EP2178943A1

EP2178943A1 - Method for the production of thiophene oligomers

Info

Publication number: EP2178943A1
Application number: EP08785276A
Authority: EP
Inventors: Björn HENNINGER; Frank Rauscher; Leslaw Mleczko
Original assignee: Bayer Technology Services GmbH
Current assignee: Bayer Intellectual Property GmbH
Priority date: 2007-08-14
Filing date: 2008-08-01
Publication date: 2010-04-28
Also published as: TW200916499A; CN101809059A; CA2696173A1; TWI421272B; US8394916B2; KR20100049067A; CN101809059B; JP2010535823A; US20100190945A1; DE102007038449A1; WO2009021639A1

Abstract

The present invention relates to a method for the oligothiophene synthesis at increased temperatures and low catalyst concentrations.

Description

Process for the preparation of thiophene oligomers

The present invention relates to a process for the preparation of oligothiophenes.

The field of molecular electronics has developed rapidly in the last 15 years with the discovery of organic conducting and semiconducting compounds. During this time, a variety of compounds have been found that have semiconducting or electro-optical properties. It is generally understood that molecular electronics will not displace conventional silicon-based semiconductor devices. Instead, it is expected that molecular electronic devices will open up new applications that require the ability to coat large areas, structural flexibility, low temperature processability, and low cost. Semiconducting organic compounds are currently being developed for applications such as organic field effect transistors (OFETs), organic light emitting diodes (OLEDs), sensors and photovoltaic elements. Simple structuring and integration of OFETs into integrated organic semiconductor circuits makes possible low-cost solutions for smart cards or price tags, which hitherto can not be realized with the aid of silicon technology due to the price and lack of flexibility of the silicon components. Also, OFETs could be used as switching elements in large area flexible matrix displays.

All compounds have continuous conjugated units and are subdivided into conjugated polymers and conjugated oligomers depending on their molecular weight and structure. A distinction is usually oligomers of polymers in that oligomers usually have a narrow molecular weight distribution and a molecular weight to about 10,000 g / mol (Da), whereas polymers usually have a correspondingly higher molecular weight and a broader molecular weight distribution. However, it makes more sense to differentiate on the basis of the number of repeating units, since a monomer unit can certainly reach a molecular weight of 300 to 500 g / mol, as for example in (3,3 "-dihexyl) -quarterthiophene. In the case of a distinction according to the number of repeating units, one speaks in the range from 2 to about 20 of oligomers. However, there is a smooth transition between oligomers and polymers. Often, the distinction between oligomers and polymers also expresses the difference in the processing of these compounds. Oligomers are often vaporizable and can be applied to substrates by vapor deposition. Independently of their molecular structure, polymers are often referred to as compounds which are no longer volatilizable and are therefore generally applied by other processes. An important prerequisite for the production of high-quality organic semiconductor circuits are compounds of extremely high purity. In semiconductors, order phenomena play a major role. Obstruction in uniform alignment of the bonds and forms of grain boundaries leads to a dramatic decrease in semiconductor properties, so that organic semiconductor circuits constructed using non-extremely high purity compounds are usually unusable. Remaining impurities, for example, inject charges into the semiconducting compound ("doping") and thus reduce the on / off ratio or serve as charge traps and thus drastically reduce mobility. Furthermore, impurities can initiate the reaction of the semiconducting compounds with oxygen, and oxidizing impurities can oxidize the semiconducting compounds, thus shortening possible storage, processing and operating times.

The most important semiconducting poly- or oligomers include the oligothiophenes whose monomer unit is e.g. 3-hexylthiophene. When linking one or more thiophene units to a polymer or oligomer, a distinction must in principle be made between two processes - the simple coupling reaction and the multiple coupling reaction in the sense of a polymerization mechanism.

