JP2001354647A - N-methyl-2-pyrrolidone composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an N-methyl-2-pyrrolidone composition having good hue. SOLUTION: An N-methyl-2-pyrrolidone composition is produced by reacting a mixture of ammonia, monomethylamine, dimethylamine and trimethylamine having an absorbance of <=1.0 at 270 nm and/or <=0.5 at 280 nm measured by using a 10 mm cell with a γ-butyrolactone mixture under at least one of the following conditions: (a) the distillation purification process is carried out by setting the contents of each metal component in the distillation column 3 and the packing material of the column within specific ranges, (b) the γ- butyrolactone mixture used as a raw material does not contain impurities having a UV absorption higher than the UV spectrum absorption of pure γ- butyrolactone and (c) the number of compounds other than γ-butyrolactone and having a concentration of >=10 ppm is restricted below a specific level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an N-methyl-2-pyrrolidone composition and a method for producing the same.
The N-methyl-2-pyrrolidone composition itself or N-methyl-2-pyrrolidone having a small amount and kind of various impurities that deteriorate the hue and other quality when used as a solvent or other purposes.
The present invention relates to a methyl-2-pyrrolidone composition and a method for producing the same.

[0002] N-methyl-2-pyrrolidone is used as a solvent in various industrial processes, for example, a metal detergent, a solvent for a functional polymer and the like.

[0003]

2. Description of the Related Art As an industrial production method of pyrrolidones, there are known:
For example, a method is known in which γ-butyrolactone is reacted with ammonia or an amine (hereinafter, these may be collectively referred to as “amines”), and a reaction product is distilled to recover pyrrolidones. As methods for reducing the coloring of pyrrolidones, conventionally, a method of adding water at the time of distillation (Japanese Patent Publication No. 46-32263), a method of adding an oxidizing agent (Japanese Patent Publication No. 47-22225), or a method of distillation method ( JP-A-6-228088, JP-A-6-228088
Japanese Patent Application Laid-Open Nos. 228089 and 6-263725) have been proposed. However, in each case, the effect of reducing coloring is not sufficient, and pyrrolidones having good hue have not been obtained.

Further, when pyrrolidones are used as a solvent or the like, the solute or impurities contained in the solute and impurities contained in the pyrrolidone act to cause strong coloring in some cases. On the other hand, for example, a method has been proposed in which a product pyrrolidone is treated with an adsorption column or the like to remove coloring substances such as ionic substances (Japanese Patent Application Laid-Open No. H10-310795). This is not an industrially advantageous method for simultaneously reducing the types.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an N-methyl-2-pyrrolidone composition having a good hue and to produce it industrially advantageously.

[0006]

The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that an N-methyl-2-pyrrolidone composition having an absorbance at a specific wavelength of less than a certain level has a good hue. And found that it did not exhibit strong coloring when used as a solvent.

In the production of N-methyl-2-pyrrolidone, the distillation column is operated under the condition that the difference in the content of each metal component between the metal surface in contact with the reaction solution and the inside not in contact with the reaction solution is less than a certain value. Production of the N-methyl-2-pyrrolidone composition by using a raw material γ-butyrolactone mixture of good quality and / or a monomethylamine content in the raw material mixed amine of at least a certain level The inventors have found that the invention can be performed, and have completed the invention based on these findings.

That is, a first gist of the present invention is to provide an N-methyl-2-pyrrolidone composition having an absorbance at 270 nm of 1.0 or less and / or an absorbance at 280 nm of 0.5 or less measured using a 10 mm cell. On the thing.

