JP2007077038A - Method for producing crystalline n-nitroso-n-phenylhydroxylamine aluminum salt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the control of a reaction system in the production of a crystalline N-nitroso-N-phenylhydroxylamine aluminum salt and solve various problems on environment and working hygiene. <P>SOLUTION: The production method comprises the first step to drop nitrobenzene into a liquid mixture of a lower alcohol and water containing metallic zinc powder and ammonium chloride to form N-phenylhydroxylamine, the second step to drop an alkyl nitrite to the N-phenylhydroxylamine obtained by the first step in the presence of ammonium carbamate, ammonium bicarbonate or ammonium carbonate to obtain N-nitroso-N-phenylhydroxylamine ammonium salt and the third step to react cupferron obtained by the second step with an aluminum compound, dissolve the produced N-nitroso-N-phenylhydroxylamine aluminum salt in ethyl acetate or chloroform and reflux the product with a lower alcohol by heating. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing crystalline N-nitroso-N-phenylhydroxylamine aluminum salt and improvement of each step in the production method.

  N-nitroso-N-phenylhydroxylamine aluminum salt (hereinafter sometimes abbreviated as “NPAL”) is an analytical reagent (Non-Patent Documents 1 and 2), and improves the quality of synthetic resins utilizing polymerization inhibition. (Patent Documents 1 to 6) are useful compounds as additives for NPAL (4) is produced according to the following reaction scheme using nitrobenzene (1) as a raw material.

  The reduction of nitrobenzene (1), which is the first step, is performed by adding zinc powder to a reaction system consisting of nitrobenzene, ammonium chloride and water in an open system as shown in Non-Patent Document 3. . Ammonium chloride is necessary for the activation of zinc and is used in a large amount of about 0.5 to 1 molar equivalent to the amount of zinc. Since this reaction involves a vigorous exothermic reaction, it becomes difficult to control the reaction in a large amount of operation. Furthermore, since the reaction is carried out in an open system, that is, in the atmosphere, azoxybenzene (5) is not a little produced as a by-product (Non-patent Document 4), and the yield is difficult to improve (yield about 65%).

Furthermore, since ethyl ether is used when extracting the produced N-phenylhydroxylamine (2), there remains a problem in terms of safety.
Some improvements to this process have been reported. For example, in order to increase the solubility of nitrobenzene (1), 30% ethanol is used as a solvent (Non-Patent Document 5), or the reaction temperature is decreased (Non-Patent Document 6). However, these methods are also carried out in an open system in which zinc powder is intermittently added to a solution containing nitrobenzene.

Many other methods of synthesizing N-phenylhydroxylamine (2) by reduction of nitrobenzene (1) have been reported. For example, NH ₂ NH ₂ .H ₂ O / Rh-C (Non-Patent Document 7), NH ₂ NH ₂ .H ₂ O / RaneyNi (Non-Patent Document 8), NaBH ₄ / Sb (Non-Patent Document 4), KBH ₄ This is a method of reducing nitrobenzene with / BiCl ₃ (Non-patent document 9), i-Bu ₂ AlH (Non-patent document 10), or the like. However, from the viewpoint of an industrial production method, any method has problems such as economy, operability, and by-product generation.

In the second step, N-phenylhydroxylamine (2) to N-nitroso-N-phenylhydroxylamine ammonium salt (hereinafter sometimes referred to as “cuperon”) (3) was synthesized by N-phenylhydroxylamine ( This is carried out by dropping butyl nitrite into the ethyl ether solution of 2) while passing ammonia gas (Non-patent Document 11). However, the management of ammonia gas is not always easy, and in this method, excess ammonia gas is discharged out of the system, which causes a problem in terms of work hygiene and environment. In order to improve this defect, a method using 28% aqueous ammonia instead of ammonia gas has been submitted (Patent Document 7). However, since N-nitroso-N-phenylhydroxylamine ammonium salt (3) is readily soluble in water, the remaining water after ammonia in 28% ammonia water participates in the reaction, so that several percent of ammonium salt (3 ) Was found in the additional test.
Analytical chemistry 25, 103 (1976) Analytical chemistry 38, 267 (1989) Org. Synth. Coll. Vol. I, 445 Synthetic Commun. 27, 1547 (1997) Org. Prep. Proceed. Int. 30, 439 (1998) Bioorg. Med. Chem. 8, 405 (2000) Org. Synth. Coll. Vol. VIII, 16 Synthesis 1984, 938 Synthetic Commun. 27, 3497 (1997) J. Org. Chem. 50, 2443 (1985) Org. Synth. Coll. Vol. I, 177 JP 2004-191585 A JP 2004-168896 A JP 2004-40639 A JP 2002-139828 A JP 11-29740 A JP-A-6-143414 Japanese Patent Publication No.58-1110

