. The lithium sand is washed with 200-240 parts of n-hexane multiple times to remove the white oil, thus completing the lithium treatment and oil washing operation.

[0009] S3. Fully replace the clean and dry reaction vessel with argon gas, add the lithium sand prepared in S2 and 100-120 parts of modified n-pentane, slowly heat to the specified temperature and then stop heating, add 3-7 parts of modified tert-butane chloride, and confirm the start of the reaction when the reflux is significantly increased.

[0010] S4. Slowly add 57-67 parts of modified n-pentane and 50-80 parts of modified tert-butyl chloride to the reactor at the set flow rate. During the addition process, take a sample every hour to detect the concentration of tert-butyllithium to ensure that the concentration rises steadily or does not fall, until the addition is completed.

[0011] S5. After the addition is complete, keep the temperature. After the temperature is complete, concentrate the reaction product under reduced pressure and take a sample to detect the molar concentration of the product. When the concentration is greater than 1.3M, it is determined as the reaction endpoint.

[0012] S6. After the reaction reaches its endpoint, the product is cooled to room temperature and injected into a settling vessel using argon gas. After standing, the supernatant is pumped into a transfer tank. Fresh modified n-pentane is added to the settling vessel to soak the residue. The supernatant is then pumped into another transfer tank for later use, thus completing the preparation of tert-butyllithium.

[0013] Preferably, the modified lithium is obtained by pretreatment, surface modification and stabilization treatment of metallic lithium.

[0014] Preferably, the preparation steps of the modified lithium are as follows: washing lithium particles with anhydrous ethanol 3-5 times, and then drying them in an oven to constant weight; adding the pretreated lithium particles to a silane coupling agent toluene solution, stirring at 50-60℃ for 1-2 hours, filtering after the reaction, and drying the filtered lithium particles in an oven at 80-90℃ for 1-1.5 hours to complete the surface modification of the modified lithium; adding the surface-modified lithium particles to a PVP anhydrous methanol solution, stirring at 40-50℃ for 0.5-1 hours, filtering after stirring, and drying the filtered lithium particles in an oven to constant weight to obtain modified lithium.

[0015] Preferably, the silane coupling agent is KH-550 with a concentration of 2-4%, and the mass ratio of lithium particles to solution is 1:(5-8); the PVP concentration is 1-3%, and the mass ratio of lithium particles to solution is 1:(4-6).

[0016] Preferably, the modified tert-butane chloride is prepared from industrial-grade tert-butane chloride through purification, dehydration treatment, and the addition of stabilizers.

[0017] Preferably, the preparation steps of the modified tert-butane chloride are as follows: industrial-grade tert-butane chloride is added to a distillation column and the distillation column parameters are controlled, and the top fraction is collected to complete the purification; the purified tert-butane chloride fraction is passed through a 4A molecular sieve adsorption column with a height of 1-1.5m, and the adsorption temperature and fraction flow rate are controlled to complete the dehydration treatment of the modified tert-butane chloride; a stabilizer is added to the dehydrated tert-butane chloride, and the mixture is stirred at 20-30℃ for 10-20min. After stirring, the mixture is sealed and stored to obtain the modified tert-butane chloride.

[0018] Preferably, the amount of molecular sieve used is 5-10% of the fraction mass; the stabilizer is p-tert-butylcatechol, and its addition amount is 0.01-0.03% of the mass of tert-butylchloroethane.

[0019] Preferably, the modified n-pentane is obtained from industrial-grade n-pentane through deep dehydration, impurity removal, and inertization treatment.

[0020] Preferably, the preparation steps of the modified n-pentane are as follows: industrial-grade n-pentane is added to a drying kettle, 2-5 nm of anhydrous calcium chloride is added, the mixture is stirred, allowed to stand and separate into layers, and the supernatant is taken to complete dehydration; the supernatant of the dehydrated n-pentane is passed through an activated alumina adsorption column with a height of 0.8-1.2 m, and the adsorption temperature and the flow rate of the supernatant are controlled to remove impurities; argon gas is introduced into the n-pentane after impurity removal for 30-60 min to perform inertization treatment to obtain modified n-pentane.

