JP2005298778A - Ring-opening polymerization of oxetane derivative using aluminum compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyoxetane having higher molecular weight than conventional one, its production process and an initiator used in the process. <P>SOLUTION: A polyether composed of a recurring unit expressed by formula (1) [where R<SP>1</SP>represents substituted or unsubstututed 1-3C alkyl group; X represents a halogen atom or a group expressed by formula(a): -O-R<SP>2</SP>(R<SP>2</SP>represents an organic group)] and having a number-average molecular weight Mn measured by size exclusion chromatography of 3.5×10<SP>4</SP>-2.0×10<SP>5</SP>is disclosed. And a method for producing the polyether by ring-opening polymerization of an oxetane derivative by using aluminium benzyl alcoholate bis(2, 6-di-tert-butyl-4-methyl phenolate) as the initiator is also disclosed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyether obtained by ring-opening polymerization of an oxetane derivative, a method for producing the same, and an organoaluminum compound used in the method.

Polyoxetane, which is a polyether obtained by ring-opening polymerization of an oxetane derivative, is used as a polymer liquid crystal (Patent Document 1), a resin component of a thermoplastic elastomer composition (Patent Document 2), and the like. These polyoxetanes are usually produced by cationic polymerization using boron trifluoride-diethyl ether (BF ₃ OEt ₂ ), which is a typical Lewis acid (for example, Patent Document 1).

However, polyoxetane obtained by cationic polymerization using BF ₃ OEt ₂ has a low molecular weight, and development of a higher molecular weight polyoxetane is desired.

Japanese Patent Laid-Open No. 8-20641 Japanese Patent Laid-Open No. 8-27352

  An object of the present invention is to provide a polyoxetane having a higher molecular weight than conventional products, a method for producing the same, and an initiator used in the method.

［式中、Ｒ^１は置換又は非置換のＣ_１−３−アルキル基を表し、Ｘはハロゲン原子又は次式（ａ）：−Ｏ−Ｒ^２（式中、Ｒ^２は有機基を表す。）で示される基を表す。］
で示される繰り返し単位からなり、サイズ排除クロマトグラフィーで測定した数平均分子量Ｍｎが３．５×１０^４〜２．０×１０^５であるポリエーテル。 The present invention includes the following inventions.
(1) The following formula (I):

[In the formula, ^{R 1} represents _{C 1-3} substituted or unsubstituted - alkyl group, X is a halogen atom or the following formula ^{(a): - O-R} 2 ( wherein, ^{R 2} represents an organic group. ) Represents a group represented by ]
A polyether having a number average molecular weight Mn of 3.5 × 10 ^{4 to} 2.0 × 10 ⁵ measured by size exclusion chromatography.

(2) The polyether according to (1) above, wherein the ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn measured by size exclusion chromatography is 1.3 to 4.5.

（式中、Ｒ^１及びＸは前記（１）と同義である。）
で示されるオキセタン誘導体を、次式（III）：

（式中、ｔ−Ｂｕはtert−ブチル基を表し、Ｐｈはフェニル基を表し、Ｍｅはメチル基を表す。）
で示される有機アルミニウム化合物を開始剤として用いて開環重合させることを特徴とする、次式（Ｉ）：

（式中、Ｒ^１及びＸは前記と同義である。）
で示される繰り返し単位からなるポリエーテルの製造方法。 (3) The following formula (II):

(In the formula, R ¹ and X have the same meanings as the above (1).)
An oxetane derivative represented by the following formula (III):

(In the formula, t-Bu represents a tert-butyl group, Ph represents a phenyl group, and Me represents a methyl group.)
Ring opening polymerization using an organoaluminum compound represented by the following formula (I):

(In the formula, R ¹ and X are as defined above.)
The manufacturing method of the polyether which consists of a repeating unit shown by these.

（式中、ｔ−Ｂｕはtert−ブチル基を表し、Ｍｅはメチル基を表す。）
で示される有機アルミニウム化合物の存在下で反応させる前記（３）に記載の製造方法。 (4) Formula (IV):

(In the formula, t-Bu represents a tert-butyl group, and Me represents a methyl group.)
The manufacturing method as described in said (3) made to react in presence of the organoaluminum compound shown by these.

（式中、ｔ−Ｂｕはtert−ブチル基を表し、Ｐｈはフェニル基を表し、Ｍｅはメチル基を表す。）
で示される有機アルミニウム化合物。 (5) The following formula (III):

(In the formula, t-Bu represents a tert-butyl group, Ph represents a phenyl group, and Me represents a methyl group.)
An organoaluminum compound represented by

(6) An initiator comprising the organoaluminum compound represented by the formula (III).

  According to the present invention, it is possible to provide a polyoxetane having a higher molecular weight than conventional products, a method for producing the same, and an initiator used in the method.

  Hereinafter, the present invention will be described in detail.

