JP2002017384A - Method for producing trimethylene carbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an environmentally acceptable method of low energy consumption for producing trimethylene carbonate by selectively converting a trimethylene carbonate polymer to a repolymerizable monomer using an enzyme reaction. SOLUTION: This method for producing trimethylene carbonate is characterized by comprising depolymerizing a trimethylene carbonate polymer in the presence of a hydrolase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing a 6-membered trimethylene carbonate monomer (1,3-dioxan) from a trimethylene carbonate polymer utilizing a reversible reaction between the synthesis and decomposition of a polymer compound by an enzyme. -2-o
ne).

[0002]

2. Description of the Related Art In a crisis situation in which the global environment is increasingly deteriorating due to global warming in recent years, from the viewpoint of effective use of limited carbon resources (C resources) and saving of finite energy resources, sustainable (sustainable) ) The construction of the material system is urgent. Regarding polymer products, after use, they are reused as they are (including the use of PET bottles as a fiber material), recycled, or discarded. As the recycling method, the Material Recycling Law, the Chemical Recycling Law, the Thermal Recycling Law, etc. are used. The Thermal Recycling Law involves problems such as the generation of a large amount of carbon dioxide gas, and ultimately, any method will discharge waste plastic, which is currently treated by incineration and landfill. is there. From the viewpoint of effective utilization of carbon resources, it is ideal to return to raw materials by the chemical recycling method. In the chemical recycling method, the recovery of monomers by a depolymerization reaction and the recovery of raw material monomers by a chemical decomposition reaction are known. However, all of them are energy-consuming, have a large burden on the environment, and are generally not profitable.

[0003] Although deviating from the viewpoint of reuse, so-called biodegradable polymers that are biodegraded by underground bacteria and the like have attracted attention as polymers having a small environmental load, and various biodegradable polymers have been proposed. I have. For example, biodegradable polyesters are known as biodegradable polymers. However, conventional biodegradable polyesters are susceptible to hydrolysis and thus have poor water resistance, and their use range and life are limited. In order to improve this hydrolyzability, poly (trimethylene carbonate) in which a carbonate bond is introduced into a polymer skeleton has become known. Poly (trimethylene carbonate) is a polymer material that has excellent biodegradability, biocompatibility, biosafety, and bioabsorbability. In the pharmaceutical field, it is used as a pharmaceutical base, sustained release drug base, and cosmetics. It can be used as a general-purpose polymer as an amorphous rubber-like polymer, including the use as a raw material. However, although biodegradable polymers such as poly (trimethylene carbonate) have a small impact on the environment, their raw materials are not recovered. Therefore, from the viewpoint of complete recycling using carbon resources, the ideal polymer is used. It is hard to say the decomposition method. Therefore, unlike biodegradable polymers, it can be decomposed into low molecular compounds without the need for high energy such as using petroleum energy, and low molecular compounds can be used effectively. Similarly, if energy can be obtained without consuming high energy, a low-energy-consuming and completely-circulating polymer production / decomposition method can be constructed.

Conventionally, phosgene is generally used for the production of aliphatic polycarbonates such as poly (trimethylene carbonate), and toxic or coexisting solvents such as halogenated hydrocarbons may cause environmental problems. Due to the adverse effects, mass production has significant problems and alternatives are being sought.

As a method for producing poly (alkylene carbonate), there is a method for producing a poly (alkylene carbonate) by chemical transesterification and polycondensation of a carbonate and a diol. In this method, polymerization is carried out at 130 to 170 ° C. under normal pressure in the presence of a metal catalyst, and then polymerization is carried out under reduced pressure (Poly).
mer J., 14,839,1982). However, this method also has a drawback that the reaction is carried out at a relatively high temperature, and the formation of an ether bond by decarboxylation occurs as a side reaction, resulting in a decrease in the function and biodegradability of the obtained polymer. In addition, a method of reacting carbon monoxide with a diol in the presence of a noble metal catalyst or the like (Japanese Patent Laid-Open No. 5-39247) or polycondensation of a carbonate and a dihalide in N-methylpyrrolidone in the presence of a catalyst in a carbon dioxide gas atmosphere Method (industrial materials, 44, 9, 19)
96) have been proposed. However, these methods also have drawbacks such as the use of a solvent that adversely affects the environment and the inability to obtain high molecular weight poly (alkylene carbonate).

