JP3602571B2 - Method for producing monoalkylphosphine - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for producing a monoalkyl phosphine as a raw material when forming a compound semiconductor thin film by a MOCVD (Metal Organic Chemical Vapor Deposition) method or the like.
[0002]
[Prior art]
A group III-V compound semiconductor thin film such as indium-phosphorus is useful as a material for forming electronic devices, optical devices, and the like. As a method for obtaining such a compound semiconductor thin film, there are LPE (Liquid Phase Epitaxy), halide CVD, MBE (Molecular Beam Epitaxy), MOMBE (Metal Organic Molecular Beam Epitaxy), MOCVD and the like. Among these methods, MOCVD and MOMBE do not require maintaining a high vacuum in the crystal growth system, and the group III raw material is an organic metal packed in a bubbler, and the group V raw material is a hydride or organic metal packed in a cylinder. Because of the use of, the exchange of raw materials is easy and the productivity is excellent.
[0003]
In such a method, phosphine (PH ₃ ) has conventionally been used as a phosphorus material. However, phosphine is highly toxic, and there is concern about large-scale handling due to mass production.
Therefore, in recent years, monoalkyl phosphines, particularly tertiary butyl phosphine (TBP) in which the alkyl group is a tertiary butyl group, have low toxicity and use of the same is comparable to those grown using phosphine as a raw material. Since a semiconductor thin film can be obtained, it is attracting attention as a phosphorus source material instead of phosphine.
[0004]
As a method for producing monoalkylphosphine, the following method is known (see Rec. Trav. Chim. 82, (1963) p302).
A. The alkyl halide is reacted with magnesium in an organic solvent to form a Grignard reagent.
I. This Grignard reagent and phosphorus trihalide are reacted in an organic solvent at a molar ratio of 1: 1 to obtain phosphonyl dihalide.
C. The by-product magnesium halide and the organic solvent are removed, and phosphonyl dihalide is isolated and purified.
D. When the phosphonyl dihalide is solid at room temperature, it is dissolved in a suitable organic solvent and reduced with a reducing agent such as lithium aluminum hydride to obtain a monoalkylphosphine.
E. The synthesized monoalkylphosphine is purified by distillation.
[0005]
[Problems to be solved by the invention]
When monoalkylphosphine is produced by such a method, generally, dihalogenous phosphonyl has a high boiling point, and monoalkylphosphine has a low boiling point, so that an alkyl halide is reacted with magnesium in an organic solvent. The organic solvent used in the step of preparing a Grignard reagent and reacting this Grignard reagent with phosphorus trihalide in a molar ratio of 1 to 1 in an organic solvent to obtain phosphonyl dihalide should have a low boiling point. The by-product magnesium halide and the organic solvent are removed, and the phosphonyl dihalide is easily purified in the step of isolating and purifying it.On the other hand, when the phosphonyl dihalide is a solid at room temperature, it is converted to an appropriate organic solvent. Is dissolved and reduced with a reducing agent, for example, lithium aluminum hydride, to give the monoalkylphosphine. That the organic solvent used in step is easily purified in the process towards those of the high-boiling purified by distillation monoalkyl phosphine synthesized.
[0006]
Therefore, when producing a monoalkylphosphine by such a procedure, at least two kinds of solvents have been used. The low-boiling organic solvents used here include diethyl ether and tetrahydrofuran from the viewpoint of the solubility of the Grignard reagent, and the high-boiling organic solvents include diethylene glycol dimethyl ether (diglyme) from the viewpoint of the solubility of lithium aluminum hydride. n-butyl ether and the like.
[0007]
However, these organic solvents can be completely removed in the step of removing by-product magnesium halide and the organic solvent, isolating and purifying phosphonyl dihalide, and the step of purifying the synthesized monoalkylphosphine by distillation. If not, it is mixed with a product, monoalkylphosphine, and if this is used as a raw material to produce a compound semiconductor, its properties are degraded. In addition, repeating the steps of isolating and purifying phosphonyl dihalide and the step of purifying the synthesized monoalkylphosphine by distillation has a problem in that the yield is lowered and the productivity is lowered, thereby increasing the cost. .
