JPS6396166A - Production of aromatic hydrazo compound - Google Patents

Abstract

PURPOSE:To safely obtain the titled stable high-quality compound in high yield by simple operation in a short time, by reducing an aromatic nitro compound in the presence of a hydrogen donor, e.g. formic acid, etc., in a solvent under ordinary pressure using a specific, safe, readily handleable and inexpensive catalyst. CONSTITUTION:An aromatic nitro compound expressed by formula I (X is H, Cl, OCH3 or CH3) is reduced in the presence of a hydrogenation catalyst selected from complexes expressed by formulas II, III and IV and Pd/C and a hydrogen donor selected from formic acid, acetic acid and formates in a solvent at 20-100 deg.C under ordinary pressure to afford the aimed compound expressed by formula V. Alcohols (particularly inexpensive and readily recoverable CH3OH) are preferably used as the solvent. The reaction can be safely carried out using an ordinary reaction apparatus in the same reactor at a low cost and operability is excellent. The method is economical and suitable for mass production. The equipment cost is low with hardly any deterioration of the catalyst and environmental pollution. The resultant compound is used as an intermediate for dyes or other organic synthetic chemicals.

Description

[Detailed description of the invention] Technical kite assistance The present invention relates to a method for producing aromatic hydrazo compounds.

Aromatic hydrazo compounds are very useful substances as dye intermediates or intermediates for other organic synthetic products, and are usually produced according to the following reaction formula.

Nitro compound Azoxy compound Hydrazo compound (in the above formula, X is -11.-CQ, -OCH,, -C
Conventionally, known methods for producing aromatic hydrazo compounds include the zinc powder method, glucose method, alcoholate method, alkali hydrosulfide method, and methods using paraform and formalin. In many cases, one reaction is divided into two steps, and in the first step, the aromatic nitro compound is separated as an azoxy or azo compound, and then in the second step, it is reduced to a hydrazo compound, for reasons of manufacturing process control.

This method has major drawbacks such as being cumbersome and requiring a separation device for the first stage product. Furthermore, many methods have been proposed for producing corresponding hydrazobenzenes in one step from aromatic nitro compounds.

For example, a method has been proposed in which (i) an aldehyde such as formaldehyde or paraform is added to a mixed solution consisting of an aromatic nitro compound, water, caustic alkali, and a naphthoquinoid type catalyst under a nitrogen stream to reduce it to the corresponding hydrazo compound. However, the yield of the desired hydrazo compound does not reach 85%. (Unexamined Japanese Patent Publication No. 53-63340) (i
i) Catalytic reduction of o-nitrochlorobenzene with hydrogen in the presence of a noble metal catalyst at high temperature and pressure in an aqueous alkali metal hydroxide solution with the addition of a water-immiscible aromatic solvent such as solvent naphtha, toluene, etc. te, 2,2'
- When producing dichlorohydrazobenzene, a method using an anthraquinone derivative as a cocatalyst has been proposed, but the yield of the target product is unsatisfactory at 83-85%, and chloroaniline is about 10%. This is not a very good method, considering the separation process and other side effects.

Furthermore, it requires special equipment such as a pressure-resistant reaction vessel, and has many drawbacks, such as rapid deterioration of the expensive noble metal catalyst unless high-quality 0-nitrochlorobenzene is used. (JP 54-24838) (iii) A method has been proposed in which a quinoid compound is used as a reaction promoter together with an active noble metal catalyst when aromatic nitro compounds are hydrogenated and reduced in a caustic alkaline medium. It requires special equipment such as a reaction vessel, and chloraniline is produced as a by-product.
It has major drawbacks, such as the need for separation operations. (JP 55-89253) (iv) Molecular hydrogen is added to o-nitrochlorobenzene in the presence or absence of a naphthoquinone compound and an inert organic solvent in the presence of a catalyst containing palladium or platinum and an aqueous caustic solution. During the reduction, the concentration of the aqueous caustic alkali solution was adjusted to between 3N and 15N in the first step of azoxidation.

