JPH0733714A - Method for producing aromatic carbonic acid ester - Google Patents

Abstract

PURPOSE:To provide a process for efficiently producing an aromatic carbonic acid ester from a phenolic compound or its acyl ester and a carbonic acid ester having at least one alkyl group. CONSTITUTION:An aromatic carbonic acid ester can be produced by reacting a phenolic compound or its acyl ester with a carbonic acid ester having at least one alkyl group in the presence of a catalyst expressed by the formula Fe(OC6H5)3.

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 aromatic carbonic acid ester useful as a monomer for producing a polycarbonate.

[0002]

2. Description of the Related Art The following methods are known as conventional methods for producing aromatic carbonic acid esters. (I) Phosgene Method In this method, phenol and phosgene are reacted in the presence of an alkali to obtain an aromatic carbonate ester. (Ii) Oxidative carbonylation method of phenol In this method, an aromatic carbonic acid ester is obtained by bringing phenol into contact with a CO-O ₂ mixed gas in the presence of a catalyst system containing Pd (JP-A-2-104564). No. 2-1
No. 42754, No. 1-165551 and U.S. Pat. No. 450442).

However, since the method (i) uses toxic phosgene, it must be carefully considered in terms of safety, and the neutral salt (for example, NaCl) produced as a by-product of the reaction can be removed. It has the drawback of having to be processed. In addition, the method (ii) is disadvantageous in that sufficient consideration must be given to safety because it uses CO, which is a toxic gas, and there is a risk of explosion of CO-O ₂ mixed gas. There is a drawback that both the over and the yield are extremely low.

In order to solve the above-mentioned drawbacks (i) and (ii), an aliphatic carbonate ester such as dimethyl carbonate, which is advantageous from the viewpoint of safety, is used as a carbonyl source, and this is reacted with phenol to give an aroma. Transesterification methods have been developed to obtain group carbonate esters. If this transesterification method is combined with an efficient method for removing alcohol by-produced in the reaction, an aromatic carbonate ester can be obtained with extremely high efficiency.

This transesterification method is usually carried out in the presence of a catalyst, and the following catalysts have been conventionally known as catalysts to be used. (A) Organic titanium or aluminum compound catalysts represented by TiX ₄ or AlX ₃ (X = alkoxy group or aryloxy group) (Japanese Patent Publication Nos. 59-34170 and 56-42577) (b) SnR ₂ (OC ₆ H ₅ ) ₂ (R = alkyl group) -based organotin compound catalyst (Japanese Patent Laid-Open No. 54-4873)
No. 3) (c) Zr (acac) ₄ or Fe (acac)
Metal chelate catalyst represented by ₃ (acac = acetylacetone ligand) or a catalyst obtained by adding acetylacetone as a co-catalyst to this catalyst (Japanese Patent Publication No. 1-5588) (d) Pb (OH) ₂ .2PbCO ₃ etc. Lead compound catalyst (Japanese Patent Publication No. 1-3181) (e) Fe (OAc) ₃ as a main component
A catalyst containing ₃ , Mn, Na and H ₂ O (Japanese Patent Laid-Open No. 61-
In addition, in Japanese Patent Laid-Open No. 51-105032, Al
X ₃ , UX ₃ , TiX ₃ , TiX ₄ , VOX ₃ , V
X ₃ , ZnX ₂ , FeX ₃ , SnX ₄ (X = halogen,
Acetoxy, alkoxy, and the Lewis acid catalyst comprising aryloxy at a) are disclosed, FeX ₃ is only being merely illustrative, the same patent publication FeX ₃
There are no examples using.

[0006]

However, the above catalysts (a) to (e) have the following drawbacks. That is,
The catalyst (a), especially the titanium-based catalyst, has a high catalytic activity, but since it has a low vapor pressure, it is mixed in the aromatic carbonate ester of the product, and the aromatic carbonate ester, and thus the polycarbonate obtained therefrom, is colored reddish orange. There is a problem that causes.

The above catalyst (b) has the same catalytic activity as the titanium catalyst, but has a drawback that a large amount of by-products are likely to be produced. Further, this catalyst (b) also has a drawback that it has a low vapor pressure and is difficult to separate from the product.

The above-mentioned catalyst (c) has the disadvantages that it has a low catalytic activity, the reaction rate cannot be increased, and a large amount of by-products derived from acetylacetone existing in or produced in the system is produced.

Since the catalyst (d) cannot increase the reaction rate and is basic, it has a drawback that it causes the decomposition of the starting material alkyl carbonate or the intermediate or product alkylaryl carbonate. .

