JP3886198B2 - Method for producing chlorinated acetone - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process for producing chlorinated acetones useful as an intermediate for medicines and agricultural chemicals.
[0002]
[Prior art]
Known methods for producing chlorinated acetones include a method of chlorinating acetone with chlorine using light, a metal chloride, an acid, a metal organic acid salt, etc. as a catalyst, and a method by oxidation of a corresponding chlorinated alcohol. .
[0003]
It is also known that acetoacetic acid and acetoacetic acid ester can be decomposed using an acid or basic substance as a catalyst, and acetone can be obtained in any case.
[0004]
[Problems to be solved by the invention]
It is known that chlorinated acetone can be obtained by heating chlorinated acetoacetate in the presence of aqueous hydrochloric acid (Annales de Chimie et de Physique [6] 24, 82). However, unlike acetoacetate which is easily hydrolyzed with acid or base as a catalyst to produce acetone, chlorinated acetoacetate cannot be easily hydrolyzed with aqueous hydrochloric acid. The reaction is carried out in a sealed tube at ˜170 ° C.
[0005]
In this method, since the reaction temperature is high and water is used as a reactant, the reaction must be performed under high pressure. Therefore, the present invention provides a method for obtaining chlorinated acetone from chlorinated acetoacetate under milder conditions.
[0006]
[Specific means for solving the problem]
The inventors of the present invention have made extensive studies on a method for producing a corresponding chlorinated acetone from a chlorinated acetoacetate. As a result, the chlorinated acetoacetate and hydrogen chloride can be efficiently heated by heating them in the presence of a novel catalyst. The inventors have found that chlorinated acetone can be obtained, and have completed the present invention.
[0007]
That is, the present invention relates to the general formula (1),
_{CH n Cl 3-n COCH m} Cl 2-m CO 2 R (1)
(In the formula, R represents an alkyl group or a chloroalkyl group which may have a C _{1 to} C ₅ branch. N and m represent 0 or a positive integer, and 0 ≦ n ≦ 3, 0 ≦ m ≦. 2 except where n = 3 and m = 2 , and n or m may be 0 in either or both). In contact with hydrogen, general formula (2),
_{CH n Cl 3-n COCH m} + 1 Cl 2-m (2)
In the method for producing chlorinated acetone represented by the formula (wherein n and m are the same as described above), this is a method for producing chlorinated acetone using triphenylphosphine as a catalyst.
[0008]
In the chlorinated acetoacetate ester of the general formula (1) according to the present invention, R in the formula is an alkyl group or chloroalkyl group which may have a C _{1 to} C ₅ branch, and has a large number of carbon atoms. There are no advantages in using the compounds, specifically, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, tert-butyl group, and the like. Examples in which an arbitrary number of hydrogen atoms are substituted with chlorine atoms, for example, a dichloroethyl group, a trichloroethyl group, a tetrachloroethyl group and the like can be mentioned. Specific examples of the chlorinated acetoacetate of the general formula (1) include ethyl 2-chloroacetoacetate, methyl 2-chloroacetoacetate, ethyl 2,2-dichloroacetoacetate, methyl 2,2-dichloroacetoacetate, 4 -Ethyl chloroacetoacetate, methyl 4-chloroacetoacetate, ethyl 4,4-dichloroacetoacetate, methyl 4,4-dichloroacetoacetate, ethyl 2,2,4-trichloroacetoacetate, methyl 2,2,4-trichloroacetoacetate Ethyl 4,4,4-trichloroacetoacetate, methyl 4,4,4-trichloroacetoacetate, ethyl 2,2,4,4-tetrachloroacetoacetate, methyl 2,2,4,4-tetrachloroacetoacetate , Ethyl pentachloroacetoacetate, methyl pentachloroacetoacetate and the like are preferably used.
[0009]
The reaction according to the method of the present invention is represented by the following reaction formula (3),
_{CH n Cl 3-n COCH m} Cl 2-m CO 2 R + HCl → CH n Cl 3-n COCH m + 1 Cl 2-m + CO 2 + RCl (3)
(Wherein R 1 , n and m are the same as above).
