JPS63162646A - Production of monochloroacetone - Google Patents

Abstract

PURPOSE:To obtain the aimed compound in high purity in producing the titled compound from acetone and chlorine by reaction distillation method, by refluxing an organic solvent having a lower boiling point than acetone, inert to chlorine and hydrogen chloride, to the top of a column to suppress formation of mesityl oxide as a by-product. CONSTITUTION:In producing the titled compound useful as a raw material for dye, etc., by reaction between acetone and chlorine, a device equipped with a distillation column B, a condenser A and a reflux return piping D is used, an organic solvent having a lower boiling point than acetone, inert to chlorine and hydrogen chloride, is added to the device, the organic solvent is refluxed at the upper plate of the distillation column B, chlorine is continuously fed to the middle plate in the column B wherein acetone is refluxed and reacted with acetone. Further hydrogen chloride prepared as a by-product is removed out of the top of the column, the formed aimed compound is introduced in the bottom of the distillation column B while separating unreacted acetone by distillation, formation of by-products such as polychloroacetone, mesityl oxide, etc., is suppressed and the aimed high-purity compound is obtained industrially and efficiently.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides an industrially advantageous method for producing monochloroacetone by chlorinating acetone, which produces high-purity monochloroacetone with a low content of polychloroacetone and mesityl oxide. The present invention relates to a method for manufacturing the same.

[Conventional technology and its problems]

Monochloroacetone is a compound useful as a synthetic raw material for dyes, pigments, agricultural chemicals, insecticides, etc., and has long been known to be obtained by reacting acetone with chlorine.

The long-known method of introducing chlorine gas into liquid acetone tends to cause side reactions, especially the production of 1,1-dichloroacetone and mesityl oxide, which are difficult to separate from monochloroacetone, making it difficult to efficiently produce high-purity monochloroacetone. It was difficult to get to.

As a method to solve such problems, Japanese Patent Laid-Open No. 55-26
Publication No. 47 uses a container equipped with a distillation column as a reaction device, introduces chlorine into the upper part of the column where acetone is refluxed, performs a reaction with acetone, and removes by-product hydrogen chloride from the top of the column. A method is described in which monochloroacetone produced is separated by distillation from unreacted acetone and led to the lower part of the column.

However, although this method can reduce the amount of 1,1-dichloroacetone as a by-product, it has been found that depending on the type of condenser in the distillation column, it has the drawback of increasing the amount of mesityl oxide as a by-product.

In other words, the type of condenser shown in Fig. 2 produces a small amount of mesityl oxide as a by-product;
In the case where the condensate is led to the upper part of the condenser and returned to the distillation column (B) from the lower part of the condenser through the reflux return pipe (0), the acetone is removed from the dissolved hydrogen chloride in the reflux return pipe (D). It has been found that there is a problem in that a catalytic reaction produces mesityl oxide, which accumulates in the evaporation vessel (C). On an industrial scale, the type of condenser shown in Fig. 2 is not generally used due to poor cooling efficiency, and since the type shown in Fig. 1 is usually used, the method described in JP-A No. 55-2647 is not used industrially. It is difficult to implement it in a practical manner.

[Means for solving the problem] As a result of intensive studies to improve this problem, the present inventors have succeeded in producing monochloroacetone by reacting acetone and chlorine in a reaction apparatus as shown in Figure 1. In this process, an organic solvent with a lower boiling point than acetone and inert to chlorine and hydrogen chloride is added, and the organic solvent is refluxed in the upper stage of the distillation column, and chlorine is added to the middle stage of the column where the acetone is refluxed. (G), continuously introducing hydrogen chloride as a by-product from the top of the column, and guiding the produced monochloroacetone to the bottom of the distillation column while separating it from unreacted acetone by distillation. It was discovered that high purity monochloroacetone containing few impurities such as polychloroacetone and mesityl oxide can be efficiently obtained by this method, and the present invention was achieved.

When acetone and chlorine are reacted in the reaction apparatus equipped with the distillation column shown in Figure 1, hydrogen chloride produced as a by-product is extremely volatile and is immediately expelled from the distillation column.
When acetone is condensed in A), a large amount of hydrogen chloride is dissolved in acetone, and the solubility of hydrogen chloride in acetone is about 25% at 20°C. ), focusing on the fact that hydrogen chloride dissolved while remaining in the reflux return pipe (D) acts as a catalyst and mesityl oxide is produced as a by-product, and a third component with a lower boiling point than acetone is added. Therefore, instead of acetone, reflux was used at the top of the column to shorten the contact time between acetone and hydrogen chloride. As a result, it has become possible to obtain highly purified monochloroacetone with less mesityl oxide even with the apparatus shown in FIG.

The third component used in the present invention, that is, an organic solvent that has a lower boiling point than acetone and is inert to chlorine and hydrogen chloride under the reaction conditions, is a saturated halogen having 1 to 3 carbon atoms such as methylene chloride and isopropyl chloride. Examples include carbonated hydrocarbons and saturated hydrocarbons having 4 to 5 carbon atoms such as butane, pentane, and cyclobencune. When the organic solvent has a low boiling point, it is easy to separate it from acetone by distillation, but it is necessary to strengthen the cooling of the condenser. Furthermore, in the case of an organic solvent having a boiling point close to that of acetone, it is necessary to increase the number of plates in the distillation column, so it is practically preferable to use methylene chloride or isopropyl chloride.

