Production method of stable liquid aluminum isopropoxide

Abstract

The invention discloses a production method of stable liquid aluminum isopropoxide, and belongs to the field of organic metal compound preparation. According to the method, an oxidation film on the surface of aluminum and water in isopropanol are removed through raw material pretreatment, and initial liquid aluminum isopropoxide is prepared in an inert atmosphere; the composite solvent is prepared by mixing a functional main solvent and a high-boiling-point auxiliary solvent in proportion, the addition amount of the composite solvent is 15-30% of that of the initial product, and the finished product is obtained through step-by-step stirring and mixing and precise filtration. Through double mechanisms of chemical coordination stabilization and physical volatilization inhibition, the problems of short shelf life and poor stability of the existing product are solved, the shelf life reaches 6-12 months, the purity is greater than or equal to 99.0%, the batch difference is less than or equal to + / -10%, and the preparation method has a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic metal compound preparation, and specifically provides a production method of stable liquid aluminum isopropoxide. BACKGROUND

[0002] Aluminum isopropoxide is an important organic aluminum intermediate and is widely used in the fields of catalysts, ceramic precursors and organic synthesis. Liquid aluminum isopropoxide is preferred in industrial production due to its good flowability and easy metering. However, the existing production method of liquid aluminum isopropoxide has many problems, resulting in poor stability and short shelf life.

[0003] In the prior art, liquid aluminum isopropoxide is usually a high-concentration system (effective component 80-90%) with short intermolecular distance, high collision probability of Al-O-Al bridge bond condensation reaction (polymerization) and aluminum center and trace water / oxygen, and is prone to hydrolysis, oxidation and polymerization. The hydrolysis reaction generates aluminum hydroxide precipitate, resulting in turbidity and stratification of the system; the oxidation reaction reduces the purity and affects the catalytic activity; and the polymerization reaction causes the viscosity to increase sharply and even solidify, which cannot be directly used.

[0004] To improve the stability of liquid aluminum isopropoxide, the conventional method is to add solvent for dilution, but there are obvious limitations. On the one hand, conventional solvents such as isopropyl alcohol can only inhibit the reaction by physical dilution and cannot solve the inherent high reactivity of the aluminum center. When the solvent is added to a certain extent (such as ≥30%), the stability improvement tends to slow down, and the shelf life is at most extended to 4-5 months, which is difficult to break through 6 months. On the other hand, excessive addition of low-boiling-point solvents will cause solvent evaporation during storage, causing the concentration of the system to rise, accelerating the deterioration in the later stage, such as the concentration rising from 60% to 75% after 3 months, and the stability sharply decreasing.

[0005] Therefore, there is an urgent need for a production method that can effectively improve the stability of liquid aluminum isopropoxide and extend the shelf life to 6-12 months. SUMMARY

[0006] In view of this, the present application provides a production method of stable liquid aluminum isopropoxide, which realizes the target of 6-12 months of shelf life of liquid aluminum isopropoxide by using functional composite solvents and controlling specific process conditions.

[0007] The technical scheme of the present application is as follows: the present application provides a production method of stable liquid aluminum isopropoxide, which comprises the following steps: (1) Raw material pretreatment: removing the surface oxide film of the aluminum raw material to obtain clean aluminum raw material; and deeply dehydrating isopropyl alcohol to make the water content ≤10ppm; (2) Reaction preparation: clean aluminum raw material and dehydrated isopropyl alcohol are reacted under the condition of inert gas atmosphere and 60-80℃, and 0.1-0.5% anhydrous aluminum chloride catalyst is added, the reaction time is 3-5 hours, and the initial liquid aluminum isopropyl alcohol is obtained; (3) Solvent preparation: the functional main solvent is mixed with the high-boiling auxiliary solvent at a mass ratio of 7:3 to prepare a composite solvent; the functional main solvent is methoxy propanol or diethylene glycol dimethyl ether, and the high-boiling auxiliary solvent is isooctanol; (4) Solvent addition: the composite solvent is added to the initial liquid aluminum isopropyl alcohol obtained in step (2), the addition amount of the composite solvent is 15-30% of the mass of the initial liquid aluminum isopropyl alcohol, and the mixture is stirred under the condition of inert gas atmosphere and 30-60℃ for 30-60 minutes, wherein the initial liquid aluminum isopropyl alcohol is first stirred with the functional main solvent at 60℃ for 30 minutes, and then the high-boiling auxiliary solvent is added after the temperature is lowered to 30℃; (5) Post-processing: the mixture obtained in step (4) is subjected to 0.1 μm precision filtration to obtain stable liquid aluminum isopropyl alcohol.