In the formulas (I) and (II), examples of the C _1-3 -alkyl group represented by R ¹ include a methyl group, an ethyl group, a propyl group, and an isopropyl group. These alkyl groups are halogen atoms (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), C _1-6 -alkoxy groups (for example, methoxy group, ethoxy group, propoxy group), aromatic groups (for example, phenyl group, An aromatic hydrocarbon group such as a tolyl group and a naphthyl group; an aromatic heterocycle such as a furyl group), a carbonyl functional group and the like, which may be substituted.

  Examples of the halogen atom represented by X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the formula (I) and (II), X is the following formula ^{(a): - O-R} 2 ( wherein, ^{R 2} represents an organic group.) Or a group represented by.

Examples of the organic group represented by R ² include a C _1-10 -alkyl group (eg, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl). Group, isopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group), aryl group (for example, phenyl group, 1-naphthyl group, 2-naphthyl group) Aromatic hydrocarbon groups such as groups; aromatic heterocycles such as furyl groups), carbonyl functional groups and the like. The C _1-10 -alkyl group and aryl group are each a halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom), C _1-6 -alkoxy group (eg, methoxy group, ethoxy group, propoxy group), It may be substituted with one or more substituents selected from carbonyl functional groups and the like.

For example, as a substituted C _1-10 -alkyl group, — (CH ₂ ) _n —Hal (wherein n represents an integer of 1 to 10, and Hal represents a halogen atom (for example, a fluorine atom, a chlorine atom, bromine) atom, an iodine _{atom)), -. (CH 2} ) in n -O-Ar-COO-Ar -R 3 ( wherein, n represents an integer of 1 to 10, Ar is a divalent aryl group (e.g. A phenylene group, a biphenylene group, a terphenylene group, a naphthylene group), and R ³ represents a C _1-10 -alkyl group or a C _{1-10 -aliphatic} acyl group which may be substituted with a halogen atom. However, it is not limited to these.

The polyether of the present invention comprises the repeating unit represented by the formula (I), and has a number average molecular weight Mn measured by size exclusion chromatography of 3.5 × 10 ^{4 to} 2.0 × 10 ^5. It is what. The degree of polymerization of the polyether of the present invention is usually 150 to 850, preferably 320 to 850. The number average molecular weight of polyoxetane obtained by cationic polymerization using conventional BF ₃ OEt ₂ by size exclusion chromatography is about 0.35 × 10 ⁴ .

  The ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn measured by size exclusion chromatography of the polyether of the present invention is preferably 1.3 to 4.5, more preferably 1.3 to 3. 5.

  The polyether of the present invention comprises an oxetane derivative represented by the formula (II) and an organoaluminum compound represented by the formula (III) (aluminum benzyl alcoholate bis (2,6-di-tert-butyl-4-methylphenolate; Hereinafter, it may be easily produced by ring-opening polymerization using “BnOAD” as an initiator (polymerization initiator) in some cases, in which case the organoaluminum compound (methylaluminium represented by the above formula (IV)) is prepared. In the presence of bis (2,6-di-tert-butyl-4-methylphenolate; hereinafter referred to as “MAD” in some cases), preferably the reaction is carried out by adding MAD after initiation of polymerization with BnOAD. Is significantly improved.

  Various oxetane derivatives represented by the formula (II) used as a raw material for producing the polyether of the present invention are known, and many are commercially available from Ube Industries, Toagosei Co., Ltd. These can be used as they are. Further, commercially available products can be used after chemically modifying the side chain (pendant) according to a conventional method.

Specific examples of the oxetane derivative represented by the formula (II) include 3,3-bis (chloromethyl) oxetane, 3- (4-bromobutoxymethyl) -3-methyloxetane, and JP-A-8-20641. In the formula (II) described in Patent Document 1), R ¹ is a methyl group, and X is —O (CH ₂ ) _n —O—Ar—COO—Ar—R ³ (wherein n is 1 to 1) Represents an integer of 10, Ar represents a divalent aryl group (for example, a phenylene group, a biphenylene group, a terphenylene group, or a naphthylene group), and R ³ represents a C _1-10 -alkyl which may be substituted with a halogen atom. A group or a C _{1-10 -aliphatic} acyl group).

  The ring-opening polymerization can be performed without a solvent or in a solvent. Solvents that can be used here are not limited as long as they do not substantially prevent ring-opening polymerization, but aromatic hydrocarbon solvents such as benzene and toluene, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2, and the like. , 2-tetrachloroethane, halogen solvents such as chlorobenzene, and the like. In tetrahydrofuran, the ring-opening polymerization hardly proceeds. The reaction temperature of this ring-opening polymerization is usually 0 to 35 ° C., preferably 20 to 30 ° C., and the reaction time is usually 2 to 168 hours, preferably 24 to 168 hours.

  The polyether thus obtained has a hydroxyl group and a benzyloxy group at the end of the main chain, and if necessary, by a method such as debenzylation, alkylation (or arylation), esterification, acylation, etc. Can be chemically modified.

  In the ring-opening polymerization, BnOAD represented by the formula (III) used as an initiator is a novel substance, and can be obtained by reacting equimolar benzyl alcohol with the MAD represented by the formula (IV). it can.

