JPS628113B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing carbonic acid diesters by a novel reaction. Carbonic diester is used as a solvent and
It is also a useful compound as a raw material for producing polycarbonate. Conventionally, a method of reacting alcohol and phosgene has been known as a method for producing carbonic diester.
However, this method uses highly toxic phosgene that is inconvenient to handle, requires expensive electrolytic chlorine to prepare phosgene, and produces highly corrosive hydrochloric acid as a by-product from the reaction between alcohol and phosgene. It has many drawbacks such as: Furthermore, in recent years, various proposals have been made regarding the production method of carbonic acid diester by reacting alcohol, carbon monoxide, and oxygen. However, these methods
All of the catalyst systems used are complex and consist of several components, and therefore have a common drawback in that their separation, recovery and regeneration require complicated operations. The present inventors conducted extensive research with the aim of developing an industrially superior manufacturing method for carbonic diester. As a result, if a nitrite ester and carbon monoxide are subjected to a liquid phase reaction in the presence of a platinum group metal or its salts at a carbon monoxide partial pressure of 0.1 to 3 Kg/cm ² and a temperature of 20 to 150°C, The inventors have discovered that carbonic acid diesters can be produced very industrially and advantageously, and have arrived at the present invention. The present invention provides a method for producing carbonic acid diester by a novel reaction, and since only a platinum group metal catalyst is used as a catalyst, its separation, recovery and regeneration are extremely simple compared to conventional methods. In the present invention, although the mechanism of the reaction that occurs on the catalyst has not yet been fully elucidated, the main reaction seems to be the reaction shown in the following formula. (However, in the formula, R represents an alkyl group, a cycloalkyl group, or an aryl group.) The nitrite esters used in the method of the present invention include saturated monovalent or divalent aliphatic alcohols, alicyclic alcohols, and aralkyl alcohols. It is an ester of nitrous acid and an alcohol having 1 to 20 carbon atoms consisting of the group consisting of, for example, methanol, ethanol, n- and iso-propanol, n-, iso-, sec-, tert
- Aliphatic alcohols such as butanol, aluminum alcohol, hexanol, octanol, lauryl alcohol, cetyl alcohol, and alicyclic alcohols such as cyclohexanol, methylcyclohexanol, and benzyl alcohol, α-phenethyl alcohol, β- Examples include aralkyl alcohols such as phenethyl alcohol, and dihydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol. It may contain a substituent that does not inhibit the reaction, such as a group, an alkyl group, a halogen atom, or a carboxyl group. The concentration of the nitrite ester used can vary over a wide range, but in order to obtain a satisfactory reaction rate, the nitrite ester should be present in the reaction system at a concentration of at least 2% by weight or more based on the reaction solution. is necessary. The higher the concentration of nitrite ester, the faster the reaction will proceed, so usually
It is preferable to use it at a concentration of 5% by weight or more. The upper limit of the concentration used can be arbitrarily selected so as to obtain the desired reaction rate. In the present invention, as shown in the above reaction formula, nitrite is consumed to produce carbonic acid diester, and nitrogen monoxide is generated in an amount approximately equal to the amount of consumed nitrite. Therefore, if alcohol and a molecular oxygen-containing gas are allowed to coexist in the reaction system, the generated nitrogen monoxide will easily convert into nitrite ester through the reaction with these, and the generated nitrite ester will become the reaction substrate again. Therefore, the yield of the target product can be increased. In addition, the reaction proceeds more smoothly and more quickly when alcohol and molecular oxygen-containing gas are present in the reaction system. For these reasons, it is generally preferable to carry out the present invention in the presence of an alcohol and a molecular oxygen-containing gas. The alcohol used in this case is selected from the alcohol components that are constituents of the nitrite ester, and the molecular oxygen-containing gas may be diluted with an inert gas such as nitrogen, or It may be air. The carbon monoxide used in the process of the invention can be pure or diluted with an inert gas, such as nitrogen, or it can contain small amounts of hydrogen or methane gas. The higher the partial pressure of carbon monoxide in the reaction system, the higher the reaction rate, but since a large amount of by-products tend to be produced, it is necessary that the partial pressure of carbon monoxide be within the range of 0.1 to 3 Kg/cm ² . The catalyst used in the method of the present invention is a platinum group metal or its salts, such as palladium, platinum, iridium, rhodium, and ruthenium, or their nitrates, sulfates, phosphates, and halides. and organic acid salts such as acetate, oxalate, and benzoate. It may also be a palladium complex, and the ligand may be an alkylphosphine such as trimethylphosphine, an arylphosphine such as triphenylphosphine, or an alkylarylphosphine such as diethylphenylphosphine. , or triphenylphosphite. Furthermore, it may be a complex in which =CO, -NO, -CN, halogen, etc. are coordinated. Additionally, these catalysts can be treated with activated carbon, alumina, etc. to facilitate catalyst recovery and prevent catalyst loss.
