JP2012025887A - Method for producing poly(3-substituted thiophene) - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a poly(3-substituted thiophene), which method uses inexpensive raw materials, is easy in a production method, especially in which the reaction temperature control is not needed in a low-temperature region, gives a yield equivalent to that in a conventional method for producing a poly(3-substituted thiophene), and enables the polymer to have excellent stereoregularity and an excellent molecular weight distribution at least equivalent to those of a poly(3-substituted thiophene) produced by the conventional method.SOLUTION: There is provided a method for producing a poly(3-substituted thiophene) comprising polymerizing a monohalogenated 3-substituted thiophene in the presence of a palladium catalyst, an organic alkali metal salt, and a polar aprotic organic solvent.

Description

  The present invention relates to a method for producing poly (3-substituted thiophene).

  Since polythiophene has a polymer structure in which π-conjugated systems are linked, it has electrical conductivity, is excellent in processability, and exhibits relatively high environmental stability and thermal stability. Therefore, polythiophene has recently been attracting attention as a material that can be used in applications such as electrical components such as organic thin film solar cells, organic thin film transistors, photoelectric conversion materials, organic EL materials, diodes, triodes, electro-optic displays, reflective films, and nonlinear optical materials. Collecting.

  Among polythiophenes, poly (3-substituted thiophene) that has attracted attention as a particularly promising polythiophene has a substituent (solubilizing group in a solvent) such as a hexyl group at the 3-position of the thiophene ring. For example, poly (3-alkylthiophene) is known to self-assemble, which is believed to achieve high charge carrier mobility. And it is thought that the one where the molecular weight distribution of poly (3-substituted thiophene) is narrower can highly self-assemble between molecules. In addition, when the electrical component is formed from poly (3-substituted thiophene), the poly (3-substituted thiophene) has a certain molecular weight from the viewpoint of achieving a certain strength and conductivity. Need to be.

  On the other hand, since 3-substituted thiophene as a raw material for synthesizing poly (3-substituted thiophene) has an asymmetric structure, when monomers are polymerized, 2,2 ′ (head-to-head), 5, Three types of linkages can occur: 5 ′ (tail-to-tail) or 2,5 ′ (head-to-tail) linkage. Among these, polymers with many 2,5 ′ (head-to-tail) linkages have high stereoregularity, and can take a polymer structure that is self-assembled and flat and tightly packed. It is suitable for.

  The structure of such poly (3-substituted thiophene) is greatly influenced by the synthesis method. Therefore, various methods for synthesizing poly (3-substituted thiophene) having the above-described constant molecular weight, narrow molecular weight distribution, and high stereoregularity have been proposed.

For example, Patent Document 1 describes a method for synthesizing poly (3-substituted thiophene) represented by the following chemical reaction formula.
That is, reaction is performed by adding zinc chloride to a reaction system in which 2,5-dibromo-3-hexylthiophene and cyclohexylmagnesium chloride are reacted (reactant obtained in the reaction is referred to as reactant 1). Highly reactive “rieke zinc” and further reacting with reactant 1 to give 2-bromo-3-hexyl-5- (bromodincio) thiophene and its isomer 2- (bromogincio) ) -3-hexyl-5-bromothiophene is formed. By adding a Ni catalyst such as Ni (dppe) Cl ₂ (1,2-bis (diphenylphosphinoethane) nickel (II)) to this, poly (3-alkyl) thiophene having high stereoregularity can be obtained. .

  This reaction requires a process for preparing highly active “rieke zinc”, which complicates the manufacturing process. Alternatively, a Rieke zinc solution prepared in advance can be purchased as a reagent from Sigma-Aldrich, etc., but the Rieke zinc solution is very expensive. In any case, the synthesis method of poly (3-substituted thiophene) described in Patent Document 1 is not suitable for industrial production of poly (3-substituted thiophene) from the viewpoint of process and cost.

＊上記化学反応式において、Ｃｙはシクロヘキシル基を表す。

* In the above chemical reaction formula, Cy represents a cyclohexyl group.

Patent Document 2 describes a method in which zinc chloride is changed to manganese chloride in the method described in Patent Document 1, but has the same problem as the method described in Patent Document 1.
Non-Patent Document 1 describes a method for synthesizing poly (3-substituted thiophene) represented by the following chemical reaction formula.

この方法において、工程1で使用するLDAは予めn-ブチルリチウムとジイソプロピルアミンとを−40℃で40分反応させて形成させる必要があり、これに対し、モノマー（２−ブロモ−３−ヘキシルチオフェン）を工程１で加える際には、高い転化率で選択的に５位のプロトンを引き抜き、Ｌｉ化させるために-78℃という低温にする必要がある。

In this method, the LDA used in Step 1 must be formed in advance by reacting n-butyllithium and diisopropylamine at −40 ° C. for 40 minutes, whereas monomer (2-bromo-3-hexylthiophene) is used. ) Is added in step 1, it is necessary to draw a proton at the 5-position selectively at a high conversion rate and to lower the temperature to −78 ° C. to convert it to Li.

Thereafter, the reaction solution was stirred for 40 min at -40 ° C., MgBr ₂ · OEt ₂ was added at -60 ° C. In step 2, the resulting mixture was being stirred 20 minutes, agitation is carried out for 15 minutes at further -40 ° C.. In step 3, Ni (dppp) Cl ₂ (1,3-bis (diphenylphosphinopropane) nickel (II)) is added to the reaction solution at −5 ° C., followed by stirring at room temperature for 12 to 18 hours. There is a need.

  In the method described in Non-Patent Document 1, a multi-step process is necessary, and it is necessary to perform each process in a very low temperature range. When the method is applied to industrial production, There is a problem that the process is very difficult due to the cooling capacity of the management and mass production equipment.

  Patent Documents 3 and 4 describe a method for synthesizing poly (3-substituted thiophene) in which the above problems are improved. In this method, as shown in the following chemical reaction formula, the number of steps is small, the reaction time is about 3 hours, and the reaction temperature is not in the low temperature region but in the reflux temperature condition of THF. That is, the synthesis method is greatly improved from the viewpoint of industrial production.

