JPS58154520A - Preparation of ethylene glycol - Google Patents

Abstract

PURPOSE:To prepare ethylene glycol in one step, by irradiating formaldehyde with light under normal temperature and pressure, if necessary in the presence of a ketone compound and/or a rhodium compound. CONSTITUTION:Formaldehyde is irradiated with light (preferably white light radiation from mercury lamp) under normal temperature and pressure to obtain ethylene glycol. The yield of ethylene glycol can be increased by carrying out the reaction in the presence of a ketone compound (e.g. acetone, benzophenone, etc.) and/or a rhodium compound (e.g. chlorotristriphenylphosphine rhodium (I)complex). The formaldehyde is used preferably as a solution, and the formalin (solution) available at a low cost is sufficient for the purpose. The solution may contain methanol as a stabilizer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a completely new process for producing ethylene glycol from formaldehyde.

More specifically, the present invention relates to a method for producing ethylene glycol from formaldehyde in a single step by photochemical reaction. Ethylene glycol is used as a raw material for polyester fibers and films, as an intermediate for organic chemicals,
It is a basic chemical product that is industrially important and in high demand as an organic solvent, antifreeze, coolant, etc. This ethylene glycol is currently produced by a petrochemical method using ethylene as a raw material. However, due to the soaring price of crude oil and the depletion of petroleum resources, there is a need to switch to raw materials for petrochemical derivatives.

As raw material sources other than petroleum, synthetic gas which is easily available from natural gas or coal containing methane as a main component, and compounds having one carbon number such as methanol and formaldehyde derived therefrom are useful.

For example, a method for producing ethylene glycol directly from synthesis gas using a rhodium catalyst (Japanese Unexamined Patent Publication No. 50-32117,
51-32507, etc.), a method using formaldehyde and synthesis gas as raw materials (JP-A-51-128903, JP-A-53-53607, etc.), and a method in which a secondary acetal of formaldehyde and synthesis gas are reacted to produce ethylene glycol monomer. A method of obtaining ethylene glycol by converting it into an ether and then hydrolyzing it (Japanese Unexamined Patent Publication No. 56-118026), solvolyzing a polymer obtained by copolymerizing formaldehyde and carbon monoxide with alcohol to obtain a glycolic acid ester; Methods for producing ethylene glycol by hydrogenation are known (e.g., Japanese Patent Application Laid-open No. 106408/1983), but all of these methods require the reaction to be carried out in the presence of high pressure carbon monoxide or synthesis gas. In addition, some methods require many reaction steps, which should be improved.

Alternatively, copper in concentrated sulfuric acid is reacted with formaldehyde and carbon monoxide at room temperature and pressure in the presence of carbon, then treated with methanol to produce glycolic acid, which is then hydrogenated to obtain ethylene glycol (Ainari). Yoshie, Hiroshi Sano, Catalyst 23, 48 (1981), etc., but this method also involves many reaction steps and uses a large amount of sulfuric acid, which is difficult due to its corrosivity and troublesome disposal.

As a result of repeated studies to overcome the drawbacks and problems of conventionally known ethylene glycol production methods, the inventors of the present invention succeeded in producing a one-step reaction of direct ethylene by irradiating formaldehyde with light at room temperature and normal pressure. It was found that glycol can be obtained, and that the yield thereof is increased in the presence of a ketone compound, a rhodium compound, or both, and based on this finding, the present invention was accomplished.

That is, the present invention relates to a method for producing ethylene glycol, which is characterized by irradiating formaldehyde with light, and a method for producing ethylene glycol, which is characterized by irradiating formaldehyde with light in the presence of a ketone compound or in the presence of a rhodium compound. The present invention provides a method for producing ethylene glycol, which is characterized in that formaldehyde is irradiated with light in the presence of a ketone compound and a rhodium compound.

Formaldehyde used in the present invention may be in any form, but it is preferable to use it in the form of a solution. Generally, inexpensively available formalin (aqueous solution) is sufficient,
This solvent may contain methanol as a stabilizer, and does not necessarily need to be pure formaldehyde.

The ketones used in the present invention are represented by the general formula (R1 and R2 represent an aliphatic group, an alicyclic group, or an aromatic group), and specific examples of preferable ones include acetone, 2-butane 3-pentanone, , acetophenone, benzophenone, etc. The ratio of ketone and formaldehyde to be used can be determined arbitrarily, but preferably the ketone/formaldehyde (molar ratio) ratio is 0 to 10.

