JPH09248463A - Production of scandium triflate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high purity scandium triflate not almost containing an element becoming a minus factor as Lewis acid catalyst function from a low purity scandium compd.-containing aq. soln. containing impurities such as iron, aluminum, nickel or tin other than scandium. SOLUTION: After a low purity scandium compd.-containing aq. soln. is adjusted to pH0.5-4.0, oxalic acid (salt) is added to recover scandium oxalate which is, in turn, baked to form scandium oxide. This scandium oxide is dissolved in trifluoromethanesulfonic acid to be reacted to obtain a scandium triflate aq. soln.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing high-purity scandium triflate showing particularly excellent catalytic activity as a Lewis acid catalyst, which is a main factor in precision organic synthesis.

[0002]

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

Metal trifluoromethanesulfonates such as boron, tin, aluminum and lithium and sodium, so-called metal triflates, are also used as catalysts.

However, in the reaction using these Lewis acid catalysts, the Lewis acid reacts with water preferentially over the reaction substrate, so that decomposition or inactivation occurs, and the presence of a small amount of water causes
It causes a decrease in catalytic reaction or a decrease in yield.

Therefore, when using these catalysts,
It was necessary to carry out the production reaction under the condition of no water at all under an inert gas atmosphere of nitrogen, argon, etc., and using a harmful organic solvent specially dehydrated and purified.

[0006] Therefore, in order to produce the metal triflate, it was necessary to carry out under strict anhydrous conditions, and finally, it was necessary to carry out a strict treatment without adhesion water and crystallization water.

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

In addition, the tin triflate obtained here requires complete removal of adhering water and crystallization water in order to prevent hydrolysis, and further storage thereof requires special equipment such as in a desiccator.

On the other hand, scandium triflate exhibits an excellent catalytic activity as a Lewis acid catalyst and can increase the yield of a desired product, and also has a similar catalytic function not only in an organic solvent but also in an aqueous system. However, the presence of metallic elements such as aluminum, iron, tin and nickel in the scandium triflate causes a significant decrease in its catalytic function.

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

[0011]

DISCLOSURE OF THE INVENTION The present invention provides a low-purity scandium compound-containing aqueous solution containing impurities such as iron, aluminum, nickel, tin, etc. in addition to scandium. By containing high-purity scandium triflate containing almost no, it is possible to carry out not only an organic solvent, but also an aqueous reaction, a synthetic reaction which could be performed only in an organic solvent, Moreover, the present invention provides a method for producing high-purity scandium triflate, which has a novel function as a Lewis acid catalyst capable of increasing the yield of a desired product.

[0012]

One of the inventors of the present invention has found that scandium triflate has a very excellent function as a Lewis acid catalyst which is stable not only in an organic solvent but also in an aqueous system in precision organic synthesis. It has been discovered that it can be an excellent catalyst for reactions, Michael reactions, Diels-Alder reactions and the like.

Therefore, the inventors of the present invention efficiently prepare a scandium triflate having an excellent function as a Lewis acid catalyst from a low-purity scandium acid solution containing an element which has a negative factor as a Lewis acid catalyst function. The inventors have found a method for producing high-purity scandium triflate and have reached the present invention.

The low-purity aqueous solution containing 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, but is a typical one. As for the Japanese Patent Application No. 7-326 filed by the present inventors,
281 and Japanese Patent Application No. 7-326228.

That is, in Japanese Patent Application No. 7-326281, Ni-containing oxide ore is used as a raw material for scandium, and in Japanese Patent Application No. 7-326228, tungsten, uranium, tin smelting residue and ferronickel smelting slag are used as raw materials. , Coal ash, red mud, etc. are used.

Then, in order to concentrate 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 leached from the acid, and nickel and cobalt are selectively precipitated and recovered as sulfides.The subsequent solution is concentrated with a precipitating agent such as calcium carbonate, sodium carbonate, or sodium hydroxide. It describes to obtain a precipitate.

As a typical example of the present invention, the thus obtained concentrated precipitate of scandium is dissolved in sulfuric acid, hydrochloric acid, nitric acid or trifluoromethanesulfonic acid to be used as a scandium compound-containing aqueous solution.

However, such a scandium compound-containing aqueous solution contains, in addition to scandium, impurities such as iron, aluminum, tin, nickel, manganese, magnesium, calcium, and silicon, which are simple substances or compounds. It is still of low purity.

