JPS61189250A - Production of aminobenzylamine - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a curing agent for epoxy resin, etc., selectively in high yield by the use of an inexpensive reducing agent under a mild condition, by reducing nitrobenzylamine as a raw material with an alkaline metallic salt of sulfide, etc. CONSTITUTION:Nitrobenzylamine shown by the formula (NO2 is in o-, m- or p-position) is reduced with an alkali metallic salt of sulfide such as Na2S, K2S, etc., or ammonium salt of sulfide such as (NH4)2S, etc., in water or a mixture of water and an organic solvent at 20-150 deg.C, and the solvent is directly recovered by vacuum distillation, to give the aimed compound. EFFECT:Since a reaction is carried out under a basic condition, an operation to isolate an acid salt of the aimed substance is not required, the aimed high- purity compound is obtained only by recovery of a solvent and liquid separation or distillation, a specific reactor is not required, a common reactor is used, so this process is industrially preferable. USE:A raw material for polyamide, polyimide, etc., or a raw material for an intermediate for agricultural chemicals and drugs.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing aminobenzylamine, and particularly provides a method that is extremely advantageous for industrial implementation.

More specifically, general formula (1) (in the formula, 2) o group is. An industrially advantageous method for producing aminobenzylamine, which comprises reducing nitrobenzylamine represented by -position (1m-position or p-position) using an alkali metal salt or ammonium salt of sulfide. .

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.

(Prior Art) Conventionally, as a method for producing aminobenzylamine, a method is typically known in which nitrobenzaldehyde or nitrobenzonitrile is used as a starting material. For example, the following method is available as a method using nitrobenzaldehyde as a starting material.

(a) Nitrobenzyl bromide is derived from nitrobenzaldehyde, firstly reacted with potassium phthalimide, and N
-(Nitrobenzyl)-phthalimide is obtained, reduced and hydrolyzed, and in this method m- and p-
-aminobenzylamine with a yield of about 20% (N, Kornblum et al., J. Am, C.
hem, Soc, 71.2137 (1949)
).

(b) This is a method in which m-nitrobenzaldehyde is reacted with phenylhydrazine to obtain a hydrazone compound, which is then catalytically reduced. By this method, m-aminobenzylamine has been obtained with a yield of 60% (A , 5iddiq
ui et al., 5ynth, Commn., 7 +71~
78 (1977)).

Km-nitrobenzaldehyde yori m--=).

Benzaldoxime is obtained, and this is subjected to high-pressure catalytic reduction using a Raney nickel catalyst, and 1m-aminobenzylamine is obtained in a yield of 52% (J, R, Gri
ff1th et al., NRL Report, 64.3
9).

On the other hand, there is the following method as a method using nitrobenzonitrile as a starting material.

) A method in which p-aminobenzonitrile derived from p-nitrobenzonitrile is reduced with lithium aluminum hydride, and p-aminobenzylamine is reduced to 37
% yield (N, C.

Brown et al., JL of Medicinal C
hem, 20°11.89 (1977)).

(yli m-Aminobenzylamine was obtained in a yield of 49% by high-pressure catalytic reduction using a m-nitropenzonityl olaneini-nokel catalyst (J, R.

Griffith et al. NRL Report, 6439
).

Another method is to use nitropenzylamine as a starting material and reduce it. for example.

(c) In-aminobenzylamine is obtained by reducing m-nitrobenzylamine with tin and hydrochloric acid (
S. Gabriel et al., Ber, 20, 2869~
2870 (1887)).

(g) O-aminobenzylamine is prepared by reducing o-nitrobenzylamine using red phosphorus and a large amount of hydriodic acid (S. Gabriel et al.).

Ber, 37, 3643-3645 (1904)).

(Problems to be Solved by the Invention) The known methods for producing aminobenzylamine as described above each have the following problems.

In other words, the method using nitrobenzaldehyde or nitrobenzonitrile as a starting material involves producing an intermediate using more than an equivalent amount of relatively expensive compounds such as potash phthalimide and phenylhydrazine, as in methods (a) and (b). However, since the target product is obtained by reducing this, these reaction steps are long.

It is not economical as it requires expense and labor to recover the by-products.

Furthermore, in the method (2), the reducing agent is expensive and difficult to handle.

Furthermore, in the methods () → and (e), a Raney nickel catalyst is used and high-pressure catalytic reduction is carried out in an autoclave, so it is clear that there are industrial disadvantages in terms of expensive equipment and low volumetric efficiency. be.

On the other hand, the method using nitrobenzylamine as a starting material (
As in the method described in (5), reduction is performed using a large amount of tin and hydrochloric acid, and the tin salt is isolated, and then this is decomposed to liberate the target product, so the target product can be reduced. The separation process from the metal compound used in the process is complicated, and care must be taken to ensure that trace amounts of metal do not remain. Further, it requires a great deal of expense and labor to make a large amount of heavy metals and waste acids non-polluting or to recover them.

As a way to improve the problems associated with these metals,
In method (g), the target product is obtained by reduction with red phosphorus and hydroiodic acid, but it is not practical because it uses a large amount of expensive hydroiodic acid and red phosphorus has a high risk of ignition. Not the point.

As described above, the known methods for producing aminobenzylamine require long steps and post-treatment (means for solving the problems). We carefully considered the method.

As a result, they discovered that aminobendiamine could be produced in high yield by using nitrobenzylamine as a raw material and reducing it using an alkali metal salt or ammonium salt of sulfide, and completed the method of the present invention. .