  In addition, when MAD is added and the reaction is carried out in the presence of MAD, preferably after the start of polymerization with BnOAD, the reaction rate is remarkably improved. In this case, the molar ratio of BnOAD to MAD is preferably 1: 1 to 1: 3.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.

1. Reagents Aluminum triphenolate (Al (OPh) ₃ , Aldrich), hexane solution of trimethylaluminum (1.0 mol L ⁻¹ ) (Kanto Chemical), 2,6-di-tert-butyl-4-methylphenol (Kanto Chemical) Were used as they were on the market. Oxetane (Aldrich) was distilled under a nitrogen stream with small pieces of metallic sodium. Benzyl alcohol (Kanto Chemical) was dried over calcium hydride (CaH ₂ ) and distilled under reduced pressure under a nitrogen stream. Boron trifluoride-diethyl ether (BF ₃ OEt ₂ ) (Nacalai) was purified by fractional distillation under reduced pressure under a nitrogen stream. If an anhydrous solvent is required, dichloromethane and chlorobenzene are distilled from powdered calcium hydride immediately before in a nitrogen stream, while toluene and tetrahydrofuran (THF) are distilled immediately before from butyllithium and sodium benzophenone ketyl, respectively. Used. The column chromatography used for product separation was Aluminumoxid 90 (70-230 mesh ASTM) manufactured by Merck. For thin layer chromatography (TLC), aluminum sheets Aluminumoxid 60 F ₂₅₄ neutral manufactured by Merck & Co. were used.

2. Measuring instrument Size exclusion chromatography (SEC) was measured at room temperature using a Shimadzu LC-10A high performance liquid chromatography apparatus equipped with a differential refractometer, using THF at a flow rate of 1.0 mL min ⁻¹ as an eluent. The number average molecular weight (M _{n SEC} ) was determined from a molecular weight comparison curve with standard polystyrene (PSt). Infrared spectra were measured with Shimadzu FTIR-8100 infrared spectrophotometer. ¹ H and ¹³ C NMR spectra were measured at 270.05 and 67.80 MHz for ¹ H and ¹³ C nuclei in CDCl ₃ using a JEOL JNM EX-270 spectrometer, respectively. ¹ H and ¹³ C chemical shifts were determined on the basis of TMS (δ 0.00 ppm) and CDCl ₃ (δ 77.00 ppm), respectively. Homonuclear multiple bond interphase spectra (HMBC) were measured in CDCl ₃ using a JEOL JNM GX-500 spectrometer. Mass spectrometric analysis (HRMS and EIMS) was performed using the JEOL JMS-SX102A mass spectrometer (ionization potential, EIMS for 70 eV) at the Instrument Analysis Center of Kanazawa University.

3. Synthesis of Oxetane Monomer (1) 3- (4-Bromobutoxymethyl) -3-methyloxetane 3-Hydroxymethyl-3-methyloxetane is prepared by equimolar 2-hydroxymethyl-2 in the presence of an alcohol solution of potassium hydroxide. -Reported from methylpropane-1,3-diol and diethyl carbonate ((a) Kanoh, S .; Nishimura, T .; Senda, H .; Motoi, M .; Tanaka, T .; Kano, K. Macromolecules 1999 , 32, 2438-2448. (B) Kanoh, S .; Nishimura, T .; Tsuchida, T .; Senda, H .; Motoi, M .; Takani, M .; Matsuura, N. Macromol Chem Phys 2001, 202 , 2489-2503) (yield, 70%). 3-hydroxymethyl-3-methyloxetane (15.0 g, 147 mmol) in a mixture of 50 wt% aqueous sodium hydroxide (100 mL) and tetrabutylammonium bromide (2.37 g, 7.4 mmol) in hexane (100 mL) And 1,4-dibromobutane (95.4 g, 442 mmol) were added. The mixture was refluxed for 4 hours with vigorous stirring and diluted with water. The ether extract was dried over anhydrous sodium sulfate and then the solvent was removed. The residual oil was distilled from calcium hydride under reduced pressure to give 3- (4-bromobutoxymethyl) -3-methyloxetane (yield, 65%).
Colorless liquid.
Boiling point: 68-71 ℃ (1 mmHg).
FTIR (neat, cm ^-1 ): 1110 (ether stretching), 975 and 830 (cyclic ether stretching), 644 (C-Br stretching).
¹ H NMR (CDCl ₃ , δ, ppm): 4.50 (d, 2H, J = 5.8 Hz, oxetane methylene trans to Me), 4.35 (d, J = 5.8 Hz, 2H, oxetane methylene cis to Me), 3.50 ( t, 2H, OC H ₂ (CH ₂ ) ₃ Br), 3.47 (s, 2H, C ^q C H ₂ O (CH ₂ ) ₄ Br), 3.45 (t, 2H, O (CH ₂ ) ₃ C H ₂ Br), 1.97 (qui, 2H, O (CH ₂ ) ₂ C H ₂ CH ₂ Br), 1.74 (qui, 2H, OCH ₂ C H ₂ (CH ₂ ) ₂ Br), 1.31 (s, 3H, CH ₃ ).
¹³ C NMR (CDCl ₃ , δ, ppm): 80.1 (O C H ₂ in oxetane ring), 76.1 (C ^q C H ₂ O in the pendant group), 70.5 (O C H ₂ (CH ₂ ) ₃ Br) , 39.9 (C ^q ), 33.8 ( C H ₂ Br), 29.7 ( C H ₂ CH ₂ Br), 28.2 ( C H ₂ (CH ₂ ) ₂ Br), 21.4 (CH ₃ ).

