JP3264154B2 - Preparation of aryl oxalate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aryl oxalate such as diphenyl oxalate by transesterification using a dialkyl oxalate and a phenol (particularly phenol) as starting materials.

More specifically, the present invention provides a transesterification reaction of a dialkyl oxalate with a phenol in the presence of a transesterification catalyst while removing an aliphatic alcohol to obtain a diphenyl oxalate (diphenyl oxalate). Rate: hereinafter also referred to as DPO) and a method for producing an aryl oxalate which produces an aryl oxalate (aryl oxalate) such as an alkyl phenyl oxalate (alkyl phenyl oxalate).

The method of the present invention for producing aryl oxalates (particularly diphenyl oxalate and alkyl phenyl oxalate) by transesterification of dialkyl oxalates is a completely new industrial process. Aryl oxalates such as diphenyl oxalate and alkyl phenyl oxalate are extremely important industrial raw materials in the production of chemicals and the like.

[0004]

2. Description of the Related Art As a method for producing an oxalic acid aryl ester, oxalic acid and phenols have been conventionally subjected to an esterification reaction by directly heating to 100 to 130 ° C. in an organic solvent in the presence of an esterification catalyst. A method for producing a diaryl ester (see Japanese Patent Publication No. 52-43826), a method for producing an aryl oxalate ester by reacting a dialkyl oxalate with a diaryl carbonate (Japanese Patent Publication No. 5-8019 and Japanese Unexamined Patent Application Publication No. Showa 49-
No. 42621) or a method of producing a diaryl oxalate by transesterification of a dialkyl oxalate and an aryl ester of a lower fatty acid (JP-B-56-2541 and JP-B-57-47).
658).

However, the known method for directly esterifying oxalic acid and phenols to produce oxalic acid diaryl esters has a problem that the reaction rate is extremely slow and requires a long time of reaction. It was not a satisfactory method. In addition, the method for producing an aryl oxalate by reacting a dialkyl oxalate with a diaryl carbonate or a lower fatty acid aryl ester cannot easily produce a diaryl carbonate or a lower aliphatic aryl as a raw material, There is a problem that it is difficult to obtain itself because it is quite expensive.In addition, since various by-products are produced in a considerably large amount in addition to the target substance, it is extremely complicated or complicated to isolate the aryl oxalate. There is a problem that a refining process is required, and the production method is not always industrially satisfactory.

[0006]

[Problems to be Solved by the Invention] The inventors of the present application have solved various problems (such as poor productivity and generation of various by-products) of the above-mentioned known production methods. As a result of diligent research on a method of industrially producing phenyl oxalate substantially free of oxalic acid, a dialkyl oxalate ester and phenols were used as starting materials, and a portion where a shelf in a multistage distillation column was installed or packed. Full of things
The inventors have found for the first time that an oxalic acid aryl ester can be produced by conducting a transesterification reaction while removing aliphatic alcohol as a by-product at the charged portion, and completed the present invention.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for preparing a dialkyl oxalate and a phenol on a shelf of a multi-stage distillation column.
The present invention relates to a process for producing an aryl oxalate, wherein a transesterification reaction is carried out in a placed portion or a filled portion of a filler in the presence of a transesterification catalyst while removing a by-product aliphatic alcohol.

In the production method of the present invention, for example, according to the following reaction formulas (1) and (2), a dialkyl oxalate (a) and a phenol (b) are transesterified to form an aryl oxalate (C-1 and c-
2) and an aliphatic alcohol (d). In addition,
In the production method of the present invention, as shown in the reaction formula (3), the alkylaryl oxalate (c-1) undergoes a disproportionation reaction to cause a dialkyloxalate (c-2) and a diaryloxalate (a). The reaction that produces Preferably, the reactions are performed in the liquid phase, and
All are equilibrium reactions, and the equilibrium is extremely biased toward the original system, and the reaction rate is low.

[0009]

Embedded image

In the reaction formulas (1), (2) and (3), R represents an alkyl group having 1 to 10 carbon atoms, and Ar represents
It is a phenyl group which may have various substituents such as an alkyl group having 1 to 6 carbon atoms and an alkoxy group. Examples of the alkyl group having 1 to 10 carbon atoms as R include methyl, ethyl, n-propyl or isopropyl, n-butyl or isobutyl, n-pentyl or isopentyl, n-hexyl or isohexyl, n-octyl or isooctyl, etc. Can be mentioned.

