JPH09143122A - Production of diphenyl oxalate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method for producing highly pure diphenyl oxalate by heating the crystalline adduct of diphenyl oxalate to phenol in a specific molar ratio and subsequently subjecting the melted liquid to a treatment for evaporating or distilling off the phenol. SOLUTION: This method for producing the diphenyl oxalate comprises heating and/or maintaining the new crystalline diphenyl oxalate-phenol adduct containing the diphenyl oxalate and the phenol in a molar ratio of 1:2 within a temperature range of preferably 100-300 deg.C especially 190-250 deg.C, and subjecting the melted liquid to the evaporation or distillation of the phenol at the atmospheric pressure, preferably under a vacuum of 2-500mmHg. By the method, the highly pure diphenyl oxalate can massively be produced in an industrial scale. The diphenyl oxalate is useful as a raw material and an additive for producing intermediates used for various medicines, various agrochemicals, etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a highly pure diphenyl oxalate from a crystalline adduct of diphenyl oxalate and phenol having a molar ratio of diphenyl oxalate to phenol (diphenyl oxalate: phenol) of 1: 2. It relates to a method of manufacturing. The diphenyl oxalate obtained by the present invention is a compound useful as a raw material for the production of intermediates for various pharmaceuticals and agricultural chemicals, or a raw material for the production of polymers and additives.

Crystalline adducts of diphenyl oxalate and phenol are crystalline adducts of diphenyl oxalate and phenol from the melt mixture which are maintained at temperatures below 100 ° C. in which the molten mixture of diphenyl oxalate and phenol is homogeneously melted. It is a novel substance obtained by precipitating and separating / recovering a sex addition product.

[0003]

2. Description of the Related Art At present, diphenyl oxalate is not produced on a large scale on an industrial scale, and there is no known method for producing diphenyl oxalate capable of producing high-purity diphenyl by an industrially suitable method. It was

On the other hand, in the laboratory, crude diphenyl oxalate (diphenyl oxalate, transesterification reaction solution containing phenol, etc.) is distilled to distill oxalate diphenylate to obtain high-purity diphenyl oxalate. Although the method of obtaining it was carried out, if such a method by distillation is to be carried out on an industrial scale, diphenyl oxalate is a high-boiling compound (boiling point: 320 ° C.), so that distillation is carried out at a high temperature. However, there is a problem that it causes deterioration of diphenyl oxalate and other useful components (unreacted raw materials, etc.) during distillation.

Further, the separation / recovery of such a high boiling point compound by distillation itself requires operation under a high depressurized state, which not only complicates the apparatus but also requires considerable energy, which is industrially satisfactory. It wasn't possible.

Japanese Unexamined Patent Publication (Kokai) No. 6-172270 discloses a crystalline adduct of diphenyl carbonate and phenol, and a method of heating the crystalline adduct to remove phenol to obtain diphenyl carbonate. However, that diphenyl oxalate can form crystalline adducts with phenol,
Further, it has not been known at all that high-purity diphenyl oxalate can be obtained from the crystalline adduct.

[0007]

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide an industrially suitable method for producing diphenyl oxalate capable of producing a large amount of highly pure diphenyl oxalate on an industrial scale. is there.

[0008]

Means for Solving the Problems The present inventors have been earnestly researching a method for producing diphenyl oxalate, and in the process, they first found a crystalline adduct containing diphenyl oxalate and phenol, Furthermore, the inventors have for the first time found that high-purity diphenyl oxalate can be easily obtained from the crystalline adduct, and have completed the method for producing diphenyl oxalate of the present invention, which is useful as a method for producing diphenyl oxalate. That is, according to the present invention, a crystalline adduct of diphenyl oxalate and phenol having a molar ratio of diphenyl oxalate and phenol (diphenyl oxalate: phenol) of 1: 2 is heated to form a melt, and its liquid phase state is obtained. The method for producing diphenyl oxalate is characterized in that phenol is removed from the molten liquid by evaporation or distillation.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The adduct of diphenyl oxalate and phenol can be confirmed to have a molar ratio of diphenyl oxalate to phenol (diphenyl oxalate: phenol) of 1: 2 by gas chromatography or the like. It is a new substance that can be produced, and has a formula weight: 430.4.
6. Melting point: 101 to 103 ° C.