[0021] Preferably, the amount of anhydrous calcium chloride used is 3-5% of the mass of n-pentane; and the amount of activated alumina used is 4-8% of the mass of the supernatant.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. In this invention, after pretreatment, surface modification with a silane coupling agent, and PVP stabilization treatment, modified lithium achieves several advantages. First, the organic layer constructed on the lithium particle surface by the silane coupling agent weakens the excessive reactivity of lithium, preventing it from reacting violently with modified tert-butane chloride and causing local overheating and boiling, thus making the reaction rate easier to control precisely. Second, the pretreatment removes trace impurities from the lithium surface, and the PVP coating provides long-term protection against contact between water, oxygen, and lithium, preventing lithium from deteriorating during storage and the early stages of the reaction. It also enhances the compatibility of lithium with organic solvents such as n-pentane, allowing the lithium shavings obtained after lithium treatment to be more uniformly dispersed in the reaction system, ensuring consistent activity during subsequent reactions with modified tert-butane chloride, reducing side reactions, and ultimately improving the yield and purity of tert-butyllithium.

[0024] 2. In this invention, modified tert-butane is purified by distillation, deeply dehydrated, and stabilized. The high purity eliminates interference from impurities in the reaction, preventing the formation of byproducts such as lithium tert-butoxide. Tert-butyllithium readily decomposes in water; deep dehydration strictly limits the water content in the system, providing a stable anhydrous environment for its synthesis and ensuring reaction efficiency. The tert-butylcatechol stabilizer inhibits the oxidation and decomposition of tert-butane, extending its storage stability and preventing the introduction of additional impurities due to its own instability during reaction with modified lithium, ensuring the directional formation of tert-butyllithium. When used in conjunction with modified lithium and modified n-pentane, it participates in the reaction in a stable chemical state, significantly improving process reliability.

[0025] 3. In this invention, modified n-pentane undergoes deep dehydration, impurity removal, and inertization treatment. The deep dehydration and impurity removal with activated alumina create a highly clean solvent system for the reaction, preventing water and polar impurities from interacting with tert-butyllithium or reaction intermediates, thus preventing product decomposition or impurity generation. The inertization treatment effectively suppresses the oxidation risk of tert-butyllithium, preventing it from burning or decomposing upon contact with oxygen. Simultaneously, the argon atmosphere maintains an inert environment for the reaction system. Furthermore, the compatibility of modified n-pentane with modified lithium and modified tert-butyl chloride is significantly improved, enabling more uniform dispersion of reactants, optimizing the heat and mass transfer efficiency of the reaction system, and making the reaction rate and concentration distribution more stable. This allows for simultaneous improvement in the controllability of the entire tert-butyllithium preparation process and product quality. In synergy with auxiliary materials such as sodium and white oil, it ensures the high efficiency and stability of the preparation process. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application are described clearly and completely.

[0028] Example 1: A method for preparing tert-butyllithium, comprising the following steps:

[0029] S1. Prepare modified lithium, tert-butane chloride, n-pentane, sodium, white oil, and n-hexane raw materials for later use;

[0030] S2. Argon gas is used to replace the reaction vessel. 16 parts of modified lithium, 1 part of sodium and 100 parts of white oil are added. The temperature is raised to melt the modified lithium and sodium and stir to make lithium sand. The lithium sand is washed with 200 parts of n-hexane multiple times to remove the white oil, thus completing the lithium treatment and oil washing operation.

[0031] S3. Fully replace the clean and dry reaction vessel with argon gas, add the lithium sand prepared in S2 and 100 parts of modified n-pentane, slowly heat to the specified temperature and then stop heating, add 3 parts of modified tert-butane chloride, and confirm the start of the reaction when the reflux is significantly increased.

[0032] S4. Slowly add 57 parts of modified n-pentane and 50 parts of modified tert-butyl chlorobutane into the reactor at the set flow rate. During the addition process, take a sample every hour to detect the concentration of tert-butyllithium to ensure that the concentration rises steadily or does not fall, until the addition is completed.

[0033] S5. After the addition is complete, keep the temperature. After the temperature is complete, concentrate the reaction product under reduced pressure and take a sample to detect the molar concentration of the product. When the concentration is greater than 1.3M, it is determined as the reaction endpoint.

