Method for producing N-alkylborazine compounds

Abstract

To provide a production method capable of obtaining an N-alkylborazine compound in high yield.SOLUTION: There is provided a method for producing an N-alkylborazine compound by reacting an alkali borohydride represented by ABH4 (A is a lithium atom, a sodium atom or a potassium atom) with an alkylamine salt represented by RNH3X (R is an alkyl group, and X is a halogen atom) in an organic solvent. The method is characterized in that the alkali borohydride and the alkylamine salt are reacted while applying a stirring power of 0.1 to 10 kW per 1 m3 of the total volume of the reaction liquid containing the alkali borohydride, the alkylamine salt and the organic solvent.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing an N-alkylborazine compound. [Background technology]

[0002] As information devices become more sophisticated, LSI design rules are becoming finer year by year. In manufacturing LSIs with fine design rules, the materials that make up the LSIs must also be high-performance and function properly on the fine LSIs.

[0003] For example, when it comes to materials used for interlayer insulating films in LSIs, a high dielectric constant causes signal delays. The impact of this signal delay is particularly large in miniaturized LSIs. For this reason, there has been a demand for the development of new low-dielectric materials that can be used as interlayer insulating films. To be used as an interlayer insulating film, materials must not only have a low dielectric constant, but also excel in other properties such as moisture resistance, heat resistance, and mechanical strength.

[0004] In order to meet such demands, a borazine compound having a borazine ring skeleton in the molecule has been proposed, and since the molecular polarizability is small, the formed coating film has a low dielectric constant and is also excellent in heat resistance. As such a borazine compound, there is N-alkylborazine in which the nitrogen atom constituting the borazine ring is bonded to an alkyl group, and it is preferably used to form an interlayer insulating film for semiconductors, a barrier metal layer, and an etch stopper layer.

[0005] For example, Patent Document 1 describes a method for producing N-alkylborazine, which includes a step of charging a reaction vessel with either an alkali borohydride represented by ABH4 (A is a lithium atom, a sodium atom, or a potassium atom) or an alkylamine salt represented by RNH3X (R is an alkyl group and X is a halogen atom) and gradually supplying the other to the reaction vessel and reacting them in a solvent, and discloses a method for producing N-alkylborazine in which the alkali borohydride and the alkylamine salt are gradually supplied to a reaction vessel and reacted with each other in a solvent. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-213683 A Summary of the Invention [Problem to be solved by the invention]

[0007] According to the production method disclosed in Patent Document 1, it is described that the amount of hydrogen gas generated can be controlled in the reaction of an alkali borohydride with an alkylamine salt. However, further studies by the present inventors revealed that in the method of reacting an alkali borohydride with an alkylamine salt in an organic solvent, it may be difficult to efficiently obtain an N-alkylborazine compound in a high yield.

[0008] Therefore, an object of the present invention is to provide a production method capable of obtaining an N-alkylborazine compound in high yield. [Means for solving the problem]

[0009] The present invention which achieves the above object is as follows. [1] A method for producing an N-alkylborazine compound by reacting an alkali borohydride represented by ABH4 (A is a lithium atom, a sodium atom, or a potassium atom) with an alkylamine salt represented by RNH3X (R is an alkyl group, and X is a halogen atom) in an organic solvent, The total volume of the reaction solution containing the alkali borohydride, the alkylamine salt, and the organic solvent is 1 m 3 13. A method for producing an N-alkylborazine compound, comprising reacting the alkali borohydride with the alkylamine salt while applying a stirring power of 0.1 to 10 kW per minute. [2] The method according to [1], comprising reacting the alkali borohydride and the alkylamine salt at 100 to 200°C. [3] The method according to [1] or [2], wherein the alkali borohydride is sodium borohydride (NaBH4). [4] The method according to any one of [1] to [3], wherein the alkylamine salt is monomethylamine hydrochloride (CH3NH3Cl). [5] The method according to any one of [1] to [4], wherein the organic solvent is at least one selected from the group consisting of monoglyme, diglyme, triglyme, and tetraglyme. [6] The method according to any one of [1] to [5], wherein the alkali borohydride and the alkylamine salt are reacted in a reaction vessel having a volume of 0.5 to 10,000 L. [7] The method according to any one of [1] to [6], wherein the reaction solution is stirred using at least one type of stirring blade selected from the group consisting of a propeller type, a paddle type, a turbine type, a cone type, a ribbon screw type, and a Max Blend type. Effect of the Invention

