JPH06172260A - Production of naphthalenecarboxylic acid - Google Patents

Abstract

PURPOSE:To produce naphthalenecarboxylic acid in the presence of a catalyst containing cobalt, manganese and bromine respectively in a specified concentration in a high yield while reducing the amount of the solvent to be used in comparison with conventional methods. CONSTITUTION:In the production of naphthalenecarboxylic acid by oxidation of methylnaphthalene in the presence of a lower aliphatic carboxylic acid (especially preferably acetic acid) and a catalyst, the lower aliphatic carboxylic acid is used in an amount of <38 pts.wt. and >=5 pts.wt., especially 10 to 20 pts.wt. based on 1 pts.wt. naphthalenecarboxylic acid. In the catalyst containing cobalt, manganese and bromine, Co, Mn and Br are used respectively in amounts satisfying the relation: Co+Mn=0.05 to 1.0, preferably 0.16 to 0.56, Mn/Co=0.5 to 100, preferably 1 to 60 based on the lower aliphatic carboxylic acid on weight percentage base, Br>=0.001/Mn and preferably Br>=0.0075/Mn.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method capable of producing naphthalenecarboxylic acid in high yield.

[0002]

BACKGROUND OF THE INVENTION Naphthalenecarboxylic acids, such as naphthoic acid, are used as photographic chemicals, dyes and pigments, and naphthalenedicarboxylic acids, especially 2,6-naphthalenedicarboxylic acid, are obtained by reacting a glycol with polyethylene. Since it is superior in heat resistance and mechanical properties to terephthalate, it is used in applications such as films and tire cords. Furthermore, naphthalene tricarboxylic acid and naphthalene tetracarboxylic acid are regarded as promising raw materials for highly functional resins and the like.

Conventionally, many methods for producing naphthalenecarboxylic acid from methylnaphthalene have been proposed. For example, as a method for producing 2,6-naphthalenedicarboxylic acid, 2,6-dimethylnaphthalene is oxidized with molecular oxygen in the presence of an oxidation catalyst containing cobalt, manganese, and bromine in an acetic acid solvent to give 2,6 -Methods for producing naphthalenedicarboxylic acid (Japanese Patent Publication No. 48-43893, Japanese Patent Publication No. 56-3337, etc.) are known.

[0004]

However, in these methods, unless a large amount of solvent in the reaction system is used, that is, about 38 times by weight or more with respect to methylnaphthalene, oxidation intermediates such as aldehydes remain, There is a drawback that naphthalenecarboxylic acid cannot be obtained in high yield. Further, in order to improve this drawback, a method of using an aromatic compound such as dichlorobenzene as a solvent (JP-A-64-3
No. 148, etc.) is also known, but even in this method, the productivity per solvent unit is not sufficient, which is a disadvantage as an industrial production method.

Therefore, a method for producing naphthalenecarboxylic acid at low cost and in high yield has been desired.

[0006]

Under such circumstances, the present inventors have conducted diligent research and as a result, if cobalt, manganese, and bromine at specific concentrations were used as catalysts, a smaller amount of solvent than before was used. The present invention has been completed by finding that naphthalenecarboxylic acid can be produced in a high yield.

That is, the present invention provides a method for producing naphthalenecarboxylic acid by oxidizing methylnaphthalene in the presence of a lower aliphatic carboxylic acid and a catalyst, wherein (1) 1 part by weight of methylnaphthalene is used as the lower aliphatic Carboxylic acid 5
(2) a catalyst containing cobalt, manganese, and bromine as a catalyst with respect to a lower aliphatic carboxylic acid represented by the following formulas A to C: A: 0.05 ≦ Co + Mn ≦ 1.0 B : 0.5 ≦ Mn / Co ≦ 100 C: Br ≧ 0.001 / Mn (wherein Co, Mn, and Br represent the weight percentages of cobalt, manganese, and bromine atoms relative to the lower aliphatic carboxylic acid, respectively) The present invention provides a method for producing a naphthalenecarboxylic acid, which is characterized in that it is used in a filling amount.

