JP2001261814A - Process for polymerizing cyclic ether through ring opening - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an initiator that inhibits the termination and chain transfer mechanisms in the polymerization of a cyclic ether through ring opening and is therefor used for efficiently producing a high molecular-weight polymer having a narrow molecular weight distribution. SOLUTION: This is a process for producing a polymer by polymerizing a cyclic ether through ring opening, which process comprises using as the initiator a compound represented by general formula (I) (wherein X1 to X4 are each a substituent such as hydrogen, a halogen, nitro, or cyano, provided that at least one of X1 to X4 is a substituent selected from the group consisting of a halogen, nitro, and cyano; M is an atom such as boron or aluminum; Y1 and Y2 are each a substituent such as a halogen, an alkyl, or an aryl; and n is 0 or 1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polymer by ring-opening polymerization of a cyclic ether and an initiator for use in the method.

[0002]

2. Description of the Related Art Cationic, anionic, and coordinating anionic polymerizations are widely known as polymerization systems used in the ring-opening polymerization of cyclic ethers. The polymerization of these cyclic ethers has the problem that, except for some living polymerization systems, the formation of cyclic oligomers occurs, and when a monomer having a substituent is used, proton extraction is likely to occur. This is a polymerization system in which a problem that a polymer having a high molecular weight cannot be obtained or a molecular weight distribution is widened easily occurs.

In particular, it is known that the polymerization of tetrahydrofuran, which is a 5-membered ring, proceeds almost only by cationic polymerization, and furthermore, the above-mentioned phenomena are likely to occur, and it is difficult to control the molecular weight and terminal groups. ing. The polymerization of tetrahydrofuran, as an initiator, for example (such as HClO ₄₎ strong, strong acid anhydride _{((CF 3 SO 2) 2} O , etc.), triethyl oxonium ion (Et ₃ O ⁺ PbCl ₆ ^-, etc.), photolatent Initiators (p-Cl-Ph-N = N ⁺ PF ₅ ^- etc.) are used, but these known initiator systems are susceptible to chain transfer reaction and termination reaction, and have low molecular weight and wide molecular weight distribution. Only the polymer having it was obtained.

On the other hand, the boron-based initiator BF ₃ : THF-EO initiator system has high stability of a counter anion with respect to a polymerization active species, so that a termination reaction hardly occurs, and a polymer having a high molecular weight and a narrow molecular weight distribution can be obtained. Cheap. However, this polymerization system has a slow initiation reaction, and it is known that polymerization is not started unless oxiranes are added as a promoter, and there is a problem that homopolymerization hardly proceeds. As described above, an initiator system that satisfies requirements such as activity as an initiator, control of molecular weight, and narrow molecular weight distribution has not been developed at present.

[0005]

An object of the present invention is to produce a polymer by ring-opening polymerization of a cyclic ether.
It is to provide an initiator capable of efficiently producing a desired polymer. More specifically, it is an object of the present invention to provide an initiator for suppressing a termination mechanism or a chain transfer mechanism and efficiently producing a polymer having a high molecular weight and a narrow molecular weight distribution. Another object of the present invention is to provide a method for producing a polymer by ring-opening polymerization of a cyclic ether using an initiator having the above characteristics.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, by using a compound derived from a specific catechol as an initiator,
It has been found that a desired polymer can be produced by efficiently polymerizing a cyclic ether. The present invention has been completed based on the above findings.

That is, the present invention relates to a method for producing a polymer by ring-opening polymerization of a cyclic ether, comprising the following general formula:
(I):

Embedded image (Wherein X ¹ , X ² , X ³ , and X ⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted arylalkyl group A substituent selected from the group consisting of X ¹ , X ² , X ³ , and X ⁴
One is a substituent selected from the group consisting of halogen, nitro, and cyano; M is an atom selected from the group consisting of boron, aluminum, titanium, and zirconium; Y ¹ and Y ² is each independently a hydrogen atom, a halogen atom, an alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted arylalkyl group, an alkoxy group, a substituted or unsubstituted arylalkyloxy group, a substituted or unsubstituted aryloxy group, Or a substituent selected from the group consisting of a dialkylamino group, a substituted or unsubstituted arylamino group, an alkylthio group, and a substituted or unsubstituted arylthio group; n represents 0 or 1)
The use of a compound represented by the formula (I) as an initiator is provided.