[0010] According to the present invention, an N-alkylborazine compound can be obtained in high yield, and preferably, the amount of a borazane compound, which is a reaction intermediate, in the final product can be reduced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention relates to a method for producing an N-alkylborazine compound by reacting an alkali borohydride represented by ABH4 (A is a lithium atom, a sodium atom, or a potassium atom) with an alkylamine salt represented by RNH3X (R is an alkyl group, and X is a halogen atom) in an organic solvent, the total volume of a reaction solution containing the alkali borohydride, the alkylamine salt, and the organic solvent being 1 m 3 The method is characterized in that the alkali borohydride and the alkylamine salt are reacted with each other by applying a stirring power of 0.1 to 10 kW per unit time. By applying the stirring power to proceed with the reaction, the N-alkylborazine compound can be obtained in high yield, and preferably the amount of the borazane compound, which is a reaction intermediate in the final product, can be reduced. In obtaining the N-alkylborazine compound, further purification such as distillation purification can be performed after adopting the production method of the present invention, but obtaining the N-alkylborazine compound in high yield is also preferable in that the purification efficiency can be improved and a high-purity N-alkylborazine compound suitable for a film-forming material for semiconductors can be obtained. In addition, since the molecular structure is similar, the amount of the borazane compound, which is a reaction intermediate that requires time and effort to separate from the N-alkylborazine compound, can be reduced, which is also preferable in that the purification efficiency can be improved.

[0012] The stirring power is determined based on the final volume of the alkali borohydride, alkylamine salt and organic solvent. 3 It is preferable in the production method of the present invention that a stirring power in the above-mentioned range is applied at least after the total amount of the alkali borohydride and the total amount of the alkylamine salt are charged into a reaction vessel, and it is more preferable that a stirring power in the above-mentioned range is applied from the start of the reaction of the alkali borohydride and the alkylamine salt to the end of the reaction. The start of the reaction may be the time when the alkali borohydride and the alkylamine salt are mixed even partially, and the end of the reaction may be the start of cooling when the reaction solution containing the alkali borohydride and the alkylamine salt is heated and then cooled.

[0013] The stirring power is preferably 0.2 kW / m 3 More preferably, it is 0.3 kW / m 3 Above 8kW / m 3 It may be less than 5kW / m 3 The time for applying the stirring power in the above range is preferably 1 hour or more, more preferably 2 hours or more, and even more preferably 4 hours or more, and the upper limit may be 72 hours.

[0014] In the present invention, it is preferable to satisfy any one of the following requirements: (i) a step of first charging an alkali borohydride into a reaction vessel, and a step of gradually supplying an alkylamine salt to the reaction vessel containing the alkali borohydride to react the alkali borohydride and the alkylamine salt in a solvent; (ii) a step of first charging an alkylamine salt into a reaction vessel, and a step of gradually supplying an alkali borohydride to the reaction vessel containing the alkylamine salt to react the alkali borohydride and the alkylamine salt in a solvent; or (iii) a step of gradually supplying both the alkali borohydride and the alkylamine salt to the reaction vessel. By satisfying any one of these requirements, it is possible to prevent a large amount of hydrogen gas from being generated in a short time due to the reaction. Among them, the embodiment of (ii) is preferable.

[0015] In both of the above cases (i) and (ii), it is preferable to mix both the alkali borohydride and the alkylamine salt with an organic solvent. In the case of (iii), a mixture of the alkali borohydride and an organic solvent and a mixture of the alkylamine salt and an organic solvent may be prepared, and both may be gradually fed simultaneously to the reaction vessel, or one of the alkali borohydride and the alkylamine salt may be mixed with an organic solvent and the other may be prepared as a solid, and both may be gradually fed simultaneously to the reaction vessel. The above-mentioned "gradually feeding" means that the total amount is not fed all at once, but is fed in portions intermittently (intermittently) or continuously. The feeding time may be determined according to the reaction scale and the compound used, and may be, for example, fed over a period of 0.5 to 48 hours. If the feeding amount can be determined by experience or experiment, it is preferable to control the feeding to a predetermined amount, and the feeding rate of the alkali borohydride or the alkylamine salt to be gradually fed is, for example, 8 to 20 g / (L·hour) per unit volume (L) and unit time of the reaction vessel. The supply of the solvent may be automatic or manual. For example, when the production is carried out at a laboratory level, the amount of precipitation may be visually confirmed and the solvent may be appropriately supplied.