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

That is, according to the present invention, (1) step 1-a low-purity aqueous solution containing a scandium compound is adjusted to a pH range of 0.5 to 4.0, and then oxalic acid (salt) is added to scandium oxalate. Step 2-calcining the scandium oxalate to give scandium oxide, and Step 3-dissolving the scandium oxide with trifluoromethanesulfonic acid and reacting the scandium.
A method for producing high-purity scandium triflate, which comprises obtaining an aqueous solution of triflate, (2) Evaporating and removing excess water contained in the aqueous solution of scandium triflate obtained in the above step 3 to obtain solid scandium triflate. A method for producing high-purity scandium triflate, which comprises: (3) The solid scandium-triflate obtained in (2) above.
(3) The method for producing high-purity scandium triflate according to (1) or (2), wherein the triflate is further dried at a high temperature under 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 obtain a scandium-containing acidic aqueous solution, which was used as a low-purity scandium compound-containing aqueous solution, and the operations from the step 1 to the step 2 were sequentially repeated once or twice or more. Then, the method for producing high-purity scandium triflate according to (1), (2), or (3), characterized in that the step 3 is performed.

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 0.5 to 4.0, preferably 1.0 to 2.5, and then oxalic acid (salt) is added to the oxalic acid. Although it is recovered as scandium, at this time, the recovery rate of scandium decreases if PH is less than 0.5, and if it exceeds 4.0, impurities other than scandium are also included.

As oxalic acid (salt), oxalic acid and ammonium oxalate are used, but 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 room 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 to give scandium oxide, and the calcining temperature is preferably 450 to 1000 ° C. 450 ° C
If it is less than the above range, the oxalate salt is not completely decomposed and remains in scandium oxide, which causes inconvenience to the subsequent dissolution treatment. 1
It may be more than 000 ° C, but it is economically inconvenient.

The scandium oxide is dissolved in a trifluoromethanesulfonic acid solution, and the melting temperature is
By carrying out the reaction at the boiling temperature, the equivalent amount of trifluoromethanesulfonic acid used to become scandium triflate is used, and almost all of the scandium oxide is dissolved in about 2 hours.

The reaction between scandium oxide and trifluoromethanesulfonic acid immediately becomes a scandium triflate solution when dissolved.

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

Further, in order to obtain a high-purity scandium triflate aqueous solution, the scandium oxide is dissolved with hydrochloric acid, nitric acid, sulfuric acid or trifluoromethanesulfonic acid to prepare a scandium-containing acidic aqueous solution, and the pH of step 1 is again adjusted. A higher purity scandium triflate aqueous solution is obtained by repeating adjustment, generation of scandium oxalate by an oxalate salt, and formation of scandium oxide by firing in step 2 and then dissolution with trifluoromethanesulfonic acid solution in step 3.

The high-purity aqueous solution of scandium triflate thus obtained contains a considerable amount of excess water, and thus the excess water is removed. The removal method can be carried out by evaporating the aqueous solution at the boiling point temperature.
By vacuum evaporation at about 300 Torr, 60 ℃
Excess water is removed by evaporation at a low temperature, and a solid of scandium triflate is easily obtained.

The scandium triflate solid matter contains some adhered water and an excess of trifluoromethanesulfonic acid remaining at this point. Therefore, if necessary, the scandium triflate solid matter may be dried under vacuum at a 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 less than 160 ° C, the removal of trifluoromethanesulfonic acid becomes insufficient,
Above that, scandium triflate is thermally decomposed, and the function as a catalyst deteriorates.

The scandium triflate solid thus obtained easily adsorbs water in the atmosphere, and therefore, 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 impairing the 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 Ni-containing oxide ore and a tin smelting residue was subjected to sulfuric acid leaching under high temperature and high pressure, and Ni and Sc were selectively acid-leached, and Ni was selectively selected as a sulfide. The scandium hydroxide compound, which is a scandium concentrate obtained by subjecting the precipitate to recovery by precipitation, and then depositing the solution with sodium hydroxide, 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
1 l of water was added to 100 g of scandium hydroxide compound having a: 0.57% and Si: 0.32%, and 35% hydrochloric acid was added at a temperature of 60 ° C. so that the pH was 1.0, and then for 1 hour. After being dissolved, it is 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, a solution of Si: 0.27 g / l was obtained. At this time, the Sc solubility of the scandium hydroxide compound was 98%.

Ammonia water is added to this solution to add PH.
After setting to 1.8, 1.1 times the amount necessary for Sc to produce ammonium oxalate as scandium oxalate, 1.1 times amount was added and reaction aging was carried out at 60 ° C. for 1 hour to obtain scandium oxalate. Obtained.

At this time, the Sc recovery rate is 97.6%, and the coprecipitation rate of impurities other than Sc is Fe: 0.3%, A
1: 0.1%, Sn: 0.1%, Mn: 0.2%, N
It was 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 solution of 15N trifluoromethanesulfonic acid in an amount of 1.05 equivalent of the amount necessary to dissolve scandium oxide as scandium triflate, and the boiling point was 120 ° C. After dissolution for a period of time, 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 vacuum degree of 100 Torr by using an evaporator, and a white solid substance was obtained in about 1 hour. . Further, high-temperature vacuum drying was performed at a temperature of 200 ° C. and a vacuum degree 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 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 consisting of 99.3% as a scandium triflate was obtained.

