JP3263965B2 - Oxime production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing oximes. Specifically, in producing the corresponding oxime from a ketone or aldehyde and a hydroxylamine salt,
The present invention relates to a novel method for producing an oxime without by-products of inorganic salts such as ammonium sulfate.

[0002]

2. Description of the Related Art For example, cyclohexanone oxime is industrially useful as an intermediate material for producing caprolactam, which is a nylon material, and is usually produced by reacting cyclohexanone synthesized by each method with hydroxylamine. It is produced by.

[0003]

However, in this method, it is necessary to use hydroxylamine as an inorganic acid salt such as sulfate or hydrochloride in view of the stability of hydroxylamine. Must be neutralized with alkali. As a result, a large amount of inorganic salts such as ammonium sulfate are inevitably produced as by-products together with the intended cyclohexanone oxime. Therefore, there has been a demand for a method for producing cyclohexanone oxime having no by-product of an inorganic salt such as ammonium sulfate, and some methods have been proposed, but a method that can be said to be sufficient has not been found yet.

[0004]

Means for Solving the Problems In view of the above circumstances, the present inventors have studied for the purpose of suppressing the production of ammonium sulphate in the reaction of producing an oxime from a hydroxylamine salt and a ketone or an aldehyde. Separation of the salt aqueous solution and ketone or aldehyde by a cation exchange membrane, the diffusion and migration of hydroxylamine as an ammonium ion into the ketone or aldehyde phase, followed by the formation of the oxime in the ketone or aldehyde phase. Discovered and reached the present invention.

That is, the gist of the present invention is that a hydroxylamine salt aqueous solution phase and a ketone or aldehyde phase are separated by a cation exchange membrane, and the hydroxylamine in the hydroxylamine salt aqueous solution phase is converted to a ketone or aldehyde phase through the membrane. The present invention relates to a method for producing an oxime, which comprises diffusing and transferring an oxime in a ketone or aldehyde phase.

Hereinafter, the present invention will be described in detail. Examples of the hydroxyalamine salt used in the present invention include a sulfate, a hydrochloride, a phosphate and a formate, and a sulfate is generally used. The concentration of the aqueous solution of the hydroxylamine salt is usually 5 to 60% by weight, preferably 1 to 60% by weight.
0 to 50% by weight. An efficient reaction cannot be expected at a concentration lower than the range, and conversely, at a concentration higher than the range,
It is not preferable because hydroxylamine is precipitated.

On the other hand, the ketone to be used in the present invention may be any of aliphatic, alicyclic and aromatic compounds, and examples thereof include cyclohexanone, cyclododecanone, acetone, dimethylacetone, acetophenone, benzophenone and the like. . Examples of the aldehydes include acetaldehyde, propionaldehyde, butyraldehyde, caproaldehyde, benzaldehyde, and anisaldehyde. Among these ketones and aldehydes, cyclohexanone, which is a raw material for caprolactam, is typically mentioned industrially. The amount of the ketone or aldehyde phase used varies depending on the reaction system, but is usually 0.1 to 10 times, preferably 0.5 to 5 times the volume of the aqueous hydroxylamine salt solution phase.

The cation exchange membrane used in the present invention includes:
It is based on a membrane made of a synthetic resin and has a cation exchange group introduced therein, and is conventionally known as an ion exchange membrane. The cation exchange group has a strong acid type ion exchange group and is generally a sulfonic acid group, and is used as a free acid type in the present invention. The exchange capacity of the exchange membrane is not particularly limited, but is usually 0.1 to 10 meq.
/ G · dry resin, preferably 0.5 to 3 me
q / g · dry resin. Examples of the base resin for forming the exchange membrane include an acrylonitrile-vinyl chloride copolymer, a styrene-divinylbenzene copolymer and a modified ethylene tetrafluoride polymer.
The thickness of the cation exchange membrane is usually 0.05 to 3 m.
m, preferably about 0.2 to 2 mm. Commercially available cation exchange membranes can be used as they are. The reaction temperature is usually from 10 to 100 ° C, preferably from 20 to 80 ° C. The reaction time is usually 0.5% depending on the area of the cation exchange membrane in contact and the exchange capacity.
It is appropriately selected from a wide range of ~ several hundred hours. Further, the reaction pressure may be normal pressure, but if necessary, a hydroxylamine salt aqueous solution phase may be used as a pressurized system.