The crystalline adduct of diphenyl oxalate and phenol of the present invention has, for example, an FT-IR spectrum as shown in FIG. 1 and is shown in Table 1 by nuclear magnetic resonance (H ¹ -NMR) analysis. It is a substance having the peak shown in.

[0011]

[Table 1]

The above-mentioned crystalline adduct of diphenyl oxalate and phenol is a molten mixture in which diphenyl oxalate and phenol are uniformly melted at a temperature lower than 100 ° C.,
Preferably 40 to 95 ° C, more preferably 45 to 85 ° C
Maintained at and a crystalline adduct of diphenyl oxalate and phenol having a molar ratio of diphenyl oxalate to phenol (diphenyl oxalate: phenol) of 1: 2 is precipitated from the melt mixture.

As an embodiment of the method for obtaining the above-mentioned crystalline adduct, for example, a molten mixture in which diphenyl oxalate and phenol are uniformly melted is heated to a temperature of 100 ° C. or higher, and then heated. The homogeneous liquid phase melt mixture was cooled to a crystallization temperature in the range of about 10 to 95 ° C. as described above, and the molar ratio of diphenyl oxalate to phenol (diphenyl oxalate: phenol) was 1: 2. A certain crystalline adduct of diphenyl oxalate and phenol is precipitated from the molten mixture, and the precipitated crystalline adduct is separated and recovered from the molten mixture in the liquid phase state by an ordinary crystal separation means such as filtration or centrifugation. The method can be preferably mentioned.

In the above-mentioned molten mixture, the ratio of diphenyl oxalate to the total amount of diphenyl oxalate and phenol is 1 to 50% by weight, particularly 2 to 45% by weight, and the diphenyl oxalate and phenol are homogeneous. It is preferable that the molten mixture is in a liquid phase state in which it is melted.
The melt mixture contains diphenyl oxalate and phenol in a total concentration of diphenyl oxalate and phenol of 50% by weight or more, especially 60 to 1 with respect to the melt mixture.
It is preferably contained in an amount of 00% by weight, more preferably 65 to 95% by weight. Further, the above-mentioned molten mixture has a temperature of 100 ° C. or higher, particularly 120 to 300 ° C., and further 140 to 250 ° C.
It is preferably used as a liquid-state molten mixture obtained by heating in the temperature range of.

As the above-mentioned molten mixture, a reaction solution obtained by various methods for producing diphenyl oxalate, in which diphenyl oxalate and phenol are dissolved, for example, ester of oxalic acid dichloride and phenol in the presence of an alkali catalyst. Or a reaction liquid obtained by the reaction, a dialkyl oxalate and phenol or carboxylic acid phenyl ester,
The reaction liquid obtained by transesterification with a phenol derivative such as diphenyl carbonate in the presence of a suitable catalyst can be used as it is. In addition, a composition prepared by adding phenol or the like to these reaction solutions as described above, or 80 to 100% by weight of diphenyl oxalate and 80 to 100% by weight.
It is also possible to use a mixture obtained by mixing 100% by weight of phenol with an appropriate ratio and heating and melting this mixture. In order to industrially obtain the above-mentioned crystalline adduct, it is particularly preferable to use a reaction liquid in a liquid phase state of 100 ° C. or higher obtained by transesterification of dialkyl oxalate and phenol as it is as a melt mixture. .

In the present invention, the operation of heating the crystalline adduct of diphenyl oxalate and phenol to obtain a melt thereof is carried out by melting the above crystalline adduct at a melting point (101 to 103 ° C.).
Above, it is preferable to carry out by heating to 138 ° C. or higher. The temperature at this time is preferably maintained at 300 ° C. or lower, particularly 250 ° C. or lower, and further 220 ° C. or lower in order to prevent thermal degradation of diphenyl oxalate and the like.