しかしながら、これらの合成方法で得られたポリマーに関しては、特許文献３および４には分子量及び立体規則性の明確な記載はなく、反応時間の短縮化による分子量の低下及び反応温度の高温化による立体規則性の低下等が懸念される。また、目的物のポリマーの収率は40〜65%程度であり、工業的生産を想定した場合、この収率は決して良いとは言えない。さらに、この反応において反応副生成物として生成する臭化メチルおよびヨウ化メチルは、変異原性の報告がなされている物質である。そのため、当該方法を工業的生産（量産化）に適用した場合には、環境的側面から、前記変異原性物質の処理コストがかさむことも懸念される。

However, with respect to the polymers obtained by these synthesis methods, Patent Documents 3 and 4 do not clearly describe the molecular weight and stereoregularity, and the three-dimensional structure is obtained by reducing the molecular weight by shortening the reaction time and by increasing the reaction temperature. There is concern about a decrease in regularity. In addition, the yield of the target polymer is about 40 to 65%, and this yield is never good when assuming industrial production. Furthermore, methyl bromide and methyl iodide produced as reaction by-products in this reaction are substances that have been reported to be mutagenic. Therefore, when the method is applied to industrial production (mass production), there is a concern that the processing cost of the mutagenic substance is increased from the environmental aspect.

  Non-patent documents 2 and 3 describe a method for synthesizing poly (3-substituted thiophene) represented by the following chemical reaction formula.

＊上記化学反応式において、ＮＩＳはＮ−ヨードスクシンイミドである。

* In the above chemical reaction formula, NIS is N-iodosuccinimide.

  However, in this method, as shown by the above formula, since the synthesis of the monomer used for the polymerization is performed by a multistage reaction, purification in each process (particularly, the reaction at the monomer synthesis stage) is required. Therefore, when this method is applied to the industrial production of poly (3-substituted thiophene), there is a concern that the process becomes complicated.

  Patent Document 5 and Non-Patent Document 4 describe a synthesis method of poly (3-substituted thiophene) represented by the following chemical reaction formula.

＊上記化学反応式において、ＮＢＳはＮ−ブロモスクシンイミドである。

* In the above chemical reaction formula, NBS is N-bromosuccinimide.

  However, this method, like the methods described in Non-Patent Documents 2 and 3 above, involves a multi-step synthesis reaction of the monomer used for polymerization, and therefore requires purification in each process (especially the reaction at the monomer synthesis stage). Therefore, there is a concern that the process becomes complicated when applied to industrial production.

  Non-Patent Document 5 describes a method of obtaining poly (3-hexylthiophene) by polymerizing 2-bromo-3-hexylthiophene in the presence of a palladium catalyst, a specific phosphine compound, cesium carbonate and THF. Has been.

  Patent Document 6 discloses an aromatic monomer having at least two reactive functional groups such as 2,5-dibromo-3-hexylthiophene, a palladium catalyst, an alkali metal alkoxide such as potassium tert-butoxide, and tetrahydrofuran. A method of polymerizing in the presence of an organic solvent such as to obtain poly (3-substituted thiophene) is described. In this method, it is necessary to synthesize dihalogenated 3-substituted thiophene in advance, and in consideration of application to the production of industrial poly (3-substituted thiophene), the process is multistage, and the viewpoint of production cost, etc. It is considered disadvantageous.

Special table 2009-501838 Special table 2009-540055 gazette JP 2000-230040 A JP 2008-81748 A JP 2004-115695 A JP 2007-23252 A

Synthetic metals, 55-57, 1993, 1198-1203 J. Polym Sci Part A: Polym Chem, vol 43, 1454-1462, 2005. J. Polym Sci Part A: Polym Chem vol 46, 4556-4563, 2008. Macromolecules 2004, 37,1169-1171 "Synthesis of polythiophenes based on direct arylation reaction" The 90th Annual Meeting of the Chemical Society of Japan (2010) 2F1-51

  As described above, in many conventional poly (3-substituted thiophene) production methods, substituents such as halogen atoms are introduced at both the 2-position and 5-position of thiophene, and the production process is complicated. .

  The present invention uses an inexpensive raw material, has a simple production process, does not need to control the reaction temperature particularly in a low temperature region, and has a yield equivalent to that of a conventional poly (3-substituted thiophene) production method. It is an object of the present invention to provide a method for producing a poly (3-substituted thiophene) having an excellent stereoregularity and molecular weight distribution equivalent to or better than that of the poly (3-substituted thiophene) produced by the method.

  As a result of intensive studies to solve the above problems, the present inventors have conducted a polymerization reaction in the presence of a specific base, a palladium catalyst, and a specific solvent, thereby reducing the reaction temperature from an inexpensive raw material, particularly in a low temperature region. The present inventors have found that poly (3-substituted thiophene) having characteristics equivalent to or better than those obtained by the conventional method can be easily obtained in a yield equivalent to that obtained by the conventional method without controlling the above. I went to do it.

  That is, the present invention is a method for producing poly (3-substituted thiophene), characterized in that monohalogenated 3-substituted thiophene is polymerized in the presence of a palladium catalyst, an organic alkali metal salt and a polar aprotic organic solvent. is there.

  The palladium catalyst includes a bidentate neutral phosphine ligand, a monodentate neutral phosphine ligand, a neutral π ligand, a monovalent anionic ligand, a divalent anionic ligand, a monodentate A neutral amine ligand, a bidentate neutral amine ligand, a neutral nitrile ligand, and a neutral sulfinyl ligand. Palladium complexes that are coordinated so that the valence is 0 or 2 are preferred.

