JP3225564B2 - Manufacturing method of aluminum alkoxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing aluminum alkoxide. More specifically, the present invention relates to a method for producing aluminum alkoxide by a solid-liquid reaction between metal aluminum and an alcohol, wherein the reaction rate is remarkably improved.

[0002]

2. Description of the Prior Art Aluminum alkoxide is used as an organic synthesis catalyst, a dehydration condensing agent, a surface treatment agent, a modifying additive such as paint, ink, adhesive, or a water repellent.
Further, in recent years, it has been widely used as a raw material for functional glass and alumina-based fine ceramic powder by a sol-gel method.

[0003] The following two methods are generally known as methods for synthesizing aluminum alkoxide.

1) AlX ₃ + 3ROH → Al (OR) ₃ + 3HX 2) Al + 3ROH → Al (OR) ₃ + 3 / 2H ₂ [In the formula, R represents a hydrocarbon group, and X represents a halogen group such as chlorine. ]

The method 1) is a reaction between an aluminum halide such as aluminum chloride and an alcohol, but has a drawback that hydrogen halide gas such as hydrochloric acid is generated as a by-product, thereby causing corrosion of the apparatus.

On the other hand, the method 2) is a reaction between metal aluminum and an alcohol. Generally, the reaction is slow. Therefore, mercuric chloride or the like for the purpose of etching an oxide film of metal aluminum is used as a reaction initiation accelerator. The method of adding is used. However, as is well known, mercuric chloride is toxic and has problems in handling.

[0007]

In view of such circumstances,
The present inventors have conducted intensive studies to improve the reaction rate in a method that does not have the above-mentioned problems in a method for producing aluminum alkoxide by a reaction between metal aluminum and an alcohol. It has been found that when a specific trace component is present, the reactivity between metal aluminum and alcohol is significantly improved, and the present invention has been completed.

[0008]

Means for Solving the Problems That is, the present invention provides a process for preparing aluminum alkoxide by solid-liquid reaction between metal aluminum and an alcohol, gallium also
Is a method for producing aluminum alkoxide, characterized in that at least one compound of indium is present in the liquid phase in an amount of 0.02 to 50 ppm (in terms of metal), and a solid-liquid reaction between metal aluminum and alcohol is carried out. To offer.

Hereinafter, the method of the present invention will be described in more detail. A feature of the present invention resides in performing a solid-liquid reaction in the presence of a specific amount of gallium, indium or a compound of these metals in a solid-liquid reaction between metal aluminum and an alcohol.

The amount of at least one gallium, indium or compound of these metals present in the reaction liquid phase is:
The metal concentration of gallium and indium in the reaction liquid phase in contact with the metallic aluminum is 0.02 to 50.
ppm, preferably 0.1 to 40 ppm.

If the metal concentration in the solution is less than 0.02 ppm, no reaction promoting effect is observed, while if it exceeds 50 ppm, the reaction promoting effect is saturated, and the produced aluminum alkoxide is converted into fine particles such as high-purity alumina. When used as a raw material of ceramic powder, gallium and indium migrate as impurities into the final product, causing inconvenience such as deterioration of sinterability and optical characteristics.

The gallium and indium compounds used in the present invention include alkoxide compounds such as methoxide, ethoxide and isopropoxide;
Allyloxide compounds such as phenoxide, carboxylate compounds such as formate and acetate, acetylacetonate compounds, and the like are used alone or in combination with anhydrous halides such as chlorides that are soluble in the raw alcohol or other solvent used. Can be used.

The method for allowing these metals or metal compounds to be present in the reaction liquid phase is not particularly limited, as long as the method allows the presence of a predetermined concentration in the reaction liquid phase. From the viewpoint of exhibiting the accelerating effect, gallium or indium or a compound of these metals is previously mixed and dispersed in metallic aluminum by a known method such as previously dispersing or dissolving.
A method of reacting metal aluminum with an alcohol while dispersing or eluting these metals or compounds of these metals in a liquid phase during the reaction is suitably used.

Of course, the desired amounts of gallium and indium are as follows:
They may be used together in consideration of the amount eluted from the metallic aluminum and the amount added directly into the liquid phase.

The alcohol as a raw material for forming the liquid phase is a monohydric alcohol having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, and more specifically, methyl alcohol, ethyl alcohol and n-propyl alcohol. Isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and the like. These alcohols generally have longer carbon chains,
Reactivity with metal aluminum decreases.

The metal aluminum as a raw material is not particularly limited, but the metal has a purity of 99.99 in which the concentration of impurities such as iron, silicon, copper, and magnesium is 100 ppm or less.
% Or more of aluminum having a high purity is preferable because the purification of the obtained aluminum alkoxide becomes unnecessary. Metal shapes are ingots, pellets,
Any form such as foil, wire, and powder can be used.

In the reaction between the metal aluminum and the alcohol, the ratio of the amounts of these raw materials used is not unconditional depending on the reaction mode such as a batch system or a continuous system or the desired concentration of aluminum alkoxide, but usually [alcohol] / [metal aluminum ] Of about 3 or more, preferably about 4 or more.

The solvent constituting the liquid phase is, in addition to the alcohol as a raw material, inert to metallic aluminum, and can dissolve the alcohol, aluminum alkoxide, gallium, indium, or a compound of these metals as a product. Solvents such as benzene and toluene may be used.