The concentration of caustic alkali aqueous solution in the second stage reaction is 0.5N~
A method of catalytic hydrogenation between 3N and 3N has been proposed, but it requires special equipment such as a pressure-resistant reactor, and unless high-quality 0-nitrochlorobenzene is used as a raw material, the precious metal catalyst deteriorates significantly. It has the following drawbacks. (
As mentioned above, many methods have been proposed for producing hydrazo compounds from aromatic nitro compounds all at once, but these methods involve the use of expensive catalysts, the production of by-products such as anilines, and the use of pressure-resistant equipment. I don't think it's a very economical method.

Furthermore, using a platinum-based noble metal catalyst etc. in an alkaline medium,
A method has been proposed for producing the corresponding dichlorohydrazobenzene from 0-nitrochlorobenzene by adding an appropriate amount of a quinoid compound and reducing it. When using O-nitrochlorobenzene, there is a drawback that the catalyst deteriorates significantly and it is necessary to use O-nitrochlorobenzene of extremely high purity, and furthermore, chloraniline is produced as a by-product.
The separation operation is necessary and complicated.

OBJECTIVES The present invention aims to provide a new and improved method for producing aromatic hydrazo compounds that overcomes the conventional drawbacks.

As a result of intensive research to achieve the above object, the inventor of the present invention has the following general formula: h-pao.

(X is -II, -CQ, -0CH3 or -CH
, ) in a solvent, an aromatic nitro compound having P
d-CaC(i), -Pb, Pd-CaC0,, Pd
-Ba5O, and I'd-C, and a hydrogen donor selected from the group consisting of formic acid, acetic acid, and formates, at normal pressure. It has been found that the above object can be achieved by providing a method for producing an aromatic hydrazo compound having the following general formula: (X is the same as defined in the above general formula).

The reduction method according to the present invention does not require special equipment such as a pressure-resistant reaction vessel, and can be safely carried out in the same reactor from charging the aromatic nitro compound to producing the aromatic hydrazo compound using a normal reaction apparatus. It is easy to operate and has good workability. That is, compared to conventional methods, it is safe and economical, causes very little environmental pollution, and contributes to high quality, high yield, and improved productivity.

Known methods for reducing aromatic nitro compounds directly to the corresponding hydrazo compounds without isolating intermediate step products are disadvantageous in terms of equipment, production costs, productivity, environmental pollution, and safety. This method cannot be called an appropriate method, and as a result of research and study aimed at improving these drawbacks and obtaining a hydrazo compound economically and safely, an invention having the following characteristics was achieved.

A hydrogenation catalyst that is easy to handle and can withstand continuous use without fear of ignition when reducing an aromatic nitro compound and directly producing the corresponding hydrazo compound without isolating intermediate products. In the presence of methanol or other inexpensive and easily recovered solvent, formic acid (or acetic acid) and formate salts are used as hydrogen donors, and catalytic reduction is carried out in a short time using an ordinary reaction apparatus that does not require pressure. It has been found that the corresponding hydrazobenzene can be produced extremely economically with high quality and high yield.

The features of the present invention can be summarized as follows.

(b) Use an inexpensive and easily recoverable solvent such as methanol.

(b) A hydrogenation catalyst that is easy to handle and can be used continuously;
Especially Pd-CaC0,-Pb, Pd-CaC0,,
Using Pd-11aSO4 and/or Pd-C.

(c) Using inexpensive formic acid, acetic acid, and/or formate salts as a hydrogen donor.

(d) No pressure required - use of ordinary reactors.

(e) In order to efficiently decompose the hydrogen donor of formic acid and formate salts in the reaction under the above catalyst (HCOOII
→ 2 H+ Co□), only CO2 is generated and no environmental pollution problem occurs.

(f) Excess formate used in the reaction can be recovered and reused.

