JPH0446262B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing aminobenzylamine, and in particular provides a method that is extremely advantageous for industrial implementation. For more details, see the general formula () (In the formula, the nitro group is at m-position or p-position) Aminobenzyl characterized by catalytic reduction of nitrobenzaldoxime in the presence of boric acid, phosphoric acid and/or anhydride thereof. The present invention relates to a method for producing an amine. Aminobenzylamine is an epoxy resin curing agent,
It is an important material that is a raw material for polyamides and polyimides, and for agricultural and pharmaceutical intermediates. Conventionally, aminobenzylamine is produced by using nitrobenzaldehyde or nitrobenznitrile as a starting material. for example,
As a method using the former as a starting material, there are the following methods. (a) Nitrobenzyl bromide is derived from nitrobenzaldehyde, then reacted with potash phthalimide to obtain N-(m-nitrobenzyl)-phthalimide, and then m-
-Aminobenzylamine was obtained with a yield of about 20% (N. Kornblum et al., J. Am. Chem. Soc.,
71--2137 (1949)). (b) m-Nitrobenzaldehyde is reacted with phenylhydrazine to obtain a hydrazone compound, which is catalytically reduced to give m-aminobenzylamine.
obtained with a yield of 60% (A. Siddiqui et al., Synth
Commn 7-, 71-78 (1977)). (c) m-nitrobenzaldoxime was obtained from m-nitrobenzaldehyde, and this was subjected to high-pressure catalytic reduction using a Raney-nickel catalyst to obtain m-aminobenzylamine in a yield of 52% (JR
Griffith et al., NRL Report 6439). On the other hand, as a method using the latter as a starting material, there are the following methods. (d) p derived from p-nitrobenzonitrile
-aminobenzonitrile was reduced with lithium aluminum hydride to obtain p-aminobenzylamine in 37% yield (NCBrown et al.
J. Wedicinal Chem., 20--1189 (1977)). (e) m-Nitrobenzonitrile was subjected to high-pressure catalytic reduction using a Raney Nickel catalyst to obtain m-aminobenzylamine in a yield of 49% (JR
Griffith et al., NRL Report 6439). As described above, in the production of aminobenzylamine by known methods, as in (a) and (b), an intermediate is produced using more than an equivalent amount of relatively expensive compounds such as potassium phthalimide and phenylhydrazine. ,
The target product is obtained by reducing this, but these methods are not economical because the reaction steps are long and recovery of by-products requires expense and labor. Method (d) also has the disadvantage that the reducing agent is expensive and difficult to handle. As in (c) and (e), using a Raney nickel catalyst,
It is clear that the method of high-pressure catalytic reduction in an autoclave is disadvantageous in that the equipment is expensive and the volumetric efficiency is low. Generally, the method of producing benzylamine by a conventional reduction method of benzonitrile or benzaldoxime produces a secondary amine and ammonia as by-products, so the yield of benzylamine is low. For example, benzonitrile in ethanol, Ni
When catalytically reduced under a catalyst, the benzylamine yield is
40-50%, dibenzylamine yield 20% (Chemical Society of Japan, "Experimental Chemistry Course" Volume 17 (2), Maruzen,
313 pages (1956)). Also, benzaldoxime in water-alcohol,
Catalytic reduction in contact with Pd colloid gives a benzylamine yield of 47% and a dibenzylamine yield of 41% (Wl. Gulewitsch, Ber., 57--, 1645 (1924)). This is because benzalimine is initially generated during the reduction of benzonitrile and benzaldoxime, and is an intermediate in the reduction reaction system, such as by-product of benzaldehyde accompanying the hydrolysis reaction of benzalimine and condensation of benzalimine and benzaldehyde. This is due to the low yield of benzylamine due to the formation of by-products due to various reactions. Therefore, by suppressing the production of such byproducts,
In order to improve the yield of benzylamine, a method using acetic anhydride or dry hydrogen chloride during reduction has been proposed. For example, in the method using acetic anhydride, when benzonitrile is reduced with 2.65 times the mole of acetic anhydride, benzylamine is obtained with a yield of 69%, and when similarly reduced with 12.7 times the mole of acetic acid, the yield is equivalent to 91%. benzylamine has been obtained (WH Carothers et al.