[0016] The alkali borohydride and the alkylamine salt are preferably reacted under an inert gas atmosphere. Examples of the inert gas include nitrogen gas and rare gases such as helium gas, neon gas, argon gas, krypton gas, and xenon gas. Nitrogen gas or argon gas is preferred, and nitrogen gas is particularly preferred.

[0017] When reacting an alkali borohydride and an alkylamine salt, the temperature at which the reaction proceeds, i.e., the temperature of the reaction solution from the start to the end of the reaction, is preferably 100 to 200 °C, more preferably 150 to 200 °C. It is more preferable to apply the stirring power within the above range while the reaction solution is at this temperature. During the progress of the reaction, the temperature may be constant or variable within the preferable temperature range of 150 to 200 °C. After setting the temperature to T1 (where 150 °C ≤ T1 < 200 °C), it is also preferable to raise the temperature to T2 higher than T1 (where 150 °C < T2 ≤ 200 °C). When reacting an alkali borohydride and an alkylamine salt, first, an intermediate N-alkylcycloborazane is generated. It is presumed that N-alkylborazine is generated by the release of hydrogen from N-alkylcycloborazane. The reaction for generating N-alkylborazine from this intermediate is considered to proceed at a relatively high temperature. For example, at the beginning of the reaction, the reaction solution is controlled to a low temperature T1 to generate N-alkylcycloborazane. When most of the raw materials have become N-alkylcycloborazane, it is preferable to raise the temperature of the reaction solution to T2 to complete the synthesis of N-alkylborazine. The total reaction time is, for example, 3 to 72 hours. When changing the temperature of the reaction solution from T1 to T2, it is preferable to react for 2 to 48 hours at T1 and 1 to 24 hours at T2. In the above-described aspect (i), the temperature while supplying the alkylamine salt, and in aspect (ii), the temperature while supplying the alkali borohydride are set to T1. In both cases, it is preferable to set the temperature to T2 after the supply is completed. In these cases, it is preferable to apply the above-described stirring power at least while the temperature is T2, and it is more preferable to apply the above-described stirring power at both temperatures T1 and T2. The stirring power applied while the temperature is T2 is 0.2 kW / m 3 or more or 0.3 kW / m 3 or more is particularly preferable. After the reaction is completed, it may be cooled to room temperature (about 10 to 35 °C) by allowing it to cool naturally. The reaction temperature can be measured using a temperature sensor such as a K thermocouple.

[0018] In the alkali borohydride (ABH4), A is a lithium atom, a sodium atom, or a potassium atom. Preferred examples of the alkali borohydride include sodium borohydride (NaBH4) and lithium borohydride (LiBH4), with sodium borohydride being more preferred.

[0019] In the alkylamine salt (RNH3X), R is an alkyl group and X is a halogen atom. The alkyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is not particularly limited, but is preferably 1 to 10, more preferably 1 to 8, and even more preferably 1 to 4. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a 1,2-dimethylpropyl group, a 1-ethylpropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 1-methylbutyl group, a 2-methylbutyl group, a pentyl group, an isopentyl group, a neopentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group, and a methyl group or an ethyl group is preferable. An alkyl group other than these may be used. X is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a chlorine atom. Examples of alkylamine salts include monomethylamine hydrochloride (CHNHCl), monoethylamine hydrochloride (CHCHNHCl), monomethylamine hydrobromide (CHNHBr), monoethylamine hydrofluoride (CHCHNHF). Preferably, the alkylamine salt is monomethylamine hydrochloride.

[0020] The N-alkylborazine compound obtained by the present invention is a compound represented by the following formula (I).

