JPH09241219A - Production of aromatic carbonic ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain aromatic carbonic esters in a sufficiently high reaction rate without the need of operation to remove byproducts. SOLUTION: A dialkyl carbonic ester of the formula, R-OCOO-R (R is a <=3C alkyl) is reacted with a higher fatty acid carbonic aryl ester of the formula, R'COO-Ar [R' is a >=7C alkyl; Ar is an (alkyl-, alkoxy-, aryl-, aryloxy- or halogen-substituted) phenyl] in the presence of a catalyst to obtain the objective aromatic carbonic esters of the formula, Ar-OCOO-R and the formula, Ar-OCOO-Ar, respectively.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a method for producing an aromatic carbonate. More specifically, the present invention comprises transesterifying a dialkyl carbonate
The present invention relates to a method for producing an aromatic carbonic acid ester. Aromatic carbonates are useful as raw materials 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, phosgene is extremely toxic, the equipment is highly corrosive, and a large amount of alkali is required to neutralize the by-produced hydrogen chloride. And 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-
No. 48733 discloses a method using a tin compound as a catalyst. However, according to the description of the publication, a sufficient yield has not been obtained despite a reaction time as long as 30 hours. In addition, JP-A-57-176932.
JP-A-60-169444, JP-A-56-251
No. 38, Japanese Patent Application Laid-Open No. 1-265064 and the like show similar reactions, but none of them has solved the problem that the reaction speed is slow.

[0005] As a method for improving the reaction rate, JP-A-51-105032 and JP-A-56-123948 are known.
In Japanese Patent Application Laid-Open Publication No. H11-157, 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, in any of these methods, the step of returning to phenyl acetate is complicated, and is not practical. Further, in the conventional method, the reaction distillation is carried out under pressure, and the reaction is carried out while extracting the low-boiling compound (methanol or methyl acetate) together with the raw material dialkyl carbonate, so that the raw material dialkyl carbonate is in the reaction system. There was a problem that it could not be used effectively because it went out. It was also necessary to separate the low boiling point compound and the dialkyl carbonate.

[0007]

SUMMARY OF THE INVENTION In view of these problems, the present invention provides a reactive species which can replace the phenyl acetate and by which the by-produced alkyl ester can be easily converted into the phenyl ester.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that when a higher aliphatic carboxylic acid aryl ester is used in place of phenyl acetate, a low boiling point compound is obtained. It has been found that a sufficient reaction rate can be obtained without extracting and that the resulting carboxylic acid alkyl ester can be easily returned to a phenyl ester, and the present invention has been completed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a dialkyl carbonate represented by the following general formula (1) is reacted with a higher aliphatic carboxylic acid aryl ester represented by the following general formula (2) in the presence of a catalyst. The method for producing an aromatic carbonic acid ester represented by the general formula (3) or the general formula (4) is characterized by:

Embedded image R-OCOO-R (1) R'-COO-Ar (2) Ar-OCOO-R (3) Ar-OCOO-Ar (4) (In the formula, R is an alkyl group having 3 or less carbon atoms. R'is an alkyl group having 7 or more carbon atoms; Ar is an unsubstituted or alkyl group, an alkoxy group, an aryl group, an aryloxy group,
Indicates a phenyl group substituted by halogen)

According to the method of the present invention, by using the higher aliphatic carboxylic acid aryl ester in place of phenol or phenyl acetate, it is possible to obtain the aromatic carbonic acid ester at a sufficient reaction rate without extracting the low boiling point compound. It can be manufactured. Since the boiling point of the higher fatty acid methyl ester or ethyl ester is higher than that of methyl alcohol or ethyl alcohol, it is easy to form an aryl ester while removing these lower alcohols when reacting with an aromatic hydroxy compound.

The present invention will be described in detail below.
Examples of the dialkyl carbonate ester represented by the general formula (1) used in the present invention include dimethyl carbonate ester and diethyl carbonate ester. The higher aliphatic carboxylic acid aryl ester represented by the general formula (2) used in the present invention is an aryl carboxylic acid aryl ester substituted with a halogen or a phenyl group having 8 to 20 carbon atoms. The aryl ester of an aliphatic carboxylic acid having 7 or less carbon atoms is not preferable because it is difficult to separate it from the product. Further, it is not preferable to use an aliphatic carboxylic acid aryl ester having 21 or more carbon atoms because it is difficult to separate the by-produced aliphatic carboxylic acid alkyl ester and the product. Specifically, phenyl octanoate, phenyl nonanoate, phenyl caprate, phenyl undecanoate, phenyl laurate, phenyl tridecanoate, phenyl myristate, phenyl pentadecanoate, phenyl palmitate, phenyl margarate, phenyl stearate,
Phenyl 4-tert-butylcyclohexanecarboxylate,
Examples thereof include phenyl cinnamate, phenyl phenylacetate, phenyl 11-bromoundecanoate, phenyl 10-undecenoate, phenyl oleate, and 3,5-dimethylphenyl octanoate.