A second gist of the present invention is to provide an N-methyl-2-pyrrolidone composition according to claim 1 by reacting a mixture of ammonia, monomethylamine, dimethylamine and trimethylamine with a γ-butyrolactone mixture. The method for producing, wherein the content of methylamine in the amine mixture is 85% or more and the following four conditions: (a) in a distillation purification step in which the reaction mixture obtained from the reaction step is introduced; Performing distillation while maintaining the content of each metal component of the distillation column and the distillation column packing within 6% as the difference between the surface and the interior in contact with the reaction mixture;
(B) the raw γ-butyrolactone mixture does not contain impurities having a UV absorption higher than the UV spectral absorption of pure γ-butyrolactone; (c) the raw γ-butyrolactone mixture is mixed with polyethylene glycol in a fused silica tube. The number of compounds having a concentration of 10 ppm or more other than γ-butyrolactone detected by gas chromatography analysis using a chemically bonded column is 20 or less, and (d) the γ-butyrolactone raw material is fused. The number of compounds having a concentration of 10 ppm or more other than γ-butyrolactone detected by gas chromatography analysis using a column in which biscyanopropyl-methyl silicon is chemically bonded in a silica gel tube is 15 or less. Satisfies at least one condition selected from The present invention relates to a method for producing N-methyl-2-pyrrolidone.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

N-methyl-2 provided by the present invention
-The pyrrolidone composition has an absorbance at 270 nm measured using a 10 mm cell of 1.0 or less, preferably 0.5 or less, more preferably 0.4 or less, and particularly preferably 0.3 or less.
And / or the absorbance at 280 nm is 0.5 or less, preferably 0.25 or less, more preferably 0.20 or less, particularly preferably 0.15 or less. The N-methyl-2-pyrrolidone composition having such properties has not been provided so far to the knowledge of the present inventors, and has excellent properties such as not exhibiting strong coloring. The absorbance at 270 nm measured using a 10 mm cell exceeds 1.0, and
An N-methyl-2-pyrrolidone composition having an absorbance of 0 nm exceeding 0.5 undesirably exhibits strong coloring when used as a solvent or the like.

The method for producing the N-methyl-2-pyrrolidone composition is not particularly limited, and is, for example, a method usually obtained by reacting γ-butyrolactone with an amine in the presence of water. Yes, but in some cases,
It may be obtained by methylating 2-pyrrolidone.

N-methyl-2 provided by the present invention
-The method for producing the pyrrolidone composition is described below for the case where it is obtained by reacting γ-butyrolactone with an amine in the presence of water.

As the amines, ammonia, C 1
And alkylamines which may have 4 to 4 substituents. Specifically, for example, monomethylamine, monoethylamine, monopropylamine, dimethylamine, diethylamine, dipropylamine, methylethylamine, methylpropylamine, ethylpropylamine, trimethylamine, triethylamine, tripropylamine, dimethylethylan, dimethyl Propylamine, diethylmethylamine, diethylpropylamine,
Examples include dipropylmethylamine, dipropylethylamine, methanolamine, ethanolamine, diethanolamine, triethanolamine, propanolamine, ethylenediamine, and the like. Of these, ammonia, monomethylamine, dimethylamine, trimethylamine or mixtures thereof are preferred. When a mixture of ammonia, monomethylamine, dimethylamine and trimethylamine (mixed amine) is used, the mixing ratio is preferably such that the monomethylamine content is 85% by weight or more.