In the reaction of the present invention, the hydroxylamine salt aqueous solution phase and the ketone or aldehyde phase are separated by a cation exchange membrane, so that the ketone or aldehyde phase can be selectively converted into ammonium ions from the hydroxylamine salt aqueous solution phase. The acid diffuses into the cation exchange membrane, reacts in the ketone or aldehyde phase, generates the corresponding oximes, and releases the acid in the aqueous hydroxylamine salt solution phase.

[0010] As a reaction system, basically, a reactor having a space divided into two by an ion exchange membrane is used, a hydroxylamine salt aqueous solution is charged into one, and a ketone or aldehyde liquid is charged into the other. Alternatively, each phase is circulated and extracted in a continuous manner. Further, a flow operation method using a reactor having a plurality of chambers partitioned by an ion exchange membrane reinforced by a mesh-like support material can also be adopted.

After completion of the reaction, the oxime can be easily separated and recovered from the mixture containing the oxime on the ketone or aldehyde phase side by distillation crystallization or extraction. The ketone or aldehyde after separation can be recycled and used in the reaction system. Further, when a small amount of acid is mixed in the ketone or aldehyde phase, the oxime may be recovered after treating the acid by neutralization or the like.

On the other hand, the acid liberated in the aqueous hydroxylamine salt phase is preferably recovered and reused without neutralization. That is, without isolating the acid, an aqueous solution of a hydroxylamine salt having an increased concentration of a free acid, for example, sulfuric acid, is recovered and used as a solvent, and if necessary, a solution mixed with concentrated sulfuric acid as a solvent. By reacting nitrogen oxide and hydrogen, a hydroxylamine salt as a raw material can be produced. As shown from the above description, when industrially producing oximes using the present invention, for example,
What is necessary is just to employ the process shown in FIG.

The reactor 1 is divided by an ion exchange membrane 2, and an aqueous solution of a hydroxylamine salt is supplied to one 1 a from a conduit 3, and a ketone or aldehyde is supplied to the other 1 b from a conduit 4. Then, a free acid is generated on the hydroxylamine salt aqueous solution side (aqueous phase side) 1a, and a part of the aqueous solution containing the free acid and the unreacted hydroxylamine salt is passed through the conduit 5 to the hydroxylamine salt synthesis system 6. return. Examples of a method for synthesizing a hydroxylamine salt include a method of catalytically reducing nitric oxide with hydrogen in a dilute aqueous solution of a mineral acid such as sulfuric acid in the presence of a suspended platinum-supported catalyst. The reaction is usually carried out at a temperature of from 40 to 80 ° C. under normal pressure to under pressure. The hydroxylamine salt produced in the synthesis system may be supplied from the conduit 3 to the aqueous phase side 1a of the reactor.

On the other hand, since an oxime is formed on the ketone or aldehyde side (oil phase side) 1b, a part of the mixture of the oxime and the unreacted ketone or aldehyde is transferred to the conduit 7
The oxime is recovered from the conduit 9 in the separation system 8. As a specific separation means of the separation system 8, a vacuum distillation method is exemplified. Further, in order to remove a trace amount of acid mixed in the oil phase, it is preferably neutralized with a small amount of alkali before performing distillation (not shown). The remaining ketone or aldehyde after separating and recovering the oxime is circulated through the conduit 4 to the oil phase side 1b of the reactor. At this time, a ketone or aldehyde corresponding to the oxime produced and recovered may be newly supplied from the conduit 10.

