JPS6052741B2 - Manufacturing method of hexachloroacetone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently obtaining highly pure hexachloroacetone when producing hexachloroacetone by reacting acetone with chlorine.

Hexachloroacetone is hydrolyzed under basic conditions to give trichloroacetic acid and chloroform, which can also be used in pharmaceuticals,
It is useful as an intermediate for agricultural chemicals, etc., and hexafluoroacetone can be produced by replacing chlorine with fluorine, making it an industrially important compound. Relatively many methods for synthesizing hexachloroacetone by chlorination of acetone are known. Book No. 2199934 (1940), H, C,
Cheng, Z.

Physlk, Chem, B2 roll, 308 pages (1934
However, these methods are not efficient as they require a long reaction time or a low yield of hexachloroacetone. U.S. Patent No. 3,265,740 (196) has been submitted as an improved method of these, but in this method, acetone and chlorine are reacted in the gas phase in a two-step initial process, and hydrogen chloride and acetone are reacted during the process. Although it is said to avoid by-products such as tantyl oxide and boron generated by the dehydration condensation reaction, it is not necessarily an advantageous method as the reaction time is long and heating is required from the beginning. Considering the relatively high temperature and the environmental impact of pyridine's bad odor, this method cannot be said to be preferable.

Furthermore, in the improved method described in JP-A-49-249, the reaction is carried out in three stages, in which the reaction is carried out at a low temperature in the initial stage where the degree of chlorination is low, and then the presence of an organic base such as pyridine J or its salt is carried out. The mixture is heated until it becomes an electride (3 to 4), and then reacted with chlorine under heating and light irradiation in the presence of the above-mentioned organic base or its salt.

According to this method, the reaction takes place in a relatively short time and at a low temperature.
However, there is a high possibility that side reactions will occur due to contact between hydrogen chloride and acetone in the liquid phase in the early process, and light irradiation in the later process has the disadvantages such as complicated equipment maintenance. This is not necessarily an industrially advantageous method. In view of the above-mentioned current state of the hexachloroacetone manufacturing method, the present inventors have conducted intensive studies to provide a more efficient method, and as a result, they have heated low chlorinated acetone in the presence of a catalytic amount of triphenylphosphine. However, by introducing chlorine and carrying out chlorination, it was discovered that highly pure hexachloroacetone can be obtained in high yield, and the present invention was thus achieved.

That is, in producing hexachloroacetone by the reaction of acetone and chlorine, the present invention introduces a mixed gas of chlorine and a small amount of nitrogen into acetone kept at 40°C or less,
An average of 2 to 2. ! The present invention relates to a method for producing hexachloroacetone, which is characterized by producing tetraminated acetone and then reacting it with chlorine while heating using triphenylphosphine as a catalyst.

The present invention will be explained in more detail.

In the initial process of chlorinating acetone, since this reaction is exothermic, the reaction solution is cooled and chlorine is introduced into acetone at a temperature of 5 to 40°C, preferably 10 to 30°C, together with a small amount of nitrogen. By introducing nitrogen at this time, the generated hydrogen chloride can be quickly removed from the reaction solution to the outside of the system, and side reactions such as dehydration condensation can be avoided.
If the amount of nitrogen introduced is too large, the amount of unreacted chlorine and organic matter accompanying the gas discharged to the outside of the system will increase, so the flow rate of nitrogen will be 11,100 to 1 chlorine by volume.
110 is appropriate. When the heat generation stops, the reaction is completed, and the reaction solution turns yellow, the introduction of chlorine is stopped, and nitrogen is introduced into the reaction solution to remove unreacted chlorine and hydrogen chloride in the system. Also at this stage, triphenylphosph. In can be added in catalytic amounts. In the next step, triphenylphosphine is added as a catalyst to acetone at 0.0%.
It is added in an amount of 1 to 5.0 mol%, preferably 0.2 to 2.0 mol%, and the reaction temperature is set at 70° C. or higher to stop the introduction of nitrogen and introduce only chlorine.

The reaction rate at this stage depends on the amount of triphenylphosphine added, and if triphenylphosphine is successively added when the reaction rate decreases, the reaction is quickly completed and highly pure hexachloroacetone is obtained. The reaction temperature during this period is suitably 70 to 160°C. In this reaction,
Average: 4.5~5'' Until chlorinated acetone is produced, chlorination proceeds relatively quickly even if the reaction temperature is kept at 70~120°C, so either reduce the amount of triphenylphosphine added or However, for further chlorination, increase the reaction temperature to 140°C or higher, adjust the amount of chlorine introduced, and add more triphenylphosphine if necessary to reduce the loss of chlorine. It can be set to a minimum of a. Almost the theoretical amount of chlorine introduced is sufficient, and the reaction time can be adjusted by adjusting the amount of catalyst added. A large input of triphenylphosphine is unnecessary both from an economic point of view and from the point of view of disposal of remaining catalyst residues. Triphenylphosphine may be added as a solid, but if it is dissolved in acetone or low chlorinated acetone, it can be added continuously using a pump. This reaction can also be carried out using the reaction product hexachloroacetone as a solvent. The produced crude hexachloroacetone can be easily separated from the catalyst used by simple distillation under reduced pressure.
Hexachloroacetone with 0% purity can be isolated. This reaction can be carried out by adding a distillation separation operation later.
Can be continuous or semi-continuous. When using a metal reactor, Fece3, NiCe2, and Sb that are considered to be mixed in
It is thought that C', Pce3, etc. react with triphenylphosphine to produce a dichloride, and are rather expected to have the effect of a catalyst aid, so there is no problem in adding a small amount of these.

