KR810001972B1 - Process for preparing a diester of oxalic acid - Google Patents

Abstract

(CO2H)2 diesters were prepd. by vapor-phase reaction of CO with HNO2 esters at 50-200 ≰C in the presence of solid catalysts carrying Pd or its salts. Thus, 30 L/h CO and 9.85 g/h Bu nitrite were passed over 30 mL 0.92 wt. % Pd/C at 85≰C to give (CO2Bu)2 50.4, Bu2CO3 4.30, PrCHO 16.8 and HCO2Bu 15.9 mmol/h with 53.9% conversion of Bu nitrite.

Description

Manufacturing method of hydroxyl diester

The present invention provides a method for producing a hydroxyl diester by vapor-contacting carbon monoxide and nitrite ester in the presence of a solid catalyst carrying a palladium metal or salt thereof, and (2) in the presence of a molecular oxygen-containing gas or The present invention relates to a method for producing a diester of hydroxide by vapor-phase contact of a nitrogen oxide or a hydrate thereof with alcohol and carbon monoxide to react with an alcohol to produce nitrite ester.

Hydroxide diesters have important uses as synthetic raw materials such as hydroxyl, oxamide, glycols, salt intermediates and medicines.

Conventionally, various catalyst systems, cocatalysts, reaction promoters, and the like have been proposed in a method for producing an acid diester by bringing alcohol and carbon monoxide or molecular oxygen into contact with them in the presence of a white metal catalyst under liquid phase pressure. In fact, none of them had any drawbacks and could not be provided for actual use.

The present inventors carried out various studies with the aim of establishing a manufacturing method of industrially excellent hydroxyl diester with this setting in mind. As a result, nitrogen oxides selected from carbon monoxide and nitrite esters or carbon monoxide and alcohols and nitrogen monoxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen tetraoxide in the presence of a solid catalyst carrying a palladium metal or salt thereof or When the hydrate was introduced into the molecular oxygen-containing gas, if necessary, and vapor-phase contacted at a temperature of 50-200 占 폚, it was found that the diester of hydroxyl can be industrially produced.

The method of the present invention improves the general drawbacks in the carbonylation reaction of alcohols by liquid wett, which has been proposed in the related art, and can produce hydroxyl diesters in an extremely advantageous manner.

That is, the method of the present invention has many advantages as follows.

(1) In the conventionally proposed liquid phase reaction, the hydroxyl diester can be produced at a high selectivity and a high publication yield even under normal pressure or low pressure at which the hydroxyl diester is not substantially produced. Therefore, no expensive high-pressure reactor is required, and the compression power of the raw material is reduced.

(2) Since solid catalysts are used in fixed or fluidized beds, there is no need to provide special equipment for separation of reaction products and catalysts. In addition, since it is a gas phase reaction, there is no dissolution loss of palladium which is frequently observed in the conventional liquid phase reaction.

(3) Solid catalysts have high durability and long life.

In the present invention, the reaction mechanism occurring on the catalyst is not yet fully understood, but the main reaction is the same as the reaction represented by the following equation.

Wherein R is an alkyl group or a cycloalkyl group.

As can be seen from this scheme, nitrogen monoxide in an amount corresponding to the amount of nitrite consumed is generated. Therefore, alcohol and molecular oxygen-containing gas may be introduced therein and reacted to recover it as nitrite ester, and may be circulated and used as a raw material for the production of hydroxyl diester.

The nitrite ester used for this reaction may not necessarily be a form of a nitrite ester, and the raw material which forms a nitrite ester in a reaction system may be used. That is, instead of nitrite ester, it is also useful to use nitrogen oxide selected from alcohol, nitrogen monoxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen tetraoxide, or a hydrate thereof, by introducing a molecular oxygen-containing gas as necessary. As the hydrate of nitrogen oxides, nitric acid, nitrous acid and the like are effective. In these cases, the alcohol provided for use is selected from the components of the alcohol which is a component of the nitrite ester mentioned later.

The catalyst used in the method of the present invention is a palladium metal or salt thereof supported on an inert carrier such as alumina, silica, diatomaceous earth, pumice, zeolite and molecular sieve.

Palladium does not necessarily need to be pure, and precious metals containing palladium as a main component can be used as well. Palladium salts include organic acid salts such as nitrates, sulfates, phosphates, halides and acetates, oxalates and benzoates. Moreover, a palladium complex may be sufficient.

The amount of palladium supported is preferably in the range of 0.01-10% by weight and usually 0.5-2% by weight relative to the support in terms of palladium metal.

The nitrite ester used in the method of the present invention is an ester of saturated monohydric aliphatic alcohol or alicyclic alcohol having 1 to 8 carbon atoms with nitrous acid, and the alcohol component is, for example, methanol, ethanol, n- (and iso-) propanol , aliphatic alcohols such as n- (iso, secondary, tertiary-) butanol, n- (and iso-) amyl alcohol, hexanol, octanol, and cycloaliphatic alcohols such as cyclohexanol, methylcyclohexanol, etc. These alcohols may contain a substituent which does not inhibit the reaction such as alkoxy.

The use concentration of nitrite ester can vary widely, but in order to obtain a satisfactory reaction rate, it is necessary to present the concentration of nitrite ester in the raw material gas introduced into the reactor to be 1% by volume or more.

The higher the nitrite ester concentration, the faster the reaction proceeds. However, the upper limit of the concentration of the nitrite ester needs to be selected in the range where the liquid phase of the diester hydroxide does not form in the reaction zone, and is usually used in the range of 5-20% by volume.