[0008] In some embodiments, in step (1), the specific way of removing the surface oxide film of the aluminum raw material is to etch with dilute hydrochloric acid and then vacuum dry.

[0009] In some embodiments, in step (1), the way of deep dehydration treatment of isopropyl alcohol is to use 3A molecular sieve drying.

[0010] In some embodiments, the inert gas in steps (2) and (4) is nitrogen or argon, and the oxygen content is ≤50 ppm.

[0011] In some embodiments, in step (3), the functional main solvent is subjected to molecular modification treatment, specifically, methoxy propanol is treated with trimethylchlorosilane to block part of the hydroxyl activity, further reducing the competitive reaction with the aluminum center.

[0012] In some embodiments, in step (3), the specific steps of modification treatment include: Pretreatment stage Solvent drying: take methoxy propanol (purity ≥99.5%), soak with 3A molecular sieve, and dehydrate to ≤5 ppm of water content; Equipment preparation: the reaction kettle (with stirring, condenser tube, dropping funnel) is vacuum dried at 120℃ for 2 hours, and then high-purity nitrogen gas (oxygen content ≤30 ppm) is introduced to replace 3 times after cooling to ensure no water and no oxygen.

[0013] 2. Silica etherization reaction Order of adding materials: 1. Add 1000g of dried methoxy propanol to the reaction kettle; 2. Add acid-binding agent (such as triethylamine), the amount is 1.1 times the molar amount of methoxypropanol (neutralize the HCl generated in the reaction, avoid corrosion of equipment and promote the forward reaction); 3. Start stirring and cool the system to 0-5°C; 4. Slowly add trimethylchlorosilane through a dropping funnel, the amount is 1.05 times the molar amount of methoxypropanol, and the drop time is controlled within 1-2 hours.

[0014] Reaction conditions: After the drop is completed, warm up to 25-30°C and continue stirring for 4-6 hours (monitor by gas chromatography, and terminate the reaction when the residual methoxypropanol is ≤1%);

[0015] 3. Post-treatment Filter out the salt: After the reaction is completed, a precipitate of triethylamine hydrochloride is generated in the system, which is filtered out with a 0.2 μm polytetrafluoroethylene filter membrane to remove solid impurities; Distillation purification: Distill the filtrate under reduced pressure (vacuum degree ≤500 Pa, temperature 60-70°C) to collect the distillate (mainly the modified methoxypropanol, i.e. methoxypropyl trimethylsilylether) and remove unreacted TMSCl and triethylamine; Moisture detection: After distillation, take a sample for detection to ensure that the moisture content of the treated solvent is ≤10 ppm.

[0016] After the hydroxyl group is blocked by silyletherification, only the oxygen atom on the ether bond of methoxypropanol remains to coordinate with the aluminum center (avoiding the strong competitive binding of the hydroxyl group), which not only maintains the chemical stability of the functional solvent but also eliminates the interference of the hydroxyl group to the aluminum center, thereby improving the synergistic effect of the composite solvent by 40-50% and providing core support for achieving a 12-month shelf life.

[0017] When the main solvent is diethylene glycol dimethyl ether, it can be treated by dehydration, peroxide removal and rectification purification.