[0010]
The present invention is performed by heating chlorinated acetoacetate added with triphenylphosphine as a catalyst and discharging by-product carbon dioxide gas and chlorinated alkane out of the system while introducing hydrogen chloride gas therein. Is preferred. The amount of the catalyst used is 0.001 to 0.1 mol, preferably 0.02 to 0.05 mol, per 1 mol of chlorinated acetoacetate. There is no technical problem even if 0.1 mol or more is used. The hydrogen chloride gas is used in an amount of 1 mole or more, usually 1 to 10 moles per mole of chlorinated acetoacetate. Since the reaction is a reaction between a liquid and a gas, a known device that promotes mutual contact, such as a stirrer or a sparger, may be used. Hydrogen chloride may be used with a gas inert to the reaction, such as nitrogen, argon, etc. to facilitate control of the reaction. Although the reaction varies depending on the type of chlorinated acetoacetate, it is preferably carried out at 50 to 200 ° C., preferably at 80 to 150 ° C., and more preferably at about 100 to 130 ° C. because the reaction is easily controlled. If it is less than 50 degreeC, reaction does not occur substantially, and exceeding 200 degreeC may decompose | disassemble a product, and is unpreferable. Further, this reaction is carried out at about 1 to 10 kg / cm ² , but there is no advantage in carrying out under pressure in particular, and it is usually carried out under almost atmospheric pressure. The chlorinated acetone containing the by-product obtained by the method of the present invention is purified by a conventional method such as water washing, basic aqueous solution washing and distillation after the reaction. The apparatus used in the method of the present invention is preferably an apparatus made of a material such as stainless steel, a heat-resistant nickel alloy, a fluororesin, or glass, or an apparatus made of a material lined with these materials.
[0011]
The method of the present invention can also be carried out in the presence of a solvent. As the solvent, a solvent which is inert to chlorination such as a chlorinated solvent or a fluorinated solvent and has a sufficiently high boiling point as compared with the chlorinated acetoacetate of the raw material or the chlorinated acetone of the product is preferable. For example, carbon tetrachloride, ethane tetrachloride, 1,1-dichloro-1-fluoroethane, 1,1,1-trifluoro-2,2-dichloroethane, 1,1,1,2,2-pentafluoro-3 , 3-dichloropropane, 1,1,2,2,3-pentafluoro-1,3-dichloropropane, 2,4-dichlorotrifluorotoluene, 1,4-bistrifluoromethylbenzene, hexachloroacetone, etc. Can do.
[0012]
The method for obtaining the chlorinated acetoacetate used in the method of the present invention is not particularly limited, and examples thereof include a method of chlorinating acetoacetate with chlorine in the presence or absence of a catalyst. Instead of acetoacetate, chlorinated acetoacetate which has already been partially chlorinated can be used. Examples of the catalyst include quinoline, triphenylphosphine, morpholine and ferric chloride, and quinoline, triphenylphosphine and the like are particularly preferable. These catalysts are used in an amount of 0.001 to 0.1 mol, preferably 0.03 to 0.06 mol, per mol of acetoacetate. Chlorine gas is used in an amount of about 5 to 10 moles per mole of acetoacetic acid ester, but sufficiently good results can be obtained even by about 5 to 7 moles by adjusting the reaction.
[0013]
This chlorination reaction may be performed in the presence of a catalyst from the beginning, but it is a sequential reaction, and the reaction proceeds to a dichloro compound at a relatively low temperature without a catalyst. Further, it is preferable to use a highly chlorinated chlorinated acetoacetate, and this method will be described below. Since the chlorination reaction is an exothermic reaction, the temperature at which chlorine gas is blown in the reaction may be arbitrary, and the temperature of the reaction solution rises as soon as it is blown. In order to complete the entire reaction smoothly, air is blown from room temperature (20-30 ° C.), and the temperature rise of the reaction solution due to heat generated by the reaction is reduced by chlorine supply, dilution with an inert gas such as nitrogen, or cooling using an apparatus. The reaction is controlled so as to maintain a temperature of about 30 to 60 ° C. by heating. The exotherm decreases when about 2 mol of chlorine gas is consumed per 1 mol of acetoacetate.
[0014]
Further, in order to increase the degree of chlorination, for example, pentachloroacetoacetate, the reaction temperature may be increased, but the reaction is continued by adding the above catalyst. Since heat is further generated by adding a catalyst, the reaction is completed by maintaining the temperature at 60 to 100 ° C., preferably 70 to 90 ° C., to obtain pentachloroacetoacetate. If the reaction is too intense, it may be cooled from the outside, and if the reaction is slow, it may be heated.
