JPS6020382B2 - Production method of ε-caprolactam - Google Patents

Description

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

More specifically, the present invention provides z-caprolactam obtained by Beckman rearrangement of cyclohexanone oxime in the presence of boron trifluoride or its adduct. The present invention relates to a method for producing caprolactam (hereinafter referred to as lactam) from boron trifluoride body (hereinafter referred to as lactam body). As a method for producing a lactam by subjecting cyclohexanone oxime to Beckmann rearrangement, a method of heating cyclohexanone oxime with a mineral acid such as concentrated sulfuric acid, oleum, or polyphosphoric acid has been known.

However, when such a key acid is used, it is necessary to neutralize it with an alkali when recovering the lactam from the Beckmann rearrangement product, and a large amount of created salt is usually produced. Therefore, methods using various rearrangement agents have been proposed as improvements to this method, but among them, a method in which boron trifluoride and its adducts are used as a rearrangement agent for the Betzkmann rearrangement of cyclohexanone oxime is particularly effective. It has been known.

[J. org, Chem, 20, 1482-1490 (
[1955]] However, according to this method, the rearrangement product is obtained as a lactam complex, and it is therefore necessary to liberate the lactam from it. Therefore, the inventors conducted intensive studies on a method of decomposing lactam bodies using a solvent to obtain lactams, and as a result, they arrived at the present invention. That is, in a method for producing a lactam by Beckmann rearrangement of cyclohexanone oxime in the presence of boron trifluoride or its adduct, the inventors added dimethyl sulfoxide, dimethylformamide, and dimethylacetamide to the obtained lactam compound. This relates to a method for producing lactams, which comprises adding a decomposition solvent selected from the group consisting of a decomposition solvent and an extraction solvent selected from the group consisting of benzene and alkylbenzene, separating the liquid into two layers, and obtaining the lactam from the upper layer. be.

The lactam fin used in this invention is obtained by Beckmann rearrangement of cyclohexanone oxime in the presence of boron trifluoride or an adduct thereof.

In the presence of boron trifluoride or its adduct as a rearrangement agent, for example, an acetic acid adduct, an ethyl ether adduct, a phenol adduct, etc. can be used, but the use of an aliphatic organic acid is particularly advantageous. The molar ratio of boron trifluoride to cyclohexanone oxime is 0.1 or more, preferably 1.0 or more.

Although the rearrangement can be carried out without a solvent, it is generally carried out in a solvent.

As a solvent, ordinary organic solvents that are inert to boron trifluoride, such as liquid fatty acids such as acetic acid, benzene,
Aromatic hydrocarbons such as toluene, xylene and cumene are used. Further, the rearrangement is usually preferably carried out at 50 to 15 pi, particularly preferably from 90 to 12 pi.

In addition, when using an excessive amount of rearrangement agent, 70 to 80q
It can also be carried out at low temperatures such as ○. 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. This rearrangement product is a lactam complex, which in turn
A decomposition solvent selected from the group consisting of dimethyl sulfoxide, dimethylformamide, and dimethylacetamide is added to decompose the lactam enantiomer to liberate the lactam, and the lactam is extracted with an extraction solution consisting of benzene and alkylbenzene to obtain the lactam. . When the lactam body is present, the extraction solvent and the decomposition solvent form two layers at a mixing ratio in which the former solvent has a molar fraction of about 80 mol% or more relative to both solvents, and the extraction solvent forms the upper layer. , the decomposition solvent separates into the lower layer.

The lactam body is mixed with the decomposition solvent at an arbitrary ratio,
Although it is easily decomposed into lactam at room temperature or slightly overflowing, this operation is preferably carried out in a dehydrated state as much as possible in order to suppress the hydrolysis of boron trifluoride.

In addition, when performing this decomposition and extraction operation, when an adduct of boron trifluoride is used as a rearrangement agent, components other than boron trifluoride that constitute the adduct, namely acetic acid,
Ethyl ether, phenol, etc. must be removed in advance by distillation or the like.

Also, when the rearrangement is carried out in an acetic acid solvent, it is necessary to remove acetic acid beforehand, but when the rearrangement is carried out in an aromatic hydrocarbon solvent such as benzene, toluene, xylene, or kyumene, The lactam can be used as it is for this decomposition and extraction operation without removing these solvents.The lactam extracted into the upper layer can be obtained by distilling off the extraction solvent by a conventional operation such as distillation.

The undecomposed lactam chains dissolved in the upper and lower layers are separated by vacuum distillation and recycled to the decomposition and extraction steps. As mentioned above, "Decomposition by the method of this invention,
By repeating the extraction process two or more times, lactam can be produced from the lactam body at a yield of about 80%. Next, examples of this invention will be shown.

Example 1 (First operation) Lactam collar body 20. Abbreviation: dimethyl sulfoxide 15. The solution was dissolved in about 20% of cumene (84.2 mol %), shaken vigorously at room temperature for 30 minutes, and then left to stand still for 10 minutes to separate into two layers.