The above-mentioned catalyst (e) is a substance which is unstable in properties, is not commercially available as such, and has the drawback that its preparation and storage are difficult.

Therefore, the object of the present invention is to eliminate the drawbacks of the above-mentioned catalysts (a) to (e) used in the production of aromatic carbonic acid ester by the transesterification method, and to achieve the same reaction rate as when using a titanium catalyst. The desired product can be obtained. The desired product is not colored. It has a ligand that does not cause the formation of by-products in the reaction system. Does not cause decomposition of the starting materials, intermediates and carbonates of the desired product. Easy to obtain, stable and easy to handle. It is an object of the present invention to find a new catalyst having advantages such as the above and to provide a method capable of efficiently producing an aromatic carbonic acid ester using this catalyst.

[0012]

As a result of studies for achieving the above object, an organoiron compound represented by the formula Fe (OC ₆ H ₅ ) ₃ (I) has all of the above-mentioned advantages, It was found that an aromatic carbonic acid ester can be efficiently produced when it is used as a catalyst in the production of an aromatic carbonic acid ester according to.

The present invention has been completed based on this finding, and comprises phenols or acyl esters thereof,
A process for producing an aromatic carbonic acid ester, which comprises reacting with a carbonic acid ester having at least one alkyl group in the presence of a catalyst represented by the formula Fe (OC ₆ H ₅ ) ₃ (I). Use as a summary.

The present invention will be described in detail below. In the method for producing an aromatic carbonic acid ester of the present invention, phenol or its acyl ester and carbonic acid ester having at least one alkyl group are used as raw materials.

[0015] As here phenols, compounds of the formula _{Y n -C 6 H 5-n} -OH (II) are preferred.

In the formula (I), Y is a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ alkoxy group, a halogen atom, a cyano group or a nitro group, n is an integer of 0 to 5, and n is When 2 or more, 2 or more Y may be the same or different.

Preferred compounds of formula (I) are phenols in which n is 0 and cresols in which n is 1,
t-Butylphenol, methoxyphenol, chlorophenol, cyanophenol, nitrophenol and the like are preferable.

[0018] As also acyl esters of phenols can be used a compound represented by the formula _{Y n -C 6 H 5-n} -OCO-R (III).

In formula (III), Y and n are the same as in formula (II), and R is a C ₁ -C ₃ alkyl group.
Preferred compounds of formula (III) are those in which n is 0 (Y
Is absent), acetyl ester of phenol in which R is a methyl group, and n is 1 (Y is 1),
Acetyl esters of mono-substituted phenols such as cresol, t-butylphenol, methoxyphenol, chlorophenol, cyanophenol and nitrophenol, in which R is a methyl group, are preferred.

On the other hand, another raw material of at least 1
A preferred example of the carbonic acid ester having 4 alkyl groups is a dialkyl carbonic acid ester represented by the formula R ¹ —OCOO—R ² (IV).

In the formula (IV), R ¹ and R ² are C ₁
To C ₆ alkyl groups, which may be the same or different. Particularly preferred compounds of formula (IV) are dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-n-carbonate.
The carbonic ester having at least one alkyl group is a butyl, can also be used monoalkyl monoaryl carbonate ester represented by the formula ^{Ar-OCOO-R 3 (V} ).

In the formula (V), R ³ is a C ₁ -C ₆ alkyl group, Ar is a group represented by the formula Y _n --C ₆ H _5-n- , and Y and n are the above formulas (II ) And (III).

Preferred compounds of formula (V) are R ³
Is a methyl group, and n in Ar is 0 (that is, Y is 0).
Phenylmethyl carbonate, R ³ is a methyl group, and n in Ar is 1 (that is, Y is 1), cresylmethyl carbonate, t-butylphenylmethyl carbonate, methoxyphenylmethyl carbonate, chlorophenylmethyl carbonate. , Cyanophenylmethyl carbonate, nitrophenylmethyl carbonate and the like.

In the method of the present invention, the ratio of the starting phenols or their acyl esters to the carbonic acid ester having at least one alkyl group is 1 mol of the latter carbonic acid ester and the former phenols or their acyl ester. Is 2 to 10 mol, preferably 4 to
It is 8 mol.

The present invention provides an iron compound-based catalyst represented by the formula Fe (OC ₆ H ₅ ) ₃ (I) in the reaction of the above-mentioned phenols or their acyl esters with carbonic acid esters having at least one alkyl group. It is characterized by using.