[0018] Specifically, take diethylene glycol dimethyl ether (industrial grade, purity ≥99%), add 5% (mass ratio) of 3A molecular sieves, and stir for 24 hours under a nitrogen atmosphere to dehydrate the water content to ≤5 ppm; Add 0.5-1% (mass ratio) of anhydrous sodium sulfite (reducing impurity remover) to the dehydrated solvent, stir at 60°C for 2 hours to remove possible peroxides (peroxides can oxidize the aluminum center, causing the product to discolor); Perform vacuum rectification (vacuum degree ≤100 Pa, distillation range 162-163°C / normal pressure corresponding value) under nitrogen protection, intercept the middle fraction (70-80% of the total amount), remove low-boiling substances (such as methanol and dimethyl ether) and high-boiling substances (such as oligomers), and ensure a purity of ≥99.9%; The purified diethylene glycol dimethyl ether is stored in a stainless steel tank under nitrogen protection (oxygen content is less than or equal to 30 ppm) to avoid contact with air to reintroduce moisture or oxygen.

[0019] In some embodiments, in step (4), the amount of the added composite solvent is 20-25% of the mass of the initial liquid aluminum isopropoxide.

[0020] In some embodiments, in step (4), the functional main solvent accounts for 15-25% of the mass percentage of the composite solvent.

[0021] In some embodiments, in step (4), the functional main solvent accounts for 18% of the mass percentage of the composite solvent.

[0022] The principle of the present application is as follows: the functional main solvent methoxypropanol or diethylene glycol dimethyl ether contains "oxygen lone pair electrons" in the molecule, which can form a weak coordination bond with the aluminum center (Al 3+ ), thereby reducing the reactivity of the aluminum center through chemical action and inhibiting the hydrolysis and polymerization reactions. The high-boiling auxiliary solvent isooctanol has a high boiling point and low volatility, which can effectively reduce the volatilization of the solvent during storage and avoid the decrease in stability caused by the increase in the concentration of the system.

[0023] The composite solvent is added in a specific ratio and mixed by step stirring. The functional main solvent is first fully reacted with the initial liquid aluminum isopropoxide at 60°C to promote the formation of coordination bonds, and then the high-boiling auxiliary solvent is added after cooling to avoid volatilization of the auxiliary solvent at high temperature and ensure accurate proportioning. At the same time, the entire process is carried out in an inert gas atmosphere to isolate air and moisture, further ensuring the stability of the product The present application has the following beneficial effects relative to the prior art: The production method of stable liquid aluminum isopropoxide provided by the present application optimizes the functional composite solvent and the 15-30% solvent addition ratio, cooperates with raw material deep purification, inert atmosphere control, and precision filtration process, not only significantly extends the shelf life of the product to 6-12 months, but also solves the industry contradiction between "stabilization and activity retention", improves the product purity and batch stability, and reduces the comprehensive cost through the simplified pretreatment process of diethylene glycol dimethyl ether, normal temperature storage, and anti-volatility characteristics. Through the dual mechanism of "chemical coordination + physical inhibition", the traditional "simple dilution" cognition is broken through, and the method has good application prospects. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0025] 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 embodiments of the application belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications that are herein incorporated by reference, the definitions set forth in this section prevail over the definitions that are incorporated herein by reference.

[0026] The methods used in the following examples are conventional unless otherwise stated. The materials, reagents and instruments used are conventional unless otherwise stated, and are available to those skilled in the art through commercial channels.

[0027] When a range, preferably a range or a series of upper preferred values and lower preferred values is used to express an equivalent, concentration or other value or parameter, it should be understood that all ranges formed by any pairing of an upper range limit or preferred value with any lower range limit or preferred value, whether or not the range is expressly disclosed, are specifically disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within that range. In the specification and claims of this application, range limitations can be combined and / or interchanged, unless otherwise stated, and the ranges include all sub-ranges contained therein.