  The present invention has been made in view of the prior art as described above, and facilitates control of a reaction system in a series of steps in the production of NPAL, and further solves various environmental and occupational health problems. It is an object.

  For this reason, in this invention, examination was performed in each process of NPAL manufacture, and the novel manufacturing method of N-phenylhydroxylamine (2) and cuperone (3) which are intermediates was also completed.

The gist of the present invention aimed at solving such problems is as follows.
[1] A first step of obtaining N-phenylhydroxylamine by adding nitrobenzene dropwise to a mixed liquid of a lower alcohol having 1 to 3 carbon atoms containing metal zinc powder and ammonium chloride and water;
In the lower alcohol solution or ethyl acetate solution of N-phenylhydroxylamine obtained in the first step, any one of ammonium carbamate, ammonium bicarbonate, and ammonium carbonate coexists, and alkyl nitrite (alkyl: propyl, isopropyl, Butyl, isobutyl) is added dropwise, and the operon obtained in the second step is reacted with an aluminum compound in a mixed solvent of water and ethyl acetate or chloroform, and the resulting NPAL is reacted with ethyl acetate or A method for producing crystalline NPAL comprising a third step of dissolving in chloroform and heating to reflux with a lower alcohol.
[2] A method for producing N-phenylhydroxylamine, wherein nitrobenzene is added dropwise to a mixed liquid of a C 1-3 lower alcohol containing metal zinc powder and ammonium chloride and water.
[3] Alkyl nitrite (alkyl: propyl, isopropyl, butyl, isobutyl) by coexisting any one of ammonium carbamate, ammonium bicarbonate, and ammonium carbonate in a lower alcohol solution or ethyl acetate solution of N-phenylhydroxylamine A method for producing cuperon, in which a solution is dropped.
[4] An aqueous solution of any one of ammonium carbamate, ammonium hydrogen carbonate, and ammonium carbonate coexists in an ethyl acetate or chloroform solution of N-phenylhydroxylamine, and alkyl nitrite (alkyl: propyl, isopropyl, butyl, isobutyl). ), Followed by dropwise addition of an aqueous solution of an aluminum compound, the resulting NPAL is dissolved in ethyl acetate or chloroform, and heated to reflux with a lower alcohol.

According to the NPAL production method of the present invention, the reaction system can be easily controlled, and various environmental and occupational health problems can be solved.
Moreover, according to this invention, the novel manufacturing method of N-phenylhydroxylamine (2), a cuperon (3), and crystalline NPAL (4) is provided.

Hereinafter, the present invention will be described more specifically.
The method for producing NPAL according to the present invention includes the following steps.
1st process: Nitrobenzene is dripped at the liquid mixture of C1-C3 lower alcohol containing metal zinc powder and ammonium chloride, and water is subsequently refluxed, N-phenylhydroxylamine (2) is obtained.

  Second step: An alkyl nitrite (alkyl: propyl) in the presence of any one of ammonium carbamate, ammonium hydrogen carbonate or ammonium carbonate in the lower alcohol or ethyl acetate solution of N-phenylhydroxylamine obtained in the first step. , Isopropyl, butyl, isobutyl, etc.) are added dropwise to obtain cuperone.

Third step: The operon obtained in the second step is reacted with an aluminum compound, followed by treatment with a lower alcohol to obtain crystalline NPAL.
Hereinafter, the above process will be described in more detail.
First step:
In the first step of obtaining N-phenylhydroxylamine, metal zinc powder and ammonium chloride are charged in advance in a mixture of a lower alcohol having 1 to 3 carbon atoms and water, and nitrobenzene is dropped into this reaction system, Stir with heat. Of the lower alcohols, methanol is particularly preferred, and the reaction can proceed at the reflux temperature of methanol. Thus, since the reaction is carried out at the reflux temperature of methanol, the reaction system can be easily controlled even in a large amount of operation. In addition, the reaction in a closed system is possible, and the formation of oxides can be prevented by performing the reaction preferably in an inert atmosphere such as nitrogen.