On the other hand, water in the reaction system impairs the catalytic ability of triphenylphosphine, so moisture in the raw material acetone should be avoided as much as possible, and it is necessary to remove moisture to prevent corrosion of the equipment. If the water content is 25% or less, there is no problem with the catalytic effect.

Examples will be described below.

Example 1 Acetone 291y (5.0 mol) was placed in a cylindrical glass reactor equipped with a reflux condenser at the top with a coolant temperature of -10°C, and cooled with ice to bring the internal temperature to 0°C. , chlorine 2.5
A gas mixture of mol/h and 0.03 mol/h of nitrogen is introduced continuously.

The reaction occurs quickly and generates heat, so keep the internal temperature at 5-35℃.
After 42 hours, the reaction solution turned yellow due to unreacted chlorine, and the introduction of chlorine was stopped. At this time, an average of 2.1 chlorinated acetone was obtained based on gas chromatography and the amount of hydrogen chloride generated. After removing hydrogen chloride and chlorine from the reaction solution with nitrogen, the yield of low chlorinated acetone was 632y. With the reflux temperature set to water temperature and the cooling bath set to an oil bath, 1.25 mol% of triphenylphosphine was added to the above low chlorinated acetone 130.5y (1.0 mol), and when the reaction temperature was set to 70°C, chlorine was removed. The reaction was continued at 100-155°C by introducing at a rate of 0.5 mol/hour and gradually raising the reaction temperature as the chlorination reaction progressed.
．． P! 1! After a while, 260V of hexachloroacetone with a purity of 96.5% as determined by gas chromatography was obtained.

The overall yield was 91.6%. Comparative Example 1 Using 130.5y of the same low chlorinated acetone as in Example 1, 1.2y of pyridine
After adding 5 mol%, heat to 70°C and add 0.5 mol/chlorine.
Continue the introduction for a period of time and maintain the reaction temperature at 100-165°C.
After 7 hours of reaction, the purity was 7 by gas chromatography.
229 g of 1.5% hexachloroacetone was obtained.

Comparative Example 2 Pyridine 1.0 in the same low chlorinated acetone 1y as in Example 1
After adding y, the reaction temperature was kept at 70-110°C and chlorine was added at 0.4 mol/hour for 2. The purity of hexachloroacetone was 6.2% when the mixture was reacted for a while.

Thereafter, the reaction temperature was raised to 140° C., and the reaction was carried out at 0.33 mol/hour of chlorine for 3 hours while irradiating ultraviolet light using a 100 W high-pressure mercury lamp. 128% hexachloroacetone with a purity of 95.8% by gas chromatography
I got g. Example 2 Using 130.5 da of the same low chlorinated acetone as in Example 1,
When 0.2 mol% of triphenylphosphine is added, the reaction temperature is set at 70 to 140°C, chlorine is introduced at 0.5 mol/hour, and the reaction is allowed to proceed for 5 hours, the purity of hexagonal rare acetone is 1.
After that, the reaction temperature was raised to 155°C, 0.4 mol% of triphenylphosphine was successively added, chlorine was introduced at 0.5 mol/hour, and the reaction was carried out for 23 hours. 258 g of hexachloroacetone with a purity of .6% was obtained.

Simple distillation of this product yields 106~10TC/30TmHg.
Hexachloroacetone 245y, which was colorless and transparent and had a purity of 99.5%, was obtained. Example 3 Using the same reactor as in Example 1, acetone 116.
2y (2 moles), triphenylphosphine 0.
2 mol% of chlorine was added at a reaction temperature of 2 to 24°C.
．． The chlorination reaction was carried out by continuously introducing 5 mol/hour of nitrogen and 0.02 mol/hour of nitrogen into the acetone solution.

After stirring for 2 hours and 4 hours, when the reaction solution turned yellow due to unreacted chlorine, the introduction of chlorine and nitrogen was stopped.

At this time, 2.1 chlorinated acetone was obtained. This yellow coloration disappeared by raising the temperature of the reaction solution to 70 to 90°C, and a colorless and transparent solution was obtained. After that, 0.2 mol% of triphenylphosphine was further added, and the reaction temperature was adjusted to 90-160°C.
Introducing chlorine at a rate of 1.0 mol/hour while maintaining
After reacting for 8 hours, a pale yellow liquid was obtained, and crude hexachloroacetone 507y with a purity of 97.6% as determined by gas chromatography was obtained.

Claims (1)

[Scope of Claims] 1. A method for producing hexachloroacetone, which comprises reacting an average of 2 to 2.5 chlorinated acetone with chlorine while heating using triphenylphosphine as a catalyst. 2. To produce hexachloroacetone through the reaction of acetone and chlorine, a mixed gas of chlorine and a small amount of nitrogen is introduced into acetone kept below 40°C, and reacted to produce an average of 2 to 2.5 chlorinated acetones. and then reacting with chlorine while heating using triphenylphosphine as a catalyst.