The hydrogenation catalyst used in the method of the present invention is Pd-Ca
CO3-Pb, Pd-CaC0,, Pd-ro aso,
, palladium-carbon (Pd-〇), etc., and Pd-CaCO, -Pb poisoned by Pb (lead) is particularly preferable,
In the case of 5% Pd-CaC0,-Pb, the amount used is 0 to the substance to be reduced (in this case, aromatic nitro compound).
．． 1%~5% (as Pd o, oos%~0.25%)
It is good to use it, preferably 0.5% to 2%.

(The amount of catalyst used may be small, but the reaction time will be extended.) The alcohol used as a solvent may be methanol, which is cheap and easy to recover, and is not particularly limited to alcohols.
Anything that dissolves the substrate is fine.

For example, hydrous alcohol may be used.

The reaction temperature is generally 20°C to 100°C, but preferably 50°C to 80°C gives good results.

Formic acid, acetic acid, formic acid salts, etc. used as hydrogen donors may be ordinary reagents or industrial ones, and it is preferable to use potassium formate, sodium formate, ammonium formate, etc., but industrially, sodium formate is advantageous. be. Also, it is better to replenish the formate recovered from the previous reaction to make up for the shortage.

Potassium formate, sodium formate, ammonium formate, etc. are used as the formate, but it is not necessary to use these alone, and a calculated amount of caustic potassium or caustic soda may be added to formic acid and used as is in the reaction.

The catalyst can be reused, and no adverse effects on quality are observed even after repeated use 10 times; however, if the reaction takes a long time, it may be advisable to add and adjust the catalyst in very small amounts.

The amount of formic acid and formate salts used as the hydrogen donor is preferably 6 to 9 mol per 1 mol of the aromatic nitro compound.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but it should be understood that the present invention is not limited thereto.

Example 1 31.0-nitrochlorobenzene in 300ml Kolben.
5g (2/10 mol), methanol 250ml 1.87%
Formic acid 15.9g (3/10 mol), 95% sodium formate 2
8.6g (4/10 mol), 5% Pd-CaC0,-P
Charge 1.6g of b, raise the temperature to reflux temperature in 30 minutes,
The reaction was continued at the same temperature for 2.5 hours. After cooling and catalyst filtration,
Most of the alcohol was recovered by distillation, and 50 ml of water was added to cool and crystallize. The obtained crystals were filtered and dried to give 24.2 g of 2,2'-dichlorohydrazobenzene.
I got it.

The melting point of the product is 83.5-86°C, the yield is 95.65
%Met. Note that 2.7% of 0-chloroaniline was produced as a by-product based on the raw material 0-nitrochlorobenzene.

Example 2 31.5 g (2/10 mol) 0-nitrochlorobenzene
.

200ml methanol 1.87% formic acid 3710mol, potassium formate 3.5/10mol, 5% Lindlar catalyst (Pd-C
1.6 g of aCO3-Pb) was charged into a 300 ml Kolben, and the reaction treatment was carried out in the same manner as in Example 1. As a result, 2,2'-dichlorohydrazobenzene having a melting point of 83.degree. 5-86.degree. C. was obtained with a yield of 97% based on the raw material 0-nitrochlorobenzene. Note that 0-chloroaniline is the raw material.

- 2.1% by-product was generated based on ditrochlorobenzene.

Example 3 0.2 mol of 0-nitrochlorobenzene, 20 mol of methanol
0ml 0.3 mol of 1.87% formic acid, 20.4 mol of ammonium formate, and 1.6 g of 5% Pd-CaC0,-Pb were charged into a reactor.

The reaction treatment was carried out in the same manner as in Example 1. As a result, the 0-
Melting point is 8 with 97% yield for nitrochlorobenzene.
2,2p-dichlorohydrazobenzene was obtained at a temperature of 3-85.5°C. Note that 0-chloroaniline is the raw material. -2.8 by-products were generated for nitrochlorobenzene.

