JPS593451B2 - Manufacturing method of ethylene glycol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for efficiently producing ethylene glycol.

More specifically, the method of the present invention involves reacting formaldehyde disecondary alkyl acetal with synthesis gas to obtain a secondary alkyl monoether of ethylene glycol, which is then hydrolyzed to obtain ethylene glycol in good yield. Regarding the method. Ethylene glycol is an industrially important basic compound as a raw material for polyester, an organic solvent, a nonvolatile antifreeze agent, or a coolant.

0 Currently, ethylene glycol is manufactured by a petrochemical method using ethylene as a raw material, but there are other known methods for manufacturing it using carbon number 1 (Cl) compounds such as -carbon oxide and formaldehyde as raw materials. There is.

15 One of the methods is to directly produce ethylene glycol from synthesis gas in the presence of a rhodium catalyst (Japanese Patent Application Laid-open No. 52-42809);
Since it is necessary to carry out the process under pressure of 000 atmospheres or more, it is difficult to implement it industrially.

In addition, '0 A method of producing glycolic acid by reacting formaldehyde with carbon monoxide, esterifying the glycolic acid to convert it into a glycolic acid ester, and then hydrogenating the glycolic acid ester to obtain ethylene glycol (
JP-A No. 54-106408) has been proposed, but this method is not suitable for industrial use because it requires a high-pressure reaction with carbon monoxide using a strong acidic substance such as hydrofluoric acid as a catalyst. There are still problems in implementation. Furthermore, a method of reacting formaldehyde with synthesis gas to obtain ethylene glycol in 30 stages (JP-A-51-128903, JP-A-51-128903;
No. 3-53607) is known, but this method has the drawback of extremely low selectivity for ethylene glycol, and the yield of ethylene glycol from formaldehyde is only 3540% or less.

The present inventors have conducted extensive studies to overcome the drawbacks and problems of the previously known ethylene glycol production methods, and as a result, have synthesized formaldehyde disecondary alkyl acetal using a cobalt compound as a catalyst. It was discovered that a secondary alkyl monoether of ethylene glycol can be obtained by reacting it as a gas, and that the desired ethylene glycol can be efficiently obtained by hydrolyzing this.Based on this knowledge, the present invention was made. Ivy.

That is, the present invention involves reacting formaldehyde disecondary alkyl acetal with a mixed gas of carbon monoxide and hydrogen in the presence of cobalt carbonyl to obtain a secondary alkyl monoether of ethylene glycol, which is further hydrolyzed. The present invention provides a method for producing ethylene glycol.

Conventionally, a method for producing an alkyl monoether of ethylene glycol by reacting an alkyl acetal of formaldehyde with synthesis gas in the presence of cobalt and a trivalent organic phosphorus compound (Japanese Unexamined Patent Publication No. 71408/1989) is known; The alkyl acetals used in the examples were limited to primary alkyl acetals;
Even in that specification, alkyl acetals other than primary are not described.

The present inventors have intensively investigated the use of secondary alkyl acetals as alkyl acetals, and have found that secondary alkyl acetals react particularly easily with synthesis gas in the presence of a cobalt carbonyl catalyst, resulting in secondary alkyl cellosolves. It was found that the reaction rate of TQ secondary alkyl acetal and synthesis gas is about 10 times that of primary alkyl acetal and synthesis gas under the same conditions.

Comparative Example: When the reaction in Experiment Taki 2 in Table 1 of Example 1 was carried out under the same conditions using formaldehyde di-normal propyl acetal instead of formaldehyde diisopropyl acetal, the yield of normal propyl cellosolve was 9.7. It is only %. Further, when a similar reaction was carried out using ethyral, the yield of ethyl cellosolve was only 4.0%. In this way, in the reaction between primary alkyl acetal and synthesis gas, when only cobalt carbonyl is used as a catalyst, the yield of primary alkyl cellosolve is extremely low, and in the conventional method, in addition to cobalt, a trivalent organic phosphorus compound is By adding , primary alkyl cellosolve can be obtained for the first time with a yield of 70% or more, but the method of the present invention uses secondary alkyl acetal as a raw material, which reacts extremely easily with synthesis gas. For,
Unlike the conventional method, this method does not require any additives such as trivalent organic phosphorus compounds, and has the characteristic that secondary alkyl cellosolve can be obtained in good yield using only cobalt carbonyl as a catalyst. Next, when the reaction in Experimental Waterfall 5 in Table 2 of Example 1 was carried out using primary butyl cellosolve instead of isopropyl cellosolve, the yield of ethylene glycol was 1.1%.
It was nothing more than a simple thing.

As described above, the reaction between secondary alkyl cellosolve and water according to the method of the present invention proceeds easily, but the reaction between primary alkyl cellosolve and water is extremely difficult.

The method of the present invention can be expressed by the following two-stage reaction formula.

(R1 and R2 in the formula are each an alkyl group such as a methyl, ethyl, or propyl group, and R and R2 may be the same or different from each other.

) The molar ratio of carbon monoxide and hydrogen in the mixed gas used in the method of the present invention is usually CO:H2 = 1:10 to 10:1, preferably in the range of 1:3 to 3:1.

The pressure of this mixed gas (synthesis gas) is preferably 50 to 300 atmospheres. In the present invention, the catalyst for the reaction with the synthesis gas in the first stage is a cobalt carbonyl compound or a cobalt compound capable of forming cobalt carbonyl under the reaction conditions, such as cobalt metal, cobalt oxide, or cobalt carbonate, cobalt acetate, Cobalt salts such as cobalt sulfate can be used.

