Method for reducing organotin compound

Abstract

To provide a method for removing an organotin compound that can reduce the organotin compound with high industrial efficiency and down to sub-ppb levels.SOLUTION: A method for reducing an organotin compound comprises a step of bringing a halogenated organotin compound into contact with a solid having a thiol group under basic conditions in an organic solvent, thereby reducing the organotin compound in the organic solvent solution. The method further comprises a step of bringing the organotin compound into contact with a hydrohalic acid to halogenate the organotin compound.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for decomposing an organotin compound to reduce the amount of the organotin compound.

Background Art

[0002] Among the organic compounds synthesized by organic synthesis, many are used as electronic materials and pharmaceutical raw materials. In these applications, strict control of the impurity content is required. For example, the content of metal impurities in electronic materials and pharmaceutical raw materials is required to be at the ppb level on a mass basis, and particularly for organic compounds used in the most advanced semiconductor manufacturing, the content is required to be at the sub-ppb level on a mass basis.

[0003] In the synthesis of organic compounds, reactions using organometallic compounds necessary for obtaining the target compound are widely used. However, in the reactions using the above organometallic compounds, trace metal impurities are often contained in the metals used, and these metal impurities are contained in the produced organic compounds.

[0004] Generally, the metal impurities that are commonly mixed in include sodium, magnesium, potassium, calcium, iron, zinc, nickel, copper, and the like.

[0005] If the metal remaining as an impurity is ionic, the amount of impurities can be reduced from the target product by conventional cleaning methods such as acid cleaning, removal by an ion exchange resin, and removal by a chelating resin.

[0006] On the other hand, if the metal remaining as an impurity is non-ionic such as tin, lead, or arsenic, the metal impurities may be contained in the form of a compound during the reaction process, and it is difficult to remove them from the target product by the above methods. Among them, when the impurity is an organotin compound, it is difficult to decompose because the bond energy between the organic substituent and tin is large, and it is particularly difficult to remove by liquid separation or by an ion exchange resin because it is not ionic.

[0007] As a method for reducing the concentration of an organotin compound as an example of such impurities, for example, a method of reducing it to the order of ppb by acting iron oxide or the like has been proposed (see Patent Document 1). According to the method described in Patent Document 1, it is possible to reduce it to the order of several ppb on a mass basis of tin atoms.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Non-Patent Documents

[0009]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, with the method described in Patent Document 1 above, it is difficult to reduce to an even higher purity required by the market, that is, to a level of sub-ppb on a mass basis.

[0011] Therefore, an object of the present invention is to provide a method for removing an organotin compound that can industrially and efficiently reduce the organotin compound to sub-ppb.

Means for Solving the Problems

[0012] As a result of intensive studies on a method for efficiently removing an organotin compound, the present inventors have found that by reacting a halogenated organotin compound with a solid having a thiol group under basic conditions to immobilize the organotin compound on the solid and then filtering the solid, surprisingly, the organotin compound can be reduced to the sub-ppb level on a mass basis, and thus have completed the present invention.

[0013] That is, the present invention is a method for reducing an organotin compound, including a step of contacting a halogenated organotin compound with a solid having a thiol group in an organic solvent under basic conditions to reduce the organotin compound in the organic solvent solution.

[0014] The present invention can preferably adopt the following aspects. 1) The method for obtaining the halogenated organotin compound includes a step of contacting an organotin compound with a halogen acid for halogenation. 2) Before contacting the organic compound with the solid, the method includes a step of contacting the solid with an amine-based base. 3) The solid is a chelating resin. 4) The halogen acid is hydrogen chloride. 5) The organic solvent contains an organosilicon compound as a target product. 6) The organotin compound is 1 ppb or more and 1000 ppm or less in terms of mass.

Advantages of the Invention

[0015] According to the method of the present invention, an organotin compound can be reduced to the sub-ppb level on a mass basis. Although the reason why the organotin compound can be highly reduced by the method of the present invention is not clear in detail, the inventors presume as follows. That is, for a halogenated organotin compound, since a thiol group has high reactivity under basic conditions, it is considered that tin is thiolated by nucleophilic substitution of the halogen in the halogenated organotin compound (see Non-Patent Document 1).

[0016] It is speculated that by utilizing the above reaction to react a halogenated organotin compound with a solid material having a thiol group, the organotin compound can be immobilized on the solid material, and then the organotin compound can be removed from the system together with the solid material.

[0017] The method for reducing organotin compounds of the present invention is an industrially simple method in which halogenated organotin compounds are immobilized on a solid material having a thiol group under basic conditions and the solid material is filtered to reduce the compounds, making it possible to reduce organotin compounds from a system and highly industrially applicable and versatile. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The method for reducing organotin compounds of the present invention is characterized in that the halogenated organotin compounds are immobilized on a solid material having a thiol group and the solid material is filtered to reduce the organotin compounds. The method for reducing organic compounds according to one embodiment of the present invention will be described in detail below.