(2) (3-Methyloxetane-3-yl) methylbenzoate 3-hydroxymethyl-3-methyloxetane was esterified with benzoyl chloride in dichloromethane in the presence of anhydrous triethylamine (Kanoh, S .; Naka, M .; Yokozuka, T .; Itoh, S .; Nishimura, T .; Honda, M .; Motoi, M .; Matsuura, N. Macromol Chem Phys 2002, 203, 511-521). Extraction by a conventional method gave a crude ester. Distillation under reduced pressure in the presence of calcium hydride gave (3-methyloxetan-3-yl) methylbenzoate (yield, 66%).
Colorless liquid.
Boiling point: 90-92 ° C (1 mmHg).
FTIR (neat, cm ^-1 ): 1720 (C = O stretching), 1280, 1115 (CO stretching), 970 and 835 (cyclic ether stretching).
¹ H NMR (CDCl ₃ , δ, ppm): 8.07 (dd-like, 2H, oH _Ph ), 7.58 (t-like, 1H, pH _Ph ), 7.46 (t, 2H, mH _Ph ), 4.65 (d, J = 6.4 Hz, oxetane methylene trans to Me), 4.46 (d, J = 5.9 Hz, 2H, oxetane methylene cis to Me), 4.40 (s, 2H, C ^q C H ₂ O), 1.43 (s, 3H, CH ₃ ).

4). Synthesis of organoaluminum compounds (1) Methylaluminium Bis (2,6-di-tert-butyl-4-methylphenolate) (MAD)
MAD was prepared according to Aida's method (Adachi, T .; Sugimoto, H .; Aida, T .; Inoue, S. Macromolecules 1993, 26, 1238-1243) and trimethylaluminum and 2,6-di-tert-butyl-4- It was synthesized from methylphenol and recrystallized from hexane under a nitrogen stream to obtain colorless crystals (yield, 60%). MAD was stored as a 0.43 mol L ^-1 toluene solution in a nitrogen atmosphere.

(2) Aluminum Benzyl Alcoholate Bis (2,6-di-tert-butyl-4-methylphenolate) (BnOAD)
The colorless MAD solution (10.0 mL, 4.3 mmol) described above was transferred using a syringe into a test tube fitted with a three-way cock and under a nitrogen stream. A pale yellow solution of BnOAD obtained by dropping equimolar benzyl alcohol (0.44 mL, 4.3 mmol) into the test tube was stored under a nitrogen atmosphere. Similarly, an initiator system of BnOAD / MAD (1: 1) was prepared by adding half the amount of benzyl alcohol to the MAD solution.

5). Coordinated Anionic Polymerization A 25-mL polymerization tube equipped with a three-way cock was repeatedly degassed with nitrogen, and anhydrous toluene (1.0 mL), 3- (4-bromobutoxymethyl) -3-methyloxetane (0.20 g, 0.18 mL, 0.86 mmol) and a toluene solution of BnOAD (0.10 mL, 0.043 mmol, 5 mol%) were sequentially added. The polymerization tube was allowed to stand at 25 ° C. for 24 hours, and a small amount of methanol was added to terminate the polymerization. The reaction mixture was dissolved in dichloromethane (10 mL), and when an insoluble inorganic substance appeared, it was filtered, and the solvent was removed and dried. The crude product was analyzed by ¹ H NMR and SEC to determine the product ratio and average molecular weight (Mn and Mw), respectively. An analytical poly (3- (4-bromobutoxymethyl) -3-methyloxetane) sample was purified by reprecipitation by adding methanol to a dichloromethane solution, and further dried over diphosphorus pentoxide at 80 ° C. under reduced pressure. .