The operation of removing the phenol from the melt by evaporation or distillation is carried out at a temperature of the melt of 30.
It is preferable to carry out under atmospheric pressure or reduced pressure while maintaining at 0 ° C or lower, particularly 250 ° C or lower, and further 220 ° C or lower. In addition, the removal operation of phenol by this evaporation or distillation,
There is no problem even if it is carried out at the same time as the operation of obtaining the melt by the above heating.

In order to obtain high-purity diphenyl oxalate in the above operation, it is preferable that the melt used in the above-mentioned operation for removing phenol by evaporation or distillation is always kept in a liquid phase state. That is, since the melting point of diphenyl oxalate is 138 ° C., the molten liquid (can liquid) is a molten liquid in which the concentration of diphenyl oxalate is gradually increased by evaporation or distillation, or oxalic acid as the final target. It is preferable that the temperature be maintained at 138 ° C. or higher, particularly 140 ° C. or higher, and even 145 ° C. or higher, including the melt (can solution) in which almost all diphenyl is formed, and always in the liquid phase.

Therefore, in the present invention, the melt in the liquid phase state is heated and / or maintained within the range of 100 to 300 ° C., particularly 140 to 250 ° C., and further 145 to 220 ° C. Phenol is preferably removed from the bottom liquid by evaporation or distillation to obtain high-purity (substantially 100% pure) diphenyl oxalate. The temperature of the melt may be gradually raised to the above temperature range as the concentration of diphenyl oxalate in the melt increases during the evaporation or distillation operation.
The temperature may be increased stepwise multiple times, such as a temperature range of ˜140 ° C. and then a temperature range of 140˜250 ° C.

The operation of removing the phenol from the melt by evaporation or distillation may be carried out under normal pressure. In that case, the melt is at the boiling point of phenol, 182 ° C.
It is necessary to heat and / or maintain the above temperature, preferably 190 ° C. or more. That is, this evaporation or distillation operation is carried out under normal pressure at 182 to 300 ° C., particularly 190 to 250.
It is preferable that the heating is carried out in the temperature range of 90 ° C, more preferably 190 to 220 ° C. Further, in the present invention, in order to reduce the thermal deterioration of diphenyl oxalate and the like, the operation of removing the phenol from the melt by evaporation or distillation is performed in the range of 100 to 300 ° C. for the melt in the liquid phase state. Heating and / or maintaining inside, suitable depressurized state, ie 2-500 mm
It is more preferable to carry out under reduced pressure of Hg, especially about 5 to 200 mmHg.

The diphenyl oxalate thus obtained has a high purity of 95% by weight or more, particularly 97 to 100% by weight, and can be used in various applications as described above.

[0022]

EXAMPLES Next, the present invention will be specifically described with reference to Reference Examples and Examples for the preparation of a crystalline adduct of diphenyl oxalate and phenol. Reference example 10 with thermometer, stirrer and Vigreux-type fractionator
Dimethyl oxalate (manufactured by Wako Pure Chemical Industries, Ltd.) 118.0 g (1.00 mol) and phenol (manufactured by Wako Pure Chemical Industries, Ltd.) 470.2 g (5.00 mol) in a 00 ml glass round bottom flask.
And tetraphenoxy titanium 1.01 g (0.0024
(mol) was charged, and heating was started in an oil bath provided outside. Then, while stirring, while removing methanol produced by the reaction, the temperature was raised to 180 to 200 ° C. and the transesterification reaction was carried out for 8 hours. After completion of the reaction, the reaction mixture was analyzed by gas chromatography to find that diphenyl oxalate was 21.38% by weight, methylphenyl oxalate was 12.47% by weight, dimethyl oxalate was 3.86% by weight, and phenol was 62% by weight. The content was 0.05% by weight.

