JP4840851B2 - Method for producing polyester from oxetane compound, γ-lactone and carbon monoxide - Google Patents

Description

  The present invention relates to a method for producing polyesters having an ester structure by polymerizing an oxetane compound, γ-lactone and carbon monoxide.

Japanese Patent No. 2713108 JP2003-137988 WO03 / 50154 Publication Yoshiharu Toi: “Biodegradable Plastic Handbook”, NTS (1995). p.202-279 Yutaka Tokiwa: Future Materials, 1 (6), 23 (2001) Hideki Sakurai et al .: “Organic synthesis using bird transition metals”, Yodogawa Shoten (1971). p.140-227

  Polyesters such as aliphatic polyesters and poly (ester-ethers) have recently attracted attention as biodegradable polymers. Examples of the aliphatic polyester chemically synthesized include polylactic acid, polycaprolactone, and polybutylene succinate. As described in Non-Patent Document 1 (p.279), polylactic acid is obtained by chemically dehydrating polycondensation reaction of lactic acid produced by fermenting sugar glucose with lactic acid bacteria. Polycaprolactone is synthesized by ring-opening polymerization of ε-caprolactone as described in Non-Patent Document 2. As for polybutylene succinate, a method for producing polybutylene succinate by reaction of succinic acid and 1,4-butanediol has been developed as described in Patent Document 1.

  Poly (3-hydroxybutyric acid) is known as a biodegradable polymer produced by microorganisms. As described in Non-Patent Document 1 (p.252), chemical synthesis of poly (3-hydroxybutyric acid) by ring-opening polymerization of β-lactone is also being studied. In addition, a method for producing poly (3-hydroxybutyric acid) by a reaction of polymerizing propylene oxide and carbon monoxide in the presence of a transition metal complex as described in Patent Document 2 has been studied.

  On the other hand, as described in Non-Patent Document 1 (p. 202), poly (4-hydroxybutyrate) is also expected as a polymer exhibiting biodegradability, but it is difficult to perform ring-opening polymerization of the corresponding γ-lactone. As described in Non-Patent Document 1 (p.253), under high temperature and high pressure (160 ° C., 20000 atm), in the presence of glycolic acid or lactic acid, or under limited conditions such as copolymerization with a four-membered lactone. There are only examples of synthesis.

  As for poly (ester-ether), a polymer obtained by ring-opening polymerization of 1,4-dioxan-2-one is known as a biodegradable polymer as described in Non-Patent Document 1 (p.254). Although Patent Document 3 describes a reaction between an oxetane compound and carbon monoxide, there is no teaching of obtaining polyesters.

  The inventors of the 85th Annual Meeting of the Chemical Society of Japan, No. 2B7-28 “Copolymerization of Oxetane and Carbon Monoxide Using Cobalt Catalyst” and Lecture No. 1Pg025 at the 54th Annual Meeting of the Society of Polymer Science, Japan In "Copolymerization of Cyclic Ethers and Carbon Monoxide with Cobalt Catalyst", we reported new polyesters by oxetane and carbon monoxide copolymerization and their production methods. Although this production method is a novel method for synthesizing polyesters, it is sometimes difficult to sufficiently increase the molecular weight.

  The present invention is to provide a method for synthesizing such polyesters from an oxetane compound and γ-lactone carbon monoxide. These polyesters are polyesters having a structure similar to a polymer obtained from γ-lactone, and are expected to be used as biodegradable polymers by increasing the molecular weight.

  As a result of intensive studies to solve the above problems, the present inventors have found that an oxetane compound, γ-lactone, and carbon monoxide in the presence of a carbonylation catalyst or in the presence of a carbonylation catalyst, a basic compound, and an alkyl halide. The present inventors have found that polyesters can be efficiently produced by polymerizing the polymer, and thus completed the present invention.

（式中、R1〜R8はハロゲン、H、アルキル基、アラルキル基、アルコキシメチル基、ヒドロキシメチル基又はアリール基を示し、ｘ及びｙは存在割合を示し、ｘ+ｚは10〜100モル％、ｙは0〜90モル％の範囲である） That is, the present invention is a method for producing a polyester represented by the following formula (1), wherein an oxetane compound, γ-lactone and carbon monoxide are polymerized in the presence of a carbonylation catalyst.

