JP2652280B2 - Preparation of amides by liquid phase rearrangement of oximes. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an amide by liquid phase rearrangement of an oxime.

[0002]

BACKGROUND OF THE INVENTION The rearrangement of oximes to amides is known as the Beckmann rearrangement. For example, in the production of ε-caprolactam by rearrangement of cyclohexanone oxime, fuming sulfuric acid is used industrially as a catalyst. However, in the method using fuming sulfuric acid, in addition to the essential drawback that a large amount of ammonium sulfate is produced as a by-product, there are many problems in the process such as corrosion of the apparatus, and the development of an efficient rearrangement catalyst has been desired.

[0003] For example, solid oxide catalysts in which boron oxide is supported on silica, alumina or titania, and zeolite catalysts have been proposed. When these solid catalysts are used for a rearrangement reaction, high-temperature gas phase reaction conditions must be used. Since it is necessary to employ the compound, the yield of ε-caprolactam decreases, the catalyst deteriorates, and the energy cost increases.

[0004] On the other hand, there have been known several methods for obtaining ε-caprolactam by rearranging cyclohexanone oxime under relatively mild reaction conditions such as a liquid phase reaction. One is N,
This method uses an ion pair (Vilsmeier complex) obtained by the reaction between N-dimethylformamide and chlorosulfonic acid as a catalyst (MAKira and YMShaker, Egypt. J. Chem.,
16, 551 (1973)). However, this method is described as requiring a catalyst in an equimolar amount with the oxime since the formed lactam and the catalyst form a 1: 1 complex, which is not economical.

The inventor has previously reported a liquid phase Beckmann rearrangement reaction using an alkylating agent obtained from an epoxy compound and a strong acid (such as boron trifluoride / etherate) and a catalyst comprising N, N-dialkylformamide ( Y.Izumi, C
hemistry Letters, pp.2171 (1990)). Although this method discloses an excellent new rearrangement method, it is not necessarily industrially satisfactory in terms of economy and operability, such as requiring an epoxy compound and a strong acid for the alkylating agent used as a component of the rearrangement catalyst. You don't get it.

Japanese Patent Application Laid-Open No. 62-149665 discloses a method for producing ε-caprolactam by rearranging cyclohexanone oxime in a heptane solvent using a phosphoric acid catalyst. On the other hand, it is necessary to use a large amount of phosphoric acid as much as about twice as much as the catalyst. Therefore, the reaction is neutralized with ammonia, and the phosphoric acid catalyst is recovered and reused through a complicated process.

[0007]

SUMMARY OF THE INVENTION The present invention provides an amide which is free from the above-mentioned problems by rearranging an oxime at a mild reaction temperature under a liquid phase condition and in the presence of a small amount of a substoichiometric catalyst. An object of the present invention is to provide a method for producing the same.

The present inventors have made intensive studies on catalysts for converting an oxime to an amide. As a result, at least one compound selected from N, N-dialkylamides, N-alkyl cyclic amides and dialkyl sulfoxides has been developed. When an oxime rearrangement reaction is performed in the presence of phosphorus pentoxide,
The present inventors have found that the reaction is remarkably accelerated, and have reached the present invention.

[0009]

Means for Solving the Problems That is, the present invention provides N, N-
A method for producing an amide by liquid phase rearrangement of an oxime, which comprises reacting at least one compound selected from the group consisting of a dialkylamide, an N-alkyl cyclic amide and a dialkylsulfoxide in the presence of phosphorus pentoxide.

As the N, N-dialkylamide used in the present invention, formamide having the same or different alkyl group having 1 to 6 carbon atoms on the nitrogen atom or 1 to 6 carbon atoms is used.
And specifically, N, N-dimethylformamide, N, N-diethylformamide, N, N-di-i
-Propylformamide, N, N-dibutylformamide,
N, N-dihexylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-di-i-propylacetamide, N, N-dimethylpropionamide, N, N-dimethylbutyamide, N, N-dimethylcaproic acid amide and the like.

As the N-alkyl cyclic amide, one having 1 carbon atom
A cyclic amide having 4 to 6 carbon atoms on a nitrogen atom, specifically, N-methylpyrrolidone,
N-methylpiperidone and the like can be mentioned.

The dialkyl sulfoxide is a sulfoxide having the same or different alkyl group having 1 to 6 carbon atoms, and specific examples include dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, dihexyl sulfoxide and the like.

Since the activity of this reaction is inhibited by water, the above compound is used after drying. The amount of phosphorus pentoxide used is not particularly limited, but is usually in the range of about 0.1 to 50 mol%, preferably about 1 to 20 mol% of the oxime.

The method of the present invention can be preferably applied to the rearrangement of ketone oximes to amides. Specific oximes include cyclohexanone oxime, cyclopentanone oxime, cyclododecanone oxime, 2-butanone oxime, acetophenone oxime, benzophenone oxime and the like. Among them, particularly, cyclohexanone oxime can be preferably applied.

