JPWO2007142188A1 - Polymerization initiator and polymerization method of (meth) acrylic acid derivative - Google Patents

Abstract

There is provided a polymerization initiator capable of polymerizing a (meth) acrylic acid derivative even under a condition in which a monomer and / or a solvent has an active proton. SOLUTION: General formula (1) t-BunR3-nZnM (1) or general formula (2) t-BunR4-nZnMm (2) (wherein n is an integer of 1 to 3 and R is the same or different) An alkyl group having 1 to 12 carbon atoms, an alkenyl group, an aryl group, or an arylalkyl group, wherein M is lithium, magnesium, or MgX (X represents any one of chlorine, bromine, and iodine). A polymerization initiator characterized by comprising a zinc ate complex represented by the formula (1), wherein m is 1 to 2, and polymerization of a (meth) acrylic acid derivative characterized by using the same. Method. [Selection figure] None

Description

  The present invention relates to a polymerization initiator comprising a specific zinc art complex and a method for polymerizing a (meth) acrylic acid derivative using the zinc art complex as a polymerization initiator.

  The organozinc ate complex can be used as an initiator for an anionically polymerizable monomer, as with other organometallic compounds. For example, Furukawa et al. Have proposed that an alkyl earth metal salt of tetraethylzinc is a useful catalyst for the polymerization of methyl vinyl ketone (Patent Document 1), Nakatsuka et al., Dilithium of di-n-butyldiethylzinc. It has been proposed that the salt is useful as a polymerization catalyst for acrylonitriles (Patent Document 2). In addition, Dr. Nishiki et al. Proposed that a barium salt of tetra-n-butylzinc is useful as a polymerization catalyst for butadiene, isoprene and the like (Patent Document 3). For the polymerization of p-trifluoromethylstyrene, it is known that an organic zinc ate complex such as lithium n-butyldiethylzincate as well as n-butyllithium serves as a polymerization initiator (Patent Document 4). It has also been shown that an art complex such as dilithium di-n-butyldiethylzincate can be used as an initiator for stereoregular polymerization of acrylonitrile, as in the case of ordinary organometallic compounds (Patent Document 5). ). In the polymerization of α-fluoroacrylic acid ester, n-butyllithium does not function as a polymerization initiator, whereas organozinc compounds, organoaluminum compounds, and art complexes thereof are excellent as polymerization initiators. -Lithium butyl diethyl zincate is illustrated as a suitable example (patent document 6).

  However, these organozinc complexes must be polymerized under anhydrous conditions in order to exert their catalytic functions.

  On the other hand, tetra-t-butylzinc zincate is useful as a polymerization catalyst for N-isopropylacrylamide, N, N-dimethylacrylamide, hydroxyethyl methacrylate, and the like, and this catalyst is also used in a solution containing water such as hydrous THF. It has been proposed as an epoch-making method capable of advancing living polymerization anionic polymerization (Patent Document 7).

  In the polymerization using an organic metal as an initiator, an organic solvent is generally used. In this case, not only a step of separating and recovering the polymer from the solvent is required, but also an organic solvent waste liquid is generated. On the other hand, development of such an initiator has been desired since these problems can be avoided if the reaction can be carried out with an aqueous solvent. Di-lithium tetra-t-butylzincate that satisfies this requirement can be prepared by reaction of zinc chloride with 4-fold molar amount of t-butyllithium in an ether solvent. However, a t-butyllithium solution is a pyrophoric substance and is expensive, so that it is difficult to handle a large amount industrially. In addition, since a large amount of lithium chloride generated during catalyst synthesis remains, there is a problem that salt may remain in the polymer.

  In addition, it has been known that zinc art complexes other than tetra-t-butylzinc dilithium salt serve as polymerization initiators for monomers having active protons or polymerization initiators in protic solvents. It wasn't.

