CN1175570A - Method and catalyst of synthesis of methyl glycolate - Google Patents

Abstract

A process for synthesizing methyl glycolate includes coupling reaction of methyl formate with formaldehyde in the presence of metal carbonyl sulfate as catalyst at 60-180 deg. C for 1-12 hr, addition of methanol, and decomposing reaction at 60-130 deg. C for 1-2 hr, and features mild process conditions and high yield of product.

Description

Method for synthesizing methyl glycolate and catalyst

The invention relates to a method for synthesizing methyl glycolate and a catalyst, in particular to a reaction process for synthesizing high-yield methyl glycolate by taking methyl formate and formaldehyde as raw materials through two steps and a required sulfuric acid and metal carbonyl compound catalyst, belonging to the synthesis of organic compounds.

Methyl glycolate is widely used for organic synthesis and pharmaceutical synthesis, and is used as an important chemical reaction intermediate: 1) the problem of shortage of raw materials for preparing glycol by a petroleum route is solved by preparing a large amount of chemical product glycol through hydrogenation reduction; 2) the glycolic acid is prepared by hydrolysis, and is widely used as a bactericide and a chemical cleaning agent; 3) preparing methyl glyoxylate by oxidative dehydrogenation, wherein the product glyoxylate of methyl glyoxylate hydrolysis is the main raw material for synthesizing vanillin spice, medical allantoin, acetophenone and the like; 4) ammonolyzing to obtain glycine, and carbonylating to obtain methyl malonate. Therefore, the method develops the problems of preparing methyl glycolate by the reaction of methyl formate and formaldehyde and further preparing glycol and glycollic acid, and has important research and application prospects. In the prior art, methyl glycolate is synthesized from methyl formate and formaldehyde by using an ion exchange resin or a heteropoly acid as a catalyst, and the total yield of methyl methoxyacetate, methyl glycolate, and methoxyacetic acid thereof is only about 50% based on glycolic acid because of low product yield (JP 81-122321). Another common method is the carbonylation of formaldehyde to produce methyl glycolate, where high pressures (300-900 atm) are necessary and the reaction conditions are too severe (u.s, 4016208).

The invention aims to overcome the defects of the prior art and find a novel catalyst and mild process conditions to synthesize high-yield methyl glycolate by using methyl formate and formaldehyde.

The purpose of the invention is realized as follows: the method comprises the steps of taking methyl formate and formaldehyde as raw materials, taking sulfuric acid/metal carbonyl compounds as catalysts, carrying out coupling reaction for 1-12 hours at 60-180 ℃ to obtain coupling reaction liquid, adding methanol, and carrying out decomposition reaction for 1-2 hours at 60-130 ℃ to obtain methyl glycolate, wherein the molar ratio of formaldehyde to methyl formate is 0.1-2, the dosage of sulfuric acid/metal carbonyl compounds is 5-85 g/mol of formaldehyde, and the dosage of methanol is 0.5-3 times (volume) of the coupling reaction liquid.

The sulfuric acid/metal carbonyl compound is prepared by absorbing carbon monoxide in sulfuric acid by a metal compound, wherein the dosage of the sulfuric acid is 10-60 ml/mol of formaldehyde, the pressure of the carbon monoxide is 0.1-4.0 MPa, the dosage of the metal compound is 0.005-0.3 mol/mol of formaldehyde, the reaction temperature is 0-50 ℃, and the reaction time is 10-60 minutes.

The metal compound of the invention is cuprous sulfate, cupric oxide, cuprous oxide, copper powder, silver sulfate or a mixture thereof.

The temperature of the coupling reaction is preferably controlled to be 80-130 ℃, in order to make methyl formate also serve as a solvent, the molar ratio of the reactant formaldehyde/formic acid is preferably 0.3-0.9, and the reaction time is preferably 3-9 hours.

The reaction of the methanolysis coupling reaction solution can be carried out in an open reflux device or a closed reaction kettle.

The formaldehyde includes trioxymethylene and paraformaldehyde.

The final reaction pressure for synthesizing methyl glycolate by methyl formate and formaldehyde is 4.0-7.0 MPa.

In the present invention, methyl formate and formaldehyde are subjected to the following two reactions. The total reaction is as follows:

there is also by-product Methyl Methoxyacetate (MMA). After the reaction of methyl formate with formaldehyde, the methanol is decomposed again to obtain 50 to 75% Methyl Glycolate (MG).

Comparedwith the prior art, the invention has the advantages of mild process conditions; the yield of reaction products is high, 50-75% of methyl glycolate can be obtained, and the sum of MG and MMA can reach 70-94% (the total yield in the prior art is only about 50%); the reaction conditions are mild, the reaction temperature is 60-180 ℃, the initial reaction pressure is normal pressure, and the final reaction pressure is 4.0-7.0 MPa (in the prior art, the reaction pressure is 15-30 MPa, and the temperature is 140-180 ℃).

The following are examples of the present invention.

