Method for producing N-methyl-2-pyrrolidone using polyhydroxyalkanoate and N-methyl-2-pyrrolidone prepared therefrom

Abstract

The present invention relates to a method for producing N-methyl-2-pyrrolidone using a polyhydroxyalkanoate, and N-methyl-2-pyrrolidone produced thereby, the production method comprising: (1) preparing a polyhydroxyalkanoate; (2) reacting the polyhydroxyalkanoate and an amine compound at 110 to 180 DEG C to produce an acyclic amide compound; and (3) heating the acyclic amide compound.

Description

Technical Field

[0001] The present disclosure relates to a method for preparing methylpyrrolidone (N-methyl-2-pyrrolidone, NMP), a chemical substance with high added value, using polyhydroxyalkanoate. Background Art

[0002] Biorefining is a technology for preparing biofuels (energy), electricity, heat and high value-added chemicals from biomass through biological or chemical conversion processes. This biorefining technology is similar to the oil refining technology for producing fuels and petrochemicals from crude oil as a petroleum resource. At present, oil refineries have environmental pollution problems due to the inevitable generation of greenhouse gases during processing, and there are limitations due to the consumption of petroleum resources. Therefore, research on the use of biomass rather than petroleum resources to prepare chemicals with high value-added has been carried out.

[0003] Polyhydroxyalkanoates (PHAs), as biomass, serve as storage materials within microbial cells and are attracting attention as fully degradable, biodegradable materials. In recent years, technologies have been developed to produce high-value-added chemicals or intermediates through the chemical depolymerization of PHAs. For example, methylpyrrolidone (N-methyl-2-pyrrolidone, NMP) has been produced using PHAs.

[0004] Methylpyrrolidone is chemically stable and has excellent heat resistance; therefore, it is used as a starting material for a variety of organic syntheses requiring inert media or organic solvents. Furthermore, methylpyrrolidone has high polarity and solubility; therefore, it is used as a cleaning solvent or additive in the electrical and electronic fields and the coatings industry. Furthermore, methylpyrrolidone is used as a binder component for coating cathode materials in the secondary battery industry, a key element of the energy storage technology used in energy storage systems (ESS). If polyhydroxyalkanoates (POAs) could be used as biomass to produce methylpyrrolidone, which is widely used in various fields, environmental pollution could be reduced, and POAs could become a viable alternative to depleting petroleum resources.

[0005] However, currently available methods for preparing methylpyrrolidone using polyhydroxyalkanoate are complicated, and the yield of methylpyrrolidone is unsatisfactory.

[0006] [Prior art literature]

[0007] [Patent Document]

[0008] (Patent Document 1) Korean Patent Publication No. 2011-0058002 Summary of the Invention

[0009] Technical issues

[0010] As mentioned above, conventionally, there are limitations in producing methylpyrrolidone in an environmentally friendly and high-yield manner. Specifically, 1,4-butanediol (BDO), derived from petroleum resources, is converted into a γ-butyrolactone (GBL) intermediate in the presence of a metal catalyst, which is then reacted with an alkylamine to produce methylpyrrolidone in a conventional method. However, this leads to the depletion of petroleum resources and environmental pollution, and the use of metal catalysts reduces economic viability.

[0011] Therefore, attempts have been made to produce methylpyrrolidone using polyhydroxyalkanoate as biomass in order to reduce the consumption of petroleum resources and produce methylpyrrolidone in an environmentally friendly manner. However, this has problems such as a complicated process and a reduced yield of methylpyrrolidone.

[0012] The present inventors have conducted various studies to solve these problems and have found that methylpyrrolidone can be produced in high yield by a relatively simple method by optimizing the reactants and reaction conditions used in the depolymerization reaction of polyhydroxyalkanoate.

[0013] Therefore, an object of the present disclosure is to provide a method for preparing methylpyrrolidone using polyhydroxyalkanoate in an environmentally friendly and economical manner and with high yield.

[0014] In addition, another object of the present disclosure is to provide methylpyrrolidone prepared by the above preparation method.

