CN101318901A - A new synthesis process of dimethyl fumarate - Google Patents

Abstract

The invention relates to a new process for synthesizing preservative dimethyl fumarate. Fumaric acid and methanol undergo two-stage esterification under the action of a catalyst to generate the dimethyl fumarate. Wherein, the catalyzer is cerous methanesulfonate, and the application of the new process and the catalyzer overcomes the deficiencies existing in the existing process, and can effectively reduce the production cost; and the aftertreatment is simple, has little environmental pollution, and has good Development and application prospects.

Description

A new synthesis process of dimethyl fumarate

technical field

The invention belongs to the technical field of synthesis of ester compounds in organic chemistry, in particular to a synthesis method of dimethyl fumarate.

Background technique

Dimethyl fumarate (Dimethyl fumarate), referred to as DMF, is a new type of preservative developed vigorously at home and abroad. It has significant characteristics such as high efficiency, broad-spectrum antibacterial, low toxicity, and low price. It has special effects on molds, especially aflatoxins. Inhibitory effect, and low inhibitory concentration, also known as mold killer. DMF is sublimable, so it also has dual functions of contact sterilization and fumigation sterilization, which are difficult for general preservatives. Since DMF quickly changes into the normal metabolite fumaric acid after entering the human body, it is safe to use and is widely used in food, grain, feed, etc., as well as preservation of vegetables and fruits. It is more and more used in the food industry. more and more widely. Due to the small amount of use and low cost when achieving the target effect, compared with similar products, its market capacity is larger and its development prospect is broader, so it is worthy of vigorous application and development.

There are two main processes for synthesizing DMF: one is to use maleic anhydride as a raw material to generate dimethyl maleate under the action of an esterification catalyst, and then obtain dimethyl fumarate through isomerization; the other is to use Fumaric acid is used as a raw material, and dimethyl fumarate is directly prepared through esterification reaction with methanol under the action of a catalyst.

At present, the second process route, namely the direct esterification method, is often used at home and abroad to synthesize, and the catalysts used are mostly protonic acids such as sulfuric acid. This process has the following disadvantages:

1. Long production lines and high production costs

Protonic acid catalysts such as sulfuric acid severely corrode the equipment, which increases equipment investment; subsequent removal of the catalyst requires neutralization and water washing processes, and the production line is long; under the action of sulfuric acid, the selectivity of the reaction is poor, there are many side reactions, and the product yield and purity of the product Low, high production costs; at the same time, the discharge of a large amount of acid water will also pollute the environment.

2. The amount of methanol used is large and the reaction time is long

Because methanol has a low boiling point and is miscible with water, no matter what kind of water-carrying agent is used, methanol will be lost. Therefore, water cannot be separated during the reaction process. The way to improve the yield is usually an excess of methanol. However, the influence of excess methanol on the yield was not significant. At the same time, excess methanol needs to be recovered, which increases the burden of post-processing.

In addition, in the prior art, catalysts can also be solid acids, ion exchange resins, heteropolyacids, inorganic salts, etc. Although using these materials as catalysts can overcome the above-mentioned problems to a certain extent, there are difficulties in the preparation of catalysts. , high dosage, large alkyd molar ratio, poor catalyst reusability and other shortcomings, so it is necessary to propose a new process and improve the previous method.

Contents of the invention

The purpose of this invention is to provide a kind of production technology of improved dimethyl fumarate for overcoming above-mentioned deficiencies in the prior art, the catalyst consumption of this technology is few, reaction yield height, the product purity that synthesizes is high, catalyst Reusable, low production cost, less environmental pollution.

In order to solve the above technical problems, the present invention takes the following technical solutions:

A new process for the synthesis of dimethyl fumarate, fumaric acid and methanol undergo an esterification reaction under the action of a catalyst to generate the dimethyl fumarate, characterized in that: the catalyst is methylsulfonate Cerous acid.

A new process for the synthesis of dimethyl fumarate according to claim 1, characterized in that: the addition of the catalyst cerous methanesulfonate is 0.3-0.4% of the total mass of fumaric acid and methanol .

