JP2000290235A - Production of 3-nitro-2-methylbenzoic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically obtain 3-nitor-2-methylbenzoic acid in a high conversion and high selectivity by oxidizing a nitorxylene with an oxygen-containing gas in the presence of a cobalt catalyst or the like in a lower fatty acid solvent without causing any corrosion of the equipment. SOLUTION: This compound of formula II is obtained by oxidizing (A) 3- nitor-o-xylene of formula I with (B) an oxygen-containing gas in the presence of (C) 0.03-0.2 molar times of a cobalt catalyst based on the component A and (D) 0.5-3.0 molar times of an initiator based on the component A, in the absence of (E) a corrosive halogen compound, in (F) 0.5-5 wt. times of a lower fatty acid solvent based on the component A. The component C is e.g. a lower fatty acid cobalt salt, naphthenic acid cobalt salt, acetylacetate. The component D is preferably 2-butanone, 4-methyl-2-pentanone, acetaldehyde, paraldehyde or the like. The component F is e.g. acetic acid, propionic acid, butyric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing 3-nitro-2-methylbenzoic acid, and its object is to convert 3-nitro-o-xylene and selectivity for 3-nitro-2-methylbenzoic acid. For producing 3-nitro-2-methylbenzoic acid with high production efficiency, economical production efficiency and high production efficiency, and without using a halogen that corrodes the production equipment during production Is to provide.

[0002]

2. Description of the Related Art In recent years, 3-nitro-2-methylbenzoic acid has been increasingly useful as a raw material intermediate for pharmaceuticals and agricultural chemicals. This 3-nitro-2-methylbenzoic acid has been conventionally produced by oxidizing 3-nitro-o-xylene. As a specific production method, an oxidation method using nitric acid (US Pat. No. 4,065,477) Gazette)
Or an oxidation method using permanganic acid (Zhurnal. Obschche
i.Khimii. (Kulic, J .; Adamek, M.) 60 (10) 2370, (1998)).

However, the above-mentioned conventional method for producing 3-nitro-2-methylbenzoic acid has the following problems. First, the method described above,
The method of oxidizing nitro-o-xylene to obtain 3-nitro-2-methylbenzoic acid has a low conversion of 3-nitro-o-xylene and a high selectivity of 3-nitro-2-methylbenzoic acid. for even lower, 6-nitro-2-methylbenzoic acid and by-products such as dinitro product ends up produced in large amounts, also harmful NO _x gases in the reaction has a problem that a large amount of generated . One method, i.e., the method of oxidizing 3-nitro-o-xylene with permanganic acid to obtain 3-nitro-2-methylbenzoic acid, comprises 3-nitro-o-xylene.
Although the conversion of xylene is high, the selectivity of 3-nitro-2-methylbenzoic acid is low, so that 6-nitro-2
There is also a problem that a large amount of by-products such as -methylbenzoic acid and 3-nitrophthalic acid are generated, and a large amount of permanganate is required.

As a method for highly selectively obtaining 3-nitro-2-methylbenzoic acid, a method of oxidizing with an oxygen-containing gas using a heavy metal catalyst and a halogen compound as a reaction accelerator in a lower fatty acid solvent is a special method. Kaihei 10-2876
No. 27 and Zhurnal.Fizicheskoi.Khimii. (KAChervins
kii, VI Kovalev) 1969, 43 (8) 2062.

[0005] The method for producing 3-nitro-2-methylbenzoic acid disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-287627 is, more specifically, a method in which 3-nitro-o-xylene is dissolved in a lower aliphatic carboxylic acid solvent. Alternatively, in a mixed solvent of a lower aliphatic carboxylic acid and an organic solvent, oxidation with oxygen or an oxygen-containing gas in the presence of a heavy metal catalyst and a reaction accelerator, and if necessary, a reaction accelerator, to give 3-nitro- This is a method for obtaining 2-methylbenzoic acid. In this production method, acetic acid, propionic acid, butyric acid and the like are used as lower aliphatic carboxylic acids, and bromides and hydroxides of heavy metals such as cobalt, manganese, cerium, and copper (for example, cobalt acetate) are used as heavy metal catalysts. Are bromine compounds such as bromine, hydrogen bromide, cobalt bromide, ammonium bromide, and alkali metal bromine compounds, and halogen compounds such as iodine compounds as reaction accelerators, and aldehydes and ketones as reaction accelerators. Are exemplified. Although this production method has an effect that the selectivity of 3-nitro-2-methylbenzoic acid is higher than that of the conventional production method, this method also has the following problems.