Fe (O) of the iron compound catalyst used in the present invention
C ₆ H ₅ ) ₃ can be easily obtained in stable form from Fe (OCH ₃ ) ₃ and excess phenol. In the present invention, the iron compound-based catalyst is 10 ^{-4 to} 1 mol, preferably 10 ^-3 to 10 ^-1 m based on 1 mol of the starting carbonate ester.
ol used. In the method of the present invention, the reaction temperature is not critical, but it is preferably 100 to 250 ° C., particularly 1
50-200 degreeC is preferable.

The reaction system may be either a batch system or a system for removing by-product alcohol such as reactive distillation. However, since this reaction is a reaction in which the equilibrium is extremely biased toward the raw material side, the aromatic carbonate ester of the product is collected. In order to obtain it efficiently, it is necessary to remove the by-product alcohol and shift the equilibrium of the reaction to the product side. The method of removing the by-product alcohol is not particularly limited, but a method of removing the by-product alcohol by distillation at the same time as the reaction is generally adopted. However,
When dimethyl carbonate (DMC) is used as the carbonic acid ester as a raw material, this is by-product methanol (MeOH) and DMC.
/ MeOH = 30/70 (wt / wt) with a composition of 63.
Since it has an azeotropic point of 5 ° C., a part of the raw material dimethyl carbonate is distilled off together with methanol without being used in the reaction (Japanese Patent Publication No. 56-42577, JP-A-3-29).
1257). Therefore, a method of removing only methanol using an entrainer of n-heptane, benzene, etc. has been proposed (see JP-A-54-48732 and JP-A-61-291545), and this method is also applied to the present invention. it can.

According to the method of the invention, the as carbonate raw material, in the case of using a dialkyl carbonate represented by the formula (IV), as the target product, the formula _{Y n -C 6 H 5-n} - OCOO-R ¹ (VI) and / or formula _{Y n -C 6 H 5-n} -OCOO-C 6 H 5-n -Y n (VII) ( wherein (VI), Y in (VII), n, R ¹ is as described above.), And the aromatic carbonate ester represented by the above is obtained. For example, when dimethyl carbonate is used as a raw material carbonic acid ester and this is reacted with phenol, the target product is phenylmethyl carbonate and / or C ₆ H ₅ represented by the formula CH ₃ —OCOO—C ₆ H ₅ (VIa). diphenyl carbonate represented by _{-OCOO-C 6 H 5 (VIIa} ).

When a monoalkyl monoaryl carbonate represented by the formula (V) is used as the starting carbonate, a diaryl carbonate represented by the above formula (VII) is obtained. For example, using phenylmethyl carbonate,
When this is reacted with phenol, the above formula (VII
The diphenyl carbonate shown in a) is obtained.

[0030]

The present invention will be further described with reference to the following examples. Example 1 10 equipped with a Jimroth condenser and a two-way cock
47.06 g of phenol (50
0 mmol), 1.675 g of Fe (OC ₆ H ₅ ) ₃ (5
(mmol) and the system was replaced with nitrogen. Then 1 in advance
The flask was immersed in an oil bath adjusted to 50 ° C. and kept at that temperature. Approximately 20 minutes later, when the temperature in the system became constant at 148 ° C, dimethyl carbonate 11.2 was fed from the two-way cock.
6 g (125 mmol) were introduced by ziringe. Introduction 5
The reaction was started for a predetermined period of time, which was minutes later. The temperature inside the system was 147 ° C. throughout. On the way, when the reaction solution was sampled, it was analyzed by gas chromatography using a two-way cock. One hour after the start of the reaction, phenylmethyl carbonate (PMC) was formed at 8.65 mmol and diphenyl carbonate (DPC) was formed at 0.65 mmol, and the equilibrium was reached. No coloration was observed on the product. No by-products such as anisole were found.

Comparative Examples 1 to 7 As catalysts, instead of Fe (OC ₆ H ₅ ) ₃ , Ti (OC ₆ H ₅ ) ₄ (Comparative Example 1) corresponding to the above conventional catalyst (a) and conventional catalyst (c) were used. ) Equivalent to Zr (acac)
₄ (Comparative Example 2), Zr (OC ₆ H ₅ ) ₄ (Comparative Example 3),
Conventional _{Sn (n-C 4 H 9} ) corresponding to the catalyst (b) ₂ (O
C ₆ H ₅ ) ₂ (Comparative Example 4), Pb (OH) ₂ .2PbCO ₃ corresponding to the conventional catalyst (d) (Comparative Example 5), and basic Fe (OAc) ₃ (corresponding to the conventional catalyst (e). Comparative Example 6), and Fe (aca corresponding to the conventional catalyst (c)
c) The reaction was performed in the same manner as in Example 1 except that ₃ (Comparative Example 7) was used. The results are shown in Table 1 together with the results of Example 1.