[0034] S6. After the reaction reaches its endpoint, the product is cooled to room temperature and injected into a settling vessel using argon gas. After standing, the supernatant is pumped into a transfer tank. Fresh modified n-pentane is added to the settling vessel to soak the residue. The supernatant is then pumped into another transfer tank for later use, thus completing the preparation of tert-butyllithium.

[0035] In reactor S3, the temperature is controlled at 30℃ and the pressure is controlled at atmospheric pressure. When the temperature reaches 38.5℃, an alarm is triggered and the feeding is slowed down. When the temperature reaches 39℃, the feeding is stopped. When the temperature reaches 40℃, the interlock stops the dripping of modified tert-chlorobutane and the refrigerant is turned on to cool down.

[0036] Modified lithium is prepared by pretreatment, surface modification and stabilization treatment of metallic lithium.

[0037] The preparation steps for modified lithium are as follows:

[0038] Step 1: Select bulk lithium metal, crush it into 1mm lithium particles, add the lithium particles to a stainless steel container and wash them 3 times with anhydrous ethanol, then put them in an oven and dry them at 105℃ to constant weight to complete the pretreatment of modified lithium.

[0039] Step 2: Add the pretreated lithium particles to a toluene solution of silane coupling agent and stir at 50°C for 1 hour. After the reaction is complete, filter the solution and place the filtered lithium particles in an oven to dry at 80°C for 1 hour to complete the surface modification of modified lithium.

[0040] Step 3: Add the surface-modified lithium particles to anhydrous methanol solution of PVP (polyvinylpyrrolidone). The concentration of PVP is 1%, and the mass ratio of lithium particles to solution is 1:4. Stir at 40°C for 0.5 hours. After stirring, filter the solution and place the filtered lithium particles in an oven to dry at 80°C until constant weight. This completes the stabilization treatment of the modified lithium, yielding modified lithium.

[0041] The silane coupling agent used is KH-550 with a concentration of 2%, and the mass ratio of lithium particles to solution is 1:5; the concentration of PVP (polyvinylpyrrolidone) is 1%, and the mass ratio of lithium particles to solution is 1:4.

[0042] Modified tert-butane chloride is prepared by purifying industrial-grade tert-butane chloride, dehydrating it, and adding a stabilizer.

[0043] The preparation steps for modified tert-chlorobutane are as follows:

[0044] Step 1: Add industrial-grade tert-chlorobutane to a distillation column, control the vacuum degree of the distillation column to 0.08 MPa, the top temperature of the column to 50℃, the bottom temperature of the column to 65℃, and the reflux ratio to 2:1. Collect the top fraction of the column to complete the purification of the modified tert-chlorobutane.

[0045] Step 2: Pass the purified tert-chlorobutane fraction through a 4A molecular sieve adsorption column with a column height of 1m, control the adsorption temperature at 20℃, and the fraction flow rate at 0.5L / min to complete the dehydration treatment of the modified tert-chlorobutane.

[0046] Step 3: Add a stabilizer to the dehydrated tert-butane chloride, stir at 20°C for 10 minutes, seal and store after stirring to obtain modified tert-butane chloride.

[0047] The amount of molecular sieve used is 5% of the fraction mass; the stabilizer is p-tert-butylcatechol, and its addition amount is 0.01% of the mass of tert-chlorobutane.

[0048] Modified n-pentane is obtained from industrial-grade n-pentane through deep dehydration, impurity removal, and inertization treatment.

[0049] The preparation steps for modified n-pentane are as follows:

[0050] Step 1: Add industrial-grade n-pentane to a drying kettle, add anhydrous calcium chloride with a particle size of 2 mm, control the temperature at 25℃, stir for 2 hours, let stand for 1 hour to separate the layers, take the upper clear liquid to complete the deep dehydration of modified n-pentane.

[0051] Step 2: Pass the supernatant of the deeply dehydrated n-pentane through an activated alumina adsorption column with a height of 0.8 m, an adsorption temperature of 20 ℃, and a flow rate of 1 L / min to remove impurities from the modified n-pentane.