That is, the above-mentioned method has a high conversion, and the selectivity of 3-nitro-2-methylbenzoic acid is slightly higher than that of the above-mentioned method.
Since it is as low as 6%, 6-nitro-2-methylbenzoic acid and 3
-The problem of large amounts of by-products, such as nitrophthalic acid, remains. In addition, in this method, the presence of a halogen compound having high corrosiveness to metals, such as a bromide compound such as sodium bromide or ammonium bromide, as a reaction accelerator is an essential condition. May corrode. Therefore, it is necessary to use expensive equipment made of a material having corrosion resistance in order to prevent corrosion, and there is also a problem that a halogen compound remains in the product. Furthermore, a large amount of solvent requires a large amount of energy to recover the solvent after the reaction, a low substrate concentration requires a low production efficiency and a large-capacity device, and a large amount of a catalyst requires There is also a problem that it takes time and effort to recover the processing. Therefore, when 3-nitro-2-methylbenzoic acid is produced commercially by this method, the production cost increases due to the increase in mechanical costs, product refining costs, waste disposal costs, and the like, resulting in high production costs. The method was not suitable for commercial production.

[0007]

That is, it is generally said that it is difficult to oxidize methylbenzenes having a nitro group with an oxygen-containing gas.
A method has been proposed in which a halogen compound for accelerating the reaction is added or oxidation is performed using a large amount of a catalyst. However, since this method has various problems as described above,
In a method for producing 3-nitro-2-methylbenzoic acid by oxidizing nitro-o-xylene, the conversion and selectivity are high, and the generation of by-products can be suppressed.
It has been desired to create a method for producing 3-nitro-2-methylbenzoic acid which is economical with high production efficiency and which does not corrode the production equipment during production.

Accordingly, the present inventors have developed a method for producing 3-nitro-2-methylbenzoic acid economically without causing corrosion of the production equipment because of high conversion and selectivity and excellent production efficiency. As a result of continuing intensive research on possible methods, the use of a small amount of solvent and keeping the relative concentration of the catalyst high with respect to the substrate even with a small amount of the catalyst enables the high concentration of the compound even without a highly corrosive halogen compound such as a bromine compound. The reaction proceeds at a high conversion and a high selectivity, and does not cause corrosion of the production equipment.
Finding that methylbenzoic acid can be produced,
The present invention has been completed.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and the invention according to claim 1 relates to a method for preparing 3-nitro-o-xylene in a lower fatty acid solvent. Oxidizing with an oxygen-containing gas in the absence of a corrosive halogen compound and in the presence of a cobalt catalyst and an initiator to obtain 3-nitro-2-methylbenzoic acid. The present invention relates to a method for producing methylbenzoic acid.

The invention according to claim 2 is characterized in that at least one of acetic acid, propionic acid and butyric acid is used as the lower fatty acid solvent. Claim 3 relates to a method for producing benzoic acid.
3. The method according to claim 1, wherein the lower fatty acid solvent is used in an amount of 0.5 times by weight or more and less than 5 times by weight of 3-nitro-o-xylene.
The present invention relates to a method for producing nitro-2-methylbenzoic acid.

The invention according to claim 4 is characterized in that at least one of cobalt lower fatty acid salt, naphthenate and acetylacetonate is used as the cobalt catalyst. The invention according to claim 5 relates to a method for producing 3-nitro-2-methylbenzoic acid, wherein the amount of the cobalt catalyst used is at least 0.03 mol times and at least 0.2 mol of 3-nitro-o-xylene. The 3-nitro-2- according to any one of claims 1 to 4, which is not more than twice.
The present invention relates to a method for producing methylbenzoic acid.