J.Am.Chem, Soc., 47D～～3051～3057 (1925),
FEGould et al., J.Org.Chem., 25--1658-1660
(1960)). Furthermore, after isolating benzaldoxime acetate from benzaldoxime and acetic anhydride, it was reduced to obtain benzylamine with a yield of 91% (KW Rosenmund et al., Ber., 56--2258-
2262 (1923)). These methods of reducing benzonitrile and benzaldoxime in an acetic anhydride solvent are all N-
It is isolated as acetylbenzylamine and hydrolyzed to produce benzylamine. On the other hand, in the method using hydrogen chloride, when the amount of dry hydrogen chloride gas used is 1 equivalent or more in the case of benzonitrile and 3 equivalents or more in the case of benzaldoxime, benzylamine can be obtained in high yield in both cases. (WHHartung, J.Aw, Chem, Soc.,
50~~3370~3374 (1928)). In this way, when benzonitrile or benzaldoxime is reduced to produce benzylamine,
The method of using acetic anhydride or dry hydrogen chloride is effective for improving the yield, but acetic anhydride and dry hydrogen chloride have the effect of stabilizing the intermediate during reduction as described above, and benzaldoxime has the effect of stabilizing the intermediate during reduction. However, this method using acetic anhydride or dry hydrogen chloride is not economical because it requires the use of a large amount of relatively expensive acetic anhydride. In addition, when dry hydrogen chloride is used, it is necessary to use the solvent in an anhydrous state, and hydrogen absorption is slow, so it is necessary to use a dilute solution, and catalyst deterioration is There is a very serious drawback. Furthermore, there are also problems with the material of the device. When reducing nitrobenzaldehyde using this method, in addition to the above-mentioned problems, a more complicated reaction is expected due to the presence of a nitro group. In other words, reactions with amino groups generated by reduction of nitro groups, hydrolysis accompanied by by-product water, side reactions of aminobenzaldehyde generated by this hydrolysis, etc. can be considered, and these side reactions can be suppressed. In order to do this, it is necessary to use a large amount of acetic anhydride or dry hydrogen chloride. Therefore, it must be said that it is extremely difficult to industrially produce aminobenzylamine using such a technical background and known methods. The present inventors have intensively studied a method for producing aminobenzylamine that does not have the above drawbacks. As a result, high yields can be obtained by using nitrobenzaldoxime, which can be easily produced from nitrobenzaldehyde, as a raw material and catalytically reducing it using a reduction catalyst in the presence of relatively inexpensive boric acid, phosphoric acid, and/or their anhydrides. It was discovered that aminobenzylamine could be produced using the method of the present invention, and the method of the present invention was completed. That is, the method of the present invention is based on the general formula () (In the formula, the nitro group is at m-position or p-position) Aminobenzylamine characterized by contacting nitrobenzaldoxime in the presence of boric acid, phosphoric acid and/or anhydride thereof. This is a manufacturing method. In the method of the present invention, reduction is carried out in an organic solvent in the presence of boric acid, phosphoric acid and/or anhydrides thereof. Therefore, the intermediate product exists in a stable form as a mineral acid salt of aminobenzylamine. That is, by stabilizing various intermediates such as amines and imines generated during reduction as borates and phosphates, and reducing the basicity of the amino groups and imino groups of the borates and phosphates, Decomposition and side reactions are suppressed, and as a result, the reduction of the nitro group to the amino group and the reduction of the aldoxime group to the aminomethyl group proceed rapidly, and the target product, aminobenzylamine, can be selectively produced. Furthermore, in the case of the anhydrides diboron trioxide (boric anhydride) and phosphorus pentoxide (phosphoric anhydride), three molecules of water produced by the reduction reaction of nitrobenzaldehyde are obtained, and two molecules of boric acid and phosphoric acid, respectively, are obtained. Therefore, one of its characteristics is that side reactions such as hydrolysis reactions do not occur at all. Furthermore, the method of the present invention has the great advantage that the activity of the catalyst does not decrease. For this reason,
After recovery, it can be used repeatedly and is extremely economically advantageous. After the reaction is completed, aminobenzylamine can be easily isolated by separating and purifying it as a borate or phosphate, or by distilling and purifying it by simple neutralization, which is extremely advantageous industrially. The raw material used in the method of the present invention is m-nitrobenzaldoxime or p-nitrobenzaldoxime, which can be easily produced by reacting the corresponding nitrobenzaldehyde with an industrially inexpensive hydroxyamine. Next, the mineral acid used in the method of the present invention is boric acid, phosphoric acid, boric anhydride or phosphoric acid anhydride (hereinafter referred to as mineral acid), and preferably boric acid and boric anhydride cause the least deterioration of the catalyst. The amount of these mineral acids used is based on the raw material nitrobenzaldoxime.