(Wherein R1 to R8 represent a halogen, H, an alkyl group, an aralkyl group, an alkoxymethyl group, a hydroxymethyl group or an aryl group, x and y represent an abundance ratio, x + z is 10 to 100 mol%, y is in the range of 0 to 90 mol%)

  These polyesters can be polyesters wherein x + z is 100 mol% in the formula (1), and ether structures in which y is 1 mol% or more, preferably 10 to 90 mol% in the formula (1) Polyester having

  In this polyester production method, 1) a basic compound and an alkyl halide are present, 2) the carbonylation catalyst is a cobalt carbonyl complex, 3) the basic compound is a nitrogen atom-containing compound, 4 It is preferable to satisfy one or more of either 1) the basic compound is a phenanthroline derivative or 6) the alkyl halide is benzyl bromide.

Under this reaction condition, polymerization does not proceed with γ-lactone alone, and it is difficult to obtain a high molecular weight polyester by the reaction of oxetane compound and carbon monoxide.

  The polyesters of the present invention are represented by the above formula (1). In the formula (1), R1 to R8 represent a halogen, H, an alkyl group, an aralkyl group, an alkoxymethyl group, a hydroxymethyl group or an aryl group, preferably hydrogen or an alkyl group having 1 to 3 carbon atoms. R1 to R8 may be the same or different.

  x, y, and z represent abundance, x + z ranges from 10 to 100 mol%, and y ranges from 0 to 90 mol%. Hereinafter, the structural units whose existence ratio is x, y, and z are referred to as structural units x, y, and z, respectively. When x + z is 100 mol%, the polyesters of the present invention are polymers composed only of polyester structural units (excluding terminals). On the other hand, when having the structural unit y, when y is usually 1 mol% or more, polyesters having an ether structure, that is, poly (ether-ester). The polyesters referred to in the present invention are understood to include both polyesters having an ether structure and polyesters having no ether structure. In the case of polyesters having an ether structure, the molar ratio of x + z and y is in the range of 10 to 90:90 to 10, preferably 30 to 70:70 to 30. The structural units x and z are the same structural unit if R5 to R8 in the structural unit x are H, and R3 to R4 and R1 to R2 in the structural unit z are the same.

  The molecular weight of the polyesters of the present invention is not limited, but the number average molecular weight Mn is preferably in the range of 5,000 to 500,000, and more preferably in the range of 10,000 to 300,000 when molded and used as a biodegradable polymer. .

（式中、R1〜R8、ｘ、ｙ、ｚは、式（１）と同じである） The method for producing polyesters of the present invention comprises polymerizing an oxetane compound, γ-lactone and carbon monoxide in the presence of a carbonylation catalyst as shown in reaction formula (2).

(In the formula, R1 to R8, x, y, and z are the same as those in the formula (1)).

  The oxetane compound used in this polymerization reaction can be used as long as the compound has an oxetanyl group, but is generally a 3-position substituted oxetane compound shown in the reaction formula (2). Preferably, the substituent has a halogen, an alkyl group, an aralkyl group, an alkoxymethyl group, a hydroxymethyl group, or an aryl group, and more preferably, R1 and R2 are independently H from the viewpoint of biodegradability. , An oxetane compound which is an alkyl group, an alkoxymethyl group or a hydroxymethyl group. Both R1 and R2 may be H.

  The γ-lactone used in this polymerization reaction can be used as long as it has a γ-lactone ring, but is generally γ-lactone shown in the reaction formula (2). Preferably, it has a halogen, an alkyl group, an aralkyl group, an alkoxymethyl group, a hydroxymethyl group, or an aryl group as a substituent, and more preferably, R3 to R6 are independently H from the viewpoint of biodegradability. Γ-lactone which is an alkyl group, an alkoxymethyl group or a hydroxymethyl group.

As the carbonylation catalyst used for polymerizing the oxetane compound and carbon monoxide, a known carbonylation catalyst as described in Non-Patent Document 3 can be used, and preferably represented by the formula (3) [( salph) Al (THF) ₂ ] [Co (CO) ₄ ], cobalt complexes such as dicobalt octacarbonyl and cobalt acetylacetonate, ruthenium media such as triruthenium dodecacarbonyl, rhodium complexes such as hexarhodium hexadecacarbonyl, nitrogen Although palladium complexes, such as an atomic ligand containing palladium complex and a phosphorus element ligand containing paradium complex, are mentioned, A cobalt complex is most preferable.

  The amount of the carbonylation catalyst used is 0.1 to 10 mol, preferably 0.3 to 5 mol, relative to 100 mol of the oxetane compound. If it is less than 0.1 mol, the reaction rate is low, which is industrially disadvantageous, and even if a catalyst exceeding 10 mol is used, the yield and molecular weight are hardly improved, and an effect commensurate with the amount of catalyst used cannot be obtained.

