JPS5920658B2 - Manufacturing method of glycolic acid ester - Google Patents

Description

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

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

One known industrial method for producing glycolic acid esters is to react formaldehyde and carbon monoxide to produce polyglycolide in the first step, and react this polyglycolide with alcohol in the second step. (Japanese Unexamined Patent Publication No. 71016/1983). In this method, both the first step and the second step can be carried out in the presence of an acid catalyst, but since the reaction conditions and acid catalyst concentration conditions are different in the two steps,
The reaction mixture obtained in the first step is generally subjected to separate treatment without performing both steps consecutively. Then, alcohol is added to the glycolide obtained through this separation process and a reaction is carried out. For example, the above-mentioned Japanese Patent Application Laid-open No. 53-
In Japanese Patent No. 71016, a reaction mixture of formaldehyde and carbon monoxide is cooled and separated into a solid content with a reduced sulfuric acid catalyst content and a liquid content. Then, this solid content is reacted with alcohol as it is, or after further washing with water, a small amount of sulfuric acid catalyst is added again and reacted with alcohol. However, the above method
Since separation treatment is performed between the first step and the second step, this method cannot yet be said to be industrially advantageous.

Furthermore, the catalyst is still not satisfactory in terms of catalytic activity. Although it is clear that a method in which the first step and the second step are carried out continuously without requiring a separation treatment step is more desirable, such a continuous method has not yet been developed. The inventor of the present invention
As a result of intensive research to develop a method in which the reaction mixture from the process can be used as a raw material in the second step without separation and reacted with alcohol as it is, we have identified an acid catalyst to be used in the first step. Along with choosing the one.

When specifying the amount to be used, it was discovered that the reaction mixture from the first step can be directly reacted with alcohol in the second step with good yield, and the present invention was completed. That is, according to the present invention, fluoroantimonic acid,
A catalyst selected from chlorosulfonic acid, pyrosulfuric acid and fluoroboric acid per mole of raw material formaldehyde component,
After reacting carbon monoxide with formaldehyde or a formaldehyde polymer that produces formaldehyde by depolymerization using a proportion of 0.2 to 0.0001 mol,
A method for producing a glycolic acid ester is provided, which comprises reacting the obtained reaction mixture with an alcohol without separating the catalyst contained therein.

In the present invention, the catalyst used in the first step also acts as a catalyst in the second step, and in order to obtain an effective catalytic effect in both steps and to carry out the reaction continuously, the type of catalyst used must be selected. It is necessary to specify the amount used. According to the research of the present inventors, a catalyst selected from fluoroantimonic acid, chlorosulfonic acid, pyrosulfuric acid, boron trifluoride, and fluoroboric acid is used, and a formaldehyde component of 1
0.2 to 0.0001 mole to mole, preferably 0
．． When adopting a proportion of 1 to 0.001 mol. In the second step, there is no need to separate the reaction mixture from the first step.
It has been found that it can be supplied to the process and also that good reaction results can be obtained. If the amount of catalyst exceeds the above range, problems such as an increase in by-products and difficulty in separating the product and catalyst may occur, which is undesirable.On the other hand, if the amount falls below the above range, the catalyst may not be effective. The effect will no longer be obtained. In addition, in the case of chlorosulfonic acid and pyrosulfuric acid catalysts, a catalyst obtained by adding an equimolar amount or less of acetyl chloride to these catalysts can also be used. As the formaldehyde component, in addition to formaldehyde monomers, formaldehyde polymers that can be depolymerized to give formaldehyde, such as trioxane, tetraoxymethylene, paraformaldehyde, and polyoxymethylene, can be used.Methyl is the alcohol. Monohydric aliphatic alcohols such as alcohol, ethyl alcohol, butyl alcohol, allyl alcohol, and octyl alcohol are used.

The amount of alcohol used may range from equimolar to 20 times the molar amount of formaldehyde. In the first step,
Carbon monoxide and formaldehyde are reacted in the presence of a specific amount of the catalyst described above, and the reaction in this case is usually carried out at a pressure of 20 to 500 kg/Cri! Above, usually 30-400
kg/d1 at a temperature of 80-210°C.