[0052] Step 3: Introduce argon gas into the n-pentane after impurity removal, controlling the gas flow rate at 0.2 L / min and the gas flow time at 30 min, ensuring that the oxygen content in the n-pentane is ≤0.1% and the water content is ≤50 ppm, thus completing the inertization treatment and obtaining modified n-pentane.

[0053] The amount of anhydrous calcium chloride used is 3% of the mass of n-pentane; the amount of activated alumina used is 4% of the mass of the supernatant.

[0054] Example 2: Method for preparing tert-butyllithium, comprising the following steps:

[0055] S1. Prepare modified lithium, tert-butane chloride, n-pentane, sodium, white oil, and n-hexane raw materials for later use;

[0056] S2. Argon gas is used to replace the reaction vessel. 18 parts of modified lithium, 2 parts of sodium and 110 parts of white oil are added. The temperature is raised to melt the modified lithium and sodium and stir to make lithium sand. The lithium sand is washed with 220 parts of n-hexane multiple times to remove the white oil, thus completing the lithium treatment and oil washing operation.

[0057] S3. Fully replace the clean and dry reaction vessel with argon gas, add the lithium sand prepared in S2 and 110 parts of modified n-pentane, slowly heat to the specified temperature and then stop heating, add 5 parts of modified tert-butane chloride, and confirm the start of the reaction when the reflux is significantly increased.

[0058] S4. Slowly add 62 parts of modified n-pentane and 65 parts of modified tert-butyl chlorobutane into the reactor at the set flow rate. During the addition process, take a sample every hour to detect the concentration of tert-butyllithium to ensure that the concentration rises steadily or does not fall, until the addition is completed.

[0059] S5. After the addition is complete, keep the temperature. After the temperature is complete, concentrate the reaction product under reduced pressure and take a sample to detect the molar concentration of the product. When the concentration is greater than 1.3M, it is determined as the reaction endpoint.

[0060] S6. After the reaction reaches its endpoint, the product is cooled to room temperature and injected into a settling vessel using argon gas. After standing, the supernatant is pumped into a transfer tank. Fresh modified n-pentane is added to the settling vessel to soak the residue. The supernatant is then pumped into another transfer tank for later use, thus completing the preparation of tert-butyllithium.

[0061] In reactor S3, the temperature is controlled at 34℃ and the pressure is controlled at atmospheric pressure. When the temperature reaches 38.5℃, an alarm is triggered and the feeding is slowed down. When the temperature reaches 39℃, the feeding is stopped. When the temperature reaches 40℃, the interlock stops the dripping of modified tert-chlorobutane and the refrigerant is turned on to cool down.

[0062] Modified lithium is prepared by pretreatment, surface modification and stabilization treatment of metallic lithium.

[0063] The preparation steps for modified lithium are as follows:

[0064] Step 1: Select blocky lithium metal, crush it into 2mm lithium particles, add the lithium particles to a stainless steel container and wash them 4 times with anhydrous ethanol, then put them in an oven and dry them at 110℃ to constant weight to complete the pretreatment of modified lithium.

[0065] Step 2: Add the pretreated lithium particles to a toluene solution of silane coupling agent and stir at 55°C for 1.5 hours. After the reaction is complete, filter the solution and place the filtered lithium particles in an oven to dry at 85°C for 1.2 hours to complete the surface modification of modified lithium.

[0066] Step 3: Add the surface-modified lithium particles to anhydrous methanol solution of PVP (polyvinylpyrrolidone). The concentration of PVP is 2%, and the mass ratio of lithium particles to solution is 1:5. Stir at 45°C for 0.7 hours. After stirring, filter the solution and place the filtered lithium particles in an oven to dry at 85°C until constant weight. This completes the stabilization treatment of the modified lithium, yielding modified lithium.

[0067] The silane coupling agent used is KH-550 with a concentration of 3%, and the mass ratio of lithium particles to solution is 1:6.5; the concentration of PVP (polyvinylpyrrolidone) is 2%, and the mass ratio of lithium particles to solution is 1:5.

[0068] Modified tert-butane chloride is prepared by purifying industrial-grade tert-butane chloride, dehydrating it, and adding a stabilizer.