It is industrially advantageous to use it supported on an inert carrier such as silica, diatomaceous earth, pumice, zeolite, or molecular sieve. The amount of these catalysts used is 0.1 ppm to 2 ppm based on the reaction mixture in terms of metal.
It is sufficient to use % by weight, usually in the range of 10 to 200 ppm. The reaction is usually carried out in a liquid phase within the range of 20 to 150° C., and can be carried out in a batch or continuous manner, but the continuous method is an industrially advantageous method because the heat of reaction can be easily removed. This reaction may be carried out in a solvent inert to this reaction. Suitable solvents include lower fatty acid esters such as ethyl acetate, propyl acetate, butyl acetate, amyl acetate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, dimethyl oxalate, aliphatic dicarboxylic acid diesters such as diethyl oxalate, dipropyl oxalate, dibutyl oxalate, dimethyl succinate, diethyl succinate, and dimethyl adipate; nitrile acids such as acetonitrile and benzonitrile; ketones such as methyl ethyl ketone; Ketals such as 1,1-diethoxycyclohexane, acetals such as acetaldehyde dibutyl acetal, aromatic carboxylic acid esters such as methyl benzoate, ethyl benzoate, and dimethyl phthalate, and dioxane and dibutyl ether. ethers, hydrocarbons such as benzene, toluene, xylene, cyclohexane, n-hexane, other monochlorobenzene, dichlorobenzene, nitrobenzene, acetophenone, alkylsulfone,
Examples include alkyl sulfoxide and methylene chloride. The carbonic acid diester of the target product is also useful as a solvent. Example 1 Add 50 ml of ethyl nitrite to a 300 ml autoclave.
ml, 50 ml of ethanol, and 0.1 g of a powdered catalyst in which 10 wt% of palladium metal was supported on activated carbon were charged, and the temperature was raised while stirring and maintained at about 70°C. Next, a mixed gas consisting of 4 Vol% carbon monoxide, 8 Vol% air and 88 Vol% nitrogen was heated to a reaction pressure of
Aeration was carried out for 0.5 hours at a rate of 200 Nml/min while maintaining the pressure at 25 Kg/cm ² . Examples 2 to 6 In a 200 ml three-necked flask, 50 ml of various nitrite esters, 50 ml of various alcohols, and 0.1 of a powdered catalyst with 10 wt% of palladium metal supported on activated carbon.
g was charged, the temperature was raised while stirring, and the temperature was maintained at a predetermined temperature. Next, a mixed gas of carbon monoxide and air in a volume ratio of 5:2 was bubbled through at a rate of 700 ml/min for 1 hour under normal pressure. The reaction products in each example were analyzed by gas chromatography. The results are shown in the table below. 【table】

Claims (1)

[Claims] 1 A nitrite ester is subjected to a liquid phase reaction with carbon monoxide in the presence of a platinum group metal or its salt under conditions of a carbon monoxide partial pressure of 0.1 to 3 Kg/cm ² and a temperature of 20 to 150°C. A method for producing carbonic acid diester.