  In the above polymerization reaction, in order to further activate the polymerization reaction, it is also advantageous to add a basic compound and an alkyl halide in addition to the carbonylation catalyst.

Examples of basic compounds used here include pyridine, 2,2′-bipyridine, 1,10-phenanthroline, 6,7-dihydro-5,8-dimethyldibenzo [b, j] -1,10-phenanthroline (hereinafter, A compound containing nitrogen atoms such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, more preferably 1,10-phenanthroline, DDDP, 2,9-dimethyl-4, Phenanthroline derivatives such as 7-diphenyl-1,10-phenanthroline.
Although the action of the basic compound is not clear, it acts as a ligand. For example, when dicobalt octacarbonyl is used as a catalyst, [(ligand) Co (CO) ₃ ] ⁺ [Co (CO) ₄ ] ⁻ complex is formed, and the [(ligand) Co (CO) ₃ ] ⁺ species in this complex is considered to promote the ring opening of oxetane and the formation of polyester.

Moreover, as an alkyl halide used here, although not limited, methyl iodide, benzyl bromide, etc. can be used. More preferred is benzyl bromide.
Although the action of alkyl halide is not clear, for example, when benzyl bromide is used as the alkyl halide and dicobalt octacarbonyl is used as the catalyst, a complex of PhCH ₂ COCo (CO) ₄ is formed in the system, and oxetane is sequentially formed. It is considered that the polyesters of the present invention are formed via an intermediate represented by the formula (4) in which carbon monoxide or γ-lactone is reacted, and the molecular weight is protected by the terminal being an ester group. The yield is estimated to be improved.

  The usage-amount of an alkyl halide is 0.1-5 times mole with respect to a carbonylation catalyst, Preferably it is 0.5-2 times mole. When the amount is less than 0.1 times mol, the activation effect is low, and even when a catalyst exceeding 5 times mol is used, the activation improvement effect is small and an effect commensurate with the amount used cannot be obtained.

  The usage-amount of (gamma) -lactone is 0.1-5 times mole with respect to an oxetane compound, Preferably it is 0.5-2 times mole. If it is less than 0.1-fold mol, the effect of improving the molecular weight is low, and even if a catalyst of more than 5-fold mol is used, the effect of improving the molecular weight is small and an effect commensurate with the amount used cannot be obtained.

  The pressure of carbon monoxide used in the polymerization reaction is preferably in the range of about 0.1 to 10 MPa, and preferably in the range of 4 to 8 MPa. The molar ratio of the raw material oxetane compound and carbon monoxide is usually a large excess of carbon monoxide, the carbon monoxide pressure is maintained in the above range during the reaction, and unreacted carbon monoxide is separated after the reaction is completed. The method is preferred.

  The polymerization reaction temperature is in the range of room temperature to about 150 ° C, and particularly preferably about 80 ° C to 120 ° C. When the reaction temperature is lower than room temperature, the reaction rate is low, which is industrially disadvantageous. When it exceeds 150 ° C., the molecular weight is lowered, which is disadvantageous. Therefore, a polyester having a molecular weight of 10,000 or more can be easily obtained by performing the reaction at a relatively low temperature.

  The polymerization reaction can be carried out without a solvent, but a solvent can also be used. Examples of the solvent include aromatic compounds such as benzene and toluene, ether solvents such as diethyl ether, tetrahydrofuran (THF) and diethylene glycol dimethyl ether, and halogenated solvents such as methylene chloride and chlorobenzene, or a mixed solvent of two or more. Can be used as

  The polymerization reaction can be carried out by any of batch, semi-batch and continuous methods. After completion of the reaction, the target polyester is separated from the solvent, catalyst, unreacted raw material and the like, and further purified if necessary.

  Polyesters obtained by the production method of the present invention are polyesters having a structure similar to that of a copolymer of oxetane and γ-lactone, and are considered to have biodegradability, and are used as biodegradable polymers. I can expect. Since the method for producing polyesters of the present invention uses an oxetane compound, γ-lactone and carbon monoxide as raw materials, various polyesters having different substituents can be easily produced.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