[0015] Solution to the problem

[0016] To achieve the above object, the present disclosure provides a method for preparing methylpyrrolidone, which comprises (1) preparing polyhydroxyalkanoate; (2) reacting the polyhydroxyalkanoate with an amine compound at 110 to 180° C. to prepare an acyclic amide compound; and (3) heating the acyclic amide compound.

[0017] According to one embodiment of the present disclosure, in step (1), the polyhydroxyalkanoate may include a repeating unit derived from 4-hydroxybutyrate (4HB).

[0018] According to another embodiment of the present disclosure, in step (2), the amine compound may include a compound selected from the group consisting of monomethylamine, a monomethylamine aqueous solution, dimethylamine, ammonia, and aqueous ammonia.

[0019] According to another embodiment of the present disclosure, in step (2), the polyhydroxyalkanoate and the amine compound may be reacted at an equivalent ratio of 1:1.01 to 2.5.

[0020] According to another embodiment of the present disclosure, in step (2), the reaction time of the polyhydroxyalkanoate and the amine compound may be 10 hours or less.

[0021] According to another embodiment of the present disclosure, in step (2), the acyclic amide compound may include a compound selected from the group consisting of 4-hydroxy-N-methylbutanamide, 4-hydroxybutanamide, and 4-hydroxy-N-(2-hydroxyethyl)butanamide.

[0022] According to another embodiment of the present disclosure, in step (3), the heating temperature of the acyclic amide compound may be 200° C. or higher.

[0023] According to another embodiment of the present disclosure, in step (3), the initial pressure of heating the acyclic amide compound may be 1 to 80 bar.

[0024] According to another embodiment of the present disclosure, in step (3), the difference (P2-P1) between the initial pressure (P1) of heating the acyclic amide compound and the equilibrium pressure (P2) after heating for 1 hour may be 15 bar or greater.

[0025] According to another embodiment of the present disclosure, in step (3), the heating time of the acyclic amide compound may be 1 to 8 hours.

[0026] According to another embodiment of the present disclosure, in step (2), the conversion rate of the polyhydroxyalkanoate may be 80% or higher, and the selectivity of the acyclic amide compound may be 90% or higher.

[0027] According to another embodiment of the present disclosure, in step (3), the conversion rate of the acyclic amide compound may be 90% or higher.

[0028] According to another embodiment of the present disclosure, when prepared by the above preparation method, the yield of methylpyrrolidone is 90% or more.

[0029] Meanwhile, in order to achieve the above objectives, the present disclosure provides methyl pyrrolidone prepared by the above preparation method.

[0030] Beneficial effects of the present invention

[0031] Since the present disclosure uses polyhydroxyalkanoate (which is biomass) rather than petroleum resources as a starting material to produce methylpyrrolidone, methylpyrrolidone can be produced in an environmentally friendly manner while reducing the consumption of petroleum resources. In addition, the present disclosure can produce methylpyrrolidone economically and in high yield by optimizing the depolymerization reaction of polyhydroxyalkanoate to produce methylpyrrolidone. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart illustrating a method for preparing methylpyrrolidone according to an embodiment of the present disclosure.

[0033] Best Mode for Carrying Out the Invention

[0034] Hereinafter, the present disclosure will be described in detail. The present disclosure is not limited to the disclosure given below, but can be modified into various forms as long as the gist of the present disclosure is not changed.

[0035] In this specification, the term "comprising" is intended to specify specific features, regions, steps, processes, elements and / or components. It does not exclude the existence or addition of any other features, regions, steps, processes, elements and / or components, unless specifically stated to the contrary.

[0036] All numbers and expressions relating to quantities of components, reaction conditions, and so forth used herein are to be understood as modified by the term "about," unless otherwise indicated.

[0037] The present disclosure provides a method for producing methylpyrrolidone using polyhydroxyalkanoate as biomass, and methylpyrrolidone produced by the method. The present disclosure is characterized in that by optimizing the reactants and reaction conditions used in the depolymerization process of polyhydroxyalkanoate, methylpyrrolidone can be produced in high yield in an environmentally friendly and economical manner. This will be described in detail below.