The distillation column used in the present invention may be any column capable of distilling and separating acetone from an organic solvent having a boiling point lower than that of acetone, and from acetone and monochloroacetone.

Although the reaction in the present invention can be carried out either continuously or batchwise, an embodiment in which it is carried out batchwise will be described.

Acetone is charged into the evaporation vessel (C) of the reactor shown in FIG. 1, heated, and completely refluxed. A third component having a lower boiling point than acetone is charged until the top temperature falls to around the boiling point of the third component. However, if too much is charged, the acetone concentration near the chlorine charging stage will become low and the reaction will not proceed properly.

Chlorine is introduced continuously from the middle stage. The chlorine charging rate is adjusted so that the acetone refluxing near the chlorine charging stage is in excess of chlorine.

Hydrogen chloride, which is a by-product, is highly volatile and is therefore immediately led to the top of the column, where it is expelled from the system except for that which dissolves in the third component. Since the third component corresponding to the vapor fraction escapes from the system together with the hydrogen chloride that is expelled from the system, a corresponding amount of the third component is continuously added to the top of the column during the reaction.

The off-gas containing hydrogen chloride and the third component is led to an absorption tower in which water is circulated to recover the third component. Methylene chloride, isopropyl chloride, etc. have low solubility in water or hydrochloric acid water, so if the absorption tower is equipped with a heat exchanger that can remove the heat of absorption of hydrogen chloride into water, the absorbed liquid can be simply separated using a decanter. Most of it can be recovered. When the desired monochloroacetone is accumulated in the evaporation container (C), the supply of chlorine is stopped and the reaction is completed.

After stopping the chlorine preparation, heating is continued for a while, nitrogen is introduced to drive out hydrogen chloride in the system, and then heating is stopped. Distillation is carried out in the 0th stage to remove the third component, unreacted acetone, 1,3-dichloroacetone, etc. By separating the high boiling components, 1,1-dichloroacetone and high purity monochloroacetone containing less mesityl oxide can be obtained.

〔Effect of the invention〕

When producing monochloroacetone by reacting acetone and chlorine using the reactive distillation method, an organic solvent that has a lower boiling point than acetone and is inert to chlorine and hydrogen chloride is added and reacted at the top of the column instead of acetone. By this, the by-product of mesityl oxide is suppressed and high purity monochloroacetone is obtained.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

Example-1 10-stage older distillation column (B) with a diameter of 35+e+w
, 500- evaporation vessel (C) and condenser (A) are shown in Figure 2.
The reaction was carried out using the following combination of devices. First, 300 g of acetone was charged into an evaporation container and heated to completely reflux the acetone at normal pressure. Next, methylene chloride was charged from the top of the column and when the temperature at the top reached 42℃, chlorine was started to be charged from the fifth stage at a rate of L5Nl/Hr.During the zero reaction, the temperature at the top of the column was maintained at 40-42℃. Methylene chloride was continuously charged from the top of the tower. After 6 hours, the reaction was stopped. The reaction liquid composition in the evaporation container at that time was 15.6% acetone, 0.5% methylene chloride, 81.5% monochloroacetone, 1
．． Only traces of mesityl oxide were observed at 1.6% of 1-dichloroacetone and 0.8% of 1,3-dichloroacetone.

The reaction solution obtained in the same equipment as the reaction was distilled to yield 98.1% monochloroacetone and 1.9% 1.1-dichloroacetone.
% product was obtained.

Example-2 The reaction was started in the same manner as in Example-1, and 5 minutes after the start of the reaction.
After some time, haircetone was charged into the fifth stage of the distillation column at a rate of 60 g/Hr, and at the same time, the reaction liquid was withdrawn from the evaporation vessel at a rate such that the liquid level remained constant. Analysis of the composition of 20 hours worth of reaction liquid taken out from the evaporation container revealed that it was 26.0% acetone, 0.6% methylene chloride, 72.3% monochloroacetone, and 1.3% 1.1-dichloroacetone.
%, 1.3-dichloroacetone at 0.7%, only traces of mesityl oxide were observed.

Comparative Example A reaction was carried out in the same manner as in Example 1 except that methylene chloride was not charged.

The reaction solution composition after 6 hours of reaction was 12.3% acetone, 81.3% monochloroacetone, 1.7% 1.1-dichloroacetone, 0.8% 1.3-dichloroacetone, and 3% mesityl oxide. It was .6%. Although the reaction solution was distilled, only a product containing 93.9% monochloroacetone, 2.0% 1,1-dichloroacetone, and 4.0% mesityl oxide was obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a reaction apparatus used in the present invention, and FIG. 2 is a schematic diagram of a reaction apparatus without reflux return piping. A Condenser B Distillation column C Evaporation container D Reflux return pipe E Gas-liquid separator

Claims (1)

[Claims] In a method for producing monochloroacetone through the reaction of acetone and chlorine, an organic solvent that has a boiling point lower than that of acetone and is inert to chlorine and hydrogen chloride is added using a device equipped with a distillation column, a condenser, and a reflux return pipe. Then, the organic solvent is refluxed in the upper stage of the distillation column, and chlorine is continuously introduced into the middle stage of the column where acetone is refluxed to react with acetone, and hydrogen chloride as a by-product is refluxed from the top of the column. continuously remove,
A method for producing monochloroacetone, which comprises guiding the produced monochloroacetone to the lower part of a distillation column while separating it from unreacted acetone by distillation.