The organic alkali metal salt is preferably an organic lithium salt.
In the palladium catalyst, the bidentate neutral phosphine ligand is 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,4-bis (diphenylphosphine). Fino) butane or 1,1｀-bis (diphenylphosphino) ferrocene, the monodentate neutral phosphine ligand is tri-n-butylphosphine, tri-t-butylphosphine or triphenylphosphine, The π ligand is benzene, cyclobutadiene or cyclooctadiene, and the monovalent anionic ligand is methyl, phenyl, hexamethylcyclopentadienyl, pentamethylcyclopentadienyl, allyl, cyclopentadienyl. , Alkoxy, fluorine atom, chlorine atom, bromine atom, iodine atom, carboxyra , Acetylacetonate, trifluoromethanesulfonate, 1,3-bis (2,6-di-isopropylphenyl) -4,5-dihydroimidazol-2-lidene, 1,3-bis (2,6 -Di-isopropylphenyl) imidazol-2-lidene or 1,3-bis (2,4,6-trimethylphenyl) imidazole-2-lidene, and the divalent anionic ligand is phthalocyanine, Phthalocyanine or porphyrin, the monodentate neutral amine ligand is ammonia, pyridine or 3-chloropyridine, and the bidentate neutral amine ligand is N, N, N ｀, N｀-tetramethyl. Ethylenediamine, 1,10-phenanthoroline or 2,2｀-bipyridyl, wherein the neutral nitrile ligand is acetonitrile or benzoton Preferably, the neutral sulfinyl ligand is 1,2-bis (phenylsulfinyl) ethane.

  The amount of the palladium catalyst used relative to the monohalogenated 3-substituted thiophene is preferably 0.01 to 50 mol%, and the organic alkali metal salt is used per 1 equivalent of the monohalogenated 3-substituted thiophene. The amount is preferably 0.1 to 10 equivalents.

  The monohalogenated 3-substituted thiophene is preferably a 2-halogenated 3-substituted thiophene represented by the following general formula (I).

式（Ｉ）において、Ｒは直鎖もしくは分岐の炭素数１〜１２のアルキル基、直鎖もしくは分岐の炭素数１〜１２のアルコキシ基、炭素数２〜１２アルケニル基、炭素数２〜１２のアルキニル基または炭素数３〜１２のシクロアルキル基であり、Ｘはハロゲン原子である。

In the formula (I), R represents a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkyl group having 2 to 12 carbon atoms. It is an alkynyl group or a C3-C12 cycloalkyl group, and X is a halogen atom.

  Specific examples of the polar aprotic organic solvent include N, N-dimethylformamide (DMF), N, N-diethylformamide, N, N-dibutylformamide, N, N-diisopropylformamide, N, N, N ′, N′-tetramethylazodicarboxamide, N, N-dimethylthioformamide, bis (diethylthiocarbamoyl) disulfide, bis (dimethylthiocarbamoyl) disulfide, tetramethylthiuram monosulfide, 1-cyclohexyl-2- Pyrrolidone, 1-ethyl-2-pyrrolidone, 1-octyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1,1-carbonyldipiperidine, 1,3-dimethyl-3,4,5,6-tetrahydro- 2 (1H) pyrimidinone, N, N, N ′, N′-tetraisobutylurea and N, N, N ′, N′-tetramethylurea Is, N Among these, N- dimethylformamide (DMF) and N, N, N ', N'- tetramethylurea are preferable.

  According to the present invention, an inexpensive raw material is used, the production process is easy, the reaction temperature is not particularly required to be controlled in a low temperature region, and the yield is equivalent to that of a conventional poly (3-substituted thiophene) production method. Thus, there is provided a method capable of producing poly (3-substituted thiophene) having excellent stereoregularity and molecular weight distribution equivalent to or better than that of poly (3-substituted thiophene) produced by the method.

FIG. 1 shows the ¹ H NMR spectrum of poly (3-hexylthiophene) obtained in Example 1.

Hereafter, the manufacturing method of the poly (3-substituted thiophene) concerning this invention is demonstrated in detail.
[Catalyst component]
As described above, in the method for producing poly (3-substituted thiophene) of the present invention, a monohalogenated 3-substituted thiophene is polymerized in the presence of a palladium catalyst, an organic alkali metal salt, and a polar aprotic organic solvent. . Hereinafter, the organic alkali metal salt and the palladium catalyst which are catalyst components of this reaction will be described.

<Organic alkali metal salt>
The organic alkali metal salt draws out (deprotonates) the active protons of the monohalogenated 3-substituted thiophene as the production raw material in the method for producing poly (3-substituted thiophene) of the present invention, thereby generating an active monomer.

  The organic alkali metal salt used in the present invention is not particularly limited as long as the active proton of the monohalogenated 3-substituted thiophene can be extracted as described above. Examples include methyl lithium, sec-butyl lithium, iso-butyl lithium, n-butyl lithium, cyclopentadienyl lithium, pentyl lithium, phenyl lithium, isopropyl lithium, t-butyl lithium, lithium diphenylphosphinide, lithium (Trimethylsilyl) acetylide, lithium 2-ethylhexoxide, lithium pentamethylcyclopentadienide, lithium 3-fluoropyridine-2-carboxylate, lithium acetate, lithium acetoacetate, lithium acetylacetonate, lithium trifluoroacetate, lithium trifluoro L-methanesulfonate, lithium benzoate, lithium dimethylamide, lithium diethylamide, lithium diisopropylamide, lithium bis (trimethylsilane L) Amide, 1,1-dimethylurea-lithium, 2,2,6,6-tetramethylpiperidine-1-lithium, lithium dicyclohexylamide, bis (trifluoromethane) sulfimidolithium, dilithium phthalocyanine, lithium acetylacetonate Lithium benzene sulfinate, lithium cyclohexane butyrate, lithium (2,4-dichloro-phenoxy) -acetate, lithium ethoxide, lithium isopropoxide, lithium methoxide, lithium phenoxide, lithium phenyl acetylide, lithium salicylate, Lithium t-butoxide, lithium t-amoxide, lithium t-butylcyclopentadienide, lithium tetramethylcyclopentadienide, lithium 2,3,4,5,6-pentachlorophenolate , Lithium trimethylsilanolate, and organic lithium salts such as lithium p- toluenesulfonate and lithium benzene sulfinate.

