JPS62106045A - Improved production of dialkali metal naphthalene-2,6-dicarboxylate - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield by enhanced catalysis, by heating an alkali metal naphthoate in the presence of a catalyst consisting of a zinc compound and a metal halide under pressure of gaseous carbon dioxide. CONSTITUTION:An alkali metal naphthoate or dialkali metal naph thalenedicarboxylate or both are heated in the presence of a catalyst consisting of a zinc compound and a metal halide except zinc halides at 350-500 deg.C, prefer ably 380-470 deg.C under pressure of gaseous carbon dioxide (10-150kg/cm<2>G, particularly 20-100kg/cm<2>G) to afford the aimed compound. An alkali metal halide is preferred for the metal halide and used in a molar amount of 0.1-10 times, particularly 0.2-5 times range based on the zinc compound.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing a dialkali metal salt of naphthalene-2,6-dicarboxylic acid.

Naphthalene-2,6-dicarboxylic acid dialkali metal salt can be easily converted into the corresponding carboxylic acid, that is, naphthalene-2,6-dicarboxylic acid, by acid precipitation, but this naphthalene-2,6-dicarboxylic acid is a raw material for heat-resistant polyester. In recent years, it has attracted attention as an acid moiety, and is a valuable compound in industry (see Japanese Patent Publication No. 54-945).

BACKGROUND OF THE INVENTION Conventionally, the so-called Henkel process has been proposed as one of the methods for producing dialkali metal salts of naphthalene-2,6-dicarboxylic acid. That is, an alkali metal salt of naphthalene monocarboxylic acid (namely naphthoic acid), a dialkali metal salt of naphthalene dicarboxylic acid, or a mixture thereof is heated together with a catalyst to a temperature of 350°C or higher, usually 400 to 500°C, under pressure of carbon dioxide gas. It's a method. Naphthalene-2,6-dicarboxylic acid dialkali metal salt and naphthalene are generated from naphthoic acid alkali metal salt through a disproportionation reaction, and naphthalene-2,6-dicarboxylic acid is generated from naphthalene-2,6-dicarboxylic acid dialkali metal salt through a rearrangement reaction. Dialkali metal salts are selectively produced (a) B, Raec
ke,Angev,Chem,,U,1(195B
) ;b) B, Raecke et al., Org, Syn, C
:all,, Vol, 5, 813 (1973);
C) Yamashita et al., Yuka, 501 (19Ei2); d
) E, McNelis, J, Org, Chets,
, Qian, 1209 (1985); e) U.S. Patent No. 282
No. 3231; f) Japanese Patent Publication No. 51-10224].

Conventionally, cadmium or zinc compounds have been used as catalysts for producing dialkali metal salts of naphthalene-2,6-dicarboxylic acid using the Henkel method. Among these, cadmium compounds such as cadmium chloride are highly toxic and expensive, and have the disadvantage of requiring a large amount of money to recover, but they have excellent catalytic activity. On the other hand, examples of the use of zinc chloride, zinc dioxide, zinc oxide, and zinc carbonate have been reported as zinc compounds;
Although it has low oxidation properties and is inexpensive, its catalytic action is considerably inferior to that of cadmium compounds. Therefore, in order to improve the reaction yield, it has been necessary to use highly toxic and expensive cadmium compounds.

Problems to be Solved by the Invention The inventors of the present invention have conducted extensive studies to solve these problems with conventional catalysts, and have developed a catalyst system that is low in toxicity, economical, and has excellent catalytic action. They discovered this and completed the present invention.

Means for Solving the Problems The present invention uses an alkali metal salt of naphthoic acid and/or a dialkali metal salt of naphthalene dicarboxylic acid in the presence of both a zinc compound and a metal halide (excluding zinc halides) as a catalyst. , a method for producing a dialkali metal salt of naphthalene-2,6-dicarboxylic acid, which is characterized by heating under pressure of carbon dioxide gas.

The raw material for the method of unreleased [51] is an alkali metal naphthoate f
1 or a dialkali metal naphthalene dicarboxylic acid salt, or a mixture thereof. The naphthoic acid alkali metal salt is a 1- or 2-isomer.