According to a preferred embodiment of the present invention, there is provided the above method, wherein M is a boron atom. In another aspect, the present invention provides an initiator for producing a polymer by ring-opening polymerization of a cyclic ether, the initiator including the compound represented by the general formula (I). Is done.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The terms used in the present specification have the following meanings. The alkyl moiety of an alkyl group or a substituent having an alkyl moiety (eg, an alkylaryl group, an alkoxy group, an alkylthio group, etc.)
It may be linear, branched, cyclic, or a combination thereof, and has 1 to 12, preferably 1 to 10, more preferably 1 to 8, more preferably 1 to 6, particularly preferably 1 to 6, carbon atoms. It is about 1 to 4. Examples of the alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a cyclopropyl group, a n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group,
Examples thereof include a cyclobutyl group, a cyclopropylmethyl group, an n-pentyl group, and an n-hexyl group.
It is not limited to these.

The halogen atom may be any of a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, but is preferably a fluorine atom, a chlorine atom or a bromine atom. When "substituted or unsubstituted" is used for the aryl moiety of an aryl group or a substituent having an aryl moiety (eg, an arylalkyl group), the aryl ring may have one or more substituents on the ring. Means that. The position of the substituent present on the aryl ring is not particularly limited, and when two or more substituents are present,
They may be the same or different. Examples of the aryl group include a phenyl group or a naphthyl group, and more preferably a phenyl group.

[0011] Examples of the substituted aryl group include an alkyl-substituted aryl group, more preferably an alkyl-substituted phenyl group. More specifically, examples of the substituted aryl group include a p-toluyl group, a p-ethylphenyl group, and a xylyl group. Examples of the arylalkyl group include a benzyl group, a phenethyl group, and a naphthylmethyl group, and a benzyl group is preferable.

M is an atom selected from a boron atom, an aluminum atom, a titanium atom, and a zirconium atom, and is preferably a boron atom. n represents 0 or 1 depending on the valence of the metal represented by M. Examples of the alkoxy group represented by Y ¹ or Y ² include a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group.
Examples of the arylalkyloxy group include a benzyloxy group, and examples of the aryloxy group include a phenoxy group. Examples of the mono or dialkylamino group represented by Y ¹ or Y ² include a monomethylamino group, a dimethylamino group, a monoethylamino group, an ethylmethylamino group, a mono-n-propylamino group, and the like. When they have groups, they may be the same or different. The arylamino group represented by Y ¹ or Y ² includes a phenylamino group, the alkylthio group includes a methylthio group and an ethylthio group, and the arylthio group includes a phenylthio group. As Y ¹ or Y ² , an alkoxy group such as a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an aryloxy group such as a phenoxy group, or an arylalkyl group such as a benzyl group is preferable. Further, Y ¹ and Y ² are preferably groups other than a hydrogen atom.

Specific examples of the compound represented by the general formula (I) include, for example, 3,4,5,6-tetrafluorocatecholborane, 3,4,5-trifluorocatecholborane, 3,4 6-trifluorocatechol borane,
3,4-difluorocatechol borane, 3,5-difluorocatechol borane, 3,6-difluorocatechol borane, 3-fluorocatechol borane, 4-fluorocatechol borane, and a fluorine atom (in these compounds, two or more fluorine atoms Compounds in which some or all of them have been replaced by chlorine or bromine atoms if present);

3,4,5,6-tetrachlorocatecholbutoxyborane, 3,4,5-trichlorocatecholbutoxyborane, 3,4,6-trichlorocatecholbutoxyborane, 3,4-dichlorocatecholbutoxyborane, 3, 5-dichlorocatechol butoxyborane, 3,
6-dichlorocatecholbutoxyborane, 3-chlorocatecholbutoxyborane, 4-chlorocatecholbutoxyborane, and the fluorine atom (part or all of them when two or more chlorine atoms are present) of these compounds A compound in which a butoxy group is replaced by an alkoxy group, an alkylamino group, or an alkylthio group;