[0028] Example 1 (1) Raw material pretreatment: Take aluminum powder, etch the surface oxide film with dilute hydrochloric acid, and then vacuum dry to obtain clean aluminum powder; dry isopropyl alcohol with 3A molecular sieves to make the water content 8 ppm; (2) Reaction preparation: React clean aluminum powder with dehydrated isopropyl alcohol under the condition of nitrogen atmosphere (oxygen content 40 ppm) and 70°C, add 0.3% anhydrous aluminum chloride catalyst, the reaction time is 4 hours, to obtain initial liquid isopropyl aluminum; (3) Solvent blending: After treating methoxypropanol with trimethylchlorosilane, mix it with isooctanol according to the mass ratio of 7:3 to prepare a composite solvent, wherein the mass percentage of methoxypropanol in the composite solvent is 15%. (4) Solvent addition: 15% of the complex solvent is added to the initial liquid isopropyl alcohol aluminum obtained in step (2), and the initial liquid isopropyl alcohol aluminum is first stirred with methoxypropanol at 60°C for 30 minutes under a nitrogen atmosphere (oxygen content 40 ppm), then cooled to 30°C, and isooctanol is added, and stirring is continued for 30 minutes; (5) Post-treatment: The mixture obtained in step (4) is subjected to 0.1 μm precision filtration to obtain stable liquid isopropyl alcohol aluminum.

[0029] In the above (3), the method for treating methoxypropanol with trimethylchlorosilane includes: In a 500 mL three-necked flask under nitrogen protection, 200 g of methoxypropanol (purity ≥ 99.5%) and 15 g of triethylamine (catalyst) are added, and stirring is performed to raise the temperature to 55°C. 80 g of trimethylchlorosilane (purity ≥ 99%) is slowly added dropwise, and the dropping speed is controlled so that the reaction temperature does not exceed 60°C. After the addition is completed, the temperature is raised to 75°C to reflux for 4 hours. After the reaction is completed, the temperature is cooled to room temperature, and the generated ammonium chloride precipitate is removed by filtration. The filtrate is distilled under reduced pressure (vacuum degree -0.095 MPa), and the 120-125°C fraction is collected to obtain silicon etherified methoxypropanol (hydroxyl blocking rate ≥ 90%, confirmed by nuclear magnetic hydrogen spectrum).

[0030] Pre-treatment of high-boiling-point auxiliary solvent (isooctanol) 100 g of isooctanol is added to a 250 mL flask, 10 g of 3A molecular sieve (activated at 300°C for 4 hours) is added, and stirring is performed at room temperature for 24 hours to remove water. The molecular sieve is removed by filtration to obtain isooctanol with a water content of ≤ 10 ppm.

[0031] Mixing of complex solvent Under nitrogen protection, the prepared silicon etherified methoxypropanol (70 g) and the obtained isooctanol (30 g) are added to a 100 mL glass container, and stirring is performed at a speed of 200 rpm for 30 minutes to form a uniform transparent complex solvent. During the mixing process, a slight positive pressure (0.01 MPa) is maintained in the container to avoid air entering.

[0032] Example 2 (1) Raw material pre-treatment: clean aluminum foil is obtained by etching the surface oxide film of aluminum foil with dilute hydrochloric acid and vacuum drying; isopropanol is dried using 3A molecular sieve to have a water content of 5 ppm; (2) Reaction preparation: clean aluminum foil and dried isopropanol are reacted under an argon atmosphere (oxygen content 30 ppm) at 60°C with the addition of 0.1% anhydrous aluminum chloride catalyst, and the reaction time is 5 hours to obtain initial liquid isopropyl alcohol aluminum; (3) Solvent blending: the prepared diethylene glycol dimethyl ether (70 g) and the prepared isooctanol (30 g) were mixed in a 100 mL glass container under nitrogen protection, and stirred at a speed of 200 rpm for 30 minutes to form a uniform and transparent composite solvent. During the mixing process, a slight positive pressure (0.01 MPa) was maintained in the container to prevent air from entering. (4) Solvent addition: the prepared initial liquid isopropyl alcohol aluminum was added with the composite solvent, and the addition amount of the composite solvent was 22% of the mass of the initial liquid isopropyl alcohol aluminum. Under an argon atmosphere (oxygen content 30 ppm), the initial liquid isopropyl alcohol aluminum was first stirred with diethylene glycol dimethyl ether at 60°C for 30 minutes, then cooled to 30°C and added with isooctanol, and continued to stir for 45 minutes; (5) Post-treatment: the mixture obtained in step (4) was subjected to 0.1 μm precision filtration to obtain stable liquid isopropyl alcohol aluminum.