[0038] Method for preparing methylpyrrolidone

[0039] The method for preparing methylpyrrolidone according to the present disclosure includes (1) preparing polyhydroxyalkanoate; (2) reacting the polyhydroxyalkanoate with an amine compound at 110 to 180° C. to prepare an acyclic amide compound; and (3) heating the acyclic amide compound.

[0040] In the following, reference will be made to Figure 1 To explain each step.

[0041] Step (1): Preparation of polyhydroxyalkanoate

[0042] According to the present disclosure, step (1) is to prepare polyhydroxyalkanoate, which is biomass.

[0043] Polyhydroxyalkanoate (PHA) is a naturally occurring thermoplastic polyester polymer that accumulates within microbial cells. It possesses physical properties similar to those of synthetic biodegradable polymers derived from petroleum, such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), and polybutylene succinate adipate (PBSA), while exhibiting superior biodegradability and biocompatibility.

[0044] Polyhydroxyalkanoate can be obtained by mechanical or physical cell disruption, or by non-mechanical or chemical cell disruption. Specifically, polyhydroxyalkanoate can be obtained by microbial cell disruption using at least one selected from the group consisting of ultrasonic disruption, high-pressure disruption, and grinding disruption.

[0045] Ultrasonic disruption can be carried out at an energy level of 20 Hz or higher for 10 to 60 minutes. Specifically, ultrasonic disruption can be carried out at an energy level of 60 Hz or lower, 50 Hz or lower, or 40 Hz or lower for 10 to 60 minutes, 15 to 55 minutes, or 20 to 50 minutes.

[0046] High-pressure crushing can be carried out at a pressure of 10 bar or more for 1 to 60 minutes. Specifically, high-pressure crushing can be carried out at a pressure of 10 bar or more, 20 bar or more, or 50 bar or more for 1 to 60 minutes, 2 to 60 minutes, or 3 to 60 minutes.

[0047] The grinding and crushing can be performed using a colloid mill, a bead mill, or a ball mill for 1 to 60 minutes, 2 to 60 minutes, or 3 to 60 minutes.

[0048] More specifically, polyhydroxyalkanoates can be obtained by enzyme-catalyzed polymerization of one or more monomers (monomer repeating units) within microbial cells, followed by cell disruption.

[0049] The purity of the polyhydroxyalkanoate obtained in this manner can be 90% or higher, specifically, 92% or higher, 94% or higher, 96% or higher, 98% or higher, 99% or higher, or 99.9% or higher (e.g., 90 to 100%, 95 to 100%, or 98 to 99.5%), but is not limited thereto.

[0050] The weight average molecular weight of polyhydroxyalkanoate (M w ) may be 100,000 to 1,200,000 g / mol, 50,000 to 1,000,000 g / mol, 100,000 to 900,000 g / mol, 150,000 to 800,000 g / mol, 200,000 to 700,000 g / mol, or 250,000 to 600,000 g / mol, but is not limited thereto.

[0051] The glass transition temperature (T g ) may be -45 to 80°C, -35 to 70°C, -30 to 60°C, -25 to 50°C, -20 to 30°C, -15 to 15°C, or -15 to 0°C, but is not limited thereto.

[0052] The crystallization temperature of polyhydroxyalkanoate (T c ) may or may not be measurable. Specifically, the crystallization temperature (T c ) may not be measurable, or may be 70 to 120° C., 75 to 120° C., 75 to 115° C., 75 to 110° C., or 80 to 110° C., but is not limited thereto.

[0053] The melting temperature of polyhydroxyalkanoate (T m ) may or may not be measurable. Specifically, the melting temperature (T m ) may not be measurable, or may be 100 to 170° C., 110 to 150° C., 115 to 145° C., or 120 to 140° C., but is not limited thereto.

[0054] The decomposition temperature of polyhydroxyalkanoate (T d ) may be 140 to 310°C, 160 to 290°C, 190 to 260°C, or 220 to 230°C, but is not limited thereto. For example, the decomposition temperature (T d ) can be from 140 to 160°C, from 190 to 220°C, from 230 to 260°C, or from 290 to 310°C.