Furthermore, with regard to zinc art complexes having magnesium as a counter cation, it can be adjusted relatively easily compared to zinc art complexes in which the counter cation is lithium, but examples of use as a polymerization initiator are limited. It was. Although tetraethylzinc zincate has been used as a polymerization initiator for acrylic esters or N-substituted maleimides, the polymerization activity was lower than that of zinc ate complexes having lithium as a counter cation. (Non-Patent Documents 1 and 2). Furthermore, it has not been known to have a polymerization initiating function for a monomer having an active proton, or to have a polymerization initiating function in a protic solvent.
Japanese Examined Patent Publication No. 39-18944 Japanese Examined Patent Publication No. 44-27741 Japanese Patent Publication No. 45-40303 JP-A 63-103189 Japanese Examined Patent Publication No. 7-103189 JP-A-3-103409 JP 2004-292328 A Makromolekulare Chemie, 1986, 187, 731-737. Makromolekulare Chemie, Rapid Communications, 1987, 8, 167-70.

  An object of the present invention is to solve the above-described problems, and relates to a polymerization initiator using an organozinc ate complex and a method for polymerizing a (meth) acrylic acid derivative.

  As a result of diligent efforts to solve this problem, the present inventors have found that an organozinc ate complex having at least one t-butyl group on a zinc atom is suitable as a polymerization initiator for an anion polymerizable monomer. As a result, the present invention has been completed.

That is, the present invention provides the general formula (1)
_{t-Bu n R 3-n} ZnM (1)
Or general formula (2)
_{t-Bu n R 4-n} ZnM m (2)
(In the formula, n is an integer of 1 to 3, R may be the same or different and each represents an alkyl group, alkenyl group, aryl group, or arylalkyl group having 1 to 12 carbon atoms. M is lithium, Magnesium or MgX (X represents any one of chlorine, bromine and iodine) represents a magnesium halide. M represents 1 to 2)
And a (meth) acrylic acid derivative characterized in that the polymerization initiator is a zinc initiator complex represented by the general formula (1) or (2). It relates to the polymerization method.

  By using the organozinc art complex according to the present invention as a polymerization initiator, a polymer can be obtained in a high yield even when a monomer and / or solvent having an active proton is used.

The polymerization initiator of the present invention has the general formula (1)
_{t-Bu n R 3-n} ZnM (1)
Or general formula (2)
_{t-Bu n R 4-n} ZnM m (2)
An organozinc ate complex having at least one t-butyl group represented by the formula:

  Here, n is an integer selected from 1 to 3, R may be the same or different, and is an alkyl group, alkenyl group, aryl group or arylalkyl group having 1 to 12 carbon atoms, specifically methyl. Group, ethyl group, i-propyl group, n-propyl group, n-butyl group, i-butyl group, s-butyl group, n-pentyl group, t-amyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, vinyl group, cyclopentadienyl group, phenyl group, and benzyl group are shown. M represents a magnesium halide represented by lithium, magnesium, or MgX (X represents any one of chlorine, bromine, and iodine). m represents 1 to 2.