In polymerization using Al (OPh) ₃ instead of BnOAD, a solid initiator (13 mg, 0.043 mmol, 5 mol%) is placed in a degassed nitrogen-substituted polymerization tube and suspended in anhydrous toluene for polymerization. It was.
Poly (3- (4-bromobutoxymethyl) -3-methyloxetane)
FTIR (neat, cm ^-1 ): 1100 (ether stretching), 640 (C-Br stretching).
¹ H NMR (CDCl ₃ , δ, ppm): 3.49-3.38 (m, 4H, OC H ₂ (CH ₂ ) ₂ C H ₂ Br), 3.25 (s, 2H, C ^q C H ₂ O in the pendant group ), 3.20 (s, 4H, OC H ₂ in the main chain), 1.94 (qui, 2H, O (CH ₂ ) ₂ C H ₂ CH ₂ Br), 1.69 (qui, 2H, OCH ₂ C H ₂ (CH _{2) 2 Br), 0.91 (} s, 3H, CH 3).
¹³ C NMR (CDCl ₃ , δ, ppm): 74.3 (OCH ₂ in the main chain), 73.6 (C ^q C H ₂ O in the pendant group), 70.4 (O C H ₂ (CH ₂ ) ₃ Br), 41.4 (C ^q ), 33.9 (CH ₂ Br), 30.0 ( C H ₂ CH ₂ Br), 28.4 ( C H ₂ (CH ₂ ) ₂ Br), 17.7 (CH ₃ ).

6). Cationic Polymerization Cationic polymerization of 3- (4-bromobutoxymethyl) -3-methyloxetane was performed in the same procedure as described above using 5 mol% of BF ₃ OEt ₂ . ^{After 1} H NMR and SEC analysis, methanol was added to a concentrated solution of crude polymer in chloroform and fractionated to remove most of the high molecular weight portion. After removing the solvent from the resulting supernatant, the oligomer part of the residue was separated by column chromatography (ethyl acetate / hexane = 1: 4 v / v), and 3- (4-bromobutoxymethyl) -3- A cyclic tetramer of methyloxetane (yield, 10%) was obtained.
3,7,11,15-tetra (4-bromobutoxymethyl) -3,7,11,15-tetramethyl-1,5,9,13-tetraoxacyclohexadecane (cyclic tetramer)
TLC: Rf = 0.48, ethyl acetate / hexane (1: 4 v / v).
FTIR (neat, cm ^-1 ): 1100 (ether stretching), 650 (C-Br stretching).
¹ H NMR (CDCl ₃ , δ, ppm): 3.47-3.33 (m, 4H, OC H ₂ (CH ₂ ) ₂ C H ₂ Br), 3.24-3.11 (m, 6H, C ^q C H ₂ O in the main chain and the pendant group), 1.95 (qui, 2H, O (CH ₂ ) ₂ C H ₂ CH ₂ Br), 1.68 (qui, 2H, O (CH ₂ ) ₂ C H ₂ CH ₂ Br), 0.92- 0.89 (s with fine splitting, 3H, CH ₃ ).
¹³ C NMR (CDCl ₃ , δ, ppm): 74.6 with fine splitting (C ^q C H ₂ O in the pendant group), 72.1 (O C H ₂ in the main chain), 70.4 (O C H ₂ (CH ₂ ) ₃ Br), 41.4 with fine splitting (C ^q ), 33.9 (CH ₂ Br), 29.9 ( C H ₂ CH ₂ Br), 28.3 ( C H ₂ (CH ₂ ) ₂ Br), 17.8 with fine splitting (CH ₃ ).
FAB HRMS: Found, m / e 949.1674 (calcd for C ₃₆ H ₆₈ O ₈ ⁷⁹ Br ₂ ⁸¹ Br ₂ + H, 949.1687).

7). Results and Discussion (1) Polymerization of 3- (4-bromobutoxymethyl) -3-methyloxetane Oxetane monomers are easily synthesized and their functional groups are relatively stable to acids and bases. -Bromobutoxymethyl) -3-methyloxetane was chosen. Results of polymerizing 3- (4-bromobutoxymethyl) -3-methyloxetane in toluene at 25 ° C. using 5 mol% of initiator with respect to 3- (4-bromobutoxymethyl) -3-methyloxetane Are summarized in Table 1. Normal cationic polymerization using a representative Lewis acid, BF ₃ OEt ₂ , yielded low molecular weight poly (3- (4-bromobutoxymethyl) -3-methyloxetane) (Mn = 3.5'10 ³ ). (run 1). Although MAD is not very effective as a cationic polymerization initiator for oxetane, polymerization of 3- (4-bromobutoxymethyl) -3-methyloxetane occurred even with MAD alone. The obtained polymer had a considerably higher molecular weight (Mn = 2.9′10 ⁴ ) than that obtained with BF ₃ OEt ₂ and a broad molecular weight distribution (Mw / Mn = 5.0) (FIG. 1). The reason for the formation of a substantial amount of high molecular weight may be due to the counter ion effect in cationic chain growth. On the other hand, some MAD may react with hydroxyl components such as water and alcohol slightly mixed in the system to form aluminum trialkoxide species, which may play an important role in the initiation reaction.

