JPS6143338B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a carbonic ester by reacting an aliphatic alcohol with carbon monoxide and oxygen in a gas flow system in the presence of a catalyst. Carbonate ester is an industrially useful substance as an intermediate for polycarbonate production, and is produced by reacting alcohol with phosgene, but phosgene is highly toxic and the electrolytic chlorine required to produce phosgene is expensive. Also, highly corrosive hydrochloric acid is produced as a by-product due to the reaction of alcohol and phosgene, and so there is a desire to develop an industrial method for producing carbonate esters that does not use phosgene. In order to meet these demands, a method has been proposed in which alcohol is reacted with carbon monoxide and oxygen in the presence of a copper salt catalyst or selenium catalyst to produce carbonate esters, but in the method using a copper salt catalyst, However, there are still problems such as large combustion loss of carbon monoxide, and methods using selenium catalysts have no established method for recovering toxic selenium catalysts, and the reaction rate is low. . The present inventors have searched for catalysts for the reaction of producing carbonic acid esters from alcohol, oxygen and carbon monoxide, and have found that platinum group metals or their salts,
The partial pressure of carbon monoxide is reduced to 1 using at least one three-component catalyst selected from the group consisting of alcohol-soluble copper salts and trialkylamines, heterobridged cyclic tertiary amines, alkali metal salts, and alkali metal alkoxides. Oxidative carbonylation of aliphatic alcohols by flowing carbon monoxide and oxygen through the reaction system at ~15 Kg/cm ² produces carbonate esters at a high reaction rate and with good selectivity, and is suitable for batch reactions. It has been found that comparatively very low carbon monoxide partial pressures and oxygen partial pressures can be adopted,
This has led to the present invention. On the other hand, as a reaction closely related to the reaction in the method of the present invention, a reaction with a relatively high carbon monoxide content is performed in the presence of a catalyst consisting of a platinum group metal salt, copper salt, or iron salt and various basic organic or inorganic compounds. A reaction to obtain oxalate ester from alcohol, oxygen and carbon monoxide under pressure is known. (Japanese Patent Publication No. 50-131917, Japanese Patent Application Publication No. 51-6916, etc.). In the reaction to obtain the oxalic acid ester mentioned above, in addition to the main product oxalic acid ester, small amounts of carbonic acid ester and formic acid ester are produced as by-products, but all of these data are based on a carbon monoxide partial pressure of 40 to 100 Kg/cm. ²
The reaction was carried out in however,
Through detailed study by the inventors, the partial pressure of carbon monoxide
At around 30Kg/ ^cm2 , the amount of oxalate ester and carbonate ester produced is almost balanced, and when the partial pressure of carbon monoxide is ^below 15Kg/cm2, carbonate ester is obtained as the main product, and the amount of oxalate ester produced is only a trace. It has also been found that sufficient reaction rates can be obtained under appropriate oxygen partial pressures even when the reaction is carried out under conditions of low carbon monoxide partial pressure. The present invention will be explained in detail below. In the present invention, the carbon monoxide partial pressure is 1 to 15 kg/
In a gas flow system that continuously supplies carbon monoxide and oxygen to the reaction system and continuously exhausts the gas in the reaction system under conditions of ² cm2, aliphatic alcohol is mixed with platinum group metal or its salt, By reacting with oxygen and carbon monoxide in the presence of at least one selected from the group consisting of alcohol-soluble copper salts and trialkylamines, heterobridged cyclic tertiary amines, alkali metal salts and alkali metal alkoxides. A carbonate ester is produced. As the aliphatic alcohol, saturated aliphatic alcohols, particularly lower aliphatic saturated alcohols such as methanol, ethanol, and butanol, are preferably used, and are usually used in excess to serve as a solvent. Examples of platinum group metals include ruthenium, rhodium,
Palladium, iridium, platinum, etc. are used, and palladium is particularly preferred. These metals can be used alone or as salts such as halides, nitrates, sulfates, phosphates, and acetates, and can also be used as activated carbon, graphite,
Alumina, silica, silica-alumina, diatomaceous earth,
Asbestos, ion exchange resin, calcium silicate,
It can also be used by being supported on a carrier such as aluminosilicate. The amount of platinum group metal or its salt used is usually 0.001 to 10 per liter of aliphatic alcohol.
It is selected as appropriate within the range of g. Examples of alcohol-soluble copper salts include halides such as cupric chloride and cuprous chloride, as well as nitrates, sulfates, acetates, and phosphates.