The amount of the catalyst to be used is not particularly limited, but is in the range of 2 to 0.002 mol% in terms of cobalt, based on the acetal raw material commonly used. Although this reaction with synthesis gas can proceed without a solvent, it is preferably carried out using a hydrocarbon solvent such as benzene, toluene, xylene, cyclohexane, hexane, heptane, and liquid paraffin.

The hydrolysis reaction of ethylene glycol monoether in the second stage can be carried out in the presence of a known catalyst, for example, an acid catalyst such as sulfuric acid or zinc chloride, but is not limited thereto. Solid acid catalysts such as alumina can also be used. The reaction temperature is 200-400℃
A range of is preferred. The method of the present invention can be carried out in either batch or continuous reaction mode, and products and catalysts can be easily separated and recovered from the reaction solution by applying known methods such as distillation. It can be carried out.

According to the method of the present invention, ethylene glycol can be easily produced from formaldehyde acetal and synthesis gas with excellent selectivity, high yield, and the significance of the method of the present invention as an industrial implementation method is big. Next, the present invention will be explained in more detail based on examples.

Example 1 Formaldehyde diisopropyl acetal [(CH2(0CH(CH3)2)2) 16.57 ml was placed in a 300 ml stainless steel autoclave with electromagnetic vertical stirring.
(0.125m01), 80y of toluene, and a predetermined amount of dicobalt octacarbonyl CO2 (CO)8,
After replacing the air in the vessel with a mixed gas of O:H2-1:1 (molar ratio), a mixed gas of the same composition was injected and the temperature was raised to reach the predetermined reaction temperature. Pressure 200kg
/C! ILVC. I adjusted it so that

Thereafter, the pressure was maintained at 200 kg/CTrL by replenishing a mixed gas of the same composition, and the reaction was carried out at a predetermined temperature. After the reaction, the autoclave was cooled and the product was taken out and analyzed. The results are shown in Table 1. Next, stainless steel 1
In a 00W 1t autoclave, wasopropyl cellosolve 26r (0.25m01) obtained above and water 9V (
After charging 0.5m01) and a catalyst and purging the inside of the vessel with nitrogen, the temperature was raised to 300°C and the inside of the vessel was maintained at this temperature for reaction. At the end of the reaction, the pressure inside the vessel is 85-8
It increased to 8 kg/Crli. After the reaction was completed, the autoclave was cooled, and the resulting solution was taken out and analyzed. The results are shown in Table 2. However, when a solid catalyst was used, the liquid phase components adhering to the solid catalyst after use were washed out with acetone and added to the product solution for analysis. As can be seen from the results of Examples 3 and 4, according to the method of the present invention, ethylene glycol can be obtained from formaldehyde diisopropyl acetal, carbon monoxide, hydrogen and water in a yield of 76% (based on acetal). Example 2 The 300 me capacity autoclave described in Example 1 was
Formaldehyde di-class butyl acetal i1 (CH2
(0CH [ )21110.125m011 toluene 80V and dicobalt octacarbonyl 0.2mm01
As a result, the conversion rate of formaldehyde di-butyl acetal was 92.8%, and the yield (selectivity) of secondary butyl cellosolib from the reacted acetal was carried out under the same conditions as in Experiment 3 in Table 1. was 76.4%.

Next, 10f of secondary butyl cellosolve and 4.5t of water were obtained.
(0.25 m01) and silica-alumina (silica 10
%) 10r was charged into the 100ml autoclave described in Example 1, and the experiments shown in Table 2 were carried out. As a result of reaction under the same conditions as /F65, the yield of ethylene glycol from secondary butyl cellosolve was 70.5%. Example
3 Into the 100 m2 autoclave described in Example 1, add 2511 Lt (19 r) of silica-alumina and 2 m of water.
After charging 01 (361) and replacing the inside of the vessel with nitrogen, 26
The temperature was raised to 5°C.

At this time, the pressure inside the vessel reached 24 atm. Next, 0.125m01 (13t) of isopropyl cellosolve was pumped into the autoclave, and reacted at 265°C for 1 hour (at this time, the pressure inside the vessel reached 37 atm), and then the contents of the autoclave were pumped through the autoclave's offshore pipe. The entire solution was taken out from the bottom of the vessel, and the liquid product was analyzed by gas chromatography. As a result, the conversion rate of isopropyl cellosolve was 53%, the yield of ethylene glycol from the reacted isopropyl cellosolve was 99%, and the yield of isopropanol was 60%. The reason for the low yield of isopropanol is that isopropanol is dehydrated to produce propylene. When the product is distilled, isopropanol is first distilled out as an azeotrope with water (at 80°C
), unreacted isopropyl cellosolve was then distilled off as an azeotrope with water (98°C), and 47 ethylene glycol was obtained as a distillation residue.

Example 4 The reaction was carried out in exactly the same manner as in Example 1 Table 1 Experiment/F6l except that a mixed gas of C0:H2=1:2 (molar ratio) was used and the reaction was carried out at a pressure of 300 kg/(V7!). Allowed time to react.

As a result, the conversion rate of acetal was 100%, the yield of isopropyl cellosolve (MOl%) was 76.4%, and the yield of methyl impropyl ether (MOl%) was 11.5%.
It was hot.

Claims (1)

[Claims] 1 Formaldehyde di-secondary alkyl acetal,
A method for producing ethylene glycol, which comprises reacting with synthesis gas in the presence of cobalt carbonyl to obtain a secondary alkyl monoether of ethylene glycol, which is further hydrolyzed.