The raw material γ-butyrolactone mixture used in the present invention (hereinafter simply referred to as “γ-butyrolactone” or “G
BL) are not particularly limited as long as the N-methyl-2-pyrrolidone composition of the present invention is provided, and may be any one or more conditions selected from the following three conditions. Those that satisfy (1) A substance having an absorbance higher than the UV absorbance of γ-butyrolactone itself is not detected in a wavelength range of 180 to 400 nm when analyzed by liquid chromatography (LC) using a UV detector. (2) Analysis by gas chromatography (GC) using a column in which polyethylene glycol is chemically bonded to a tube of fused silica, preferably when analyzed under the following analysis conditions 1, a concentration of 10 ppm or more and 1500 ppm or less. The number of compounds other than γ-butyrolactone detected in the above is 20 or less, preferably 15 or less, more preferably 10 or less, and particularly preferably 5 or less. A specific example of a column in which polyethylene glycol is chemically bonded in a fused silica tube is HR.
-20M (Shinwa Kako) and DB-WAX (J & W)
Corporation), TC-WAX (GL Science Corporation) or PE
G-20M (manufactured by Spelco) and the like. GC analysis condition 1 Measurement device: GC-14 manufactured by Shimadzu Corporation, Column: HR-2
0M (0.53 mmφ, 30 m, df = 1.0 μm),
Column temperature condition: 80 ° C. to 4 ° C./minute, temperature rise to 210 ° C., and maintained at 210 ° C., carrier gas: nitrogen 40 cm /
s (50 ° C.), detector: FID, split ratio 1: 1
2. Inlet temperature 240 ° C, detector temperature 250 ° C, range 10 to the first power, sample injection amount: 0.5 μL, set waveform processing condition: SLOPE = 100 μV / sec MIN.AREA = 50 μV
-Sec. (3) Analysis by gas chromatography (GC) using a column in which biscyanopropyl-methylsilicon (70%) is chemically bonded in a tube of fused silica; More than 15
The number of compounds other than γ-butyrolactone detected at a concentration of 00 ppm or less is 15 or less, preferably 12 or less, more preferably 9 or less, and particularly preferably 6 or less. Specific examples of a column in which biscyanopropyl-methyl silicon (70%) is chemically bonded in a fused silica tube include BPX-70 (SGE) and TC-70 (GL Science). . GC analysis condition 2 Measurement device: GC-17 manufactured by Shimadzu Corporation, Column: BPX-
70 (0.32 mmφ, 60 m, df = 0.25 μm
m), column temperature condition: 80 ° C. to 5 ° C./min, temperature rise to 24
0 ° C., carrier gas: helium 40 cm / s (50
° C), detector: FID, split ratio 1:25, inlet temperature 240 ° C, detector temperature 260 ° C, range 10-1
Squared, sample injection volume: 1.0 μL, set waveform processing condition: SLOP
E = 50 μV / sec MIN.AREA = 0 μV · sec.

The method for producing γ-butyrolactone which satisfies at least one condition selected from the above conditions is not particularly limited, and satisfies the above conditions by combining a known reaction step and a purification step. What is necessary is just to implement. For example, in a reaction system in which there are many types of impurities in the reaction solution, the purification step may be strengthened.

The reaction step may be, for example, a method of hydrogenating maleic anhydride or succinic anhydride using an organometallic complex catalyst, a method of hydrogenating maleic acid or a succinic acid derivative using a solid catalyst, or a method of hydrogenating acetylene from acetylene. A method of dehydrogenation using a solid catalyst via 4-butanediol may be used.

In the step of purifying γ-butyrolactone obtained in the reaction step, distillation or the like is usually used. The distillation conditions are not particularly limited, but generally used distillation conditions, for example, the type of distillation column, the number of columns, the bottom temperature, the top temperature, the pressure, the reflux ratio, the shape of the tray, the number of trays, or the product withdrawal The desired γ-butyrolactone product may be obtained by appropriately setting the position and the like.

The supply amount of amines to γ-butyrolactone is not particularly limited as long as it is equal to or more than the supply amount of γ-butyrolactone.
Preferably it is 1.0 to 3.0 times mol. This allows
Unreacted γ-butyrolactone after the reaction can be reduced as much as possible.

It is not particularly necessary to add water to the reaction system, but if it is supplied usually in an amount of 1 to 8 times the mol of γ-butyrolactone, there is an effect of promoting the reaction.

The reaction temperature may be a temperature usually used for reacting amines with γ-butyrolactone,
For example, usually 150 to 350 ° C., preferably 200 to 3
00 ° C.

The pressure is usually carried out at about the vapor pressure of the raw material mixture at the reaction temperature, and is, for example, usually 0.5 MPa or more, preferably 2 to 10 MPa.
It is.

The reaction time depends on the feed ratio, the flow rate or the reaction temperature of the raw materials, but usually the conversion of γ-butyrolactone is 9%.
The time required for the reaction to be 9% or more may be sufficient, and the residual ratio of the unring-closed intermediate compound in the reaction system is preferably 5% or less, more preferably 1%, based on the pyrrolidones as products.
It is the time required to:

The reaction product obtained in the above reaction step is then introduced into a purification step.

