JPH013148A - Method for producing 2,6-naphthalene dicarboxylic acid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to oxidizing 2,6-dimethylnaphthalene to produce 2.6-dimethylnaphthalene.
The present invention relates to a method for producing 6-naphthalene dicarboxylic acid.

More specifically, the present invention relates to a method for producing 2,6-naphthalene dicarboxylic acid in high yield by oxidizing 2,6-dimethylnaphthalene in the presence of an aliphatic carboxylic acid and an aromatic compound.

(Prior art) As a method for producing 2.6-naphthalene dicarboxylic acid, a method is known in which potassium salt of 1,8-naphthalene dicarboxylic acid is isomerized in the presence of carbon dioxide using cadmium chloride as a catalyst. ing.

In addition, a method of producing terephthalic acid and the like by oxidizing alkyl-substituted aromatic hydrocarbons with molecular oxygen has been known for a long time, and by applying this method, 2,6-naphthalene dicarboxylic acid is produced from 2,6-dimethylnaphthalene. Methods for producing acids are also known. That is, JP-A-48-34153 and JP-A-49-42654 disclose that 2,6-dimethylnaphthalene is treated with molecular oxygen in an acetic acid solvent in the presence of an oxidation catalyst containing cobalt, manganese and bromine. A method for producing 2,6-naphthalene dicarboxylic acid by oxidation is disclosed. However, in these methods, unless the molar ratio of 2,6-dimethylnaphthalene to acetic acid in the reaction system is kept at a low level of 1/100 or less, oxidized intermediates such as 6-formyl-2-naphthoic acid will be produced. However, there was a drawback in that 2.6-nafclean dicarboxylic acid could not be obtained in high yield. That is, these methods have low productivity per unit amount of solvent and are disadvantageous as industrial production methods.

[Problem that the invention seeks to solve]

Therefore, the present invention provides a method for producing 2,6-naphthalene dicarboxylic acid from 2,6-dimethylnaphthalene in the presence of an oxidation catalyst containing cobalt, manganese, and bromine. An object of the present invention is to provide a method capable of producing 2,6-naphthalene dicarboxylic acid with a yield as high as or higher than conventional methods even under conditions where the concentration of 2,6-naphthalene dicarboxylic acid (molar ratio relative to acetic acid) is higher.

That is, the present invention increases the concentration of 2,6-dimethylnaphthalene in acetic acid and increases the productivity per unit amount of solvent.
- An object of the present invention is to provide a method for producing naphthalene dicarboxylic acid.

[Means for solving problems]

The present invention is a method for producing 2,6-naphthalene dicarboxylic acid by oxidizing 2,6-dimethylnaphthalene with molecular oxygen in the presence of a catalyst containing cobalt, manganese, and bromine, the method comprising: The present invention relates to a method for producing 2,6-naphthalene dicarboxylic acid, which is carried out in the presence of an acid and an aromatic compound.

The present invention will be explained below.

In the present invention, examples of the "catalyst containing cobalt, manganese and bromine" include those disclosed in JP-A No. 48-34153 (Japanese Patent Publication No. 56-3337) and JP-A No. 49-4265'.
The conventionally known oxidation catalyst containing cobalt, manganese and bromine described in Publication No. 4 can be used as is. That is, the above catalyst used in the present invention is
Catalysts containing elemental or compound cobalt, manganese and bromine, especially those soluble in acetic acid, are preferred.

Examples of the cobalt and manganese compounds contained in the catalyst include cobalt and manganese containing 1 carbon atoms, such as formic acid, acetic acid, propionic acid, acetic acid, oxalic acid, maleic acid, etc.
~4 aliphatic carboxylic acid salts: salts of alicyclic carboxylic acids such as naphthenic acid; salts of aromatic carboxylic acids such as benzoic acid, terephthalic acid, naphthoic acid naphthalene dicarboxylic acid; hydroxides, oxides, bromides Examples include inorganic compounds such as: Particularly preferred are aliphatic carboxylates, and cobalt acetate and manganese acetate are most suitable. These cobalt salts and manganese salts may be anhydrous salts or hydrated salts.