[0055] The polydispersity index (PDI) of the polyhydroxyalkanoate may be 1.0 or greater, 1.2 or greater, 1.5 or greater, 1.8 or greater, 1.9 or greater, or 2.0 or greater, and 5.0 or less, 4.0 or less, 3.0 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, or 2.5 or less, but is not limited thereto.

[0056] Polyhydroxyalkanoate can include repeating units (4HB repeating units) derived from 4-hydroxybutyrate (4HB). Specifically, polyhydroxyalkanoate can be a polymer form consisting only of 4HB repeating units, or a copolymer form comprising 4HB repeating units and repeating units different from 4HB repeating units. More specifically, polyhydroxyalkanoate can be selected from the group consisting of poly-4-hydroxybutyrate (P4HB) and poly (3-hydroxybutyrate-to-4-hydroxybutyrate) (P3HB-co-4HB), but is not limited thereto. When polyhydroxyalkanoate is one of the above-mentioned substances, it has excellent reactivity with amine compounds, so that it can be easily converted into acyclic amide compounds. As a result, methyl pyrrolidone can be prepared in an environmentally friendly manner and with high yield.

[0057] Meanwhile, the crystallinity of polyhydroxyalkanoates (PHAs) can be adjusted according to the content of 4HB repeating units. Polyhydroxyalkanoates (PHAs) can be divided into semicrystalline PHAs (scPHAs) and amorphous PHAs (aPHAs).

[0058] Specifically, the 4HB repeating unit content of the semi-crystalline PHA (scPHA) may be 0.1 to 30 wt%, 1 to 28 wt%, 3 to 26 wt%, 5 to 25 wt%, 8 to 23 wt%, 10 to 20 wt%, or 10 to 15 wt%, based on the total weight of the polyhydroxyalkanoate (PHA). In addition, the 4HB repeating unit content of the amorphous PHA (aPHA) may be 15 to 60 wt%, 20 to 58 wt%, 25 to 55 wt%, 30 to 53 wt%, 35 to 50 wt%, 40 to 49 wt%, or 45 to 48 wt%, based on the total weight of the polyhydroxyalkanoate (PHA).

[0059] The polyhydroxyalkanoate (PHA) may be composed of a single semicrystalline PHA (scPHA), a single amorphous PHA (aPHA), or a mixture thereof. Specifically, it may be an amorphous PHA (aPHA). For example, when the polyhydroxyalkanoate (PHA) is poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB-co-4HB), it may be an amorphous P3HB-co-4HB having a 4HB repeating unit content of 15 to 60 wt%.

[0060] Step (2): Preparation of acyclic amide compounds

[0061] According to the present disclosure, step (2) is to react polyhydroxyalkanoate with an amine compound at a specific temperature to prepare an acyclic amide compound in high yield.

[0062] The reaction temperature of the polyhydroxyalkanoate and the amine compound may be 110 to 180° C. Specifically, the reaction temperature may be 110 to 175° C., 113 to 170° C., 113 to 165° C., 115 to 160° C., 115 to 155° C., 118 to 150° C., 118 to 145° C., or 120 to 140° C., but is not limited thereto.

[0063] The reaction time of the polyhydroxyalkanoate and the amine compound may be 10 hours or less. Specifically, the reaction time may be 9 hours or less, 8 hours or less, 7 hours or less, or 6 hours or less (e.g., 1 to 10 hours, 2 to 10 hours, 3 to 10 hours, or 6 to 10 hours), but is not limited thereto.

[0064] In addition, the reaction ratio between the polyhydroxyalkanoate and the amine compound may be an equivalent ratio of 1:1.01 to 2.5. Specifically, the reaction ratio may be an equivalent ratio of 1:1.05 to 2.4, an equivalent ratio of 1:1.08 to 2.3, an equivalent ratio of 1:1.1 to 2.25, or an equivalent ratio of 1:1.1 to 2.2, but is not limited thereto.