[0019] (Organotin compounds) An organotin compound is a compound having tin and an organic substituent such as a hydrocarbon bonded to the tin. The organotin compound to which the method according to the present embodiment can be applied is not limited to a compound having a specific structure, and includes a wide range of compounds, such as alkyltin compounds having a substituent (e.g., trialkyltin compounds, tetraalkyltin compounds, etc.), aryltin compounds, etc. Among them, saturated alkyl compounds are stable compounds and are difficult to decompose, so that the effect of the present invention is more pronounced when applied to such stable compounds.

[0020] (Halogenated organotin compounds) A halogenated organotin compound is a compound in which one or more organic substituents bonded to a tin atom in the above-mentioned organotin compound are replaced by halogen atoms. Here, the halogen atom is a chlorine atom, a bromine atom, or an iodine atom, preferably a chlorine atom or a bromine atom, and more preferably a chlorine atom.

[0021] The method for halogenating an organotin compound is not particularly limited, and known methods such as adding a simple halogen to the organotin compound or adding a halogenating agent may be used.

[0022] In this embodiment, the organotin compound is halogenated by bringing the above-mentioned organotin compound into contact with a hydrohalic acid in an organic solvent. As the hydrohalic acid, for example, hydrochloric acid, hydrobromic acid, etc. may be used. In addition, the hydrohalic acid by-produced when synthesizing the target organic compound may also be used. According to the method of bringing the above-mentioned organotin compound into contact with the hydrohalic acid in an organic solvent, it is preferable in that the influence on the reaction substrate can be reduced more.

[0023] (organic solvent) The above-mentioned organic solvent is not particularly limited, and for example, halomethanes such as dichloromethane, ethers such as tetrahydrofuran, and esters such as propylene glycol monomethyl ether acetate may be used. The above-mentioned halogenation reaction proceeds even in water, but an organic solvent is used in consideration of the subsequent reaction with the thiol resin.

[0024] The temperature when stirring the organic compound containing the organotin compound and the hydrohalic acid is not particularly limited, and it may be appropriately set at a temperature at which the organic compound and the organic solvent are stable, for example, it may be appropriately set in the range of 0 to 30°C. Also, the stirring time is not particularly limited, but for example, it may be 1 hour or more and 30 hours or less.

[0025] From the perspective of improving the removal efficiency of removing organotin compounds in the purification method of this embodiment, the organotin compound is preferably 1 ppb or more and 1000 ppm or less in terms of mass conversion, more preferably 10 ppb or more and 100 ppm or less, and particularly preferably 10 ppb or more and 1 ppm or less. The method according to the present invention is characterized in that it can reduce the organotin compound to a lower level in terms of mass standard, and when the concentration of the organotin compound is low, the effects of the present invention are more significantly manifested. The concentration of the organotin compound can be analyzed, for example, by methods such as ICP-OES and ICP-MS.

[0026] As a case where an organotin compound is contained in the system, there is a case where it is produced using an organometallic compound such as an organomagnesium compound (generally known as a Grignard reagent), an organocopper lithium compound, an organozinc compound, an organo rare earth compound, or an organolead compound. In particular, when an organometallic compound is produced using a simple metal and this organometallic compound is used in the production of an organic compound, tin tends to be contained as an impurity in the simple metal, and it is presumed that the organic compound contains an organotin compound in which tin is bonded to the organic compound by the reaction. The method of the present invention can also be suitably used for the organic compound produced by producing the above organometallic compound.

[0027] Also, it is possible to purify an organosilicon compound having a carbon-silicon bond as an organic compound using the method of this embodiment. A carbosilane compound, which is a kind of organosilicon compound, can be synthesized using a Grignard reagent. However, as described above, since an organotin compound is likely to be mixed as an impurity in the production process, it is preferable to use the purification method of this embodiment. Other examples of the organic compound include tertiary alcohols.

[0028] (Solid matter) A halogenated organotin compound (hereinafter also referred to as "organohalogenated tin compound") is brought into contact with a solid having a thiol functional group (hereinafter also referred to as "thiol group"). By bringing the organohalogenated tin compound into contact with the solid, the organohalogenated tin compound is reacted with the solid having a thiol functional group, and the organotin compound is immobilized on the solid surface and can be purified from the system. In the present embodiment, the solid is a porous, porous type having a thiol group on the inner pore surface of the beads.

[0029] Specifically, the solid is not particularly limited as long as it can be easily separated from a solution (the above-mentioned organic solvent when using an organic solvent), such as small particulate matter such as a film or a chelating resin. A chelating resin having a thiol group is preferable in terms of increasing the contact area with the solution and being easily separated from the system by filtration after use. Hereinafter, the chelating resin having a thiol group is also referred to as "thiol resin".