Furthermore, examples of the bromine compound contained in the catalyst include hydrogen bromide, hydrobromic acid, metal salts of hydrobromic acid, ammonium bromide, and organic bromine compounds. Preferred bromine compounds include hydrobromic acid, ammonium bromide, sodium bromide, potassium bromide, cobalt bromide, manganese bromide, and bromoacetic acid.

As the molecular oxygen used in the present invention, for example, pure oxygen and a mixed gas of oxygen and an inert gas (eg, nitrogen, helium, argon, etc.) are used. Air can also be used directly as a source of molecular oxygen.

The "aliphatic carboxylic acid" used in the present invention includes:
Examples include acetic acid, propionic acid, butyric acid, and the like. Particularly preferred is acetic acid.

Examples of the "aromatic compound" include compounds represented by the formula (wherein, X is a halogen and n is an integer of 0 to 3). In the formula, X is preferably chlorine or bromine, and preferably n=o, 1.2. Specific examples of the compound represented by formula (I) include benzene, chlorobenzene, dichlorobenzene, bromobenzene, dibromobenzene, and the like.

In the present invention, there are no particular limitations on the amounts of the aliphatic carboxylic acid and aromatic compound used and the ratio of the two. The aliphatic carboxylic acid may be present in an amount necessary to dissolve the cobalt compound, manganese compound, bromine compound, etc. used as a catalyst.

The mixing ratio of the aromatic compound and the aliphatic carboxylic acid is 1 part aliphatic carboxylic acid to 0.5 part aromatic compound by volume.
-10, preferably 1-5 is appropriate.

The amounts of the cobalt compound and manganese compound added as catalysts to the reaction system are 0.001 to 1.0 gram atoms of cobalt and manganese, respectively, per 1β of the mixture of aliphatic carboxylic acid and aromatic compound. It is preferable that the amount is 0.002 to 0.5 gram atom. In addition, the amount of bromine or bromine compound added to the reaction system is such that at least 0 bromine atoms are added to 1 p of the mixture of aliphatic carboxylic acid and aromatic compound.
, o o i to 3.0 gram atoms.

In the method of the present invention, the raw material 2,6-dimethylnaphthalene is 0.05 to 2.0 mol, preferably 0 mol, based on the mixture 11 of aliphatic carboxylic acid and aromatic compound.
．． It can be added to the reaction system in an amount of 1 to 1.0 mol. However, the amount of 2,6-dimethylnaphthalene added also varies depending on the mixing ratio of aliphatic carboxylic acid and aromatic compound.

In the method of the present invention, the reaction temperature is 120-260°C, preferably 140-240°C.

When the reaction temperature is lower than 120°C, the yield of 2,6-naphthalene dicarboxylic acid tends to decrease. Furthermore, if the reaction temperature is higher than 260° C., trimellitic acid and the like are likely to be produced by oxidative cleavage of naphthalene nuclei, and aliphatic carboxylic acids such as acetic acid used as a solvent are likely to be burned.

The pressure within the reaction system is not particularly limited as long as it is equal to or higher than the vapor pressure of the reaction mixture. However, the oxygen partial pressure is usually 0.5 kg.
/cff1 or more, preferably at least 1.0 kg10+f. The reaction is carried out by bubbling oxygen-containing gas (eg air) into the reaction mixture to maintain a predetermined pressure and can be carried out batchwise or continuously.

The reaction time is 0.15 to 5 hours, preferably 0.25 hours.
~2 hours is appropriate.

(Example) The present invention will be further explained below with reference to Examples.

Example 1 In a titanium reactor with a capacity of 100 ml, 30 ml of glacial acetic acid and 3 Qmf of orthodichlorobenzene were added as solvents. ,
Add 4.68g of 2.6-dimethylnaphthalene
, 0.300 g of cobalt acetate tetrahydrate, 4 manganese acetate
After charging 0.293 g of aqueous salt and 0.493 g of sodium bromide, the mixture was heated at a temperature of 160°C and a pressure of 3.5 kg/cffiG while blowing oxygen into the liquid phase at a rate of 0.5 L/min.
The reaction was carried out for 0 minutes. The solvent of the reaction mixture was distilled off, washed with hot acetic acid, and then passed through the mouth.

