JPS6024782B2 - Method for producing glycolic acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a glycolic acid ester from formaldehyde, carbon monoxide and alcohol.

Glycolic acid ester is a useful substance used for various purposes as a chemical raw material, and there is currently a desire to develop an inexpensive industrial method for producing it.

As one of the industrial methods for producing glycolic acid ester,
A method is known in which formaldehyde is reacted with carbon monoxide in a step to first produce polyglycolide, and then in a second step this polyglycolide is reacted with alcohol (Tokukekiseki Publication No. 71016/1986).
In this method, both the first step and the second step are carried out in the presence of an acid catalyst, but since the reaction conditions and acid catalyst concentration conditions of both steps are different, it is not possible to carry out both steps consecutively. If this is not possible, it is necessary to take out the reaction mixture obtained in the first step and perform a separation process. Then, alcohol is added to the polyglycolide obtained through this separation treatment to perform a reaction. That is, the reaction mixture of formaldehyde and carbon monoxide is cooled and separated into a solid component with a reduced sulfuric acid catalyst content and a liquid component, and then the solid component is directly reacted with alcohol, or the solid component is further reacted with water. After washing with water, a small amount of sulfuric acid catalyst is added again and reacted with alcohol. However, such
Since this method requires a separation treatment step between the first and second steps, it cannot be said to be a particularly advantageous method from an industrial perspective.

Although it is clear that a method in which the first step and the second step can be performed continuously without requiring a separation treatment step is more desirable, such a method has not yet been developed. The present inventors have conducted extensive research to overcome the drawbacks of this conventional method and have developed a method that allows the reaction product from the first step to be directly carried out in the second step without being separated. We have discovered that if a specific catalyst is selected as the catalyst for the first step, the reaction product from the first step can be efficiently reacted with alcohol in the second step, and based on this knowledge, we have completed the present invention. .

That is, the present invention involves reacting carbon monoxide with formaldehyde or a formaldehyde polymer that produces formaldehyde through depolymerization in the presence of a catalyst selected from the group consisting of methyl sulfuric acid, magic methyl, fluorosulfonic acid, and magic acid. The present invention provides a method for producing a glycolic acid ester, which is characterized in that a carbon oxide/formaldehyde copolymer is produced and the reaction product is directly reacted with alcohol without being separated from the reaction system.

In the present invention, the catalyst used in the first step also exhibits catalytic action in the second step.

The amount of this catalyst used is, per 1 mole of formaldehyde,
The range of 0.1 to 0.001 mol is preferred. If there is too much catalyst, there will be problems such as an increase in by-products and the time required to separate the catalyst from the product, while if there is too little, it will not be possible to obtain an effective catalytic effect. Examples of the formaldehyde used in the present invention include formaldehyde monomers as well as formaldehyde polymers that depolymerize to give formaldehyde, such as trioxane, tetraoxymethylene, /graformaldehyde, and polyoxymethylene.

In addition, examples of alcohol include methyl alcohol, ethyl alcohol, propyl alcohol, phthyl alcohol,
Monohydric aliphatic alcohols such as octanol are used.

In the present invention, the first step is carried out by reacting carbon monoxide and formaldehyde in the presence of the catalyst described above.

In this case, the reaction molar ratio of carbon monoxide and formaldehyde (
CO/CH20) is preferably 1 or more. The reaction pressure is usually 5k9/mass or more, the reaction temperature is in the range of 80 to 210oo,
Preferably it is carried out at 90 to 190 qo. reaction pressure is 5
If it is less than k9/k, the reaction will take a long time, which is not preferable. Moreover, if the reaction temperature exceeds 21 mm, catalyst decomposition and side reactions tend to occur, which is undesirable. If it is less than 8,000, the reaction takes a long time, which is not preferable.

The reaction in the first step can be carried out in a solvent inert to the reaction, such as dichloromethane, chloroform, dichloroethane, or the like, but it can also be carried out without a solvent.