[0043]

Example 2 A scandium concentrate obtained by similarly acid-leaching Ni and Sc from the mixed raw material used in Example 1 and recovering the liquid after recovering Ni as a sulfide by precipitation with calcium carbonate Was used.

That is, Sc: 2.35%, Fe: 1.
16%, Al: 4.65%, Sn: 0.56%, Mn:
0.32%, Ni: 0.12%, Mg: 0.22%, C
a: 18.3% and Si: 0.25%, 200 g of scandium carbonate compound having 1% of water was added at a temperature of 6
At 0 ° C., the solution was dissolved in sulfuric acid so that the pH became 1.0, and then filtered, 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 having a concentration of 1 g / l was obtained. At this time, the Sc solubility of the scandium carbonate compound was 96%.

To this solution, 1.1 times the amount necessary to produce ammonium oxalate as Sc for scandium oxalate was added, and the reaction solution was aged at 60 ° C. for 1 hour to give scandium oxalate. Got

At this time, the Sc recovery rate is 96.5%, and the deposition rate of impurities other than Sc is Fe: 0.2%, A
1: 0.1%, Sn: 0.1%, Mn: 0.1%, N
i was 0.2% and Mg was 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 trifluoromethanesulfonic acid solution in an amount of 1.05 equivalent of the amount necessary to dissolve scandium oxide as scandium triflate. After dissolution for a period of time, an aqueous scandium triflate solution was obtained.

The thus obtained aqueous solution was subjected to low temperature vacuum evaporation of excess water at a temperature of 60 ° C. and a vacuum degree of 100 Torr by using an evaporator, and a white solid substance was obtained in about 1 hour. . Further, high-temperature vacuum drying was performed at a temperature of 200 ° C. and a vacuum degree 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 Sc: 9.02%, Fe: 92 ppm, Al: 1.
26 ppm, Sn: 18 ppm, Mn: 12 ppm, N
A high-purity scandium triflate containing i: 8 ppm, Ca: 45 ppm, Si: 3 ppm and 99% as a scandium triflate was obtained.

[0051]

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

This low-purity scandium triflate aqueous solution was subjected to the operation for producing scandium oxalate by the oxalate salt, which was carried out directly at the temperature of 60 ° C., by using an evaporator. When low-temperature vacuum evaporation of excess water was performed at a vacuum degree of 100 Torr, a gray solid substance was obtained in about 1 hour. Furthermore, high-temperature vacuum drying was performed at a temperature of 200 ° C. and a vacuum degree of 10 ⁻¹ Torr for 24 hours to obtain a powder of scandium triflate, which was then sealed with argon gas.

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

The composition as scandium triflate was 29.0%.

[0055]

[Comparison of catalytic functions] The catalytic functions of the high-purity scandium triflate obtained in Examples 1 and 2 and the scandium triflate obtained in Comparative Examples and high-purity tin triflate which is a typical metal triflate are compared below. An example is shown. (Aldol reaction) In the presence of a catalyst of 10 mol% based on the reaction product, benzaldehyde is reacted with silyl enol ether derived from cyclohexane for 5 hours at room temperature in water-THF (1: 4) to give a corresponding aldol compound. Get (1).

[0056]

Embedded image

[0057]

[Table 1]

(Mannich reaction) 10 mol% based on the reaction product
In the presence of the catalyst of methylene chloride at −78 ° C., benzaldehyde is reacted with aniline and then ketene silyl acetal derived from methyl isobutyrate, and further reacted at the same temperature for 3 hours to give 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.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Kobayashi 1-6-6-702 Sarugakucho, Chiyoda-ku, Tokyo

Claims (4)

[Claims] 1. Step 1-Adjusting a low-purity aqueous solution containing a scandium compound to a pH range of 0.5 to 4.0, and then adding oxalic acid (salt) to recover as scandium oxalate, and Step 2- The scandium oxalate is calcined to give scandium oxide, and the step 3 is to dissolve the scandium oxide with trifluoromethanesulfonic acid to cause a reaction.
A method for producing high-purity scandium triflate, which comprises obtaining an aqueous triflate solution. 2. The scandium obtained in the step 3
Excess water contained in the aqueous triflate solution is removed by evaporation to obtain solid scandium triflate.
A method for producing high-purity scandium triflate, which comprises: 3. The solid scandium triflate obtained in claim 2 is further dried at high temperature under 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 with an acid to prepare a scandium-containing acidic aqueous solution, which is used as a low-purity scandium compound-containing aqueous solution, and the steps 1 to 2 are performed. The method for producing high-purity scandium triflate according to claim 1, 2 or 3, wherein the step 3 is performed after repeating one or more times in succession.