These copper salts are used in an amount of 1 to 1000 times the weight of the platinum group metal or its salt. As the trialkylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, etc. are used, and as the heterobridged cyclic tertiary amine, 1,5-diazabicyclo[4.3.0]nonene-5,1,8-diazabicyclo[ In addition to bicyclic amidines such as 5.4.0] undecene-7, 1,8-diazabicyclo[2.2.2]octane and the like are used. Examples of alkali metal salts include aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, and caproic acid, alkali metal salts such as lithium, sodium, and potassium of inorganic acids such as carbonic acid, nitric acid, sulfuric acid, and phosphoric acid, or potassium chloride. , lithium chloride, cesium chloride, and other alkali metal halides are used;
As the alkali metal alkoxide, sodium methoxide, sodium ethoxide, potassium methoxide, etc. are used. The amount used is 0.5 to 100 times the weight of the platinum group metal or its salt. In the method of the present invention, tetramethylammonium chloride, tetra-n-butylammonium chloride, tetra-n-butylammonium iodide, tri-n-octyl mono- n-propylammonium, tetra-n-octylammonium iodide,
A quaternary ammonium salt such as tetra-n-butylammonium bromide may be used in an amount of 0.5 to 100 times the weight of the platinum group metal or its salt. In the method of the present invention, as mentioned earlier,
Usually, an excess amount of aliphatic alcohol is used also as a solvent, but a solvent inert to the reaction can also be used. Specifically, benzene, toluene,
Aromatic hydrocarbons such as xylene, chlorobenzene,
Dichlorobenzene, halogenated aromatic hydrocarbons such as trichlorobenzene, aliphatic saturated hydrocarbons such as octane and decane, 1,1,2-trichloro-1,
Examples include halogenated aliphatic hydrocarbons such as 2,2-trifluoroethane, and ethers such as tetrahydrofuran and 1,4-dioxane. The method of the invention is carried out in a gas flow system or a gas-liquid flow system. That is, a gas flow reaction in which an aliphatic alcohol and a catalyst are charged into a reactor, carbon monoxide and oxygen are continuously supplied, and reaction waste gas containing carbon dioxide produced by a side reaction is discharged from the reactor. Alternatively, it can be carried out by a conventional continuous reaction in which the aliphatic alcohol or a liquid phase containing the aliphatic alcohol and the catalyst is also continuously fed into the reactor, and the reaction product liquid is continuously discharged from the reactor together with the reaction waste gas. . Carbon monoxide and oxygen are used in equimolar to 1000 times the amount consumed in the reactor, preferably 2 to 500 times the amount consumed in the reactor, and the partial pressure of carbon monoxide in the reactor is 1 to 15 kg/mole.
cm ² , preferably within the range of 1 to 10 Kg/cm ² , and the oxygen partial pressure is adjusted to be within the range of 0.1 to 10 Kg/cm ² , preferably 0.1 to 5 Kg/cm ² . Carbon monoxide and oxygen can be used in their pure forms, but they can also be used diluted with a gas inert to the reaction, such as nitrogen or argon. In particular, it is desirable to adjust the oxygen partial pressure so that the gas composition within the reaction system is out of the explosive range. The reaction of the present invention is carried out at 30-200°C, preferably at 60-150°C.
It is carried out for 1 to 10 hours within the temperature range of °C. After the reaction product liquid is cooled by a conventional method, the catalyst and the like can be separated and recovered, and the carbonate ester can be purified and obtained by operations such as distillation and extraction. As explained above, if the present invention is carried out by a gas flow reaction or a continuous reaction, the optimum conditions for carbon monoxide partial pressure and oxygen partial pressure with respect to the selectivity of carbonate ester will be on the lower pressure side than in the case of a batch reaction. It is industrially very advantageous because of the deviation. Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless the essential points are exceeded. Examples 1 to 6 Internal volume with a stirrer with a condenser installed at the gas outlet
In a 200ml titanium autoclave, 2g of activated carbon with a palladium loading of 2% by weight (hereinafter referred to as 2%Pd/C), 10.0mmole of cupric acetate, and potassium chloride.
20.0mmole, tetrabutylammonium iodide
4.0 mmole and 90 ml of methanol were charged, and the inside of the autoclave was purged with nitrogen. Next, carbon monoxide and nitrogen containing 6 mole% oxygen are shown in Table-1.
After pressurizing the nitrogen to the partial pressure listed in Table 1, the flow rate of nitrogen containing carbon monoxide and 6 mole% oxygen was set to the values listed in Table 1, and the nitrogen was supplied to the autoclave and exhausted through the condenser. Gas distribution system. Rotate the stirrer at 500 r/p/m to heat the autoclave to 80°C while stirring it, react for 3 hours, cool to room temperature, release the pressure, and analyze the reaction product liquid by gas chromatography. Dimethyl carbonate and dimethyl oxalate were determined. The results are shown in Table-2.