It is appropriate to use 0.2 equivalent or more, preferably 1 to 3 equivalents. Mineral acids are used in a state where they are dissolved or suspended in a solvent together with raw materials. In this case, there is no problem in using either alone or in combination of two or more kinds. Examples of this solvent include methanol, ethanol isopropyl alcohol,
n-butyl alcohol, sec-butyl alcohol,
Alcohols, glycols, and ethers such as methyl cellosolve, ethyl cellosolve, ethylene glycol, propylene glycol, diglyme, tetraglyme, dioxane, and tetrahydrofuran are preferably used, and in some cases, hexane, cyclohexane, benzene, toluene, Aliphatic hydrocarbons, aromatic hydrocarbons, esters, and halogenated hydrocarbons such as ethyl acetate, butyl acetate, dichloromethane, chloroform, and 1,1,2-trichloroethane can also be used. These solvents may be used alone or in combination of two or more, and water-containing solvents may also be used. The amount of the solvent to be used is not particularly limited, but usually 1 to 15 times the weight of the raw material is sufficient. In the method of the present invention, commonly used reduction catalysts such as nickel, palladium, platinum, rhodium, ruthenium, cobalt, copper, etc. can be used as the reduction catalyst in the catalytic reduction. Industrially it is preferred to use palladium catalysts. Although these catalysts can be used in the metal state, they are usually used by being attached to the surface of a carrier such as carbon, barium sulfate, silica gel, or alumina, and nickel, cobalt, copper, etc. are used as Raney catalysts. used. The amount of the catalyst used is in the range of 0.01 to 30% by weight as a metal based on the raw material nitrobenzaldoxime, usually 2 to 20% by weight when used as a Raney catalyst, and 0.05 to 30% by weight when attached to a carrier. It is in the range of 5% by weight. The reaction temperature is not particularly limited and is generally 0 to 0.
A range of 150°C, particularly 10-80°C is preferred. Further, the reaction pressure may normally be normal pressure to 10 kg/cm ² ·G. In a general embodiment of the method of the present invention, a catalyst is added to the raw material and mineral acid dissolved or suspended in a solvent, and hydrogen is introduced at a predetermined temperature until absorption stops. After the completion of the reaction, if it is in a dissolved state, the catalyst can be removed by filtration, neutralized with caustic soda, caustic potash, ammonia, triethylamine, etc., and then distilled to obtain the desired product. If the mineral salt is in a precipitated state, the desired product can be obtained by isolating and purifying the mineral salt and then neutralizing it. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 453 g (3 mol) of p-nitrobenzaldehyde is dissolved in 1350 ml of methanol. Next, while keeping the reaction temperature at 30℃, hydroxyamine hydrochloride
An aqueous solution of 241 g (3.3 mol) and 300 ml of water was added dropwise over 30 minutes. After stirring continuously at the same temperature for 2 hours, dilute with 2000 ml of water. The precipitated white crystals were filtered, washed with water and dried to obtain 480 g of p-nitrobenzaldoxime (yield 96.5%).
Melting point 128-131℃. This p-nitrobenzaldoxime 33.2g (0.2mol) and boric anhydride (18.3g (0.25mol)
mol), 1 g of 5% Pd-C catalyst and methanol
100 ml was placed in a closed glass container, and hydrogen was introduced while stirring vigorously. When the reaction temperature was maintained at 25-30°C for 13.5 hours, 22.2% of hydrogen was absorbed. Next, this reaction solution was filtered to remove the catalyst, and then concentrated under reduced pressure to remove methanol, yielding a yellow viscous liquid. 35% to this
57 g (0.5 mol) of caustic soda aqueous solution was added to neutralize the solution, and the solution separated into two layers. When the lower layer, a colorless and transparent aqueous sodium borate solution, was extracted, brown oily crude p-aminobenzylamine was obtained. This brown oily crude p-aminobenzylamine was vacuum distilled at a pressure of 5 to 6 mmHg and the distillation temperature was 129.5.
22.5 g of a fraction between 130°C and 130°C was obtained (yield 92.1%). Purity by gas chromatography was 99.93%.

[Table] Example 2 453 g (3 mol) of m-nitrobenzaldehyde was added to 50°C warm water 5, and then, while stirring,
50% hydroxyamine aqueous solution (Nichiken Kogyo product)
218 g (3.3 mol) was added dropwise. After stirring at the same temperature for 3 hours, the mixture was cooled to room temperature, filtered, washed with water, and dried to obtain 488 g of m-nitrobenzaldoxime (yield 98%). Melting point: 118-121℃ 33.2g of this m-nitrobenzaldoxime
(0.2 mol) and 70 g (0.35 mol) of 50% phosphoric acid aqueous solution,
10% Pt-C catalyst 0.3g and isobutanol 300ml
was placed in a closed glass container, and hydrogen was introduced while stirring vigorously. When the reaction temperature was maintained at 25-30°C for 18 hours, 23 hydrogen atoms were absorbed. The reaction solution is in a state where crystals have precipitated, and the crystals are passed through to form crude m-aminobenzylamine phosphate.