  Ammonium chloride is used for the activation of zinc. When the amount of ammonium chloride used is large, the reaction rate is accelerated. For this reason, in the conventional reaction system, an approximately equimolar amount of ammonium chloride with zinc is used. It has been found that by employing the reaction system of the present invention, zinc can be activated even with a small amount of ammonium chloride. In addition, it is clear that the use of ammonium chloride of 0.25 molar equivalent or more with respect to zinc in this operation tends to agglomerate the zinc powder and make it agglomerated, leading to a reduction in the yield of the reduction product. became.

  The amount of zinc used theoretically requires 2 gram atoms per mole of nitrobenzene, but it is desirable to use it in a slightly excessive amount. Preferably it is 2-2.5 gram atom, More preferably, it is 2.1-2.3 gram atom.

  The usage-amount of ammonium chloride is 0.05-0.5 mol with respect to 1 mol of nitrobenzene, More preferably, it is 0.1-0.3 mol. Therefore, the amount of ammonium chloride used for zinc is preferably 0.05 to 0.15 molar equivalent. This amount is about 1/10 of the conventional method.

Water is involved in the reduction reaction of nitrobenzene with zinc. Theoretically, 1 mol (Non-patent Document 3) or 5 mol of water (US Pat. No. 3,413,349) is required for 1 mol of nitrobenzene.
In the reaction system of the present invention, the amount of water used is preferably 5 to 25 mol, more preferably 7 to 20 mol, per 1 mol of nitrobenzene. The proportion of the alcohol in the mixture of the lower alcohol having 1 to 3 carbon atoms and water as the reaction solvent is desirably dissolved at the reaction temperature, preferably 30 to 90 v / v%, more preferably 50 to 85%. It is.

The reaction time was TLC (SiO ₂ -hexane: ethyl acetate = 1 after dropwise addition of nitrobenzene.
In 1), it is determined appropriately by monitoring the completion of the reaction. For example, when the alcohol is methanol, the reaction is completed in about 0.5 to 2 hours at the methanol reflux temperature.

After completion of the reaction, zinc oxide is separated off to obtain a lower alcohol solution of N-phenylhydroxylamine. Since the stability of N-phenylhydroxylamine is not high, the lower alcohol solution can be supplied to the second step without separating N-phenylhydroxylamine from this filtrate. Alternatively, the filtrate may be concentrated under reduced pressure, and the resulting crude N-phenylhydroxylamine may be dissolved in ethyl acetate. This operation removes ammonium chloride. This ethyl acetate solution can also be supplied to the second step as it is. Further, the ethyl acetate solution is concentrated, and the remainder is washed with hexane or cyclohexane, whereby N-phenylhydroxylamine is obtained as colorless needle crystals in a high yield of 80 to 90%. The crystals turn gray when left in air at room temperature for 12 hours, but are stable when stored in a freezer.
Second step:
Any one of ammonium carbamate, ammonium bicarbonate, and ammonium carbonate is added to the lower alcohol or ethyl acetate solution of N-phenylhydroxylamine obtained in the first step, and alkyl nitrite (alkyl: propyl, isopropyl, butyl, Isoperyl etc.) is added dropwise to obtain cuperone.

In this reaction, since any one of solid ammonium carbamate, ammonium hydrogen carbonate, and ammonium carbonate is used without using ammonia gas, a stoichiometrically accurate amount can be used, and operability is also good. It can be safely implemented without environmental problems. In addition, the said solid ammonium salt and concentrated ammonia water can also be used in combination. This combination can reduce the loss of cuperone due to water. Furthermore, since a lower alcohol or ethyl acetate having 1 to 3 carbon atoms is used as a reaction solvent instead of ethyl ether, safety is high.

The reaction temperature may be slightly higher than that of a general nitrosation reaction, and can usually be carried out at 15 ° C. or lower. Since ethyl acetate is a difficult solvent for cuperone, by using the reaction solvent as a reaction solvent, the reaction solution is filtered after completion of the reaction, whereby high-purity cuperone is obtained as white flaky crystals.
Third step:
Finally, the operon obtained in the second step is reacted with an aluminum compound to obtain NPAL.

