KR100501834B1 - Method for preparing Diphenyl Carbonate - Google Patents

Abstract

The present invention relates to a method for preparing diphenyl carbonate, and more particularly, in the process for preparing diphenyl carbonate by reacting dimethyl carbonate and phenol in the presence of a catalyst, the reaction catalyst is represented by the following formula (1) By using a mixture of organotin oxide and sulfuric acid derivative represented by Formula 2 at the same time at a certain ratio, it is possible to produce diphenyl carbonate in a wider temperature range and in a higher yield in a short time than conventional methods of using a conventional catalyst, The present invention relates to a process for preparing diphenyl carbonate to minimize the production of reactants.

R ₂ SnO

R ¹ SO ₃ H

Description

Method for preparing diphenyl carbonate {Method for preparing Diphenyl Carbonate}

The present invention relates to a method for preparing diphenyl carbonate, and more particularly, in the process for preparing diphenyl carbonate by reacting dimethyl carbonate and phenol in the presence of a catalyst, the reaction catalyst is represented by the following formula (1) By using a mixture of organotin oxide and sulfuric acid derivative represented by the formula (2) at the same time at a certain ratio, diphenyl carbonate can be drawn at a high yield in a wider temperature range and within a short time as compared to the conventional method of using a conventional catalyst, as well as conventional side reactions It relates to a method for producing diphenyl carbonate to minimize the production of.

[Formula 1]

R ₂ SnO

Wherein R is an alkyl group or phenyl (C ₆ H ₅ -) of the C ₁ ~C ₆ is a group.

[Formula 2]

R ¹ SO ₃ H

R ¹ is a halogen atom, a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ haloalkyl group or a tolyl group (CH ₃ C ₆ H ₅ −).

Polycarbonates are used in many applications because of their excellent mechanical properties such as impact resistance, good heat resistance and transparency. The polycarbonate has been prepared by interfacial polymerization of phosgene and bisphenol-A, but due to the toxic toxicity of phosgene, the generation of by-products such as HCl, the use of excess methylene chloride in the interfacial polymerization, and the large amount of wastewater generated in the washing process. Increasingly, a method of using diphenyl carbonate as a raw material instead of phosgene has been developed.

In general, diphenyl carbonate can be prepared in a two-step equilibrium reaction of methyl carbonate by reacting dimethyl carbonate (DMC) with phenol, as shown in Scheme 1 below, but the equilibrium is biased to the reactant and the reaction rate is slow. Therefore, various catalyst systems have been proposed to improve the yield of diphenyl carbonate.

Examples of a method for producing diphenyl carbonate using the various catalyst systems include a method using titanium oxide having a high surface area as a catalyst [US Pat. No. 5,354,923] and titanium supported on activated carbon, respectively. 231471] or a method using molybdenum supported on silica as a catalyst (Japanese Patent Laid-Open No. 8-231472). All of the catalysts are heterogeneous and have an advantage in that the reactants and the catalysts are easily separated after the reaction, but the yield of diphenyl carbonate as a product is 1 to 3% when the reaction is carried out at a temperature of 160 to 200 ° C. for 3 to 5 hours. There is a problem as low as that.

In addition, there is a method for producing diphenyl carbonate in a yield of about 50% at a temperature of 190 ℃ by disproportionation of methylphenyl carbonate in the presence of a PbO ₂ catalyst (US Pat. No. 5,166,393). However, there is a disadvantage in that the economic efficiency of the methylphenyl carbonate is expensive and the manufacturing method is not suitable.

As another method of using a catalyst, a catalyst such as Fe (OPh) ₃ or Ti (OPh) ₄ is used for the transesterification reaction of dimethyl carbonate and phenol, respectively [JP-A-7-033714, U.S. Patent 4,182,726]. There is also a method of making, but not only mentions the production of methylphenyl carbonate, which is a precursor of diphenyl carbonate, but also a low yield of about 10 to 30%.

In addition, there is a method for preparing diphenyl carbonate from dimethyl carbonate using various organotitanium and organotin (US Patent No. 4,410,464). The above manufacturing method proposes a method of preparing methylphenyl carbonate first through a transesterification reaction and then separating it, and then preparing a diphenyl carbonate through disproportionation reaction. have.