[0030] The contact between the above-mentioned organohalogenated tin compound and the thiol resin is carried out under basic conditions in order to enhance the reactivity between the thiol resin and the organohalogenated tin compound. The base is not particularly limited and may be appropriately determined in consideration of its reactivity with the organotin compound. An amine compound is preferable in that it can be easily removed from the system because it can be volatilized and purified after treatment with a solution.

[0031] As the amine compound, for example, alkylamine, heterocyclic amine, and heterocyclic aromatic amine can be used. As the alkylamine, for example, trimethylamine and triethylamine can be preferably used. Since the amine compound itself can be a target for removal later, it is preferably one that can be easily removed from the system. Specifically, it is preferable to use one having a relatively low boiling point.

[0032] The solvent used in the reaction of the above-mentioned organic compound with the solid having a thiol functional group is not particularly limited, and organic solvents such as halogenated methanes such as dichloromethane, ethers such as tetrahydrofuran, and esters such as propylene glycol monomethyl ether acetate may be used. Also, the organic solvent may be appropriately determined in consideration of its reactivity and solubility with the organotin compound. Note that the solvent used in the reaction of the organic compound with the solid may be the same as or different from the solvent used in the reaction of the organic compound with the halogen acid.

[0033] The temperature during the reaction with the solid having a thiol functional group is not particularly limited and may be appropriately set at a temperature at which the organic compound and the organic solvent are stable, usually appropriately set in the range of 0 to 30°C.

[0034] When the solid having a thiol functional group is a chelating resin, both batch treatment and column treatment can be applied. In batch treatment, 1 to 30% by mass of the chelating resin is added to the target solution, and after stirring and shaking for 0.5 to 48 hours at a liquid temperature of 0 to 30°C, the chelating resin is purified by filtration to obtain a solution with reduced tin components.

[0035] In column treatment, specifically, after filling a columnar container such as PTFE, PFA, or glass with a chelating resin using an organic solvent in which the target compound is dissolved, the target compound solution is passed through at a space velocity of 1 to 50 h -1 at a liquid temperature of 0 to 30°C to obtain an organic compound solution with reduced tin components.

[0036] (Subsequent treatment) By carrying out the method of the present invention, it is possible to further reduce the organotin compound, and it is also possible to reduce it to the sub-ppb level on a mass basis. Therefore, the organic compound obtained by producing an organic compound using the method of the present invention has high purity and can be used for applications such as electronic materials and pharmaceutical raw materials. When improving the chemical purity of an organic compound, it is also possible to improve the purity by performing known purification operations such as recrystallization and column chromatography. When the organotin compound is incorporated into the organosilicon compound, after removing the organotin compound using the method of the present invention, polycondensation is carried out by a known method to produce an organosilicon compound with a highly reduced organotin compound.

Examples

[0037] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples in any way.

[0038] In the following examples, the purification rate of tin in the organic compound was measured by ICP-MS by the following method.

[0039] (Method for measuring tin) 1 mL of an organic solvent solution in which an organotin compound was dissolved was added to a container made of Teflon (registered trademark), heated on a hot plate to remove the organic solvent. 0.2 mL of ultrapure water and 0.2 mL of nitric acid were added to the residue, and finally 19.6 mL of ultrapure water was added to prepare a sample solution, and the lead concentration was quantified by ICP-MS (ICP-MS7900 manufactured by Agilent Technologies), and the tin concentration was calculated.

[0040] (Example 1-1) Tetrabutyltin, an organotin compound, was dissolved in a tetrahydrofuran solution, 4 mol / L hydrochloric acid was added, and the mixture was stirred for 15 hours. After purifying the tetrahydrofuran solution with an evaporator, it was analyzed by NMR, and the decomposition of tetrabutyltin and the formation of tributyltin chloride were confirmed.

[0041] (Example 1-2) 3.88 g of a solution of tributyltin chloride in propylene glycol monomethyl ether acetate (4.4 ppb) was mixed with 0.22 g of triethylamine and 1.00 g of Kiresparl CH400 (Kiresu Chemical) to prepare a solution. When the concentration of metallic tin in the solution before this treatment was calculated, it was 4.2 ppb. After stirring this solution at room temperature for 15 hours, the chelating resin was filtered, and the tin concentration of the filtrate was measured by ICP-MS and found to be 0.7 ppb.

Claims

1. A process for reducing an organotin compound in an organic solvent solution, the process comprising contacting a halogenated organotin compound with a solid having a thiol group under basic conditions in an organic solvent. A method for reducing an organotin compound.

2. A process for halogenating an organotin compound by contacting the organotin compound with a hydrohalic acid. The method according to claim 1.

3. Before contacting the organic compound with the solid, contacting the solid with an amine-based base. The method according to claim 1 or 2.

4. The solid is a chelating resin. The method according to claim 1 or 2.

5. The hydrohalic acid contains hydrogen chloride. The method according to claim 2.

6. The organic solvent contains an organosilicon compound as a target product. The method according to claim 1 or 2.

7. The organotin compound is from 1 ppb to 1000 ppm in terms of mass. The method according to claim 1 or 2.