JP3327110B2 - Method for producing scandium triflate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing high-purity scandium triflate which exhibits particularly excellent catalytic activity, for example, as a Lewis acid catalyst which is a main component of precision organic synthesis.

[0002]

2. Description of the Related Art As Lewis acids used in the field of precision organic synthetic chemistry, metal compounds such as aluminum and titanium, for example, aluminum chloride and titanium chloride are used as catalysts.

Also, metal trifluoromethanesulfonates such as boron, tin, aluminum and lithium and sodium, so-called metal triflates, have been used as catalysts.

However, in the reactions using these Lewis acid catalysts, the Lewis acid reacts with water preferentially over the reaction substrate, and thus decomposes or inactivates.
This leads to a decrease in the catalytic reaction or a decrease in the yield.

Therefore, when these catalysts are used,
The production reaction had to be carried out under an atmosphere of an inert gas such as nitrogen or argon under a completely water-free condition, and using a harmful organic solvent specially dehydrated and purified.

[0006] Therefore, in order to produce a metal triflate, it is necessary to carry out under a strictly anhydrous condition, and finally, it is necessary to carry out a strict treatment without adhering water and crystallization water.

For example, tin triflate, a typical metal triflate, is produced by mixing anhydrous stannous chloride, which has been previously dehydrated and purified, and trifluoromethanesulfonic acid, which has also been previously dehydrated and purified, under strict anhydrous conditions. (T. Mukaiyama, N. Iwasaw
a, R.A. W. Stevens, T .; Haga, Tetr
ahedron, 40, 1381 (1984)).

Further, the tin triflate obtained here needs to completely remove attached water and water of crystallization in order to prevent hydrolysis, and further requires special equipment such as storage in a desiccator.

On the other hand, scandium triflate exhibits excellent catalytic activity as a Lewis acid catalyst, enables a high yield of a desired product, and has a catalytic function not only in an organic solvent but also in an aqueous system. However, when metal elements such as aluminum, iron, tin and nickel are present in scandium triflate, the catalytic function thereof is significantly reduced.

Therefore, it is necessary to minimize the presence of these metallic elements as impurities.

[0011]

DISCLOSURE OF THE INVENTION The present invention relates to a method for producing a Lewis acid catalyst function from a low-purity aqueous solution containing a scandium compound containing impurities such as iron, aluminum, nickel and tin in addition to scandium. By producing a high-purity scandium triflate containing almost no, a synthesis reaction that could only be performed in an organic solvent until now can be performed not only in an organic solvent but also in an aqueous system, In addition, the present invention provides a method for producing high-purity scandium triflate having a novel function as a Lewis acid catalyst capable of increasing the yield of a target product.

[0012]

Means for Solving the Problems One of the present inventors believes that scandium triflate has a very excellent function as a Lewis acid catalyst which is stable not only in organic solvents but also in aqueous systems in precision organic synthesis, It has been found to be an excellent catalyst such as a reaction, a Michael reaction and a Diels-Alder reaction.

Therefore, the present inventors have found that, in synthesizing scandium triflate having an excellent function as a Lewis acid catalyst, a low-purity scandium acid solution containing an element which is a negative factor as a Lewis acid catalyst function can be efficiently produced. The inventors have found a method for producing high-purity scandium triflate, and have reached the present invention.

The low-purity aqueous solution of a scandium compound in the present invention is not particularly limited as long as it is an acidic, neutral or alkaline aqueous solution containing a scandium compound having an impurity component. Japanese Patent Application No. 7-326 filed earlier by the present inventors
281 and Japanese Patent Application No. 7-326282.

That is, in Japanese Patent Application No. 7-326281, a nickel-containing oxide ore is used as a raw material of scandium, and in Japanese Patent Application No. 7-326282, a residue of smelting tungsten, uranium, tin or smelting ferro-nickel is used as a raw material. Use coal ash, red mud, etc.

Then, in order to concentrate and separate and recover scandium contained in a trace amount in these raw materials, these raw materials are subjected to acid leaching under high temperature and high pressure in an oxidizing atmosphere,
Nickel, cobalt and scandium are selectively precipitated and recovered as sulfides from a solution in which nickel, cobalt or scandium is selectively leached. Scandium is concentrated from the subsequent solution using a precipitant such as calcium carbonate, sodium carbonate or sodium hydroxide. It describes obtaining a precipitate.

In the present invention, typically, the scandium concentrated precipitate thus obtained is dissolved in sulfuric acid, hydrochloric acid, nitric acid or trifluoromethanesulfonic acid and used as an aqueous solution containing a scandium compound.

However, such a scandium compound-containing aqueous solution contains, in addition to scandium, a simple substance such as iron, aluminum, tin, nickel, manganese, magnesium, calcium, silicon, or an impurity of a compound. It is still low purity.

