JPH09124560A - Method for producing aromatic carbonate - Google Patents

Abstract

(57) Abstract: A method for efficiently producing an aromatic carbonic acid ester from a dialkyl carbonic acid ester and an aromatic carboxylic acid aryl ester is provided. SOLUTION: In the presence of a transesterification catalyst, the general formula R-
A dialkyl carbonic acid ester represented by OCOO-R is reacted with an aromatic carboxylic acid aryl ester represented by the general formula Ar-COO-Ar '. [Effect] An aromatic carbonic acid ester can be produced at a sufficient reaction rate without requiring a complicated reaction step.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aromatic carbonic acid ester. More specifically, the present invention relates to a method for producing an aromatic carbonic acid ester having at least one aromatic group by transesterifying a carbonic acid dialkyl ester. Aromatic carbonic acid ester is a compound useful as a raw material for melt transesterification polycarbonate.

[0002]

2. Description of the Related Art Aromatic carbonic esters have hitherto been produced by reacting an aromatic hydroxy compound with phosgene. However, because phosgene is highly toxic, the equipment is highly corrosive, and a large amount of alkali is required to neutralize by-produced hydrogen chloride, a method that does not use phosgene has been demanded. , Several attempts have been made.

For example, there has been proposed a method of oxidatively carbonylating an aromatic hydroxy compound and carbon monoxide as raw materials. However, these methods use expensive palladium as a main catalyst and require a cocatalyst, a desiccant, an oxidizing agent, and the like, so that the reaction system is very complicated. In addition, it is difficult to recover the catalyst, and the present situation is that the yield and the reaction rate have not reached the industrial level.

[0004] As another production method, a transesterification reaction between an aromatic hydroxy compound and an aliphatic carbonate is known. For example, Japanese Patent Publication No. 56-42577 discloses a method using a Lewis acid as a catalyst.
No. 73016 discloses a method using a mixture of a Lewis acid and a protonic acid as a catalyst. However, in each case, the reaction requires a long time of 5 to 24 hours, and the yield is not sufficient. In addition, JP-A-54-
In Japanese Patent No. 48733, a method using a tin compound as a catalyst is presented, but according to the description in the official gazette, a sufficient yield has not been obtained despite the reaction time of 30 hours. In addition, JP-A-57-176932.
JP, JP-A-60-169444, JP, JP-A-56
No. 25138, JP-A No. 1-265064 and the like show similar reactions, but none of them has solved the problem of slow reaction rate.

As a method for improving the reaction rate, JP-A-51-105032 and JP-A-56-1239 are known.
No. 48, it is proposed to use phenyl acetate instead of phenol. However, in this method, despite the use of expensive phenyl acetate, the use of by-produced methyl acetate was not shown.

As a method for improving this, US Pat. No. 4,533,504 proposes a method in which methyl acetate is used as ketene, and this is returned to phenyl acetate as a raw material by reacting this with phenol. . Similarly, JP-A-5-507060 describes a method of reacting methyl acetate with carbon monoxide to produce acetic anhydride, and reacting this with phenol to return it to phenyl acetate. However, it is difficult to say that any of these methods is practical because the step of returning to phenyl acetate is complicated.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an aryl ester of an alkyl ester produced by using an aromatic carboxylic acid aryl ester as a reactive species in place of phenyl acetate. It is intended to provide a method that can be easily converted to an ester.

[0008]

As a result of studying the above problems, the present inventors have found that by using an aromatic carboxylic acid aryl ester as a reactive species in place of phenyl acetate,
The present invention has been made by discovering that the reaction rate is considerably higher than that of the conventional method without producing a low-boiling compound as a by-product and that the by-produced alkyl ester can be easily converted into an aryl ester.

That is, according to the present invention, a dialkyl carbonic acid ester represented by the following general formula (1) and an aromatic carboxylic acid aryl ester represented by the general formula (2) are reacted in the presence of a transesterification catalyst. It is a method for producing an aromatic carbonic acid ester, which is characterized by carrying out.