Example 1:

equimolar copper oxide (1.2 g) and copper powder (0.97 g) were mixed and added to a corrosion resistant reactor containing 20ml sulphuric acid, carbon monoxide 2.0MPa was added and the temperature was maintained at 31 ℃ for 20 minutes to initially form H₂SO₄/Cu(CO)_n ⁺(ii) a After carbon monoxide is vented, 8 g of trioxymethylene and 45ml of methyl formate are added, and the mixture reacts for 4 hours at the constant temperature of 110 ℃; then, 25ml of the coupling reaction mixture was decomposed with 50ml of methanol at a constant temperature of 100 ℃ for 2 hours, and the yields before and after the decomposition with methanol were shown in Table 1.

TABLE 1

Experiments	YMG(％)	YMMA(％)	YMG+MMA(％)
				Before methanol decomposition	39.17	22.48	61.65
After the methanol is decomposed	56.16	31.01	87.17

Example 2:

silver sulfate (4.68 g) was added to a corrosion-resistant reaction vessel containing 15ml of sulfuric acid, carbon monoxide was added at 1.0MPa, and the temperature was maintained at 50 ℃ for 40 minutes to first form H₂SO₄/Ag(CO)_n ⁺(ii) a After carbon monoxide is vented, 10 g of trioxymethylene and 60ml of methyl formate are added, and the mixture reacts for 2 hours at the constant temperature of 150 ℃; then, the reaction mixture was reacted at 120 ℃ for 1 hour, and 15ml of the coupling reaction mixture was decomposed with 45ml of methanol, and the yields before and after the decomposition with methanol were shown in Table 2.

TABLE 2

Experiments	YMG(％)	YMMA(％)	YMG+MMA(％)
				Before methanol decomposition	51.74	28.80	80.54
After the methanol is decomposed	59.82	34.39	94.21

Example 3:

silver sulfate (3.12 g) was charged into a corrosion-resistant reaction vessel containing 10ml of sulfuric acid, carbon monoxide was added at 3.0MPa, the temperature was maintained at 20 ℃ for 50 minutes, carbon monoxide was vented, 24 g of trioxymethylene and 45mlof methyl formate were added, the reaction was carried out at 110 ℃ for 6 hours, the reaction was carried out at 80 ℃ for 2 hours, 10ml of the coupling reaction solution was decomposed with 30ml of methanol, and the yields before and after the decomposition of methanol were as shown in Table 3.

TABLE 3

Experiments	YMG(％)	YMMA(％)	YMG+MMA(％)
				Before methanol decomposition	36.70	25.21	61.91
After the methanol is decomposed	50.47	28.36	78.83

Example 4:

referring to example 3, 6.24 g of silver sulfate was charged into a reaction vessel containing 60ml of sulfuric acid, and after carbonylation, 15 g of trioxymethylene and 50ml of methyl formate were added to react at 75 ℃ for 9 hours, and then 20ml of the reaction solution was decomposed with 20ml of methanol, and the results are shown in Table 4.

TABLE 4

Experiments	YMG(％)	YMMA(％)	YMG+MMA(％)
				Before methanol decomposition	24.43	18.75	44.18
After the methanol is decomposed	42.39	24.32	67.71

Example 5:

changing 'copper oxide and copper powder' into cuprous oxide (1.74 g), 15ml of sulfuric acid dosage, 12 g of trioxymethylene and 50ml of methyl ester, and reacting for 3 hours at 100 ℃; the same procedure as in example 1 was repeated, and the reaction results are shown in Table 5.

TABLE 5

Experiments	YMG(％)	YMMA(％)	YMG+MMA(％)
				Before methanol decomposition	41.38	22.63	64.01
After the methanol is decomposed	55.47	30.68	86.15

Claims (6)

1. A synthetic method of methyl glycolate and a catalyst thereof are characterized in that methyl formate and formaldehyde are used as raw materials, a sulfuric acid/metal carbonyl compound is used as a catalyst, a coupling reaction liquid is obtained by coupling reaction for 1-12 hours at 60-180 ℃, methanol is added to carry out decomposition reaction for 1-2 hours at 60-130 ℃, and methyl glycolate is obtained, wherein the molar ratio of formaldehyde to methyl formate is 0.1-2, the amount of sulfuric acid/metal carbonyl compound is 5-85 g/mol of formaldehyde, and the amount of methanol is 0.5-3 times (volume) of the coupling reaction liquid.

2. The method and catalyst according to claim 1, wherein the sulfuric acid/metal carbonyl compound is prepared by absorbing carbon monoxide in sulfuric acid with 10-60 ml/mol of sulfuric acid, 0.1-4.0 MPa of carbon monoxide pressure, 0.005-0.3 mol/mol of formaldehyde, 0-50 ℃ of reaction temperature, and 10-60 minutes of reaction time.

3. The method and catalyst of claim 2 wherein the metal compound is selected from the group consisting of cuprous sulfate, cupric oxide, cuprous oxide, copper powder, silver sulfate, and mixtures thereof.

4. The method and catalyst as claimed in claims 1 and 2, wherein the formaldehyde comprises trioxymethylene and paraformaldehyde.

5. The synthesis method and catalyst according to claims 1 and 2, characterized in that the reaction of the methanolysis coupling reaction solution can be carried out in an open reflux device or a closed reaction kettle.

6. The synthesis method and catalyst according to claim 1 and 2, characterized in that the temperature of the coupling reaction is preferably 80-130 ℃, the reaction time is preferably 3-9 hours, and the molar ratio of formaldehyde/formaldehyde formate (mol ratio) is preferably 0.3-0.9.