The method for purifying the pyrrolidone from the reaction product may be a known method which is known per se, for example, distillation. The purification method by distillation is usually carried out by removing a low boiling component and a high boiling component by combining a plurality of pressurized, normal or reduced pressure distillation columns.

The type and operating conditions of the distillation column are selected from the viewpoint of the physical properties of the substance to be separated by distillation and the economics of utility costs such as a heat source. Towers, irregularly packed towers, tray towers and the like. The number of stages is usually 1 to 100, preferably 1
The number is from 0 to 90, more preferably from 20 to 80. The reflux ratio is usually in the range of 0.1 to 50, preferably 0.5 to 30, and more preferably 1 to 20.

As the material of the distillation column and the packing of the distillation column,
Industrially, metal products, such as stainless steel, are usually used. Examples of the stainless steel include martensitic, ferritic, and austenitic alloy compositions.Even if any of these are used, the content of each metal component in the distillation column and the distillation column packing is affected by the reaction. It is desirable to carry out the distillation while maintaining the difference between the surface and the interior contacting the mixture within 6%, preferably within 4%, more preferably within 2%. Here, the inside refers to the inside of any material that is not in contact with the reaction mixture,
For example, it may be a surface that appears after the material surface is shaved off by means such as electrolytic polishing, chemical cleaning, high-pressure water cleaning, sandblasting or ultrasonic cleaning. Further, as each metal component, a metal constituting a distillation column or a distillation column packing to be used is targeted, and examples thereof include Fe, Cr, Ni, and Mo. As a method of measuring the content of each metal component of the distillation column and the distillation column packing, for example, measurement at any number of locations by metal surface composition analysis or the like using SEM-EDX, etc., and measurement of the surface and the inside that come into contact with the reaction mixture Just compare the values. In order to purify by distillation so as to satisfy this condition, for example, a method of selecting an appropriate distillation column material or a method of polishing a surface which comes into contact with the reaction mixture by the above-mentioned method is exemplified.

According to the above-mentioned production method, the N-methyl-2-pyrrolidone composition of good quality provided by the present invention can be obtained. A high-quality pyrrolidone composition refers to a composition which has little impurities and does not exhibit strong coloring when used as such or as a solvent or the like. Specifically, for example, it can be confirmed as an N-methyl-2-pyrrolidone composition having a high purity determined by a general analysis method such as GC and LC and / or having a low UV-VIS absorption absorbance up to a low wavelength region.

