Process for preparing monomethyl fumarate

Abstract

A process for preparing monomethyl fumarate from maleic acid anhydride as raw material includes such steps as alcoholizing by methanol at 30-70 deg.C for 1.5-5 hr while stirring, adding concentrated hydrochloric acid and isomerizing reaction at 30-80 deg.C for 20-60 hr (or adding ethyl acetate and then concentrated hydrochloric acid and isomerizing at 20-70 deg.C for 3-8 hr while stirring), centrifugal separation and vacuum drying. Its advantages include high output rate (95%), very low energy consumption and no environmental pollution.

Description

(1) Technical field

[0001] The invention relates to a preparation process of an antiseptic, in particular to a preparation process of monomethyl fumarate. (2) Technical background

[0002] At present, in the preservative industry, dimethyl fumarate (DMF) is widely used due to its excellent anti-mold effect, but DMF is severely irritating to the skin and eyes, and can cause skin allergies when it comes into contact with the human body, especially when used in large amounts The performance is more prominent in summer and autumn. Due to the use of concentrated sulfuric acid in the process, the depreciation of equipment is fast, and waste liquid is generated, which needs to be treated in an environmentally friendly manner. Therefore, people began to pay attention to a preservative with good effect and less irritation - monomethyl fumarate (MMF). MMF not only has the advantages of DMF, such as a wide range of PH applications, low toxicity, high efficiency, wide application, and ...

Examples

Embodiment 1

[0018] Embodiment 1: Maleic anhydride and methyl alcohol are dropped in the reaction tank by the ratio (weight ratio) of 98: 32, keep stirring with 45 rev / mins, and reaction system begins to drop in temperature, and this is because maleic anhydride is soluble in methanol Due to physical heat absorption. However, when part of the maleic anhydride dissolves, it will immediately undergo esterification reaction with methanol, and the temperature of the reaction system begins to rise. When the temperature rises to 50°C, cool the reaction tank with cooling water to keep the reaction temperature at 30--70°C. After 3 hours, it was cooled to room temperature to obtain monomethyl maleate.

Embodiment 2

[0019] Embodiment 2: the monomethyl maleate obtained by reaction is placed in the isomerization container, the concentrated hydrochloric acid of 0.5% of the monomethyl maleate weight is added, mix well, be placed in the container that can carry out air-cooling or water-cooling , keep the temperature of the whole isomerization reaction system at 60°C. After standing still for 50 hours, the monomethyl fumarate was taken out, and the powdery monomethyl fumarate product was obtained after crushing, with a yield of not less than 95%.

Embodiment 3

[0020] Embodiment 3: Solvent isomerization: place reaction gained monomethyl maleate in reaction pot, add ethyl acetate, the weight ratio of monomethyl maleate and ethyl acetate is 1: 3, then add maleic acid 1% concentrated hydrochloric acid of monomethyl ester weight, keep stirring at 50 rev / min, finish after 6 hours. During the isomerization process, cooling water is used to control the isomerization reaction temperature at about 50°C. Most of the monomethyl fumarate precipitates out in the form of precipitation, and it is centrifuged (3000 rpm) for 7 minutes to obtain monomethyl fumarate, which contains about 5-8% ethyl acetate, and placed at 50°C In the left and right ovens, the pure product of monomethyl fumarate was obtained after vacuum drying for 1 hour. This method is more complicated than the direct isomerization method. But because solvent exists in the isomerization process, the reaction temperature is easy to control, the product purity is higher, and the solvent...

(1) Technical field

[0001] The invention relates to a preparation process of an antiseptic, in particular to a preparation process of monomethyl fumarate. (2) Technical background

[0002] At present, in the preservative industry, dimethyl fumarate (DMF) is widely used due to its excellent anti-mold effect, but DMF is severely irritating to the skin and eyes, and can cause skin allergies when it comes into contact with the human body, especially when used in large amounts The performance is more prominent in summer and autumn. Due to the use of concentrated sulfuric acid in the process, the depreciation of equipment is fast, and waste liquid is generated, which needs to be treated in an environmentally friendly manner. Therefore, people began to pay attention to a preservative with good effect and less irritation - monomethyl fumarate (MMF). MMF not only has the advantages of DMF, such as a wide range of PH applications, low toxicity, high efficiency, wide application, and ...

Examples

Embodiment 1

[0018] Embodiment 1: Maleic anhydride and methyl alcohol are dropped in the reaction tank by the ratio (weight ratio) of 98: 32, keep stirring with 45 rev / mins, and reaction system begins to drop in temperature, and this is because maleic anhydride is soluble in methanol Due to physical heat absorption. However, when part of the maleic anhydride dissolves, it will immediately undergo esterification reaction with methanol, and the temperature of the reaction system begins to rise. When the temperature rises to 50°C, cool the reaction tank with cooling water to keep the reaction temperature at 30--70°C. After 3 hours, it was cooled to room temperature to obtain monomethyl maleate.

Embodiment 2

[0019] Embodiment 2: the monomethyl maleate obtained by reaction is placed in the isomerization container, the concentrated hydrochloric acid of 0.5% of the monomethyl maleate weight is added, mix well, be placed in the container that can carry out air-cooling or water-cooling , keep the temperature of the whole isomerization reaction system at 60°C. After standing still for 50 hours, the monomethyl fumarate was taken out, and the powdery monomethyl fumarate product was obtained after crushing, with a yield of not less than 95%.

Embodiment 3

[0020] Embodiment 3: Solvent isomerization: place reaction gained monomethyl maleate in reaction pot, add ethyl acetate, the weight ratio of monomethyl maleate and ethyl acetate is 1: 3, then add maleic acid 1% concentrated hydrochloric acid of monomethyl ester weight, keep stirring at 50 rev / min, finish after 6 hours. During the isomerization process, cooling water is used to control the isomerization reaction temperature at about 50°C. Most of the monomethyl fumarate precipitates out in the form of precipitation, and it is centrifuged (3000 rpm) for 7 minutes to obtain monomethyl fumarate, which contains about 5-8% ethyl acetate, and placed at 50°C In the left and right ovens, the pure product of monomethyl fumarate was obtained after vacuum drying for 1 hour. This method is more complicated than the direct isomerization method. But because solvent exists in the isomerization process, the reaction temperature is easy to control, the product purity is higher, and the solvent...

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