[0033] Preparation of diethylene glycol dimethyl ether: In a 250 mL flask under nitrogen protection, 150 g of diethylene glycol dimethyl ether (purity ≥ 99%) and 15 g of calcium hydride (drying agent) were added, heated to 60°C and refluxed and stirred for 8 hours. After cooling to room temperature, the solid was removed by filtration, and the filtrate was distilled under reduced pressure (vacuum degree -0.098 MPa). The fraction collected at 162-165°C was diethylene glycol dimethyl ether with a water content of ≤5 ppm.

[0034] Pre-treatment of high-boiling auxiliary solvent (isooctanol) The same as Example 1 Mixing of composite solvent Under nitrogen protection, the prepared diethylene glycol dimethyl ether (70 g) and the prepared isooctanol (30 g) were added to a 100 mL glass container, and stirred at a speed of 200 rpm for 30 minutes to form a uniform and transparent composite solvent. During the mixing process, a slight positive pressure (0.01 MPa) was maintained in the container to prevent air from entering.

[0035] Example 3 (1) Raw material pretreatment: clean aluminum powder was obtained by etching the surface oxide film of aluminum powder with dilute hydrochloric acid and vacuum drying; isopropyl alcohol was dried using 3A molecular sieves to a water content of 10 ppm; (2) Reaction preparation: clean aluminum powder and dehydrated isopropyl alcohol were reacted under a nitrogen atmosphere (oxygen content 50 ppm) at 80°C with the addition of 0.5% anhydrous aluminum chloride catalyst, and the reaction time was 3 hours to obtain initial liquid isopropyl alcohol aluminum; (3) Solvent blending: the prepared diethylene glycol dimethyl ether (70 g) and the prepared isooctanol (30 g) were mixed in a 100 mL glass container under nitrogen protection, and stirred at a speed of 200 rpm for 30 minutes to form a uniform and transparent composite solvent. During the mixing process, a slight positive pressure (0.01 MPa) was maintained in the container to prevent air from entering. (4) Solvent addition: 30% of the mass of the initial liquid aluminum isopropoxide is added to the complex solvent, and the initial liquid aluminum isopropoxide is stirred at 60°C for 30 minutes under a nitrogen atmosphere (oxygen content 50 ppm), then cooled to 30°C, and isooctanol is added, and stirring is continued for 60 minutes; (5) Post-treatment: the mixture obtained in step (4) is subjected to 0.1 μm precision filtration to obtain stable liquid aluminum isopropoxide.

[0036] The method for treating methoxypropanol with trimethylchlorosilane is the same as in Example 1, and the preparation of isooctanol and the mixed solvent is the same as in Example 1.

[0037] Comparative Example 1 The same procedure as in Example 2 is used, but no complex solvent is used, and the solvent is only isopropanol, and the amount added is 22% of the mass of the initial liquid aluminum isopropoxide.

[0038] Comparative Example 2 The same procedure as in Example 1 is used, but the mass ratio of methoxypropanol to isooctanol in the complex solvent is 5:5, the mass percentage of methoxypropanol in the complex solvent is 18%, and the amount of the complex solvent added is 22% of the mass of the initial liquid aluminum isopropoxide. The other steps are the same as in Example 1. Comparative Example 3 On the basis of Example 1, no complex solvent is used, and the original liquid aluminum isopropoxide prepared in step (2) is directly sealed in a glass container.

[0039] Comparative Example 4 On the basis of Example 1, the amount of the main solvent is changed to 20%, and the other conditions are the same as in Example 1.

[0040] Comparative Example 5 On the basis of Example 1, unmodified methoxypropanol is used, and the other conditions are the same as in Example 1.