More specific examples of the organozinc ate complex used in the present invention include those represented by the general formula (1)
_{t-Bu n R 3-n} ZnM (1)
(T-butyl) lithium dimethyl zincate, (t-butyl) lithium diethyl zincate, (t-butyl) lithium dibutyl zincate, (t-butyl) lithium divinyl zincate, (n-butyl) ) Lithium organic zincate such as lithium dit-butylzincate, lithium bis (t-butyl) phenylzincate, lithium trit-butylzinclate, (t-butyl) dimethylzinc zincate chloride, (t-butyl) ) Magnesium dimethylzinc acid bromide, (t-butyl) magnesium dimethylzincate iodide, di (t-butyl) methylmagnesium zinc chloride, di (t-butyl) methylmagnesium bromide, di (t-butyl) methyl Magnesium zincate iodide, diethyl (t-butyl) zincate magnesium Muchloride, diethyl (t-butyl) zinc acid magnesium bromide, diethyl (t-butyl) magnesium zincate iodide, ethyl di (t-butyl) zinc zinc chloride, ethyl di (t-butyl) zinc magnesium bromide, ethyl di (t -Butyl) magnesium zincate iodide, (t-butyl) dibutylmagnesium chloride, (t-butyl) dibutylmagnesium bromide, (t-butyl) dibutylmagnesium iodide, di (t-butyl) butyl Magnesium zinc chloride, di (t-butyl) butyl magnesium zinc bromide, di (t-butyl) butyl magnesium zinc iodide, (t-butyl) divinyl magnesium zinc chloride, (t-butyl) dibi Magnesium bromide bromide, (t-butyl) divinylmagnesium zinc iodide, diphenyl (t-butyl) magnesium chloride, diphenyl (t-butyl) magnesium bromide, diphenyl (t-butyl) magnesium zinc iodide Dide, Phenyldi (t-butyl) zinc acid magnesium chloride, Phenyldi (t-butyl) zinc magnesium bromide, Phenyldi (t-butyl) zinc magnesium iodide, Tri-t-butylzinc magnesium chloride, Tri-t-butylzinc Examples thereof include organic magnesium zinc halides such as magnesium magnesium bromide and magnesium tri-t-butylzincate iodide.

General formula (2)
_{t-Bu n R 4-n} ZnM m (2)
Specific examples of the organic zinc ate complex represented by the formula include di-lithium tri-t-butylmethylzincate, dilithium tri-t-butylethylzincate, dilithium tri-t-butyl-n-propylzincate, tri-t-butyl- Dilithium i-propylzinc zincate, dilithium tri-t-butyl-n-butylzinc zincate, di-lithium tri-t-butyl-i-butylzinc zincate, dilithium tri-t-butyl-s-butyl zincate, dimethyldi-t- Dilithium butyl zincate, dilithium diethyldi-t-butyl zincate, dilithium di-t-butyldi-n-propyl zincate, dilithium di-t-butyldi-i-propyl zincate, di-n-butyldi-n-butylzinc Dilithium acid, di-n-butyldi-i-butylzinc zincate, di-n-butyldi-s-butyldiethyllithium, methylethyldi-t-butylzinccatenate, methyl-n-butyl-di-t-butylzinc Dilithium acid, methyl -s-Butyl-di-t-butyl dizinc zincate, ethyl-n-butyl-di-t-butyl dilithium zincate, ethyl-s-butyl-di-t-butylzinc zincate, dimethylethyl-t-butyl Dilithium zincate, dimethyl-n-butyl-t-butyldilithium zincate, dimethyl-s-butyl-t-butyldilithium zincate, dimethylethyl-t-butylzinc zincate, diethylmethyl-t-butyldilithium zincate, Dilithium organic zincate such as di-lithium diethyl-n-butyl-t-butylzinc zincate, diethyl-s-butyl-t-butylzinc zincate, tri-t-butylmethylmagnesium zincate, magnesium tri-t-butylethylzincate , Tri-t-butyl-n-propylmagnesium zincate, tri-t-butyl-i-propylmagnesium zincate, tri-t-butyl-n-butylmagnesium zincate, tri-t-butyl-i-butylzinc Acid mug Cium, tri-t-butyl-s-butylmagnesium zincate, dimethyldi-t-butylmagnesium zincate, diethyldi-t-butylmagnesium zincate, di-t-butyldi-n-propylmagnesium zincate, di-t- Butyldi-i-propyl magnesium zincate, di-n-butyldi-n-butylmagnesium zincate, di-n-butyldi-i-butylmagnesium zincate, di-n-butyldi-s-butylmagnesium zincate, methylethyldi- t-Butylzinc zincate, methyl-n-butyl-di-t-butylmagnesium zincate, methyl-s-butyl-di-t-butylmagnesium zincate, ethyl-n-butyl-di-t-butylzincate Magnesium, ethyl-s-butyl-di-t-butylmagnesium zincate, dimethylethyl-t-butylmagnesium zincate, dimethyl-n-butyl-t-butylmagnesium zincate, dimethyl-s-butyl-t-butylzinc acid Organics such as magnesium, dimethylethyl-t-butylmagnesium zincate, diethylmethyl-t-butylmagnesium zincate, diethyl-n-butyl-t-butylmagnesium zincate, diethyl-s-butyl-t-butylmagnesium zincate Mention may be made of magnesium zincate.