A new process for synthesizing dimethyl fumarate according to claim 1, characterized in that: the esterification reaction is carried out at reflux temperature, and the reaction time is 7 to 10 hours.

a kind of synthetic new technique of dimethyl fumarate according to claim 1, is characterized in that: when carrying out esterification reaction, described methyl alcohol is excessive relative to fumaric acid.

A new process for synthesizing dimethyl fumarate according to claim 4, characterized in that: the substance ratio of the methanol to the fumaric acid is 6.0-8.0:1.

According to the new synthetic process of a kind of dimethyl fumarate described in any one of the above claims, it is characterized in that: the reaction is carried out in two stages, in the first stage, half of the amount of methanol is dropped into, after the reaction is complete, steam Methanol and water are removed, and then the remaining methanol is put into the reaction for the second stage. Owing to adopting above technical scheme, the present invention has following advantage and positive effect compared with prior art:

1. Using cerous methanesulfonate as a catalyst, compared with the existing acidic catalyst, the reaction speed is close; but the amount of catalyst is less, the selectivity is good, and the catalyst can be reused after simple separation, which reduces the cost of raw materials.

2. Compared with the existing acidic catalysts, cerous methanesulfonate will not corrode equipment, saving equipment investment; removing the catalyst requires simple filtration without neutralization, water washing and other processes, reducing sewage discharge and being environmentally friendly .

.3. Compared with the existing process route, although the amount of methanol is not reduced and the reaction time is not shortened, the yield of the product is improved.

Detailed ways

Add 116.0g (1.0mol) fumaric acid, 96.12g (3.0mol) methanol, 1.24g (0.0025mol) cerous methanesulfonate in sequence to a 500mL three-necked reaction flask equipped with a reflux condenser, and heat to reflux for about 3 hours Afterwards, remove the water that methyl alcohol and reaction generate, then add 96.12g (3.0mol) methyl alcohol in the reaction flask and continue heating and reflux reaction 4h, filter while hot and reclaim cerous methanesulfonate (the cerous methanesulfonate that reclaims can reuse). The filtrate was washed with water, allowed to stand, cooled, crystallized, filtered with suction, and dried to obtain dimethyl fumarate in the form of white crystals. Product quality 137.95g (yield 95.8%), melting point 102～104 ℃.

The reaction equation is:

Wherein, above-mentioned cerous methanesulfonate can be synthesized by following method:

Weigh 14.4g of methanesulfonic acid, mix it with water at a volume ratio of 1:1 and add it to the flask, add 10.2g of cerium dioxide at one time, install a reflux condenser and fix it on an electromagnetic stirrer for heating, and slowly add it dropwise under reflux conditions 150mL of hydrogen peroxide, after reacting for 4-5h, filter while hot, wash the filter residue twice with a small amount of distilled water, combine the filtrate, evaporate to dryness, dry in a vacuum oven at 100°C for 3h, and put it in a desiccator for later use. The mass of the obtained cerous methanesulfonate was 23.2 g (the yield was 93.5%).

Claims (6)

1. new technology of synthesis of dimethyl fumarate, fumaric acid and methyl alcohol esterification take place under the effect of catalyzer generates described dimethyl fumarate, it is characterized in that: described catalyzer is the inferior cerium of methylsulphonic acid.

2. a kind of new technology of synthesis of dimethyl fumarate according to claim 1 is characterized in that: the add-on of the inferior cerium of described catalyzer methylsulphonic acid is 0.3～0.4% of fumaric acid and a methyl alcohol total mass.

3. a kind of new technology of synthesis of dimethyl fumarate according to claim 1 is characterized in that: described esterification is carried out under reflux temperature, and the reaction times is 7～10h.

4. a kind of new technology of synthesis of dimethyl fumarate according to claim 1 is characterized in that: when carrying out esterification, described methyl alcohol is excessive with respect to fumaric acid.

5. a kind of new technology of synthesis of dimethyl fumarate according to claim 4 is characterized in that: described methyl alcohol is 6.0～8.0: 1 with the amount of substance ratio of described fumaric acid.

6. according to the described a kind of new technology of synthesis of dimethyl fumarate of above-mentioned any claim, it is characterized in that: reaction divides two stages to carry out, fs, drop into the methyl alcohol of half amount earlier, after reacting completely, steam the first alcohol and water, drop into remaining methyl alcohol again, carry out the reaction of subordinate phase.