3,4,5,6-tetracyanocatechol borane, 3,4,5-tricyanocatechol borane,
3,4,6-tricyanocatechol borane, 3,4-dicyanocatechol borane, 3,5-dicyanocatechol borane, 3,6-dicyanocatechol borane, 3-cyanocatechol borane, 4-cyanocatechol borane, and these A compound in which a hydrogen atom on a boron atom of a compound is replaced with an alkyl group, an alkoxy group, an alkylamino group, or an alkylthio group;

3,4,5,6-tetranitrocatecholborane, 3,4,5-trinitrocatecholborane,
3,4,6-trinitrocatechol borane, 3,4-dinitrocatechol borane, 3,5-dinitrocatechol borane, 3,6-dinitrocatechol borane, 3-nitrocatechol borane, 4-nitrocatechol borane, and these A compound in which a hydrogen atom on a boron atom of a compound is replaced with an alkyl group, an alkoxy group, an alkylamino group, or an alkylthio group; and a compound in which the boron atom of all the above compounds is replaced with an aluminum atom, a titanium atom, or a zirconium atom And the like.

Of these, preferred are tetrachlorocatechol borane and its alkoxy derivative, and tetrabromocatechol borane and its alkoxy derivative. However, the compound represented by the general formula (I) is not limited to the compounds exemplified above.

The compound represented by the above general formula (I) can be produced, for example, by reacting catechol with a corresponding metal hydride, alkoxy compound, amide compound or alkylthio compound. Specific examples thereof are specifically shown in Examples of the present specification, and those skilled in the art refer to the methods described in the Examples, and by appropriately selecting starting compounds, reaction reagents, reaction conditions, and the like, The above general formula (I)
Can be produced.

The compound represented by the above general formula (I) may have one or more asymmetric carbon atoms depending on the type of the substituent, and the stereoisomer such as an optically active substance or a diastereoisomer may be present. May be present. As the initiator of the present invention, in addition to stereoisomers in a pure form, any substance such as an arbitrary mixture of stereoisomers and a racemate may be used.
When the compound represented by the general formula (I) forms a salt, a substance in the form of a salt may be used as the initiator. In addition, a hydrate or a solvate of the compound represented by the above general formula (I) or a salt thereof can also be used as an initiator.

The initiator of the present invention is used as an initiator for producing a polymer by ring-opening polymerization of a cyclic ether monomer. As the cyclic ether monomer, a 3- to 11-membered cyclic ether containing one oxygen atom as a ring-constituting atom can be used. On the carbon atoms that make up the ring,
One or more substituents may be present, and when having two or more substituents, they may be the same or different. Examples of the substituent on the ring include, for example, one having 1 to carbon atoms.
12 alkyl groups (methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t
-Butyl group, hexyl group, etc.), halogen-substituted alkyl group having 1 to 20 carbon atoms (eg, chloromethyl group, bromomethyl group, chloroethyl group, etc.), aryl group (phenyl group, etc.), arylalkyl group (benzyl group, etc.) ,
Alkylaryl group (tolyl group, etc.), aryloxy group (phenoxy group, etc.), halogen atom, alkoxy group (methoxy group, ethoxy group, propoxy group, etc.), dialkylamino group (dimethylamino group, diethylamino, etc.), cyano group, etc. Can be mentioned.