The rhodium compound used in the present invention is not particularly limited, but soluble compounds are preferred. Preferred is chlorotristriphenylphosphine rhodium (I
) Complex chlorocarbonylbistriphenylphosphine Rhodium (I) I-valent mononuclear complex coordinated with phosphine, halogen, carbon monoxide, etc., such as the complex, or rhodium acetate dimer {Rh2(O2CCH3)4
}, III-valent dinuclear complexes such as rhodium acetylacetonate {Rh(C5H702)3}, hexalodium hexadotyl carbonyl {Rh6
An O-valent dinuclear complex such as (CO)16} is preferable. There is no particular restriction on the amount of this rhodium compound used, but 5. O
A range of x10-2 to 1 x10-3 mmol/mol formaldehyde is preferred. In the method of the present invention, formaldehyde, a ketone compound, and a rhodium compound are usually mixed in an air atmosphere, but they are mixed in an oxygen atmosphere.

As the irradiation light in the method of the present invention, a wide range of white light or monochromatic light ranging from ultraviolet light to visible light can be used, but white light generated from a mercury lamp is preferably used.

The light irradiation time is not particularly limited and varies depending on the irradiation conditions such as the intensity of the light source and the irradiation distance, the reaction capacity, etc. In the method of the present invention, light irradiation is usually carried out at room temperature, but may be carried out under heating or cooling if necessary.

In this way, according to the method of the present invention, formaldehyde is optionally added in the presence of a ketone compound and a rhodium compound.
By irradiating light, ethylene glycol can be produced in a one-step reaction at room temperature and pressure, and is of great significance as it provides a method for producing ethylene glycol based on a completely new reaction system.

Next, the present invention will be explained in more detail based on examples.

Example 1 200 ml of a formalin aqueous solution (containing 35% formaldehyde) was placed in a 300 ml glass internal irradiation type reaction vessel and stirred for 30 minutes under an air atmosphere.

Next, while stirring the reaction solution, light irradiation was started using a 100 W high pressure mercury lamp. The reaction temperature was kept at 20°C. Analysis of the reaction solution 5 hours after the start of irradiation revealed that 1.5 ml (26.8 mmol) of ethylene glycol had been produced.

Example 2 190 ml of formalin aqueous solution (containing 35% formaldehyde) was placed in a 300 ml glass internal irradiation type reaction vessel.
10 ml of acetone was charged and stirred for 30 minutes under an air atmosphere. Next, while stirring the reaction solution, light irradiation was started using a 100 W high pressure mercury lamp.

The reaction temperature was kept at 20°C. As a result of analyzing the reaction solution 5 hours after the start of irradiation, 3.32 ml of ethylene glycol (
59.4 mmol) was produced.

Example 3 160 ml of formalin aqueous solution (containing 3.5% formaldehyde) was placed in a 300 ml glass internal irradiation type reaction vessel.
, 40 ml of acetone was charged, and the mixture was stirred for 30 minutes under an air atmosphere. Next, while stirring the reaction solution, light irradiation was started using a 100 W commercial mercury lamp, and the reaction temperature was maintained at 20°C. Analysis of the reaction solution 11 hours after the start of irradiation revealed that 4.48 ml (80.1 mmol) of ethylene glycol had been produced.

Example 4 160 ml of formalin aqueous solution (containing 35% formaldehyde) was placed in a 300 ml glass internal irradiation type reaction vessel.
40 ml of acetone and 40 mg (0.041 mmol) of chlorotristriphenylphosphine rhodium were charged and stirred for 30 minutes under an air atmosphere. Next, while stirring the reaction solution, light irradiation was started using a 100 W high pressure mercury lamp. The reaction temperature was kept at 20°C. Analysis of the reaction solution 11 hours after the start of irradiation revealed 5.36 ml of ethylene glycol.
(95.9 mmol) was produced.

Example 5 200 ml of formalin aqueous solution (containing 35% formaldehyde) was placed in a 300 ml glass internal irradiation type reaction vessel.
20 ml of acetone and 40 mg (0.041 mmol) of chlorotristriphenylphosphine rhodium were charged, and the mixture was stirred for 30 minutes under an air atmosphere. Next, while stirring the reaction solution, light irradiation was started using a 100 W high pressure mercury lamp. The reaction temperature was kept at 20°C. As a result of analyzing the reaction solution 5 hours after the start of irradiation, ethylene glycol was found to be 3.476.
ml (62.2 mmol) was produced.

Example 6 360 ml of formalin aqueous solution (containing 35% formaldehyde) was placed in a 500 ml glass internal irradiation type reaction vessel.
40 ml of acetone and 40 mg (0.041 mmol) of chlorotristriphenylphosphine rhodium were charged and stirred for 30 minutes under an air atmosphere. Next, while stirring the reaction solution, light irradiation was started using a 400 W high-pressure mercury lamp.

The reaction temperature was kept at 20°C. Analysis of the reaction solution 5 hours after the start of irradiation revealed that ethylene glycol was 4.48 ml (8
0.1 mmol) was produced.

Claims (2)

[Claims] (1) A method for producing ethylene glycol, which comprises irradiating formaldehyde with light to produce ethylene glycol. (2) A method for producing ethylene glycol, which comprises producing rhodium ethylene glycol in the presence of a ketone compound.