JPS626694B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing rare earth metal alkoxides. More specifically, the present invention is based on the general formula () MnX ₃ () [where M is a rare earth metal element (excluding yttrium), that is, scandium (Sc), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), disprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm) , Ytterbium (Yb), Lutetium (Lu), X represents a carboxylic acid residue,
n represents 1 or 2. However, when n represents 1, X represents a monovalent carboxylic acid residue, and when n represents 2, X represents a divalent carboxylic acid residue. ] is reacted with an alkali metal alkoxide represented by the general formula () ROM' () (wherein R represents an alkyl group and M' represents an alkali metal atom). The present invention relates to a method for producing rare earth metal alkoxides having the general formula () M(OR) ₃ , where M and R are as defined above. In recent years, with the progress of the electronics industry, rare earth elements have been used in a wide range of fields, and oxides of rare earth metals play an important role in the field of fine ceramics. In particular, yttrium oxide is attracting a lot of attention because it controls the phase transition of zirconia ceramic products by adding it to zirconia (zirconium oxide). As a method for producing such a rare earth metal oxide, it is useful to add and hydrolyze a rare earth metal alkoxide represented by the general formula (). The conventional method for producing rare earth metal alkoxides, which are intermediates of rare earth metal oxides, is to react scandium chloride anhydride with methanol [Zeitschrift Allorgnischeund,
"Allgemeine Chemie", pp. 67-71, 325 (1-2)
(1963)], a method for reacting anhydrous rare earth metal chlorides with alkali metal alkoxides [Proceeding Nucleus Radiation Chemical,
"Chemistry Symposium" pp. 15-19 (1964), "Chemistry
and Industry”, p. 120 (1963), “Ibid.”, Vol. 9, pp. 382-383 (1965), “Ibid.”, Vol. 32, p. 1379 (1966), “Chemische Berichte”, Vol. 93, pp. 652-383
657 pages (1960), "Inorganic Chemistry" No. 5
(3), pp. 342-346 (1966), “U.S.
3278571], a method of reacting rare earth metals and alcohol using mercuric chloride as a catalyst [``Inorganic Chemistry'' Vol. 5 (3) No. 342
~346 pages (1966), “U.S. Patent No. 3278571”]
was known. A summary comparison of these using chemical formulas is as follows.

【table】

[Table] Method of publication]
However, the conventional method described above not only has a low yield of rare earth metal alkoxide but also has the disadvantage that it contains impurities. As a result, the rare earth metal oxide obtained by hydrolyzing this also contains a large amount of impurities and requires a purification operation to obtain a highly pure rare earth metal alkoxide. As a result, the manufacturing cost of rare earth metal alkoxides becomes high, and rare earth metal oxides cannot be obtained at low cost. Furthermore, among the conventional methods mentioned above, the anhydrous rare earth metal chloride that is the starting material is generally very hygroscopic and is extremely difficult to handle industrially in large quantities; Certain rare earth metals are generally very expensive and require long heating and refluxing to complete the reaction, making them unsuitable for industrial mass production. In view of these circumstances, the present inventors have conducted extensive studies on the method for producing rare earth metal alkoxides. As a result, in contrast to the prior art, a rare earth metal alkoxide can be produced by using a rare earth metal carboxylate anhydride as a starting material instead of a rare earth metal chloride anhydride and reacting this with an alkali metal alkoxide. The present inventors have discovered that this can be obtained in high yield and purity, and have completed the present invention. According to the present invention, rare earth metal alkoxides can be obtained with high purity and high yield, and rare earth metal alkoxides can be produced at low cost without requiring purification operations of rare earth metal alkoxides. That is, in the production method of the present invention, rare earth metal alkoxides can be obtained with almost no impurities and at a high yield of 90% or more. Therefore, the present invention is significantly improved in terms of yield, purity, operability, and economical efficiency compared to the conventional technology, which contained a large amount of impurities and could not obtain the desired product in a low yield. has been done. The method for producing rare earth metal alkoxide of the present invention will be explained in more detail as follows. First, an alkali metal alkoxide is added to a mixed solution of a rare earth metal carboxylate anhydride and an organic solvent, and the mixture is stirred for 1 to 3 hours at a temperature ranging from room temperature to the reflux temperature of the solvent. Thereafter, the reaction solution is filtered to remove the alkali metal carboxylate, resulting in a homogeneous and transparent solution of the rare earth metal alkoxide in an organic solvent. If necessary, this filtrate is evaporated to dryness, and then an organic solvent for dissolution is added to the residue to dissolve the rare earth metal alkoxide, and if any insoluble matter is present, it is filtered to obtain a homogeneous and transparent solution of the rare earth metal alkoxide. The starting material for the reaction, rare earth metal carboxylate anhydride, is 1
Anhydrous or divalent carboxylic acid salts are used, with preference given to the use of formates, acetates, propionates. Also, for 1 mole of rare earth metal carboxylate anhydride, 3 to 3 alkali metal alkoxides
3.3 mol and the organic solvent is preferably in the range of 0.85 to 5 liters from an economic standpoint. In addition, as the reaction solvent used, any inert organic solvent may be used.
From the viewpoint of operability, aromatic hydrocarbons such as benzene, toluene, and xylene, and alcohols such as methanol, ethanol, hexanol, and octanol are preferred. The solvent for dissolving the generated rare earth metal alkoxide may be any solvent as long as it is soluble in the rare earth metal alkoxide, and aromatic hydrocarbons such as benzene, toluene, and xylene are particularly preferable. 0.5 to 5 liters per mole of carboxylic acid anhydride
amount is enough to dissolve the generated rare earth metal alkoxide. Rare earth metal alkoxides are easily hydrolyzed even with trace amounts of moisture, so they are usually used as solutions for the next purpose, but if necessary, they can be easily processed by distilling off the solvent, blocking moisture, and handling carefully. It is also possible to separate them. In the production method of the present invention, the method of reacting the rare earth metal carboxylate anhydride with the alkali metal alkoxide is as shown in (1) below. Alkoxides may be reacted, but (2)
As shown in , an alkali metal may be added to an alcoholic solution of a rare earth metal carboxylate anhydride to generate an alkali metal alkoxide, and this may be reacted with the rare earth metal carboxylate anhydride. The outline is shown below. (1)