  These zinc art complexes can be used as polymerization initiators either individually or as a mixture.

  The zinc art complex having a t-butyl group of the present invention can be synthesized by a reaction between a zinc compound and an organolithium compound or an organomagnesium compound in an inert gas atmosphere.

  For example, it can be synthesized by reacting an organic zinc compound such as dialkyl zinc, diaryl zinc or dialkenyl zinc with an organic magnesium reagent having 1 to 2 equivalents of t-butyllithium or t-butyl group. Moreover, what reacted 1 to 2 equivalent organolithium reagent or organomagnesium reagent with respect to di-t-butyl zinc can also be used.

  Or it can synthesize | combine by making zinc halides, such as zinc chloride, into a starting source, and making 3-4 equivalent of an organic lithium reagent or an organic magnesium reagent react with zinc. At this time, the zinc art complex in the present invention can be synthesized by using an organomagnesium reagent having at least one equivalent of t-butyllithium or t-butyl group.

  For these syntheses, ether solvents such as tetrahydrofuran, diethyl ether, dibutyl ether, cyclopentyl methyl ether, or hydrocarbon solvents such as pentane, hexane, heptane, toluene, and mixtures thereof can be used as reaction solvents. . Among these, an ether solvent is preferably used from the viewpoint of controlling the temperature during the reaction or maintaining uniformity.

  The solution of the synthesized zinc art complex can be used for polymerization as it is.

  Examples of the monomer used for polymerization include (meth) acrylic acid derivatives. (Meth) acrylic acid derivatives include acrylic acid, methacrylic acid and methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, hydroxyethyl methacrylate and other (meth) acrylic acid esters, N-isopropylacrylamide, acrylamide And (meth) acrylic acid amides such as N-isopropylmethacrylamide. These are used alone, but if necessary, a copolymer can be produced by using two or more components or other anionic polymerizable monomers in combination.

  In particular, even for (meth) acryl derivatives having active protons that are deactivated when ordinary organic metals such as hydroxyethyl methacrylate, N-isopropylacrylamide, acrylamide, and N-isopropylmethacrylamide are used, The zinc art complex of the present invention can proceed with polymerization without impairing the polymerization initiation function.

  The solvent used for the polymerization may be a commonly used solvent, for example, a hydrocarbon solvent such as toluene, xylene, hexane, cyclohexane, heptane, an ether solvent system such as THF, diethyl ether, methanol, ethanol, isopropanol, etc. Alcohols and water. In general, water and alcohols easily react with an organometallic compound. Therefore, when they are used as a solvent, the organometallic compound loses the polymerization initiation function. However, the zinc art complex of the present invention can obtain a polymer in a high yield without losing the polymerization initiation function even when a protic solvent system such as water or an alcohol solvent is used as a polymerization solvent.

  The amount of the zinc ate complex used in the polymerization of the (meth) acrylic acid derivative in the present invention is not particularly limited, but it should be used in the range of 0.001 to 10 mol with respect to 100 mol of the (meth) acrylic acid derivative. Is preferred. When the amount is less than this range, sufficient polymerization activity may not be obtained. When the range is exceeded, a large amount of metal residue may be contained in the obtained polymer, and the step of removing it may be a process. It may be necessary.

  Examples of the present invention are shown below, but the present invention is not limited thereto.