In the simple coupling reaction two thiophene derivatives with the same or different structure are usually coupled together in one step, so that a molecule is formed, which then consists of one unit of each of the two components. After separation, purification, and re-functionalization, this new molecule can in turn serve as a monomer, giving access to longer-chain molecules. This process usually leads to exactly one oligomer, the target molecule and thus to a product without molecular weight distribution, and few by-products. They also offer the possibility of building very defined block copolymers by using different building blocks. The disadvantage here is that molecules which consist of more than 2 monomer units are already very expensive to produce due to the Aufremigungsschritte and the economic cost can be justified only in processes with very high quality requirements of the product.

A process for the synthesis of oligothiophenes is described inter alia in EP 1 026 138. In the actual polymerization, a regioselectively prepared Grignard compound is used as the monomer (X = halogen, R = substituent):

For the polymerization, the polymerization in a catalytic cycle is started by the Kumada method (cross-coupling metathesis reaction) using a nickel catalyst (preferably Ni (dppp) Cl ₂ ).

The polymers are generally obtained via Soxhlet purifications of the necessary purity.

In EP 1 026 138, the reaction is carried out so that first (as quantitatively as possible) the Grignard reagent is prepared and then the polymerization of the thiophene is carried out by addition of the nickel catalyst under C-C linkage. Similar methods can be found i.a. in US 4,521,589 and in Loewe et al, Advanced Materials 1999, 11, No.3, pp. 250-253 and Iraqi et al., Journal of Materials Chemistry, 1998, 8 (1), pp. 25-29 ,

The reaction mechanism of the so-called "Kumada" reaction is, according to common opinion, the so-called "quasi-living" Grignard methathesis reaction. See two documents of Richard D. McCullough et al., M.C. Iovy et al. Macromolecules 2005, 38, 8649-8656, and E.E. Sheina, Macromolecules 2004, 37, 3526-3528.

Accordingly, the polymerization proceeds in particular of 3-substituted, 2-5-dibromothiophenes presumably by the following mechanism (Scheme 1, from Macromolecules 2005, 38, 8649-8656): MgCl [1]: [1T = 85: 15 to 75: 25 cydes

reductive elimination

Thus, according to this mechanism, the chain length largely depends on the number of active catalyst centers and the amount of monomer, the molecular weight being broadened by statistical distribution of the monomer onto the growing chains. The growing chain is predominantly coordinated to a nickel center.

The relationship between molecular weight and catalyst concentration is also clear from Fig. 3 of the same document:

Conversion (%)

Fig. 3 from Macromolecules 2005, 38, 8649-8656

In this scheme, the molecular weight distribution and the average molecular mass of oligo or polythiophenes as a function of the catalyst concentration (Ni (H)) are shown in each case. It can be clearly seen that as the concentration of catalyst increases, the molecular weight decreases, which is in line with the postulated mechanism.

For the targeted synthesis of oligomers, therefore, a high amount of catalyst is absolutely necessary according to the mechanism described. However, a high amount of catalyst is undesirable, especially in a large-scale application.

Starting from the prior art, the object of the present invention was therefore to provide a method which at least partially overcomes the disadvantages mentioned and enables the production, in particular the large-scale production of oligothiophenes with the lowest possible catalyst concentration.

This object is achieved by a method according to claim 1 of the present invention. Accordingly, a method for the polymerization of at least one thiophene derivative having at least two leaving groups to oligomers is proposed, wherein the polymerization by means of a thiophene-organometallic compound and at least one catalyst, characterized in that the method at a catalyst concentration (based on the molar amount of the thiophene derivative used) of> 0.01 - <0.95 mol% and a temperature of> 105 ° C - <155 ° C is performed.

It has surprisingly been found that oligomers of defined chain length and molecular weight distribution are obtained under these conditions, while polymers are formed with larger amounts of catalyst.