Further, the invention according to claim 6 is characterized in that at least one of 2-butanone, 4-methyl-2-pentanone, acetaldehyde and paraaldehyde is used as the initiator. 6. The method according to claim 7, wherein the initiator is used in an amount of 3 to 3.
The method for producing 3-nitro-2-methylbenzoic acid according to any one of claims 1 to 6, wherein the molar ratio is 0.5 mol times or more and 3.0 mol times or less with respect to -nitro-o-xylene.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The process for producing 3-nitro-2-methylbenzoic acid according to the present invention uses 3-nitro-o-xylene as a starting material, and is used in a lower fatty acid solvent in a corrosive halogen compound. And in the presence of a cobalt catalyst and an initiator in the absence of
This is a method of oxidizing 3-nitro-o-xylene with an oxygen-containing gas to obtain 3-nitro-2-methylbenzoic acid.

Embedded image

The lower fatty acid solvent used is not particularly limited, and examples thereof include acetic acid, propionic acid, and butyric acid. It is also possible to use two or more of these lower fatty acid solvents. Particularly, acetic acid is preferably used because it is inexpensive and excellent in handling.

The amount of the solvent used is not particularly limited, either.
With respect to 3-nitro-o-xylene, which is a starting material, 0.1% is used.
It is preferably at least 5 times by weight and less than 5 times by weight, preferably 0.5 to 2 times by weight. If the amount is less than 0.5 times by weight, the reaction rate decreases and the selectivity of 3-nitro-2-methylbenzoic acid also decreases. On the other hand, if the amount is more than 5 times by weight, the selectivity slightly increases. However, because a larger reaction vessel is required, the efficiency of the kettle is poor, the conversion is reduced, and the productivity is deteriorated. In either case, it is not preferable.

The cobalt catalyst used is not particularly limited as long as it can be dissolved in the lower fatty acid solvent during the reaction. Specifically, lower fatty acid salts of cobalt such as cobalt acetate, naphthenate salts of cobalt, and acetylacetonate of cobalt can be exemplified, and two or more kinds can be used. Particularly, cobalt acetate is preferably used because it is economical.

The amount of the cobalt catalyst to be used is not particularly limited either, but it is 0.03 to 0.2 mol times, preferably 0.06 to 0.2 times the 3-nitro-o-xylene used as the starting material.
It is preferable to set it as 0.1 mol times. If the molar ratio is less than 0.03 mol, the selectivity is lowered and the reaction rate is low. Even if the molar ratio exceeds 0.2 mol, the reaction speed does not change, which is economically disadvantageous. This is also undesirable.

[0018] Initiators are used to accelerate the reaction.
Organic strong acids and the like can be used. It is also possible to use two or more types. In particular, 2-butanone, 4-
Methyl-2-pentanone, acetaldehyde and paraaldehyde are preferably used from the viewpoint of contamination of the reaction system with impurities and the corrosion resistance of the apparatus. Among them, 2-butanone is most preferably used from the viewpoint of toxicity and handling.

The amount of the initiator used is not particularly limited either, but it is 0.5 to 3.0 mole times, preferably 0.5 to 1. 0 times the molar amount of 3-nitro-o-xylene as a starting material.
It is preferable to make the molar ratio 5 times. If the amount is less than 0.5 mol times, the effect of the initiator will not be sufficiently exhibited, and the reaction rate will decrease. If the amount is more than 3.0 mol times, the selectivity of 3-nitro-2-methylbenzoic acid will increase. In any case, which is not preferable.

Using the lower fatty acid as a solvent and oxidizing 3-nitro-o-xylene with an oxygen-containing gas in the presence of a cobalt catalyst and an initiator to obtain 3-nitro-2-methylbenzoic acid Can be.
In the present invention, the oxidation reaction is performed in the absence of a bromide such as sodium bromide or ammonium bromide or a halogen compound such as iodide. This is because halogen compounds, which are reaction accelerators, are highly corrosive to metals, so expensive equipment made of corrosion-resistant materials must be used to prevent corrosion of manufacturing equipment, and oxidation reactions in the presence of halogen compounds are required. Is carried out, the halogen compound remains in the product. Moreover, in the present invention, the oxidation reaction proceeds at a sufficiently high conversion and selectivity even in the absence of the halogen compound, so that it is not necessary to use the halogen compound as a reaction accelerator.