[0032]

[Table 1]

As is clear from Table 1, Fe (OC ₆ H
₅ ) In Example 1 using ₃ , it was possible to obtain a target product without coloring without producing a by-product in a short reaction time. On the other hand, in Comparative Example 1 in which Ti (OC ₆ H ₅ ) ₄ was used, the target product was colored. Also Zr
In Comparative Example 2 using (acac) ₄ , not only the reaction rate was slow, but a large amount of by-products such as acetylacetone were produced. In Comparative Example 3 using Zr (OC ₆ H ₅ ) ₄ , not only the reaction rate was slow, but formation of an by-product anisole was observed. In Comparative Example 4 using the Sn-based catalyst,
Contamination of the catalyst into the product was observed. Pb (OH) ₂
In · 2PbCO ₃ Comparative examples using 5, anisole by-product was observed such as methanol, also dimethyl carbonate with time (DMC) was decomposed. The target product PMC decomposed with the lapse of time, and the amount thereof decreased. Basic Fe
In Comparative Example 6 using (OAc) ₃ , not only the reaction rate was slow, but also the yield of the target product was remarkably low. Further, in Comparative Example 7 using Fe (acac) ₃ , the reaction rate was remarkably slow and various by-products were produced.

Example 2 Phenol 47.06 was placed in a 100 ml three-necked flask equipped with a rectification column (total length: 10 cm) filled with a heli pack.
g (500 mmol), Fe (OC ₆ H ₅ ) ₃ 1.67
5 g (5 mmol) was added and the system was replaced with nitrogen. Then, it was immersed in an oil bath adjusted to 150 ° C. in advance and kept at that temperature. When the temperature in the system became constant, 19.02 g (125 mmol) of phenylmethyl carbonate was introduced. Then, the reaction was carried out for 6 hours while distilling off the methanol produced at a reflux ratio of 100. During this time, the temperature in the system changed to 148 to 182 ° C. When the reaction solution obtained after the reaction was analyzed by gas chromatography,
52.3 mmol of diphenyl carbonate was produced.

[0035]

INDUSTRIAL APPLICABILITY According to the present invention, by using an iron compound catalyst represented by the formula Fe (OC ₆ H ₅ ) ₃ (I), phenols or acyl esters thereof and at least one alkyl group can be prepared. An aromatic carbonic acid ester can be efficiently produced from the carbonic acid ester that it has.

Claims (5)

[Claims] 1. Reacting a phenol or an acyl ester thereof with a carbonic acid ester having at least one alkyl group in the presence of a catalyst represented by the formula Fe (OC ₆ H ₅ ) ₃ (I). A method for producing an aromatic carbonic acid ester, comprising: 2. A phenol is represented by the formula Y _n —C ₆ H _5-n —OH (II) (wherein Y is a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkoxy group, a halogen atom, a cyano group). A group or a nitro group,
n is an integer of 0 to 5, and when n is 2 or more, Ys of 2 or more may be the same or different. The method of Claim 1 which is a compound shown by these. 3. An acyl ester of phenols has the formula Y _n -C ₆ H _5-n -OCO-R (III) (wherein Y is a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkoxy group). A halogen atom, a cyano group or a nitro group,
n is an integer of 0 to 5, and when n is 2 or more, Ys of 2 or more may be the same or different, and R is C ₁ to C.
_{3 is} an alkyl group. The method of Claim 1 which is a compound shown by these. 4. Carbonates having at least one alkyl group have the formula R ¹ —OCOO—R ² (IV) (wherein R ¹ and R ² are C ₁ -C ₆ alkyl groups, and are the same). Or may be different), the method according to claim 1, which is a dialkyl carbonate. 5. Carbonates having at least one alkyl group have the formula Ar—OCOO—R ³ (V) (wherein R ³ is a C ₁ -C ₆ alkyl group and Ar is of the formula Y _n -C ₆ H _5-n - is a group represented by, Y is C ₁ -C ₆ alkyl group, C ₁
To C ₆ alkoxy group, halogen atom, cyano group or nitro group, n is an integer of 0 to 5, and when n is 2 or more, 2 or more Ys may be the same or different. The method according to claim 1, which is a monoalkyl monoaryl carbonate ester represented by the formula (1).