Example 1
In a 20 mL Schlenk tube reactor under argon gas atmosphere, dicobalt octacarbonyl catalyst (12.2 mg, 0.036 mmol), benzyl bromide (4.5 μL, 0.038 mmol), DDDP (11.5 mg, 0.037 mmol), oxetane (0.58 mL) 8.9 mmol) and γ-butyrolactone (0.76 ml, 9.9 mmol) were added and freeze degassed. This solution was transferred to a pressure resistant reaction vessel under an argon gas atmosphere, carbon monoxide (6.0 MPa) was injected under pressure, and the mixture was heated and stirred at 100 ° C. for 20 hours. After completion of the reaction, the reaction solution was cooled to room temperature to remove carbon monoxide, and the crude product was transferred to a round bottom flask using chloroform. Concentrated hydrochloric acid (0.1 mL) was added to the crude product, and the mixture was stirred for 30 minutes, dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated and vacuum dried to obtain 325 mg of a highly viscous oily copolymer (polyether polyester; Mn = 15000, Mw / Mn = 2.0, ester / ether ratio = 50/50). Yield 51% (based on oxetane).

  This reaction corresponds to a reaction in which all of R1 to R8 are H in the reaction formula (2), and the structural units X and Z are the same.

  The reaction was performed in the same manner as in Example 1 except that the amount of the reaction raw material was changed as shown in Table 1. The results are shown in Table 1. Runs 1 and 2 are comparative examples.

Example 2
In a 20 mL Schlenk tube reactor under argon gas atmosphere, dicobalt octacarbonyl catalyst (11.1 mg, 0.033 mmol), benzyl bromide (3.9 μL, 0.032 mmol), DDDP (10.1 mg, 0.033 mmol), oxetane (0.54 mL) , 8.3 mmol) and γ-valerolactone (1.0 ml, 10.5 mmol) were added and freeze degassed. This solution was transferred to a pressure resistant reaction vessel under an argon gas atmosphere, carbon monoxide (6.0 MPa) was injected under pressure, and the mixture was heated and stirred at 100 ° C. for 20 hours. After completion of the reaction, the reaction solution was cooled to room temperature to remove carbon monoxide, and the crude product was transferred to a round bottom flask using chloroform. Concentrated hydrochloric acid (0.1 mL) was added to the crude product, and the mixture was stirred for 30 minutes, dried over anhydrous magnesium sulfate, and filtered. Concentrate the filtrate and dry in vacuo to obtain 305 mg of highly viscous oily copolymer (Formula 5) (polyether polyester; Mn = 3400, Mw / Mn = 2.5, x / y / z = 19/56/25) Obtained. Yield 41% (based on oxetane). The reaction formula is shown in Formula (5).

Comparative Example 1
In a 20 mL Schlenk tube reactor under argon gas atmosphere, dicobalt octacarbonyl (12 mg, 0.035 mmol), benzyl bromide (4.2 mL, 0.035 mmol), DDDP (0.035 mmol), 3-methyl-3-methoxy Methyl oxetane (1.16 mL, 10 mmol) was added and freeze degassed. This solution was transferred to a pressure resistant reaction vessel under an argon gas atmosphere, carbon monoxide (6.0 MPa) was injected under pressure, and the mixture was heated and stirred at 100 ° C. for 20 hours. After completion of the reaction, separation, concentration and drying were carried out in the same manner as in Example 1 to obtain a copolymer (polyether polyester; Mn = 3,100, Mw / Mn = 2.0, ester / ether ratio 0.43).

  This reaction corresponds to a reaction in which R1 is methyl and R2 is methoxy in the reaction formula (2) and γ-lactone is not used as a raw material. Therefore, the structural unit x in the formula (1) does not exist.

¹ H-NMR spectrum of the polyether polyester obtained in Example 1.

Claims (6)

A method for producing a polyester represented by the following formula (1), wherein an oxetane compound, γ-lactone and carbon monoxide are polymerized in the presence of a carbonylation catalyst.

(Wherein R1 to R8 represent a halogen, H, an alkyl group, an aralkyl group, an alkoxymethyl group, a hydroxymethyl group or an aryl group, x, y and z represent the abundance, and x + z represents 10 to 100 mol. % And y are in the range of 0 to 90 mol%)   The method for producing a polyester according to claim 1, wherein a basic compound and an alkyl halide are present in addition to the carbonylation catalyst.   The method for producing a polyester according to claim 1 or 2, wherein the carbonylation catalyst is a cobalt carbonyl complex.   The method for producing a polyester according to claim 2, wherein the basic compound is a nitrogen atom-containing compound.   The method for producing a polyester according to claim 2, wherein the basic compound is a phenanthroline derivative.   The method for producing a polyester according to any one of claims 2 to 5, wherein the alkyl halide is benzyl bromide.

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