The heating of the obtained reaction solution was stopped, and the temperature was gradually lowered from 180 to 200 ° C. while continuing stirring. Crystals began to precipitate from about 85 ° C, but the temperature was lowered to 60 ° C to carry out crystallization. The precipitated crystals were collected by filtration at 60 ° C, and the obtained crystals were washed with about 50 ml of phenol. The filtrate contains 3.05% of diphenyl oxalate.
% By weight, methylphenyl oxalate 18.42% by weight,
Dimethyl oxalate is 5.72 wt%, phenol is 7
The content was 2.80% by weight.

Example 1 150 g of the crystals in the wet state obtained in the reference example were placed in a simple distillation apparatus and subjected to a reduced pressure of 20 mmHg at 110 to 120 ° C.
It was heated to 0 ° C. and the phenol was distilled off. The obtained diphenyl oxalate 74.3 g had a purity of 99% or higher when analyzed by gas chromatography.

The above crystals were dried under reduced pressure at 60 ° C. for 5 hours, and then the oxalic acid having a molar ratio of diphenyl oxalate to phenol (diphenyl oxalate: phenol) of 1: 2 was analyzed by the following analysis. It was confirmed to be a crystalline adduct of diphenyl and phenol.

[Melting Point Measurement] The melting point of the crystal was measured and found to be 101 to 103 ° C. This was different from both diphenyl oxalate and phenol.

[Gas Chromatographic Analysis] When the above crystals were dissolved in acetonitrile and analyzed by gas chromatography, diphenyl oxalate and phenol were detected in addition to acetonitrile, and the weight ratio of phenol to diphenyl oxalate was 1. It was 0.78. When this ratio was expressed by a molar ratio, it corresponded to diphenyl oxalate: phenol (molar ratio) = 1: 2.

[GC-MS Analysis] GC of the above crystals
-MS analysis confirmed diphenyl oxalate with molecular weight 242 and phenol with molecular weight 94.

[Elemental analysis] When the above-mentioned crystals were subjected to elemental analysis, analytical values corresponding to diphenyl oxalate: phenol (molar ratio) = 1: 2 were obtained as follows.

[0030]

[Table 2]

[FT-IR] FIG. 1 shows the FT-IR spectrum of the above crystal.

[0032] [H ¹ -NMR] H ¹ -NMR of the crystal
The results of the analysis are shown below. δ (CDCl ₃ ) ppm 4.85 (2H, s) 6.82 (4H, d) 6.92 (2H, t) 7.23 (8H, m) 7.32 (2H, t) 7.46 ( 4H, t)

[0033]

INDUSTRIAL APPLICABILITY According to the present invention, in the production of diphenyl oxalate, particularly in the production of diphenyl oxalate by a transesterification reaction, highly purified oxalate can be produced by an industrially suitable method without purification of diphenyl oxalate. Diphenyl acid can be produced. Therefore, it is possible to provide a manufacturing process of diphenyl oxalate that is industrially sufficiently satisfactory from the aspect of equipment and energy.

[Brief description of the drawings]

FIG. 1 shows an FT-IR spectrum of the crystal obtained in Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Satoru Fujitsu 10 1978, Kogushi, Ube City, Yamaguchi Prefecture Ube Kosan Co., Ltd.

Claims (4)

[Claims] 1. A crystalline adduct of diphenyl oxalate and phenol, which has a molar ratio of diphenyl oxalate to phenol (diphenyl oxalate: phenol) of 1: 2, is heated to form a melt, which is in the liquid phase state. A process for producing diphenyl oxalate, which comprises removing phenol from a melt by evaporation or distillation. 2. The diphenyl oxalate according to claim 1, wherein the melt in the liquid state is heated and / or maintained within a range of 100 to 300 ° C. to remove phenol by evaporation or distillation. Manufacturing method. 3. The shu according to claim 1, wherein the melt in a liquid phase state is heated and / or maintained within a range of 190 to 250 ° C. to remove phenol by evaporation or distillation under normal pressure. Method for producing diphenyl acid. 4. From 2 to 500 mmH from the melt in the liquid phase state
The method for producing diphenyl oxalate according to claim 2, wherein phenol is removed by evaporation or distillation under reduced pressure of g.