Next, in the second step of the present invention, the reaction product obtained from the reaction of carbon monoxide and formaldehyde, that is, the reaction mixture containing the carbon monoxide/formaldehyde copolymer and the catalyst, is not subjected to any special separation treatment. It consists of adding alcohol and reacting. In this case, the amount of alcohol used is preferably in the range of equimol to 2 sonic moles relative to the carbon monoxide consumed in the reaction of carbon monoxide and formaldehyde in the first step. If the amount of alcohol is too large, it will take time to separate the glycolic acid ester. The reaction temperature in this second step is preferably 80 to 21 pi. reaction temperature is 80
If the temperature is below ℃, a long time is required for the reaction. If it exceeds 210 qo, side reactions are likely to occur.

In this second step, if unreacted carbon monoxide from the first step coexists in the reaction system, it may cause creation of alkoxyacetic ester.

Therefore, it is preferable that unreacted carbon monoxide present in gaseous form in the reaction system or reaction vessel space be removed from the reaction system by purging with air, nitrogen, or the like. Second
For example, by distilling the reaction solution obtained from the process,
The target glycolic acid ester can be easily separated.

As described above, according to the method of the present invention, glycolic acid ester can be produced continuously and extremely efficiently from carbon monoxide, formaldehyde, and alcohol, and glycolic acid ester can be produced industrially and inexpensively. This is suitable as a manufacturing method.

Next, the present invention will be explained in more detail based on examples. Example 1 In a stainless steel autoclave (300 units), 10.0 units of paraformaldehyde (94% purity, 313.3 mmol in terms of formaldehyde), 40 units of dichloromethane, and 4 mmol of magic acid were charged in a carbon monoxide atmosphere. Then, carbon monoxide was added to the mixture until it reached 33k9/kg at room temperature.

Next, the temperature was raised to 150° C. while stirring, and reaction was carried out for 30 minutes. Next, after discharging unreacted carbon monoxide,
125' of methanol was added to the contents of the autoclave, and the reaction was carried out at 150° C. for 3 hours while stirring. After the reaction was completed, the reaction solution was analyzed by gas chromatography, and it was found that 2557 mmol of methyl glycolate had been produced. Other components in the reaction solution were dimethyl diglycolate (17.6 mmol), formaldehyde, and formaldehyde acetal. Example 2 In a stainless steel autoclave similar to Example 1, 10.0 mol of paraformaldehyde (94% purity, 3133 mmol of formaldehyde), 30 ml of dichloromethane, and 11 mmol of dimethyl sulfuric acid as a catalyst were placed in a carbon monoxide atmosphere. Charged below and then added carbon monoxide to 69k9/base at room temperature.

Next, the temperature was raised to 175° C. while stirring, and the reaction was carried out for 2 hours. After the reaction was completed, the reaction solution was analyzed in the same manner as in Example 1, and it was found that 199.4 mmol of methyl glycolate and 5.6 mmol of dimethyl diglycolate were obtained. Example 3 In a stainless steel autoclave similar to Example 1, 10.0 mmol of paraformaldehyde (94% purity, 313.3 mmol in terms of formaldehyde), 30 mmol of dichloromethane, and 10 mmol of magic methyl monoxide as a catalyst were added. The mixture was charged under a carbon atmosphere and then carbon monoxide was added at room temperature until 62k9' water was obtained.

Next, the temperature was raised to 175° C. while stirring, and the reaction was carried out for 2 hours. After the reaction was completed, the reaction solution was analyzed in the same manner as in Example 1, and it was found that 2504 mmol of methyl glycolate and 15.2 mmol of dimethyl diglycolate were produced. Example 4 Into a stainless steel autoclave similar to Example 1, 10.0 mmol of trioxane and 4 mmol of fluorosulfonic acid as a catalyst were charged in a carbon monoxide atmosphere, and then monoxide was added at room temperature until the concentration reached 55%. Added carbon.

Claims (1)

[Claims] 1. Carbon monoxide/formaldehyde is produced by reacting carbon monoxide with formaldehyde or a formaldehyde polymer that produces formaldehyde through depolymerization in the presence of a catalyst selected from the group consisting of dimethyl sulfuric acid, magic methyl, fluorosulfonic acid, and magic acid. A method for producing a glycolic acid ester, which is characterized in that a copolymer is produced and the reaction product is directly reacted with an alcohol without being decomposed from the reaction system.