In order to prove such a hypothesis, an equimolar amount of benzyl alcohol was added to a toluene solution of MAD to synthesize a well-defined aluminum trialkoxide. The reaction is considered to produce BnOAD with the generation of methane as shown in Reaction Scheme 1. Alkoxy exchange reactions (disproportionation reactions) are unlikely to occur due to steric congestion of 2,6-disubstituted phenolates. Therefore, it is considered that the produced BnOAD exists as a single species in the solution. The inventors succeeded in polymerizing 3- (4-bromobutoxymethyl) -3-methyloxetane using BnOAD, but the polymerization proceeded slowly and the polymer yield was only 60% even in 24 hours. (Table 1, run 5). The obtained polymer had a high molecular weight (Mn = 10.1 × 10 ⁴ ), and the molecular weight distribution was slightly broad (Mw / Mn = 3.0). In contrast, the polymerization stopped when benzyl alcohol was added later during the polymerization. For example, when polymerization initiated by MAD alone was stopped with methanol after 2 hours (Table 1, run 3) and when benzyl alcohol was added after 2 hours and methanol was added after 24 hours (Table 1, run 4) The result is almost unchanged.

(2) Cationically produced poly (3- (4-bromobutoxymethyl) -3-methyloxetane)
The two polymers obtained using BnOAD and BF ₃ OEt ₂ showed clear differences not only in Mn but also in SEC curves and 1H NMR spectra. As shown in FIG. 1, the polymer obtained with BF ₃ OEt ₂ exhibited a multi-modal SEC curve containing a particularly sharp fraction B. ^{In 1} H NMR (FIG. 2), fine splitting was observed in the methyl proton signal of the polymer obtained with BF ₃ OEt ₂ , but in the case of BnOAD, the corresponding signal appeared as a singlet without fine splitting. In order to characterize the oligomer component, poly (3- (4-bromobutoxymethyl) -3-methyloxetane) produced by a cationic mechanism was separated by fractional precipitation and column chromatography with alumina. The SEC curve of the isolated fraction B is shown by a dotted line in FIG. 1, and FIG. 3 compares the difference between the IR spectrum and ¹³ C NMR spectrum of the linear polymer. The IR spectrum of fraction B has no hydroxyl group absorption (arrow portion in FIG. 3), indicating that it has no terminal hydroxyl group. In FAB HRMS, the parent peak appears at 949.1674 mass number / charge and is calculated for one isotopic ion of protonated tetramer, (C ₉ H ₁₇ ⁷⁹ BrO ₂ ) ₂ + (C ₉ H ₁₇ ⁸¹ BrO ₂ ) ₂ + H It was in good agreement with the value. Therefore, the structure of fraction B was determined as a cyclic tetramer produced by back-biting or end-biting cyclization as shown in Reaction Scheme 2.

This is consistent with previous reports that cyclic tetramers mainly form in oxetane cationic oligomerization ((a) Penczek, S .; Slomkowski, S. Cationic Ring-opening Polymerization: Formation of Cyclic Oligomers. In Comprehensive Polymer Science, Allen, G .; Bevington, JC; Eastmond, GC; Ledwith, A .; Russo, S .; Sigwalt, P. Eds .; Pergamon Press: Oxford, 1989; Vol. 3, Chapter 47, pp 725-750. (B) Rose, JB J Chem Soc 1956, 542-546. (C) Arimatsu, Y. J Polym Sci: A-1 1966, 4, 728-729. (D) Dreyfuss, P .; Dreyfuss , MP Polym J 1976, 8, 81-87. (E) Bucquoye, M .; Goethals, EJ Makromol Chem 1978, 179, 1681-1688. (F) Bucquoye, MR; Goethals, EJ Makromol Chem 1981, 182, 3379 -3386). In a similar manner, fractions A and C were identified as a linear polymer and a mixture of linear dimers and trimers, respectively. The ¹³ C signal assignments shown in FIG. 3 were based on both the heteroCOSY spectrum and the HMBC spectrum. Cyclic tetramer C ¹ (pendant methylene carbon directly attached to the ring) and C ^m (ring methylene carbon) signals were found to appear with opposite chemical shift values when compared to the corresponding signals in linear polymers. . It should be noted that there is a fine splitting in the cyclic tetramer C ^q (intra-ring quaternary carbon) signal and especially the C ¹ signal. ^{In 1} H NMR, the methyl proton signal was also split just like a triplet. Perhaps these phenomena are thought to be due to the conformational isomerism of the cyclic tetramer, ie, cone, partial cone, 1,2-alternate, 1,3-alternate conformer.

  As described above, the poly (3- (4-bromobutoxymethyl) -3-methyloxetane) obtained by BnOAD is clear in that it does not form a linear or cyclic oligomer in the cationically produced polymer and Mn. It turned out to be different.