[0021] [ka]

[0022] In formula (I), R 1 ~R 3is the same as R in the alkylamine salt, 1 ~R 3 may be the same or different. Examples of N-alkylborazines include N,N',N''-trimethylborazine, N,N',N''-triethylborazine, N,N',N''-tri(n-propyl)borazine, N,N',N''-tri(iso-propyl)borazine, N,N',N''-tri(n-butyl)borazine, N,N',N''-tri(sec-butyl)borazine, N,N',N''-tri(iso-butyl)borazine, N,N',N''-tri(tert-butyl)borazine, N,N',N''-tri(1-methylbutyl)borazine, Examples of borazine include N,N',N''-tri(2-methylbutyl)borazine, N,N',N''-tri(neo-pentyl)borazine, N,N',N''-tri(1,2-dimethylpropyl)borazine, N,N',N''-tri(1-ethylpropyl)borazine, N,N',N''-tri(n-hexyl)borazine, N,N',N''-tricyclohexylborazine, N,N'-dimethyl-N''-ethylborazine, N,N'-diethyl-N''-methylborazine, and N,N'-dimethyl-N''-propylborazine. The borazine compound is preferably one or more of N,N',N''-trimethylborazine, N,N',N''-triethylborazine, N,N'-dimethyl-N''-ethylborazine, and N,N'-diethyl-N''-methylborazine, and is more preferably N,N',N''-trimethylborazine.

[0023] The alkali borohydride and alkylamine salt to be used may be selected according to the structure of the N-alkylborazine to be synthesized. For example, when producing N-methylborazine in which a methyl group is bonded to the nitrogen atom constituting the borazine ring, an alkylamine salt in which R is a methyl group, such as monomethylamine hydrochloride, may be used as the alkylamine salt.

[0024] The organic solvent is preferably one or more ether solvents, and examples of the ether solvent include diethyl ether, tetrahydrofuran, monoethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), and tetraethylene glycol dimethyl ether (tetraglyme). The organic solvent is more preferably one or more selected from the group consisting of monoglyme, diglyme, triglyme, and tetraglyme, more preferably one or more of triglyme and tetraglyme, and even more preferably triglyme.

[0025] The ratio of the amount of the alkali borohydride to the amount of the alkylamine salt used is not particularly limited, but it is preferable that the amount of the alkali borohydride used is 0.8 to 1.2 moles when the amount of the alkylamine salt used is 1 mole.

[0026] The total amount of the alkali borohydride and the alkylamine salt relative to the total amount of the alkali borohydride, the alkylamine salt, and the solvent used in the reaction is preferably 10 to 30 mass%, more preferably 15 to 25 mass%. In addition, in the above cases (i) and (ii), when the alkali borohydride and the alkylamine salt are mixed with an organic solvent, the amount of the alkali borohydride relative to 100 parts by mass of the organic solvent is preferably 10 to 40 parts by mass, more preferably 15 to 35 parts by mass, and the amount of the alkylamine salt relative to 100 parts by mass of the organic solvent is preferably 20 to 50 parts by mass, more preferably 25 to 40 parts by mass.

[0027] The volume of the reaction vessel is preferably 0.5 to 10,000 L, and may be 0.5 to 5,000 L, 0.5 to 1,000 L, 0.5 to 500 L, or 0.5 to 100 L, and may be appropriately set depending on the target production amount.

[0028] The stirring blade for adjusting the stirring power to the above range is preferably at least one selected from the group consisting of a propeller type, a paddle type, a turbine type, a cone type, a ribbon screw type, and a Max Blend type, and is particularly preferably a paddle type, and is also preferably one that satisfies at least one of the requirements that the number of paddle blades is 2 to 6 and that the blade is an inclined paddle type. It is also preferable to use at least one selected from the group consisting of a propeller type, a paddle type, a turbine type, a cone type, a ribbon screw type, and a Max Blend type in combination with an anchor type, and in this case, it is preferable to install the anchor type below the direction of the rotation axis. In particular, it is preferable to use an inclined paddle type blade having 2 to 6 blades in combination with an anchor type blade, with the anchor type being below the direction of the rotation axis.

[0029] The yield of N-alkylborazine obtained by the production method of the present invention is preferably 80.0% or more, more preferably 85% or more, and even more preferably 88% or more, with the upper limit being most preferably 100%, but may be around 95%.

[0030] In the production method of the present invention in which an N-alkylborazine compound is produced by reacting an alkali borohydride with an alkylamine salt, an N-alkylcycloborazane of the following formula (II) can be produced as an intermediate.

[0031] [ka] In formula (II), R 1 ~R 3 is R in formula (I) 1 ~R 3 is synonymous with.

[0032] However, in the present invention, in which a predetermined range of stirring power is applied to the reaction solution, the amount of intermediates in the final product is reduced, and the yield of N-alkylcycloborazane can be made 1.0% or less, preferably 0.9% or less, and more preferably 0.8% or less, with the lower limit being most preferably 0%, but may be around 0.1%.

