JPS6020377B2 - Method for producing ε-caprolactam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing gocaprolactam by subjecting cyclohexanone oxime to Beckmann rearrangement.

More specifically, the present invention relates to a compound obtained by Beckmann rearrangement of cyclohexanone oxime in the presence of boron trifluoride (BF3) or a complex thereof.

The present invention relates to a method for producing go-caprolactam (Lc) from a lactam/boron difluoride complex (Lc/BF3 rust). As a method for producing Lc by Beckmann rearrangement of cyclohexanone oxime, a method of heating cyclohexanone oxime with a key acid such as concentrated sulfuric acid, oleum, or polyphosphoric acid has been conventionally known. However, when such a mineral acid is used, it is necessary to neutralize it with an alkali when recovering the acid from the Beckmann rearrangement product, and a large amount of by-product salt is usually produced. Another method for recovering the rearrangement agent is to sufficiently dilute the Beckmann rearrangement product with water, extract and separate the buds contained therein, and dehydrate and concentrate the yuzu residue, but the recovery rate of Lc However, there were drawbacks such as insufficient heat energy and a large amount of thermal energy required. Methods using various rearrangement agents have been proposed to improve these drawbacks, but among them, BF
It is known that a method of applying No. 3 as a rearrangement agent to the Beckmann rearrangement of cyclohexanone oxime is effective. [J. ○rg. Chem. 20,1482-1490
(1955)] However, when using the above-mentioned rearrangement agent, the point of obtaining a high yield of LcBF3 and the point of recovering and recycling the rearrangement agent have not yet been sufficiently studied, and it is not necessarily an advantageous method. I couldn't say that.
Therefore, the inventors conducted intensive studies to improve these points, and as a result, they arrived at the present invention.

That is, this invention provides a process for producing an Lc·BF3 complex by Beckmann rearrangement of cyclohexanone oxime in the presence of BF3 or its key body;
Step of dissolving the liquid in aromatic hydrocarbon or halogenated hydrocarbon, introducing ammonia gas, and separating the solution from trifluoroammine boron (NHH3BF3) to obtain Lc; {C} Halogenation to NH3BF3 Add alkali metal and heat to 100 to 30,000,
Process of producing ammine salt of alkali metal halide and recovering BF3: {Improvement] Ammine salt of alkali metal halide is heated to 300-7000C to generate ammonia gas and alkali metal halide. The present invention relates to a method for producing Lc, which is characterized by comprising a step of recovering.

Next, each step of the method of the present invention will be specifically explained.

Wind-processed cyclohexanone oxime is subjected to Beckmann rearrangement in the presence of BF3 or its collar to produce an Lc.BF3 complex.

As the rearrangement agent BF3, for example, BF3 to which acetic acid, ethyl ether, or phenol is added can be used, but in particular BF3 to which aliphatic organic acid is added can be used.
Preference is given to using a tricomplex. The molar ratio of BF3 to cyclohexanone oxime is 0.1 or more, preferably 1.
It is 0 or more.

Although the rearrangement can be carried out without a solvent, it is generally carried out in a solvent. As a solvent, common organic solvents inert to BF3, such as liquid fatty acids such as acetic acid; benzene,
Aromatic hydrocarbons such as toluene, ethylbenzene, xylene, and cumene are used. Further, the rearrangement is usually preferably carried out at 50 to 150 qC, particularly 90 to 12 pi.

In addition, when the rearrangement agent is used in excess, the reaction can be carried out at a low temperature of 70 to 8,000 ℃. Further, the rearrangement is preferably carried out in an inert gas atmosphere under atmospheric pressure, reduced pressure or increased pressure, and is generally completed in 5 to 50 minutes. The BF3 anchor obtained in the previous step of the Tsukuda process is dissolved in aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene, and kyumene, and halogenated hydrocarbons such as chloroform and carbon tetrachloride, and ammonia gas is introduced. T-BF
The BF3 in the 3-anchor is separated as a precipitate of NH3BF3, while the liberated ratio is obtained from the solvent.

It is sufficient to introduce ammonia gas at a temperature around room temperature.
If ammonia gas is blown in too quickly, a part of the part to be liberated will be included in the precipitate of NH3BF3 that is produced, and if it is blown in too slowly, the reaction will take a long time, so although this varies depending on the equipment, usually the ammonia gas is blown in at 0. 1-1 evening/m
It is appropriate to introduce it at a ratio of in.

In addition, when introducing this ammonia gas, B was added as a rearrangement agent.
When F3 complex is used, the component added to BF3,
That is, it is necessary to remove acetic acid, ethyl ether, phenol, etc. by distillation or the like in advance.

It is also necessary to remove this in advance when the rearrangement is carried out in an acetic acid solvent, but when the rearrangement is carried out in an aromatic hydrocarbon solvent such as benzene, toluene, ethylbenzene, xylene, or cumene. In this case, ammonia gas can be introduced as is without removing those solvents. The Lc dissolved in the solvent is obtained by distilling off the solvent by a conventional operation such as distillation.

5 [C' Step: Add an alkali metal halide to NH3BF3 obtained in the previous step and heat it to 100 to 300 pm to generate an ammine complex salt of an alkali metal halide and recover BF3.

0 Effective examples of alkali metal halides include chlorides and bromides of calcium, magnesium, barium, and strontium.

When NH3BF3 and an alkali metal halide are mixed and reacted, it is desirable to separately pulverize the two and dry under reduced pressure to sufficiently remove water to prevent hydrolysis of BF3.