Under a regulated nitrogen atmosphere of t-BuEt ₂ ZnLi , 30 mL of THF and 3.72 g (30.1 mmol) of diethyl zinc were added to a 100 mL eggplant flask and cooled to -70 ° C. Under stirring, 9.35 g (29.7 mmol) of a pentane solution of 20.3 wt% t-butyllithium was added dropwise. After dropping, the mixture was stirred at -70 ° C for 30 minutes and then warmed to room temperature. The solvent was concentrated under reduced pressure to obtain 32.2 wt% of t-BuEt ₂ ZnLi in THF.
1H-NMR (THF-d6) d 1.36 (t, 6H), 1.03 (s, 9H), -0.06 (q, 4H)
Moreover, when this solution was decomposed with dilute sulfuric acid and the amount of generated gas was measured, it was confirmed that a gas having a 3-fold molar amount with respect to Zn was generated.
From the above analysis results, it was confirmed that t-BuEt ₂ ZnMgCl was generated.

Polymerization of N-isopropylacrylamide 32.5 wt% of t-BuEt ₂ ZnLi THF prepared in Synthesis Example 1 was added to an aqueous solution of 5.0 g (44.4 mmol) of N-isopropylacrylamide at 20 ° C. in a nitrogen atmosphere. 0.28 g of the solution was added and stirred at room temperature for 1 hour. Then, when it stirred for 30 minutes at 50 degreeC, solid precipitated. 4.0 g of polymer was recovered.

Under a regulated nitrogen atmosphere of t-BuEt ₂ ZnMgCl , 30 mL of THF and 9.65 g (78.1 mmol) of diethylzinc were added to a 100 mL eggplant flask and cooled to −50 ° C. Under stirring conditions, 70 g (78.1 mmol) of 13.0 wt% t-butylmagnesium chloride in THF was added dropwise. After dropping, the mixture was stirred at −50 ° C. for 30 minutes and then heated to room temperature to obtain a 17 wt% THF solution of t-BuEt ₂ ZnMgCl.
1H-NMR (THF-d6) d 1.31 (t, 6H), 1.10 (s, 9H), -0.03 (q, 4H)
Moreover, when the gas amount which consists of a butane and ethane derived from a zinc art complex which produces | generates this solution by decomposition | disassembly with a dilute sulfuric acid was measured, it confirmed that the gas of 3 times mole amount with respect to Zn was generated.
From the above analysis results, it was confirmed that t-BuEt ₂ ZnMgCl was generated.

Polymerization of N-isopropylacrylamide In a nitrogen atmosphere at 20 ° C., an aqueous solution of 5.5 g (48.7 mmol) of N-isopropylacrylamide was added to a THF solution of 17 wt% t-BuEt ₂ ZnMgCl prepared in Synthesis Example 1. 0.8 g was added and stirred at room temperature for 1 hour. Then, when it stirred for 30 minutes at 50 degreeC, solid precipitated. 5.5 g of polymer was recovered.

Under a regulated nitrogen atmosphere of t-Bu ₃ ZnMgCl, 70 mL of THF and 4.73 g (34.7 mmol) of zinc chloride were added to a 300 mL eggplant flask and cooled to 0 ° C. Under stirring conditions, 94 g (104.4 mmol) of a THF solution of 13.0 wt% t-butylmagnesium chloride was added dropwise. After the dropwise addition, the temperature was raised to room temperature, and after filtration, a 7 wt% THF solution of t-Bu ₃ ZnMgCl was obtained.
1H-NMR (THF-d6) d 1.15 (s, 27H)

Polymerization of N-isopropylacrylamide In a nitrogen atmosphere at 20 ° C., an aqueous solution of 5.1 g (40.1 mmol) of N-isopropylacrylamide was added to a THF solution of 7 wt% t-Bu ₃ ZnMgCl prepared in Synthesis Example 1. 0.6 g was added and stirred at room temperature for 1 hour. Then, when it stirred for 30 minutes at 50 degreeC, solid precipitated. 4.9 g of polymer was recovered.