The alkyl group having 1 to 6 carbon atoms, which is a substituent of Ar in the reaction formula, can be selected from the above-mentioned alkyl groups of R. The alkoxy group having 1 to 6 carbon atoms which is a substituent of Ar preferably includes a methoxy group, an ethoxy group, a propoxy group, a butoxy group and the like. Examples of the aliphatic alcohol include methanol, ethanol, propanol, butanol, and hexanol.

In the production method of the present invention, for example, an alkyl aryl oxalate (c
-1) is produced, and according to the reaction formula (2), a diaryl oxalate (c-2) is produced, and according to the reaction formula (3), the alkyl aryl oxalate is converted to the diaryl oxalate (c-2). And a dialkyl oxalate (a) is produced. Therefore, the aryl oxalate, which is the object of the present invention, includes both the alkyl aryl oxalate (c-1) and the diaryl oxalate (c-2), or any of them. is there.

In the production method of the present invention, for example, when dimethyl oxalate (dimethyl oxalate) and phenol are used as raw materials, methyl oxalate (methyl phenyl oxalate) is obtained according to the reaction formula (1). ) And methanol are mainly formed, and furthermore, oxalic acid diphenyl ester (diphenyl oxalate) and methanol are mainly formed according to the reaction formula (2), and further, oxalic acid diphenyl ester and dimethyl are formed according to the reaction formula (3). It produces oxalate.

Therefore, in this case, the reaction solution mainly contains the starting material and the catalyst, methylphenyl oxalate and diphenyl oxalate which are the objective oxalic acid aryl esters, and methyl alcohol which is a by-product. Since other by-products are extremely small, it is easy to separate the target substance.

In the process of the present invention, the ratio of the dialkyl oxalate to the phenol varies depending on the type and amount of the catalyst and the reaction conditions. Phenols are represented by a molar ratio of 0.01 to 1000 times,
In particular, it is preferably about 0.1 to 100 times, and more preferably about 0.5 to 20 times.

The amount of the catalyst used in the production method of the present invention varies depending on the type of catalyst, the type and size of a reactor (eg, a multi-stage distillation column), the type and composition of each raw material, and the reaction conditions for transesterification. Is usually about 0.0001 to 50% by weight, particularly 0.001 to 30% by weight, more preferably 0.005 to 10% by weight, expressed as a ratio to the total amount of dialkyl oxalate and phenols.
It is preferred that it is about.

The reaction conditions for the transesterification in the production method of the present invention are not particularly limited, but in particular, the reaction temperature is about 50 to 350 ° C., and the reaction pressure is 0.00.
The pressure may be 1 mmHg to 200 kg / cm ² and the reaction time may be about 0.001 to 100 hours.

The dialkyl oxalate used in the production method of the present invention has 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms.
More preferably, oxalic acid diester having two esters based on an alkyl group having 1 to 4 carbon atoms is preferable,
For example, dimethyl oxalate, diethyl oxalate, dipropyl oxalate, dibutyl oxalate, dihexyl oxalate, dioctyl oxalate, methyl ethyl oxalate, and the like can be given.

In the present invention, as the dialkyl oxalate, a dialkyl oxalate having an alkyl group having about 1 to 4 carbon atoms can easily remove alcohol by-produced in the transesterification reaction in the production method of the present invention. Therefore, dimethyl oxalate, diethyl oxalate, dipropyl oxalate, and dibutyl oxalate are most preferable.

The phenol used in the production method of the present invention has at least one substituent such as an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group and a halogen atom. Although phenol may be used, phenol can be mentioned as the most preferred. In the present invention, as phenols other than phenol, o-,
alkylphenols such as m- or p-cresol, xylenol (dimethylphenol), dipropylphenol, methylethylphenol, trimethylphenol, tetramethylphenol, ethylphenol, propylphenol, butylphenol, hexylphenol, o-, m- or p -Alkoxyphenols such as hydroxyanisole and ethoxyphenol; halophenols such as p-chlorophenol and 3,5-dibromophenol; o-, m- or p-nitrophenol.

