JPH0225457A - Production of oximes - Google Patents

Abstract

PURPOSE:To obtain the subject compounds useful as an intermediate, etc., at a high recovery ratio by reacting ketones, etc., with a mineral acid salt of hydroxylamine in the presence of a specific alcoholic organic solvent in an aqueous medium and extracting the reaction product into an organic solvent phase. CONSTITUTION:Ketones (e.g., cyclohexanone) or aldehydes are reacted with a mineral acid salt of hydroxylamine in an aqueous medium in the presence of an organic solvent (e.g., dichloroethanol, trichloroethanol, butanol or pentanol) selected from 2-4C halogenated aliphatic alcohols, 4-10C aliphatic alcohols and phenols in the reaction system and the formed oximes are extracted into an organic solvent phase and recovered. Since the amount of the oximes remaining in the aqueous phase is extremely small by the above-mentioned method, the aqueous phase can be utilized as a mineral acid source in various chemical plants.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing oximes.
The present invention relates to a method for producing corresponding oximes from ketones or aldehydes and hydroxylamine mineral salts without producing by-products of inorganic salts.

[Conventional technology]

For example, cyclohexanone oxime is useful as an intermediate for ε-caprolactam, which is a raw material for nylon, and is industrially produced in large quantities. It is usually produced by reacting cyclohexanone and hydroxylamine. However, since hydroxylamine is unstable in its own form, it is used in the form of mineral acid salts such as sulfate for boat fishing, and as a result, mineral acids such as sulfuric acid are produced as by-products in the oxime formation reaction, resulting in the formation of mineral acids in the system. The pH of is strongly acidic. In a normal oxime formation reaction, if the pH in the system is strongly acidic, the oxime formation reaction is an equilibrium reaction, so the reaction cannot be completed sufficiently, and the oximes produced are relatively soluble in the acid aqueous solution. Since the reaction mixture is easily separated into an oil phase containing oximes and an aqueous phase, it is difficult to separate the reaction mixture into an oil phase containing oximes and an aqueous phase. Therefore, conventionally, in the above oxime formation reaction, a neutralizing agent such as ammonia is added to the system. A method has been adopted in which the reaction is carried out by adjusting the pH of the solution to 9 or higher. In short, in this method, the mineral acid produced as a by-product is neutralized, which shifts the equilibrium and further progresses the oximation reaction. This has the advantage of preventing the oximes from dissolving therein and allowing the reaction mixture to be well separated into an oil phase and an aqueous phase.

However, in this conventional method, a large amount of inorganic salt is naturally produced as a by-product. For example, when a hydroxylamine sulfate is used and ammonia is used as a neutralizing agent, an extremely large amount of ammonium sulfate is produced as a by-product. However, since inorganic salts such as ammonium sulfate are substances with low economic value, in recent years there has been a demand for a method for producing oximes that does not involve the by-product of inorganic salts.

For example, if by-product mineral acid could be recovered as an aqueous solution without adding a neutralizing agent such as ammonia to the reaction system, this aqueous mineral acid solution could be effectively used in processes that use mineral acids in various chemical synthesis plants. be able to. Therefore, a method can be considered in which a water-immiscible organic solvent is added to the reaction system instead of a neutralizing agent, and the reaction is carried out while the generated oximes are extracted into the organic solvent phase. That is, by extracting oximes into an organic solvent phase, the equilibrium of the oxime formation reaction is shifted and the separation property between the oil phase and the aqueous phase of the reaction mixture is improved. Conventionally, known organic solvents for extracting oximes include, for example, benzene, toluene, cyclohexane, diethyl ether, and butyl acetate.

However, when conventionally known organic solvents are used,
A considerable amount of ketones or aldehydes are also extracted with the oximes to be extracted, and the extraction rate of the oximes themselves is also low, especially when the aqueous phase is an acid aqueous solution like the 7-year-old oxime reaction mixture. could not be called expensive.

[Problem that the invention seeks to solve]

In view of the above circumstances, the present inventors have developed a method for producing oximes in which the produced oximes are extracted in the presence of an organic solvent without adding a neutralizing agent to the oxime formation reaction system.
As a result of various studies aimed at obtaining an organic solvent with a high extraction rate of oximes and a slightly lower extraction rate of ketones or aldehydes when extracting a predetermined amount of oximes, we found that a specific alcohol-based organic solvent The present invention was completed by discovering that by selecting a suitable material, the object of the present invention can be achieved and oximes can be obtained with a high recovery rate.