As the oxidizing agent for the oxidation reaction, any oxygen-containing gas can be used without any particular limitation, but air is preferably used from the viewpoint of safety during the reaction and economy.

The method of introducing the oxygen-containing gas is not particularly limited, but the method of blowing into the reaction solution is most preferable from the viewpoint of dispersion efficiency. The reaction pressure during the introduction is 1 to 20 atm,
Desirably, the pressure is 1 to 10 atm. The oxidation reaction proceeds even at normal pressure, but a sufficient reaction rate cannot be obtained,
If the pressure exceeds 0 atm, there is no particular effect, and the cost of the apparatus is too high, and in either case, it is not preferable.

The amount of the oxygen-containing gas introduced is not particularly limited. However, considering the amount of oxygen consumed in the reaction, it is preferable to set the oxygen concentration of the exhaust gas from the reaction vessel to 9% or less. This is because if the oxygen concentration of the exhaust gas exceeds 9%, the gas phase of the reactor may form an explosive mixed gas, which is not preferable in terms of safety. Specifically, it is preferable to introduce 0.5 to 1 L / min based on 1 mol of 3-nitro-o-xylene.

The reaction temperature is not particularly limited, and may be appropriately set depending on the type of gas used. For example, when air is used as the oxygen-containing gas,
More preferably, the temperature is set to 80 to 120 ° C. this is,
At a low temperature lower than 60 ° C., the reaction rate becomes too slow. On the other hand, at a high temperature exceeding 150 ° C., the reaction rate is increased but the selectivity is greatly reduced, and the productivity is lowered.

After performing the oxidation reaction according to the above method,
The method for obtaining the target product, 3-nitro-2-methylbenzoic acid, from the reaction solution is not particularly limited, and may be performed according to a conventional method. For example, the following method can be exemplified. First, the reaction solution is concentrated and then extracted with an extraction solvent.
The extract is washed with water and then extracted again with alkali. Next, the alkali extract is washed again, then acidified, filtered, and finally dried to obtain 3-nitro-2-methylbenzoic acid.

In addition to the above method, the following method can be exemplified as a simplified method. First, the reaction solution is concentrated, and then water is injected to cause crystallization. Next, the slurry liquid is filtered, washed with a small amount of acetic acid, and finally washed with water and dried to obtain 3-nitro-2-methylbenzoic acid.

The method for producing 3-nitro-2-methylbenzoic acid according to the present invention is as described above. As will be apparent from the examples described later, it is economical at high conversion and high selectivity.
-Nitro-2-methylbenzoic acid can be produced.

[0028]

EXAMPLES Hereinafter, the method for producing 3-nitro-2-methylbenzoic acid according to the present invention will be described in detail with reference to examples.
However, the present invention is not limited at all by the following examples.

(Example 1) In a 1 L autoclave equipped with a reflux condenser, a thermometer, an air inlet, and a stirrer, 605 g of acetic acid as a reaction solvent and 25 g (0.1 mol) of cobalt acetate tetrahydrate as a catalyst were used. , 2 as an initiator
- butanone 72 g (1 mol), 3-nitro -o- sequentially charged xylene 151g (1 mole) and pressurized to 8 kg / cm ^2, air was introduced at a rate of 1L / min. Thereafter, an oxidation reaction was carried out while heating to 80 ° C. until oxygen absorption disappeared.

Examples 2 to 7 The reaction was carried out in the same manner as in Example 1 except that the amount of acetic acid and the amount of catalyst were changed. Specific numerical values are shown in Table 1 below.

Examples 8 to 12 The reaction was carried out in the same manner as in Example 1 except that the amount of 2-butanone was changed. Specific numerical values are shown in Table 1 below.

(Examples 13 to 17) Reaction temperature, amount of acetic acid,
The reaction was carried out in the same manner as in Example 1 except that the amount of the catalyst was changed. Specific numerical values are shown in Table 1 below.

(Example 18) The reaction pressure was 5 kg / cm
^{2. The} reaction was carried out in the same manner as in Example 7, except that the reaction temperature was changed to 85 ° C.

(Examples 19 and 20) The reaction solvent was changed to propionic acid or butyric acid, and the reaction pressure was further increased to 5 kg / cm ² ,
The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was changed to 85 ° C.