  Among these, lithium t-butoxide is preferable because it exhibits a reaction activity of preferentially extracting active protons in a competitive reaction in which active halogens and active protons of monohalogenated 3-substituted thiophenes are respectively extracted.

In this invention, the said organic alkali metal salt may be used individually by 1 type, or may be used in combination of 2 or more type.
In addition, from the viewpoint of reaction efficiency, the organic alkali metal salt is preferably used in an amount of 0.1 to 10 equivalents, and 0.5 to 3.0 equivalents, relative to 1 equivalent of the monohalogenated 3-substituted thiophene. More preferably.
The organic alkali metal salts described above can be easily synthesized by known methods, and are widely commercially available.

[Palladium catalyst]
The palladium catalyst is a CC cup composed of a carbon moiety to which a halogen atom is bonded and a deprotonated carbon moiety between active monomers produced by the reaction of the monohalogenated 3-substituted thiophene and an organic alkali metal salt. It is thought to promote the ring. Since CC coupling is performed by such a reaction mechanism, according to the present invention, 2,2 ′ (head-to-head) connection and 5,5 ′ (tail-to-tail) connection are very unlikely to occur. Therefore, poly (3-substituted thiophene) having very high stereoregularity can be obtained.

The palladium catalyst used in the present invention is not particularly limited as long as it is a catalyst having such a catalytic activity ability.
1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,4-bis (diphenylphosphino) butane and 1,1｀-bis (diphenylphosphino) ferrocene A bidentate neutral phosphine ligand,
Monodentate neutral phosphine ligands such as tri-n-butylphosphine, tri-t-butylphosphine and triphenylphosphine,
Neutral π ligands such as benzene, cyclobutadiene and cyclooctadiene,
Methyl, phenyl, hexamethylcyclopentadienyl, pentamethylcyclopentadienyl, allyl, cyclopentadienyl, alkoxy (such as methoxy and phenoxy), fluorine atom, chlorine atom, bromine atom, iodine atom, carboxylate (acetic acid and Propionic acid, etc.), acetylacetonate, trifluoromethanesulfonate, 1,3-bis (2,6-di-isopropylphenyl) -4,5-dihydroimidazol-2-lidene, 1,3-bis ( Monovalent anionic ligands such as 2,6-di-isopropylphenyl) imidazol-2-lidene and 1,3-bis (2,4,6-trimethylphenyl) imidazole-2-lidene,
Divalent anionic ligands such as phthalocyanine, naphthalocyanine and porphyrin,
Monodentate neutral amine ligands such as ammonia, pyridine and 3-chloropyridine,
Bidentate neutral amine ligands such as N, N, N ｀, N｀-tetramethylethylenediamine, 1,10-phenanthrolin and 2,2｀-bipyridyl,
Neutral nitrile ligands such as acetonitrile and benzonitrile,
Alternatively, a palladium complex having a neutral sulfinyl ligand such as 1,2-bis (phenylsulfinyl) ethane as a ligand and coordinated so that the valence of the palladium atom is 0 or 2 is given. be able to. Specific examples of such a palladium catalyst are shown below.

これらの中でも、重合効率の観点から、下記のパラジウム触媒が好ましい。

Among these, the following palladium catalysts are preferable from the viewpoint of polymerization efficiency.

このようなパラジウム触媒は、１種単独で使用しても、２種以上を組み合わせて使用してもよい。

Such a palladium catalyst may be used individually by 1 type, or may be used in combination of 2 or more type.

  Moreover, it is preferable that the said palladium catalyst is used in the ratio of 0.01-50 mol% with respect to the said monohalogenated 3-substituted thiophene (100 mol%) from a viewpoint of polymerization efficiency, More preferably, it is used in a proportion of 10 mol%.

The palladium catalyst described above can be easily synthesized by a known method, and is also widely available on the market.
As described above, the poly (3-substituted thiophene) production method of the present invention does not require the use of an expensive Grignard reagent. In addition, the Grignard reactant must be used in a non-aqueous environment in which the reaction is strict due to its nature, but in the present invention, it is not necessary, so that it is not necessary to spend cost and labor to control the reaction environment. In addition, since a halogenated methyl compound (mutagenic substance) such as methyl bromide derived from a Grignard reactant is not generated, the poly (3-substituted thiophene) of the present invention has less environmental impact than the conventional method. In addition, there is no need to provide facilities for treating mutagenic substances, which is excellent from the viewpoint of cost. Next, a synthesis reaction of poly (3-substituted thiophene) using the catalyst component described above will be described.

[Synthesis of poly (3-substituted thiophene)]
In the present invention, monohalogenated 3-substituted thiophene is polymerized in the presence of a palladium catalyst, an organic alkali metal salt and a polar aprotic organic solvent.

<Monohalogenated 3-substituted thiophene>
The reaction raw material in the method for producing poly (3-substituted thiophene) of the present invention is monohalogenated 3-substituted thiophene. A monohalogenated 3-substituted thiophene particularly suitable as a reaction raw material is a 2-halogenated 3-substituted thiophene represented by the following general formula (I).

上記式において、Ｒは直鎖もしくは分岐の炭素数１〜１２のアルキル基、直鎖もしくは分岐の炭素数１〜１２のアルコキシ基、炭素数２〜１２のアルケニル基、炭素数２〜１２のアルキニル基または炭素数３〜１２のシクロアルキル基であり、Ｘはハロゲン原子である。

In the above formula, R is a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkynyl group having 2 to 12 carbon atoms. Group or a cycloalkyl group having 3 to 12 carbon atoms, and X is a halogen atom.

From the viewpoint of producing a poly (3-substituted thiophene) that is particularly suitable as a material for electrical parts, R is preferably a hexyl group and X is preferably a bromine atom.
Such 2-halogenated 3-substituted thiophenes can be easily synthesized by known methods, and are also commercially available at low cost. As an example of the method, 3-substituted thiophene (which is commercially available and readily available) is present in the presence of a solvent such as cyclopentyl methyl ether, diethyl ether, THF, dibutyl ether, acetic acid, formic acid, propionic acid, etc. Below, the method of obtaining 2-halogenated 3-substituted thiophene by making it react with halogenating agents, such as N-halogenosuccinimide, is mentioned.

