JP2903233B2 - Method for producing high-purity dimethyl diphenyldicarboxylate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The dimethyl 4,4'-diphenyldicarboxylate obtained in the present invention is a copolymer of polyester described in JP-B-56-33382 or JP-A-63-63638. One of the components is used for fibers, films, resins and the like.

(Prior art) Polyester containing 4,4'-diphenyldicarboxylic acid or its ester as a copolymer component is applied to fiber, film, plasticizer, resin, etc. as a material excellent in heat resistance and rigidity. However, high-purity 4,4'-diphenyldicarboxylic acid or an ester thereof is particularly required in order to exhibit excellent functions.

However, as a method for producing 4,4′-diphenyldicarboxylic acid, a method is known in which 4-chlorobenzoic acid is coupled in an aqueous alkali hydroxide solution in the presence of a palladium-supported catalyst (US Pat. No. 2,809,210). However, the obtained 4,4'-diphenyldicarboxylic acid has a high boiling point and a very low solubility in a solvent, so that it is very difficult to purify it and it is difficult to obtain a highly purified one. (Refer to Comparative Examples 1, 2, and 3.) On the other hand, dimethyl 4,4'-diphenyldicarboxylate is easily used for the same purpose because it is easily distilled and recrystallized and purified, and is extremely excellent.

Therefore, various methods have been proposed. For example, 4,4 '
A method for producing dimethyl 4,4'-diphenyldicarboxylate by esterifying -diphenyldicarboxylic acid in the presence of an acid catalyst has been proposed (Japanese Patent Publication No. 56-33382). The above method does not proceed under normal esterification conditions and requires a special reactor because it must be carried out under pressure in an autoclave. Also, a method of oxidizing 4,4'-diethyldiphenyl with molecular oxygen (JP-A-63-63638)
Requires an autoclave and requires a long process to industrially obtain 4,4'-diethyldiphenyl of high purity. Further, a method of reacting 4,4′-dibromodiphenyl with carbon monoxide in the presence of dimethyl carbonate (US Pat. No. 363283)
No. 1) has been proposed. However, handling bromine compounds has problems such as corrosion of the apparatus. Thus, there was no satisfactory method for industrial production of dimethyl 4,4'-diphenyldicarboxylate with high purity.

(Problems to be Solved by the Invention) The present invention solves the conventional problems and provides a method for producing high-purity dimethyl 4,4'-diphenyldicarboxylate by an industrial method.

(Means for Solving the Problems) As a result of intensive studies on a method for industrially producing high-purity dimethyl 4,4'-diphenyldicarboxylate, the present inventor has found that high-purity, easily available industrial raw materials are obtained. By reacting methyl 4-chlorobenzoate or 4-chlorobenzoic acid chloride in dry methanol in the presence of an alkali metal or alkaline earth metal carbonate, and a supported palladium catalyst, it is easy to obtain a highly pure 4,4 The inventors have found that dimethyl 4'-diphenyldicarboxylate is obtained, and completed the present invention.

That is, the present invention relates to the general formula (Wherein, R represents a methoxy group or a halogen atom,
X represents a halogen atom. A) a general formula from the halogenobenzene carboxylic acid derivative represented by In the method for producing dimethyl diphenyldicarboxylate represented by the formula, dimethyl diphenyldicarboxylate characterized by reacting in a methanol solvent in the presence of an alkali metal or alkaline earth metal carbonate and a supported palladium catalyst How to

The halogenobenzenecarboxylic acid derivative represented by the general formula (I) used in the present invention includes, for example, 4-
Methyl chlorobenzoate, methyl 3-chlorobenzoate, 4
-Chlorobenzoic acid chloride. Examples of the alkali metal or alkaline earth metal carbonate used in the reaction include sodium carbonate, potassium carbonate, calcium carbonate and the like, and among them, potassium carbonate is more preferable. The amount of the alkali metal or alkaline earth metal carbonate to be used is not particularly limited, but may be 1 to 20 with respect to the halogenobenzene carboxylic acid derivative.
Equivalents are preferred, and particularly preferably 2 to 6 equivalents.
The palladium catalyst used in the present invention may be a simple substance, but palladium is activated carbon, silica, alumina, zeolite,
Those supported on a carrier such as magnesia, graphite, calcium carbonate and the like are preferable, and a catalyst supported on activated carbon is particularly preferable. In these supported palladium catalysts, it is preferable that palladium is usually supported on the carrier in an amount of about 0.1 to 20% by weight, particularly about 0.5 to 10% by weight. The amount of the catalyst used is 0.01 to 100 mmol, preferably 0.01 to 5 mmol in terms of metal atom, per 1 mol of the halogenobenzenecarboxylic acid derivative.
0 mmol. Further, the solvent used is methanol, and the use of dry methanol is particularly preferred. In particular, the inclusion of water is not preferred because it involves hydrolysis.

