JPS6021155B2 - Method for producing dichloromaleic anhydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing dichloromaleic anhydride.

Dichloromaleic anhydride is a substance useful as a raw material for agricultural chemicals, medicines, etc., and is usually produced by directly reacting maleic anhydride and chlorine. However, the reaction mechanism is thought to consist of chlorination and dehydrochlorination reactions shown by the following formula. Ice-free maleic acid dichlorosuccinic anhydride monochloro ice-free maleic acid trichloro ice-free succinic acid dichloro-ice free maleic acid Anhydrous ferric chloride and anhydrous aluminum chloride have conventionally been used as catalysts for the above reaction; However, the yield of dichloromaleic anhydride is low, the reaction temperature is high, and the reaction takes a long time.

Therefore, as a method to compensate for this drawback, we proposed a method in which the reaction is carried out in the presence of anhydrous ferric chloride and a dicarboxylic acid.

The present inventors have conducted intensive studies on the above method in order to carry out the reaction in an industrially advantageous manner, and have found that during the reaction, the reaction rate of It was found that the reaction rate decreases with the passage of time, and at the same time, this decrease in the reaction rate causes the formation of tetrachlorosuccinic anhydride, which is an overreaction product.

Therefore, after further consideration based on the above knowledge, we found that
The present inventors have discovered that adding a dicarboxylic acid during the reaction can extremely effectively suppress the reduction in reaction rate and suppress the production of tetrachlorosuccinic anhydride, and have thus arrived at the present invention.

That is, the gist of the present invention is that when maleic anhydride is chlorinated in the presence of an anhydrous ferric chloride or anhydrous aluminum chloride catalyst to produce dichloromaleic anhydride, the remaining amount of maleic anhydride is 4 at the start of the reaction. The method of producing dichloromaleic anhydride is characterized in that the dicarboxylic acid is added after the weight % of the dicarboxylic acid reaches .

To explain the present invention in more detail, ordinary maleic anhydride and chlorine are used as raw materials.

The higher the reaction temperature, the more generated hydrochloric acid gas is removed and the reaction rate becomes faster; however, if the reaction temperature is too high, maleic anhydride as a raw material or monochloride as a reaction intermediate may be used. (b) Maleic anhydride, etc. sublimes, which not only reduces the yield, but also causes corrosion of the reactor material.
Selected from the range of 2000○, preferably 140 to 170
Selected from the range 00. Theoretically, 2 moles of chlorine are consumed based on maleic anhydride.

Although it cannot be generalized because the utilization rate of chlorine varies depending on the chlorine blowing rate or the frame loss condition, it is usually sufficient if the amount is about 2.5 to 3.0 times the molar amount of maleic anhydride. The reaction time varies depending on the reaction temperature, chlorine blowing rate, blowing type, chlorine blowing type, and Nada Azusa speed, but is usually 3~
2 Imitation temples are fine.

The amount of anhydrous ferric chloride or anhydrous aluminum chloride used as a catalyst is usually 0.3 to 15% by weight based on maleic anhydride.
, preferably 0.5 to 5% by weight.

Alternatively, a method such as adding iron powder instead of anhydrous ferric chloride to form anhydrous ferric chloride within the reaction system may be used.
The present invention is characterized in that the reaction is started with the above catalyst and the dicarboxylic acid is added during the reaction.

Examples of the dicarboxylic acid include fumaric acid, maleic acid, dichloromaleic acid, monochloromaleic acid, succinic acid, glutanic acid, adipic acid, phthalic acid, etc. Among these, dicarboxylic acids having 4 carbon atoms are preferred. The timing of addition of the dicarboxylic acid is preferably when the remaining amount of maleic anhydride is 4% by weight or less at the start of the reaction, and 15% by weight or less.
Particularly preferred is ~2% by weight.

Further, the amount of dicarboxylic acid added is selected from a range of about 1 to 2% by weight, preferably 2 to 15% by weight, based on the raw material maleic anhydride. The form of the reaction is not particularly limited, and the reaction is carried out according to conventional methods, and is usually carried out batchwise in the absence of a solvent.

For example, several glass-lined tank-type reactors with a flywheel are arranged in parallel, chlorine gas is introduced from one direction, and the chlorine gas is absorbed into the next reaction tank. After the reaction in the tank is completed, it is preferable to reverse the direction of introduction of chlorine gas and carry out the reactions alternately, as this further increases the utilization rate of chlorine. Furthermore, according to this method, it is also easy to recover hydrochloric acid gas, which is produced in large amounts as a by-product in this reaction. In the present invention, dichloromaleic anhydride can be industrially advantageously produced by an extremely simple operation of adding a small amount of dicarboxylic acid during the reaction.