  In the present invention, as used in the prior art (Patent Document 6, etc.), the production process is complicated, having substituents (mainly halogen groups) at both the 2-position and 5-position in addition to the 3-position of thiophene. Since monohalogenated 3-substituted thiophenes, particularly preferably 2-halogenated 3-substituted thiophenes, as described above, which are easy to synthesize and inexpensive, as described above, are used instead of some or expensive raw materials. From an economic point of view, it is very advantageous industrially.

<Polar aprotic organic solvent>
In the present invention, the active monomer formed in the reaction system is stabilized by mixing 2-halogenated 3-substituted thiophene and the organic alkali metal salt, and the catalyst component is uniformly dispersed in the reaction system. A polar aprotic organic solvent is used as a polymerization solvent in order to improve the polymerization efficiency by, for example. The solvent is not particularly limited as long as it is an organic solvent that can achieve the above-described object and has polarity but does not have acidic protons. Examples thereof include N, N-dimethylformamide (DMF), N, N-diethylformamide, N, N-dibutylformamide, N, N-diisopropylformamide, N, N, N ′, N′-tetramethylazodi. Carboxamide, N, N-dimethylthioformamide, bis (diethylthiocarbamoyl) disulfide, bis (dimethylthiocarbamoyl) disulfide, tetramethylthiuram monosulfide, 1-cyclohexyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-octyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1,1-carbonyldipiperidine, 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H) pyrimidinone, N, N, Mention may be made of N ′, N′-tetraisobutylurea and N, N, N ′, N′-tetramethylurea. Among these, DMF and N, N, N ′, N′-tetramethylurea are preferable from the viewpoint of polymerization efficiency.

A polar aprotic organic solvent may be used individually by 1 type, or may be used as a mixed solvent combining 2 or more types.
The polar aprotic organic solvent is usually used in an amount of 1 to 20 L, preferably 2 to 10 L, per 1 mol of the raw material monohalogenated 3-substituted thiophene compound.

<Polymerization reaction>
As described above, the polymerization reaction in the present invention is carried out in the presence of a palladium catalyst, an organic alkali metal salt and a polar aprotic organic solvent.

Here, the active proton of the monohalogenated 3-substituted thiophene is first extracted by the organic alkali metal salt to form an active monomer.
Subsequently, the C—C coupling reaction of the carbon moiety from which the active proton is extracted and the carbon moiety to which the halogen atom is bonded of the plurality of active monomer molecules is promoted by the palladium catalyst, and the polymer (ie, poly (3-substituted) Thiophene)) is formed.

  Because of this reaction route, the palladium catalyst and the organic alkali metal salt are charged into the polymerization reaction system by simultaneously charging both the organic alkali metal salt and the active monomer thereafter. A method in which a palladium catalyst is introduced at a stage where a certain amount is formed, and further, a palladium catalyst is introduced in advance (to form a catalytic amount of an oxidative adduct (a kind of active monomer) in advance). Any of the methods of efficiently trapping with a protonated active monomer and allowing the polymerization reaction to proceed smoothly) and then introducing an organic alkali metal salt may be used. Moreover, since the organic alkali metal salt is consumed in the production reaction of the active monomer, the production efficiency of the active monomer may decrease as the reaction proceeds. Therefore, an organic alkali metal salt may be appropriately added as necessary.

  Furthermore, in the present invention, a compound that becomes a ligand that gives a highly active palladium catalyst, such as a phosphine ligand, together with a palladium catalyst is charged into a poly (3-substituted thiophene) polymerization reaction system, and the reaction system Among them, a ligand exchange reaction may be caused between the palladium catalyst and the ligand compound to form a higher activity palladium catalyst.

  As such a compound serving as a ligand that provides a highly active palladium catalyst, the bidentate neutral phosphine ligand compound and monodentate Phosphine ligand compounds. Specific examples thereof include the following compounds.

以上説明した、高活性のパラジウム触媒を与える配位子化合物は、１種単独で使用しても、２種以上を組み合わせて使用してもよい。前記配位子化合物は、公知の方法によって合成が可能であり、また安価に市販もされている。

The ligand compound which gives the highly active palladium catalyst demonstrated above may be used individually by 1 type, or may be used in combination of 2 or more type. The ligand compound can be synthesized by a known method, and is also commercially available at a low cost.

  Moreover, the ligand compound demonstrated above is 5-200 mol% normally with respect to a palladium catalyst (100 mol%) in the manufacturing method of the poly (3-substituted thiophene) of this invention, Preferably it is 50-120 mol%. Used at a rate of

  The reaction carried out in the presence of such a catalyst component and a polar aprotic organic solvent (both formation of the active monomer and its polymerization reaction) can be carried out at normal pressure. Moreover, the reaction temperature of the said reaction is room temperature 25-150 degreeC normally, Preferably it is 40-100 degreeC. That is, the method for producing a poly (3-substituted thiophene) of the present invention does not need to control the temperature in a low temperature region, and can be carried out over the entire process at a reaction temperature that is relatively mild and easy to control. Furthermore, the reaction time of this polymerization reaction (including the reaction for forming an active monomer) is usually 6 to 96 hours, preferably 12 to 48 hours.

  In addition to the catalyst component and the polar aprotic organic solvent described above, a proton trapping agent and / or a halogen trapping agent may be present in the reaction system as necessary.

(Proton trapping agent)
In the present invention, a proton trap (proton sponge) agent may be used for the purpose of accelerating the reaction by capturing protons of the raw material monomer (monohalogenated 3-substituted thiophene).

  Examples of the proton trapping agent include tertiary amine derivatives such as triethylamine, pyridine, 1,8-bis (dimethylamino) naphthalene and 3,4-dihydro-2-pyridol [1,2-a] pyrimidinone. It is done.