[0065] When the reaction temperature, reaction time, and reaction ratio each satisfy the above ranges, polyhydroxyalkanoate is easily converted into an acyclic amide compound, which allows the production of methylpyrrolidone in high yield.

[0066] The amine compound is not particularly limited as long as it is a compound capable of depolymerizing polyhydroxyalkanoate. Specifically, the amine compound may include a compound selected from the group consisting of monomethylamine, a monomethylamine aqueous solution, dimethylamine, ammonia, and aqueous ammonia. When the amine compound includes the above compounds, the selectivity and yield of the acyclic amide compound to methylpyrrolidone can be improved.

[0067] The amine compound may be in the form of a gas or an aqueous solution (concentration: 25 to 40% by weight).

[0068] In addition, the amine compound may have a vapor density of 0.52 to 1.65, specifically, 0.58 to 1.61, a boiling point of -40 to -2°C, specifically, -33 to -6°C, and a pH of 10.8 to 11.8, specifically, 11.2 to 11.5, but is not limited thereto.

[0069] Meanwhile, the acyclic amide compound obtained by the reaction of polyhydroxyalkanoate with an amine compound may include a compound selected from the group consisting of 4-hydroxy-N-methylbutanamide, 4-hydroxybutanamide, and 4-hydroxy-N-(2-hydroxyethyl)butanamide, but is not limited thereto.

[0070] The acyclic amide compound may have a boiling point of 100 to 110° C. or 150 to 160° C. at 0.2 Torr and a boiling point of 230 to 250° C. at normal pressure, but is not limited thereto.

[0071] When step (2) is performed, the present invention has a high polyhydroxyalkanoate conversion rate (the ratio of polyhydroxyalkanoate conversion to acyclic amide compounds) and a high acyclic amide compound selectivity, which allows the production of methylpyrrolidone in high yield.

[0072] Specifically, according to the present disclosure, the conversion rate of polyhydroxyalkanoate can be 80% or more, 82% or more, 84% or more, 86% or more, 88% or more, or 90% or more (e.g., 80 to 100%, 83 to 100%, 85 to 100%, or 90 to 99.9%), but is not limited thereto.

[0073] Furthermore, according to the present disclosure, the selectivity of acyclic amide compounds can be 90% or more, 92% or more, 94% or more, 96% or more, 98% or more, or 99% or more (e.g., 90 to 100%, 92 to 100%, 94 to 99.9%, or 97 to 99.9%), but is not limited thereto.

[0074] According to the present disclosure, the yield of the acyclic amide compound can be 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, or 90% or more (e.g., 50 to 100%, 70 to 100%, 85 to 99.9%, or 90 to 99.9%), but is not limited thereto.

[0075] Step (3): Heating the acyclic amide compound

[0076] According to the present disclosure, step (3) is to heat the acyclic amide compound under relatively high temperature and pressure conditions. Specifically, heating the acyclic amide compound under high temperature and pressure conditions causes a condensation cyclization reaction to generate methylpyrrolidone.

[0077] The heating temperature of the acyclic amide compound may be 200° C. or higher, specifically, 210° C. or higher, 220° C. or higher, 230° C. or higher, 240° C. or higher, or 250° C. or higher (e.g., 200 to 300° C., 210 to 290° C., 220 to 280° C., 230 to 275° C., 235 to 270° C., 240 to 260° C., or 245 to 255° C.), but is not limited thereto.

[0078] In addition, the initial pressure (set pressure) of heating the acyclic amide compound may be 1 to 80 bar, specifically, 1 to 75 bar, 1 to 70 bar, 1 to 65 bar, 3 to 60 bar, 5 to 60 bar, or 10 to 60 bar, but is not limited thereto.

[0079] In addition, the difference (P2-P1) between the initial pressure (P1) when the acyclic amide compound is heated and the equilibrium pressure (P2) after heating for 1 hour may be 15 bar or more. Specifically, the pressure difference (P2-P1) may be 16 bar or more, 17 bar or more, 18 bar or more, 20 bar or more, 23 bar or more, or 25 bar or more, and 100 bar or less, 90 bar or less, 80 bar or less, or 70 bar or less (e.g., 15 to 100 bar, 17 to 95 bar, 19 to 90 bar, 20 to 85 bar, 25 to 80 bar, or 27 to 75 bar), but is not limited thereto.