[0010]

Embedded image R—OCOO—R (1) Ar—COO—Ar ′ (2) (In the formula, R is a C ₁ -C ₄ alkyl group, Ar, Ar ′.
Represents an unsubstituted or substituted phenyl group substituted with an alkyl group, an alkoxy group, an aryl group, an aryloxy group or a halogen. These may be the same or different)

Further, the present invention provides (a) the above general formula (1)
And a dialkyl carbonate ester represented by the above general formula (2)
A step of reacting an aromatic carboxylic acid aryl ester represented by the following in the presence of a transesterification catalyst to produce a diaryl carbonate, and (b) a formula represented by the following general formula (3) obtained in the above step (a) Reacting the aromatic carboxylic acid alkyl ester with an aromatic compound having a hydroxyl group in the presence of a transesterification catalyst to produce an aromatic carboxylic acid aryl ester represented by the general formula (2), and (C) A method for producing a carbonic acid ester, which comprises the step of using the aromatic carboxylic acid aryl ester as a part of the reactant in the step (a).

[0012]

Embedded image Ar—COO—R (3) (In the formula, R and Ar represent the same as above)

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is to produce an aromatic carbonic acid ester by reacting a dialkyl carbonic acid ester with an aromatic carboxylic acid aryl ester in the presence of a transesterification catalyst.

The catalysts used in the present invention are acidic compounds of Lewis acids, protic acids and mixtures thereof. As these acidic compounds, AlX ₃ , BX ₃ , FeX ₃ ,
SnX _3, SnOX ₃ , Y (acac) ₃ , UX ₄ , VOX
₃ , VX ₃ , VX ₅ , ZnO, ZnX _2, GaX ₃ (wherein, X is a halogen or an alkyl group, an aryl group, an alkyloxy group or an aryloxy group), other hydrochloric acid, bromide Examples thereof include inorganic acids such as hydrogen acid, sulfuric acid and phosphoric acid, organic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, toluenesulfonic acid and benzenesulfonic acid, or a mixture thereof.

Among those described above, the catalyst containing aluminum, gallium and tin is particularly effective. Further, if desired, a basic compound such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate or disodium phenylphosphate can be mixed with the above acid-forming compound and used.

In the present invention, the alkoxide of the metal compound shown above is one in which an alkoxy group is directly bonded to a metal, and specifically, for example, aluminum trimethoxide, aluminum triethoxide, aluminum tri-n-propoxy. Aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum tri-sec-butoxide, aluminum tri-t.
ert-butoxide, gallium trimethoxide, gallium triethoxide, gallium tri-n-propoxide,
Gallium triisopropoxide, gallium tri-n-butoxide, gallium tri-sec-butoxide, gallium tri-tert-butoxide, di-n-butyldimethoxytin, di-n-butyltin-n-butoxide, tri-n- Butyltin ethoxide, tri-n-butyltin methoxide and the like can be mentioned.

The aryl oxide of the metal compound is
A metal in which an aryloxy group is directly bonded, specifically, for example, aluminum triphenoxide, aluminum tri (4-methylphenoxide), aluminum tris (2,4-dimethylphenoxide),
Aluminum tris (3,5-dimethylphenoxide), aluminum tri (4-methoxyphenoxide), aluminum tri (4-chlorophenoxide),
Gallium tri (4-methylphenoxide), gallium tris (2,4-dimethylphenoxide), gallium tris (3,5-dimethylphenoxide), gallium tri (4-methoxyphenoxide), gallium tri (4-chlorophenoxide), di Examples thereof include -n-butyldiphenoxytin and tri-n-butylphenoxide.

The term "tin dialkyl oxide" as used in the present invention means a compound in which an alkyl group is directly bonded to a tin oxide, and examples thereof include, for example, di-n-butyltin oxide and di-n-propyltin oxide. , Diethyl tin oxide, dimethyl tin oxide and the like.

In the present invention, the amount of the catalyst used is generally a so-called catalytic amount, and the desired amount is not particularly limited, but it is usually 1 mol of the aromatic carboxylic acid aryl ester as the raw material. Used in the range of 0.0001 to 1 mol%.