Alternatively, mixtures of these can be used. In addition, as a dialkali metal naphthalene dicarboxylic acid salt, 1.2-21
．． 3~, ■, 4-11.5-11.6-11.7-1l
, 8-12.3-52.6-12.7-isomers, or mixtures thereof can be used. However, among the above isomers, the ugly dialkali metal salt of naphthalene-2,6-dicarboxylic acid is the target compound of the present invention, but a mixture containing a small amount of it or a crude mixture with a low purity can be used as the raw material of the present invention. be able to. As for the alkali metal salt, "potassium salt" gives good results as in the usual Henkel method.

In the present invention, both a zinc compound and the metal halide are used as catalysts. In this case, the catalytic action is improved and the yield of the dialkali metal salt of naphthalene-2,6-dicarboxylic acid is also improved as compared to the conventional method in which the zinc compound is used alone.

The lead compounds used in the present invention include zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc halogenide, zinc carboxylates such as zinc naphthoate, zinc naphthalene dicarboxylate, zinc oxide, Examples include various zinc compounds such as zinc carbonate and zinc sulfate, or mixtures thereof. Among these, zinc iodide itself has relatively excellent catalytic action, and when a metal halide of No. 1111 is used in combination as a catalyst, the improvement in catalytic action is not so remarkable. In addition, zinc naphthoate means 1- or 2-isomer or a mixture thereof, and zinc naphthalene dicarboxylate means 1,2-1l, 3-11.4-11.5-1
1.6-11.7-11.8-12.3-12,6-1
2.7-isomer or a mixture thereof.

The amount of these zinc compounds used is usually 0.0% based on the raw material.
It is in the range of 5 to 20mo1%, preferably 1 to lomo1%. The use of a large amount of 20mo more than 1% promotes monomorphism of carbides.

As the metal halides described in 1.J, metal chlorides, metal bromides, and metal iodides are effective in improving the catalytic action, and metal bromides and metal iodides are especially preferred because they are particularly effective. These metal halides can be used in the form of solids or mixtures thereof. Further, as the metal in the metal halide, alkali metal,
Various metals such as alkaline earth metals (excluding zinc).

) is valid. However, it is preferable to use alkali metal halides because of their low toxicity and ease of recovery from the reaction mixture after completion of the reaction, as will be described later. Furthermore, for reasons to be described later, when an alkali metal halide of the same element as the raw material alkali metal salt is used, for example, when the raw material is a sodium salt or a potassium salt, it is particularly desirable to use sodium halide for the former and potassium halide for the latter.

From the above viewpoint, specific examples of preferable metal halides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, rubidium chloride, lithium bromide,
Examples include sodium bromide, potassium bromide, cesium bromide, rubidium bromide, lithium iodide, sodium iodide, potassium iodide, cesium iodide, and rubidium iodide. When the metal halide is an alkali metal halide, the amount used is 0.1 to 10 times the molar amount of the zinc compound, preferably 0.2 to 5 times the molar amount of the zinc compound.
It is twice the molar amount, and a considerable effect is exhibited at 0.2 to 1 times the molar amount. In addition, in the case of metal halides other than alkali metal halides (however, excluding zinc halides), the amount is 0.1 to 5 times the molar amount, preferably 0.2 to 2 times the molar amount of the zinc compound. Therefore, use of more than 2 times the molar amount may result in a decrease in reaction yield.

It is preferable that the raw material, the catalyst zinc compound, and the metal halide are well mixed. For this purpose, there are methods such as adding a catalyst to an aqueous solution of the raw material and mixing well, and then heating and distilling off the water to obtain a mixture of the raw material and catalyst, or thoroughly pulverizing and mixing the raw material and catalyst with a ball mill, etc. However, either method may be used to implement the present invention.

The raw material and catalyst are heated and reacted under pressure of carbon dioxide gas,
In this case, it is also possible to use a substance that is in a liquid state under the reaction conditions and has good stability under the same conditions as a dispersion medium or solvent. Examples of such substances include aprotic polycyclic aromatic compounds having 2 to 3 rings. Specific examples include naphthalene, lower alkylnaphthalenes such as methylnaphthalene and dimethylnaphthalene, diphenyl, lower alkyldiphenyls such as methyldiphenyl and dimethyldiphenyl, diaryl ethers such as diphenyl ether, terphenyl, anthracene, phenanthrene, or mixtures thereof. I hope you can list it. The amount used is 0.5 to 10 times, and usually 1 to 5 times, the amount of raw material.