This reaction is carried out by heating to 100 to 300 degrees Celsius, adding 1 to 100 ml of water, and thoroughly stirring and mixing. NH3BF
The mixing ratio of 3 and the alkali metal halide is suitably in the range of 1:3 to 220 in terms of molar ratio.

Through this reaction, the alkali metal halide Fangmin-Tsuba salt is generated, and BF3 is generated. This BF3 is, for example, introduced into sufficiently dehydrated acetic acid and recovered as a choic acid complex of BF3, and is then re-processed. can act as a rearrangement agent for cyclohexanone oxime.

The ammine complex salt of alkaline earth metal halide obtained in the step before the pan step is further heated to a high temperature of 300 to 700 qC to recover ammonia gas and alkaline earth metal halide.

When the ammine complex salt of an alkali metal halide is heated, the complex salt gradually loses ammonia molecules, generates ammonia gas, and changes to an alkali metal halide.

The ammonia gas generated in this process is the BF of the Tsukuda process.
The alkali metal halide produced in this step is recycled to the reaction to produce NH3BF3 from NH3BF3 in the [C} step. be done.

As described above, Lc・BF obtained by Beckmann rearrangement of cyclohexanone oxime by carrying out the method of this invention
It is possible to produce almost quantitatively BF3, and at the same time, BF3, ammonia gas, and alkaline earth metal halide can be effectively recycled. Next, examples of this invention will be shown.

Example 1 BF
After adding 22.55 mmol (0.12 mol) of the acetic acid complex of No. 3 and sealing the surface with nitrogen, the three powders were heated to 110°C with a rope to carry out a rearrangement reaction. After the reaction was completed, the reaction The product was distilled to separate and collect 11.8 hours of acetic acid and 3.65 hours of acetic acid of BF3.

Note that the acetic acid complex of BF3 was used in circulation as part of the transfer agent. {B} Step Wind Dry ammonia gas was blown into the distillation residue (cumene solution of BF3) obtained in the step at room temperature at a flow rate of 0.35/min.

At the same time as the supply of ammonia gas started, the distillation residue became cloudy, a white precipitate of NH3BF3 began to form, and the liquid temperature gradually rose to a maximum of 5°C. After passing 3 rounds of dry ammonia gas, relax on a hot water bath for 30 minutes to create the ammonia gas in the liquid out of the system, and leave it to stand still for a few minutes to form a transparent cumene layer and a white precipitate layer. It was separated into The cumene layer was then distilled to Lcll. 26 (0.10 mol) and cumene 128' were obtained. On the other hand, the white precipitate layer was vacuum dried to obtain N-broad BF3. ■Step 'B} The fine powder of NH3BF3 obtained in the step 8.42 hours (0
．． 10 mol), vacuum-dried anhydrous magnesium chloride (
Add 95.2 moles (1.00 mol) of fine powder of MgC12), place it in a porcelain reactor equipped with a powder hawk, and heat it to 180 oo for 5 hours while thoroughly mixing it to release BF3 gas. At the same time, an ammine complex salt of magnesium chloride was obtained.

BF3 gas is absorbed into acetic acid to form BF3 acetate body 13
．． 46 was obtained, and this was used for circulation as a rearrangement agent in the wind process. ■Step 'C} The temperature of the magnesium chloride ammine tsuba salt obtained in step 'C' was further raised and heating was continued for 5 hours at 650 qo to generate 1.26 mol of ammonia gas (0.07 mol) and magnesium chloride. I got it.

Ammonia gas is NH3 from the Lc/BF3 rust body in the Tsukuda process.
In the reaction that produces BF3, magnesium chloride is also
They were each recycled and used in the reaction of producing ammine salt of magnesium chloride from NH8BF3 in Step I. Example
Step 2 (2) and Step 'B} were each carried out in the same manner as in Example 1.

■Step [B] The fine powder with an N ratio of 8.42 molar (0.10 mol) obtained in step [B] was added with vacuum-dried anhydrous calcium chloride (CaC12
111.0 molar powder (1.00 mol) of BF3 gas was added thereto, and heated to 15,000 mA for 5 hours with thorough mixing in a porcelain reactor to produce 4.73 molar powder (0.07 mol) of BF3 gas. ) was generated and ammine tsuba salt of calcium chloride was obtained.

BF3 gas was absorbed into acetic acid and recycled to the wind process as a BF3 acetate complex. The ammine lead salt of calcium chloride obtained in the plate step {C} step was further heated to 65,000 ℃ for 5 hours, and heating loss was continued to generate 1.21 mol of ammonia gas (0.07 mol) and calcium chloride. I got it.

Claims (1)

[Claims] 1 (A) Step of purifying ε-caprolactam/boron trifluoride complex by Beckman rearrangement of cyclohexanone oxime in the presence of boron trifluoride or its complex; (
B) Dissolve the ε-caprolactam/boron trifluoride complex in an aromatic hydrocarbon or halogenated hydrocarbon, introduce ammonia gas, and separate the ε-caprolactam solution from trifluoroammine boron to obtain ε-caprolactam. Step of (C) adding alkaline earth metal halide to trifluoroammine boron to give a
℃ to generate ammine complex salt of alkaline earth metal halide and recover boron trifluoride; (D
) Ammine complex salt of alkaline earth metal halon 300
A method for producing ε-caprolactam, comprising the steps of heating to ~700°C to recover ammonia gas and alkaline earth metal halide.