This reaction itself is publicly known, and the methods described in Non-Patent Documents 1 and 2, Anal. Chim. Acta 3, 191 (1949), Z. Naturforschung, Theil B, 29, 24 (1974) and the like are particularly limited. Can be adopted without

  In any of the methods described in these documents, an aqueous solution of cupron and an aqueous solution of aluminum chloride, aluminum nitrate, aluminum alum and the like as an aluminum compound are mixed, and the produced white solid is filtered, washed and dried. NPAL is obtained. The white solid obtained here is in the form of powder and there is no description of the specific melting point.

  In the NPAL production method according to the present invention, chloroform or ethyl acetate is laminated on an aqueous solution of cuperone at room temperature, and an aqueous solution of an aluminum compound such as aluminum chloride, aluminum nitrate, aluminum alum or the like is dropped with stirring. The resulting white insoluble material immediately dissolves in the organic layer. The organic layer is separated, dried over anhydrous sodium sulfate, and the solvent is distilled off. When the residue is heated to reflux with a lower alcohol, crystalline NPAL is obtained as white to slightly yellowish white prism crystals. The melting point is 169-172 ° C.

  The method for producing the crystalline NPAL according to the present invention is carried out by continuously carrying out the first to third steps, but can also be carried out without separating the cupron. An aqueous solution of any one of ammonium carbamate, ammonium hydrogen carbonate or ammonium carbonate is added to a chloroform or ethyl acetate solution of N-phenylhydroxylamine obtained in the first step, and the alkyl nitrite is preferably stirred at 15 ° C. or lower with stirring. (Alkyl: propyl, isopropyl, butyl, isobutyl) is added dropwise. Subsequently, an aqueous solution of aluminum chloride is dropped as an aluminum compound, and the organic layer is separated. After drying, the solvent is distilled off, and the residue is heated to reflux with a lower alcohol to obtain crystalline NPAL in high yield.

By adopting such a process, operability and safety are improved, and crystalline NPAL can be obtained in a high yield.
The first step is a novel process for producing N-phenylhydroxylamine. Therefore, the present invention also includes a method for producing N-phenylhydroxylamine in which nitrobenzene is added dropwise to a mixture of a lower alcohol having 1 to 3 carbon atoms containing metal zinc powder and ammonium chloride and water in a nitrogen atmosphere and heated. Is done.

Furthermore, the second step is also a new method for producing cuperon. Therefore, in the present invention, any one of ammonium carbamate, ammonium bicarbonate, and ammonium carbonate is allowed to coexist in a lower alcohol solution or ethyl acetate solution of N-phenylhydroxylamine, and alkyl nitrite (alkyl: propyl, isopropyl, butyl). , Isobutyl) is also included.
(Example)
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
Melting | fusing point measurement Melting | fusing point was measured based on the 14th revision Japanese Pharmacopoeia, a general test method, and a melting | fusing point measuring method (2001). In this measurement method, a capillary is filled with a sample and measured with a melting point measuring device.
(Example 1) Synthesis of N-phenylhydroxylamine A reaction vessel containing 28.1 g (0.43 g.atom) of zinc powder and 1.07 g (0.02 mol) of ammonium chloride was stirred with stirring in a nitrogen atmosphere. 165 ml of% v / v methanol / water is added, and 24.6 g (0.2 mol) of nitrobenzene is added dropwise over 20 minutes while stirring at a bath temperature of 55 °. The reaction liquid rises to 70 °. Increase bath temperature to 65 ° and heat for an additional hour. When monitored by TLC (SiO ₂ -hexane, ethyl acetate = 1: 1), nitrobenzene almost disappears (Rf value: N-phenylhydroxylamine, 0.23; nitrobenzene, 0.59). Zinc oxide is filtered off and washed with 2 x 10 ml of methanol. (B) Washing solution is concentrated under reduced pressure, and the residue is dissolved in 120 ml of ethyl acetate and dried over anhydrous magnesium sulfate. The pale yellow solid obtained by distilling off ethyl acetate is washed with 50 ml of hexane. 19.6 g (yield 89.8%) of colorless needle crystals having a melting point of 79-80 ° C. are obtained. Recrystallization from cyclohexane gives colorless needles with a melting point of 80-80.5 ° C.