Specific examples of the cyclic ether monomer include ethylene oxide, propylene oxide, isobutylene oxide, cis-1,2-butylene oxide, trans-1,2-butylene oxide, styrene oxide,
Cyclopentene oxide, cyclohexene oxide, epichlorohydrin, glycidol, glycidyl phenyl ether, oxetane, 2-methyloxetane, 2,2
-Dimethyl oxetane, 2-chloromethyl oxetane,
3,3-dimethyloxetane, 3-methyl-3-chloromethyloxetane, 3,3-bis (chloromethyl) oxetane, 3- (trimethylsilyloxymethyl) oxetane, tetrahydrofuran, 2-methyl-tetrahydrofuran, 3-methyl-tetrahydrofuran 2,5-dimethoxytetrahydrofuran, 2-ethoxytetrahydrofuran, methyltetrahydrofurfuryl ether,
2,3-dihydrobenzofuran, 2,3-dihydrofuran, 2,5-dihydrofuran, tetrahydrofuran acetic acid ethyl ester, tetrahydrofurfuryl chloride, tetrahydrofurfuryl acetate, tetrahydrofurfuryl propionate, tetrahydrofurfuryl n- Butyrate, tetrahydrofurfuryl methacrylate and the like can be mentioned. Of these, ethylene oxide, propylene oxide, oxetane, and tetrahydrofuran are preferred. One kind of the cyclic ether monomer may be used alone, or two or more kinds of the cyclic ether monomers may be copolymerized. In particular, when a cyclic ether monomer having low polymerization activity such as tetrahydrofuran is polymerized, it is desirable to add a cyclic ether compound having a large strain as a promoter.

The ring-opening polymerization method in the present invention is not particularly limited, and may be any of conventional polymerization methods such as slurry polymerization, gas-phase polymerization, bulk polymerization, solution polymerization and suspension polymerization. May be used. Of these,
Slurry polymerization, solution polymerization and bulk polymerization are preferred. Further, a batch method or a continuous method may be used. Formula of the present invention
The method for introducing the initiator represented by (I) into the polymerization system is not particularly limited, and an appropriate method can be adopted depending on the purpose. For example, the initiator may be added in the presence and / or absence of a monomer. Alternatively, the compound of formula (I)
May be introduced into the polymerization system to introduce a raw material compound for producing the compound represented by the formula (1). In that case,
The order of the raw material compounds added to the polymerization system is not particularly limited. Usually, starting compounds for producing the initiator (usually catechols and metal hydrides, alkoxy compounds,
An initiator can be generated in a polymerization system by introducing an amide compound, an alkylthio compound, etc.) into an inert solvent under an inert gas atmosphere and bringing the starting compounds into contact with each other.

The polymerization temperature can be appropriately selected, but is usually in the range of -78 to 150 ° C, preferably -30 to 110 ° C. The amount of the initiator used is not particularly limited, and can be appropriately selected according to various conditions such as the type of the cyclic ether monomer, the type of the reaction, the reaction temperature, and the polymerization time. For example, in the case of a solution polymerization system, the range is preferably 10 ^-6 to 10 mol / l, particularly preferably 10 ^-4 to 1 mol / l.
The ratio of the initiator to the monomer is, for example, 1 to 1/10.
⁶ , preferably in the range of 1-1 / 10 ⁵ .

In the case of polymerization using a polymerization solvent, a solvent usually used for ring-opening polymerization can be used.
Halogenated hydrocarbons such as methylene chloride and 1,2-dichloroethane; aliphatic hydrocarbons such as pentane, hexane, heptane and octane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; and aromatics such as benzene, toluene and xylene Petroleum fractions such as hydrocarbons, gasoline, kerosene, light oil, etc.
Further, a mixed solvent thereof can be used.

The molecular weight of the polymer can be controlled by appropriately selecting various conditions such as the type of initiator, the type of cyclic ether monomer, the type of reaction, the reaction temperature, and the polymerization time. The polymerization degree (n) of the polymer obtained by the ring-opening polymerization method of the present invention is usually from 10 to 3000. The polymer obtained by the method of the present invention has a feature that the molecular weight distribution is narrow. For example, when ring-opening polymerization of tetrahydrofuran is performed, the ratio Mw / Mn (= Q value) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) is 1.0 to 3.5, preferably 1.0 to 3.5. It is possible to produce about 2.5 polymers.