When the production method of diphenyl carbonate is carried out in the presence of a general catalyst, there is a problem in that the yield of the product is low and by-products from side reactions are generated. In order to solve this problem, an organic tin oxide and a sulfate derivative are mixed together as a reaction catalyst. The present invention was completed by developing a new method for producing diphenyl carbonate, which greatly improves the reaction rate, completes the reaction in a short time, and suppresses side reactions as much as possible, thereby greatly improving the yield of the target product.

The present invention provides a method for producing diphenyl carbonate in the presence of a catalyst of dimethyl carbonate and phenol, wherein the reaction catalyst is a mixture of the organic tin oxide represented by the following formula (1) and the sulfuric acid derivative represented by the formula (2) It features.

[Formula 1]

R ₂ SnO

Wherein R is an alkyl group or phenyl (C ₆ H ₅ -) of the C ₁ ~C ₆ is a group.

[Formula 2]

R ¹ SO ₃ H

R ¹ is a halogen atom, a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ haloalkyl group or a tolyl group (CH ₃ C ₆ H ₅ −).

 The present invention will be described in detail as follows.

The present invention is characterized by reacting dimethyl carbonate and phenol in the presence of a mixed catalyst of organic tin oxide and sulfuric acid derivative, and greatly improves the production rate of diphenyl carbonate in a wide temperature range within a short time than the conventional method using a catalyst The present invention relates to a method for preparing economically useful diphenyl carbonate by suppressing side reactions.

The catalyst used in the reaction for preparing diphenyl carbonate in the present invention is a mixture of an organotin oxide (Chemical Formula 1) and a sulfuric acid derivative (Chemical Formula 2) together, the catalyst is in the range of 0.1 to 10 mol% relative to the reactant dimethyl carbonate Use within. If the amount is less than 0.1 mol%, the reaction rate is too slow, and if it exceeds 10 mol%, there is a problem that the reaction rate and selectivity are not improved beyond the limit line. Specific examples of the organic tin oxide represented by Chemical Formula 1 include (CH ₃ ) ₂ SnO, (C ₂ H ₅ ) ₂ SnO, (C ₃ H ₇ ) ₂ SnO, (C ₅ H ₁₂ ) ₂ SnO, (C ₆ H ₁₄ ) One or more selected from ₂ SnO and Ph ₂ SnO may be used. Specific examples of the sulfuric acid derivative represented by Formula 2 include CH ₃ PhSO ₃ H, CF ₃ SO ₃ H, FSO ₃ H, and ClSO ₃ One or more selected from H, CH ₃ SO ₃ H, and CF ₃ SO ₃ H may be used.

The role of the catalyst used in the present invention is to make the reaction easy by lowering the activation energy of the reaction. That is, during the reaction, the sulfuric acid derivative first reacts with the organotin compound to reduce the electron density of tin, thereby making tin have a stronger Lewis acidic property, and the reactants phenol and dimethyl carbonate are easier to catalyze. To be coordinated. As a result, the reaction occurs more easily, thereby increasing the yield of the desired product and suppressing the formation of side reactions. The sulfuric acid derivative in the catalyst is mixed and used in an amount of 0.2 to 5 molar ratios of the organic tin oxide, and preferably the same amount molar ratio. The two catalysts react with each other to form a new type of catalyst. If the two catalysts are out of the mixing range, the synergistic effect of the two catalysts does not appear.

In the present invention, phenol used as a reactant together with dimethyl carbonate is used in the range of 2 to 20 moles of dimethyl carbonate. As shown in Scheme 1, since two molecules of phenol react with one molecule of dimethyl carbonate to produce diphenyl carbonate, the amount of phenol should be at least 2 molar ratio based on the amount of dimethyl carbonate. However, if the amount of use increases in the range of 2 to 20 molar ratio, but exceeds 20 molar ratio, the amount of diphenyl carbonate produced is almost constant regardless of the amount of reactants.

The present invention performs the reaction shown in Scheme 1 using an organotin oxide and a sulfate derivative composed of a certain ratio as a catalyst to the reaction product of dimethyl carbonate and phenol. The said reaction temperature is 130-250 degreeC, and reaction time is 1 to 24 hours. If the reaction temperature is less than 130 ℃ reaction rate is slow, at a high temperature of more than 250 ℃ dimethyl carbonate, which is a reactant, or the production of by-products in addition to the target product increases the problem that the selectivity worsens.