(Examples 21 to 22) The reaction pressure was 5 kg /
cm ^2, the catalyst instead of the naphthenate or acetylacetonate of cobalt, the reaction was performed in the same manner as in Example 1 except that further changing the amount of acetic acid in 303 g.

(Examples 23 to 25) The reaction pressure was 5 kg /
The reaction was carried out in the same manner as in Example 1 except that cm ² and the initiator were changed to 4-methyl-2-pentanone, acetaldehyde or paraaldehyde, and the amount of acetic acid was further changed to 303 g.

(Example 26) The scale-up of Example 18 was performed using a 100 L glass-lined reaction tank. That is, acetic acid 22.75 kg, cobalt acetate tetrahydrate 2.5 kg (10 mol), 2-butanone 10.85 k
g (150 mol), 3-nitro-o-xylene 22.7
Using 5 kg (150 mol), air was introduced at 8 M ³ / h, and then an oxidation reaction was performed at a reaction temperature of 85 ° C.

(Comparative Example 1) 484 g of acetic acid, 20 g (0.8 mol) of cobalt acetate tetrahydrate, 8 g of ammonium bromide (0 mol) were placed in a 1 L flask equipped with a reflux condenser, a thermometer, an air inlet, and a stirrer. 0.08 mol), 121 g (0.8 mol) of 3-nitro-o-xylene, and 1 L /
Air was introduced at a rate of min. Thereafter, an oxidation reaction was performed while heating to 85 ° C. until oxygen absorption disappeared.

(Comparative Example 2) 484 g of acetic acid, 20 g (0.8 mol) of cobalt acetate tetrahydrate, 2.8 g of sodium bromide were placed in a 1 L flask equipped with a reflux condenser, a thermometer, an air inlet, and a stirrer. (0.027 mol), 3-nitro-o-
Xylene 121 g (0.8 mol) is charged and 5 kg / c
The pressure was increased to m ² and air was introduced at a rate of 1 L / min. Thereafter, an oxidation reaction was performed while heating to 120 ° C. until oxygen absorption disappeared.

Comparative Example 3 A reaction was conducted in the same manner as in Comparative Example 2 except that 2-butanone was added.

After the completion of the reactions in Examples 1 to 26 and Comparative Examples 1 to 3, the obtained reaction solutions were analyzed by high performance liquid chromatography, and the conversion of 3-nitro-o-xylene, 3-nitro- The selectivity and the production rate of -2-methylbenzoic acid were determined. The results are shown in Tables 1 and 2. In the table,
The amount of the solvent is a weight multiple of the weight of 3-nitro-o-xylene, and the amount of the catalyst, the amount of 2-butanone and the amount of the bromide are shown in mol% based on the amount of 3-nitro-o-xylene. The production efficiency is the quantity (g) of the target product / the weight (kg) x time
This is the value calculated by (h).

[Table 1]

[Table 2]

From the results of Tables 1 and 2, it can be seen that when 3-nitro-2-methylbenzoic acid is produced by the method according to the present invention, both the conversion and the selectivity are relatively high, and the production efficiency is high. . On the other hand, in Comparative Examples 1 to 3, both the conversion and the selectivity were low, and it was found that the production efficiency was extremely low. Moreover, in the present invention, since the highly corrosive halogen compound used in the comparative example is not used, no halogen is mixed in the target product, and no halogen is contained in the waste. Does not corrode.

[0043]

As described in detail above, the invention according to claim 1 is characterized in that 3-nitro-o-xylene is dissolved in a lower fatty acid solvent.
Oxidizing with an oxygen-containing gas in the absence of a corrosive halogen compound and in the presence of a cobalt catalyst and an initiator to obtain 3-nitro-2-methylbenzoic acid. Since the present invention relates to a method for producing methylbenzoic acid, the following effects are obtained.

[0044] That is, 3 since the conversion of nitro -o- xylene and selectivity of 3-nitro-2-methylbenzoic acid is high, it is possible to suppress the formation of by-products, harmful NO _x in the reaction Gas generation can be prevented. Moreover, since the production efficiency is high, 3-nitro-
2-methylbenzoic acid can be produced. In addition, since 3-nitro-2-methylbenzoic acid can be efficiently produced by eliminating the presence of a halogen compound having a corrosive property to a metal, the production apparatus is corroded and the halogen compound remains in the product. Since there is no need to use a special corrosion-resistant material for manufacturing equipment, manufacturing costs can be reduced. Further, since the waste does not contain halogen, it is environmentally friendly and the burden of waste treatment can be reduced.