The term "oligomers" means in particular thiophene derivatives having a chain length of chain lengths with n> 2 to <20 monomer units, preferably from> 3 to <12, more preferably from> 4 to <10 and most preferably from> 5 to <8. Accordingly, the molecular weight of the oligothiophenes obtainable by the process is from the molecular weight of the monomeric thiophene derivative from> 800 to <6000, preferably from> 900 to <5000, more preferably from> 1000 to <3000, most preferably from> 1000 to <2500 ,

The exact circumstances of this surprising finding - especially on a mechanistic level - are not well known or investigated; however, it seems that the mechanism previously adopted in the art is not applicable in this narrow sub-sector.

Preferably, the process at a catalyst concentration (based on the molar amount of the thiophene derivative used) of> 0.05 - <0.85 mol%, preferably> 0.15 - <0.75 mol%, further preferably of> 0 , 25 - <0.55 mol%, and most preferably> 0.35 - <0.45 mol%.

Preferably, the process proceeds at a temperature of> 110 ° C - <150 ° C, more preferably> 115 ° C - <145 ° C, and most preferably> 120 ° C - <140 ° C.

According to a preferred embodiment of the invention, the reaction takes place at elevated pressures, preferably at> 1-30 bar, in particular at> 2-15 bar and particularly preferably in the range of> 4-10 bar.

For the purposes of the present invention, the term "thiophene derivative" is understood to mean both mono-, di- or polysubstituted and unsubstituted thiophene.Preferred are thiophene derivatives which are alkyl-substituted, particularly preferably 3-alkyl-substituted thiophene derivatives.

For the purposes of the present invention, the term "leaving group" is understood in particular to mean any group which is protected by means of a metal or an organometallic compound Forming a thiophene-organometallic compound is able to react. Particularly preferred leaving groups are halogens, sulfates, sulfonates and diazo groups.

According to a preferred embodiment of the invention, the at least one thiophene derivative contains at least two different leaving groups. This may be useful for achieving better regioselectivity of the polymer in many applications of the present invention.

According to an alternative preferred embodiment of the invention, the leaving groups of the at least one thiophene derivative are identical.

For the purposes of the present invention, the term "thiophene-organometallic compound" is understood in particular to mean a compound in which at least one metal-carbon bond to one of the carbon atoms on the thiophene heterocycle is present.

The term "organometallic compound" is understood in particular to mean an alkylmetalorganic compound.

Preferred metals within the at least one thiophene-organometallic compound are tin, magnesium, zinc and boron. It should be understood that within the present invention, boron is also considered to be a metal. In the event that the process according to the invention proceeds with the participation of boron, the leaving group is preferably selected from the group comprising MgBr, MgI, MgCl, Li or mixtures thereof.

The organometallic compounds which are used in the process according to the invention are preferably organometallic Sn compounds, for example tributyltin chloride, or Zn compounds, for example activated zinc (Zn *) or borane compounds, for example B ( OMe) ₃ or B (OH) ₃ , or Mg compounds, particularly preferably organometallic Mg compounds, particularly preferably Grignard compounds of the formula R-Mg-X,

where R is alkyl, very particularly preferably C2-alkyl,

and X is halogen, more preferably Cl, Br or I, and most preferably Br.

The term "catalyst" is understood in particular to mean a catalytically active metal compound. According to a preferred embodiment of the invention, the at least one catalyst contains nickel and / or palladium. This has been found to be favorable in many application examples of the present invention.

The at least one catalyst particularly preferably contains at least one compound selected from the group of nickel and palladium catalysts with ligands selected from the group consisting of tri-tert-butylphosphine, triadamantylphosphine, 1,3-bis (2,4,6-trimethylphenyl) imidazolidinium chloride, 1,3-bis (2,6-diisopropylphenyl) imidazolidinium chloride or 1,3-diadamantylimidazolidinium chloride or mixtures thereof; To-