The transesterification catalyst used in the production method of the present invention may be any one capable of producing an alkylaryl oxalate and / or a diaryl oxalate by a transesterification reaction between a dialkyl oxalate and a phenol. Any transesterification catalyst can be used.

In the present invention, the transesterification catalyst is a conventionally known transesterification catalyst which can be used in a transesterification reaction between a carboxylic acid alkyl ester and a phenol, and is a raw material used in the present invention, ie, dialkyl oxalic acid. A transesterification catalyst which is soluble in a melt of an ester or a phenol, or a reaction mixture of the raw materials and / or products thereof, is preferred.

In the present invention, specific examples of the transesterification catalyst include alkali metal, cadmium or zirconium compounds or complexes thereof, lead compounds, copper group metal compounds, iron compounds, zinc compounds, organotin compounds, and the like. The Lewis acid compounds of aluminum, titanium or vanadium can be mentioned, and it is preferable to use at least one soluble transesterification catalyst thereof.

Examples of the alkali metal, cadmium, or zirconium compound or complex include lithium carbonate, dibutylaminolithium, lithium diacetylacetonate chelate, cadmium diacetylacetonate chelate, zirconium diacetylacetonate chelate, and zirconocene. .

Examples of the above-mentioned lead compounds include lead sulfides, lead hydroxides, namites, plumbates, lead carbonates or basic salts thereof, lead salts of organic acids, and carbonates and bases thereof. Organic salts such as tetrabutyl lead, tetraphenyl lead, tributyl lead halogen, triphenyl lead bromo, and triphenyl lead; and alkoxy lead compounds such as dimethoxy lead, methoxy phenoxy lead, and diphenoxy lead. Can be.

Examples of the compounds of the copper group metals include copper salts of organic acids such as copper acetate, copper diacetylacetonate chelate and copper oleate; copper compounds such as butyl copper, dimethoxy copper and copper halide; silver nitrate; Silver, silver compounds such as silver picrate can be mentioned, and as the iron-based compound, iron compounds such as iron hydroxide, iron carbonate, triacetoxy iron, trimethoxy iron, triphenoxy iron, and zinc Examples of the system compound include zinc diacetylacetonate chelate, diacetoxyzinc, dimethoxyzinc, diethoxyzinc, diphenoxyzinc and the like.

As the organotin compound, for example, (P
h) ₄ Sn, (acetoxy) ₄ Sn, (methoxy) ₄ S
n, (ethoxy) ₄ Sn, (phenoxy) ₄ Sn, (M
e) ₃ SnOCOCH ₃ , (Et) ₃ Sn (OCOCH
₃ ), (Bu) ₃ Sn (OCOCH ₃ ), (Et) ₃ S
n (phenoxy), (Me) ₃ SnOCOPh, (P
h) ₃ Sn (methoxy), (Ph) ₃ SnOCOC
H ₃ , (Bu) ₂ Sn (OCOCH ₃ ) ₂ , (Bu) ₂ S
n (methoxy) ₂ , (Bu) ₂ Sn (ethoxy) ₂ ,
(Bu) ₂ Sn (phenoxy) ₂ , (Bu) ₂ SnCl
₂ , (Ph) ₂ Sn (methoxy) ₂ , (Bu) ₂ Sn
O, BuSnO (OH), (Et) ₃ SnOH, (P
h) ₃ SnOH and the like.

Examples of the above Lewis acid compounds of aluminum include Al (halogeno) ₃ , Al (acetoxy) ₃ , Al (methoxy) ₃ , Al (ethoxy) ₃ , and A
l (butoxy) ₃ , Al (phenoxy) _{3 and the} like. Examples of the Lewis acid compounds of titanium include:
For example, Ti (halogeno) ₃ , Ti (acetoxy) ₃ ,
Ti (methoxy) ₃ , Ti (ethoxy) ₃ , Ti (butoxy) ₃ , Ti (phenoxy) ₃ , Ti (halogeno) ₄ , Ti (acetoxy) ₄ , Ti (methoxy) ₄ ,
Ti (ethoxy) ₄ , Ti (phenoxy) _{4 and the} like can be mentioned, and the above-mentioned vanadium Lewis acid compounds include, for example, VO (halogeno) ₃ , VO
(Acetoxy) ₃ , VO (methoxy) ₃ , VO (ethoxy) ₃ , VO (phenoxy) ₃ , and V (halogeno) ₅ .