The reaction between carbon monoxide and formaldehyde can be carried out without a solvent, but if necessary, it can be carried out in a solvent inert to the reaction.
For example, the reaction may be carried out in a solvent such as dichloromethane, chloroform, or dichloroethane. The reaction mixture containing the catalyst obtained from the reaction of carbon monoxide and formaldehyde is
In the second step, alcohol is added to this and reacted without performing a separation process.

The reaction between the reaction mixture and the alcohol is carried out at 80-160°C. In this case, 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. In the second step, the coexistence of unreacted carbon monoxide in the reaction system causes alkoxyacetic ester by-products, which reduces the recovery rate of formaldehyde and the selectivity of glycolic acid ester. The glycolic acid ester obtained by the present invention can be obtained by distilling the reaction solution obtained from the second step.

Next, the present invention will be described in more detail with reference to Examples.

Example 1 A stainless steel autoclave was charged with 10.09 mmol of paraformaldehyde (purity 94%, 313.3 mmol in terms of formaldehyde), 30 ml of dichloromethane, and 13.9 mmol of chlorosulfonic acid in an atmosphere of carbon monoxide, and then 79 kg/ml of paraformaldehyde was charged at room temperature. Carbon monoxide was added until D.

Next, the temperature was raised to 175° C. while stirring, and reaction was carried out for 2 hours. After the reaction, unreacted carbon monoxide was discharged, methanol 125a 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,
Analysis of the reaction solution by gas chromatography revealed that 290.2 mmol of methyl glycolate was produced. Other components of the reaction solution were dimethyl diglycolate (5.8 mmol), formaldehyde, and formaldehyde acetal. The selectivity of methyl glycolate was 98.0%. Example 2 A reaction was carried out in the same manner as in Example 1 except that 5.1 mmol of chlorosulfonic acid was used, and 269.3 mmol of methyl glycolate was obtained.

The selectivity of methyl glycolate was 97.0%. Example 3 66k at room temperature using 8.5 mmol of fluoroboric acid
Add carbon monoxide until g/CTl and reduce the reaction temperature to 1.
The reaction was carried out in the same manner as in Example 1 except that the temperature was 30°C, and 251.5 mmol of methyl glycolate was obtained.

Example 4 Paraformaldehyde 1 in a stainless steel autoclave
0.09 (purity 94%, formaldehyde equivalent: 313.
3 mmol), 30 ml of dichloromethane and 5 ml of pyrosulfuric acid.
．． 0 mmol was charged under a carbon monoxide atmosphere, and further carbon monoxide was added at room temperature until the concentration reached 40k9/d.

Next, the temperature was raised to 175° C. while stirring, and the reaction was carried out for 2 hours. After the reaction, unreacted carbon monoxide was discharged, 125 ml of ethanol 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, the reaction solution was analyzed by gas chromatography and it was found that 215.2 mmol of ethyl glycolate was produced. Example 5 5.0 mmol of pyrosulfuric acid and 5.0 mmol of acetyl chloride as catalysts.
0 mmol and methanol 1 for alcoholysis.
The reaction was carried out in the same manner as in Example 4 except that 25 ml of methyl glycolate was used, and 264.8 mmol of methyl glycolate was obtained.

The selectivity of methyl glycolate was 96.601). Example 6 Paraformaldehyde 1 in a stainless steel autoclave
0.09 (purity 94%, formaldehyde equivalent: 313.
3 mmol), 30 ml of dichloromethane, and 5.0 mmol of fluoroantimonic acid were charged under a carbon monoxide atmosphere, and further carbon monoxide was added at room temperature until the amount reached 40 kg/(7i1).

Next, the temperature was raised to 100°C while stirring, and the reaction was carried out for 40 minutes. After the reaction, unreacted carbon monoxide was discharged, 125 ml 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,
When the reaction solution was analyzed by gas chromatography, it was found that 227.0 mmol of methyl glycolate was produced.

Claims (1)

[Claims] 1 A catalyst selected from fluoroantimonic acid, chlorosulfonic acid, pyrosulfuric acid, and fluoroboric acid is added in an amount of 0.2 to 0.0001 per mole of raw material formaldehyde component.
After reacting carbon monoxide with formaldehyde or a formaldehyde polymer which produces formaldehyde upon depolymerization using molar proportions, the resulting reaction mixture is
A method for producing a glycolic acid ester, which is characterized by reacting the catalyst contained therein with an alcohol without separating it.