The pressure of carbon dioxide gas is 10-150Kg/at the reaction temperature.
cm' fist G, preferably 20-100Kg/cm'G
is within the range of In addition, when using the above-mentioned dispersion medium or solvent, 5-
loOKg/am'・G, preferably 10-70
The range is Kg/cm”・G.

The reaction temperature is determined by the raw materials and the zinc compound as a catalyst and i
Although it varies slightly depending on the type of metal halide, it is usually in the range of 350 to 5 (10 °C), from the viewpoint of causing the reaction to occur quickly and suppressing side reactions such as carbide formation.
A range of 380 to 470°C is preferred. The reaction time varies depending on the reaction temperature, but is usually in the range of 5 minutes to 3 hours.

After the reaction is completed, water is added to the reaction mixture to dissolve the dialkali metal salt of naphthalene-2,6-dicarboxylic acid in the water. When a dispersion medium or solvent as described above is used in the reaction, it is dissolved by further adding an organic solvent such as toluene or xylene, and separated from the aqueous layer containing the target product by liquid separation. The zinc compound of the catalyst can be easily separated as zinc oxide or zinc carbonate, which is insoluble in water and the organic solvent, by oxidation or the like, together with the by-product carbide, which is also insoluble.

It is technically easy to recover and regenerate the zinc compound from the insoluble mixture thus obtained and reuse it as a catalyst. Furthermore, since zinc compounds are inexpensive and have low HI properties, it is economically possible to apply appropriate treatment to the insoluble mixture and then use it for other inexpensive uses.

On the other hand, if the metal halide used together as a catalyst is a metal halide other than an alkali metal halide (excluding zinc halide), it will be difficult to dissolve in water due to reaction with carbon dioxide gas or decomposition reaction. zinc, which is also insoluble in water; Separation operations from compounds become complicated, and recovery and regeneration tends to be costly.

On the other hand, when an alkali metal is used as the metal halide, it is dissolved in water together with the naphthalene-2,6-dicarboxylic acid dialka 1) metal salt. Recovery of the alkali metal halide from this aqueous solution and reuse as a catalyst can be carried out very easily by the method described below.

Method (1): Adding a strong acid such as sulfuric acid or hydrochloric acid to the aqueous solution to precipitate naphthalene-2,6-dicarboxylate,
Filter this. The filtrate contains alkali metal halides and alkali metal salts of strong acids, since the latter do not inhibit the reaction of the invention.

The alkali metal halide containing the alkali metal halide is recovered from the filtrate by operations such as concentration and reused as the catalyst of the present invention.

Method (2): Naphthalene is added to the aqueous solution by passing carbon dioxide gas through it.
The monoalkali metal salt of 2,6-dicarboxylic acid is precipitated as a precipitate, which is collected by filtration. The mineral solution contains an alkali metal halide and an alkali metal hydrogen carbonate. Alkali metal hydrogen carbonate easily reacts with naphthoic acid and/or naphthalene dicarboxylic acid and/or an acid anhydride consisting of these. The filtrate is used for this purpose as metal salts are produced. The resulting raw material is mixed with an alkali metal halide, providing one of the most preferred catalyst recovery and reuse methods.

Method (3): When the aqueous solution is concentrated, naphthalene-
The dialkali metal salt of 2,6-dicarboxylic acid is preferentially deposited as a precipitate, which is collected by filtration.

Since the alkali metal halide is dissolved in the filtrate, the alkali metal halide is recovered by a method such as distilling off water and reused as a catalyst.

By the above method or a modification thereof, an alkali metal halide can be easily and economically reused as a catalyst for undeveloped E town. In addition, since an alkali metal halide and a dialkali metal salt of naphthalene-12,6-dicarboxylic acid can cause a metal exchange reaction, in the case of methods (2) and (3), the alkali metals in both are the same. It is preferable from the viewpoint of reproducibility of the recovery operation.

As described above, the dialkali metal salt of naphthalene-2,6-dicarboxylic acid is separated from the reactor as an aqueous solution and converted to naphthalene-2,6-dicarboxylic acid by acid precipitation or the like.