[0033] In addition, the ratio of the yield (%) of N-alkylcycloborazane to the yield (%) of N-alkylborazine is preferably 0.010 or less, more preferably 0.009 or less, and even more preferably 0.008 or less, and the lower limit may be, for example, about 0.001.

[0034] The N-alkylborazine compound obtained by the present invention can be used as it is, or as a polymer obtained by polymerizing an N-alkylborazine or an N-alkylborazine derivative, for forming an interlayer insulating film for semiconductors, a barrier metal layer, an etch stopper layer, etc. EXAMPLES

[0035] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples, and can of course be modified within the scope of the above and below-mentioned aims, and all such modifications are within the technical scope of the present invention.

[0036] Example 1 A 5 L reaction vessel equipped with a cooling tube and four anchor-type and 45° paddle-type impellers as stirring blades (with the anchor-type impellers positioned downward with respect to the direction of the rotation axis) was charged with 42 g of methylamine hydrochloride as an alkylamine salt and 123 g of triglyme as a solvent while replacing the atmosphere with nitrogen, and the liquid was heated with stirring until the liquid temperature reached 150°C.

[0037] Next, the liquid temperature was kept at 150°C, and the stirring power per unit volume given to the charge liquid (a liquid consisting of 42 g of methylamine hydrochloride and 123 g of triglyme) was 0.73 kW / m 3A slurry consisting of 26 g of sodium borohydride as an alkali borohydride and 111 g of triglyme as a solvent was gradually fed into the reaction vessel over a period of 4 hours while stirring until the mixture reached a temperature of 100° C. From the change in the amount of gas discharged from the reaction vessel, it was found that hydrogen gas was steadily generated during the reaction.

[0038] After the slurry liquid was fed, the temperature of the reaction liquid (containing 42 g of the above-mentioned methylamine hydrochloride, 123 g of triglyme, 26 g of sodium borohydride, and 111 g of triglyme) was raised to 170°C, and the stirring power per unit volume given to the reaction liquid was 0.40 kW / m 3 The reaction was aged for 2 hours by stirring until the reaction temperature reached 100°C.

[0039] After the reaction was completed, the reaction solution was allowed to cool to 25°C and then analyzed by gas chromatography (GC). The reaction yield of N,N',N''-trimethylborazine and the reaction yield of the reaction intermediate N,N',N''-trimethylcycloborazane were measured by the methods described below.

[0040] Example 2 A 1 L reaction vessel equipped with a cooling tube and four anchor-type and 45° paddle-type impellers as stirring blades (with the anchor-type impellers positioned downward with respect to the direction of the rotation axis) was charged with 84 g of methylamine hydrochloride as an alkylamine salt and 246 g of triglyme as a solvent while replacing with nitrogen, and the liquid was heated with stirring until the liquid temperature reached 150°C.

[0041] Next, the temperature was kept at 150°C, and the stirring power per unit volume given to the charge liquid (a liquid consisting of 84 g of methylamine hydrochloride and 246 g of triglyme) was 0.73 kW / m 3 A slurry consisting of 52g of sodium borohydride as an alkali borohydride and 222g of triglyme as a solvent was gradually fed into the reaction vessel over a period of 4 hours while stirring until the mixture reached a temperature of 100° C. From the change in the amount of gas discharged from the reaction vessel, it was found that hydrogen gas was steadily generated during the reaction.

[0042] After the slurry liquid was fed, the temperature of the reaction liquid (containing 84 g of the above-mentioned methylamine hydrochloride, 246 g of triglyme, 52 g of sodium borohydride, and 222 g of triglyme) was raised to 170°C, and the stirring power per unit volume given to the reaction liquid was 0.40 kW / m 3 The reaction was aged for 2 hours by stirring until the reaction temperature reached 100°C.

[0043] After the reaction was completed, the reaction solution was allowed to cool to 25°C and then analyzed by gas chromatography (GC). The reaction yield of N,N',N''-trimethylborazine and the reaction yield of the reaction intermediate N,N',N''-trimethylcycloborazane were measured by the method described below.

[0044] Comparative Example 1 A 0.5 L reaction vessel equipped with a cooling tube and a half-moon impeller as a stirring blade was charged with 42 g of methylamine hydrochloride as an alkylamine salt and 123 g of triglyme as a solvent while replacing the atmosphere with nitrogen, and the liquid was heated with stirring until the liquid temperature reached 150°C.