The reaction may be carried out under pressure, but the reaction is usually carried out under normal pressure. The reaction temperature is 0 to 300
In particular, the temperature is preferably from 50 ° C to the boiling point of the solvent.

(Effect of the Invention) The method of the present invention comprises a step of supporting a halogenobenzene derivative represented by the general formula (I), which is high-purity and easily available as an industrial material, with an alkali metal or alkaline earth metal carbonate in dry methanol. By reacting in the presence of a palladium catalyst, the formation of by-products such as hydrolysis is suppressed, and highly pure dimethyl 4,4′-diphenyldicarboxylate represented by the general formula (II) is easily obtained. The purification process is highly valuable as an industrial production method because the purification process can be simplified. In particular, it is surprising that according to the method of the present invention, dimethyl 4,4'-diphenylcarboxylate can be obtained with a high purity of 99.9% or more without any particular purification.

(Examples) Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 (Synthesis of dimethyl 4,4'-diphenyldicarboxylate) In a 200 ml four-necked flask, 13.82 g of anhydrous potassium carbonate and 60 ml of dry methanol were charged and stirred under a nitrogen atmosphere. Under a nitrogen atmosphere, 1 g of a 5% palladium-carbon catalyst (manufactured by Nippon Engelhard Company) previously mixed with 30 ml of dry methanol was charged and the temperature was raised to the boiling point of methanol. 8.53 g of methyl 4-chlorobenzoate dissolved in 10 ml of dry methanol was charged and reacted at the same temperature for 2 hours.
After cooling to room temperature, the contents were separated by filtration to obtain a residue. The organic matter was extracted from the residue with chloroform, and the chloroform solution was concentrated after filtration, and the precipitate was filtered, washed and dried to obtain 3.03 g of dimethyl 4,4′-diphenyldicarboxylate having a melting point of 217 to 219 ° C. . The yield was 4.48% and the purity was 99.9%.

Example 2 (Synthesis of dimethyl 4,4'-diphenyldicarboxylate) Instead of methyl 4-chlorobenzoate of Example 1, 4-
8.75 g of chlorobenzoic acid chloride and 20.73 of potassium carbonate
g was used and the others were the same. As a result, 2.81 g of dimethyl 4,4′-diphenyldicarboxylate was obtained. Yield 41.6
%, The purity was 99.9%.

Example 3 (Synthesis of dimethyl 4,4′-diphenyldicarboxylate) Instead of potassium carbonate of Example 2, sodium carbonate 1
Using 5.90 g, the other conditions were the same and reacted for 7 hours. As a result, the conversion was 56%, but 1.63 g of dimethyl 4,4′-diphenyldicarboxylate was obtained. Yield 24.1%, purity 9
9.9%.

Example 4 (Synthesis of diethyl 4,4'-diphenyldicarboxylate) The procedure of Example 2 was repeated, except that dry ethanol was used instead of dry methanol of Example 2. As a result, when the product was confirmed, it was confirmed that 12.4% of diethyl 4,4′-diphenyldicarboxylate was produced (confirmed by gas chromatography total area method) at a conversion of 36%.

Comparative Example 1 (Synthesis of dimethyl 4,4′-diphenyldicarboxylate) Instead of the dry methanol in Example 1, a mixed solvent of methanol and water (9: 1) was used, and the other steps were carried out in the same manner. As a result, dimethyl 4,4'-diphenyldicarboxylate is
Only 22.9% (internal standard method) was obtained.

Comparative Example 2 (Synthesis of 4,4′-diphenyldicarboxylic acid) In Example 1, 4-chlorobenzoic acid was used instead of methyl 4-chlorobenzoate, and a mixed solvent of methanol and water (5 Paired 6) was reacted using potassium hydroxide instead of potassium carbonate. As a result,
4.52 g (74.6% yield) of 4'-diphenyldicarboxylic acid was obtained. However, the purity is 86.8% (liquid chromatography)
Thus, high-purity 4,4'-diphenyldicarboxylic acid could not be obtained by recrystallization purification.

Comparative Example 3 (Synthesis of dimethyl 4,4'-diphenyldicarboxylate) The same procedure as in Example 2 was repeated except that potassium hydroxide was used instead of potassium carbonate. However, benzoic acids generated by the hydrolysis reaction were the main products, and dimethyl 4,4'-diphenyldicarboxylate was not obtained at all.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C07C 69/76 C07C 67/14 C07C 67/343 C07C 15/14 C07B 61/00 B01J 23/44 WPI / L (QUESTEL) CA (STN)

Claims (1)

(57) [Claims] (1) General formula (Wherein, R represents a methoxy group or a halogen atom;
Represents a halogen atom. Wherein the halogenobenzenecarboxylic acid derivative represented by the general formula (1) is reacted in a methanol solvent in the presence of an alkali metal or alkaline earth metal carbonate and a supported palladium catalyst. A method for producing dimethyl diphenyldicarboxylate represented by the formula: