JP2000229940A - Production of highly pure pyrrolidones - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply obtaining an extremely highly pure pyrrolidone or N-alkylpyrrolidone. SOLUTION: This method for producing pyrrolidone or an N-alkylpyrrolidone comprises reacting γ-butyrolactone with ammonia or a primary alkylamine in the presence of water. Therein, the characteristics comprise heating the γ-butyrolactone and the ammonia or the primary alkylamine in the presence of water to obtain the reaction mixture comprising >30 wt.% of water, a γ- hydroxybutylalkylamide, and the pyrrolidone or the N-alkylpyrrolidone, reducing the water content of the reaction mixture to <=30 wt.%, and then heating the water content-reduced reaction mixture in a state containing the ammonia or the primary alkylamine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing pyrrolidone or N
A process for producing alkylpyrrolidone.

[0002]

BACKGROUND ART Pyrrolidones typified by N-methyl-2-pyrrolidone show excellent substance solubility,
It is used as various solvents / solvents, and in recent years, it is also used for electronic and electric applications, for example, cleaning of electric substrates, resist stripping agents, or production of Li batteries. When used in the manufacture of Li batteries, γ remaining in N-methyl-2-pyrrolidone
However, there is a problem that the pH is increased by a basic substance such as monomethylamine generated by decomposition of -hydroxybutylmethylamide. N-methyl-2-pyrrolidone is
Industrially, it is generally produced by reacting γ-butyrolactone with an excess amount of monomethylamine. In this reaction, it is known that N-methyl-2-pyrrolidone can be produced in a high yield in a short time because water is added to the reaction system to increase the reaction rate (Japanese Patent Publication No. 47-21420).
No.). In this method, the reaction of γ-butyrolactone can be completed because an excess amount of monomethylamine is used, and the reaction rate is increased due to the presence of water in the reaction system. However, since a large amount of water is contained, a small amount of the intermediate γ-hydroxybutylmethylamide remains in the product due to equilibrium. Therefore, γ-
Hydroxybutylmethylamide has the disadvantage that it decomposes during purification by distillation to form γ-butyrolactone, which cannot be separated by ordinary distillation, leading to a decrease in the purity of N-methyl-2-pyrrolidone. In addition, a method of removing these by means such as adsorption may be considered, but this is not preferable because it causes an increase in cost.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method for easily obtaining pyrrolidone or N-alkylpyrrolidone of extremely high purity.

[0004]

Means for Solving the Problems The present inventors have conducted various studies to solve the above problems. As a result, if the following method is adopted, pyrrolidone of extremely high purity or N-
The inventors have found that alkylpyrrolidone can be easily obtained, and have completed the present invention. That is, the present invention
(1) a method for producing pyrrolidone or N-alkylpyrrolidone by reacting γ-butyrolactone with ammonia or a primary alkylamine in the presence of water;
By heating butyrolactone and ammonia or a primary alkylamine in the presence of water, more than 30% by weight of water, γ
Obtaining a reaction mixture comprising -hydroxybutylalkylamides and pyrrolidone or N-alkylpyrrolidone, reducing the water content of the reaction mixture to 30% by weight or less,
Next, the method is characterized in that the reaction mixture after the water content is reduced to 30% by weight or less contains ammonia or a primary alkylamine, and the reaction mixture is heated.

Japanese Patent Application Laid-Open No. 6-263725 discloses that N-methyl-2-pyrrolidone containing water is heat-treated at a predetermined temperature and time and then distilled to distill N-methyl-2-pyrrolidone. A method for purifying the featured N-methyl-2-pyrrolidone is disclosed. This method is a method for purifying water-containing N-methyl-2-pyrrolidone produced by reacting γ-butyrolactone with an excess amount of monomethylamine in the presence of water. In the method, a substance contained in N-methyl-2-pyrrolidone containing water obtained by the above reaction, which is considered to cause coloration with time, is subjected to heat treatment in advance before distillation purification to decompose or polymerize,
Then, in the distillation purification process, the obtained decomposed product such as monomethylamine or a polymer is removed. In this way, it is intended to remove as much as possible substances which are considered to cause coloring with time. However, due to this heat treatment, N
Γ-hydroxybutylalkylamides, which are intermediate products contained in -methyl-2-pyrrolidone, are decomposed to give γ
-Produces butyrolactone. Such γ-
Butyrolactone is very difficult to separate from N-methyl-2-pyrrolidone by distillation. Therefore, in order to obtain N-methyl-2-pyrrolidone of extremely high purity, it was necessary to further rely on means such as adsorption.

The present inventors have developed an intermediate γ-butyrolactone while preventing the formation of γ-butyrolactone, which is extremely difficult to separate by distillation from pyrrolidone or N-alkylpyrrolidone such as N-methyl-2-pyrrolidone. The inventors of the present invention diligently studied how to convert hydroxybutylalkylamides, for example, γ-hydroxybutylmethylamide, to the final products, pyrrolidone or N-alkylpyrrolidone. As a result, more than 30% by weight of water, γ-hydroxybutylalkylamides, and pyrrolidone or N-alkylpyrrolidone obtained by heating γ-butyrolactone and ammonia or a primary alkylamine in the presence of water For example, reducing the water content of the reaction mixture containing N-methyl-2-pyrrolidone to 30% by weight or less and heating the reaction mixture with ammonia or a primary alkylamine, such as monomethylamine, Included γ-hydroxybutylalkylamides, such as γ
-Hydroxybutylmethylamide can suppress the decomposition to γ-butyrolactone,
Hydroxybutylalkylamides are converted to pyrrolidone or N
-Pyrrolidone or N-alkylpyrrolidone, especially N-methyl-2-pyrrolidone, which can be converted to -alkylpyrrolidone and has very high purity.

In a preferred embodiment, (2) the water content of the reaction mixture containing more than 30% by weight of water, γ-hydroxybutylalkylamides and pyrrolidone or N-alkylpyrrolidone is reduced to 1 to 25% by weight, The method according to (1) above, wherein (3) the water content of the reaction mixture containing more than 30% by weight of water, γ-hydroxybutylalkylamides, and pyrrolidone or N-alkylpyrrolidone is 1 to 20% by weight. (4) The method of (1), wherein the reaction mixture after reducing the water content to 30% by weight or less further contains γ-butyrolactone. The method according to any one,
(5) The amount of ammonia or primary alkylamine during heating of the reaction mixture after reducing the water content to 30% by weight or less is determined by the amount of γ-hydroxybutylalkylamides and γ-butyrolactone contained in the reaction mixture. (1) to (1) which are 1 to 10,000 in molar ratio with respect to the total amount of
The method according to any one of (4),

(6) The amount of ammonia or primary alkylamine when the reaction mixture is heated after the water content is reduced to 30% by weight or less is determined by the amount of γ-hydroxybutylalkylamides and (7) The method according to any one of the above (1) to (4), wherein the molar ratio to the total amount of γ-butyrolactone is from 10 to 5,000.
The amount of ammonia or primary alkylamine when heating the reaction mixture after reducing the water content to 30% by weight or less is the total amount of γ-hydroxybutylalkylamides and γ-butyrolactone contained in the reaction mixture. The method according to any one of the above (1) to (4), wherein the molar ratio is 50 to 3,000, and (8) the heating temperature of the reaction mixture after reducing the water content to 30% by weight or less. But 200 ~
(9) The method according to any one of (1) to (7) above, wherein the primary alkylamine is monomethylamine. (10) The method according to any one of (1) to (9) above, wherein the N-alkylpyrrolidone is N-methyl-2-pyrrolidone.

(11) The method according to any one of the above (1) to (10), wherein the γ-hydroxybutylalkylamide is γ-hydroxybutylmethylamide,
2) a reaction mixture comprising heating γ-butyrolactone and ammonia or a primary alkylamine in the presence of water to contain more than 30% by weight of water, γ-hydroxybutylalkylamides, and pyrrolidone or N-alkylpyrrolidone Is obtained by heating γ-butyrolactone and an excess amount of monomethylamine in the presence of water to give more than 30% by weight of water, γ-hydroxybutylmethylamide and N
A process for producing a reaction mixture comprising -methyl-2-pyrrolidone, wherein the molar ratio of monomethylamine to γ-butyrolactone is from 1.03 to 1.50,
Any one of the above (1) to (11), wherein water is present in the reaction system in an amount of 1.0 to 2.9 times the molar amount of γ-butyrolactone and the reaction is carried out at a temperature of 250 to 300 ° C. Can be mentioned.

[0010]

DETAILED DESCRIPTION OF THE INVENTION In the process of the present invention, a reaction mixture containing more than 30% by weight of water, .gamma.-hydroxybutylalkylamides, and pyrrolidone or N-alkylpyrrolidone is treated with .gamma.-butyrolactone and ammonia or primary It is obtained by heating an alkylamine with water in the presence of water. The reaction mixture may further contain unreacted γ-butyrolactone. Preferably, a reaction mixture comprising more than 30% by weight of water, γ-hydroxybutylmethylamide and N-methyl-2-pyrrolidone is obtained by heating γ-butyrolactone and monomethylamine in the presence of water. In the above reaction, it is preferable to react γ-butyrolactone with an excess amount of ammonia or a primary alkylamine, preferably monomethylamine, to obtain a reaction mixture substantially free of γ-butyrolactone. In the reaction mixture, the water content is preferably more than 30% by weight and not more than 60% by weight, and the content of γ-hydroxybutylalkylamides, preferably γ-hydroxybutylmethylamide, is preferably 0.1%. 001
The content of γ-butyrolactone, which is optionally contained, is preferably 10 mol% or less.

The above-mentioned γ-butyrolactone and ammonia or primary alkylamine are heated in the presence of water to give 3
There is no particular limitation on the method for obtaining a reaction mixture containing more than 0% by weight of water, γ-hydroxybutylalkylamides, and pyrrolidone or N-alkylpyrrolidone. For example,
The method described in JP-B-47-21420 can be used. Preferably the method described in JP-A-10-158238,
That is, γ-butyrolactone is reacted with an excess amount of monomethylamine to produce N-methyl-2-pyrrolidone, and the molar ratio of monomethylamine to γ-butyrolactone is 1.03 to 1.50; In the reaction system, a method can be used in which water is present in an amount of 1.0 to 2.9 times the molar amount of γ-butyrolactone and the reaction is carried out at a temperature of 250 to 300 ° C.

In the process according to the invention, more than 30% by weight of water, γ-hydroxybutylalkylamides, preferably γ-hydroxybutylmethylamide, optionally γ-butyrolactone, obtained as described above, and The upper limit of the water content of the reaction mixture containing pyrrolidone or N-alkylpyrrolidone, preferably N-methyl-2-pyrrolidone, is 30% by weight, preferably 25% by weight, particularly preferably 20% by weight and lower limit thereof. But preferably 1
% By weight, particularly preferably 1.5% by weight. If the upper limit is exceeded, the purity of purified pyrrolidone or N-alkylpyrrolidone, preferably N-methyl-2-pyrrolidone, cannot be increased. There is no particular limitation on the method for controlling the water content in the above range. For example, 30% by weight obtained as described above
More than water, γ-hydroxybutylalkylamides,
Optionally γ-butyrolactone, and pyrrolidone or N-
Distilling or flushing the reaction mixture containing alkylpyrrolidone under mild conditions so that γ-hydroxybutylalkylamides do not decompose, or removing water, or adsorbing water with adsorbents such as molecular sieves and dehydrating agents A removal method and the like can be mentioned.

After reducing the water content to below 30% by weight, the reaction mixture is then heated with ammonia or a primary alkylamine. Preferably, 30% by weight
The following reaction mixture containing water, γ-hydroxybutylmethylamide, optionally γ-butyrolactone, and N-methyl-2-pyrrolidone is heated with monomethylamine. Here, the amount of ammonia or primary alkylamine, preferably monomethylamine, is relative to the total amount of γ-hydroxybutylalkylamides, preferably γ-hydroxybutylmethylamide, and optionally γ-butyrolactone. In the ratio, the upper limit is preferably 10,000 mol, more preferably 5,000 mol, particularly preferably 3,000 mol, and the lower limit is preferably 1 mol, more preferably 10 mol, particularly preferably 100 mol. . Below the lower limit, the production of γ-butyrolactone due to the decomposition of γ-hydroxybutylalkylamides, such as γ-hydroxybutylmethylamide, cannot be suppressed, and when γ-butyrolactone is present, γ-butyrolactone is present. Cannot be converted to γ-hydroxybutylalkylamides, preferably γ-hydroxybutylmethylamide, and therefore the purity of the pyrrolidone or N-alkylpyrrolidone, preferably N-methyl-2-pyrrolidone, after purification is extremely high. Can't be expensive. Exceeding the above upper limit is not preferable because the effect is not increased and the cost is increased.

The temperature at which the reaction mixture after reducing the water content to 30% by weight or less while containing ammonia or a primary alkylamine, preferably monomethylamine, has an upper limit of preferably 320 ° C., more preferably 320 ° C. Is 300
° C, and the lower limit is preferably 200 ° C, more preferably 250 ° C. Above the upper limit, by-products increase, and below the lower limit, pyrrolidone or N-alkylpyrrolidone, such as N-alkyl
The conversion to methyl-2-pyrrolidone is insufficient, and the purity of purified pyrrolidone or N-alkylpyrrolidone cannot be extremely high. The pressure at the time of the heating is adjusted to a range in which the heating can be performed under the liquid phase. Preferably it is 10 to 150 kg / cm ² .

The pyrrolidone or N-alkylpyrrolidone obtained by the process according to the invention, preferably N-methyl-2
-Pyrrolidone is substantially free of γ-hydroxybutylalkylamides, preferably γ-hydroxybutylmethylamide and γ-butyrolactone. Thus, very high purity pyrrolidone or N-alkylpyrrolidone, preferably N-methyl-2-pyrrolidone, can be obtained by distillation. Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0016]

【Example】

Example 1 31.000 kg / hour of γ-butyrolactone and a 40% by weight aqueous monomethylamine solution (γ-butyrolactone)
Butyrolactone: monomethylamine: water = 1.0: 1.
(A molar ratio of 1: 2.9). In the reactor, the reaction was carried out at 280 ° C. for 5 hours under the liquid phase. The amount of each component in the effluent from the reactor was 0.005 kg / hour of γ-hydroxybutylmethylamide, N
35.692 kg / hr of water, 25.088 kg / hr of water and 1.21 of monomethylamine
It was 5 kg / hour. Here, the water content of the effluent was about 40.5% by weight. Also, γ-butyrolactone was not detected. The reactor effluent was fed to a distillation column, 15.088 kg / hr of water and 1.215 kg / hr of monomethylamine were withdrawn from the top of the column, and 0.005 k of γ-hydroxybutylmethylamide was removed from the bottom of the column.
g / h, N-methyl-2-pyrrolidone was 35.692
kg / h and water were withdrawn at 10.000 kg / h. Next, the entire amount of the liquid extracted from the bottom of the column and 3.037 kg / hour of a 40% by weight aqueous solution of monomethylamine were supplied to a heater. Here, the liquid extracted from the bottom of the column and the aqueous solution of 40% by weight of monomethylamine were supplied to the heater after being sufficiently mixed in the pipe. After the addition of the monomethylamine aqueous solution, the amount of each component in the supply liquid to the heater is γ
-Hydroxybutylmethylamide 0.005 kg / hr, N-methyl-2-pyrrolidone 35.692 kg / hr, water 11.822 kg / hr and monomethylamine 1.215 kg / hr. The water content of the feed was about 24.3% by weight. The amount of monomethylamine present in the heater was about 910 in molar ratio to the total amount of γ-hydroxybutylmethylamide and γ-butyrolactone.

In the heater, heating was performed at 280 ° C. for 8 hours in the liquid phase. The amount of each component in the effluent from the heater is γ
-Hydroxybutylmethylamide 0.0024 kg / hour, N-methyl-2-pyrrolidone 35.694 kg / hour, water 11.823 kg / hour and monomethylamine 1.215 kg / hour. γ-butyrolactone was not detected. The effluent is distilled to give water 11.82
3 kg / hour and 1.215 kg / hour of monomethylamine and 0.0024 of γ-hydroxybutylmethylamide
kg / h and N-methyl-2-pyrrolidone 35.69
4 kg / h. About 52% by weight of γ-hydroxybutylmethylamide contained in the reactor effluent
Was removed, and the purity of the obtained N-methyl-2-pyrrolidone was about 99.993% by weight.

[0018]

Example 2 After the reaction was carried out under the same conditions as in Example 1, the effluent was fed to a distillation column, and 24.088 water was fed from the top of the column.
kg / hour and monomethylamine were withdrawn at 1.215 kg / hour, and from the bottom of the column 0.005 kg / hour of γ-hydroxybutylmethylamide, 35.692 kg / hour of N-methyl-2-pyrrolidone and 1. 000k
g / h. Then, as in Example 1, 3.037 kg / of a 40% by weight aqueous solution of monomethylamine was used.
Add time and feed to heater. After the addition of the aqueous monomethylamine solution, the amount of each component in the supply liquid to the heater was 0.005 kg / hour of γ-hydroxybutylmethylamide, N
35.692 kg / h of -methyl-2-pyrrolidone, 2.822 kg / h of water and 1.215 of monomethylamine
kg / hr. The water content of the feed is about 7.1
% By weight. In addition, the amount of monomethylamine present in the heater was determined by comparing γ-hydroxybutylmethylamide and γ-
The molar ratio to the total amount of butyrolactone was about 910.

In the heater, heating was performed at 280 ° C. for 8 hours in the liquid phase. The amount of each component in the effluent from the heater is γ
-Hydroxybutylmethylamide 0.0004 kg / h, N-methyl-2-pyrrolidone 35.696 kg / h, water 2.823 kg / h and monomethylamine 1.
It was 215 kg / hour. γ-butyrolactone was not detected. The effluent was distilled under the same conditions as in Example 1 to obtain 2.823 kg / h of water and 1.
215 kg / hour and 0.0004 kg / hour of γ-hydroxybutylmethylamide and 35.696 kg / hour of N-methyl-2-pyrrolidone. About 92% by weight of γ-hydroxybutylmethylamide contained in the reactor effluent was removed, and the resulting N-methyl-2-
The purity of pyrrolidone was about 99.999% by weight.

[0020]

Example 3 Example 3 was carried out in the same manner as in Example 1 except that the heating temperature in the heater was 250 ° C. The amount of each component in the effluent from the heater was 0.
0016 kg / hour, N-methyl-2-pyrrolidone 3
5.695 kg / h, water 11.823 kg / h and monomethylamine 1.215 kg / h. γ-
Butyrolactone was not detected. The effluent was distilled under the same conditions as in Example 1 to obtain 11.823 kg / hr of water and 1.215 kg / hr of monomethylamine, 0.0016 kg / hr of γ-hydroxybutylmethylamide and N-methyl-2-pyrrolidone It separated to 35.695 kg / hour. About 68% by weight of γ-hydroxybutylmethylamide contained in the reactor effluent was removed, and the purity of the obtained N-methyl-2-pyrrolidone was about 99.9.
It was 96% by weight.

[0021]

Example 4 Example 1 was repeated except that 2.025 kg / hour of a 10% by weight aqueous solution of monomethylamine was supplied to the heater.
The same was performed. After the addition of the monomethylamine aqueous solution, the amount of each component in the liquid supplied to the heater was 0.005 kg / hour of γ-hydroxybutylmethylamide and N-methyl-2
35,692 kg / hour of pyrrolidone, water 11.822
kg / h and monomethylamine 0.202 kg / h. The water content of the feed was about 24.8% by weight. The amount of monomethylamine present in the heater was about 150 in molar ratio to the total amount of γ-hydroxybutylmethylamide and γ-butyrolactone.
In the heater, heating was performed at 280 ° C. for 8 hours in the liquid phase.
The amount of each component in the effluent from the heater was 0.0023 kg / hour of γ-hydroxybutylmethylamide, 35.694 kg / hour of N-methyl-2-pyrrolidone,
1.823 kg / h and monomethylamine 0.202
kg / hr. γ-butyrolactone was not detected.

The effluent was distilled under the same conditions as in Example 1 to obtain 11.823 kg / hour of water and 0.202 kg / hour of monomethylamine, 0.0023 kg / hour of γ-hydroxybutylmethylamide and N-methyl- It separated to 35.694 kg / hour of 2-pyrrolidone. About 54% by weight of γ-hydroxybutylmethylamide contained in the reactor effluent was removed, and the resulting N-methyl-
The purity of 2-pyrrolidone was about 99.994% by weight.

[0023]

COMPARATIVE EXAMPLE 1 The same operation as in Example 1 was carried out except that the effluent from the reactor was not distilled, but was directly supplied to a heater and a 40% by weight aqueous solution of monomethylamine was not supplied. The water content of the feed to the heater is about 40.5
% By weight. In addition, the amount of monomethylamine present in the heater was determined to be γ-hydroxybutylmethylamide and γ-hydroxybutylmethylamide.
The molar ratio to the total amount of butyrolactone was about 910. The amount of each component in the effluent from the heater was 0.005 kg / hour of γ-hydroxybutylmethylamide, N-
35.692 kg / h of methyl-2-pyrrolidone, water 2
5.088 kg / h and monomethylamine 1.215
kg / hr.

The effluent was distilled under the same conditions as in Example 1 to obtain 25.088 kg / hour of water and 1.215 kg / hour of monomethylamine, 0.005 kg / hour of γ-hydroxybutylmethylamide and N-methyl- 2-pyrrolidone was separated to 35.692 kg / hour. Γ-hydroxybutylmethylamide contained in the reactor effluent could not be removed at all, and the resulting N-methyl-
The purity of 2-pyrrolidone was as low as 99.986% by weight.

[0025]

Comparative Example 2 The same operation was performed as in Comparative Example 1, except that the heating time in the heater was changed to 15 hours. The amounts of each component in the effluent from the heater were the same as in Comparative Example 1.

[0026]

Comparative Example 3 The same operation as in Comparative Example 1 was carried out except that the heating temperature in the heater was changed to 250 ° C. The amount of each component in the effluent from the heater was 0.004 kg / hour of γ-hydroxybutylmethylamide, N-methyl-2-pyrrolidone 3
5.693 kg / hr, water 25.088 kg / hr and monomethylamine 1.215 kg / hr. The effluent was distilled under the same conditions as in Example 1 to obtain 25.088 water.
kg / hour and 1.215 kg / hour of monomethylamine and 0.004 kg of γ-hydroxybutylmethylamide
/ Hour and N-methyl-2-pyrrolidone 35.693k
g / h. Only about 20% by weight of γ-hydroxybutylmethylamide contained in the reactor effluent could be removed, and the purity of the obtained N-methyl-2-pyrrolidone was as low as 99.989% by weight. .

[0027]

Comparative Example 4 The operation was performed in the same manner as in Example 1 except that a 40% by weight aqueous solution of monomethylamine was not supplied to the heater. The amount of each component in the effluent from the heater was 0.013 kg / hour of γ-butyrolactone, 0.002 kg / hour of γ-hydroxybutylmethylamide, N-methyl-2-
35.680 kg of pyrrolidone / hour, 9.998 kg of water
/ H and monomethylamine 0.0047 kg / h. The effluent was distilled under the same conditions as in Example 1 to obtain 9.998 kg / h of water and 0.004 of monomethylamine.
7 kg / hour and 0.013 kg / γ-butyrolactone
Time, γ-hydroxybutylmethylamide 0.002k
g / hr and N-methyl-2-pyrrolidone 35.680
kg / h. The purity of the obtained N-methyl-2-pyrrolidone was very low at about 99.958% by weight.

The N-methyl-2-pyrrolidone prepared by the method of the present invention in Examples 1 to 4 was 99.9%.
It had a very high purity of 90% by weight or more. Example 2 was prepared by lowering the water content in the reactor effluent than in Example 1 and heating in the presence of monomethylamine. The lower the water content, the higher the purity of N
It was found that -methyl-2-pyrrolidone was obtained.
Example 3 is different from Example 1 in that the heating temperature in the presence of monomethylamine was further reduced. N-methyl-
It was found that the purity of 2-pyrrolidone was higher.
In Example 4, heating was performed with a smaller amount of monomethylamine than in Example 1. Very high purity N-methyl-2-pyrrolidone, which is almost the same as in Example 1, was obtained.

On the other hand, Comparative Example 1 was obtained by heating in the presence of monomethylamine without reducing the water content in the reactor effluent obtained in the same manner as in Example 1 to the range of the present invention. . gamma-Hydroxybutylmethylamide could not be removed and the purity of N-methyl-2-pyrrolidone could not be made very high. Comparative Example 2 is Comparative Example 1
As in the above, the heating time in the presence of monomethylamine was made longer without reducing the water content in the reactor effluent to the range of the present invention. The result was similar to that of Comparative Example 1. In Comparative Example 3, as in Comparative Example 1, the heating temperature in the presence of monomethylamine was lowered without reducing the water content in the reactor effluent to the range of the present invention. Although some removal of γ-hydroxybutylmethylamide was possible, the purity of N-methyl-2-pyrrolidone could not be significantly increased. Comparative Example 4
As described in JP-A-6-263725, heating in a heater is performed in the absence of monomethylamine. It was found that γ-hydroxybutylmethylamide and N-methyl-2-pyrrolidone decomposed to form γ-butyrolactone, which significantly reduced the purity of N-methyl-2-pyrrolidone. In all of Comparative Examples 1 to 4, the purity of the produced N-methyl-2-pyrrolidone was 99.990.
% By weight.

[0030]

The present invention provides a method for conveniently obtaining pyrrolidone or N-alkylpyrrolidone of extremely high purity.

Claims (6)

[Claims] A method for producing pyrrolidone or N-alkylpyrrolidone by reacting γ-butyrolactone with ammonia or a primary alkylamine in the presence of water, comprising the steps of: Is heated in the presence of water to obtain a reaction mixture containing more than 30% by weight of water, γ-hydroxybutylalkylamides and pyrrolidone or N-alkylpyrrolidone, and the water content of the reaction mixture is reduced to 30%. A method comprising reducing the water content to less than 30% by weight, and then heating the reaction mixture with the ammonia or primary alkylamine after reducing the water content to less than 30% by weight. 2. The reaction mixture containing more than 30% by weight of water, .gamma.-hydroxybutylalkylamides and pyrrolidone or N-alkylpyrrolidone has a water content of from 1 to 25.
2. The method of claim 1, wherein the weight is reduced to% by weight and then heating. 3. The reaction mixture after reducing the water content to 30% by weight or less, further comprising γ-butyrolactone.
Or the method of 2. 4. The amount of ammonia or primary alkylamine when the reaction mixture is heated after the water content is reduced to 30% by weight or less, when the amount of γ-hydroxybutylalkylamides and γ In a molar ratio of 1 to 10,000 with respect to the total amount of -butyrolactone.
The method according to any one of 1 to 3. 5. The process according to claim 1, wherein the heating temperature of the reaction mixture after reducing the water content to 30% by weight or less is 200-320 ° C. 6. The method according to claim 1, wherein the primary alkylamine is monomethylamine.