Preparation of t-Bu (n-Bu) ₃ ZnLi ₂ Under a nitrogen atmosphere, 35 mL (35 mmol) of 1M-THF solution of anhydrous zinc chloride was added to a 300 mL eggplant flask and cooled to -70 ° C. Under stirring conditions, 45.3 g (105 mmol) of a hexane solution of 14.9 wt% -n-butyllithium was added dropwise. Furthermore, 10.2 g (34.3 mmol) of a pentane solution of 21.6 wt% -t-butyllithium was added dropwise at −70 ° C. under stirring conditions. After dropping, the mixture was stirred at -70 ° C for 30 minutes and then warmed to room temperature. The solvent was removed under reduced pressure to obtain 39.2 wt% of a THF solution of t-Bu (n-Bu) ₃ ZnLi ₂ .

Polymerization of N-isopropylacrylamide In a nitrogen atmosphere, 0.5 g of a THF solution of t-Bu (n-Bu) ₃ ZnLi ₂ was added to an aqueous solution of 5.1 g (45.0 mmol) of N-isopropylacrylamide at 20 ° C. The mixture was stirred at room temperature for 1 hour. Then, when it stirred for 30 minutes at 50 degreeC, solid precipitated. 4.3 g of polymer was recovered.

Preparation of (t-Bu) ₂ (n-Bu) ₂ ZnLi ₂ 30.1 g (70 mmol) of a hexane solution of 14.9 wt% -n-butyl lithium and a pentane solution of 21.6 wt% -t-butyl lithium A THF solution of 38.9 wt% (t-Bu) ₂ (n-Bu) ₂ ZnLi ₂ was obtained in the same manner as in Example 1 except that 5 g (69.1 mmol) was used.

Polymerization of N-isopropylacrylamide By the same method as in Example 4, 4.8 g of a polymer was obtained from 0.5 g of a 38.9 wt% (t-Bu) ₂ (n-Bu) ₂ ZnLi ₂ THF solution.

Preparation of t-Bu (n-Bu) Et ₂ ZnLi ₂ Under a nitrogen atmosphere, 30 mL of THF and 4.26 g (34.5 mmol) of diethyl zinc were added to a 100 mL eggplant flask and cooled to -70 ° C. Under stirring conditions, 14.9 g (34.8 mmol) of a hexane solution of 14.9 wt% -n-butyllithium was added dropwise. Furthermore, 10.1 g (34.0 mmol) of a pentane solution of 21.6 t% -t-butyllithium was added dropwise at -70 ° C under stirring conditions. After dropping, the mixture was stirred at -70 ° C for 30 minutes and then warmed to room temperature. The solvent was removed under reduced pressure to obtain a 36.8 wt% solution of t-Bu (n-Bu) Et ₂ ZnLi ₂ in THF.

Polymerization of N-isopropylacrylamide In the same manner as in Example 4, 4.1 g of polymer was recovered from 0.5 g of a THF solution of t-Bu (n-Bu) Et ₂ ZnLi ₂ .

Preparation of t-Bu ₂ Et ₂ ZnLi _{2 From} 3.26 g (26.4 mmol) of diethylzinc and 16.2 g (51.3 mmol) of a pentane solution of 20.3% wt-t-butyllithium, the same as in Example 6 By this method, a 22.3 wt% solution of t-Bu ₂ Et ₂ ZnLi ₂ in THF was obtained.

Polymerization of N-isopropylacrylamide In the same manner as in Example 4, 3.9 g of polymer was recovered from 0.5 g of a THF solution of t-Bu ₂ Et ₂ ZnLi ₂ .

Preparation of t-Bu ₂ Et ₂ ZnLi _{2 From} 3.8 g (30.8 mmol) of diethylzinc, 30 ml of toluene and 19.8 g (62.6 mmol) of a pentane solution of 20.3% wt-t-butyllithium After the reaction was carried out in the same manner as in No. 6, the precipitated solid was filtered under a nitrogen atmosphere, and then the solvent was distilled off to obtain a 29.4 wt% toluene solution of t-Bu ₂ Et ₂ ZnLi ₂ .