The higher aliphatic carboxylic acid aryl ester and the dialkyl carbonic acid ester may be used at any desired molar ratio, but usually 0.1 to 50 mol per mol of the higher aliphatic carboxylic acid aryl ester. On this occasion,
By increasing the molar ratio of the dialkyl carbonate, the intermediate alkyl aryl carbonate can be selectively obtained. Further, if a small amount of the dialkyl carbonate is used for the higher aliphatic carboxylic acid aryl ester, the diaryl carbonate can be obtained. Carbonic acid ester can be selectively obtained. Furthermore, in the case of obtaining a diaryl carbonate, an alkyl aryl carbonate as a reaction intermediate may be added in advance at an arbitrary ratio. Examples of such addition amount are 0.1 to 10 mol, more preferably 0.1 to 1 mol, and further preferably, per 1 mol of the higher aliphatic carboxylic acid aryl ester.
A range of 0.2 to 0.5 mol is selected.

The catalyst used in the present invention is a known transesterification.
Catalysts, ie Lewis acids and protic acids and mixtures thereof
Or a basic compound. As an example of acidic compounds
Is AlX_Three, BX_Three, FeX_Three, SnX_Four, SnOX
_Two, TiX_Three, TiX_Four, UX _Four, VOX_Three, VX_Four,
VX_Five, ZnX_Two, ZnO (where X is halogen or
Alkyl group, aryl group, alkyloxy group, aryl
Is an oxy group), hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, charcoal
Acid, methanesulfonic acid, trifluoromethanesulfone
Acid, toluene sulfonic acid, benzene sulfonic acid and
Examples of the mixture and basic compound include sodium hydroxide.
Lithium, potassium hydroxide, calcium hydroxide, sodium carbonate
Arium, potassium carbonate, disodium phenyl phosphate, etc.
However, it is not limited to these.
Yes. Among these, titanium tetrapheno
Aryl oxides of titanium such as xides are preferred. H
Alkoxides of tan, such as titanium tetraisopro
Poxides can be used, but titanium alkoxides
Included in the present invention when it is converted to an aryl oxide in the system
It is. In addition, titanium tetraaryl oxide
Hydroxy compound and titanium tetrahalide or te
Distillation under high vacuum when synthesizing with traalkoxide
Titanium tetraaryloxy
And adduct of aromatic hydroxy compound are obtained.
However, the use of this adduct does not hinder the reaction.

The amount of the catalyst used in the present invention is an amount generally called a catalytic amount and is not particularly limited, but is usually 0.0001 to 1 mol% relative to the higher aliphatic carboxylic acid aryl ester as a raw material. Used in the range.

The reaction temperature in the present invention is 50 to 300 ° C.
Can be in a wide range, but preferably 90 ~ 240 ℃
It is performed within the range. The reaction can be carried out under either normal pressure or pressure, but when the reaction is carried out at a temperature higher than the boiling point of the starting material, it is generally 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 diaryl carbonate and alkylaryl carbonate can be obtained from the reaction solution obtained by the above-mentioned method by a usual separation operation. The alkylaryl carbonate can be converted to a diaryl carbonate by returning it to the reaction solution as described above and using it as a raw material, or a known disproportionation reaction (for example, described in JP-A-58-48537). Can also be used as a diaryl carbonate.

[0018]

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 In an autoclave made of SUS316 having an internal volume of 100 ml,
Phenyl octanoate 30 g (136.2 mmol), dimethyl carbonate 6.13 g (68.1 mmol), titanium tetraphenoxide 0.17 g (0.41 mmol)
Was charged, the atmosphere was replaced with nitrogen, the vessel was sealed, and the mixture was reacted at 200 ° C. for 2 hours. After the reaction was completed, the reaction solution was analyzed by gas chromatography, and as a result, it was found that phenyl octanoate 70.
It contained 8 mmol, 65.4 mmol of methyl octoate, 23.2 mmol of dimethyl carbonate, 31.3 mmol of methylphenyl carbonate and 13.6 mmol of diphenyl carbonate. And
The by-produced methyl octoate could be easily returned to phenyl octoate by reacting with phenol.