[0008]
The inventor of the present invention synthesizes phosphonyl dihalide by a Grignard reaction in an organic solvent, and purifies the phosphonyl dihalide in a method of synthesizing monoalkyl phosphine by reducing the phosphonyl dihalide. The reduction reaction is carried out as it is, and the organic solvent used at that time is a solvent that can be separated from the monoalkylphosphine by washing with water, for example, tetrahydrofuran having infinite solubility in water, and a by-product halide and an organic solvent. The tetrahydrofuran and the like are separated into an aqueous phase and an organic phase by washing with water, and the aqueous phase is phase-separated.These steps are repeated to gradually remove tetrahydrofuran contained in the organic phase and to isolate and purify the monoalkylphosphine. The yield and productivity can be improved by reducing the cost, and the cost can be reduced. It was found to be able to reduce the compound.
[0009]
The present invention solves the above-mentioned problems in the production of monoalkylphosphine based on this finding, and comprises reacting phosphorus trihalide with a Grignard reagent to synthesize phosphonyl dihalide, When a monoalkyl phosphine is synthesized by reducing phosphonyl with a reducing agent and the monoalkyl phosphine is separated and recovered, the type of organic solvent used can be reduced, and the organic solvent is removed to form phosphonyl dihalide alone. An object of the present invention is to provide a method for producing a monoalkylphosphine which can eliminate the step of separation and purification, improve the yield and productivity, and reduce the cost.
[0010]
Means and Action for Solving the Problems
The present invention uses an organic solvent that can be separated from a monoalkylphosphine by washing with water, synthesizes a Grignard reagent with an alkyl halide and magnesium, and reacts the Grignard reagent with phosphorus trihalide in the organic solvent. Diphosphonyl dihalide, the monohalophosphine formed by reducing the phosphonyl dihalide in the organic solvent without removing the magnesium halide by-produced at this time, and a halogenated by-product and The above object has been achieved by producing a monoalkylphosphine by separating an organic solvent by washing with water and recovering the monoalkylphosphine.
[0011]
The Grignard reagent can be obtained by dropping an alkyl halide onto magnesium in an organic solvent. In this case, the shape of magnesium is desirably a chip shape in order to increase the reaction efficiency. In this reaction, the reaction is started near the boiling point of the organic solvent to be used, and thereafter, the dropping rate is adjusted so as to maintain the liquid temperature by the heat of the reaction. Thus, the prepared Grignard reagent and the phosphorus trihalide are reacted at a molar ratio of 1: 1.
[0012]
Here, examples of the organic solvent used in the above reaction include diethyl ether and tetrahydrofuran, and it is preferable to use tetrahydrofuran in view of the solubility of by-product magnesium halide and the ease of removal by washing with water. . The product obtained here contains a target substance, phosphonyl dihalide, an organic solvent, and a by-product magnesium halide. Most of the magnesium halide becomes a precipitate in accordance with the solubility, but can be dissolved by adding about 1 liter of an organic solvent to 1 mol thereof, so that the solution is subjected to the next reduction reaction.
[0013]
The reduction reaction is carried out by dropping the obtained phosphonyl dihalide to a solution obtained by dissolving a reducing agent such as lithium aluminum hydride in an organic solvent, so that the intended monoalkylphosphine can be obtained. . This reduction is preferably performed using a reducing agent in an amount equivalent to or more than the phosphonyl dihalide from the viewpoint of the reaction rate. In this case, diglyme and tetrahydrofuran as organic solvents have solubility in the reducing agent, and they are preferable because the solubility of water is infinite. However, tetrahydrofuran can reduce the cost in terms of price. The reaction is preferably performed at a temperature in the range of -10 ° C to 10 ° C in order to prevent runaway of the reaction.
[0014]
The reaction gives a monoalkylphosphine, which contains halides and organic solvents as impurities. Then, dilute sulfuric acid, preferably 1 to 5 N aqueous sulfuric acid, is gradually added to decompose excess lithium aluminum hydride, and then the sulfuric acid aqueous solution is added in such an amount that halide precipitates can be dissolved. The aqueous phase is separated into an organic phase containing an organic solvent such as phosphine and tetrahydrofuran, and an aqueous phase containing sulfuric acid, a halide and an organic solvent, and the aqueous phase is separated. An aqueous solution of sulfuric acid is added again to the remaining organic phase to such an extent that the aqueous solution is split into two phases, and the aqueous phase is removed. Thereafter, the same operation is repeated to obtain a monoalkylphosphine containing no halide and no organic impurities. The organic impurities are tertiary butyl chloride as a raw material (which is decomposed by water to form tertiary butanol, which also shifts to an aqueous phase due to infinite solubility of water) and organic solvents. Are removed by washing with water. The amount of the aqueous sulfuric acid solution added here is preferably the minimum amount required for separation into two phases in order to increase the yield.