[0069] The preparation steps for modified tert-chlorobutane are as follows:

[0070] Step 1: Add industrial-grade tert-chlorobutane to a distillation column, control the vacuum degree of the distillation column to 0.085 MPa, the top temperature of the column to 51℃, the bottom temperature of the column to 67℃, and the reflux ratio to 2.5:1, collect the top fraction of the column, and complete the purification of modified tert-chlorobutane.

[0071] Step 2: Pass the purified tert-chlorobutane fraction through a 4A molecular sieve adsorption column with a column height of 1.2m, control the adsorption temperature at 25℃, and the fraction flow rate at 0.7L / min to complete the dehydration treatment of the modified tert-chlorobutane.

[0072] Step 3: Add a stabilizer to the dehydrated tert-butane chloride, stir at 25°C for 15 minutes, seal and store after stirring to obtain modified tert-butane chloride.

[0073] The molecular sieve was used at 7.5% of the fraction mass; the stabilizer was p-tert-butylcatechol, which was added at 0.02% of the mass of tert-chlorobutane.

[0074] Modified n-pentane is obtained from industrial-grade n-pentane through deep dehydration, impurity removal, and inertization treatment.

[0075] The preparation steps for modified n-pentane are as follows:

[0076] Step 1: Add industrial-grade n-pentane to a drying kettle, add anhydrous calcium chloride with a particle size of 3.5 mm, control the temperature at 30℃, stir for 2.5 h, let stand for 1.5 h to separate the layers, take the upper clear liquid to complete the deep dehydration of modified n-pentane;

[0077] Step 2: Pass the supernatant of the deeply dehydrated n-pentane through an activated alumina adsorption column with a column height of 1.0 m, an adsorption temperature of 25 ℃, and a supernatant flow rate of 1.2 L / min to complete the removal of impurities from the modified n-pentane.

[0078] Step 3: Introduce argon gas into the n-pentane after impurity removal, controlling the gas flow rate at 0.3 L / min and the gas flow time at 45 min, ensuring that the oxygen content in the n-pentane is ≤0.1% and the water content is ≤50 ppm, thus completing the inertization treatment and obtaining modified n-pentane.

[0079] The amount of anhydrous calcium chloride used is 4% of the mass of n-pentane; the amount of activated alumina used is 6% of the mass of the supernatant.

[0080] Example 3: A method for preparing tert-butyllithium, comprising the following steps:

[0081] S1. Prepare modified lithium, tert-butane chloride, n-pentane, sodium, white oil, and n-hexane raw materials for later use;

[0082] S2. Argon gas is used to replace the reaction vessel. 20 parts of modified lithium, 3 parts of sodium and 120 parts of white oil are added. The temperature is raised to melt the modified lithium and sodium and stir to make lithium sand. The lithium sand is washed with 240 parts of n-hexane multiple times to remove the white oil, thus completing the lithium treatment and oil washing operation.

[0083] S3. The clean and dry reactor is fully purged with argon gas. The lithium sand prepared in S2 and 120 parts of modified n-pentane are added. The temperature is slowly raised to the specified temperature and then heating is stopped. 7 parts of modified tert-butane chloride are added. When the reflux is significantly increased, the reaction is confirmed to have started.

[0084] S4. Slowly add 67 parts of modified n-pentane and 80 parts of modified tert-butyl chlorobutane into the reactor at the set flow rate. During the addition process, take a sample every hour to detect the concentration of tert-butyllithium to ensure that the concentration rises steadily or does not fall, until the addition is completed.

[0085] S5. After the addition is complete, keep the temperature. After the temperature is complete, concentrate the reaction product under reduced pressure and take a sample to detect the molar concentration of the product. When the concentration is greater than 1.3M, it is determined as the reaction endpoint.

[0086] S6. After the reaction reaches its endpoint, the product is cooled to room temperature and injected into a settling vessel using argon gas. After standing, the supernatant is pumped into a transfer tank. Fresh modified n-pentane is added to the settling vessel to soak the residue. The supernatant is then pumped into another transfer tank for later use, thus completing the preparation of tert-butyllithium.