The carbon monoxide used in the method of the present invention may be diluted with pure or inert gas such as nitrogen. In the reaction zone, carbon monoxide has a wide range of concentrations, and a range of 20 to 90% by volume is usually selected.

When the process of the present invention is carried out using a relatively high concentration of nitrite ester, it proceeds sufficiently fast even at a considerably low temperature, and the lower the reaction temperature, the less by-products are produced. However, even in this case, if the liquid phase is produced in the reaction zone, the reaction is suppressed, and therefore it is advantageous to perform the reaction at a relatively low temperature while maintaining the desired disclosure yield. The reaction temperature is usually preferably in the range of 50-200 ° C. The reaction pressure may be any range in which no liquid phase is formed in the reaction zone, and is usually sufficient at normal pressure. Depending on the raw material used, it may be slightly pressurized or kept at a slightly reduced pressure.

The method of the present invention is carried out using a fixed bed or fluidized bed reactor, and the contact time of the source gas with the solid catalyst is preferably 10 seconds or less, particularly in the range of 0.2-5 seconds.

Examples of the present invention are listed as follows. In Tables 1 to 4, BN is n-butyl nitrite, DBO is di-butyl hydroxy, DBC is di-butyl carbonate, BA is n-butylaldehyde, EF Is formic acid n-butyl, BL is n-butyl aldehyde di n-butyl acetal, BuOH is n-butylol.

Example 1-6

Into a reaction tube of a glass product having an internal diameter of 25 mm and a length of 550 mm, 18.5 g (30 ml) of a 0.95 mm diameter carbon particulate catalyst carrying 0.92% by weight of palladium was charged. Furthermore, the top was filled with a 150 mm raschig's ring. The reaction tube was fixed vertically, and an electric heater wound with a coil was installed outside thereof to adjust the temperature inside the catalyst bed to a predetermined temperature by heating. Raw material nitrite n-butyl was supplied to the vaporizer heated by the oil bath with the fixed-quantity pump.

Alternatively, carbon monoxide was fed to the vaporizer at a predetermined flow rate and then introduced into the catalyst bed with n-butyl nitrite vaporized from the top of the reaction tube. The reaction product that passed through the catalyst bed was collected in a trap cooled with ice water, and then the trap was cooled with dry ice-methanol and analyzed by gas chromatography. The results are shown in Table 1.

TABLE 1

Most of the impurities are BuOH.

Example 7-10

In the atmospheric gas phase reactor used in Example 1-6, 6.22 g (10 ml) of a 0.95 mm diameter Kaven granular catalyst carrying 0.92% by weight of palladium was charged into a reaction tube, and then a predetermined amount of nitrous acid n- was used as a raw material. The experiment was carried out in the same manner using a mixture of butyl and n-butanol and further introducing a predetermined amount of molecular oxygen and carbon monoxide. The results are shown in Table 2.

TABLE 2

[Examples 11 and 12]

A cylindrical pelletizer having a diameter of 3 mm and a height of 4 mm in which the reaction tube was loaded with 0.5 wt% of palladium in the atmospheric gas reactor used in Example 1-6 (manufactured by Engelhard Co., Ltd.) 8.62 After g (10 ml) was charged, an experiment was conducted in which n-butanol, nitrogen monoxide, molecular oxygen and carbon monoxide were introduced into the catalyst layer in the gas phase as raw materials.

Example 13

In the atmospheric vapor phase reactor used in Example 1-6, the reaction tube was filled with 6.2 g (10 ml) of a granular catalyst having a diameter of 0.95 mm and carrying 0.92 wt% of palladium, followed by n-butanol and carbon monoxide as 64 raw materials. An experiment was conducted in which% aqueous nitric acid solution was introduced into the catalyst layer in a gaseous state. The results for Examples 11-13 are shown in Table 3.

TABLE 3

Example 14-16

Made of stainless steel (SVS 304), a pressure-resistant reaction tube having an internal diameter of 25 mm and a length of 700 mm was charged with 6.15 g (10 ml) of a Carbane granular catalyst of 0.95 mm in diameter carrying 0.92 wt% of palladium. Furthermore, the top was filled with a racing ring made of glass 200 mm high. The filled layer was thus heated to a predetermined temperature from the outside of the tube by a coiled electric heater. The raw material nitrite nitrite was supplied from the reaction tube nozzle using a metering pump, and then heated together with carbon monoxide to vaporize and introduced into the catalyst layer. The reaction liquid was obtained as a result of cooling and then condensing the gas passing through the catalyst bed.

The gas which did not condense was pressure-reduced to normal pressure so that the reaction system may be maintained at predetermined pressure, and it may become predetermined gas flow volume. The reaction solution thus obtained was analyzed by gas chromatography. The results are shown in Table 4.

TABLE 4

Example 17-24

In the atmospheric vapor phase reactor used in Example 1-6, the reaction tube was charged with a catalyst carrying a predetermined palladium, and then carbon monoxide and a predetermined nitrite ester were introduced therein to react the reactants. The reaction product was collected by cooling and analyzed by gas chromatography. The results are shown in Table 5.

TABLE 5

Claims (1)

As described above in the main text, carbon monoxide and nitrite esters are subjected to gas phase contact at a temperature of 50-200 ° C. in the presence of a solid catalyst carrying a palladium metal or a salt thereof.