Example 4 0.2 mol of 0-nitrochlorobenzene, 0.2 mol of 87% formic acid.
3 mol, 250 ml of methanol, 0.4 mol of fresh sodium formate added to the sodium formate recovered from Example 1, and a Pd-CaC0,-Pb catalyst.

The reaction treatment was carried out in the same manner as in Example 1. As a result, the 0-
2,2'-dichlorohydrazobenzene having a melting point of 83 to 85.5 DEG C. was obtained with a yield of 94.5% based on nitrochlorobenzene. In addition, 0-chloroaniline is the raw material 0
- for nitrochlorobenzene.

1.5% was produced as a side product.

Example 5 31.5 g (0.2 mol) of 0-nitrochlorobenzene,
Methanol 200ml 1.87% Formic acid 0.3mol, 95%
Prepared 0.4 mol of formic acid and 5% Pd-C1, Og, 60
The reaction was stirred at boiling point for a minute. The treatment was carried out in the same manner as in Example 1.

As a result, of raw materials. -8 against ditrochlorobenzene
2,2'-dichlorohydrazobenzene was obtained with a yield of 7%, and 13% of 0-chloroaniline was produced as a by-product.

Example 6 31.5 g (0.2 mol) of 0-nitrochlorobenzene was charged, and the same procedure was carried out as in the example except that 1.6 g of 5% Pd-CaC0ff was used instead of 5% Pd-CaC0,-Pb (71). The reaction treatment was carried out in the same manner as in 1.

As a result, 2,2'-dichlorohydrazobenzene was obtained with a yield of 95% and remained unreacted. - 3% of ditrochlorobenzene and 2% of 0-chloroaniline were recovered.

Example 7 30.6 g of 0-nitroanisole in 300 ml of Kolben
(0.2 mol), methanol 200ml 1.87% formic acid 0
．． 3 mol, sodium formate 0.4 mol, 5% Pd-CaC0
, -Pb (1.6 g) was charged, and the mixture was reacted under reflux for 3.5 hours. The rest of the process was carried out in the same manner as in Example 1.

As a result, a yield of 94% and a melting point of 94-101°C were obtained.
2'-dimethoxyhydrazobenzene was obtained.

Note that 0-anisidine was produced as a by-product.

Length - As stated above, according to the method of the present invention, the following effects can be obtained.

(a) 7niline derivatives, such as chlorani IJ'
) etc., and the produced hydrazo compound is of high quality.

(b) Since the reaction time is short, it can be produced in a short time and is suitable for mass production.

(c) Since the intermediate step product, the azoxy-azo compound, is not isolated, the operation is simple and equipment can be omitted.

(d) Since a safe, easy-to-handle, and stable catalyst is used, operation is safe, and catalyst deterioration is small, so there is little impact on production costs.

(e) Since a pressure vessel is not used, a very ordinary reaction apparatus is used without using a special reaction apparatus, so the equipment cost is low and the operation is simple.

(f) Since the catalyst used in the present invention has little catalyst deterioration, it is not necessary to use a particularly high-quality aromatic nitro compound, and even if a common industrial product is used, it can be used repeatedly 10 times or more.

(g) Since the solvent is recovered and reused, there will be no problem of environmental pollution due to wastewater or waste.

(h) Efficiently decomposes formic acids used as hydrogen donors (
Since the reduction is performed by converting 1+cOOH→211+Co,), only CO2 is generated, and there is no problem of environmental pollution such as wastewater treatment.

Claims (1)

[Claims] 1. An aromatic nitro compound having the following general formula, ▲Mathematical formula, chemical formula, table, etc.▼ (X represents -H, -Cl, -OCH_3 or -CH_3) in a solvent. In Pd-
CaCO_3-Pb, Pd-CaCO_3, Pd-Ba
reducing the following at normal pressure in the presence of a hydrogenation catalyst selected from the group consisting of SO_4 and Pd-C and a hydrogen donor selected from the group consisting of formic acid, acetic acid and formate salts. A method for producing an aromatic hydrazo compound having the general formula, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (X is the same as the definition of the general formula above).