[0045] Next, while maintaining the temperature at 150°C, the stirring power per unit volume given to the charge liquid (a liquid consisting of 42 g of methylamine hydrochloride and 123 g of triglyme) was 0.09 kW / m 3 While stirring until the temperature reached 100° C., a slurry liquid consisting of 26 g of sodium borohydride as an alkali borohydride and 111 g of triglyme as a solvent was gradually fed into the reaction vessel over a period of 4 hours to carry out the reaction.

[0046] After the slurry liquid was fed, the temperature of the reaction liquid (containing 42 g of the above-mentioned methylamine hydrochloride, 123 g of triglyme, 26 g of sodium borohydride, and 111 g of triglyme) was raised to 170°C, and the stirring power per unit volume given to the reaction liquid was 0.05 kW / m 3 The reaction was aged for 2 hours by stirring until the

[0047] After the reaction was completed, the reaction solution was allowed to cool to 25°C and then analyzed by gas chromatography (GC). The reaction yield of N,N',N''-trimethylborazine and the reaction yield of the reaction intermediate N,N',N''-trimethylcycloborazane were measured by the method described below.

[0048] In the examples and comparative examples, the reaction solution was analyzed by gas chromatography under the following conditions, and the yields of N,N',N''-trimethylborazine and N,N',N''-trimethylcycloborazane were calculated based on the charged amount of methylamine hydrochloride. Equipment: Shimadzu Corporation GC-2014 Column: Frontier Labs Ultra Alloy-1 Carrier gas: Nitrogen Carrier gas flow rate: 3.0 mL / min Sample injection temperature: 200℃ Detector temperature: 280℃ Sample injection volume: 0.2 μL Column temperature: 50°C (4 min), heated to 280°C at a rate of 20°C / min, 280°C (15 min)

[0049] The results are shown in Table 1.

[0050] [Table 1]

[0051] From the above, in the method for producing an N-alkylborazine compound, the stirring power per unit volume given to the reaction solution is set to 0.1 to 10 kW / m 3 It was found that by stirring while maintaining the temperature at 100° C., N-alkylborazine compounds can be obtained in high yields. In addition, it was found that the amount of N-alkylcycloborazane, a reaction intermediate, can be reduced, making it easy to obtain high-purity N-alkylborazine compounds.

Claims

1. A.B.H. ４ (A is a lithium atom, a sodium atom, or a potassium atom) and an alkali borohydride represented by RNH ３ A method for producing an N-alkylborazine compound by reacting an alkylamine salt represented by X (R is an alkyl group and X is a halogen atom) in an organic solvent, comprising the steps of: Using at least one stirring blade selected from the group consisting of a propeller type, a paddle type, a turbine type, a cone type, a ribbon screw type, and a Maxblend type, a total volume of 1 m of the reaction solution containing the alkali borohydride, the alkylamine salt, and the organic solvent is increased. ３ The method for producing an N-alkylborazine compound comprises: stirring the reaction solution with a stirring power of 0.1 to 10 kW per minute, and reacting the alkali borohydride with the alkylamine salt.

2. The method of claim 1, wherein the yield of the reaction intermediate N-alkylcycloborazane is 1.0% or less.

3. The method according to claim 1 or 2, wherein the alkali borohydride and the alkylamine salt are reacted at 100 to 200° C.

4. The method according to claim 3, wherein the alkali borohydride and the alkylamine salt are reacted at a temperature T1 of 150° C. or more and less than 200° C., and then at a temperature T2 of more than 150° C. and less than 200° C., and the stirring power is applied at least while the temperature is T2.

5. The alkali borohydride is sodium borohydride (NaBH ４ 3. The method according to claim 1 or 2, wherein

6. The alkylamine salt is monomethylamine hydrochloride (CH ３ N.H. ３ 3. The method according to claim 1, wherein the compound is selected from the group consisting of fluorine, fluorine, chlorine, fluor ...

7. 3. The method according to claim 1, wherein the organic solvent is at least one selected from the group consisting of monoglyme, diglyme, triglyme, and tetraglyme.

8. The process according to claim 1 or 2, wherein the alkali borohydride and the alkylamine salt are reacted in a reaction vessel having a volume of 0.5 to 10,000 L.

Images