[0080] In addition, the heating time of the acyclic amide compound may be 1 to 8 hours, specifically, 1 to 7 hours, 2 to 6 hours, 2 to 5 hours, or 3 to 4 hours, but is not limited thereto.

[0081] When the heating temperature, initial pressure, pressure difference (P2-P1) and heating time are each within the above ranges, the reaction stability of the acyclic amide compound is ensured, and the acyclic amide compound is easily converted into methylpyrrolidone. This allows methylpyrrolidone to be produced in high yield.

[0082] If methylpyrrolidone is produced as in step (3), specifically, if step (3) is a step of heating an acyclic amide compound to produce methylpyrrolidone, the present disclosure has a high acyclic amide compound conversion rate (ratio of conversion of the acyclic amide compound to methylpyrrolidone) and a high methylpyrrolidone selectivity. This allows methylpyrrolidone to be produced in high yield.

[0083] Specifically, according to the present disclosure, the conversion rate of the acyclic amide compound can be 90% or more, 92% or more, 95% or more, 97% or more, 99% or more, or 99.9% or more (e.g., 90 to 100%, 92 to 100%, 95 to 100%, 98 to 100%, or 99.9 to 100%), but is not limited thereto.

[0084] Furthermore, according to the present disclosure, the selectivity of methylpyrrolidone can be 85% or more, 88% or more, 90% or more, 92% or more, 95% or more, 97% or more, 99% or more, or 99.9% or more (e.g., 85 to 100%, 88 to 100%, 90 to 100%, 95 to 99.9%, or 99 to 99.9%), but is not limited thereto.

[0085] In addition, according to the present disclosure, the yield of methylpyrrolidone can be 90% or more, 91% or more, 92% or more, 94% or more, 96% or more, 98% or more, 99% or more, or 99.9% or more (e.g., 90 to 100%, 91 to 100%, 92 to 100%, 95 to 99.9%, or 99 to 99.9%), but is not limited thereto.

[0086] Methylpyrrolidone

[0087] The methylpyrrolidone according to the present disclosure is prepared by the above-mentioned preparation method. That is, because the present disclosure uses polyhydroxyalkanoate to prepare methylpyrrolidone, high-purity methylpyrrolidone can be provided in a high yield in an environmentally friendly and economical manner.

[0088] Specifically, according to the present disclosure, methylpyrrolidone can have a high purity of at least 87% or more, 90% or more, 92% or more, 95% or more, or 98% or more (e.g., 87 to 99.9%, 87 to 99%, or 87 to 98%).

[0089] Furthermore, the methylpyrrolidone may contain less than 0.1% by weight of 2-pyrrolidone as a by-product.

[0090] The methylpyrrolidone according to the present disclosure can be advantageously used in various fields, such as electrical and electronic fields, energy fields (e.g., secondary batteries), chemical fields (e.g., organic synthesis and organic solvents), or coating fields (e.g., detergents and additives).

[0091] Modes for Carrying Out the Invention

[0092] Hereinafter, the present disclosure will be described in detail with reference to Examples, but the scope of the present disclosure is not limited to these Examples.

[0093] [Reagents and analytical equipment]

[0094] Chloroform (>99.5%; Daejeong Chemical and Metals), methanol (EP grade; Daejeong Chemical and Metals), ethanol (GR grade; Duksan Pure Chemicals), acetonitrile (HPLC grade; BURDICK & JACKSON), and monomethylamine (40 wt % aqueous solution; Samchun Pure Chemical) were the reagents used in the Examples, Comparative Examples, and Test Examples.

[0095] In addition, high performance liquid chromatography (HPLC) and gas chromatography were used as analytical equipment.