[0026]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the scope of the present invention is not limited to the following examples. In the examples, Mw and Mw / Mn are as follows:
It was calculated by permeation chromatography (GPC) in terms of polystyrene using tetrahydrofuran (THF) as a solvent. The identification of the borane compound is performed by mass spectrometry (MS: TSQ-manufactured by Finnigan Mat).
700 measured). The terminal groups were quantified by dissolving the sample in CDCl ₃ and analyzing the NMR spectrum (2
70 MHz, measured by JEOL Ltd.).

Example 1: Synthesis of tetrachlorocatechol borane 0.62 g (2.5 mmol) of tetrachlorocatechol was placed in a two-necked eggplant flask purged with nitrogen, and toluene 20 was added.
Dissolved in ml. Borane dimethyl sulfide 0.24
ml (2.5 mmol) and add 110 with stirring.
Heated to ° C. The solvent was distilled off under reduced pressure to obtain 0.64 g of white solid tetrachlorocatechol borane. As a result of mass spectrometry, molecular ion peak m / z: 256 (M
⁺・) Was observed.

Example 2: Synthesis of tetrachlorocatechol butoxyborane 0.62 g (2.5 mmol) of tetrachlorocatechol was placed in a two-necked eggplant flask purged with nitrogen, and toluene was added.
Dissolved in ml. 0.58 g of tributoxy borane (2.
(5 mmol) was added and reacted, and toluene was distilled. The remaining toluene was distilled off under reduced pressure to obtain 0.83 g of light yellow solid tetrachlorocatechol borane (2.
5 mmol). As a result of mass spectrometry, a molecular ion peak m / z: 328 (M ⁺ ·) was observed.

Example 3 Synthesis of tetrachlorocatechol isopropoxyborane Tetrachlorocatechol borane synthesized in Example 1 0.64
g (2.5 mmol) was placed in a two-necked eggplant flask purged with nitrogen, and dissolved in 20 ml of toluene. 0.15 ml (2.5 mmol) of isopropanol was added to this solution to cause a reaction. After reacting for 24 hours, toluene was distilled off under reduced pressure to obtain 0.79 g (2.5 mmol) of white solid tetrachlorocatechol isopropoxyborane. As a result of mass spectrometry, molecular ion peak m / z: 314
(M ⁺ ·) was observed.

Example 4: Synthesis of tetrachlorocatechol phenoxyborane 0.24 g of phenol instead of isopropanol
0.87 g (2.5 mmol) of white solid tetrachlorocatechol borane was obtained in the same manner as in Example 3 except that (2.5 mmol) was used in Example 3. As a result of mass spectrometry,
A molecular ion peak m / z: 348 (M ⁺ ·) was observed.

Example 5 0.1 mmol of tetrachlorocatechol butoxyborane synthesized in Example 1 was placed in a two-necked flask, and after purging with nitrogen, 9.3 ml of dehydrated methylene chloride was added and dissolved. 0.98 g of cyclohexene oxide (10 m
mol) was added to start polymerization, and stirring was continued for 1 hour while maintaining the temperature at room temperature, and 1 ml of water was added to stop the polymerization. After adding 2N NaOH to the reaction mixture and stirring, the methylene chloride layer was passed through a column of ₂ g of Al ₂ O ₃ and the solvent was distilled off under reduced pressure to obtain a polymer. Yield 1.0 g (100% conversion),
Mn = 13200, Mw / Mn = 1.92

Example 6: Polymerization was carried out in the same manner as in Example 5 except that 0.58 g (10 ml) of oxetane was used instead of cyclohexene oxide. Yield 0.46 g (78% conversion), Mn = 2500, M
w / Mn = 1.73

Example 7 0.62 g (2.5 mmol) of tetrachlorocatechol
Into a two-necked flask, purged with nitrogen, and dehydrated THF 17.7.
ml was added to dissolve. Borane-THF complex / THF
2.3 ml (2.5 mmol) of the solution (1.07 M) was added to initiate polymerization. Stirring was continued for 1 hour while maintaining the reaction mixture at room temperature, and 10 ml of water was added to terminate the polymerization.
The reaction mixture was dissolved in 400 ml of ether, and 0.02
2 times with 50 ml of 5N NaOH aqueous solution and 2 times with 50 ml of water
It was washed with 0.01N HCl aqueous solution twice and the solvent was distilled off under reduced pressure to obtain a polymer. Yield 11.5 g (conversion 65%), Mn = 65100,
Mw / Mn = 1.79 As for the terminal structure, 5% or less of butoxy groups existed per 1 molecule of the polymer, and other than that, no identification was possible.