A proton trap agent may be used individually by 1 type, or may be used in combination of 2 or more type.
The proton trapping agent described above is usually in a proportion of 10 to 200 mol%, preferably 50 to 100 mol%, based on the monohalogenated 3-substituted thiophene (100 mol%), which is a raw material for synthesizing poly (3-substituted thiophene). Used in.

(Halogen trapping agent)
Furthermore, in the method for producing poly (3-substituted thiophene) of the present invention, a halogen trap agent may be used for the purpose of promoting the reaction by capturing the halogen of the raw material monomer.

Examples of the halogen trapping agent include alkali metal salts such as sodium carbonate, potassium carbonate and cesium carbonate.
A halogen trap agent may be used individually by 1 type, or may be used in combination of 2 or more type.

  The halogen trapping agent described above is usually 10 to 200 mol%, preferably 50 to 100 mol%, based on monohalogenated 3-substituted thiophene (100 mol%), which is a raw material for synthesizing poly (3-substituted thiophene). Used in.

<End capping>
When the polymerization reaction of the polymer is completed, the halogen atom and the deprotonated active site remain at the end of the polymer. If these are left as they are, charge carrier trapping may occur, and the resulting poly (3-substituted thiophene) may have insufficient conductivity.

Therefore, in order to eliminate such inconvenience, end capping is preferably performed in order to remove the halogen atom remaining at the terminal and the active site.
Specifically, at the end of the polymerization reaction, an aliphatic Grignard reagent, dialkyl Grignard reagent or reactive magnesium is added to convert remaining halogen atoms and active sites to Grignard groups. Subsequently, an alkyl end group can be obtained, for example, by adding excess ω-haloalkane. When carrying out a reaction using such a Grignard reagent, it is necessary to realize a non-aqueous environment at least at that stage.

The Grignard reagent is generally represented by R ^p MgX ^q or the like (R ^p is an alkyl group, X ^q is a halogen atom), but R ^p is a hydroxyl or amine group or a protected form thereof. If it is a reactive functional group, such a reactive functional group can be introduce | transduced into the terminal of poly (3-substituted thiophene), and can be endcapped. In addition, end capping can also be performed by using an organolithium reagent instead of the Grignard reagent and then adding ω-haloalkane.

End capping can be performed at any stage, such as before or after recovering the poly (3-substituted thiophene) from the polymerization reaction mixture, or before or after its purification.
In addition, a detailed method of end capping is disclosed in JP-T-2007-501300.

<Purification process>
After completion of the above reaction, water is added to the reaction solution to stop the reaction. Next, the polymer is precipitated by introducing the reaction solution into a poor solvent for the polymer such as excess methanol. The polymer is obtained by filtering this out and collecting the filtrate.

<Poly (3-substituted thiophene)>
By the production method of poly (3-substituted thiophene) of the present invention described above, poly (3-substituted thiophene) having high stereoregularity can be obtained with high yield.

Specifically, the yield is usually 20 to 99%, preferably 40 to 99%, which is comparable to the conventional method for producing poly (3-substituted thiophene).
The regioregularity is usually 90-99%, preferably very high, 95-99. The stereoregularity can be calculated by measuring ¹ HNMR spectrum, and the calculation method (evaluation method) can be roughly classified into two methods.

  One method is to use a signal derived from the proton at the 4-position of the thiophene ring in poly (3-substituted thiophene), and a thiophene ring derived from a stereoregular 2,5 ′ (head-to-tail) linkage. A signal corresponding to the proton at position 4 of (A), a signal corresponding to the proton at position 4 of the thiophene ring derived from the sterically irregular 2,2 ′ (head-to-head) linkage, and 5, The signal (C) corresponding to the proton at position 4 of the thiophene ring derived from the 5 ′ (tail-to-tail) linkage is used. Stereoregularity can be estimated by the integral ratio of the signal (A) and the signal (A + B + C) corresponding to the total proton at the 4-position of the thiophene ring in the polymer.

  Another method is limited to the case where the poly (3-substituted thiophene) has an α-methylene group as a substituent at the 3-position of the thiophene ring, but uses a signal derived from the proton of the α-methylene group. A signal (A ′) corresponding to the α-methylene proton of the 3-position substituent of the thiophene ring derived from the stereoregular 2,5 ′ (head-to-tail) linkage, and the stereoregularity 2,2 ′ (head— Head) Signal (B ′) corresponding to the α-methylene proton of the 3-position substituent of the thiophene ring derived from the linkage, and α-methylene of the 3-position substituent of the thiophene ring derived from the 5,5 ′ (tail-tail) linkage A signal corresponding to a proton (C ′) is used. Stereoregularity can be estimated by the integration ratio between the signal (A ′) and the signal (A ′ + B ′ + C ′) corresponding to the total protons of α-methylene of the 3-position substituent of the thiophene ring in the polymer.

  The number average molecular weight of the poly (3-substituted thiophene) produced by the method for producing poly (3-substituted thiophene) of the present invention is usually 2,000 to 1,000,000, preferably 4,000. ˜500,000, which can exhibit sufficient strength when used as an electronic component or the like. In this specification, the number average molecular weight is a number average molecular weight in terms of standard polystyrene measured by GPC. The same applies to the weight average molecular weight.

  The number average molecular weight (and weight average molecular weight) of the poly (3-substituted thiophene) can be adjusted by changing the type and amount of the palladium catalyst used in the present invention. Specifically, it is as follows. Depending on the type (chemical structure) of the catalyst, the production rate of the polymerization initiating active species generated at the initial stage of polymerization varies. The rate of formation of polymerization-initiating active species depending on the type of catalyst depends on the difference in the three-dimensional structure of the ligand constituting the catalyst, the electronic structure such as electron accepting property and electron donating property, and the three-dimensional structure of the catalyst molecule and the central palladium. It is thought that it is influenced by the difference in electron accepting and electron donating strength in atoms. The rate of formation of the polymerization initiation active species varies depending on the selection of the ligand constituting the catalyst molecule, and is also unambiguously determined because it is influenced by the difference in the activity of the active monomer. Under the precondition that the active monomer deprotonated from the monohalogen monomer of the substituted thiophene is stably supplied, the number of molecules that grow as a polymer is usually high when the rate of generation of the polymerization-initiating active species is high. Therefore, it is considered that it leads to lower molecular weight of each polymer, and conversely, if lower, it leads to higher molecular weight of the polymer.