That is, 1 the method of the present invention is based on the general formula (1) (wherein 21
・Shut your mouth. This is a method for producing aminobenzylamine, which comprises reducing nitrobenzylamine represented by -position (1m-position or p-position) using an alkali metal salt or ammonium salt of sulfide.

Raw materials used in the method of the present invention. -Nitrobenzylamine 1 m-nitrobenzylamine or p-nitrobenzylamine.

These nitrobenzylamines are produced in high yields by reacting the corresponding nitrobenzyl chloride with ammonia or phthalimide (S, G
abriel et al. Ber, 2869 (1887) E.
L-Holmes et al., J. Chem. Soc.
1800-1821 (1925), H, L, I
ng et al., J-Chem.

Soc, 2348-2351 (1926)).

Also, as a reducing agent used in the method of the present invention.

It is an alkali metal or ammonium salt of sulfide.

Examples of alkali metal salts or ammonium sulfides include thorium sulfide and potassium sulfide.

Ammonium sulfide is mentioned. These reducing agents can be used in a small excess of the theoretical amount relative to the raw material (usually 1
, it is appropriate to use 2 to 2 times the amount.

As the solvent, water or a mixture of water and an organic solvent is used, and the organic solvents are usually methanol, ethanol, impropatol, n-butanol, methyl cellosol, ethylene glycol, propylene glycol,
Diglyme, dioxane.

Alcohols such as tetrahydrofuran, glycols,
Ethers are used, in some cases hexane, cyclohexane, benzene, toluene.

Aliphatic hydrocarbons such as ethyl acetate, butyl acetate, dichloromethane, chloroform, 1.1.2-chloroethane, aromatic hydrocarbons, and esters.

Hydrogen halides can also be used.

The mixing ratio of water and organic solvent is not particularly limited, but the weight ratio of water to organic solvent is usually 10:90 to 80:
The range is 20.

The solvent used in the liquid is not limited to 1%, but is usually used.

1 to 15 times the weight of the raw material is sufficient.

The reaction temperature is not limited to 1%, and is generally 20 to 150%.
℃ range, preferably in the range of 40 to 100'C.

In a general embodiment of the method of the present invention, the reaction is carried out by gradually adding a reducing agent to a state where the raw materials are dissolved or suspended in a solvent.

After the reaction is carried out at a predetermined temperature, the desired product can be obtained by directly recovering the solvent and the desired product by vacuum distillation, or by recovering the solvent from one reaction solution and separating the solutions.

(Function) In the method of the present invention, nitrobenzylamine is reduced in a solvent using an inexpensive reducing agent such as an alkali metal salt or an ammonium salt of a sulfide. In all cases, these reduction reactions proceed rapidly under mild conditions, allowing the desired product to be obtained selectively.

In addition, since one reaction is carried out under basic conditions, there is no need to perform operations to liberate the acid salt of the target product, such as under acidic conditions. A major feature is that it can be easily obtained.

Furthermore, since these reactions are carried out at normal pressure and reflux of the solvent or at lower temperatures, no special reaction equipment is required, and very common reaction equipment can be used, making it easy to carry out industrially. It is suitable for

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A 11 glass reactor equipped with a thermometer, reflux condenser and stirrer was charged with 152 g (1 mol) of p-nitrobenzylamine, 2Of (0.5 mol) sodium hydroxide and 400 - of water. . next.

60% sodium sulfide with stirring 260. :l'(2
mol) was added at a temperature of 40 to 50°C for 1 hour, and then stirred at a temperature of 60 to 70°C for 4 hours to complete the reaction. After cooling and standing, it was separated into two layers, so the upper oily layer was obtained.
This is vacuum distilled and the distillation temperature is 129-130℃/5
102.6 g of colorless and transparent oily p-7 minobenzylamine of wn l-19 was obtained (yield: 84%). Purity by gas chromatography was 998%. The results of elemental analysis are as follows.

Elemental analysis (C7I (as 10N2)) Example 2 The same procedure as Example 1 was carried out except that 152 g (1 mol) of m-nitrobenzylamine was used as the raw material and 450% of a 50% methanol aqueous solution was used as the solvent, and the distillation temperature was 130. ~13
Obtained 104.5 g of m-aminobenzylamine as a colorless and transparent oil at 1°C/5 vm Hf (yield 85.5%).
. Purity by gas chromatography was 99.8%. This product was crystallized when it was incubated overnight. The melting point is 4
The results of elemental analysis at 0 to 41°C are as follows.

Elemental analysis (C7I (as 10N2)) Example 3 Into a reactor similar to Example 1, 152 g (1 mol) of 0-nitrobenzylamine and 4 ml of a 50% aqueous methanol solution were added.
Charge 50d. then ammonium sulfide with stirring], 36. :M (2 mol).

Add at a temperature of 40-50°C for 1 hour. continuation,
The reaction was completed by stirring under reflux for 4 hours.

After the reaction is completed, vacuum distill the reaction solution to a distillation temperature of 91 to 9.
0-Aminobenzylamine 1 at 3°C/1-2 wAHg
00.2F was obtained (yield 82%).

The melting point was 59-61°C, and the purity by gas chromatography was 997%.

The results of elemental analysis are as follows.

Claims (1)

[Claims] 1) Represented by the general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, the nitro group is at the o-position, m-position or p-position) A method for producing aminobenzylamine, which comprises reducing nitrobenzylamine using an alkali metal salt or ammonium salt of sulfide.