[0015]
After completion of the chlorination reaction, the reaction product may be washed with a basic aqueous solution and / or water, then dried and purified by an operation such as distillation. A crude chlorinated acetoacetate purged with unreacted chlorine and hydrogen chloride formed by gas blowing is sufficient. When a solvent is used, it is preferably removed by distillation or the like.
[0016]
As other methods, chloroacetoacetate can be produced by a method of reacting acetoacetate with chlorine by photocatalyst irradiation, a method of reacting acetoacetate with sulfuryl chloride by heating, or the like.
[0017]
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these embodiments.
[0018]
【Example】
[Preparation of pentachloroacetoacetate]
Methyl acetoacetate (1.16 kg) was placed in a glass reactor equipped with a gas blowing tube and a reflux condenser, and chlorine gas was gradually blown at room temperature. The temperature in the reactor rose to reach about 60 ° C. Then, it heated up gently and raised to 65 degreeC and continued reaction. When about 1.42 kg of chlorine gas was consumed, the exotherm decreased, so when triphenylphosphine (47 g) was added, the exotherm was generated again, but the reaction was continued by heating to 90 ° C. While tracing the composition in the reactor by gas chromatography, the reaction was completed until methylpentachloroacetoacetate reached the maximum concentration. The amount of chlorine gas introduced was about 4.0 kg. Thereafter, nitrogen gas was blown into the reactor to drive off unreacted chlorine and generated hydrogen chloride. The crude methyl pentachloroacetoacetate in the reactor was 2.81 kg, and the selectivity for methyl pentachloroacetoacetate was 71% (area%, the same applies hereinafter).
[0019]
〔Example〕
Triphenylphosphine (78 g) was added to the obtained crude pentachloroacetoacetic acid methyl ester and heated to 100 to 130 ° C., and reacted while continuously introducing hydrogen chloride gas. After completion of the reaction, the organic matter remaining in the reactor was 2.38 kg. According to gas chromatographic analysis, tetrachloroacetone 4.5%, pentachloroacetone 72.1%, hexachloroacetone 18.7%, pentachloroacetoacetate Methyl was 4.7%. This was distilled under reduced pressure to obtain 1.34 kg of pentachloroacetone having a purity of 96%.
[0020]
[Reference example: Manufacturing example based on conventional technology]
Acetone (800 g) and quinoline (3.2 g) as a catalyst were placed in a glass reactor equipped with a gas blowing tube, and 4.4 kg of chlorine gas was gradually blown at room temperature. The temperature in the reactor rose and reached about 60 ° C. Then, it heated gently and raised to 100 degreeC and continued reaction. While monitoring the composition in the reactor with a gas chromatograph, when the amount of pentachloroacetone reached the maximum in the reaction solution, the chlorine gas was stopped, unreacted chlorine, and generated hydrogen chloride were driven out by blowing nitrogen gas. The remaining reaction solution was 2.97 kg, 25% trichloroacetone, 5% tetrachloroacetone, 58% pentachloroacetone, and 12% hexachloroacetone. This was purified by precision distillation to obtain 909 g of pentachloroacetone having a purity of 95%.
[0021]
【The invention's effect】
According to the method of the present invention, there is an effect that chlorinated acetoacetate can be converted to chlorinated acetone at a relatively low temperature.

Claims (3)

Formula (1),
_{CH n Cl 3-n COCH m} Cl 2-m CO 2 R (1)
(In the formula, R represents an alkyl group or a chloroalkyl group which may have a C _{1 to} C ₅ branch. N and m represent 0 or a positive integer, and 0 ≦ n ≦ 3, 0 ≦ m ≦. 2 except where n = 3 and m = 2 , and n or m may be 0 in either or both). General formula (2) in contact with hydrogen,
_{CH n Cl 3-n COCH m} + 1 Cl 2-m (2)
(In the formula, n and m are the same as described above.) A method for producing chlorinated acetone, wherein triphenylphosphine is used as a catalyst.   The method for producing chlorinated acetone according to claim 1, wherein the chlorinated acetoacetate is pentachloroacetoacetate and the chlorinated acetone is pentachloroacetone.  The method for producing chlorinated acetone according to claim 1 or 2, wherein 0.001 to 0.1 mol of triphenylphosphine is used per 1 mol of chlorinated acetoacetate.