JP3531298B2 - Catalyst for diaryl carbonate production - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst used for producing diaryl carbonate, which is a raw material of polycarbonate as a raw material resin for containers and optical disk substrates. [0002] It is known to produce diaryl carbonates by reacting an aromatic hydroxy compound with a carbonyl halide such as phosgene in the presence of a catalyst. For example, US Pat. No. 2,837,555 proposes performing solventless condensation in the presence of a tetramethylammonium halide as a catalyst. However, this method requires a relatively large amount of catalyst in order to obtain an economical reaction rate, and requires a large amount of catalyst.
It is necessary to carry out the reaction at a relatively high temperature of 0 to 215 ° C., with the risk of decomposition of the thermally unstable tetramethylammonium halide. In addition, phosgene is consumed at a much higher rate than is required stoichiometrically. JP-B-58-50977 proposes a method for producing a diaryl carbonate by reacting phenol with phosgene in the presence of a nitrogen-containing heterocyclic base such as pyridine or quinoline using phenol as a catalyst. This method is simpler than the above-mentioned method and gives a better yield, but further improvement in the yield is desired. Further, JP-A-7-53473 and JP-A-7-53474 disclose a process for producing aryl carbonates by reacting an aromatic monohydroxy compound with phosgene or a chloroformate of an aromatic monohydroxy compound. The reaction is carried out in the presence of one or more aluminum oxides or aluminosilicates as heterogeneous catalyst under a pressure of 0.2 to 20 bar.
A method is proposed, characterized in that it is carried out at a temperature in the range from 0 to 350 ° C. However, in this method, the conversion of the aromatic hydroxy compound (phenol) is at the maximum of 20%, and does not necessarily show a satisfactory catalytic activity as an industrial catalyst. SUMMARY OF THE INVENTION The present invention is to provide a catalyst for producing a diaryl carbonate which has an industrially satisfactory high activity and selectivity. SUMMARY OF THE INVENTION The present invention is directed to a catalyst used for producing a diaryl carbonate by reacting an aromatic hydroxy compound with a carbonyl halide in a liquid phase, wherein the catalyst is hydroxy. It is intended to provide a catalyst for producing a diaryl carbonate, which is a pyridine-based compound containing a group or an alkoxyl group. This catalyst exhibits a specifically high catalytic activity, has good selectivity, and provides the desired diaryl carbonate in high yield. (Summary of the Invention) The aromatic hydroxy compound used as the starting material for the aromatic hydroxy compound is represented by the formula (1) Ar-OH (1) wherein Ar is phenyl, naphthyl, anthryl, Represents phenanthryl, indanyl or tetrahydronaphthyl or a group derived from a 5- or 6-membered aromatic heterocyclic compound having one or two heteroatoms from the groups N, O and S, wherein Is substituted with one or two substituents, for example, a linear or branched C ₁ -C ₄ alkyl group, a linear or branched C ₁ -C ₄ alkoxy group. Which may be substituted with phenyl, cyano, and halogen (eg, F, Cl, Br), and further wherein these heterocyclic groups are linked to a fused benzene ring. It may be tied. ] It is a compound represented by these. Specifically, phenol, o-, m- and p-cresol, o-, m- and p-isopropylphenol, and corresponding halogen or alkoxyphenols such as p-chlorophenol or p-methoxyphenol And also monophthalic compounds of naphthalene and anthracene. Among them, phenol is most suitable. Halogenated carbonyls Examples of carbonyl halides include phosgene and bromocarbonyl, and phosgene is generally used. Catalyst The catalyst used in the present invention is 2-hydroxypyridine,
-Methoxypyridine. These are used alone or in combination. The catalyst of the present invention is used in an amount of 0.1 to 20 mol%, preferably 0.5 to
It is used in an amount of 10 to 10 mol%, more preferably 1 to 5 mol%. Production of diaryl carbonate Diaryl carbonate is prepared by reacting an aromatic hydroxy compound and a carbonyl halide with the above catalyst at 100 to 2
It is carried out in the liquid phase at a temperature of 50C, preferably 100-180C, more preferably 130-180C. It is preferably carried out in the molten state of the raw materials, in which case the reaction is carried out at a reaction temperature equal to or higher than the melting points of the aromatic hydroxy compound and the diaryl carbonate. By adopting such a temperature condition, the production of allyl chloroformate is suppressed, and the desired diaryl carbonate can be efficiently produced. If necessary, the reaction may be carried out using a solvent, such as an aliphatic or aromatic hydrocarbon such as pentane, hexane, octane, benzene, or the like.