[Means for solving problems]

That is, the gist of the present invention is that when producing the corresponding oximes by reacting ketones or aldehydes with hydroxylamine mineral salts in an aqueous medium, the reaction system or the reaction mixture or after separating the same into liquids. In the aqueous phase of 02~
A method for producing oximes, which is characterized by adding at least one organic solvent selected from halogenated aliphatic alcohols of No. 4, aliphatic alcohols of Nos. 04 to 10, and phenols, and extracting the oximes into the organic solvent phase. It depends on the manufacturing method.

Hereinafter, the configuration of the present invention will be explained in detail.

Ketones or aldehydes that serve as raw materials for the present invention usually include ketones such as cyclohexanone, cyclododecanone, acetone, dimethylacetone, and acetophenone, and aldehydes such as benzaldehyde and acetaldehyde. On the other hand, examples of hydroxylamine mineral salts include sulfates, phosphates, hydrochlorides, and nitrates, with sulfates being common. The ratio of hydroxylamine mineral salt to ketones or aldehydes is usually 3 times the mole of O,S~/.
It is desirable to use approximately equimolar amounts.

The above-mentioned ketones or aldehydes and hydroxylamine mineral salts are reacted in an aqueous medium, and the amount of water in this reaction is usually /~S times the weight of the hydroxylamine mineral salts. Note that this water is usually supplied to the reaction system as an aqueous solution of hydroxylamine mineral salt.

In the first aspect of the present invention, a halogenated aliphatic alcohol selected from 02 to 4 C4 to 1° aliphatic alcohol and phenols is produced without adding an alkali as a neutralizing agent into the reaction system. The presence of at least one organic solvent is an essential requirement. That is, the reaction is carried out while extracting the produced oximes in the aqueous phase into an organic solvent without neutralizing the mineral acids produced as by-products in the oxime formation reaction.

Specific examples of the organic solvent used in the present invention include 02-4 halogenated aliphatic alcohols such as dichloroethanol, trichloroethanol, monobromoethanol, monochrome 0-jso-phenolic tanol, n-butanol, and ethanol. butanol, souptanol,
C4-10% preferably 04-8 aliphatic alcohols such as n-pentanol, coventanol, cyclopentanol, n-hexatol, cyclohexanol, -monoethylhexatol, n-octatool, n-decanol; and phenols such as phenol, cresol, inglobilphenol, chlorophenol, and dichlorophenol, among which butanol and pentanol are particularly preferred. The amount of this organic solvent used is usually θ, /~-0 times the weight of the aqueous medium, preferably /dO
, r - left weight times. If the amount of organic solvent used is too small, the produced oximes cannot be extracted well, and on the other hand, if it is too large, the separation operation from the oximes becomes troublesome.

In the present invention, by using the above-mentioned organic solvent, the produced oximes are successfully extracted into the organic solvent phase, despite the presence of by-product mineral acids in the aqueous phase.

However, in the present invention, it is desirable to further add a small amount of inorganic salt to the reaction system, since this further promotes the extraction of oximes into the organic solvent phase. In short, this is because the solubility of oximes in the aqueous phase decreases due to the salting out effect of the inorganic salt. Examples of this inorganic salt include ammonium sulfate, ammonium phosphate, ammonium hydrochloride, ammonium nitrate, and the like, with ammonium sulfate being common. The amount of this inorganic salt added is usually S to q with respect to the aqueous medium.
o% by weight.

The oximation reaction can be carried out under normal pressure or increased pressure, and the reaction temperature is usually 0 to 720°C, preferably 20 to 90°C. Although the reaction can be carried out either continuously or batchwise, the continuous method is employed industrially. In the case of a continuous method, there is usually a stirring reaction tank (mixer) for uniformly mixing the reaction components and performing the oxime conversion reaction, and a separation tank (mixer) for separating the reaction mixture into an aqueous phase and an oil phase. A countercurrent reactor such as a packed column or a rotating disk reactor may be used. The number of reaction stages is selected as appropriate, and is, for example, 1 to 0 stages. In addition, in the case of a continuous multi-stage reaction, ketones or aldehydes and hydroxylamine mineral salts may be brought into contact with each other in parallel flow, but usually the organic solvent phase containing ketones or aldehydes and the hydroxylamine mineral salts A method in which the reaction is sequentially carried out by bringing the reaction mixture into contact with an aqueous phase containing an aqueous solution in a countercurrent manner is preferred.