Example 8 Polymerization was carried out in the same manner as in Example 5 except that tetrabromocatechol was used instead of tetrachlorocatechol. Yield 10.9 g (conversion 62%), Mn = 32330,
Mw / Mn = 1.80 In the terminal structure, 5% or less of butoxy groups existed per one molecule of the polymer.

Example 9 Tetrachlorocatechol borane synthesized in Example 1 2.5 m
mol was placed in a two-necked flask and purged with nitrogen. At room temperature, THF (20 ml, 246 mmol) was added to initiate polymerization. The resulting polymer was purified as in Example 5. Yield 12.3 g (conversion 69%), Mn = 42600,
Mw / Mn = 1.84 The terminal structure contained not more than 5% of a butoxy group per one molecule of the polymer, and other compounds could not be identified. Example 10 Instead of tetrachlorocatechol borane, tetrachlorocatechol butoxyborane synthesized in Example 2 (2.5 mm
ol) was carried out in the same manner as in Example 9 except that the polymerization was carried out. Yield 11.6 g (conversion 65%), Mn = 42700,
Mw / Mn = 1.87 The terminal structure had 100% butoxy groups per polymer molecule.

Example 11 Instead of tetrachlorocatechol borane, tetrachlorocatechol isopropoxy borane synthesized in Example 3 (2.
Polymerization was carried out in the same manner as in Example 9 except that 5 mmol) was used. Yield 11.9 g (conversion 67%), Mn = 41600,
Mw / Mn = 1.74 The terminal structure had 90% of isopropoxy groups per polymer molecule. Example 12 Instead of tetrachlorocatechol borane, tetrachlorocatechol phenoxy borane synthesized in Example 4 (2.5 m
mol) was used in the same manner as in Example 9. Yield 12.9 g (conversion 73%), Mn = 39200,
Mw / Mn = 1.94 The terminal structure had 100% of phenoxy groups per polymer molecule.

Example 13 (Comparative Example) Polymerization was carried out in the same manner as in Example 5 except that catechol was used instead of tetrachlorocatechol, but the polymerization did not proceed.

[0038]

By polymerizing a cyclic ether using the initiator of the present invention, a polymer having a high molecular weight and a narrow molecular weight distribution can be efficiently produced.

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Claims (3)

[Claims] 1. A method for producing a polymer by ring-opening polymerization of a cyclic ether, comprising the following general formula (I): (Wherein X ¹ , X ² , X ³ , and X ⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted arylalkyl group A substituent selected from the group consisting of X ¹ , X ² , X ³ , and X ⁴
One is a substituent selected from the group consisting of halogen, nitro, and cyano; M is an atom selected from the group consisting of boron, aluminum, titanium, and zirconium; Y ¹ and Y ² is each independently a hydrogen atom, a halogen atom, an alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted arylalkyl group, an alkoxy group, a substituted or unsubstituted arylalkyloxy group, a substituted or unsubstituted aryloxy group, Or a substituent selected from the group consisting of a dialkylamino group, a substituted or unsubstituted arylamino group, an alkylthio group, and a substituted or unsubstituted arylthio group; n represents 0 or 1)
A method characterized by using a compound represented by the formula as an initiator. 2. The method according to claim 1, wherein M is a boron atom. 3. An initiator for producing a polymer by ring-opening polymerization of a cyclic ether, wherein the initiator is a compound represented by the general formula of claim 1.
An initiator containing the compound represented by (I).