The amount of the dialkyl carbonic acid ester with respect to the aromatic carboxylic acid aryl ester can be used in an arbitrary ratio, but usually 0.2 to 50 mol is suitable per 1 mol of the aromatic carboxylic acid aryl ester. At this time, by increasing the molar ratio of the dialkyl carbonate, an alkylaryl carbonate as an intermediate can be selectively obtained. Further, when the purpose is to obtain a diaryl carbonate, an alkyl carbonate ester as a reaction intermediate can be added in advance. The addition amount of the alkylaryl carbonate is used at an arbitrary ratio, but it is convenient that the change in the concentration of the alkylaryl carbonate before and after the reaction is small. As an example of such an addition amount, 0.1 to 10 mol, preferably 0.1 to 1 mol, per 1 mol of the aromatic carboxylic acid aryl ester,
Further, 0.2 to 0.5 mol is preferable.

The aromatic carboxylic acid aryl ester represented by the general formula (2) in the present invention is, for example,
Phenyl benzoate, phenyl o-, m- or p-methyl benzoate, phenyl 2,4-dimethyl benzoate 3,
Phenyl 5-dimethylbenzoate, phenyl 4-n-propylbenzoate, phenyl 4-isopropylbenzoate, 4
Phenyl-n-butylbenzoate, phenyl 4-isobutylbenzoate, phenyl 4-sec-butylbenzoate, 4
Phenyl-tert-butylbenzoate, phenyl 4-methoxybenzoate, phenyl 4-phenylbenzoate, 4-
Phenyl phenoxybenzoate, phenyl 4-chlorobenzoate, 4-phenyl 2-6-dichlorobenzoate, o-
4-chlorophenyl methylbenzoate, 4-phenoxyphenyl 2,6-dimethylbenzoate and the like can be mentioned.

The specific embodiment of the present invention is not particularly limited, but a dialkyl carbonic acid ester, an aromatic carboxylic acid aryl ester and the above catalyst are charged into a reactor,
By reacting, an aromatic carbonate, that is, an alkylaryl carbonate and a diaryl carbonate can be obtained. This reaction can be performed by either a batch method or a continuous method.

The reaction temperature in the present invention is 50 ° C to 300 ° C.
A wide range of ℃ is possible, but preferably 90 ℃ ~ 24
It is performed in the range of 0 ° C. The reaction can be carried out under either atmospheric pressure or pressure, but when it is carried out at a temperature higher than the boiling point of the starting material, it is preferably carried out under pressure. Although the reaction time varies depending on other conditions, it is generally several minutes to several tens hours, preferably 30 minutes to 6 hours.

In carrying out the present invention, a solvent inert to the reaction can be used, or the reaction can be carried out in the presence of an inert gas or under pressure with an inert gas. Needless to say, each of the raw materials used in the present invention is preferably pure.

The desired aromatic carbonate ester can be obtained from the reaction solution obtained by the above-mentioned method by a usual separation operation. It is also possible to return the alkylaryl carbonate to the reaction solution as described above and use it as a raw material to obtain a diaryl carbonate. Also,
For example, a diaryl carbonate ester may be obtained by a disproportionation reaction known per se as described in JP-B-58-48537.

[0026]

EXAMPLES The method of the present invention will be described with reference to the following examples, but the present invention is not limited to these examples.

Example 1 30 g (151 mmol) of phenyl benzoate, 6.82 g (75.7 mmol) of dimethyl carbonate and 0.38 g (1.51 mmol) of gallium triisopropoxide were placed in an autoclave made of SUS316 having a capacity of 100 ml, and nitrogen was added. After pressurizing to 20 kg / cm @ 2, the reaction was carried out at 150 DEG C. for 2 hours. After completion of the reaction, the reaction solution was diluted with acetone and then analyzed by gas chromatography. As a result, the conversion rate of phenyl benzoate was 48%, the yield of methylphenyl carbonate was 25%, and the yield of diphenyl carbonate was 20%.

Examples 2 to 5 The same experiment as in Example 1 was carried out except that 1.51 mmol of the catalyst shown in the table was used instead of gallium triisopropoxide. The results are shown in the table.