[0096] Specifically, Agilent Technologies' 1260infinity device was used as the HPLC instrument, and Osaka Soda's Capcell Pak C18 MG (4.6 mm × 250 mm × 5 μm, P / N 92635) was used as the chromatographic column. The autosampler temperature was set to 15° C., the column temperature was set to 35° C., and triple-distilled water containing 0.2% phosphoric acid and acetonitrile (ACN) were used as the mobile phase solvents. Analysis was performed using gradient elution at a mobile phase flow rate of 1 ml / min.

[0097] A GC (Agilent Technologies, 8890) equipped with a DB-WAX (60 m × 250 μm × 0.25 μm) column was used as the GC instrument. The inlet temperature was set to 250°C and the flow rate was 1 ml / min. The flame ionization detector (FID) temperature was set to 300°C for analysis.

[0098] [Example 1]

[0099] Preparation (Purification) of Poly (4-Hydroxybutyrate) (P4HB)

[0100] 300ml of bacterial liquid containing poly 4-hydroxybutyrate (P4HB) is added to a centrifuge and centrifuged at 3,000rpm for 5 minutes to remove the supernatant. Next, 300ml of primary distilled water is added, the cells are disentangled by vortexing, and centrifuged again. Subsequently, the supernatant is removed again, 150g of chloroform is added, and a mechanical stirrer is used to stir for 2 hours at 45°C. Next, the supernatant is removed, and only the chloroform layer is slowly added to an excess of ethanol (EtOH) to precipitate P4HB. Thereafter, ethanol (EtOH) and chloroform are removed by drying to obtain a P4HB precipitate. The P4HB precipitate obtained is a white solid, and its purity is confirmed to be 99%.

[0101] Preparation of 4-hydroxy-N-methylbutyramide (4HBA)

[0102]

[0103] 0.2 g (1 equivalent) of P4HB obtained through the above purification and 0.2 g (1.1 equivalents) of monomethylamine (MMA, a 40 wt% aqueous solution) were added to a 48 ml screw-capped tube and stirred at 300 rpm to prepare a mixture. The mixture was then reacted at 120° C. for 6 hours to prepare 4HBA.

[0104] [Examples 2 to 10 and Comparative Examples 1 to 9]

[0105] 4HBA was prepared according to the same procedure as in Example 1, except that the reaction temperature and time of the mixture of P4HB and MMA and the equivalent ratio of P4HB and MMA were changed, as shown in Table 1 below.

[0106] [Test Example 1]

[0107] In each of Examples 1 to 10 and Comparative Examples 1 to 9, the P4HB remaining after preparing 4HBA was separated using filter paper and then weighed to calculate the conversion rate of P4HB. The results are shown in Table 1 below. In addition, the selectivity and yield of 4HBA in the reaction solution were analyzed using a high performance liquid chromatograph (HPLC) and calculated using the following equation. The results are shown in Table 1 below.

[0108] [Equation 1]

[0109] 4HBA selectivity (%) = (the number of moles of 4HBA produced / the number of moles of 4HB in the converted P4HB) × 100

[0110] [Equation 2]

[0111] 4HBA yield (%) = P4HB conversion × 4HBA selectivity

[0112] [Table 1]

[0113]

[0114] Referring to Table 1 above, in the present disclosure, when the mixture of P4HB and MMA was reacted at a temperature of 110° C. or higher (Examples 1 to 10), the P4HB conversion rate and 4HBA selectivity increased, thereby obtaining 4HBA in high yield. In contrast, when the mixture of P4HB and MMA was reacted at a low temperature of 90° C. or lower, the P4HB conversion rate and 4HBA selectivity decreased, thereby reducing the yield of 4HBA.

[0115] [Example 11]

[0116] Preparation of methyl-2-pyrrolidone (NMP)

[0117] The 4HBA obtained in Example 4 was dried at 50 ° C in a vacuum oven (BF-60VO, Biofree) for 16 hours, and 20 g of it was added to a high-temperature and high-pressure reactor (R-101 high-pressure bomb system, Chemesis). After the initial pressure (P1) was adjusted to normal pressure (1 bar), the reaction was continued at 250 ° C for 3 hours. Here, the equilibrium pressure (P2) was measured after 1 hour of reaction. After the reaction was completed, the product was diluted with methanol and recovered to obtain N-methyl-2-pyrrolidone (NMP).