[0087] In the S3 reactor, the temperature is controlled at 38℃ and the pressure is controlled at atmospheric pressure. When the temperature reaches 38.5℃, an alarm is triggered and the feeding is slowed down. When the temperature reaches 39℃, the feeding is stopped. When the temperature reaches 40℃, the interlock stops the dripping of modified tert-chlorobutane and the refrigerant is turned on to cool down.

[0088] Modified lithium is prepared by pretreatment, surface modification and stabilization treatment of metallic lithium.

[0089] The preparation steps for modified lithium are as follows:

[0090] Step 1: Select bulk lithium metal, crush it into 3mm lithium particles, add the lithium particles to a stainless steel container and wash them 5 times with anhydrous ethanol, then put them in an oven and dry them at 115℃ to constant weight to complete the pretreatment of modified lithium.

[0091] Step 2: Add the pretreated lithium particles to a toluene solution of silane coupling agent and stir at 60°C for 2 hours. After the reaction is complete, filter the solution and place the filtered lithium particles in an oven to dry at 90°C for 1.5 hours to complete the surface modification of modified lithium.

[0092] Step 3: Add the surface-modified lithium particles to anhydrous methanol solution of PVP (polyvinylpyrrolidone). The concentration of PVP is 3%, and the mass ratio of lithium particles to solution is 1:6. Stir at 50°C for 1 hour. After stirring, filter the solution and place the filtered lithium particles in an oven to dry at 90°C until constant weight. This completes the stabilization treatment of the modified lithium, yielding modified lithium.

[0093] The silane coupling agent used is KH-550 with a concentration of 4%, and the mass ratio of lithium particles to solution is 1:8; the concentration of PVP (polyvinylpyrrolidone) is 3%, and the mass ratio of lithium particles to solution is 1:6.

[0094] Modified tert-butane chloride is prepared by purifying industrial-grade tert-butane chloride, dehydrating it, and adding a stabilizer.

[0095] The preparation steps for modified tert-chlorobutane are as follows:

[0096] Step 1: Add industrial-grade tert-chlorobutane to a distillation column, control the vacuum degree of the distillation column to 0.09 MPa, the top temperature of the column to 52℃, the bottom temperature of the column to 70℃, and the reflux ratio to 3:1. Collect the top fraction of the column to complete the purification of the modified tert-chlorobutane.

[0097] Step 2: Pass the purified tert-chlorobutane fraction through a 4A molecular sieve adsorption column with a column height of 1.5m, control the adsorption temperature at 30℃, and the fraction flow rate at 1L / min to complete the dehydration treatment of the modified tert-chlorobutane.

[0098] Step 3: Add a stabilizer to the dehydrated tert-butane chloride, stir at 30°C for 20 minutes, seal and store after stirring to obtain modified tert-butane chloride.

[0099] The amount of molecular sieve used is 10% of the fraction mass; the stabilizer is p-tert-butylcatechol, and its addition amount is 0.03% of the mass of tert-chlorobutane.

[0100] Modified n-pentane is obtained from industrial-grade n-pentane through deep dehydration, impurity removal, and inertization treatment.

[0101] The preparation steps for modified n-pentane are as follows:

[0102] Step 1: Add industrial-grade n-pentane to a drying kettle, add anhydrous calcium chloride with a particle size of 5 mm, control the temperature at 35℃, stir for 3 hours, let stand for 2 hours to separate the layers, take the upper clear liquid to complete the deep dehydration of modified n-pentane.

[0103] Step 2: Pass the supernatant of the deeply dehydrated n-pentane through an activated alumina adsorption column with a column height of 1.2m, an adsorption temperature of 30℃, and a supernatant flow rate of 1.5L / min to remove impurities from the modified n-pentane.

[0104] Step 3: Introduce argon gas into the n-pentane after impurity removal, controlling the gas flow rate at 0.5 L / min and the gas flow time at 60 min, ensuring that the oxygen content in the n-pentane is ≤0.1% and the water content is ≤50 ppm, thus completing the inertization treatment and obtaining modified n-pentane.

[0105] The amount of anhydrous calcium chloride used is 5% of the mass of n-pentane; the amount of activated alumina used is 8% of the mass of the supernatant.