(3) Polymerization of 3- (4-bromobutoxymethyl) -3-methyloxetane promoted by MAD
To accelerate the slow polymerization with BnOAD, bulky Lewis acid MAD was added. It has already been demonstrated that MAD coordinates to oxetane to increase the electron withdrawing property of α-carbon (Takeuchi, D .; Aida, T. Macromolecules 1996, 29, 8096-8100). When MAD (5 mol%) was added immediately after the start of polymerization with 5 mol% BnOAD, the polymerization was significantly accelerated and a high molecular weight polymer was obtained almost quantitatively in 24 hours (Table 1, run 6). . Moreover, there was almost no change in Mn even when MAD was added. On the other hand, when BnOAD and MAD were added simultaneously as a 1: 1 mixture (Table 1, run 7), the results were very similar to polymerization with MAD alone (Table 1, run 2). The acceleration effect by MAD was evaluated from the polymer yield within the polymerization time limited to 2 hours (Table 1, runs 8-10). The polymerization rate increased remarkably with increasing amount of MAD added. FIG. 4 is a time-polymer yield plot in the case of polymerization using 5 mol% of BnOAD, with and without addition of MAD (5 mol%). Both plots show that they are linear over a wide time scale and become pseudo-first order kinetics. From the difference in the slope of the straight line, it was found that the polymerization was about 5.4 times faster when MAD was added compared to the polymerization of BnOAD alone. However, when MAD was added, the polymerization rate decreased when the polymer yield was 85% or more, probably due to a viscous effect. A low conversion rate regardless Mn of the polymer is for example the addition of MAD reach even 1.2-1.4 '10 ^5, Mn did not change almost until the polymer yield of about 80%. This indicates that the polymerization process with BnOAD consists of a very fast growth reaction with a slow initiation reaction and some termination reaction. Furthermore, there was a tendency for relatively low molecular weight polymers to be formed at high conversions. Therefore, the Mn of the polymer obtained at a conversion rate close to 100% was slightly lowered (Mn = 8.1 × 10 ⁴ ) and the molecular weight distribution was also broad (Mw / Mn = 3.0).

  Polymerization with BnOAD accelerated by MAD proceeded in the absence of solvent in addition to dichloromethane and chlorobenzene (Table 1, runs 11-13). With solvent-free polymerization, the polymer was obtained almost quantitatively in 24 hours, but Mw / Mn became broad and Mn decreased. The polymer obtained by polymerization in the absence of solvent was hardly soluble in THF, dichloromethane, or hot chlorobenzene, but the reason for this is still not well understood. There was no reaction in THF, a highly polar and highly coordinating solvent (Table 1, run 14).

(4) Polymerization mechanism Next, the inventors focused on the reaction mechanism of polymerization by BnOAD. The Lewis acidity of BnOAD and MAD can be qualitatively evaluated from the catalytic activity of the reaction giving a bicyclic orthoester from (3-methyloxetane-3-yl) methylbenzoate (Reaction Formula 3). In this isomerization, the intramolecular nucleophilic attack of the ester carbonyl group always takes precedence over the intermolecular nucleophilic attack (ring-opening polymerization) of the oxetanyl group ((a) Kanoh, S .; Naka, M .; Yokozuka, T. Itoh, S .; Nishimura, T .; Honda, M .; Motoi, M .; Matsuura, N. Macromol Chem Phys 2002, 203, 511-521. (B) Corey, EJ; Raju, N. Tetrahedron Lett 1983 , 24, 5571-5574. (C) Kanoh, S .; Naka, M .; Nishimura, T .; Motoi, M. Tetrahedron 2002, 58, 7049-7064). These organoaluminum complexes were found not to have sufficient Lewis acidity to isomerize oxetane esters. This result strongly suggests that neither aluminum complex can cationically polymerize 3- (4-bromobutoxymethyl) -3-methyloxetane.

If the polymerization initiated by BnOAD proceeds anionically, either a benzyloxy group or a 1,2-disubstituted phenyloxy group should be incorporated at the initiation end. However, even in the polymer obtained at the very early stage of polymerization, the molecular weight was so high that the problematic fragment could not be confirmed by ¹ H NMR. Therefore, polymerization was carried out using Al (OPh) ₃ instead of BnOAD (Table 1, run 15). Since this aluminum compound is hardly soluble in toluene, it is not a suitable initiator, and the polymer yield was low even if the reaction time was extended. Fortunately, the molecular weight was low (M _{n SEC} = 1.1 ´ 10 ⁴ ), so NMR analysis was easy. The aromatic region of the ¹ H NMR spectrum is shown in FIG. A small signal of 6.87-6.90 ppm was attributed to the o-, p-protons of the terminal phenyloxy group based on the chemical shift of the model compound 1-phenyloxybutane. The M _{n NMR} of the polymer was estimated to be 1.7 ′ 10 ⁴ from the integrated value. The difference between M _{n SEC} and M _{n NMR} is probably due to integration error or the difference in hydrodynamic volume between poly (3- (4-bromobutoxymethyl) -3-methyloxetane) and standard polystyrene.