Example 2 In an autoclave made of SUS316 having an internal volume of 100 ml,
Phenyl 4-tert-butylcyclohexane-1-carboxylate 30 g (115.2 mmol), dimethyl carbonate 5.
19 g (57.6 mmol) and 0.15 g (0.35 mmol) of titanium tetraphenoxide were added, and after pressurizing with nitrogen to 5 kg / cm 2, the reaction was carried out at 200 ° C. for 2 hours. After the reaction was completed, the reaction solution was diluted with acetone and analyzed by gas chromatography.
phenyl rt-butylcyclohexane-1-carboxylate 5
7.6 mmol, methyl 4-tert-butylcyclohexane-1-carboxylate 57.6 mmol, dimethyl carbonate 23.6 mm
ol, methyl phenyl carbonate 24.2 mmol, diphenyl carbonate 9.8 mmol. And 4-tert which was a by-product
Methyl -butylcyclohexane-1-carboxylate could be easily converted back to phenyl 4-tert-butylcyclohexane-1-carboxylate by reaction with phenol.

Example 3 In an autoclave made of SUS316 having an internal volume of 100 ml,
Phenyl laurate 30 g (108.5 mmol), dimethyl carbonate 4.90 g (54.4 mmol), titanium tetraphenoxide / phenol adduct 0.17 g
(0.33 mmol) was added thereto, the atmosphere was replaced with nitrogen, the vessel was sealed, and the mixture was reacted at 200 ° C. for 2 hours. After the reaction was completed, the reaction solution was analyzed by gas chromatography. As a result, it was found that the reaction solution contained 62.9 mmol of phenyl laurate and 4 parts of methyl laurate.
5.6 mmol, dimethyl carbonate 20.8 mmol, methylphenyl carbonate 23.9 mmol and diphenyl carbonate 9.8 mmol were included. Then, the by-produced methyl laurate could be easily returned to phenyl laurate by reacting with phenol.

Example 4 In an autoclave made of SUS316 having an internal volume of 100 ml,
Phenyl laurate 30 g (108.7 mmol), dimethyl carbonate 3.35 g (37.2 mmol), methylphenyl carbonate 5.21 g (34.3 mmol), titanium tetraphenoxide 0.14 g (0.33 mmol)
Was charged, the atmosphere was replaced with nitrogen, the vessel was sealed, and the mixture was reacted at 200 ° C. for 2 hours. After completion of the reaction, the reaction solution was analyzed by gas chromatography. The results are shown in Table 1.

[0023]

[Table 1]

[0024]

EFFECTS OF THE INVENTION According to the present invention, an aromatic carbonate ester can be produced at a sufficient reaction rate without the operation of removing the low boiling point compound. In addition, since the carboxylic acid alkyl ester produced as a by-product can be converted into an aryl ester by reacting with an aromatic hydroxy compound, an aromatic carbonate ester can be easily produced as a whole, and its industrial effect is great. .

Claims (3)

[Claims] 1. A dialkyl carbonate represented by the following general formula (1) is reacted with a higher aliphatic carboxylic acid aryl ester represented by the following general formula (2) in the presence of a catalyst. , General formula (3) and general formula (4)
A method for producing an aromatic carbonic acid ester represented by. R-OCOO-R (1) R'-COO-Ar (2) Ar-OCOO-R (3) Ar-OCOO-Ar (4) (In the formula, R is an alkyl group having 3 or less carbon atoms. R'is an alkyl group having 7 or more carbon atoms; Ar is an unsubstituted or alkyl group, an alkoxy group, an aryl group, an aryloxy group,
Indicates a phenyl group substituted by halogen) 2. A catalyst comprising Ti (OA'r) ₄ or Ti
The manufacturing method according to claim 1 or 2, wherein an adduct of (OA'r) ₄ and A'rOH is used. (Where
A'r is an unsubstituted group, an alkyl group, an alkoxy group,
Aryl group, aryloxy group, phenyl group substituted with halogen) 3. The production method according to claim 1, wherein Ar and A′r are phenyl groups.