【table】

[Table] Example 7 A reaction was carried out in the same manner as in Example 5 under the same reaction conditions except that tetrabutylammonium iodide was not used. As a result, the amount of dimethyl carbonate produced was 42.3 mmole
Therefore, dimethyl oxalate was not produced. Examples 8 to 12 The reaction was carried out in the same manner as in Example 1, except that 0.4 mmole of palladium or palladium salt listed in Table 3 was used instead of 2% Pd/C. The results are shown in Table-3.

[Table] Examples 13-14 Table instead of cupric acetate and potassium chloride -
The reaction was carried out in the same manner as in Example 1, except that the promoter shown in Example 4 was used. The results are shown in Table-4.

【table】

[Table] Example 15 2% Pd/C2g, cupric chloride 10.0mmole, 1,
8-Diazabicyclo [5.4.0] Undecene-
720.0mmole, tetrabutylammonium iodide
4.0 mmole and 90 ml of methanol were charged into an autoclave, and the reaction was carried out under the same reaction conditions as in Example 5. As a result, the amount of dimethyl carbonate produced was 44.1 mmole
and traces of dimethyl oxalate were present. Example 16 Reaction conditions were set such that the partial pressure of carbon monoxide was 7.1 Kg/cm ² , the partial pressure of nitrogen containing 6 mole% oxygen was 40.9 Kg/cm ² , and the respective flow rates were 8.0 Nl/hr and 46.0 Nl/hr. The reaction was carried out in the same manner as in Example 15 except for the following changes. As a result, the amount of dimethyl carbonate produced was 23.0 mmole
The amount of dimethyl oxalate produced was 63.5 mmole.

Claims (1)

[Scope of Claims] 1. At least one member selected from the group consisting of platinum group metals or their salts, alcohol-soluble copper salts, and trialkylamines, heterobridged cyclic tertiary amines, alkali metal salts, and alkali metal alkoxides. In this method, carbon monoxide and oxygen are continuously added to the reaction system under a carbon monoxide partial pressure of 1 to 15 Kg/ ^cm2 . A method for producing a carbonic ester, characterized by supplying the carbonic acid ester and continuously discharging the gas in the reaction system. 2. In the method described in claim 1,
A method for producing a carbonate ester, which comprises continuously supplying an aliphatic alcohol to a reaction system and continuously discharging a reaction product liquid from the reaction system. 3. A method for producing a carbonate ester according to claim 1 or 2, which comprises reacting an aliphatic alcohol with carbon monoxide and oxygen in the coexistence of a quaternary ammonium salt.