After the reaction is completed, the separated organic solvent phase mainly contains oximes, and therefore the dioximes can be easily recovered by distilling the oximes. Further, if necessary, some acid contained in the organic solvent phase before distillation may be neutralized with an alkali such as ammonia.

The organic solvent from which the oximes have been separated is recycled and used in the oxime formation reaction. On the other hand, since the aqueous phase is an aqueous mineral acid solution containing almost no oximes, it can be strained and effectively used in processes using mineral acids in various chemical synthesis plants.

The first aspect of the present invention is that instead of adding the organic solvent used in the oximation reaction, the organic solvent is added directly to the reaction mixture after the reaction is completed, or this mixture is added to the aqueous phase and the oil phase. It is essential that it be added to the aqueous phase after separation. That is, the oximes produced in the oxime formation reaction are brought into contact with the organic solvent used in the seventh aspect of the invention after the reaction, thereby extracting the oximes into the organic solvent phase. Through this extraction, the oximes are efficiently transferred to the organic solvent phase, and the oximes can be recovered at a high recovery rate.

The amount of the organic solvent used for extraction is usually 0 to 10 times the weight of the aqueous medium or separated aqueous phase in the reaction mixture, preferably o,s -5 times the weight. The temperature of extraction is usually 0 to 7°C, preferably λo-'yθ°C. Extraction can be carried out either continuously or batchwise, and usually
A combination of a mixer and a settler, or a countercurrent extraction device such as a packed column or a rotating disk reactor is used. The number of extraction stages is 7 stages or, for example, multiple stages of - to IO stages. Since most of the oximes are extracted into the organic solvent phase obtained after the extraction, the oximes can be easily isolated and recovered by distilling this. Also,
Since the aqueous phase contains almost no oximes,
This can be applied to various fields as a mineral acid raw material.

In addition, when carrying out by a continuous method, it is also possible to carry out the first invention in the reaction step and the second invention in the extraction step in combination. In this case, the concentration of oximes in the aqueous phase can be further reduced by performing an extraction treatment with a fresh organic solvent before supplying the aqueous phase obtained by the liquid separator into the reaction system. Extraction in this case can be carried out in a similar manner to the above reaction.

Further, although the aqueous phase contains a small amount of unreacted ketones or aldehydes, according to the present invention, such unreacted substances can also be recovered at the same time.

〔Example〕

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

Example/According to the flow shown in Figure 1, a cyclohexanone/organic solvent mixture and an aqueous hydroxylamine sulfate solution were brought into countercurrent contact in a three-stage reaction process in which a stirred reactor and a separator were combined to form cyclohexanone oxime. was manufactured. Then, the organic solvent phase from the final step is distilled to recover cyclohexanone oxime, while the aqueous phase is recovered after countercurrent extraction with the organic solvent in three stages, and this organic solvent is transferred to the first reactor/a. supplied.

That is, cyclohexanone Sθ09/hr from 6 in the figure to the first reactor/a and the first liquid separator/θ for the extraction step described later.
The organic solvent phase n-butanol from b and the aqueous phase (containing hydroxylamine sulfate and ammonium sulfate) from the second reaction separator 2b were supplied, and the mixture was stirred in a nitrogen gas atmosphere at a temperature of 75°C. After carrying out the reaction so that the average residence time is 70 minutes, this is fed to the first reaction separator/b to separate the aqueous phase and the organic solvent phase, and then the organic solvent phase is separated into the second reaction separator/b. The mixture was supplied to the reactor 2a, mixed with the aqueous phase from the third reaction separator 3b, and reacted under the same conditions as the first reaction. Further, hydroxylamine sulfate and ammonium sulfate were added to the third reactor 3a at a rate of '1. ON and 3. An aqueous solution of 15θθml/J1r prepared by dissolving in ON is supplied from the bottom of the figure, mixed with the organic solvent phase from the first reaction separator 2b, and reacted under the same conditions as the first reaction. 3 reaction separator 3
b, to separate the aqueous phase and the organic solvent phase, and then, the aqueous phase is supplied to the second reactor 2a, and the organic solvent phase is neutralized with a small amount of ammonia (not shown), and then distilled. Tower S
Dicyclohexanone oxime was recovered from the bottom of the tower by distilling it under reduced pressure.