The invention according to claim 2 is characterized in that at least one of acetic acid, propionic acid and butyric acid is used as the lower fatty acid solvent. Claim 3 relates to a method for producing benzoic acid.
3. The method according to claim 1, wherein the lower fatty acid solvent is used in an amount of 0.5 times by weight or more and less than 5 times by weight of 3-nitro-o-xylene.
Since the present invention relates to a method for producing nitro-2-methylbenzoic acid, the following effects are obtained. That is, by reducing the amount of the reaction solvent and improving the selectivity of 3-nitro-2-methylbenzoic acid, the production amount of the target substance in the reaction vessel is greatly increased, and the energy required for taking out the target substance is reduced. In addition, since the production method can be simplified, the production cost can be significantly reduced.

The invention according to claim 4 is characterized in that at least one of cobalt lower fatty acid salt, naphthenate and acetylacetonate is used as the cobalt catalyst. The invention according to claim 5 relates to a method for producing 3-nitro-2-methylbenzoic acid, wherein the amount of the cobalt catalyst used is at least 0.03 mol times and at least 0.2 mol of 3-nitro-o-xylene. The 3-nitro-2- according to any one of claims 1 to 4, which is not more than twice.
Since the present invention relates to a method for producing methylbenzoic acid, the amount of the catalyst used can be reduced, and the time and effort for processing and recovering the catalyst can be reduced.

The invention according to claim 6 is characterized in that at least one of 2-butanone, 4-methyl-2-pentanone, acetaldehyde and paraaldehyde is used as the initiator. 3 in 5
Regarding the method for producing -nitro-2-methylbenzoic acid, the invention according to claim 7, wherein the amount of the initiator used is 3-
0.5 mol times or more of nitro-o-xylene;
The method according to any one of claims 1 to 6, wherein the molar ratio is 0 mol or less, and the oxidation reaction is performed while maintaining high conversion and high selectivity. Can be promoted.

In the method for producing 3-nitro-2-methylbenzoic acid according to the present invention, since various effects as described above are exerted, the production efficiency can be increased and the production cost can be reduced. -Nitro-2-methylbenzoic acid can be produced industrially and more economically.

Claims (7)

[Claims] 1. A 3-nitro-formula represented by the following formula 1
O-xylene is oxidized with an oxygen-containing gas in a lower fatty acid solvent in the absence of a corrosive halogen compound and in the presence of a cobalt catalyst and an initiator, and is expressed by the following formula 2 A method for producing 3-nitro-2-methylbenzoic acid, comprising obtaining nitro-2-methylbenzoic acid. Embedded image Embedded image 2. The method for producing 3-nitro-2-methylbenzoic acid according to claim 1, wherein one or more of acetic acid, propionic acid, and butyric acid are used as the lower fatty acid solvent. 3. The method according to claim 1, wherein the lower fatty acid solvent is used in an amount of 0.5 times by weight or more and less than 5 times by weight of 3-nitro-o-xylene.
A method for producing nitro-2-methylbenzoic acid. 4. The 3-nitro-2-catalyst according to claim 1, wherein at least one of cobalt lower fatty acid salt, naphthenate and acetylacetonate is used as the cobalt catalyst. A method for producing methylbenzoic acid. 5. The method according to claim 1, wherein the amount of the cobalt catalyst used is not less than 0.03 mol times and not more than 0.2 mol times based on 3-nitro-o-xylene. A method for producing -nitro-2-methylbenzoic acid. 6. The initiator includes 2-butanone, 4-methyl-2-pentanone, acetaldehyde,
The method for producing 3-nitro-2-methylbenzoic acid according to any one of claims 1 to 5, wherein at least one of paraaldehydes is used. 7. The method according to claim 1, wherein the amount of the initiator used is 0.5 mol times or more and 3.0 mol times or less with respect to 3-nitro-o-xylene. A method for producing -nitro-2-methylbenzoic acid.