An object of the present invention is to produce high-purity scandium triflate by removing these impurities.

That is, the present invention provides: (1) Step 1—After adjusting a low-purity aqueous solution containing a scandium compound to a pH in the range of 0.5 to 4.0, oxalic acid (salt) is added, and scandium oxalate is added. Step 2-firing the scandium oxalate to scandium oxide; and step 3-dissolving the scandium oxide with trifluoromethanesulfonic acid and reacting the same.
A method for producing high-purity scandium triflate, which comprises obtaining an aqueous triflate solution; (2) evaporating and removing excess water contained in the aqueous scandium triflate solution obtained in the step 3 to remove solid scandium triflate; A method for producing high-purity scandium triflate comprising: (3) the solid scandium triflate obtained in (2) above;
The method for producing high-purity scandium triflate according to (1) or (2), wherein the triflate is further dried under high temperature and reduced pressure, and then sealed with an inert gas. (4) In the step 2, The obtained scandium oxide was further dissolved with an acid to form a scandium-containing acidic aqueous solution, and this was used as a low-purity scandium compound-containing aqueous solution, and the operations from Step 1 to Step 2 were sequentially repeated once or twice or more. The method for producing high-purity scandium triflate according to (1), (2) or (3), wherein the method is subjected to the step 3 thereafter.

Hereinafter, the present invention will be described in detail.

The pH of the low-purity aqueous solution containing a scandium compound in the present invention is adjusted to a range of 0.5 to 4.0, preferably 1.0 to 2.5, and oxalic acid (salt) is added thereto to add oxalic acid. At this time, if the PH is less than 0.5, the recovery rate of scandium is reduced. If the pH is more than 4.0, impurities other than scandium are also contained.

As oxalic acid (salt), oxalic acid and ammonium oxalate are used. 1.0 to 1.5 equivalents are added to scandium, and the precipitate is recovered as scandium oxalate.

The temperature at this time may be normal temperature, but by carrying out at a temperature of about 60 to 80 ° C., scandium oxalate having good solid-liquid separation and filterability can be obtained.

The scandium oxalate thus obtained is calcined into scandium oxide, and the calcining temperature is preferably from 450 to 1000 ° C. 450 ° C
If it is less than 10, the oxalate does not completely decompose and remains in the scandium oxide, causing inconvenience in the subsequent dissolution treatment. 1
Although it may be higher than 000 ° C., it is economically inconvenient.

The scandium oxide is dissolved in a trifluoromethanesulfonic acid solution.
By performing the reaction at the boiling point, almost the entire amount of scandium oxide dissolves in about 2 hours with an equivalent amount of trifluoromethanesulfonic acid necessary for forming scandium triflate.

The reaction between scandium oxide and trifluoromethanesulfonic acid immediately turns into a scandium triflate solution upon dissolution.

Since the boiling point temperature can be increased as the concentration of the trifluoromethanesulfonic acid solution increases, an acid concentration of 10 N or more is preferable.

Further, in order to obtain a high-purity aqueous solution of scandium triflate, the scandium oxide is dissolved with hydrochloric acid, nitric acid, sulfuric acid or trifluoromethanesulfonic acid, and the resulting solution is converted into a scandium-containing acidic aqueous solution. After preparing scandium oxalate by oxalate and forming scandium oxide by baking in step 2, dissolving with trifluoromethanesulfonic acid solution in step 3 is repeated to obtain a higher-purity aqueous scandium triflate solution.

Since the high-purity aqueous solution of scandium triflate thus obtained contains a considerable amount of excess water, the excess water is removed. The removal method can be performed by evaporating the aqueous solution at the boiling point temperature.
By performing vacuum evaporation at about 300 Torr,
At a temperature as low as possible, excess water is removed by evaporation, and a solid of scandium triflate is easily obtained.

At this point, some of the scandium triflate solids have some attached water and an excess of trifluoromethanesulfonic acid. In some cases, these are dried by vacuum drying at a higher temperature of about 10 ⁻² torr. Need to be removed.

The temperature at this time is preferably in the range of 160 ° C. to 350 ° C. If the temperature is lower than 160 ° C., the removal of trifluoromethanesulfonic acid becomes insufficient, and
Above this, scandium triflate is thermally decomposed and its function as a catalyst is reduced.

The scandium triflate solid obtained in this manner easily adsorbs moisture in the air atmosphere. In particular, when used in an organic solvent, argon gas,
By sealing and storing with an inert gas such as nitrogen gas, it can be used without deteriorating excellent catalytic activity.

[0034]

The present invention will be described below in more detail with reference to examples.