(triphenylphosphino) palladium dichloride (Pd (PPh ₃ ) Cl ₂ ), palladium (II) acetate (Pd (OAc) ₂ ), tetrakis (triphenylphosphine) palladium (Pd (PPh ₃ ) ₄ ), tetrakis (triphenylphosphine) nickel (Ni (PPh ₃₎ _4), nickel-ü acetylacetonate Ni (acac) _2, dichloro (2,2'-bipyridine) nickel, Dibromobis- (triphenylphosphine) nickel (Ni (PPh ₃₎ ₂ Br _2), bis (diphenylphosphino) propane Nickel dichloride (Ni (dppp) Cl ₂ ) or bis (diphenylphosphino) ethane nickel dichloride Ni (dppe) Cl ₂ or mixtures thereof

General Group Definition: Within the specification and claims, general groups such as: alkyl, alkoxy, aryl, etc. are claimed and described. Unless otherwise described, the following groups are preferably used within the groups generally described in the context of the present invention:

alkyl: linear and branched C 1 -C 8 -alkyls,

long-chain alkyls: linear and branched C5-C20 alkyls

alkenyl: C2-C8 alkenyl,

cycloalkyl: C3-C8-cycloalkyl,

alkoxy: Cl-C6-alkoxy,

long-chain alkoxy: linear and branched C5-C20 alkoxy

Alkylene: selected from the group comprising:

methylene; 1, 1 -ethylene; 1,2-ethylene; 1,1-propylidene; 1,2-propylene; 1,3-propylene; 2,2-propylidenes; butan-2-ol-l, 4-diyl; propan-2-ol-l, 3-diyl; 1, 4-butylenes; cyclohexane-l, l-diyl; cyclohexane-l, 2-diyl; cyclohexane-1,3-diyl; cyclohexane-l, 4-diyl; cyclopentane-l, l-diyl; cyclopentane-l, 2-diyl; and cyclopentane-1,3-diyl, aryl: selected from aromatics having a molecular weight below 300Da.

arylenes: selected from the group comprising: 1,2-phenylenes; 1,3-phenylenes; 1, 4-phenylene; 1,2-naphthalenylenes; 1,3-naphtalenylene; 1,4-naphthalenylenes; 2,3-naphtalenylene; 1-hydroxy-2,3-phenylene; 1-hydroxy-2,4-phenylene; 1-hydroxy-2,5-phenylene; and 1-hydroxy-2,6-phenylene,

heteroaryl: selected from the group comprising: pyridinyl; pyrimidinyl; pyrazinyl; triazolyl; pyridazinyl; 1,3,5-triazinyl; quinolinyl; isoquinolinyl; quinoxalinyl; imidazolyl; pyrazolyl; benzimidazolyl; thiazolyl; oxazolidinyl; pyrrolyl; thiophenyl; carbazolyl; indolyl; and isoindolyl, wherein the heteroaryl may be linked to the compound via any atom in the ring of the selected heteroaryl.

heteroarylenes: selected from the group comprising: pyridinediyl; quinolindiyl; pyrazodiyl; pyrazoldiyl; triazolediyl; pyrazinediyl, thiophenediyl; and imidazolediyl, wherein the heteroarylene functions as a bridge in the compound via any atom in the ring of the selected heteroaryl, especially preferred are: pyridine-2,3-diyl; pyridin-2,4-diyl; pyridin-2,5-diyl; pyridine-2,6-diyl; pyridine-3,4-diyl; pyridine-3,5-diyl; quinolin-2,3-diyl; quinolin-2,4-diyl; quinoline-2, 8-diyl; isoquinoline-1, 3-diyl; isoquinoline-l, 4-diyl; pyrazole-1, 3-diyl; pyrazol-3,5-diyl; triazole-3,5-diyl; triazole-1, 3-diyl; pyrazin-2,5-diyl; and imidazole-2,4-diyl, thiophene-2,5-diyl, thiophene-3,5-diyl; a -CC-C6 heterocycloalkyl selected from the group comprising: piperidinyl; piperidines; 1,4-piperazines, tetrahydrothiophenes; tetrahydrofuran; 1, 4,7-triazacyclononane; 1,4,8,11-tetraazacyclotetradecane; 1, 4,7, 10, 13-pentaazacyclopentadecane; 1,4-diaza-7-thia-cyclononane; l, 4-diaza-7-oxa-cyclononane; 1,4,7,10-tetraazacyclododecanes; 1,4-dioxane; 1, 4,7-trithia-cyclononane; pyrrolidines; and tetrahydropyran, wherein the heteroaryl may be linked to the C 1 -C 6 alkyl via any atom in the ring of the selected heteroaryl.