The reaction temperature of the metal aluminum and the alcohol is not particularly limited as long as the reaction proceeds, but from the viewpoint of accelerating the reaction, a reaction under boiling and reflux conditions of the solvent system used is preferable.

Further, if water is present in the system at the start of the reaction, there are disadvantages such as the formation reaction of aluminum alkoxide being hindered and the addition of gallium or indium as a promoter or a compound of these metals being hydrolyzed. Therefore, it is necessary to sufficiently dehydrate metal aluminum and alcohol used in the reaction.

When the target substance, aluminum alkoxide, is previously present in the system and the reaction is carried out,
It is presumed to be a dehydration effect, but exhibits a reaction promoting effect. The amount of these additives is not particularly limited, but may be 1 to 30% by weight, preferably 3 to 20% by weight based on the liquid phase.

Although the mechanism for promoting the reaction of forming gallium or indium or a compound of these metals with aluminum alkoxide in the present invention is not clear, gallium or indium or a compound of these metals existing in the liquid phase is more likely than gallium or indium. It is presumed to promote the elution of strongly ionically positive aluminum into the liquid phase.

[0023]

According to the method of the present invention described in detail above, metal aluminum and alcohol can be reacted in the presence of a specific trace component without using a toxic substance such as mercuric chloride. By this method, the reaction rate between metal aluminum and alcohol can be remarkably improved, and its industrial value is extremely large.

[Examples] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to these examples. In the present invention, the analysis was performed by the following method.

Analysis of gallium and indium in metallic aluminum: More than 1 ppm was analyzed by emission spectroscopy, and less than 1 ppm was analyzed by glow discharge mass spectrometry.

Analysis of gallium and indium in the reaction liquid phase: Analysis was performed by ICP emission spectroscopy.

Example 1 Approximately 70 was placed in a 2-liter separable flask equipped with a reflux condenser.
g of aluminum pellets (size: about 45m in diameter)
mx thickness 16 mm, purity> 99.999%, Ga <
0.1 g, In <0.1 ppm) and 600 g of an isopropyl alcohol solution containing 10% by weight of aluminum isopropoxide (Ga <0.01 ppm,
In <0.01 ppm), and after stirring for 1 hour, gallium isopoloxide was added to the liquid phase in an amount of 3 gallium metal equivalent.
After adding 0 ppm, the temperature was raised and the reaction was carried out for a predetermined time under boiling reflux of isopropyl alcohol (82 ° C.). With the progress of the reaction, generation of hydrogen gas and dissolution of aluminum were observed. After the reaction for a certain time, the temperature was lowered to take out the aluminum metal, and the weight loss before and after the reaction was examined. Table 1 shows the results.

Examples 2 to 4, Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that the amount of gallium isopropoxide added to the reaction liquid phase was changed as shown in Table 1. Table 1 shows the weight loss of aluminum metal after a predetermined time.
Shown in

Example 5 An aluminum pellet containing about 5 g of gallium and containing about 70 g of aluminum (size: about 4 mm in diameter) was prepared in the same apparatus as in Example 1.
5mm x 16mm thickness, Ga5ppm, In <0.1p
pm) and 600 g of an isopropyl alcohol solution containing 10% by weight of aluminum isopropoxide dissolved therein
(Ga <0.01 ppm, In <0.01 ppm), and the reaction was carried out for a predetermined time under boiling reflux of isopropyl alcohol. After the reaction for a certain period of time, the temperature was lowered to take out the aluminum metal, and the weight loss before and after the reaction was examined.
Table 1 shows the results of analysis of the concentrations of gallium and indium in the solution after the reaction.

Examples 6 and 7 The same reaction as in Example 5 was carried out except that the contents of gallium and indium in metallic aluminum were changed as shown in Table 1. Table 1 shows the results.

Example 8 A reaction was carried out in the same manner as in Example 1 except that indium isopropoxide was added in an amount of 0.5 ppm in terms of indium metal instead of adding gallium isopropoxide to the reaction liquid phase. Table 1 shows the weight loss of the aluminum metal after a predetermined time.

[0032]

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hideko Kadokura 5-1 Sokai-cho, Niihama-shi, Ehime Sumitomo Chemical Industries, Ltd. (56) References JP-A-62-286938 (JP, A) (58) ) Field surveyed (Int. Cl. ⁷ , DB name) C07C 31/32 C07C 29/70

Claims (3)

(57) [Claims] 1. A method for producing aluminum alkoxide by a solid-liquid reaction between metal aluminum and an alcohol, wherein at least one compound of gallium or indium is used in an amount of 0.02 to 50 ppm (in terms of metal) based on a liquid phase.
A method for producing aluminum alkoxide, which comprises causing a solid-liquid reaction between metallic aluminum and alcohol. 2. The process for producing aluminum alkoxide according to claim 1, wherein a solid-liquid reaction between the metal aluminum and the alcohol is carried out by using metal aluminum containing at least one of gallium and indium in an amount of 5 ppm or less in advance. Method. 3. The method for producing aluminum alkoxide according to claim 1, wherein the alcohol is a monohydric alcohol having 1 to 8 carbon atoms.