In the production method of the present invention, the transesterification catalyst is preferably a lithium compound or a complex thereof, a zirconium complex, an organotin compound, a Lewis acid compound of titanium or the like, and particularly preferably an organotin compound or a tin or titanium compound. Lewis acid compounds are optimal.

In the production method of the present invention, the transesterification reaction of dialkyl oxalate or alkylphenyl oxalate with phenol can be carried out while aliphatic alcohol which is a by-product of low boiling point is immediately removed from the reaction solution. If possible, any reaction apparatus may be used.In particular, it is preferable to carry out the transesterification reaction in a reaction solution in a liquid phase in a distillation reaction apparatus while removing aliphatic alcohol as a by-product. Suitable examples of the distillation reactor include a reactor comprising a continuous multi-stage distillation column.

[0031] It said reactor comprising a multi-stage distillation column, physical <br/> theory plate number of at least two or more stages, in particular 5 to 100 stages, a multi-stage distillation column type reaction apparatus is particularly 7 to 50 stages Is preferred.

In the production method of the present invention, examples of the multistage distillation column type reactor include a tray type distillation column using a bubble bell tray, a perforated plate tray, a bubble tray, and the like.
Alternatively, a packed distillation column packed with various packing materials such as Raschig rings, dressing rings, and pole rings can be used, and even a distillation column having both a tray type and a packed type can be used. Can be.

The production method of the present invention is carried out, for example, in a reactor comprising a multi-stage distillation column 1 having a large number of trays 2 as shown in FIG. 1 (particularly in a portion where the shelf 2 of the multi-stage distillation column 1 is installed). ,
While performing the transesterification reaction represented by the above-mentioned reaction formulas (1) and (2) and the reaction formula (3) in the presence of a transesterification catalyst, a low-boiling point product such as a by-product aliphatic alcohol is distilled by distillation. The condensate is condensed through a cooler 4 provided in a withdrawal line connected to the top of the column, and the condensate is returned to the upper part of the multi-stage distillation column by a circulation line 9 (where the reflux ratio is preferably 0 to 20, Particularly preferably 0
It is preferable that a part of the condensate (mainly aliphatic alcohol) condensed in the cooler 4 is removed from the extraction line 6 to the outside of the system.

The raw materials and catalyst used in the production method of the present invention are as follows:
In the multi-stage distillation column, the range of “the shelf at the portion raised by about 1/4 of the whole shelf from the bottom shelf” to “the shelf at the part lowered by about 1/20 of the whole shelf from the top shelf” Inside (more preferably, from the middle shelf to “1/1 of the entire shelf from the top shelf”
(In the range of "the tray of the part lowered by about 0") in the liquid phase from the raw material supply line 5 connected thereto, and the raw material mixture (or the reaction liquid) flows down each of the trays 2 of the distillation part. A transesterification reaction is carried out in each tray portion (distillation portion) while flowing down, and a reaction solution containing a high concentration of aryl oxalate is collected at the bottom of the multi-stage distillation column 1, and the by-produced aliphatic alcohol is removed from each shelf. It is vaporized in the stage 2 and led to the upper plate together with the vapor phase, and as it goes to the upper plate, the aliphatic alcohol is rectified to a higher concentration and removed from the reaction solution.

In the multistage distillation column 1 shown in FIG. 1, the reaction solution is heated while the reaction solution collected at the bottom of the multistage distillation column 1 is circulated through the circulation line 8 by the heater 3 provided in the circulation line 8. The reaction solution containing the target aryl oxalate is withdrawn from the system via the extraction line 7, and the aryl oxalate is separated in a purification step (not shown). Recover.