[0035]

EXAMPLE 1 A mixed raw material of a nickel-containing oxide ore and a tin smelting residue was subjected to sulfuric acid leaching under high temperature and high pressure, and Ni and sulfide were selectively removed from a liquid in which Ni and Sc were selectively leached with acid. Then, a scandium hydroxide compound, which is a scandium concentrate obtained by precipitation of sodium hydroxide from the liquid, was used.

That is, Sc: 8.16%, Fe: 2.
43%, Al: 12.7%, Sn: 1.2%, Mn:
0.47%, Ni: 0.53%, Mg: 1.50%, C
To 100 g of a scandium hydroxide compound having components of a: 0.57% and Si: 0.32%, 1 liter of water was added. The mixture was dissolved after filtration and filtered, Sc: 7.96 g / l,
Fe: 2.33 g / l, Al: 11.7 g / l, Sn:
1.08 g / l, Mn: 0.44 g / l, Ni: 0.5
0 g / l, Mg: 1.43 g / l, Ca: 0.55 g /
1, Si: A solution having a concentration of 0.27 g / l was obtained. At this time, the Sc dissolution rate of the scandium hydroxide compound was 98%.

Ammonia water is added to this solution to adjust the pH.
After that, 1.8 times the amount of ammonium required to produce ammonium oxalate as scandium oxalate was added, and the mixture was allowed to react and mature at 60 ° C. for 1 hour to prepare scandium oxalate. Obtained.

At this time, the Sc recovery rate was 97.6%, and the coprecipitation rate of impurities other than Sc was Fe: 0.3%, A
1: 0.1%, Sn: 0.1%, Mn: 0.2%, N
i: 0.3% and Mg: 0.2%.

Scandium oxalate was calcined at 800 ° C. for 3 hours to obtain scandium oxide.

The scandium oxide thus obtained was added to a 15N solution of trifluoromethanesulfonic acid in an amount of 1.05 equivalents required for dissolving the scandium oxide as scandium triflate. After dissolving for an hour, an aqueous scandium triflate solution was obtained.

The aqueous solution thus obtained was subjected to low-temperature vacuum evaporation of excess water at a temperature of 60 ° C. and a degree of vacuum of 100 Torr by using an evaporator, and a white solid was obtained in about 1 hour. . Furthermore, high-temperature vacuum drying was performed at a temperature of 200 ° C. and a degree of vacuum of 10 ⁻¹ torr for 24 hours to obtain a white powder of scandium triflate, which was then sealed with argon gas.

The composition of the resulting scandium triflate was as follows: Sc: 9.08%, Fe: 78 ppm, Al: 1
32 ppm, Sn: 12 ppm, Mn: 10 ppm, N
i: 17 ppm, Mg: 3 ppm, Ca: 52 ppm,
Si: 3 ppm and high purity scandium triflate of 99.3% as scandium triflate was obtained.

[0043]

Example 2 Scandium concentrate obtained by subjecting the mixed raw material used in Example 1 to acid leaching of Ni and Sc and recovering Ni as a sulfide by precipitation with calcium carbonate A scandium carbonate compound was used.

That is, Sc: 2.35%, Fe: 1.35%
16%, Al: 4.65%, Sn: 0.56%, Mn:
0.32%, Ni: 0.12%, Mg: 0.22%, C
a: 18.3%, Si: 0.25% A scandium carbonate compound having a content of 0.25% was added to 200 g of a scandium carbonate compound, and 1 l of water was added.
At 0 ° C., the mixture was dissolved with sulfuric acid so that the pH became 1.0, followed by filtration. Sc: 4.42 g / l, Fe: 2.16 g /
1, Al: 8.65 g / l, Sn: 1.08 g / l, M
n: 0.60 g / l, Ni: 0.22 g / l, Mg:
0.40 g / l, Ca: 0.46 g / l, Si: 0.3
A solution with a concentration of 1 g / l was obtained. At this time, the Sc dissolution rate of the scandium carbonate compound was 96%.

To this solution was added 1.1 times the equivalent required for Sc to produce scandium oxalate as ammonium oxalate, and the mixture was allowed to react and ripen at 60 ° C. for 1 hour. I got

At this time, the Sc recovery rate was 96.5%, and the precipitation rate of impurities other than Sc was Fe: 0.2%, A
1: 0.1%, Sn: 0.1%, Mn: 0.1%, N
i: 0.2%, Mg: 0.1%.

Scandium oxalate was calcined at 800 ° C. for 3 hours to obtain scandium oxide.

The scandium oxide thus obtained was added to a 15N solution of trifluoromethanesulfonic acid in an amount of 1.05 equivalents required for dissolving the scandium oxide as scandium triflate. After dissolving for an hour, an aqueous scandium triflate solution was obtained.