¹ H-NMR (300 MH, DMSO-d ₆ ) δ 6.74 (t, J = 7.3, 4-H), 6.84 (d, J = 7.3, 2-H and 6-H), 7.16 (t, J = 7.4, 3-H and 5-H), 8.23 and 8.28 (s, OH and NH)
Elemental analysis: C ₆ H ₇ NO
Calculated: C, 66.03; H, 6.47; N, 12.84
Found: C, 65.79; H, 6.57; N, 12.91
(Example 2)
Zinc dust 71.9 g (1.1 g.atom), ammonium chloride 6.75 g (0.125 mol), 50% v / v isopropanol / water 350 ml, nitrobenzene 61.6 g (0.5 mol)
And processing as in Example 1. The obtained yellow-orange crude solid is heated to reflux with 100 ml of cyclohexane, allowed to cool and ice-cooled to obtain 44.95 g of colorless needle crystals having a melting point of 80 to 80.5 ° C. (yield 82.4%).
Example 3 Synthesis of Cuperone Into a mixture of 5.46 g (50 mmol) of N-phenylhydroxylamine, 2.15 g (27.5 mmol) of ammonium carbamate and 55 ml of ethyl acetate, butyl nitrite 5. 54 g (53.8 mmol) are added dropwise at 10 ° C. or lower. The reaction is returned to room temperature and stirred for 1 hour. White crystals are collected by filtration, washed with cold ethyl acetate (10 ml × 2) and dried. 7.38 g of white flaky crystals are obtained. Yield 95.2%
Recrystallization from ethanol gives white flaky crystals with a melting point of 154 ° C. (decomposition).

¹ H-NMR (300 MH, DMSO-d ₆ ) δ 7.26 (t, J = 7.4, 4-H), 7.38 (t, J = 7.4, 3-H and 5-H), 7.87 (d, J = 7.4, 2-H and 6-H), 7.64 (b, NH ₄ ).

Elemental analysis: C ₆ H ₉ N ₃ O ₂
Calculated values: C, 46.44; H, 5.85; N, 27.09
Found: C, 46.41; H, 5.84; N, 27.00
Example 4 Synthesis of Cuperone by Two-Step Succession A mixture of zinc powder 43.14 g (0.66 g.atom), ammonium chloride 3.24 g (0.06 mol), 70% v / v isopropanol / water 180 ml, Nitrobenzene 36.93g
(0.3 mol) is reacted as in Example 1. After the zinc oxide is filtered off and the filtrate is concentrated, the residue is dissolved in 200 ml of ethyl acetate. To this ethyl acetate solution, 6.9 g (0.075 mol) of ammonium carbonate is added and cooled to 0 ° C. While stirring efficiently, 9.5 ml (0.15 mol) of about 30% aqueous ammonia is added, followed by dropwise addition of 30.94 g (0.3 mol) of isobutyl nitrite at 10 ° C. or lower. Stirring is continued for 30 minutes after the dropwise addition, and the produced crystals are collected by filtration and washed with cold acetone 20 ml × 3. 37.36 g (80.3%) of white flaky crystals are obtained. Melting point: 153.5-154 ° C (decomposition)
(Example 5) Synthesis of crystalline NPAL A solution prepared by dissolving 10.91 g (0.1 mol) of N-phenylhydroxylamine in 50 ml of ethyl acetate and dissolving 4.83 g (0.0525 mol) of ammonium carbonate in 25 ml of water And cool to 0 ° C. While stirring, 10.83 g (0.105 mol) of isobutyl nitrite is added dropwise so that the reaction temperature does not exceed 10 ° C. After stirring for 10 minutes, the cooling bath is removed, the temperature is returned to room temperature, and the mixture is further stirred for 30 minutes. Cuperon is deposited on the entire surface. A solution prepared by dissolving 8.04 g (0.0333 mol) of aluminum chloride hexahydrate in 20 ml of water is added dropwise to the reaction solution. The ethyl acetate layer is separated and dried over anhydrous sodium sulfate, and about 30 ml of ethyl acetate is distilled off. While the remaining ethyl acetate solution is heated to reflux, 40 ml of isopropanol is gradually added and allowed to cool with stirring. The precipitated white crystals are collected by filtration, washed with isopropanol and dried. 13.54 g (92.7%) of NPAL having a melting point of 169.5 to 170.5 ° is obtained as white prism crystals.