On the other hand, there is a method in which cyclic carbonate is subjected to ring-opening polymerization using a metal catalyst. However, the production of a cyclic carbonate monomer requires a large number of steps and requires a metal catalyst. .

In order to solve the problems of the method for producing poly (alkylene carbonate) by the organic synthesis method, the present inventors first reacted a dialkyl carbonate with an alkanediol in the presence of an enzyme. A method for producing poly (trimethylene carbonate) was developed (Kawaken Fine Chemical Co., Ltd., Shuichi Matsumura, JP-A-2000-80160, "Method for producing poly (trimethylene carbonate) by enzymatic method", Heisei March 21, 2012).

Further, the present inventors have proposed that cyclic carbonates, such as trimethylene carbonate, can be used as one of the lipases.
A method of ring-opening polymerization using PPL (porcine pancreatic lipase) as a seed was also provided (Matsumura, S .; Ts.
ukada, K .; Toshima, K. Macromolecules 1997, 30, 312
2). However, in this case trimethylene carbonate is
It is manufactured from 1,3-propanediol and ethyl chloroformate. It has been reported that cyclic carbonates such as trimethylene carbonate easily undergo enzymatic polymerization, and not only homopolymers, but also copolymers obtained by copolymerization with lactide or ε-caprolactone can be obtained. The application is expected to develop in the future. ("Matsumura, S .; Tsukada, K .; Tosh
ima, K. Macromolecules 1997, 30, 3122 "," Kobayash
i, S .; Kikuchi, H .; Uyama, H. Macromol.Rapid. Commun.
1997, 18, 575 '', `` Bisht, KS; Svirkin, YY; Hende
rson, LA; Gross, RA; Kaplan, DL; Swift, G. Macro
molecules 1997,30,7735 '', `` Matsumura, S .; Tsukad
a, K .; Toshima, K. Int. J. Biolog. Macromol. 1999,2
5,161 "," Deng, F .; Gross, RA Int. J. Biolog. Ma
cromol. 1999, 25, 153. ") However, as described above, trimethylene carbonate is only produced by an organic synthesis method.

Accordingly, the aliphatic polycarbonate can be decomposed without applying high energy, and the resulting decomposed product is converted into polytrimethylene carbonate without applying high energy like trimethylene carbonate. If the decomposition product can be used, a method for producing and decomposing an aliphatic polycarbonate which is low in energy consumption and completely circulating can be achieved. However, such a method has not been found so far.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for selectively converting a trimethylene carbonate polymer to a repolymerizable monomer by using an enzyme. By using a reaction, the method is provided as a low energy consumption and environmentally acceptable method.

[0011]

The above object can be attained by providing the following process for producing trimethylene carbonate. (1) A method for producing trimethylene carbonate, comprising depolymerizing a trimethylene carbonate polymer in the presence of a hydrolase. (2) The method for producing trimethylene carbonate according to (1), wherein the hydrolase is lipase. (3) The method for producing trimethylene carbonate according to (1) or (2), wherein the lipase is derived from Candida antarctica.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing a 6-membered trimethylene carbonate monomer by depolymerizing a trimethylene carbonate polymer in the presence of a hydrolase, and hydrolyzing the trimethylene carbonate monomer. The present invention relates to a method for producing a trimethylene carbonate polymer by polymerizing in the presence of a lipase derived from Candida antarctica, one of the enzymes. The 6-membered ring trimethylene carbonate monomer (1,3-dioxan-2-one) formed by the depolymerization of the present invention is represented by the following structural formula.

[0013]

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The trimethylene carbonate polymer of the present invention is a polymer having a repeating unit represented by the following structural formula in the molecule. In order to efficiently recover trimethylene carbonate using the depolymerization method of the present invention,
The polymer preferably contains the following unit structure in an amount of 50 mol% or more.

[0015]

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The terminal group in the above formula can be substituted by any one determined by a polymer synthesis method. In addition to the above units, a repeating unit represented by the following structural formula (A), structural formula (B) or structural formula (C) can be contained. Preferably, the content of said units is lower than 50 mol%.