[Table] (M, M', R, Add.
Here, solv ₁ and solv ₂ may each independently be an aromatic hydrocarbon such as benzene, toluene, or xylene, or an aliphatic alcohol such as methanol, ethanol, butanol, or octanol, or may be the same. (2) MnX ₃ /solv (alcohol) + alkali metal→
nM(OR) ₃ (M, R, X and n have the same meanings as above) An alkali metal is added to an alcoholic solution of rare earth metal carboxylate anhydride. here solv
For example, an aliphatic alcohol such as methanol, ethanol, butanol, or octanol, or a mixed solvent of these aliphatic alcohols and an aromatic hydrocarbon such as benzene, toluene, or xylene can be used. Next, examples of the present invention will be shown. Example 1 Production of itterbium methoxide [Reaction method (1)] 9.2 g (0.03 mol) of itterbium acetate anhydride and 50 ml of toluene were placed in a 100 ml round bottom flask, and a methanol solution of sodium methoxide was added while stirring. (28% as CH ₃ ONa, 0.09 mol) was added dropwise, and after the dropwise addition, the mixture was heated with a mantle heater and refluxed for 2 hours. After cooling the reaction solution to room temperature and filtering out the precipitated crystals, the filtrate was evaporated to dryness, 30 ml of toluene was added to the residue, the residue was dissolved, and the mixture was filtered.
A homogeneous and transparent toluene solution is obtained. This toluene solution was evaporated to dryness to produce itterbium methoxide.
7.3g (yield 91.9%) was obtained. Elemental analysis values C 13.5% (theoretical value 13.5%) H 3.7% (〃 3.4%) O 18.8% (〃 18.0%) Next, an example using the reaction method (1) of the present invention based on Example 1 was conducted. It is shown in Table 1.

【table】

[Table] Example 16 Production of scandium ethoxide [Method of reaction method (2)] Scandium propionate (0.03 mol), benzene 50 ml and ethanol 10 ml were placed in a 100 ml round bottom flask, and while stirring, 0.6 g of metallic lithium was added.
(0.09 mol) was added gradually. After the addition was completed, the mixture was heated with a mantle heater and refluxed for 1 hour, and then the same procedure as in Example 1 was carried out to obtain 6.4 g of scandium ethoxide (yield: 95.6%). Elemental analysis value C H O Theoretical value 32.2 6.7 21.4 Analysis value 31.8 6.7 21.1 Next, an example of the reaction method (2) of the present invention based on Example 16 is shown in Table 2.

【table】

[Table] Comparative Example 1 (Example described in "Inorg.Chem.") 24.3 g (0.37 mol) of lithium isopropoxide and 150 ml of isopropyl alcohol were placed in a 300 ml round bottom flask, and while stirring, yttrium was dissolved in 25 ml of tetrahydrofuran. 23.4 g (0.12 mol) of trichloride is added dropwise. After completion of the dropwise addition, the mixture was heated to 45°C using a mantle heater, stirred for 3 hours, and then the reaction solution was evaporated to dryness. Add 150ml of benzene to the residue, filter out insoluble matter, and distill off the benzene to obtain 16.8g of yttrium isopropoxide.
(yield 52.6%). Next, Table 3 shows comparative examples based on Comparative Example 1.

[Table] Comparative Example 17 (Example described in "Z, Anorg.All.Chemic.") 150 ml of methanol and 6.1 g (0.04 mol) of anhydrous scandium chloride are placed in a 300 ml round bottom flask and heated to reflux. 0.12 mol of dry ammonia gas was introduced into this, and after heating under reflux for 1 hour, the bulky crystals were filtered out, and the crystals were thoroughly washed with hot methanol to completely remove the replicated ammonium chloride. Methoxide was obtained. The yield is 3.1g and the yield is 56.3
It was %.

Claims (1)

[Claims] 1 General formula MnX ₃ [wherein M represents a rare earth metal element (excluding yttrium), X represents a carboxylic acid residue, and n represents 1 or 2. However, when n represents 1, X represents a monovalent carboxylic acid residue, and n represents 2
When it represents, X represents a divalent carboxylic acid residue. ]
A rare earth metal carboxylate represented by the general formula M is characterized by reacting an alkali metal alkoxide represented by the general formula ROM' (wherein R represents an alkyl group and M' represents an alkali metal atom). A method for producing a rare earth metal alkoxide represented by (OR) ₃ (wherein M and R are as defined above).