Methylnaphthalene used in the present invention is
A naphthalene ring having 1 to 4 methyl groups,
For example, 1-methylnaphthalene, 2-methylnaphthalene,
1,2-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene, 1,6-dimethylnaphthalene, 1,7-dimethylnaphthalene, 1,8-dimethylnaphthalene, 2 ，
3-dimethylnaphthalene, 2,6-dimethylnaphthalene, 2,7-dimethylnaphthalene, 1,2,6-trimethylnaphthalene, 1,2,7-trimethylnaphthalene,
1,4,5-trimethylnaphthalene, 2,3,7-trimethylnaphthalene, 1,2,5,6-tetramethylnaphthalene, 1,4,5,8-tetramethylnaphthalene,
2,3,6,7-tetramethylnaphthalene and the like can be mentioned.

Examples of the lower aliphatic carboxylic acid include acetic acid, propionic acid and butyric acid.
Acetic acid is particularly preferable. The amount of lower aliphatic carboxylic acid used is 5 parts by weight or more and less than 38 parts by weight, preferably 5 to 30 parts by weight, and more preferably 10 to 20 parts by weight with respect to 1 part by weight of methylnaphthalene as a raw material.

The catalyst used in the present invention may be one containing cobalt, manganese or bromine, which has been conventionally used as an oxidation catalyst, and is preferably one which is soluble in acetic acid. Among these, examples of the cobalt compound and the manganese compound include salts of cobalt and manganese with aliphatic carboxylic acids having 1 to 4 carbon atoms such as formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, and maleic acid; Salts of cyclic carboxylic acids; salts of aromatic carboxylic acids such as benzoic acid, terephthalic acid, naphthoic acid and naphthalene dicarboxylic acid; inorganic compounds such as hydroxides, oxides and bromides. Of these, salts of aliphatic carboxylic acids are preferable, and cobalt acetate and manganese acetate are particularly preferable. As these cobalt salts or manganese salts, either anhydrous salts or hydrous salts can be used. Further, as the bromine compound, for example, hydrobromic acid, ammonium bromide, sodium bromide, potassium bromide, cobalt bromide, manganese bromide,
Examples thereof include bromoacetic acid, and ammonium bromide is particularly preferable.

In the present invention, these catalysts are used in an amount satisfying the following formulas A to C. A: 0.05 ≦ Co + Mn ≦ 1.0, preferably 0.1
6 ≦ Co + Mn ≦ 0.56 B: 0.5 ≦ Mn / Co ≦ 100, preferably 1 ≦ Mn
/ Co ≦ 60 C: Br ≧ 0.001 / Mn, preferably Br ≧ 0.0
075 / Mn

Further, it is particularly preferable that the amounts of cobalt, manganese, and bromine satisfy the following formulas and the above formulas A to C, respectively. 0.01 ≦ Co ≦ 0.3 0.05 ≦ Mn ≦ 0.7 0.01 ≦ Br ≦ 0.15

If the amounts of cobalt and manganese used are not within the range satisfying the above formula, naphthalenecarboxylic acid cannot be obtained in high yield. Also, bromine acts as a reaction initiator, but if the amount is less than the amount satisfying the above formula,
The reaction does not start well and the yield is lowered. If the amount is too large, byproducts increase and the product becomes colored.

In the present invention, molecular oxygen is used to oxidize methylnaphthalene. As the molecular oxygen, for example, pure oxygen; a mixed gas of oxygen, an inert gas such as nitrogen, helium, and argon, and the like can be used, and air is particularly preferable from the viewpoint of ease of use.

The reaction is carried out by blowing an oxygen-containing gas into the reaction mixture and can be carried out batchwise or continuously. At this time, the reaction temperature is 160 to 22.
It is preferably 0 ° C, particularly 180 to 200 ° C. 16
When the temperature is lower than 0 ° C, the yield of naphthalenecarboxylic acid is drastically reduced, and when the temperature is higher than 220 ° C, trimellitic acid or the like is generated due to the cleavage of the naphthalene ring, and the combustion loss of the aliphatic carboxylic acid as a solvent is increased, which is preferable. Absent. The reaction pressure is not particularly limited as long as it is equal to or higher than the vapor pressure of the reaction mixture, but the oxygen partial pressure is ^{2 to} 10 kg / cm ² , particularly 2 to
It is preferably 6 kg / cm ² .