The reaction can also be carried out using a batch or continuous reactor. When the reactor is a batch, methanol generated during the reaction may be removed by passing through a molecular sieve layer filled on the reactor.

The present invention was carried out by using a certain ratio of the organic tin oxide and sulfuric acid derivative as a catalyst to react dimethyl carbonate and phenol under the specific conditions as described above. As a result, the yield of diphenyl carbonate was improved and side reactions were reduced.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are not intended to limit the present invention.

Example 1

In a 100 ml high pressure reactor, dimethyl carbonate (3.6 g, 40 mmol) and phenol (18.8 g, 200 mmol) were dissolved in benzene (40 ml), followed by dibutyltin oxide (0.099 g, 0.4 mmol) and methanesulfonic acid ( 0.038 g, 0.4 mmol) is added. The cylinder mounted above the reactor is filled with 30 g of molecular sieve 4A, and the reactor is connected to a vacuum pump to remove air inside the reactor. The temperature of the reactor was raised to 180 ° C. at a rate of 10 ° C./min and reacted for 3 hours. After the reaction, the mixture was analyzed using gas chromatography. As a result, a yield of 35% methylphenyl carbonate and 20.1% diphenyl carbonate was produced.

The yield of each product of the present invention was calculated by the same method as in Equation 1.

Example 2

It was carried out under the same conditions as in Example 1, but was performed by adding different types of organotin oxide and sulfuric acid derivative, which is the catalyst. The prepared mixture was analyzed by gas chromatography and shown in Table 1 below.

Organotin oxide Sulfuric acid derivative Yield of methylphenyl carbonate (%) Yield of diphenyl carbonate (%) (CH ₃ ) ₂ SnO CH ₃ PhSO ₃ H 38.7 20.9 (C ₂ H ₅ ) ₂ SnO CF ₃ SO ₃ H 39.8 19.8 (C ₃ H ₇ ) ₂ SnO FSO ₃ H 33.5 18.5 (C ₅ H ₁₂ ) ₂ SnO ClSO ₃ H 33.2 15.4 (C ₆ H ₁₄ ) ₂ SnO CH ₃ SO ₃ H 31.5 17.8 Ph ₂ SnO CF ₃ SO ₃ H 34.2 18.4

Example 3

The same conditions as in Example 1 were carried out, except that the amount of dibutyltin oxide, the organic tin oxide, in the organotin oxide and the sulfate derivative was fixed and the amount of methanesulfonic acid in the sulfate derivative was changed and added. The prepared mixture was analyzed by gas chromatography and shown in Table 2 below.

Amount of methanesulfonic acid (molar ratio) Yield of methylphenyl carbonate (%) Yield of diphenyl carbonate (%) 0.2 20.1 5.2 0.5 25.6 15.4 1.5 30.1 16.2 2 22.1 8.7 5 13.2 1.8

Example 4

It was carried out under the same conditions as in Example 1, except that difluorotintin oxide and sulfuric acid derivatives trifluoromethanesulfonic acid were added as organotin oxide as the catalyst, and the amount of the catalyst was changed. The prepared mixture was analyzed by gas chromatography and shown in Table 3 below.

Diphenyltin oxide amount (mol%) Trifluoromethanesulfonic acid amount (mol%) Methylphenylcarbonate yield (%) Diphenylcarbonate yield (%) 0.1 0.1 15.5 3.5 0.2 0.2 21.8 8.4 0.5 0.5 33.2 13.9 One One 38.5 20.2 2 2 45.6 25.9 5 5 46.2 27.8 10 10 43.1 29.5

Example 5

The reaction was carried out under the same conditions as in Example 1 except that dibutyl tin oxide and toluene sulfonic acid were added as the catalyst to change the reaction temperature. The prepared mixture was analyzed by gas chromatography and shown in Table 4 below.

Reaction temperature (℃) Yield of methylphenyl carbonate (%) Yield of diphenyl carbonate (%) 130 8.5 _ 150 20.4 6.8 200 39.2 25.9 220 38.5 42.6 250 21.5 56.3

Example 6

Using the same conditions as in Example 1, it was carried out while changing the molar ratio ([phenol] / [dimethyl carbonate]) of phenol to dimethyl carbonate by adding diphenyltin oxide and fluorosulfonic acid as the catalyst. The prepared mixture was analyzed by gas chromatography and shown in Table 5 below.