54.8g was obtained (yield 86.1%). 50% of this m-aminobenzylamine phosphate
Purification by recrystallization with an aqueous methanol solution yielded pure m-aminobenzylamine phosphate in the form of white scaly crystals. Melting point 210-213℃.

[Table] Next, m-aminobenzylamine phosphate was suspended in methylene chloride and liberated by blowing in ammonia gas. The precipitated ammonium phosphate was removed by filtration, and the solution was concentrated and left overnight to obtain m-aminobenzylamine in the form of crystals. Melting point 39~43℃

[Table] Example 3 33.2 g (0.2 mol) of m-nitrobenzaldoxime obtained in Example 2, Raney Nickel catalyst 3
g, boric acid 30.9 g (0.5 mol) and dioxane 150
ml into an autoclave, and while stirring vigorously, maintain the temperature at 30℃ and the hydrogen pressure at 10Kg/ ^cm2・G.
Allowed time to react. After the reaction was completed, the catalyst was removed by filtration, concentrated under reduced pressure, and then subjected to the same post-treatment as in Example 1 to obtain m-aminobenzylamine with a purity of 99.96%.
21.1g was obtained (yield 86.3%; boiling point 131-132℃/6
mmHg). Example 4 m-nitrobenzaldoxime obtained in Example 2
33.2 g (0.2 mol), 24.2 g (0.17 mol) phosphorus pentoxide, 0.5 g 5% Pd-C catalyst and 200 methanol
ml was reduced in a closed glass container under the same conditions as in Example 1. Reaction time: 10 hours, hydrogen absorption amount: 22.6
It was hot. Next, after filtering this reaction solution to remove the catalyst, 45 g (0.8 mol) of powdered caustic potassium
was carefully added to precipitate potassium phosphate. After filtering out the precipitate, distill it to obtain purity.
21.7 g of 99.4% m-aminobenzylamine was obtained (yield 88.9%; boiling point 129-130°C/5 mmHg). Example 5 Using the m-nitrobenzaldoxime obtained in Example 2 as a raw material, the same operation as in Example 1 was carried out except that tetrahydrofuran was used as the solvent and 5% Rh-C catalyst was used as the catalyst. -Aminobenzylamine was obtained in a yield of 89.2%. Example 6 16.6 g (0.1 mol) of m-nitrobenzaldoxime obtained in Example 2, 0.3 g of 5% Pd-C catalyst,
14.2 g (0.1 mol) of phosphorus pentoxide and 150 g of toluene
ml was charged into an autoclave and reacted for 7 hours while stirring vigorously while maintaining the temperature at 40-50°C and the hydrogen pressure at 3-5 kg/cm ² ·G. After the reaction was completed, the mixture was cooled and filtered to obtain 29.6 g of a mixture of precipitated crystals of crude m-aminobenzylamine phosphate and the catalyst. This rough m-
The aminobenzylamine phosphate was treated in the same manner as in Example 2 to obtain 10.2 g of a yellow oil (yield: 83.6%). Purity by gas chromatography was 98.9%. Example 7 When p-nitrobenzaldoxime was reduced in the same manner using a 5% Pd-C catalyst that had been reused four times in total in the method of Example 1, the reaction time was
It took 19 hours. The yield of p-aminobenzylamine was 92.2%. Example 8 When m-nitrobenzaldoxime was reduced in the same manner using a 5% Pd-C catalyst that was reused twice in total in the method of Example 4, the reaction time was
It took 14.5 hours. The yield of m-aminobenzylamine was 87.7%. Example 9 16.6 g (0.1 mol) of m-nitrobenzaldoxime obtained in Example 2, 0.3 g of 5% Pd-C catalyst,
6.2 g (0.1 mol) of boric acid and 50 ml of ethanol were placed in a closed glass container, and hydrogen was introduced while stirring vigorously. The reaction was carried out for 8 hours while maintaining the reaction temperature at 20 to 25°C. After the reaction was completed, the catalyst was removed by filtration, and the same post-treatment as in Example 1 was carried out to obtain a purity of 99.9.
% m-aminobenzylamine was obtained (yield
82%). Example 10 The same conditions as in Example 9 were used except that the amount of boric acid used was halved, and m-aminobenzylamine was obtained in a yield of 68.2%.

Claims (1)

[Claims] 1 General formula () (In the formula, the nitro group is at m-position or p-position) Aminobenzylamine characterized by catalytic reduction of nitrobenzaldoxime in the presence of boric acid, phosphoric acid and/or anhydride thereof. manufacturing method.