[0106] Comparative Example 1: The difference between this comparative example and Example 1 is that commercially available lithium is used in this comparative example.

[0107] Comparative Example 2 differs from Example 1 in that commercially available tert-chlorobutane is used in this comparative example.

[0108] Comparative Example 3 differs from Example 1 in that commercially available n-pentane is used in this comparative example.

[0109] Performance testing: Performance tests were conducted on the products prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3.

[0110] tert-butyllithium purity test: In an argon-protected glove box, inject the sample into a dry brown volumetric flask containing anhydrous n-pentane using an airtight syringe, dilute and shake well; use a DB-1 nonpolar capillary column, high-purity helium as carrier gas, split injection, hydrogen flame ionization detector, and programmed temperature rise; prepare gradient concentration solutions using tert-butyllithium standards of known purity to plot an external standard curve, inject diluted samples, and calculate the mass fraction of tert-butyllithium based on the characteristic peak area of ​​tert-butyllithium in the chromatogram and the standard curve to obtain the purity. Test according to: "Gas Chromatographic Analysis Procedure for Organic Synthesis Reagents";

[0111] Byproduct (lithium tert-butoxide) content test: In an argon-protected glove box, use an airtight syringe to take the tert-butyllithium reaction solution and inject it into a dry brown volumetric flask containing anhydrous acetonitrile. Seal and vortex for 1 min. Use a reverse-phase C18 column with methanol-0.05 mol / L potassium dihydrogen phosphate buffer as the mobile phase, UV detector, column temperature 30℃, and injection volume 10 μL. Prepare a series of solutions of 0.01-1.0 mg / mL using lithium tert-butoxide standard of known purity and plot the "concentration-peak area" external standard curve. Inject diluted samples under argon protection. Calculate the concentration of the diluted solution based on the characteristic peak area of ​​lithium tert-butoxide and the standard curve. Then convert the mass fraction of lithium tert-butoxide in the original reaction solution according to the dilution factor. Test standard: "Specification for the Detection of Hydroxyl Impurities in Organoalkali Metal Compounds".

[0112] tert-butyllithium yield test: First, extract the actual feed mass and purity of modified tert-butylchlorobutane from the production records, calculate the amount of substance based on its molar mass, and then calculate the theoretical yield based on the molar mass of tert-butyllithium; then, take the reaction endpoint product liquid under argon protection, measure the molar concentration of tert-butyllithium using the double titration method, read the total volume of the product by calibrating the level gauge and deduct the sampling loss, and calculate the actual yield according to "mass = concentration × volume × molar mass"; finally, calculate the result according to "yield = actual yield / theoretical yield × 100%", and the test is based on: "Specification for Calculation of Yield of Organic Synthesis Reaction".

[0113] The obtained test data are recorded in Table 1 below:

[0114]

[0115] By comparing and analyzing the relevant data in Table 1, it can be seen that the tert-butyllithium prepared by the method of the present invention not only has high purity and yield, but also low content of lithium tert-butoxide, a byproduct in the production process. This indicates that the tert-butyllithium preparation method provided by the present invention has a broader market prospect and is more suitable for promotion.

[0116] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0117] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing tert-butyllithium, characterized in that, Includes the following steps: S1. Prepare modified lithium, tert-butane chloride, n-pentane, sodium, white oil, and n-hexane raw materials for later use; S2. Argon gas is used to replace the reaction vessel. 16-20 parts of modified lithium, 1-3 parts of sodium and 100-120 parts of white oil are added. The temperature is raised to melt the modified lithium and sodium and stirred to make lithium sand. The lithium sand is washed with 200-240 parts of n-hexane multiple times to remove the white oil, thus completing the lithium treatment and oil washing operation. S3. Fully replace the clean and dry reaction vessel with argon gas, add the lithium sand prepared in S2 and 100-120 parts of modified n-pentane, slowly heat to the specified temperature and then stop heating, add 3-7 parts of modified tert-butane chloride, and confirm the start of the reaction when the reflux is significantly increased. S4. Slowly add 57-67 parts of modified n-pentane and 50-80 parts of modified tert-butyl chloride to the reactor at the set flow rate. During the addition process, take a sample every hour to detect the concentration of tert-butyllithium to ensure that the concentration rises steadily or does not fall, until the addition is completed. S5. After the addition is complete, keep the temperature. After the temperature is complete, concentrate the reaction product under reduced pressure and take a sample to detect the molar concentration of the product. When the concentration is greater than 1.3M, it is determined as the reaction endpoint. S6. After the reaction reaches its endpoint, the product is cooled to room temperature and injected into a settling vessel using argon gas. After standing, the supernatant is pumped into a transfer tank. Fresh modified n-pentane is added to the settling vessel to soak the residue. The supernatant is then pumped into another transfer tank for later use, thus completing the preparation of tert-butyllithium.