Further, the aqueous phase from the first reaction separator/b is supplied to the extractor 10a, and extracted with the organic solvent phase from the second reaction separator//b under the same conditions as the first reaction. The aqueous phase and the organic solvent phase were separated into a water phase and an organic solvent phase, and the organic solvent phase was then fed to the 1' reactor/a. On the other hand, the aqueous phase is transferred to the λth extractor/
/a1 Second liquid separator//b1 Third extractor/core a and third extractor/2a are sequentially supplied, and the third extractor/2a is supplied with / in the figure.
New n-buta vine supplied from 3/000 g/
Finally, an aqueous phase consisting of an aqueous sulfuric acid solution was recovered.

In the above method, the recovery rate of cyclohexanone oxime (yield relative to cyclohexanone) recovered from the distillation column S and the recovery rate of unreacted cyclohexanone are determined, and the cyclohexanone in the aqueous phase finally recovered is determined. The concentrations of oxime and cyclohexanone were determined and the results shown in Table 1 were obtained.

Table 1 shows the results obtained when the reaction was carried out in exactly the same manner as in Example 1, using the same amount of n-pentanol instead of n-butanol as the organic solvent.

Table 1 shows the results when the reaction was carried out in exactly the same manner as in Comparative Example/Example/, using the same amount of toluene instead of n-butanol as the organic solvent.

OXM Nidichlohexanone oxime CHN Nidichlohexanone Examples 3-g and Comparative Examples Cyclohexanone/91. g and hydroxylamine sulfate 11. ON and ammonium sulfate3. An aqueous solution OAr l adjusted to contain oN was charged and heated to qs℃ under stirring.
The reaction was carried out for 20 minutes at a temperature of . The production rate of cyclohexanone oxime in this reaction was 2% g, and unreacted cyclohexanone was still 7 g%. Next, this reaction mixture was separated into an aqueous phase and an oil phase, and 9% of cyclohexanone oxime was in the oil phase, and 33% of cyclohexanone oxime was in the aqueous phase.
Still, 77% of cyclohexanone was contained in the oil phase and 7% in the water phase.

The composition of the aqueous phase was analyzed and was as shown in Table 2.

For Table 2, the organic solvent sog shown in Table 3 was mixed at u, t°C.
Extraction was carried out by stirring for 75 minutes at a temperature of The results shown in Table 3 were obtained.

The aqueous phase obtained in the above reaction and having the composition shown in Table 2/
o o ticOXM: CHN=gλ, 3mol2/7.
7 mol) [Effect of the invention] According to the present invention, when producing the corresponding oximes by reacting ketones or aldehydes with hydroxylamine mineral salts in an aqueous medium, the reaction system or reaction mixture or By adding a specific organic solvent to the aqueous phase after separation, oximes can be extracted into the organic solvent phase with a high recovery rate. Therefore, since the amount of oximes remaining in the aqueous phase is extremely small, the aqueous phase can be used as a mineral acid source in various chemical plants.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow sheet outlining the reaction steps in Examples of the present invention. Applicant: Mitsubishi Kasei Co., Ltd. Agent: Patent Attorney Haseguki et al.

Claims (2)

[Claims] (1) When producing the corresponding oximes by reacting ketones or aldehydes with hydroxylamine mineral salts in an aqueous medium, a halogenated aliphatic alcohol of C_2_ to_4 and a halogenated aliphatic alcohol of C_4_ to_1_0 are added to the reaction system. A method for producing oximes, which comprises carrying out the reaction while extracting the produced oximes into the organic solvent phase in the presence of at least one organic solvent selected from aliphatic alcohols and phenols. (2) When producing the corresponding oximes by reacting ketones or aldehydes with hydroxylamine mineral salts in an aqueous medium, directly into the reaction mixture or separating the reaction mixture into an aqueous phase and an oil phase. C_2_～_4 in the aqueous phase after
An oxime characterized in that oximes are extracted and recovered into an organic solvent phase by adding at least one organic solvent selected from halogenated aliphatic alcohols of C_4_ to_1_0 and aliphatic alcohols of C_1_0 and phenols. kind of manufacturing method.