[0041] The liquid aluminum isopropoxide obtained in Examples 1-3 and Comparative Examples 1-5 is subjected to stability testing, and is stored at 25°C, and its state, purity and annual change are observed regularly, and the results are as follows:

[0042] From the above results, the liquid isopropyl aluminum prepared in examples 1-3 of the present application can maintain a clear state without precipitation, has a high purity retention rate, small viscosity fluctuation, a shelf life of 6-12 months, and good stability after 6-12 months of storage. The stability of comparative example 1 is poor because it uses the conventional solvent isopropyl alcohol; the stability of comparative example 2 is not as good as that of the examples of the present application because the proportion of the composite solvent does not meet the requirements of the present application; the stability of comparative example 3 is the worst because it directly uses the original liquid isopropyl aluminum, which deteriorates easily. Comparative example 4 has a slight turbidity after 6 months and a significant decrease in stability after 12 months, proving that the specific proportion of the composite solvent is crucial to the effect. Comparative example 5 has turbidity after 6 months and severe deterioration after 12 months, confirming that the "silicon etherification modification" is the key process to maintain stability.

[0043] The above description is merely preferred embodiments of the present application but not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the protection scope of the present application.

Claims

1. A method for producing stable liquid aluminum isopropoxide, characterized in that, Includes the following steps: (1) Raw material pretreatment: The aluminum raw material is subjected to surface oxide film removal treatment to obtain clean aluminum raw material; the isopropanol is subjected to deep dehydration treatment to make the moisture content ≤10ppm; (2) Reaction preparation: Clean aluminum raw material and dehydrated isopropanol are reacted with 0.1-0.5% anhydrous aluminum trichloride catalyst in an inert gas atmosphere at 60-80℃ for 3-5 hours to obtain initial liquid aluminum isopropoxide; (3) Solvent preparation: The functional main solvent and the high-boiling-point auxiliary solvent are mixed at a mass ratio of 7:3 to obtain a composite solvent; the functional main solvent is methoxypropanol or diethylene glycol dimethyl ether, and the high-boiling-point auxiliary solvent is isooctyl alcohol; (4) Solvent addition: Add composite solvent to the initial liquid aluminum isopropoxide obtained in step (2). The amount of composite solvent added is 15-30% of the mass of the initial liquid aluminum isopropoxide. Stir and mix for 30-60 minutes under an inert gas atmosphere and at 30-60°C. First, stir the initial liquid aluminum isopropoxide and the functional main solvent at 60°C for 30 minutes, and then cool down to 30°C and add the high-boiling-point auxiliary solvent. (5) Post-processing: The mixture obtained in step (4) is subjected to 0.1μm precision filtration to obtain stable liquid aluminum isopropoxide.

2. The method for producing stable liquid aluminum isopropoxide as described in claim 1, characterized in that, In step (1), the specific method for removing the surface oxide film from the aluminum raw material is to etch it with dilute hydrochloric acid and then vacuum dry it.

3. The method for producing stable liquid aluminum isopropoxide as described in claim 1, characterized in that, In step (1), the method for deep dehydration of isopropanol is to use 3A molecular sieve drying.

4. The method for producing stable liquid aluminum isopropoxide as described in claim 1, characterized in that, The inert gas in steps (2) and (4) is nitrogen or argon, and the oxygen content is ≤50ppm.

5. The method for producing stable liquid aluminum isopropoxide as described in claim 1, characterized in that, In step (3), the functional main solvent is molecularly modified, specifically by treating methoxypropanol with trimethylchlorosilane.

6. The method for producing stable liquid aluminum isopropoxide as described in claim 1, characterized in that, In step (4), the amount of composite solvent added is 20-25% of the initial mass of liquid aluminum isopropoxide.

7. The method for producing stable liquid aluminum isopropoxide as described in claim 1, characterized in that, In step (4), the functional main solvent accounts for 15-25% of the mass percentage of the composite solvent.

8. The method for producing stable liquid aluminum isopropoxide as described in claim 1, characterized in that, In step (4), the functional main solvent accounts for 18% of the mass percentage of the composite solvent.

Images