2. The method for preparing tert-butyllithium according to claim 1, characterized in that: The modified lithium is obtained by pretreatment, surface modification and stabilization treatment of metallic lithium.

3. The method for preparing tert-butyllithium according to claim 1, characterized in that, The preparation steps of the modified lithium are as follows: Lithium particles are washed with anhydrous ethanol 3-5 times and then dried in an oven to constant weight; the pretreated lithium particles are added to a silane coupling agent toluene solution and stirred at 50-60℃ for 1-2 hours. After the reaction is completed, the mixture is filtered, and the filtered lithium particles are placed in an oven and dried at 80-90℃ for 1-1.5 hours to complete the surface modification of the modified lithium; the surface-modified lithium particles are added to a PVP anhydrous methanol solution and stirred at 40-50℃ for 0.5-1 hours. After stirring is completed, the mixture is filtered, and the filtered lithium particles are placed in an oven and dried to constant weight to obtain modified lithium.

4. The method for preparing tert-butyllithium according to claim 3, characterized in that: The silane coupling agent used is KH-550, with a concentration of 2-4%, and the mass ratio of lithium particles to solution is 1:(5-8); the PVP concentration is 1-3%, and the mass ratio of lithium particles to solution is 1:(4-6).

5. The method for preparing tert-butyllithium according to claim 1, characterized in that: The modified tert-butane chloride is prepared by purifying industrial-grade tert-butane chloride, dehydrating it, and adding a stabilizer.

6. The method for preparing tert-butyllithium according to claim 1, characterized in that, The preparation steps of the modified tert-butane chloride are as follows: industrial-grade tert-butane chloride is added to a distillation column and the distillation column parameters are controlled to collect the top fraction for purification; the purified tert-butane chloride fraction is passed through a 4A molecular sieve adsorption column with a height of 1-1.5m, and the adsorption temperature and fraction flow rate are controlled to complete the dehydration treatment of the modified tert-butane chloride; a stabilizer is added to the dehydrated tert-butane chloride, and the mixture is stirred at 20-30℃ for 10-20 minutes. After stirring, the mixture is sealed and stored to obtain the modified tert-butane chloride.

7. The method for preparing tert-butyllithium according to claim 6, characterized in that: The amount of molecular sieve used is 5-10% of the fraction mass; the stabilizer is p-tert-butylcatechol, and its addition amount is 0.01-0.03% of the mass of tert-butylchloroethane.

8. The method for preparing tert-butyllithium according to claim 1, characterized in that: The modified n-pentane is obtained from industrial-grade n-pentane through deep dehydration, impurity removal, and inertization treatment.

9. The method for preparing tert-butyllithium according to claim 1, characterized in that, The preparation steps of the modified n-pentane are as follows: industrial-grade n-pentane is added to a drying kettle, 2-5 nm of anhydrous calcium chloride is added, the mixture is stirred, allowed to stand and separate into layers, and the supernatant is taken to complete dehydration; the supernatant of the dehydrated n-pentane is passed through an activated alumina adsorption column with a height of 0.8-1.2 m, and the adsorption temperature and the flow rate of the supernatant are controlled to remove impurities; argon gas is introduced into the n-pentane after impurity removal for 30-60 min to inertize it, thereby obtaining the modified n-pentane.

10. The method for preparing tert-butyllithium according to claim 9, characterized in that: The amount of anhydrous calcium chloride used is 3-5% of the mass of n-pentane; the amount of activated alumina used is 4-8% of the mass of the supernatant.

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