[0118] [Examples 12 to 15]

[0119] NMP was prepared according to the same procedure as in Example 11, except that the initial pressure was adjusted by injecting nitrogen, as shown in Table 2 below.

[0120] [Comparative Example 10]

[0121] NMP was prepared according to the same procedure as in Example 11, except that 4HBA obtained in Comparative Example 6 was used.

[0122] [Test Example 2]

[0123] In each of Examples 11 to 15 and Comparative Example 10, the 4HBA remaining after the NMP production was separated using filter paper and then weighed to calculate the conversion of 4HBA. The results are shown in Table 2 below. In addition, the selectivity and yield of NMP were analyzed using a gas chromatograph (GC) and calculated using the following equation. The results are shown in Table 2 below.

[0124] [Equation 3]

[0125] NMP selectivity (%) = (moles of NMP produced / moles of 4HBA converted) × 100 [Equation 4]

[0126] NMP yield (%) = 4HBA conversion × NMP selectivity

[0127] [Table 2]

[0128]

[0129] Referring to Table 2 above, in the present disclosure, when 4HBA is reacted under relatively high temperature and pressure conditions, the 4HBA conversion rate and NMP selectivity are high, and thus NMP is obtained in high yield.

Claims

1. A method for preparing methylpyrrolidone, the method comprising: (1) Preparation of polyhydroxyalkanoate; (2) reacting the polyhydroxyalkanoate with an amine compound at 110 to 180° C. to prepare an acyclic amide compound; and (3) Heating the acyclic amide compound.

2. The method for preparing methylpyrrolidone according to claim 1, wherein In step (1), the polyhydroxyalkanoate comprises repeating units derived from 4-hydroxybutyrate (4HB).

3. The method for preparing methyl pyrrolidone according to claim 1, wherein In step (2), the amine compound includes a compound selected from the group consisting of monomethylamine, a monomethylamine aqueous solution, dimethylamine, ammonia, and aqueous ammonia.

4. The method for preparing methylpyrrolidone according to claim 1, wherein In step (2), the polyhydroxyalkanoate and the amine compound are reacted at an equivalent ratio of 1:1.01 to 2.

5.

5. The method for preparing methylpyrrolidone according to claim 1, wherein In step (2), the reaction time of the polyhydroxyalkanoate and the amine compound is 10 hours or less.

6. The method for preparing methylpyrrolidone according to claim 1, wherein In step (2), the acyclic amide compound includes a compound selected from the group consisting of 4-hydroxy-N-methylbutanamide, 4-hydroxybutanamide, and 4-hydroxy-N-(2-hydroxyethyl)butanamide.

7. The method for preparing methylpyrrolidone according to claim 1, wherein In step (3), the heating temperature of the acyclic amide compound is 200° C. or higher.

8. The method for preparing methylpyrrolidone according to claim 1, wherein In step (3), the initial pressure of heating the acyclic amide compound is 1 to 80 bar.

9. The method for preparing methylpyrrolidone according to claim 1, wherein In step (3), the difference (P2-P1) between the initial pressure (P1) of heating the acyclic amide compound and the equilibrium pressure (P2) after heating for 1 hour is 15 bar or greater.

10. The method for preparing methylpyrrolidone according to claim 1, wherein In step (3), the heating time of the acyclic amide compound is 1 to 8 hours.

11. The method for preparing methylpyrrolidone according to claim 1, wherein In step (2), the conversion rate of the polyhydroxyalkanoate is 80% or more, and the selectivity of the acyclic amide compound is 90% or more.

12. The method for preparing methylpyrrolidone according to claim 1, wherein In step (3), the conversion rate of the acyclic amide compound is 90% or more.

13. The method for preparing methylpyrrolidone according to claim 1, wherein the yield of methylpyrrolidone is 90% or more.

14. Methylpyrrolidone produced by the production method according to any one of claims 1 to 13.

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