Polymerization of N-isopropylacrylamide In the same manner as in Example 4, 3.8 g of polymer was recovered from 0.5 g of a toluene solution of t-Bu ₂ Et ₂ ZnLi ₂ .

(Comparative Example 1)
Under a regulated nitrogen atmosphere of n-BuEt ₂ ZnLi , 30 mL of THF and 4.10 g (33.2 mmol) of diethyl zinc were added to a 100 mL eggplant flask, and cooled to -70 ° C. Under stirring conditions, 14.4 g (32.2 mmol) of a 14.9 wt% n-butyllithium hexane solution was added dropwise. After dropping, the mixture was stirred at -70 ° C for 30 minutes and then warmed to room temperature. The solvent was concentrated under reduced pressure to obtain 18.2 wt% of n-BuEt ₂ ZnLi in THF.
1H-NMR (THF-d6) d 1.71 (m, 2H), 1.37 (m, 2H), 1.32 (t, 6H), 0.95 (t, 3H),
-0.05 (t, 2H), -0.16 (q, 4H)

Polymerization of N-isopropylacrylamide In a nitrogen atmosphere at 20 ° C., an aqueous solution of 5.6 g (44.4 mmol) of N-isopropylacrylamide was dissolved in 18.2 wt% of n-BuEt ₂ ZnLi THF prepared in Synthesis Example 2. 0.8 g of the solution was added and stirred at room temperature for 1 hour. Then, although it stirred for 30 minutes at 50 degreeC, solid did not precipitate and a polymer was not collectable.

(Comparative Example 2)
Under a regulated nitrogen atmosphere of PhEt ₂ ZnLi , 30 mL of THF and 4.03 g (32.6 mmol) of diethyl zinc were added to a 100 mL eggplant flask and cooled to −70 ° C. Under stirring conditions, 22.1 g (32.3 mmol) of 12.3 wt% phenyllithium in ether-cyclohexane was added dropwise. After dropping, the mixture was stirred at -70 ° C for 30 minutes and then warmed to room temperature. The solvent was concentrated under reduced pressure to obtain 34.4 wt% PhEt ₂ ZnLi in THF.
1H-NMR (THF-d6) d 7.88 (d, 2H), 7.05 (t, 2H), 6.98 (d, 1H), 1.45 (t, 6H), 0.06 (q,
4H)

Polymerization of N-isopropylacrylamide In a nitrogen atmosphere, an aqueous solution of 5.1 g (45.0 mmol) of N-isopropylacrylamide at 20 ° C. was added to a THF solution of 34.4 wt% PhEt ₂ ZnLi prepared in Synthesis Example 3. 0.6 g was added and stirred at room temperature for 1 hour. Then, although it stirred for 30 minutes at 50 degreeC, solid did not precipitate and a polymer was not collectable.

(Comparative Example 3)
Under a regulated nitrogen atmosphere of s-BuEt ₂ ZnLi , 30 mL of THF and 3.92 g (31.7 mmol) of diethylzinc were added to a 100 mL eggplant flask and cooled to -70 ° C. Under stirring conditions, 19.8 g (32.4 mmol) of a cyclohexane solution of 10.5 wt% s-butyllithium was added dropwise. After dropping, the mixture was stirred at -70 ° C for 30 minutes and then warmed to room temperature. The solvent was concentrated under reduced pressure to obtain a 32.8 wt% s-BuEt ₂ ZnLi solution in THF.
1H-NMR (THF-d6) d 1.67 (m, 2H), 1.34 (t, 9H), 1.03 (t, 3H), 0.27 (m, 1H), -0.15 (q, 4H)

Polymerization of N-isopropylacrylamide 32.5 wt% of s-BuEt ₂ ZnLi THF prepared in Synthesis Example 4 was added to an aqueous solution of 5.3 g (46.8 mmol) of N-isopropylacrylamide at 20 ° C. in a nitrogen atmosphere. 0.7 g of the solution was added and stirred at room temperature for 1 hour. Then, although it stirred for 30 minutes at 50 degreeC, solid did not precipitate and a polymer was not collectable.