[0017]

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In the formula, R ₁ represents a linear or branched alkylene group having 1 to 17 carbon atoms, R ₂ represents a linear or branched alkylene group having 2 to 11 carbon atoms (excluding 3), and R ₃ represents a carbon atom. R 1 represents a linear or branched alkylene group having 1 to 10 carbon atoms, and R ₄ represents a linear or branched alkylene group having 2 to 10 carbon atoms.

[Depolymerization of trimethylene carbonate polymer] In the depolymerization of the trimethylene carbonate polymer of the present invention, the trimethylene carbonate polymer is dissolved in an appropriate solvent, and a hydrolytic enzyme is added thereto to prepare a depolymerization solution. It is prepared by carrying out a depolymerization reaction for a suitable period of time while preparing and maintaining the solution at a suitable temperature, preferably with stirring. As the enzyme used in the depolymerization of the present invention, a hydrolase that hydrolyzes a carbonate bond is used without any particular limitation. As a hydrolase, lipase is preferred because of its availability and thermostability of the enzyme.
A lipase derived from antarctica (hereinafter sometimes referred to as “CA lipase”) is preferred. Further, the enzyme may or may not be immobilized. Cand
Examples of enzymes derived from ida antarctica include Novo Nordisk Bioindustry's Nov, an immobilized enzyme.
ozym 435 (trade name). In the present invention, the amount of the enzyme (including the immobilized enzyme) to be added is 50 to 3000% by weight of the enzyme per polymer, preferably,
100 to 1500% by weight of the enzyme. If the amount is less than 5% by weight, the reaction is biased toward polymerization, and the production of monomers is significantly reduced.
If it exceeds 3000% by weight, the trimethylene carbonate monomer undergoes further enzymatic decomposition, and is further decomposed into carbon dioxide and diol, and the monomer yield is remarkably reduced.

As the solvent, acetonitrile, 1,4
Dissolving a trimethylene carbonate polymer such as dioxane, tetrahydrofuran, isopropyl ether,
Any solvent that does not deactivate the enzyme can be used without limitation. Water and alcohol are not preferred because they cause enzymatic degradation of the resulting trimethylene carbonate. The concentration of the trimethylene carbonate polymer in the solution for depolymerization is suitably 0.05 to 10% by weight. Further, although water is not suitable as a solvent, a small amount of water is preferably added to the depolymerization system since the activity of the hydrolase cannot be maintained unless water is present in the depolymerization system. If the enzyme itself retains water, there is no need to add water. Water for maintaining the activity of the enzyme is 0.1 to 5 with respect to the trimethylene carbonate polymer in the reaction system.
% By weight. The temperature for the depolymerization is from 40 to 90C, preferably from 60 to 75C. When the temperature is lower than 40 ° C., the depolymerization rate is low, and when the temperature is higher than 90 ° C., the enzyme is easily deactivated, so the above range is appropriate. Further, the reaction time of the depolymerization is desirably at least 10 hours.
The upper limit of the reaction time is not particularly limited, but even if the reaction is carried out for 96 hours or more, the depolymerization does not proceed any more and it is economically disadvantageous, so the above range is appropriate. 10 to 48 hours are typical reaction times. In the depolymerization reaction of the present invention, for example, a poly (trimethylene carbonate) is treated with an enzyme to obtain a trimethylene carbonate monomer (1,3-
dioxan-2-one) can be obtained in a yield of 80% or more.

The method for depolymerizing the trimethylene carbonate polymer with the hydrolase of the present invention may be a simple one-pot operation, and the reaction conditions are mild and consume low energy. Further, the trimethylene carbonate polymer can be directly returned to trimethylene carbonate by the depolymerization of the present invention. Trimethylene carbonate is extremely useful as a monomer for synthesizing functional and biodegradable polymers and as a synthetic intermediate in the fields of pharmaceutical base materials, cosmetics, and chemical products, and is a monomer suitable for enzyme polymerization. Furthermore, the hydrolase used to carry out the depolymerization has the advantage that it can be recovered and used repeatedly, in which case the activity of the enzyme is not substantially reduced. Thus, according to the present invention,
It has become possible to construct a completely recycle-type trimethylene carbonate polymer utilization system capable of reusing carbon resources with low energy consumption and low environmental load.