[0016]

EXAMPLES Next, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

Example 1 In a titanium autoclave having a gas blow-in pipe and a gas discharge port at the top and equipped with a stirrer, 4 g of 2,6-dimethylnaphthalene, 150 g of glacial acetic acid, and cobalt acetate tetrahydrate were added.
5 g, manganese acetate tetrahydrate 1.8 g and ammonium bromide 0.24 g were added, and the temperature was 200 ° C. and the pressure was 30 kg / cm ^2.
While maintaining the temperature at above, while stirring, compressed air was blown from the gas introduction tube at a rate of about 1 l / min to cause a reaction for 40 minutes. The reaction product was filtered, washed with hot acetic acid, and then separated into a solid content and an acetic acid-soluble content. The obtained solid and the product in acetic acid were used as methyl ester, and gas chromatographic analysis revealed that
-The yield of naphthalenedicarboxylic acid was 93 mol%.

Examples 2 to 4 and Comparative Example 1 2,6-naphthalenedicarboxylic acid was produced in the same manner as in Example 1 except that the charged amount of 2,6-dimethylnaphthalene was changed as shown in Table 1. The yield of the obtained 2,6-naphthalenedicarboxylic acid is shown in Table 1.

[0019]

[Table 1]

Examples 5-9 and Comparative Examples 2-4 In a reactor similar to that of Example 1, 2,6-dimethylnaphthalene (15 g), glacial acetic acid (150 g), cobalt acetate tetrahydrate, manganese acetate tetrahydrate and odor. In the same manner as in Example 1 except that ammonium chloride was used so that the concentrations of cobalt, manganese and bromine elements in the solvent were as shown in Table 2, 2,6
-Produced naphthalene dicarboxylic acid. Obtained 2,6
-The yield of naphthalenedicarboxylic acid is shown in Table 2.

[0021]

[Table 2]

Examples 10-13 2-methylnaphthalene, 1,2-dimethylnaphthalene,
With respect to 2,7-dimethylnaphthalene and 1,2,5,6-tetramethylnaphthalene, 150 g of glacial acetic acid, cobalt acetate tetrahydrate, manganese acetate tetrahydrate and bromide were respectively placed in the same reactor as in Example 1. A naphthalenecarboxylic acid was produced in the same manner as in Example 1 except that ammonium was used so that the concentration in the solvent was as shown in Table 3. The yield of the obtained naphthalenecarboxylic acid is shown in Table 3.

[0023]

[Table 3]

[0024]

According to the present invention, the catalyst cobalt,
By devising the concentrations of manganese and bromine, it is possible to produce naphthalenecarboxylic acid in a high yield using a smaller amount of solvent than in the past, and it is possible to enhance the productivity per solvent unit. Further, the device can be downsized, which is economically advantageous.

Claims (1)

[Claims] 1. A method for producing a naphthalenecarboxylic acid by oxidizing methylnaphthalene in the presence of a lower aliphatic carboxylic acid and a catalyst, wherein (1) 1 part by weight of methylnaphthalene and 5 parts by weight of the lower aliphatic carboxylic acid. Parts by weight and less than 38 parts by weight, and (2) a catalyst containing cobalt, manganese, and bromine as a catalyst is used for the lower aliphatic carboxylic acid and has the following formulas A to C: A: 0.05 ≦ Co + Mn ≦ 1.0 B: 0.5 ≦ Mn / Co ≦ 100 C: Br ≧ 0.001 / Mn (wherein Co, Mn, and Br represent the weight percentages of cobalt, manganese, and bromine atoms with respect to the lower aliphatic carboxylic acid, respectively). A method for producing a naphthalenecarboxylic acid, which comprises using an amount thereof.