As described in detail above, the method for producing the N-methyl-2-pyrrolidone composition of the present invention comprises the steps of:
In a reaction step of reacting a mixture of monomethylamine, dimethylamine and trimethylamine (mixed amine) with a mixture of γ-butyrolactone, and a purification step of purifying the reaction mixture by distillation, the content of methylamine in the mixed amine is 85%. And the following four conditions: (a) In the distillation purification step in which the reaction mixture obtained from the reaction step is introduced, the content of each metal component in the distillation column and the distillation column packing is determined by the reaction mixture Performing distillation while maintaining the difference between the contacting surface and the interior within 6%;
(B) the raw γ-butyrolactone mixture does not contain impurities having a UV absorption higher than the UV spectral absorption of pure γ-butyrolactone; (c) the raw γ-butyrolactone mixture is mixed with polyethylene glycol in a fused silica tube. Preferably, 10p other than γ-butyrolactone, which is detected by gas chromatography analysis under the following GC analysis condition 1, using a chemically bonded column.
The number of compounds having a concentration of not less than pm is 20 or less, preferably 15 or less, more preferably 10 or less, particularly preferably 5 or less. GC analysis condition 1: Measuring device: Shimadzu Corporation GC-14,
Column: HR-20M (0.53mmφ, 30m, df
= 1.0 μm), column temperature conditions: 80 ° C. to 4 ° C./min, temperature rise to 210 ° C., maintained at 210 ° C., carrier gas: nitrogen 40 cm / s (50 ° C.), detector: FID, split ratio 1 : 12, inlet temperature 240 ° C, detector temperature 250 ° C, range 10 to the first power, sample injection amount: 0.5μ
L, set waveform processing condition: SLOPE = 100 μV / sec M
IN.AREA = 50 μV · sec (d) The raw material γ-butyrolactone mixture is placed in a tube of fused silica with biscyanopropyl-methyl silicon (7
0%), preferably when analyzed by gas chromatography using the following GC analysis condition 2, a compound other than γ-butyrolactone is detected at a concentration of 10 ppm or more and 1500 ppm or less. The number is 15 or less, preferably 12 or less, more preferably 9 or less, particularly preferably 6 or less. GC analysis condition 2: measuring device: GC-17 manufactured by Shimadzu Corporation
Column: BPX-70 (0.32 mmφ, 60 m, df
= 0.25 μm), column temperature conditions: 80 ° C. to 5 ° C./min, temperature rise to 240 ° C., carrier gas: helium 40 cm
/ S (50 ° C.), detector: FID, split ratio 1: 2
5, inlet temperature 240 ° C, detector temperature 260 ° C, range 10 to the first power, sample injection amount: 1.0 μL, set waveform processing condition: SLOPE = 50 μV / sec MIN.AREA = 0 μV · s
and a method satisfying at least one condition selected from ec. More preferably, the method satisfies the conditions (a), (b), and (c) or (a), (b), and (d) at the same time, and particularly preferably, the method satisfies all the above four conditions at the same time.

[0030]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The γ-butyrolactone (GBL) used in Examples and Comparative Examples was obtained by subjecting succinic anhydride to liquid phase hydrogenation using a Ru-phosphine complex catalyst, followed by distillation and purification. . As a result of three-dimensional LC-UV analysis of this, no compound showing higher UV absorption than GBL itself was detected.

In the LC measurement, a multi-wavelength ultraviolet-visible absorption spectrum was detected using a photodiode array 996 as a detector with an Alliance 2690 apparatus manufactured by Waters. Separation mode was reversed-phase partitioning, and was performed by the gradient elution method of acetonitrile / water system. The analysis conditions were as follows: column: L-column ODS 4.6 φ × 250 mm (Chemical Inspection Association), eluent: acetonitrile / water 5/95
(10 min. Hold) → 2.25% / min. At 5
0/50 → 5.0% / min. 100/0, flow rate: 1
mL / min, column oven temperature: 40 ° C., injection amount:
The stock solution was 5.0 μL.

Further, the GBL was subjected to GC analysis under the following analysis conditions 1 and 2, and as a result, the number of compounds having a concentration of 10 ppm or more was 1 and 0, respectively. GC analysis condition 1 Measurement device: GC-14 manufactured by Shimadzu Corporation, Column: HR-2
0M (0.53 mmφ, 30 m, df = 1.0 μm),
Column temperature condition: 80 ° C. to 4 ° C./minute, temperature rise to 210 ° C., and maintained at 210 ° C., carrier gas: nitrogen 40 cm /
s (50 ° C.), detector: FID, split ratio 1: 1
2. Inlet temperature 240 ° C, detector temperature 250 ° C, range 10 to the first power, sample injection amount: 0.5 μL, set waveform processing condition: SLOPE = 100 μV / sec MIN.AREA = 50 μV
-Sec. GC analysis condition 2 Measurement device: GC-17 manufactured by Shimadzu Corporation, Column: SGE
(BPX-70, 0.32 mmφ, 60 m, df = 0.
25 μm), column temperature conditions: 80 ° C. to 5 ° C./min, temperature rise to 240 ° C., carrier gas: helium 40 cm / s
(50 ° C.), detector: FID, split ratio 1:25,
Inlet temperature 240 ° C, detector temperature 260 ° C, range 10
, Power of sample injection: 1.0 μL, set waveform processing conditions:
SLOPE = 50μV / sec MIN.AREA = 0μV ・ sec
c. Example 1 2500 g of GBL and 2956 g of a 32% by weight aqueous solution of monomethylamine were charged into a 10 L SUS autoclave and reacted at 240 ° C. for 5 hours. The composition of the obtained reaction solution was N-methyl-2-pyrrolidone (NMP)
52%, 47% water, 1% monomethylamine, and other trace amounts of by-products. The obtained reaction solution is
It is continuously supplied to the middle stage of the 15-stage Oldershaw distillation column,
Under normal pressure, distillation was performed at a tower top temperature of 100 ° C. and a tower bottom temperature of 120 ° C. to obtain a monomethylamine aqueous solution from the top and an NMP aqueous solution from the bottom. This NMP aqueous solution was refluxed at a pressure of 200 mmH using a 50-stage Oldershaw distillation column.
g, water was distilled off at a tower top temperature of 65 ° C., and subsequently NMP was distilled off at a reflux ratio of 1, a pressure of 20 mmHg, and a tower top temperature of 98 ° C.