  When a catalyst having the same chemical structure is used, the production rate of the polymerization initiation active species is the same. Therefore, the molecular weight of the resulting polymer depends on the addition amount of the catalyst. Since the number of seeds increases, it leads to lower molecular weight of the polymer. On the other hand, when the added amount is small, it is considered that higher molecular weight is led.

  The molecular weight distribution of the poly (3-substituted thiophene) is usually 1.0 to 5.0, preferably 1.0 to 2.5, and obtained by a conventional method for producing poly (3-substituted thiophene). It has a narrow molecular weight distribution comparable to that of poly (3-substituted thiophene). Therefore, the poly (3-substituted thiophene) obtained by the production method of the present invention has excellent self-assembling properties similar to those produced by the conventional method, and therefore exhibits excellent conductivity and It is suitable for parts, specifically organic thin film solar cells, organic thin film transistors, photoelectric conversion materials, organic EL materials, diodes, triodes, electro-optical displays, reflective films, nonlinear optical materials and the like.

  When used in such applications, the poly (3-substituted thiophene) is a sensitizer, stabilizer, inhibitor, chain-transfer agent, co-reactive monomer or oligomer, surface active compound, lubricant, wetting agent. One or more other suitable ingredients, such as, dispersants, hydrophobizing agents, adhesives, flow improvers, diluents, colorants, dyes, pigments, or dopants. These components can be added, for example, by dissolving poly (3-substituted thiophene) in a suitable organic solvent, then adding it to the resulting solution, and then evaporating the organic solvent.

  The molecular weight distribution of poly (substituted thiophene) can be adjusted by the supply rate of the active monomer obtained by deprotonation from monohalogenated 3-substituted thiophene, and oxidative addition and reductive elimination in a palladium catalyst. it can.

<Optional process>
As described in the explanation of end capping, in the method for producing a poly (3-substituted thiophene) of the present invention, for example, in addition to the above-described active monomer formation and poly (3-substituted thiophene) formation step, A purification step of poly (3-substituted thiophene) may be performed. Specifically, in addition to the purification described above, the recovered polymer is further added to an organic solvent in which the polymer is dissolved and water for the purpose of further removing the catalyst residue, or for the purpose of removing low molecular weight substances. Liquid separation may be performed using an organic solvent having a low partition coefficient and water, the organic solvent layer may be collected and dehydrated, and then the solid obtained by distilling off the organic solvent may be dried.

  In addition, for the same purpose as described above, the recovered polymer is subjected to Soxhlet extraction with a poor solvent for polymers such as methanol and hexane, the extract is removed, and then extracted with a good solvent that is soluble in the polymer. The extract may be collected and dried.

  Furthermore, for the same purpose as described above, the recovered polymer is further purified by column chromatography using a solvent that can dissolve the polymer and that can be developed by TLC (thin layer chromatography) as the developing solvent. You may implement a process.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
<Synthesis of 2-bromo-3-hexylthiophene>
A 500 mL Schlenk tube was charged with 80 g (475 mmol) of 3-hexylthiophene and 450 mL of THF, and then cooled to 0 ° C. and stirred. Further, 93 g (523 mmol) of N-bromosuccinimide was added to the obtained solution, and then stirred for 3 hours.

  After completion of the reaction, the solvent was distilled off, the reaction residue was transferred to a 1 L flask, hexane (300 mL) and water (500 mL) were added, liquid separation was performed, the hexane layer was separated, and the aqueous layer was extracted again with hexane. (150 mL). The combined hexane layers were washed twice with water (200 mL) and then dried using anhydrous magnesium sulfate, and the solvent was distilled off to obtain a crude product as a pale yellow oil. Further, the crude product was distilled under reduced pressure (75 ° C., −0.4 mmHg) to obtain 2-bromo-3-hexylthiophene as a colorless transparent oil (130 g, yield 90%, GC-MS purity 99%).

<Synthesis of P3HT (poly-3-hexylthiophene): Examples 1 to 4>
In a 20 mL Schlenk tube purged with nitrogen, 0.494 g (2 mmol) of 2-bromo-3-hexylthiophene, 20.4 mg of palladium catalyst Pd (tBu ₃ P) ₂ (2 mol% with respect to the thiophene), and solvents shown in Table 1 below 10 mL was added, heated to 60 ° C., and stirring was started.

  Lithium t-butoxide is added to the above stirring reaction solution under the various addition conditions shown in Table 1 below, followed by the reaction time shown in Table 1, and then 5 mL of water is added to complete the reaction. It was.

  The reaction solution was added to methanol (200 mL) to precipitate a polymer, which was separated by filtration under reduced pressure, washed with water and methanol, dried, and then crude poly (3-hexylthiophene) was obtained as a dry solid. The obtained solid was dissolved in chloroform, filtered, and the filtrate was evaporated, followed by vacuum drying to obtain a polymer solid.

  The molecular weight (weight average molecular weight Mw and number average molecular weight Mn) of the obtained polymer was measured using chloroform as a developing solvent, TSKgel GMHHR-H and TSK-GEL G2500HHR manufactured by Tosoh as columns, and a developing speed of 1 mL / Min, performed by GPC on a polystyrene basis.

Evaluation of stereoregularity of the resulting polymer is carried out in a way that utilizes the signal derived from the ¹ H NMR spectrum to protons of α-methylene group of 3-position substituents in poly (3-substituted thiophene), ¹ H NMR JNM-ECX500 manufactured by JEOL Ltd. was used for the spectrum measurement.

The above results are summarized in Table 1 below. The ¹ H NMR spectrum of the poly (3-hexylthiophene) obtained in Example 1 is shown in FIG.