As a result of analyzing the obtained solid and the products in the oral fluid, 2.
The yield of 6-naphthalene dicarboxylic acid was 86.4 moβ% as shown in Table 1.

Comparative Example 1 Glacial acetic acid was used as a solvent at 60 mA, and the reaction time was 90 mA.
The test was carried out in the same manner as in Example 1 except that the test time was for 1 minute. 2,
The yield of 6-naphthalene dicarboxylic acid is 77.6moβ%
6-acetoxymethyl-2-naphthoic acid is 9.
5 moA% was produced.

Examples 2 to 4 Instead of orthodichlorobenzene, bromobenzene was used in Example 2, chlorobenzene was used in Example 3, and benzene was used in Example 4 instead of orthodichlorobenzene. In Example 4, the pressure was 7.5 kg/ The reaction was carried out in the same manner as in Example 1 except that c++fG was used and the reaction time was 30 minutes.

Example 5 The same procedure as in Example 1 was carried out except that the reaction temperature was 180° C., the pressure was 5.4 kg/cIIIG, and the reaction time was 30 minutes. As a result, the yield of 2,6-naphthalene dicarboxylic acid was 93.5 mOβ%.

Comparative Example 2 5Qmj of glacial acetic acid as a solvent! The same procedure as in Example 5 was carried out except for binding. The yield of the produced 2,6-naphthalene dicarboxylic acid was 77.7 moβ%, and the yield of 6-formyl-2-naphthoic acid was 17.5 moβ%.

Comparative Example 3 The same procedure as Comparative Example 2 was carried out except that the reaction time was 90 minutes. The yield of 2.6-naphthalene dicarboxylic acid was 80.9mo42%, but 12.5mob% of 6-acetoxymethyl-2-naphthaldehyde was produced.

Example 6 The same procedure as in Example 5 was carried out except that 12 ml of glacial acetic acid and 48 ml of orthodichlorobenzene were used as the solvents.

Example 7 0.199 g of cobalt acetate tetrahydrate as a catalyst.

The same procedure as in Example 5 was carried out except that the amount of manganese acetate tetrahydrate was 0.049 g and the amount of sodium bromide was 0.103 g.

Example 8 0.051 g of cobalt acetate tetrahydrate as a catalyst.

The same procedure as in Example 5 was carried out except that the amount of manganese acetate tetrahydrate was 0.196 g and the amount of sodium bromide was 0.103 g.

Example 9 0.1.49 g of cobalt acetate tetrahydrate as a catalyst.

The same procedure as in Example 5 was carried out except that the amount of manganese acetate tetrahydrate was 0.147 g and the amount of sodium bromide was 0.246 g.

Example 10 1.25 g of 2.6-dimethylnaphthalene acid, 0.195 g of cobalt acetate tetrahydrate, 0 g of manganese acetate tetrahydrate
．． The same procedure as in Example 5 was carried out except that the amount of ammonium bromide was 192 g and 0.100 g.

The yield of 2.6-naphthalene dicarboxylic acid is 96.9 mo
It was 1%.

(Effect of the invention) According to the method of the invention, 2.6
-2,6-naphthalene dicarboxylic acid can be produced in high yield while maintaining the concentration of -dimethylnaphthalene higher than before, and productivity per unit amount of solvent can be increased.

Claims (2)

[Claims] (1) A method for producing 2,6-naphthalene dicarboxylic acid by oxidizing 2,6-dimethylnaphthalene with molecular oxygen in the presence of a catalyst containing cobalt, manganese, and bromine, the method comprising: and a method for producing 2,6-naphthalene dicarboxylic acid, which is carried out in the presence of an aromatic compound. (2) A patent claim in which the aromatic compound is a compound represented by the formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) (wherein, X is a halogen and n = an integer from 0 to 3) The method described in paragraph (1).