By analogy from polymerization initiated with Al (OPh) ₃ , a polymerization mechanism of 3- (4-bromobutoxymethyl) -3-methyloxetane by BnOAD can be proposed. As shown in Reaction Scheme 4, BnOAD coordinates to 3- (4-bromobutoxymethyl) -3-methyloxetane to activate the monomer. And 3- (4-bromobutoxymethyl) -3, which is sterically smaller and therefore more electrophilic, benzyl alcoholate has opened a benzyloxy group by nucleophilic attack on an α-carbon which is electron-deficient in the molecule. -Inserted into the alcoholate of methyl oxetane as the starting end. After other 3- (4-bromobutoxymethyl) -3-methyloxetane is coordinated to the starting species thus formed, the oxetane is subjected to intramolecular nucleophilic attack of oxetane alcoholate or unreacted. 3- (4-Bromobutoxymethyl) -3-methyloxetane coordinated to BnOAD in the molecule undergoes an intermolecular nucleophilic attack and the growth reaction proceeds. In the presence of MAD having a higher Lewis acidity, 3- (4-bromobutoxymethyl) -3-methyloxetane is further activated, so that the contribution of the intermolecular growth process naturally becomes larger.

（式中、OxBrは３−（４−ブロモブトキシメチル）−３−メチルオキセタンを表す。）

(In the formula, OxBr represents 3- (4-bromobutoxymethyl) -3-methyloxetane.)

  BnOAD could polymerize other oxetanes. These monomers always required an electron withdrawing group such as the pendant (side chain) oxymethylene group of 3- (4-bromobutoxymethyl) -3-methyloxetane at the 3-position. The electron withdrawing group may promote the intramolecular nucleophilic attack of benzyl alcoholate in the initiation reaction which is unlikely to occur due to the increase of the electron withdrawing property of the α-carbon. Furthermore, the coordination of MAD also has a synergistic activation effect on the ring-opening polymerizability of these oxetanes. Unsubstituted oxetane did not polymerize with BnOAD. Oxetane, which is commercially available, has a hydroxymethyl group at the 3-position, so that more or less electron withdrawing groups remain after general chemical modification. BnOAD is expected to be a useful initiator in the synthesis of high molecular weight polyethers by such ring-opening polymerization of oxetane.

(5) Conclusion 3- (4-Bromobutoxymethyl) -3-methyloxetane is polymerized under mild conditions using BnOAD, an organoaluminum complex prepared from equimolar benzyl alcohol and MAD, to form a high molecular weight polymer. Succeeded in getting. It was found that the obtained polymer was clearly different from the cationically produced polymer and Mn in that no linear or cyclic oligomer was formed. Polymerization by BnOAD is considered to proceed by an anion ring-opening mechanism based on end group analysis of the polymer obtained using Al (OPh) ₃ . In the presence of bulky Lewis acid MAD, the polymerization was remarkably accelerated, with almost quantitative yield in 24 hours. Unsubstituted oxetane did not polymerize with BnOAD.

  The polyether of the present invention is used in the field of application of conventional polyoxetanes, for example, as a polymer liquid crystal, a resin component of a thermoplastic elastomer composition, and the like. The aluminum compound of the present invention is useful as an initiator for ring-opening polymerization of cyclic ethers.

Shows the SEC curve of the polymer obtained with BF ₃ OEt _2, MAD and BnOAD respectively. 3- (4-bromobutoxymethyl) -3-methyloxetane (OxBr) (bottom), BF ₃ OEt ₂ (top), BnOAD (middle right) and Al (OPh) ₃ (left middle, fragrance ¹ H NMR spectrum of poly (3- (4-bromobutoxymethyl) -3-methyloxetane) obtained by using each of the above (group region). The ¹³ C NMR spectrum and partial IR spectrum of poly (3- (4-bromobutoxymethyl) -3-methyloxetane) (upper figure) and cyclic tetramer (fraction B of FIG. 1) (lower figure) are shown. The polymerization using 5 mol% BnOAD shows the time-polymer yield plot when MAD is not added and when it is added (5 mol%).

Claims (6)

Formula (I):

[In the formula, ^{R 1} represents _{C 1-3} substituted or unsubstituted - alkyl group, X is a halogen atom or the following formula ^{(a): - O-R} 2 ( wherein, ^{R 2} represents an organic group. ) Represents a group represented by ]
A polyether having a number average molecular weight Mn of 3.5 × 10 ^{4 to} 2.0 × 10 ⁵ measured by size exclusion chromatography.   The polyether according to claim 1, wherein the ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn measured by size exclusion chromatography is 1.3 to 4.5. Formula (II):

(Wherein R ¹ and X are as defined in claim 1).
An oxetane derivative represented by the following formula (III):

(In the formula, t-Bu represents a tert-butyl group, Ph represents a phenyl group, and Me represents a methyl group.)
Ring opening polymerization using an organoaluminum compound represented by the following formula (I):

(In the formula, R ¹ and X are as defined above.)
The manufacturing method of the polyether which consists of a repeating unit shown by these. Formula (IV):

(In the formula, t-Bu represents a tert-butyl group, and Me represents a methyl group.)
The production method according to claim 3, wherein the reaction is carried out in the presence of an organoaluminum compound represented by Formula (III):

(In the formula, t-Bu represents a tert-butyl group, Ph represents a phenyl group, and Me represents a methyl group.)
An organoaluminum compound represented by   An initiator comprising an organoaluminum compound represented by the formula (III).

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