[0015]
Since the monoalkylphosphine obtained as described above is free of organic impurities by washing with water, it can be made highly pure by simple distillation.
[0016]
【Example】
Hereinafter, examples of the present invention will be described. All operations in the examples were performed under an inert atmosphere.
(Example 1)
A. 264 ml (2.4 mol) of tert-butyl chloride and 1200 ml of tetrahydrofuran were added dropwise to 57.6 g (2.4 mol) of synthetic magnesium of a Grignard reagent. After the completion of the dropping, the supernatant was transferred to a dropping tube to obtain 1350 ml of a black liquid. The measured titer was 1.42 mol / l, and the yield was 80%.
[0017]
B. Synthesis of tert-butyldichlorophosphine To 261 g (1.91 mol) of phosphorus trichloride, 2000 ml of tetravidrofuran was added, and 1350 ml (1.91 mol) of a tetrahydrofuran solution of a Grignard reagent was prepared. The solution was added dropwise while cooling from C to 10 ° C. After completion of the dropwise addition, the liquid temperature was returned to room temperature, and 2400 ml of tetravidrofuran was added to dissolve the precipitated magnesium chloride. This was analyzed by gas chromatography, and it was confirmed that tert-butyldichlorophosphine had been synthesized.
[0018]
C. Synthesis of mono-tert-butylphosphine To a liquid obtained by adding 2,000 ml of tetravidrofuran to 73 g (1.91 mol) of lithium aluminum hydride was added a solution of the synthesized tert-butyldichlorophosphine at a reaction vessel temperature of -10 ° C to -10 ° C. The solution was added dropwise while cooling so as to be within the temperature range of C.
[0019]
D. Separation of mono-tert-butylphosphine by washing with water 1000 ml of a 3N aqueous sulfuric acid solution was added to the solution obtained above with stirring to dissolve the chloride, and then the stirring was stopped and the mixture was allowed to stand. After the phases were completely separated, the upper organic phase was extracted and analyzed by GC-FID. It contained 22.2% mono-tert-butylphosphine and 75.4% tetrahydrofuran. The operation of further adding 100 ml of an aqueous sulfuric acid solution and extracting the aqueous phase was repeated 30 times, and the obtained organic phase was extracted and analyzed by GC-FID. As a result, tetravidrofuran was not detected, and monotert-butylphosphine was detected. Was 98% or more. The obtained amount was 63 g, and the yield thus far was 29%.
[0020]
E. FIG. Purification by distillation of mono-tert-butylphosphine Mono-tert-butylphosphine obtained by washing with water was considered to have partially decomposed into phosphorus, and was colored yellow, so when purified by distillation, 58 g of a colorless and transparent liquid was obtained. was gotten. The overall yield was 27%. When this was analyzed by GC-FID, peaks of tertiary butanol, tertiary butyl chloride, and tetrahydrofuran, which would be problematic when a semiconductor thin film was formed, were not found, and all were below the detection limit.
(Example 2)
A. 220 ml (2 mol) of tert-butyl chloride and 1000 ml of tetrahydrofuran were dropped into 48 g (2 mol) of synthetic magnesium of a Grignard reagent. After completion of the dropping, the supernatant was transferred to a dropping tube and the titer was measured. The yield here was 89%.
[0021]
B. Synthesis of tert-butyldichlorophosphine To 243 g (2.05 mol) of phosphorus trichloride, 1500 ml of tetravidrofuran was added, and the prepared Grignard reagent was added dropwise thereto. After the completion of the dropwise addition, 1800 ml of a tetravidrofuran solution was added to dissolve the precipitated magnesium chloride.
C. Synthesis of mono-tert-butylphosphine To a solution of 45.6 g (1.2 mol) of lithium aluminum hydride and 1000 ml of tetravidrofuran was added dropwise while cooling the synthesized tert-butyldichlorophosphine solution.