＜比較例１＞
上記Ｐ３ＨＴの合成の実施例の原料２−ブロモ−３−ヘキシルチオフェンを３−ヘキシルチオフェンに代えて合成を行ったが、反応溶液の着色がみられず、反応後、メタノール（２００ｍＬ）を投入したが、析出物は見られなかった。

<Comparative Example 1>
The raw material 2-bromo-3-hexylthiophene in the above P3HT synthesis example was replaced with 3-hexylthiophene, but the reaction solution was not colored, and methanol (200 mL) was added after the reaction. However, no precipitate was seen.

<Comparative example 2>
The raw material 2-bromo-3-hexylthiophene used in the above P3HT synthesis example was replaced with 2,5-dibromo-3-hexylthiophene, but the reaction solution was not colored, and after the reaction, methanol was used. (200 mL) was added, but no precipitate was observed.

<Comparative Example 3>
Synthesis was performed using toluene (nonpolar aprotic organic solvent) as a solvent for synthesis in the above P3HT synthesis example, but the reaction solution was not colored, and methanol (200 mL) was added after the reaction. However, no precipitate was observed.

<Comparative example 4>
The palladium catalyst Pd (tBu ₃ P) ₂ 20.4 mg (2 mol% with respect to the raw thiophene monomer) of the above P3HT synthesis example was added to the platinum catalyst Pt (Ph ₃ P) ₄ 49.7 mg (with respect to the raw thiophene monomer). The reaction solution was synthesized in place of 2 mol%, but the reaction solution was not colored, and methanol (200 mL) was added after the reaction, but no precipitate was observed.

<Comparative Example 5>
The lithium t-butoxide in the above P3HT synthesis example was replaced with 144 mg of sodium hydroxide (1.8 equivalent, inorganic alkali metal salt relative to the raw thiophene monomer) (0.3 equivalent, 24 mg added every 5 hours). The reaction solution was not colored and methanol (200 mL) was added after the reaction, but no precipitate was observed.

Claims (9)

  A process for producing poly (3-substituted thiophene), comprising polymerizing monohalogenated 3-substituted thiophene in the presence of a palladium catalyst, an organic alkali metal salt and a polar aprotic organic solvent.   The palladium catalyst comprises a bidentate neutral phosphine ligand, a monodentate neutral phosphine ligand, a neutral π ligand, a monovalent anionic ligand, a divalent anionic ligand, a monodentate A neutral amine ligand, a bidentate neutral amine ligand, a neutral nitrile ligand, and a neutral sulfinyl ligand. 2. The method for producing a poly (3-substituted thiophene) according to claim 1, wherein the method is a palladium complex that is coordinated to have a valence of 0 or 2.   The method for producing poly (3-substituted thiophene) according to claim 1 or 2, wherein the organic alkali metal salt is an organic lithium salt. The bidentate neutral phosphine ligand is 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,4-bis (diphenylphosphino) butane or 1,1 ｀ -bis (diphenylphosphino) ferrocene,
The monodentate neutral phosphine ligand is tri-n-butylphosphine, tri-t-butylphosphine or triphenylphosphine;
The neutral π ligand is benzene, cyclobutadiene or cyclooctadiene;
The monovalent anionic ligand is methyl, phenyl, hexamethylcyclopentadienyl, pentamethylcyclopentadienyl, allyl, cyclopentadienyl, alkoxy, fluorine atom, chlorine atom, bromine atom, iodine atom, carboxy Rato, acetylacetonate, trifluoromethanesulfonate, 1,3-bis (2,6-diisopropylphenyl) -4,5-dihydroimidazol-2-lidene, 1,3-bis (2,6 -Di-isopropylphenyl) imidazol-2-lidene or 1,3-bis (2,4,6-trimethylphenyl) imidazole-2-lidene,
The divalent anionic ligand is phthalocyanine, naphthalocyanine or porphyrin,
The monodentate neutral amine ligand is ammonia, pyridine or 3-chloropyridine;
The bidentate neutral amine ligand is N, N, N ｀, N｀-tetramethylethylenediamine, 1,10-phenanthoroline or 2,2｀-bipyridyl;
The neutral nitrile ligand is acetonitrile or benzonitrile;
The method for producing poly (3-substituted thiophene) according to claim 2 or 3, wherein the neutral sulfinyl ligand is 1,2-bis (phenylsulfinyl) ethane.   5. The poly (3-substituted thiophene) according to claim 1, wherein the amount of the palladium catalyst is 0.01 to 50 mol% with respect to the monohalogenated 3-substituted thiophene. Production method.   The amount of the organic alkali metal salt is 0.1 to 10 equivalents with respect to 1 equivalent of the monohalogenated 3-substituted thiophene. Substituted thiophene) production method. The poly (3-substituted thiophene according to any one of claims 1 to 6, wherein the monohalogenated 3-substituted thiophene is a 2-halogenated 3-substituted thiophene represented by the following general formula (I). Method for producing substituted thiophene:

(In the formula (I), R is a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or 2 to 2 carbon atoms. 12 is an alkynyl group or a cycloalkyl group having 3 to 12 carbon atoms, and X is a halogen atom.).   The polar aprotic organic solvent is N, N-dimethylformamide (DMF), N, N-diethylformamide, N, N-dibutylformamide, N, N-diisopropylformamide, N, N, N ′, N′-tetra Methyl azodicarboxamide, N, N-dimethylthioformamide, bis (diethylthiocarbamoyl) disulfide, bis (dimethylthiocarbamoyl) disulfide, tetramethylthiuram monosulfide, 1-cyclohexyl-2-pyrrolidone, 1-ethyl-2 -Pyrrolidone, 1-octyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1,1-carbonyldipiperidine, 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H) pyrimidinone, N Selected from the group consisting of N, N, N ', N'-tetraisobutylurea and N, N, N', N'-tetramethylurea Method for producing a poly (3-substituted thiophene) according to any one of claims 1 to 7, wherein it is one organic solvent.   The polar aprotic organic solvent is N, N-dimethylformamide (DMF) and / or N, N, N ′, N′-tetramethylurea according to claim 1. A process for producing the poly (3-substituted thiophene) described.

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