JPS603304B2 - 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. Maleic anhydride Dichlorosuccinic anhydride Monochloromaleic anhydride Trichlorosuccinic anhydride Dichloromaleic anhydride Conventionally, anhydrous ferric chloride or anhydrous aluminum chloride has been used as a catalyst in the above reaction, but these catalysts The yield of maleic acid is low and the reaction takes a long time.

It is also known to use barium chloride to promote dehydrochlorination, but barium chloride has the drawback of being a negative catalyst for the reaction. For this reason, a new method for producing dichloromaleic acid using ferric chloride hexahydrate as a catalyst (Tokukan Sho 49-124021) furthermore introduced anhydrous ferric chloride hexahydrate as a catalyst.
A method has been proposed in which iron is used and water is added during the chlorination reaction (Tokukan Sho 50-52022). However,
If you follow the above method, you can expect to improve the yield of dichloromaleic anhydride and shorten the reaction time, but in the case of the former method, free water and in the latter method, the added water is Because it coexists with chlorine gas, which is a reaction raw material, and hydrogen chloride gas, which is a reaction by-product, when carrying out the reaction on an industrial scale, it can cause very serious problems in terms of the cost of reactor equipment and corrosion. Hard to avoid. The inventors of the present invention have conducted intensive research into a method for obtaining dichloromaleic anhydride in a short time and in high yield without such drawbacks, and have found that if fumaric acid is present even in the absence of water or a water source. He discovered that it would be possible to improve the yield of dichloromaleic anhydride and shorten the reaction time, as well as solve the problem of corrosion of the equipment, and filed an application earlier (Tokuiso Sho 51-97624 (Samurai Seki Sho 53-2).
3923)).

However, as a result of further research, it was discovered that dicarboxylic acids other than fumaric acid have the same effect as fumaric acid, and the present invention was completed.

That is, the gist of the present invention is that in the presence of anhydrous ferric chloride and a dicarboxylic acid (excluding fumaric acid),
The present invention relates to a method for producing dichloromaleic anhydride, which comprises reacting maleic anhydride with chlorine gas.

To explain the present invention in more detail, normal maleic anhydride and chlorine gas are used as raw materials, but in order to prevent corrosion of equipment materials and achieve the effects of the present invention, these raw materials must be It is preferable to supply it in an anhydrous state.

The higher the reaction, the richer it is. Hydrochloric acid gas generated is removed and the reaction rate becomes faster, which is preferable. However, if the temperature is too high, the raw material maleic anhydride or the reaction intermediate monochrome maleic anhydride sublimates and the yield decreases, so the reaction rate is usually 100 to 200. ℃
, preferably 120-180 pm, optimally 130-1 pm
Selected from a range of 7030. Particularly when it is carried out industrially, the first stage reaction of the above reaction mechanism, that is, the reaction to produce dichlorosuccinic anhydride, is 130 to 160%, and the reaction of dehydrochlorination and general precipitation of dichlorosuccinic anhydride is 150% to 150%.
Preferably, the reaction temperature is selected such that it is carried out at ~170<0>C. Theoretically, 2 moles of chlorine gas are consumed based on maleic anhydride.

Although the amount of chlorine gas blown cannot be determined unconditionally since the chlorine utilization rate varies depending on the blown speed and the state of condensation, it is usually sufficient if it is about 2.2 to 4.0 times the molar amount of maleic anhydride. As for the blowing rate of chlorine gas, the blowing rate used in the usual chlorination reaction of maleic anhydride is adopted. The reaction time varies depending on the reaction temperature, chlorine blowing rate, blowing type, Seizusa type, and Takayo speed, but it is usually 3 to 2 hours.It is necessary to use anhydrous ferric chloride as the catalyst. As mentioned above, hydrated salts cause problems such as corrosion of the material and must be avoided.

The amount used is usually 1 to 1 to maleic anhydride.
It is 5% by weight. Therefore, it is necessary to have a dicarboxylic acid (excluding fumaric acid) present during the reaction of the method of the present invention. Examples of dicarboxylic acids that can be applied to the present invention include maleic acid, dichloromaleic acid, monochloromaleic acid, succinic acid, glutaric acid, adipic acid, and phthalic acid. preferable. The dicarboxylic acid present according to the process of the invention is usually used in an amount of 1 to 15% by weight, based on maleic anhydride, preferably 3 to 1% by weight.

The form of the reaction is not particularly limited, and the reaction is usually carried out in a batch manner without a solvent, and a glass-lined glass-lined reactor with a rope casing is usually used as the reactor.

For example, several such reactors are arranged in parallel, chlorine gas is introduced from one direction, unreacted chlorine gas is absorbed into the next reaction tank, and chlorine gas is introduced after the reaction in the reaction tank to which chlorine gas was first introduced is completed. It is preferable to perform the reactions alternately with the directions reversed, as this 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. To obtain dichloromaleic anhydride from the reaction product obtained in this way, ordinary organic chemical methods such as distillation under reduced pressure or normal pressure, and recrystallization using benzene, toluene, chloroform/carbon tetrachloride, etc. are adopted. be done.

The method of the present invention has been explained in detail above, but if the method of the present invention is followed, there will be no problem such as corrosion of the material of the reactor.
Since dichloromaleic anhydride can be produced in high yield and in a short time, it is extremely advantageous in industrial scale implementation.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 300 tons of maleic anhydride, 6 tons of anhydrous ferric chloride, and 15 tons of maleic acid were heated and melted at 160 qo.

Add 16,000 chlorine gas to this solution and add 70 tons of dehydrated chlorine gas.
The chlorination reaction was carried out by blowing at a rate of hr. After 1 calm hour, the blowing of chlorine gas was stopped, and the mixture was heated under reflux for 1 hour to complete the dehydrochloric acid reaction, and then the reaction product liquid was distilled. b. p.
Fractions from 193 to 1970 were obtained.

The yield was 478 kg, and as a result of gas chromatography analysis, the composition of this crab was 98% dichloromaleic anhydride,
The monochloromaleic anhydride was 1.5%, the tetrachlorosuccinic anhydride was 0.5%, and the yield was 92%. Comparative Example 1 The reaction and distillation were carried out in the same manner as in Example 1 without adding maleic acid, and as a result, a fraction of 465 mm was obtained.

The composition of this fraction was 22% dichloromaleic anhydride, 38% monochloromaleic anhydride, and 40% tetrachlorosuccinic anhydride, and the yield was 20%. Comparative Example 2 The reaction and distillation were carried out in the same manner as in Comparative Example 1, except that dehydrated chlorine gas was blown in at a rate of 15 tahr for 5 q of life.
A fraction of 473 min was obtained.

The composition of this fraction is 93% dichloromaleic anhydride, 2% monochloromaleic anhydride, 5% tetrachlorosuccinic anhydride.
%, and the yield was 86%. Example 2 The reaction and distillation were carried out in the same manner as in Example 1, except that 15 minutes of succinic acid was added in place of 15 minutes of maleic acid.

As a result, 473 pieces of crab with a boiling point of 193-1970 was obtained.
The composition of this crab material was 97% dichloromaleic anhydride, 2% monochloromaleic anhydride, and 1% tetrachlorosuccinic anhydride, and the yield was 90%. Example 3 The reaction and distillation were carried out in the same manner as in Example 1, except that 15% of maleic acid was replaced with 20% of monochloromaleic acid.

Claims (1)

[Claims] 1. A method for producing dichloromaleic anhydride, which comprises reacting maleic anhydride with chlorine gas in the presence of anhydrous ferric chloride and a dicarboxylic acid (excluding fumaric acid).