In the present invention, phosphorus pentoxide and oxime are
N, N-dialkyl amide, N- alkyl cyclic amide and a rearrangement reaction proceeds by simply mixing with at least one compound selected from the group consisting of dialkyl sulfoxide,
The corresponding amide is obtained. As an example of the order of addition, after adding phosphorus pentoxide to at least one compound selected from the group consisting of N, N-dialkylamide, N-alkyl cyclic amide and dialkyl sulfoxide, heating to a predetermined reaction temperature Then, a method of dropping and reacting an oxime solution and the like can be mentioned. The reaction temperature is usually about 20 to 200
° C, preferably about 30-150 ° C. After the reaction,
Add a small amount of alkali to degrade the catalytic activity. The reaction product can be separated, purified and obtained from the reaction solution by ordinary means such as distillation.

[0016]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 A 200 ml round bottom flask was purged with nitrogen and dried with N, N-
45 ml of dimethylformamide and 0.35 g of phosphorus pentoxide
(2.5 mmol) was added and heated to 60 ° C. Then 8.0 g of cyclohexanone oxime (70.7 mmol
A solution of l) dissolved in 45 ml of N, N-dimethylformamide was added dropwise at 60 ° C. over 60 minutes to react. After completion of the reaction, as a result of analysis by gas chromatography, the conversion of cyclohexanone oxime was 52.9%, and the yield of ε-caprolactam was 48.1% (selectivity was 91.0%). The catalyst turnover (TON) of the formed ε-caprolactam based on phosphorus pentoxide is 13.8 (mol / mo).
l).

Examples 2 to 4 The reaction temperature in Example 1 was set to 80 ° C., 100 ° C., and 120 ° C.
The reaction was carried out in the same manner as in Example 1 except that the temperature was changed to ° C. Table 1 shows the obtained results.

[0019]

Example 5 A 200 ml round bottom flask was purged with nitrogen and dried with N, N-
75 ml of dimethylformamide and 0.70 g of phosphorus pentoxide
(5.0 mmol) was added and heated to 95 ° C. Then 8.0 g of cyclohexanone oxime (70.7 mmol
A solution of l) dissolved in N, N-dimethylformamide (75 ml) was added dropwise at 95 ° C. over 60 minutes to react. After completion of the reaction, as a result of analysis by gas chromatography, the conversion of cyclohexanone oxime was 100%, and the yield of ε-caprolactam was 92.1% (selectivity was 92.1%). The catalyst turnover of the formed ε-caprolactam based on phosphorus pentoxide was 13.0 (mol / mol).

Examples 6 to 10 The 200 ml round-bottomed flask was purged with nitrogen, and the results are shown in Table 2.
23 ml each of N, N-dialkylamide, N-alkyl cyclic amide or dialkyl sulfoxide and phosphorus pentoxide 0.3
5 g (2.5 mmol) was added and heated to 95 ° C.
Next, 4.0 g of cyclohexanone oxime (35.4 mm
ol) was dissolved in 22 ml of each N, N-dialkylamide-based solvent at 95 ° C. over 60 minutes and reacted. After completion of the reaction, the results of the analysis by gas chromatography are shown in Table 2.
It was shown to.

[0022]

Examples 11 to 13 A 200 ml round-bottomed flask was purged with nitrogen and dried to form N, N-
23 ml of dimethylformamide and 0.18 g of phosphorus pentoxide
(1.25 mmol) was added and heated to 120 ° C.
Next, 35.5 mmol of various ketone oximes shown in Table 3
l was dissolved in 22 ml of N, N-dimethylformamide at 120 ° C. over 30 minutes to react. After the completion of the reaction, the results of analysis by gas chromatography are shown in Table 3.

[0024]

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kosaburo Nomura 5-1 Sokai-cho, Niihama-shi, Ehime Prefecture Sumitomo Chemical Industries, Ltd.

Claims (4)

(57) [Claims] 1. A liquid phase of an oxime, which is reacted in the presence of at least one compound selected from the group consisting of N, N-dialkylamide, N-alkyl cyclic amide and dialkylsulfoxide and phosphorus pentoxide. Method for producing amide by rearrangement. 2. The method of claim 2, wherein the N, N-dialkylamide is N, N-dimethylformamide, N, N-diethylformamide, N, N-di-i-
Propylformamide, N, N-dibutylformamide, N,
N-dihexylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-di-i-propylacetamide, N, N-dimethylpropionamide, N, N-dimethylbutyamide or N, N- 2. The process for producing an amide according to claim 1, wherein the amide is dimethylcaproic amide. 3. The method for producing an amide according to claim 1, wherein the N-alkyl cyclic amide is N-methylpyrrolidone or N-methylpiperidone. 4. The process for producing an amide according to claim 1, wherein the dialkyl sulfoxide is dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide or dihexyl sulfoxide.