[0015]

EXAMPLES Next, the present invention will be described 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 In the center of a 200 ml glass container, a sulfonic acid type ion exchange membrane (H ⁺ type, acrylonitrile-vinyl chloride copolymer type polymer, film area 33 cm ² , film thickness 0.6 m) was placed.
m, exchange capacity 2.7 meq / g · dry resin)
85 ml of a 5.0 N aqueous solution of hydroxylamine sulfate was charged into one of the two, and
0.4 g was charged, and each phase was allowed to stand at 25 ° C. for 5 hours while stirring. After that, the liquid of each phase was analyzed by gas chromatography, and as shown in Table 1, formation of 0.018 mol of cyclohexanone oxime was confirmed in the cyclohexanone phase (oil phase) (oxime with respect to the charged hydroxylamine equivalent). Is 4.2%).
No other by-products were formed. On the other hand, in the hydroxylamine sulfuric acid aqueous solution phase (hydrogen), almost the same amount of free sulfuric acid as the generated oxime was confirmed.

Examples 2 to 4 The results obtained in the same manner as in Example 1 except that the reaction temperature or the thickness of the ion exchange membrane was changed in Table 1 are shown in Table 1.
It is shown in FIG. No by-products other than cyclohexanone oxime were produced.

[0017]

[Table 1]

[0018]

According to the present invention, the desired oximes can be obtained in the ketone or aldehyde phase simply by separating the aqueous phase of hydroxylamine salt and the phase of ketone or aldehyde by a cation exchange membrane and holding the resulting phase in the liquid phase. Is obtained.
The reason is that hydroxylammonium ions from the aqueous hydroxylamine salt solution phase selectively pass through the membrane by ion exchange and diffuse into the ketone or aldehyde phase, and such a phenomenon is caused by the cation exchange membrane. Is completely unexpected and surprising.
As a result, in the present invention, by-products (free)
The resulting acid remains in the aqueous hydroxylamine salt solution phase, so that the acid can be recovered as it is without being neutralized and reused. Therefore, in the present invention, the generation of by-product salts can be reduced to zero. On the other hand, the produced oxime can be obtained in a free state, not as an acid salt, so that it can be separated and recovered without a by-product of salt due to neutralization.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a process for producing an oxime of the present invention.

[Explanation of symbols]

 1: reactor 1a: reactor (aqueous phase side) 1b: reactor (oil phase side) 2: ion exchange membrane 3, 4, 5, 7, 9, 10: conduit 6: hydroxylamine salt synthesis system 8: oxime Separation system

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsutomu Yonemori 1-1 Kurosaki Castle Stone, Yahata-nishi-ku, Kitakyushu City Inside the Kurosaki Plant of Mitsubishi Chemical Co., Ltd. (56) References JP-A-63-164653 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) C07C 249/08 C07C 251/44

Claims (3)

(57) [Claims] 1. A method for separating a hydroxylamine salt aqueous solution phase and a ketone or aldehyde phase with a cation exchange membrane,
A method for producing an oxime, comprising diffusing and transferring hydroxylamine in a hydroxylamine salt aqueous solution phase to a ketone or aldehyde phase through the membrane to generate an oxime in the ketone or aldehyde phase. 2. A ketone or aldehyde phase containing the generated oxime is withdrawn from the ketone or aldehyde phase side (1b) of the reactor, and the oxime is separated and recovered, and the remaining liquid is separated from the ketone or aldehyde phase side (1b) of the reactor. 2.) The method of claim 1 wherein said method is circulated. 3. A hydroxylamine salt aqueous solution is withdrawn from a hydroxylamine salt aqueous solution phase side (1a) of a reactor, supplied to a hydroxylamine salt synthesis system, and a reaction solution from the synthesis system is converted into a hydroxylamine salt aqueous solution phase of the reactor. Method according to claim 1, circulating to the side (1a).