The purified NMP of 270
UV absorbance at 10 nm and 280 nm (10 millicells
absorbance) were 0.234 and 0.116, respectively. As a result of GC analysis of this NMP,
The purity was 99.97% by GC chart area ratio. Example 2 NMP was manufactured using the manufacturing apparatus shown in the flow sheet of FIG. The surface metal composition of three arbitrary inner wall compositions of the distillation column material of this apparatus and the column packing was examined by SEM-EDX analysis. Material SUS30 used for the second distillation column 3
The metal composition of No. 4 was 72% Fe, 20% Cr and 8% Ni both on the surface and inside of the first, second and third measurement points.
Met. The material of the column packing material SUS316 used for the second distillation column 3 has a surface of 69% Fe, 18% Cr,
Ni 11% and Mo 2%, with 68% Fe inside and C inside
r 18%, Ni 12% and Mo 2%.

GBL 596 Kg / Hr, monomethylamine 217 Kg / Hr, 4% by weight monomethylamine aqueous solution 576 Kg / Hr are supplied to the reactor 1, and the reaction product obtained by the reaction at 234 ° C. for a residence time of 5 hours is subjected to the first distillation. Tower 2
To remove unreacted amines as an aqueous solution from the top of the column as an aqueous solution, recover NMP containing a small amount of water from the bottom of the column, supply it to the second distillation column 3 at 820 kg / Hr, and
The water and light boiling components were distilled off from the top of the column, and NMP containing almost no water, collected from the bottom of the column, was passed to the third distillation column 4 at 760K.
g / Hr, and the product NMP is supplied to the side stream 5 of the third distillation column 4.
At 667 Kg / Hr.

As a result of measuring the UV spectrum of the obtained product NMP, the absorbance at 270 nm (10 millicell absorb
ance) was 0.191 and the absorbance at 280 nm (10 millicell absorbance) was 0.080. This NMP is G
As a result of C analysis, the NMP purity was 99.97% in terms of the area ratio of the GC chart. Example 3 Using the same apparatus as in Example 2, NMP was manufactured. In reactor 1, GBL596 kg / Hr, monomethylamine 21
7 kg / Hr, 4% by weight aqueous solution of monomethylamine 576
The reaction product obtained by supplying Kg / Hr and reacting at 234 ° C. for a residence time of 5 hours is distilled in the first distillation column 2 to flow unreacted amines as an aqueous solution from the top of the reactor 1 to form a reactor 1
The NMP containing a small amount of water is recovered from the bottom of the column, supplied to the second distillation column 3 at 820 kg / Hr, and water and light-boiling components are distilled off from the top of the second distillation column 3. NMP recovered from the bottom and containing almost no water was added to the third distillation column 4 at 760K.
g / Hr, and the product NMP is supplied to the side stream 5 of the third distillation column 4.
At 667 Kg / Hr. In this reaction, the content of monomethylamine in the mixed amine obtained by combining the newly supplied amine supplied to the reactor 1 and the recycled amine was 97.8% by weight.