When the transesterification in the process of the present invention is carried out in a liquid-phase reaction solution while flowing down a multi-stage distillation column, the reaction temperature is controlled by a mixed solution containing each raw material and the reaction product. It is preferable that the reaction temperature is not lower than the temperature at which the reaction solution consisting of the following is melted, and the temperature is such that the target products, alkylaryl oxalate and diaryl oxalate, are not thermally decomposed. In the present invention, the reaction temperature in the transesterification reaction is about 50 to 350 ° C, particularly 100 to 300 ° C,
The temperature is more preferably about 20 to 280 ° C.

The transesterification reaction pressure may be any one of reduced pressure, normal pressure, and pressurized pressure, but it should be a temperature and pressure at which the by-product aliphatic alcohol can be evaporated. For example, if the reaction temperature is about 50 to 350 ° C., particularly 0.01 mmHg to 1
00 kg / cm ² , more preferably 0.1 mmHg to 5
It is preferably about 0 kg / cm ² .

The reaction time of the transesterification reaction (residence time in the distillation column when a multi-stage distillation column is used) varies depending on the reaction conditions, the type of the reaction apparatus and the operating conditions, but the reaction temperature is about 50%. ~ 350 ° C, about 0.01
~ 50 hours, especially 0.02 ~ 10 hours, further 0.05 ~
Preferably, it is about 5 hours.

[0039]

EXAMPLES Examples of the present invention will be specifically described below. Example 1 Phenol, dimethyl oxalate, and tetraphenoxytitanium (TPT) were mixed in a molar ratio of 3: 1 to the bottom (1 liter) of an 50-stage (actual) older show (multistage distillation reaction tower) having a column diameter of 32 mm. : 500 ml of a liquid mixed at a ratio of 0.0002 was charged, and the bottom was heated to about 190 ° C. with a mantle heater to form a reflux state under reduced pressure.

Next, 12 minutes from the top of the Older Show
In the second stage, a liquid having the same composition as above is fed at a flow rate (flow rate) of 300 ml / h, the reflux ratio is set to about 5, and methanol generated from the uppermost portion is continuously extracted. The transesterification reaction was continuously carried out for 10 hours while continuously withdrawing the reaction solution so as to keep the bottom solution volume of the Oldershaw at 500 ml.

In the transesterification reaction in the Oldershaw, the residence time of the reaction solution was about 2 hours. While maintaining the above conditions, the composition of the distillate from the top of the Older Show and the composition of the extract from the bottom were tracked by gas chromatography analysis.

In the transesterification reaction in the above-mentioned Oldershaw, after the compositions of the above-mentioned distillate and the withdrawn liquid have become stable (about 5 hours after the start of the reaction).
The flow rates and compositions (average values) of these liquids up to 10 hours were as follows. Almost 100% of methanol was distilled from the top of the Oldershaw at a flow rate of 27.4 g / h, and from the bottom of the Oldershaw, 54.43% by weight of phenol and 7.09% of dimethyl oxalate were obtained.
% By weight, 22.84% by weight of methylphenyl oxalate,
And a reaction solution containing 15.49% by weight of diphenyl oxalate was withdrawn at 283 g / h.

Example 2 A transesterification reaction was carried out in the same manner as in Example 1 except that the fade position of the raw material (mixture of phenol, dimethyl oxalate and TPT) was changed from the 12th stage of the Older Show to the bottom. Was.

With the compositions of the distillate and the withdrawn liquid being stable, the flow rates and compositions of these liquids were as follows. Almost 10 from the top of the Older Show
0% methanol was distilled at a flow rate of 8.9 g / h, and phenol was 61.26 from the bottom of the Oldershaw.
Wt., Dimethyl oxalate 23.97 wt.%, Methylphenyl oxalate 13.06 wt.%, And diphenyl oxalate 1.46 wt.
h.

Example 3 A stirrer, a thermometer and a 30 cm long Wigrew distillation tube were attached to a 500 ml three-necked flask, and 282 g (3 mol) of phenol and 118 g (1 mol) of dimethyl oxalate were added thereto. 0.98 g of acetylacetonate complex of zirconium as a catalyst
(0.002 mol), and the mixture was heated to 190 ° C. to uniformly dissolve the reaction solution, and transesterification was carried out for 5 hours while maintaining the temperature and removing methanol under normal pressure.