The aqueous solution thus obtained was subjected to low-temperature vacuum evaporation of excess water at a temperature of 60 ° C. and a degree of vacuum of 100 Torr by using an evaporator. As a result, a white solid was obtained in about 1 hour. . Furthermore, high-temperature vacuum drying was performed at a temperature of 200 ° C. and a degree of vacuum of 10 ⁻¹ torr for 24 hours to obtain a white powder of scandium triflate, which was then sealed with argon gas.

The composition of the obtained scandium triflate was as follows: 9.02% of Sc, 92 ppm of Fe, and 1: 1 of Al
26 ppm, Sn: 18 ppm, Mn: 12 ppm, N
i: 8 ppm, Ca: 45 ppm, Si: 3 ppm, and a high-purity scandium triflate of 99% as scandium triflate was obtained.

[0051]

Comparative Example 1 One liter of water was added to 100 g of the scandium hydroxide compound having the components of Example 1, and the temperature was 60 ° C.
Was dissolved in trifluoromethanesulfonic acid to obtain an aqueous solution of scandium triflate. The liquid PH at that time was 1.5, and the Sc dissolution rate of the scandium hydroxide compound was 98%.

This low-purity aqueous scandium triflate solution was not subjected to the operation of forming scandium oxalate with oxalate as described in Examples, but the aqueous scandium triflate aqueous solution was directly heated to a temperature of 60 ° C. by using an evaporator. When low-temperature vacuum evaporation of excess water was performed at a degree of vacuum of 100 Torr, a gray solid was obtained in about 1 hour. Further, high-temperature vacuum drying was performed at a temperature of 200 ° C. and a degree of vacuum of 10 ⁻¹ torr for 24 hours to obtain scandium triflate powder, which was then sealed with argon gas.

The scandium triflate thus obtained is gray and has a composition of Sc: 2.65.
%, Fe: 0.67%, Al: 3.62%, Sn: 0.
32%, Mn: 0.14%, Ni: 0.16%, Mg:
0.43%, Ca: 0.15%, Si: 0.05%.

The composition as scandium triflate was 29.0%.

[0055]

[Comparison of catalytic functions] Comparison of the catalytic functions of the high-purity scandium triflate obtained in Examples 1 and 2, the scandium triflate obtained in Comparative Example, and the high-purity tin triflate, which is a typical metal triflate, will be described below. An example is shown. (Aldol reaction) Benzaldehyde was reacted with cyclohexane-derived silyl enol ether at room temperature for 5 hours in water-THF (1: 4) in the presence of a catalyst of 10 mol% with respect to the reaction product, and the corresponding aldol derivative was obtained. Obtain (1).

[0056]

Embedded image

[0057]

[Table 1]

(Mannich reaction) 10 mol% based on the reaction product
Aniline and then ketene silyl acetal derived from methyl isobutyrate are reacted with benzaldehyde at −78 ° C. in methylene chloride in the presence of the above catalyst, and further reacted at the same temperature for 3 hours to form the corresponding adduct (2). obtain.

[0059]

Embedded image

[0060]

[Table 2]

[0061]

According to the present invention, scandium triflate having high purity and high catalytic activity can be produced.

Continued on the front page (72) Inventor Hiromasa Yakushiji Aomori Prefecture Hachinohe-shi Ohara Kawagi tree character Toyama Nitta (without address) Taiheiyo Metal Co., Ltd. Hachinohe Works (72) Inventor Osamu Kobayashi 1-Sarugakucho, Chiyoda-ku, Tokyo 6-6-702 (56) References JP-A-9-249672 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07F 5/00

Claims (4)

(57) [Claims] Step 1-After adjusting a low-purity aqueous solution containing a scandium compound to a pH in the range of 0.5 to 4.0, oxalic acid (salt) is added thereto, and the resulting solution is recovered as scandium oxalate. Calcinating the scandium oxalate to scandium oxide; Step 3-dissolving and reacting the scandium oxide with trifluoromethanesulfonic acid to form scandium oxide;
A method for producing high-purity scandium triflate, comprising obtaining an aqueous triflate solution. 2. The scandium obtained in the step 3
Evaporating and removing excess water contained in the aqueous triflate solution to obtain a solid scandium triflate,
A method for producing high-purity scandium triflate comprising: 3. The solid scandium triflate obtained in claim 2 is further dried at high temperature and reduced pressure, and then sealed with an inert gas. A method for producing high-purity scandium triflate. 4. The scandium oxide obtained in the step 2 is further dissolved in an acid to form a scandium-containing acidic aqueous solution, which is used as a low-purity scandium compound-containing aqueous solution. The method for producing high-purity scandium triflate according to claim 1, wherein the method is repeated once or twice or more and then subjected to the step 3.