When using both a zinc compound and the metal halide as a working catalyst, compared to using a zinc compound alone,
It was also found that the catalytic action was improved, and there were cases where the catalytic action was equivalent to or higher than that of cadmium compounds (see Examples and Reference side below). The lead compound has low TII property and is inexpensive, and the metal halides, especially alkali metal halides, have low TJ property and can be recovered and reused at low cost.

In the following examples, examples, comparative examples, and reference examples, no occurrence 1! IJ will be further explained in 3T detail.

Examples 1 to 17 To 10.0 g of dipotassium naphthalene-1,8-dicarboxylate 11, that is, dipotassium 1,8-naphthalate, a lead compound and a metal halokenide were added as catalysts in predetermined amounts, respectively, with respect to the dipotassium salt. After adding 1% mole of the mixture and pulverizing it in a whole mill, it was charged into a 200-liter crepe equipped with a stirrer.

The autoclave was heated to 100° C. with or without the addition of 30 g of naphthalene as a dispersion medium or solvent, and after replacing the inside of the autoclave with carbon dioxide gas, carbon dioxide gas was introduced to a predetermined pressure (initial pressure in Table 1).

Then, the mixture in the autoclave was heated to 4℃/
The temperature was raised to a predetermined reaction temperature at a rate of 15 min, and the reaction was further stirred at the same temperature for 1 hour to complete the reaction. After the reaction is complete,
200 d of toluene and 200 d of water were added to the reaction mixture and stirred well. After removing solids that were insoluble in both the aqueous layer and the toluene layer, the aqueous layer was separated. A portion of this aqueous layer was collected, and using high performance liquid chromatography, 1:1 of dipotassium naphthalene 2,6-dicarponate contained therein was determined using an internal standard method, and the yield was calculated. The results are shown in Table 1.

Comparative Examples 1-8 Examples 1-3.9.10.11.12 and 14.15.1
At 6°17, the reaction was carried out in the same manner except that no metal halide was added. The results are shown in Table 1.

Reference Example 1 In Example 1, the reaction was carried out in the same manner as in Example 1 except that cadmium iodide was used in an amount of 8 mo1% based on the raw materials instead of zinc chloride and potassium iodide. The results are shown in Table 1.

(The following is a blank space) Examples 18 to 22 Isomer mixture of naphthalene-2,3-dicarboxylic acid dipotassium salt and naphthalene dicarboxylic acid dipotassium salt, namely 2.6-12.7-1■, 6-11.7-11,3 −
A mixture of isomers, ? -Naphthoic acid potassium salt, ■, 8-
Using either 10 g of a mixture (weight ratio 1:1) of naphthoic acid potassium salt and 2-naphthoic acid potassium salt as raw materials, 8 mo1% of each of the zinc compound and metal halide were added to the raw materials, and 730 g of naphthalene was obtained. 4 in substantially the same manner as in Example 1 in the presence or absence of
The reaction was carried out face-to-face at 50°C, and the product was separated and characterized.

In addition, the charcoal gas resistance pressure is 40kg/Cl1 at 100℃
It is 2.G. The results are shown in Table 2.

Comparative Examples 9-13 In Examples 18-22, the same reactions were carried out without adding the metal halide. The results are shown in Table 2.

Effects of the Invention In the present invention, by using both an inexpensive and low-toxic zinc compound and a metal halide as catalysts, the catalytic action is improved, and dialkali metal naphthalene-2,6-dicarboxylic acid salt can be obtained in good yield. became. As a result, naphthalene-2,6-dicarboxylic acid can now be produced safely and inexpensively, paving the way for industrial production.

Claims (4)

[Claims] (1) Heating an alkali metal naphthoic acid salt and/or a dialkali metal naphthalene dicarboxylic acid salt under pressure of carbon dioxide gas in the presence of both a zinc compound and a metal halide (excluding zinc halides) as catalysts. A method for producing a dialkali metal salt of naphthalene-2,6-dicarboxylic acid, characterized by: (2) The metal halide is a metal chloride, a metal bromide,
Alternatively, the manufacturing method according to claim (1), which is a metal iodide. (3) The manufacturing method according to claim (1), wherein the metal halide is an alkali metal halide. (4) The manufacturing method according to claim (1), wherein the metal halide is an alkali metal chloride, an alkali metal bromide, or an alkali metal iodide.