The upper layer (cumene layer) was separated and cumene was distilled off, followed by distillation under reduced pressure to obtain 7.81 g of lactam (yield: 60.5
%) and 2.03 g of lactam body as a pot residue were obtained. On the other hand, the lower layer (dimethyl sulfoxide layer) was distilled to remove dimethyl sulfoxide, and then distilled under reduced pressure to form the lactam complex 6.
I got a foundation. (Second operation) The lactam flange body 8.1 obtained in the above operation was dissolved in dimethyl sulfoxide and cumene, which were also recovered in the above operation, and the same operation as the previous time was repeated. From the upper layer, lactam 3. 0 females (yield 2
3.2%) was obtained.

Therefore, the total yield of lactam is Sat. It was 7%.

Example 2 (1st operation) Lactam collar body 5.0 string dimethyl sulfoxide 3.1$
and benzene 53. It was dissolved in thigh g (90.9 mol%), shaken vigorously, allowed to settle, and separated into two layers.

The upper layer was separated and distilled to remove benzene, and then distilled under reduced pressure to obtain 1.7 lactam bodies (yield 55.4%) and 1.8 lactam rust bodies as a residue. On the other hand, the lower layer was distilled to remove dimethyl sulfoxide, and then distilled under reduced pressure to remove lactam rust.
．． I got 3 spots. (Second operation) When 2.21 g of the lactam rust obtained in the above operation was dissolved in dimethyl sulfoxide and benzene, which were also recovered in the above operation, and the same operation as the previous time was repeated, 0.74 g of lactam was obtained from the upper layer. A yield of 23.3% was obtained.

Therefore, the total yield of lactam was 787%. Example 3 (First operation) 5.0 cycles of a lactam mirror was mixed with 3.6 cycles of dimethylformamide and 37 cycles of toluene. It was dissolved in a thin solution (84.0 mol %), shaken vigorously, allowed to settle, and separated into two layers.

The upper layer was separated and distilled to remove toluene, and then distilled under reduced pressure to obtain 1.7 lactams (yield 56.5%) and 1.9 lactam rust bodies as a residue. On the other hand, the lower layer was distilled to remove dimethylformamide, and then distilled under reduced pressure to remove the lactam complex.
．． Got 2nd round. (Second operation) 2.17 g of the lactam complex obtained in the above operation was dissolved in dimethylformamide and Tresso, which were also recovered in the above operation, and the same operation as the previous time was repeated. 77g (
A yield of 24.4%) was obtained.

Therefore, the total yield of lactam was 80.9%. Example 4 (1st operation) A lactam anchor body of 5.0 mm was mixed with a 4.3 mm string of dimethylacetamide and 41 mm of ethylbenzene. The mixture was dissolved in 100% (83.5 mol %), shaken vigorously, and then allowed to stand still to separate into two layers.

The upper layer was separated and distilled to remove ethylbenzene, and then distilled under reduced pressure to obtain 1.8 g of lactam (yield 58.6%) and 1.57 g of lactam rust as a residue. On the other hand, the lower layer was distilled to remove dimethylacetamide, and then distilled under reduced pressure to obtain 0.4 pieces of lactam rust. (Second operation) 2.0 pieces of the lactam body obtained in the above operation were dissolved in dimethylacetamide and ethylbenzene, which were also recovered in the above operation, and the same operation as the previous time was repeated. 7.0 (yield 234%) was obtained.

Therefore, the total yield of lactam was 82.0%. Example 5 (1st operation) 5.03 g of lactam fin body was mixed with 3.6 g of dimethyl sulfoxide.
The key and p-xylene were dissolved in 50.1 g (86.3 mol %), shaken vigorously, and then allowed to stand still to separate into two layers.

The upper layer was separated and distilled to remove p-xylene, and then distilled under reduced pressure to obtain 1.8 g of lactam (yield 57.9%) and 1.85 g of lactam key body as a residue. On the other hand, the lower layer was distilled to remove dimethyl sulfoxide, and then distilled under reduced pressure to obtain 0.2 ml of lactam. (Second operation) The lactam anchor 2.0 purple obtained in the above operation was dissolved in dimethyl sulfoxide and p-xylene, which were also recovered in the above operation, and the same operation as the previous time was repeated. .7 bamboo grass (yield 23.4%) was obtained.

Claims (1)

[Claims] 1. ε-caprolactam obtained in a method for producing ε-caprolactam by subjecting cyclohexanone oxime to Beckman rearrangement in the presence of boron trifluoride or its adduct. A decomposition solvent selected from the group consisting of dimethyl sulfoxide, dimethylformamide, and dimethylacetamide and an extraction solvent selected from the group consisting of benzene and alkylbenzene are added to the boron trifluoride complex, and the liquid is separated into two layers, starting from the upper layer. A method for producing ε-caprolactam, which comprises obtaining ε-caprolactam.