Molar ratio of [phenol] / [dimethyl carbonate] Yield of methylphenyl carbonate (%) Yield of diphenyl carbonate (%) 2 34.1 13.5 5 38.6 19.8 10 40.5 21.2 15 39.8 23.1 20 38.9 24.8

Comparative Example 1

It was carried out under the same conditions as in Example 1, the catalyst was carried out by the addition of dibutyl tin oxide (0.099 g, 0.4 mmol). The prepared mixture is shown in Table 6 by gas chromatography.

Comparative Example 2

The same process as in Example 1 was carried out, but the catalyst was performed by adding methanesulfonic acid (0.038 g, 0.4 mmol). The prepared mixture was analyzed by gas chromatography and shown in Table 6 below.

Comparative Example 3

It was carried out under the same conditions as in Example 1 except that titanium isopropoxide (0.113 g, 0.4 mmol) was added as a catalyst. The prepared mixture was analyzed by gas chromatography and shown in Table 6 below.

division catalyst Yield of methylphenyl carbonate (%) Yield of diphenyl carbonate (%) Yield of Anisole (%) Yield of methyl isopropyl carbonate (%) Yield of diisopropyl carbonate (%) Comparative Example 1 Bu ₂ SnO 16.7 4.6 0.4 - - Comparative Example 2 CH ₃ SO ₃ H 9.8 _ 1.5 - - Comparative Example 3 Ti [OCH (CH ₃ ) ₂ ] ₄ 33.1 15.3 - 1.0 0.3

As can be seen from Examples 1 to 6 and Comparative Examples 1 to 3, the yield of diphenyl carbonate was improved by at least 14 times as compared with the comparative example, and the yield of methyl carbonate, which is a reaction intermediate, was also improved.

In addition, the reaction activity was higher than that of Example 1, which was used by mixing an organotin oxide, and a sulfate derivative, respectively, and Comparative Example 2 and Comparative Example 3, each of which was used alone. In addition, Comparative Example 3 using the titanium isopropoxide, which is an existing catalyst, not only lowered the yield of diphenyl carbonate, but also produced 1.0% methyl isopropyl carbonate and 0.3% diisopropyl carbonate as by-products.

Example 2 shows a change in the yield of the product according to the type of catalyst, Example 3 is a change in the yield of the product according to the amount of sulfuric acid derivative in the catalyst, Example 4 is a change in the amount of catalyst for the reactant dimethyl carbonate Yield change of the product according to the present invention, Example 5 shows the yield change of the product according to the reaction temperature, Example 6 shows the yield change of the product according to the change amount of the phenol according to the dimethyl carbonate Showed the effect.

As described above, according to the production method according to the present invention it is possible to effectively prepare diphenyl carbonate which is a raw material of the industrially useful polycarbonate in a high yield without a side reaction in a short time in a wider temperature range than the conventional method.

Claims (6)

In the method for producing diphenyl carbonate in the presence of a catalyst of dimethyl carbonate and phenol, the reaction catalyst is characterized in that the organic tin oxide represented by the following formula (1) and the sulfuric acid derivative represented by the formula (2) is used together Process for preparing phenyl carbonate: [Formula 1] R ₂ SnO R is a C ₁ -C ₆ alkyl group or a phenyl (C ₆ H _5- ) group; [Formula 2] R ¹ SO ₃ H R ¹ is a halogen atom, a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ haloalkyl group or a tolyl group (CH ₃ C ₆ H ₅ −). The method according to claim 1, wherein the catalyst is used in an amount of 0.1 to 10 mol% based on dimethyl carbonate. The method for producing diphenyl carbonate according to claim 1, wherein the molar ratio ([sulfurate derivative] / [organic tin oxide]) of the sulfuric acid derivative and the organic tin oxide is 0.2 to 5. The method for producing diphenyl carbonate according to claim 1, wherein the molar ratio ([phenol] / [dimethyl carbonate]) of the phenol and dimethyl carbonate is 2 to 20. The method for producing diphenyl carbonate according to claim 1, wherein the reaction temperature is 130 to 250 ° C and the reaction time is 1 to 24 hours. The method of claim 1, wherein the reaction is a batch or continuous reactor using a method for producing diphenyl carbonate.