[0029]

[Table 1] Table-1 Examples Catalyst conversion MPC yield DPC yield ─────────────────────────────── 1 Ga (OiPr) ₃ 48% 25% 20% 2 Al (OEt) ₃ 40% 23% 15% 3 Sn (nBu) ₂ (OMe) ₂ 24% 14% 7% 4 SnO (nBu) ₂ 18% 11% 4% 5 Y (acac) ₃ 18% 11% 4% (Note) Conversion rate: conversion rate of phenyl benzoate MPC: methylphenyl carbonate DPC: diphenyl carbonate (same for comparative examples)

Comparative Examples 1 to 14 The same experiment as in Example 1 was carried out except that 1.51 mmol of the catalyst shown in Table 2 was used instead of gallium triisopropoxide. The results are shown in the table.

[0031]

[Table 2] Table-2 Comparative Examples Catalyst conversion MPC yield DPC yield ───────────────────────────────── 1 VO (OiPr) 3 10% 3% 0% 2 Y (OAc) 3 9% 0% 0% 3 Na2CO3 9% 0% 0% 4 Zr (OEt) 4 9% 4% 0% 5 Zn (OnPr) 2 6% 0% 0% 6 Sb (OiPr) 3 5% 3% 0% 7 NaOMe 5% 0% 0% 8 Sr (OiPr) 2 3% 0% 0% 9 TiO2 2% 0% 0% 10 In (OiPr ) 3 1% 0% 0% 11 Ge (OiPr) 4 0% 0% 0%

Example 6 30 g (151 mmol) of phenyl benzoate, 6.82 g (75.7 mmol) of dimethyl carbonate and 0.38 g (1.51 mmol) of di-n-butyltin oxide were placed in an autoclave made of SUS316 having an internal capacity of 100 ml. After pressurizing with nitrogen to 20 kg / cm ² , the reaction was carried out at 180 ° C. for 3 hours. After completion of the reaction, after diluting the reaction solution with acetone,
It was analyzed by gas chromatography. As a result, the conversion rate of phenyl benzoate was 41% and the yield of methylphenyl carbonate was 18%.
%, And the yield of diphenyl carbonate was 21%.

[0033]

Industrial Applicability According to the present invention, an aromatic carbonate ester can be produced from a dialkyl carbonate ester in a good yield, and its industrial significance is great.

Claims (3)

[Claims] 1. A dialkyl carbonate represented by the following general formula (1) and an aromatic carboxylic acid aryl ester represented by the general formula (2) are reacted in the presence of a transesterification catalyst. And a method for producing an aromatic carbonate ester. Embedded image R—OCOO—R (1) Ar—COO—Ar ′ (2) (In the formula, R is a C _{1 to} C ₄ alkyl group, Ar, Ar ′.
Represents an unsubstituted or substituted phenyl group substituted with an alkyl group, an alkoxy group, an aryl group, an aryloxy group or a halogen. These may be the same or different) 2. (a) A dialkyl carbonic acid ester represented by the general formula (1) and an aromatic carboxylic acid aryl ester represented by the general formula (2) are reacted in the presence of a transesterification catalyst. To produce a diaryl carbonate,
(B) The aromatic carboxylic acid alkyl ester represented by the following general formula (3) obtained in the above step (a) is reacted with an aromatic compound having a hydroxyl group in the presence of a transesterification catalyst to produce the above general compound. A step of producing an aromatic carboxylic acid aryl ester represented by the formula (2), and (c) a step of using the aromatic carboxylic acid aryl ester as a part of the reactant in the step (a). A method for producing a carbonic acid ester, which is characterized. [Image Omitted] Ar-COO-R (3) (In the formula, R and Ar represent the same as above) 3. A dialkyl carbonate represented by the general formula (1) and an aromatic carboxylic acid aryl ester represented by the above (2) are reacted in the presence of a transesterification catalyst. A method for producing an alkylaryl carbonate represented by the following general formula (4). Embedded image Ar ′ —OCOO—R (4) (wherein Ar ′ and R are the same as above)