Gas chromatographic analysis of the reaction solution obtained by the above-mentioned transesterification reaction revealed that the reaction solution contained 0.15 mol of dimethyl oxalate, 1.88 mol of phenol, and 0.18 mol of methylphenyl oxalate. It had a composition of 48 moles and 0.37 moles of diphenyl oxalate. That is, the reaction solution has a composition of dimethyl oxalate: 4.8% by weight, phenol: 47.7% by weight, methylphenyl oxalate: 23.3% by weight, and diphenyl oxalate: 24.2% by weight. I was

Example 4 A transesterification reaction was carried out for 5 hours in the same manner as in Example 3 except that 0.002 mol of tetraphenyltin was used instead of zirconium acetylacetonate.

The reaction solution obtained by the above-mentioned transesterification was analyzed by gas chromatography. As a result, the reaction solution was found to contain 0.18 mol of dimethyl oxalate, 1.85 mol of phenol, and 0.18 mol of methylphenyl oxalate. The composition had a composition of 49 mol and 0.33 mol of diphenyl oxalate. The reaction solution was dimethyl oxalate:
It had a composition of 5.9% by weight, phenol: 47.8% by weight, methylphenyl oxalate: 24.3% by weight, and diphenyl oxalate: 22.0% by weight.

Example 5 A transesterification reaction was carried out for 5 hours in the same manner as in Example 3 except that 0.002 mol of potassium carbonate was used instead of zirconium acetylacetonate.

The reaction solution obtained by the above-mentioned transesterification reaction was analyzed by gas chromatography. As a result, the reaction solution was found to contain 0.35 mol of dimethyl oxalate, 2.19 mol of phenol and 0.19 mol of methylphenyl oxalate. 49 moles and 0.16 moles diphenyl oxalate. The reaction solution was dimethyl oxalate:
It had a composition of 11.0% by weight, phenol: 55.0% by weight, methylphenyl oxalate: 23.6% by weight, and diphenyl oxalate: 10.4% by weight.

[0051]

According to the present invention, a dialkyl oxalate (particularly dimethyl oxalate) and a phenol (particularly phenol) are transesterified by a transesterification reaction.
The present invention provides, for the first time, a method for industrially producing an aryl oxalate (particularly diphenyl oxalate) which is important in a chemical reaction. In the production method of the present invention, the types of by-products are smaller than those of conventionally known methods for producing aryl oxalates, and the by-products are substantially only aliphatic alcohols. Is easy to isolate and purify.

[Brief description of the drawings]

FIG. 1 shows an example of a reaction apparatus comprising a multistage distillation column for carrying out the production method of the present invention.

[Explanation of symbols]

 1: Reactor of multi-stage distillation column 2: Plate 3: Heater 4: Cooler 5: Feed line 6: Extraction line (for aliphatic alcohol) 7: Extraction line (for aryl oxalate)

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI // C07B 61/00 300 C07B 61/00 300 (56) References JP-A-59-70641 (JP, A) JP-A-59 -70640 (JP, A) JP 43-2090 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 69/36 C07C 67/03

Claims (3)

(57) [Claims] 1. A part or packing in which a dialkyl oxalate and a phenol are placed on a shelf of a multistage distillation column.
Wherein a transesterification reaction is carried out in a portion filled with the above while removing a by-product aliphatic alcohol in the presence of a transesterification catalyst. 2. Dialkyl oxalate, phenol
, And the transesterification catalyst in the bottom shelf of the multistage distillation column.
From the shelf that is 1/4 of the whole shelf up to the top
Of the part that is 1/20 of the whole shelf below the shelf
Into the enclosure in the liquid phase, and the mixture is allowed to flow downward.
While in the presence of a transesterification catalyst,
Ester removal at each shelf while removing aliphatic alcohol
Aryl oxalate characterized by the reaction
Recipe. 3. A transesterification catalyst comprising an alkali metal, cadmium,
Complex of lead or zirconium, lead compound, iron compound
Substances, copper group compounds, zinc compounds, organotin compounds,
And Lewis acids of aluminum, titanium or vanadium
At least one soluble selected from the group consisting of compounds
3. The catalyst according to claim 1, which is a transesterification catalyst.
Production method of uric acid aryl ester.