Isomeric xylenes, diethylbenzene, alkylnaphthalenes, biphenyl, halogenated hydrocarbons such as dichloromethane, trichloroethylene and the like can be mentioned. The mode of reaction is to pass a carbonyl halide through a solution of the catalyst in the aromatic hydroxy compound to optionally, continuously or discontinuously remove the hydrogen halide formed during the reaction. Perform the reaction while After the reaction is completed, the product and the catalyst are separated by, for example, distillation. These reactants are reacted at a molar ratio of aromatic hydroxy compound to carbonyl halide of 0.5 to 8: 1, preferably 1.5 to 3: 1. The equimolar ratio in this case is 2: 1. According to the method for producing a diaryl carbonate using the catalyst of the present invention, the resulting crude diaryl carbonate can be obtained in a very high purity, so that the crude diaryl carbonate is obtained by degassing residual hydrogen halide or other volatile substances. Although possible, further purification of the diaryl carbonate may optionally be performed, eg, by distillation or crystallization, depending on the application. The present invention will be specifically described below with reference to examples. Example 1 In a 100 ml glass corbane equipped with a stirrer and a reflux condenser, 47 g (0.5 mol) of phenol and 3 mol% of 2-hydroxypyridine with respect to phenol were charged, and N ₂ flow rate was measured. And heated to 150 ° C. When the temperature reached 150 ° C., 0.6 g of phosgene /
At a flow rate of 1 min into the glass kolben and continuously bubbled for 45 min. Phosgene was supplied to the reaction system in a total amount of 0.275 mol. After the bubbling, the conversion of phenol was 62.0%, and the yield of diphenyl carbonate was 61.9%. Further, the yield of phenylchloroformate was 0.5%. Example 2 Instead of the 2-hydroxypyridine used in Example 1, 2
The same reaction as in Example 1 was performed using -methoxypyridine. Table 1 shows the results. Example 3 In Example 1, the reaction temperature was increased to 170 ° C.
The reaction was performed for 5 minutes. The results are shown in FIG. Comparative Examples 1-2 The reaction was carried out in the same manner as in Example 1 except that pyridine or quinoline was used as a catalyst instead of 2-hydroxypyridine used in Example 1. Table 1 shows the results. [Table 1] Example 4 The same experiment as in Example 3 was performed. That is, 47 g (0.5 mol) of phenol, 3 mol% based on phenol
Phosgene was supplied at a temperature of 170 ° C. at a feed rate of 0.6 g / min. However,
The composition of the reaction solution was analyzed over time using a gas inlet tube equipped with a G-2 glass filter in order to improve the gas-liquid contact efficiency. The result is shown in FIG. As is apparent from FIG. 1, diphenyl carbonate (DPC) is generated from the beginning of the reaction.
The formation of phenylchloroformate (PCF) was hardly observed. When the reaction between the aromatic hydroxy compound and the carbonyl halide is carried out using the catalyst of the present invention, it is recognized that the reaction is not a curved sequential reaction from the change in the composition of the product over time. That is, the generation of the aromatic chloroformate, which is expected to be an intermediate product, is extremely small from the beginning of the reaction, and the diaryl carbonate is obtained substantially without passing through the aromatic chloroformate. According to the present invention, a diaryl carbonate can be efficiently produced from an aromatic hydroxy compound and a carbonyl halide by using the catalyst of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows the results when phosgene was supplied to a reaction system at a rate of 0.6 g / min using 2-hydroxypyridine as a catalyst.
It is a correlation diagram which shows the phosgene supply time and the ratio of mol% of each component in a reaction system. [Description of Signs] PhOH Phenol PCF Phenyl Chloroformate DPC Diphenyl Carbonate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-63148 (JP, A) JP-A-51-110535 (JP, A) JP-A-54-109940 (JP, A) 255199 (JP, A) JP-A-8-143584 (JP, A) JP-A-6-128215 (JP, A) JP-B-42-1372 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 B01D 53/86 C07B 61/00

Claims (1)

(57) Claims 1. A catalyst used for producing a diaryl carbonate by reacting an aromatic hydroxy compound with a carbonyl halide in a liquid phase, wherein the catalyst is 2-hydroxy A catalyst for producing diaryl carbonate, which is a pyridine compound selected from pyridine and 2-methoxypyridine.