[0022]
D. Separation of mono-tert-butylphosphine by washing with water After stirring the solution obtained above, 2,000 ml of a 2N aqueous sulfuric acid solution was added to dissolve the chloride, stirring was stopped, and the mixture was allowed to stand. After the phases were completely separated, the aqueous phase was removed. Next, 1000 ml of a 2N aqueous sulfuric acid solution was added, and the mixture was separated into two phases, and the aqueous phase was removed. Next, phase separation was performed 33 times with 60 ml of 2N sulfuric acid aqueous solution, and phase separation was performed 8 times with 60 ml of ultrapure water. In this case, the stirring time per one time was about 5 minutes. Thereafter, 120 ml of a 4N aqueous sulfuric acid solution was added, and the mixture was stirred for 20 hours, followed by phase separation. Further, 100 ml of ultrapure water was added, the mixture was stirred for 10 minutes, and then phase separation was performed 21 times. When the obtained organic phase was extracted and analyzed by GC-FID, tetravidrofuran was not detected. The obtained amount was 81 g, and the yield thus far was 45%.
[0023]
E. FIG. Purification by distillation of mono-tert-butylphosphine Mono-tert-butylphosphine obtained by washing with water was dried with a dehydrating agent, and purified by distillation to obtain 72 g. The overall yield was 40%. When this was analyzed by GC-FID, the peaks of tertiary butanol, tertiary butyl chloride, and tetrahydrofuran were all below the detection limit.
(Comparative Example 1)
All operations in Comparative Examples were performed under an inert atmosphere.
[0024]
To 168 g (7 mol) of magnesium, 770 ml (7 mol) of tert-butyl chloride and 1800 ml of diethyl ether were added dropwise. After completion of the dropwise addition, the titer was measured, whereby 5.5 mol of tert-butylmagnesium chloride was obtained. The yield here was 78.6%.
1800 ml of diethyl ether was added to 5.5 mol of phosphorus trichloride, and the prepared Grignard reagent was added dropwise while cooling such that the liquid temperature was -40 ° C or lower. After completion of the dropwise addition, the temperature of the solution was returned to room temperature, and magnesium chloride was filtered (magnesium chloride hardly dissolves in diethyl ether). The filtrate was distilled under reduced pressure to obtain 640 g of a white solid. This was dissolved in 160 g of diglyme and analyzed by GC-FID and NMR, and it was confirmed that the obtained product was tert-butyldichlorophosphine. The yield here was 73.1%.
[0025]
1.6 mol of the obtained tert-butyldichlorophosphine was transferred to a dropping tube, and dropped into a liquid in which 36.5 g (0.96 mol, 1.2 equivalents) of lithium aluminum hydride was dissolved in 1000 ml of diglyme. did. After completion of the dropwise addition, vacuum distillation was performed to recover 94 g of a colorless and transparent liquid. This was analyzed by GC-FID and NMR, and it was confirmed that the obtained product was mono-tert-butylphosphine. The yield here was 65.2%.
[0026]
This was subjected to precision distillation to obtain 66 g of monotert-butylphosphine. The yield here was 70.2%. When this was analyzed by GC-FID, several tens ppm of ether, tertiary butyl chloride and diglyme were detected respectively.
In the case of this method, if the distillation with tert-butyldichlorophosphine and mono-tert-butylphosphine is not repeated, the above-mentioned impurities are mixed in the product. The overall yield was 26.3%.
[0027]
【The invention's effect】
As described above, according to the method for producing a monoalkylphosphine of the present invention, phosphorus trihalide is reacted with a Grignard reagent to synthesize phosphonyl dihalide, and the phosphonyl dihalide is reduced with a reducing agent. When reducing and synthesizing a monoalkylphosphine and separating and recovering the monoalkylphosphine, the type of the organic solvent used can be reduced, and the step of removing the organic solvent and isolating and purifying the phosphonyl dihalide is carried out. There is an effect that the cost can be reduced by improving the yield and the productivity by making it unnecessary, and a high-purity product can be obtained.

Claims (2)

Using an organic solvent which can be separated from the monoalkylphosphine by washing with water, a Grignard reagent is synthesized with the alkyl halide and magnesium, and the Grignard reagent and phosphorus trihalide are reacted in the organic solvent to form a dihalogenous dihalide. Phosphonyl, and then reducing the phosphonyl dihalide in the organic solvent without removing the magnesium halide by-produced at this time, washing the resulting monoalkylphosphine, the by-produced halide and the organic solvent with water And recovering the monoalkyl phosphine. The method for producing a monoalkylphosphine according to claim 1, wherein the organic solvent is tetravidrofuran.