The present invention will be explained in more detail by examples below.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

In the examples, "yield" refers to the yield based on the maleic anhydride charged.

Example 1 In a reaction tank, 294 g of maleic anhydride and 5 g of anhydrous ferric chloride were added.
Prepare for 9 days and heat to 16,000℃ to melt.

The reaction temperature was maintained at 160 oo, and the reaction solution was placed under a strong net offshore, and chlorine gas was blown into the reaction tank at a rate of 44 pm/hr. After about axis r,
When the concentration of maleic anhydride reached 5% by weight at the start of the reaction, the chlorination blowing rate was changed to 19 min/hr, 15 min/hr of fumaric acid was added, and the reaction was further carried out. When the reaction time was 1 hour in total, the blowing of chlorine was stopped and the reactant was distilled under normal pressure to obtain 475 g of dichloromaleic anhydride (purity 90% by weight, yield 92%). Example 2 The reaction and distillation were carried out in the same manner as in Example 1, except that 26% of dichloromaleic anhydride was added instead of fumaric acid, and 479% of dichloromaleic anhydride (purity: 9% by weight) was obtained.
, yield 92%).

Example 2 In a reaction tank, 294 g of maleic anhydride and 5 g of anhydrous ferric chloride were added.
Pour 9 tbsp and 4 tbsp of fumaric acid, heat to 16,000 ℃, and melt.

The reaction temperature was maintained at 160 °C, the reaction solution was forced to float under the ocean, and chlorine gas was blown into the reaction tank at a rate of 44 min/hr.

After about 30 minutes, the maleic anhydride concentration was 6% by weight at the start of the reaction.
At this point, the chlorine injection rate was changed to 19 min/hr, and 11 min/hr of maleic acid was added for further reaction. When the reaction time reached 1 liter in total, the injection of chlorine was stopped and the reactant was distilled under normal pressure, and dichloromaleic anhydride 4 was extracted.
77% (purity 96% by weight, yield 92%) was obtained. Example 4 In a reaction tank, 294 g of maleic anhydride and 5 g of anhydrous ferric chloride were added.
The mixture was heated and melted to 160q0.

The reaction temperature was maintained at 16,000 ℃, the reaction solution was heated under pressure, and chlorine gas was blown into the reaction tank at a rate of 100 pm/hr. Approximately
Thereafter, when the concentration of maleic anhydride reached 4% by weight at the start of the reaction, 29 g of fumaric acid was added and the reaction was further continued. Total reaction time is 8. After 3 hours, the chlorine injection was stopped and the reaction product was distilled under normal pressure to obtain 478 g of dichloromaleic anhydride (purity 95% by weight, yield 91%). Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that fumaric acid was not added.

After one hour, the reaction has not yet been completed, and the reaction intermediate, dichlorosuccinic anhydride, remains in the reaction solution as much as 6% by weight, and the overreaction product, tetrachlorosuccinic anhydride, remains at 6% by weight.
% by weight.

The reaction temperature was raised to 180 qo and chlorine gas was added for 19 q/min.
Although the blowing reaction was continued at a rate of 1.5 hr, dichlorosuccinic anhydride was reduced to only 31% by weight, and tetrachlorosuccinic anhydride was further increased to 14% by weight.

Example 5 In Example 1, instead of 5.99% of anhydrous ferric chloride,
When reaction and distillation were carried out under the same conditions as in Example 1 using 4.5 mm of anhydrous aluminum chloride, the yield of dichloromaleic anhydride was 474 mm (purity: 9% by weight, yield: 8%).
8%).

Comparative Example 2 In Example 5, the reaction was carried out under the same conditions as in Example 5 without adding fumaric acid during the reaction. One hour after the start of the reaction, the intermediate dichloroanhydride Amber production remains at 4% by weight, and
Tetrachlorosuccinic anhydride, an overreaction product, was produced in an amount of 5% by weight.

Claims (1)

[Claims] 1. When producing dichloromaleic anhydride by chlorinating maleic anhydride in the presence of anhydrous ferric chloride or anhydrous aluminum chloride catalyst, when the remaining amount of maleic anhydride reaches 40% by weight at the start of the reaction. A method for producing dichloromaleic anhydride, which comprises subsequently adding dicarboxylic acid.