(Comparative Example 4)
Under a regulated nitrogen atmosphere of n-BuEt ₂ ZnMgCl , 10 mL of THF and 2.54 g (20.6 mmol) of diethyl zinc were added to a 100 mL eggplant flask and cooled to −50 ° C. Under stirring conditions, 9.85 g (20.6 mmol) of 24.4 wt% n-butymagnesium chloride in THF was added dropwise. After dropping, the mixture was stirred at −50 ° C. for 30 minutes and then warmed to room temperature to obtain a 23.4 wt% n-BuEt ₂ MgCl THF solution.
1H-NMR (THF-d6) d 1.66 (m, 2H), 1.41 (m, 2H), 1.29 (t, 6H), 1.01 (t, 3H), 0.08
(t, 2H), -0.05 (q, 4H)

Polymerization of N-isopropylacrylamide 25.3 wt% of n-BuEt ₂ ZnLi THF prepared in Synthesis Example 2 was added to an aqueous solution of 5.3 g (46.8 mmol) of N-isopropylacrylamide at 20 ° C. in a nitrogen atmosphere. 0.8 g of the solution was added and stirred at room temperature for 1 hour. Then, although it stirred for 30 minutes at 50 degreeC, solid did not precipitate and a polymer was not collectable.

(Comparative Example 5)
Preparation of n-Bu ₂ Et ₂ ZnLi ₂ Under a nitrogen atmosphere, 30 mL of THF and 2.75 g (22.2 mmol) of diethyl zinc were added to a 100 mL eggplant flask and cooled to -70 ° C. Under stirring, 19.0 g (45.5 mmol) of a hexane solution of 15.3 wt% -n-butyllithium was added dropwise. After dropping, the mixture was stirred at -70 ° C for 30 minutes and then warmed to room temperature. The solvent was removed under reduced pressure to obtain 38.1 wt% of a THF solution of n-Bu ₂ Et ₂ ZnLi ₂ .

Polymerization Example of N-Isopropylacrylamide In a nitrogen atmosphere, 0.5 g of n-Bu ₂ Et ₂ ZnLi ₂ in THF was added to an aqueous solution of 5.0 g (44.1 mmol) of N-isopropylacrylamide at 20 ° C. For 2 hours. Then, it stirred at 50 degreeC for 30 minutes. Solid did not precipitate and no polymer was obtained.

  From this result, it was confirmed that the zinc ate complex having no t-butyl group does not function as a polymerization initiator when a protic solvent such as water is used.

  The present invention is useful for the polymerization of (meth) acrylic acid derivatives.

Claims (5)

General formula (1)
_{t-Bu n R 3-n} ZnM (1)
Or general formula (2)
_{t-Bu n R 4-n} ZnM m (2)
(In the formula, n is an integer of 1 to 3, R may be the same or different and each represents an alkyl group, alkenyl group, aryl group, or arylalkyl group having 1 to 12 carbon atoms. M is lithium, Magnesium or MgX (X represents any one of chlorine, bromine and iodine) represents a magnesium halide. M represents 1 to 2)
A polymerization initiator comprising a zinc ate complex represented by the formula: A method for polymerizing a (meth) acrylic acid derivative, wherein the zinc art complex represented by the general formula (1) or (2) according to claim 1 is used as a polymerization initiator. The method for polymerizing a (meth) acrylic acid derivative according to claim 2, wherein the solvent used for the polymerization is a protic solvent. 4. The method for polymerizing a (meth) acrylic acid derivative according to claim 3, wherein the protic solvent is water. The method for polymerizing a (meth) acrylic acid derivative according to any one of claims 2 to 4, wherein the (meth) acrylic acid derivative is a compound having an active proton.