[0022]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The polytrimethylene carbonates of Examples 1 to 3 were prepared according to the method described in “Macromolecules 1997, 30,
3122 ". Example 1 Poly (trimethylene carbonate) (Mn = 4800
0, Mw / Mn = 3.5) (10 mg) was dissolved in acetonitrile (1 mL), and immobilized CA lipase (N
ovozym 435 (manufactured by Novo Nordisk Bioindustry) (120 mg) was added at 70 ° C. for 2 hours.
Stirring was performed for 4 hours. Add a small amount of chloroform to this,
The insoluble immobilized lipase was filtered off using celite, and the solvent was concentrated under reduced pressure from the filtrate using an evaporator to obtain trimethylene carbonate in a yield of 75%. The production was performed by silica gel column chromatography, and the following results were obtained. IR (KBr): 2943, 1468 (CH2). 1744, 1262 (carbonate
C = 0) cm-1. ¹ H-NMR (CDCl ₃ ); δ = 2.5 (quintet, 2H,
6.4), 4.2 (t, 4H, 6.1). ¹³ C-NMR (CDCl ₃ ): δ = 28.0
(CH ₃ CH ₂ CH ₃ ), 64.1 (CH ₂ O), 154.8 (C = 0). Elemental analysis; C, 47.36; H, 6.08%. Calculated value (C ₄ H
₆ O ₃ ): C, 47.06; H, 5.92%.

Example 2 Poly (trimethylene carbonate) (Mn = 4800)
0, Mw / Mn = 3.5) (10 mg) was dissolved in acetonitrile (3 mL), and immobilized CA lipase (N
ovozym 435, manufactured by Novo Nordisk Bioindustry Co., Ltd. (80 mg), and added at 70 ° C. for 72 hours.
Stirring was performed for hours. A small amount of chloroform was added thereto, and the insoluble immobilized lipase was separated by filtration using Celite, and the solvent was concentrated under reduced pressure from the filtrate using an evaporator to obtain trimethylene carbonate in a yield of 80%.

Example 3 Poly (trimethylene carbonate) (Mn = 6400,
(Mw / Mn = 1.9) (10 mg) was dissolved in acetonitrile (1 mL), and immobilized CA lipase (No.
vozym 435, Novo Nordisk Bioindustry Co., Ltd. (80 mg) was added, and the mixture was stirred at 40 ° C. for 24 hours. To this was added a small amount of chloroform, the insoluble immobilized lipase was separated by filtration using Celite, and the solvent was concentrated under reduced pressure from the filtrate using an evaporator to obtain trimethylene carbonate in a yield of 50%.

Example 4 The immobilized enzyme in Example 1 was recovered by filtration and dried in vacuum. Next, depolymerization was carried out in the same manner as in Example 1 using this enzyme, and trimethylene carbonate was recovered in a yield of 75%.

[0026]

According to the present invention, the trimethylene carbonate polymer is returned to trimethylene carbonate, which is a monomer suitable for enzyme polymerization, by a simple operation using one pot, under mild conditions, and with a method that has little adverse effect on the environment. be able to. Trimethylene carbonate monomers are extremely useful as monomers for synthesizing functional and biodegradable polymers, and as synthetic intermediates in the fields of pharmaceutical base materials, cosmetics, and chemical products. Furthermore, the hydrolase used for performing the depolymerization can be recovered and used repeatedly, without substantially reducing the activity as an enzyme. Therefore, according to the present invention, it has become possible to construct a completely-circulation-type utilization system of a trimethylene carbonate polymer that can consume low energy, reduce the burden on the environment, and reuse carbon resources.

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Claims (3)

[Claims] 1. A process for producing trimethylene carbonate, comprising depolymerizing a trimethylene carbonate polymer in the presence of a hydrolase. 2. The method for producing trimethylene carbonate according to claim 1, wherein the hydrolase is lipase. 3. The method for producing trimethylene carbonate according to claim 1, wherein the lipase is derived from Candida antarctica.