¹ H-NMR (300 MH, DMSO-d ₆ ) δ 7.45 to 7.51 (m, 9H), 8.02 to 8.04 (m, 6H).
Elemental _{analysis: C 18 H 15 N 6 O} 6 Al
Calculated: C, 49.32; H, 3.45; N, 19.18
Found: C, 49.31; H, 3.47; N, 19.56
(Example 6)
A solution prepared by dissolving 10.91 g (0.1 mol) of N-phenylhydroxylamine in 50 ml of chloroform and 8.30 g (0.105 mol) of ammonium hydrogen carbonate in 30 ml of water is added and cooled to 0 ° C. Thereafter, the same treatment as in Example 5 is carried out to obtain 13.2 g (90.3%) of white prism crystals.
Melting point: 169.5 to 171 ° C
(Example 7)
4.65 g (0.03 mol) of cuperon was dissolved in 45 ml of water, 40 ml of ethyl acetate was added, and 2.41 g (0.01 mol) of aluminum chloride hexahydrate was dissolved in 20 ml of water while stirring well. Add the solution at room temperature. Stir for another 10 minutes and separate the ethyl acetate layer. After drying over anhydrous sodium sulfate, ethyl acetate is concentrated under reduced pressure. The slightly yellow gum residue is refluxed with 30 ml of ethanol. Soon white crystals will precipitate. The product is allowed to cool as it is, and 4.21 g (yield 96.1%) of white to pale yellowish white prism crystals are obtained. Melting point 170-171 ° C

According to the NPAL production method of the present invention, the reaction system can be easily controlled, and various environmental and occupational health problems can be solved.
Moreover, according to this invention, the novel manufacturing method of N-phenylhydroxylamine (2), a cuperon (3), and crystalline NPAL (4) is provided.

Claims (4)

A first step of obtaining N-phenylhydroxylamine by heating nitrobenzene dropwise to a mixed solution of a lower alcohol having 1 to 3 carbon atoms containing metal zinc powder and ammonium chloride and water;
In the lower alcohol solution or ethyl acetate solution of N-phenylhydroxylamine obtained in the first step, any one of ammonium carbamate, ammonium bicarbonate, and ammonium carbonate coexists, and alkyl nitrite (alkyl: propyl, isopropyl, Butyl, isobutyl) is added dropwise to obtain N-nitroso-N-phenylhydroxylamine ammonium salt, and N-nitroso-N-phenylhydroxylamine ammonium salt obtained in the second step is mixed with water and acetic acid. Crystallinity comprising a third step of reacting with an aluminum compound in a mixed solvent of ethyl or chloroform, transferring the produced N-nitroso-N-phenylhydroxylamine aluminum salt into ethyl acetate or chloroform, and heating to reflux with a lower alcohol. N-nitroso- A method for producing N-phenylhydroxylamine aluminum salt. A method for producing N-phenylhydroxylamine, comprising heating nitrobenzene dropwise to a mixed solution of a lower alcohol having 1 to 3 carbon atoms containing metal zinc powder and ammonium chloride and water. Any one of ammonium carbamate, ammonium hydrogen carbonate, and ammonium carbonate coexists in a lower alcohol solution or ethyl acetate solution of N-phenylhydroxylamine, and alkyl nitrite (alkyl: propyl, isopropyl, butyl, isobutyl) is added dropwise. , Method for producing N-nitroso-N-phenylhydroxylamine ammonium salt. An aqueous solution of any one of ammonium carbamate, ammonium bicarbonate, and ammonium carbonate coexists in an ethyl acetate or chloroform solution of N-phenylhydroxylamine, and alkyl nitrite (alkyl: propyl, isopropyl, butyl, isobutyl) is added dropwise. Subsequently, an aqueous solution of an aluminum compound is dropped, and the produced N-nitroso-N-phenylhydroxylamine aluminum salt is dissolved in ethyl acetate or chloroform, and crystalline N-nitroso-N-phenyl is heated to reflux with a lower alcohol. Method for producing hydroxylamine aluminum salt.