As a result of measuring the UV spectrum of the obtained product NMP, the absorbance at 270 nm (10 millicell absorb) was measured.
ance) was 0.342 and the absorbance at 280 nm (10 millicell absorbance) was 0.167. This NMP is G
As a result of C analysis, the NMP purity was 99.97% in terms of the area ratio of the GC chart. Comparative Example 1 GBL 2500 g and 40 were used in the reactor used in Example 1.
2108 g of 40% by weight aqueous monomethylamine solution
1053 g of a dimethylamine aqueous solution and 350 g of a 40% by weight aqueous solution of trimethylamine were charged (the content of monomethylamine in the raw material amine mixture was 60% by weight).
The reaction was performed at 270 ° C. for 5 hours. The composition of the obtained reaction solution contained 49% of NMP, 44% of water, 7% of amines, and a small amount of by-products.

The obtained reaction solution was purified by distillation in the same manner as in Example 1 and the UV spectrum of the product NMP was measured. As a result, the absorbance at 270 nm (absorbance of 10 millicells) was obtained.
ance) was 1.613 and the absorbance at 280 nm (10 millicell absorbance) was 0.942. This NMP is G
As a result of C analysis, the NMP purity was 99.97% in terms of the area ratio of the GC chart. Comparative Example 2 GBL 2500 g, water 57
0 g, 100% monomethylamine 677 g, 40% by weight
2115 g of dimethylamine aqueous solution and 423 g of 40% by weight aqueous solution of trimethylamine were charged (the content of monomethylamine in the raw material amine mixture was 40% by weight).
The reaction was performed at 270 ° C. for 5 hours. The composition of the obtained reaction solution contained 45% of NMP, 41% of water, 13% of amines, and a small amount of by-products.

The obtained reaction solution was purified by distillation in the same manner as in Example 1, and the UV spectrum of the product NMP was measured. As a result, the absorbance at 270 nm (10 millicell absorb) was obtained.
ance) was 4.817 and the absorbance at 280 nm (10 millicell absorbance) was 2.406. This NMP is G
As a result of C analysis, the NMP purity was 99.97% in terms of the area ratio of the GC chart.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a flow sheet of an apparatus for producing an N-methyl-2-pyrrolidone composition.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 2 1st distillation tower 3 2nd distillation tower 4 3rd distillation tower 5 Product extraction port (side flow of 3rd distillation tower) 6 Amines supply line 7 γ-butyrolactone supply line 8 Water supply line

Claims (2)

[Claims] 1. 270 n measured using a 10 mm cell
An N-methyl-2-pyrrolidone composition having an absorbance at m of 1.0 or less and / or an absorbance at 280 nm of 0.5 or less. 2. A method for producing an N-methyl-2-pyrrolidone composition according to claim 1, wherein a mixture of ammonia, monomethylamine, dimethylamine and trimethylamine is reacted with a γ-butyrolactone mixture.
The content of methylamine in the amine mixture is 85% or more and the following four conditions: (a) In the distillation purification step in which the reaction mixture obtained from the reaction step is introduced, the distillation column and the distillation column are charged. Performing distillation while maintaining the content of each metal component of the product within 6% as the difference between the surface and the interior in contact with the reaction mixture;
(B) the raw γ-butyrolactone mixture does not contain impurities having a UV absorption higher than the UV spectral absorption of pure γ-butyrolactone; (c) the raw γ-butyrolactone mixture is mixed with polyethylene glycol in a fused silica tube. The number of compounds having a concentration of 10 ppm or more other than γ-butyrolactone detected by gas chromatography analysis using a chemically bonded column is 20 or less, and (d) the γ-butyrolactone raw material is fused. The number of compounds having a concentration of 10 ppm or more other than γ-butyrolactone detected by gas chromatography analysis using a column in which biscyanopropyl-methyl silicon is chemically bonded in a silica gel tube is 15 or less. Satisfies at least one condition selected from A method for producing N-methyl-2-pyrrolidone.