heterocycloalkylenes: selected from the group comprising: piperidin-1,2-ylenes; piperidin-2,6-ylene; piperidin-4,4-ylidene; l, 4-piperazin-l, 4-ylene; l, 4-piperazin-2,3-ylene; 1, 4-piperazine-2,5-ylene; 1, 4-piperazine-2,6-ylene; 1, 4-piperazine-1,2-ylene; 1,4-piperazine-1,3-ethylene; 1, 4-piperazine-1, 4-ylene; tetrahydrothiophen-2,5-ylene; tetrahydrothiophen-3,4-ylene; tetrahydrothiophen-2,3-ylene; tetrahydrofuran-2,5-ylene; tetrahydrofuran-3,4-ylene; tetrahydrofuran-2,3-ylene; pyrrolidine-2,5-ylene; pyrrolidin-3,4-ylene; pyrrolidin-2,3-ylene; Pyrrolidin-1,2-ylene; pyrrolidin-l, 3-ylene; pyrrolidin-2,2-ylidene; l, 4,7-triazacyclonon-l, 4-ylene; 1,4,7-triazacyclonon-2,3-ylene; 1,4,7-triazacyclonon-2,9-ylene; l, 4,7-triazacyclonon-3,8-ylene; 1, 4,7-triazacyclonon-2,2-ylidenes; 1,4,8,1-tetraazacyclotetradec-1,4-ylene; 1,4,8,11-tetraazacyclotetradec-l, 8-ylene; 1,4,8,11-tetraazacyclotetradec-2,3-ylene; 1, 4,8,11-tetraazacyclotetradec-2,5-ylene; 1, 4, 8, 11 - tetraazacyclotetradec-1,2-ylene; 1,4,8,11-tetraazacyclotetradec-2,2-ylidenes; 1,4,7,10-tetraazacyclododec-1, 4-ylene; 1, 4,7,10-tetraazacyclododec-1, 7-ylene; 1, 4,7, 10-tetraazacyclododec- 1,2-ylene; l, 4,7,10-tetraazacyclododec-2,3-ylene; l, 4,7,10-tetraazacyclododec-2,2-ylidene; 1, 4, 7, 10, 13 -pentaazacyclopentadec-1, 4-ylene; 1, 4, 7, 10, 13 -pentaazacyclopentadec-1, 7-ylene;

1, 4,7, 10,13-pentaazacyclopentadec-2,3-ylene; 1, 4, 7, 10, 13 -pentaazacyclopentadec-1, 2-ylene; 1, 4,7,10,13-pentaazacyclopentadec-2,2-ylidenes; 1, 4-diaza-7-thia-cyclonon-1, 4-ylene; 1, 4-diaza-7-thia-cyclonon-1,2-ylene; l, 4-diaza-7thia-cyclonon-2,3-ylene; l, 4-diaza-7-thia-cyclonon-6,8-ylene; 1,4-diaza-7-thia-cyclonone-2,2-ylidenes; 1,4-diaza-7-oxacyclonon-1, 4-ylene; 1, 4-diaza-7-oxa-cyclonon-1, 2-ylene; 1,4-diaza-7-oxa-cyclonon-2,3-ylene; 1,4-diaza-7-oxa-cyclonone-6,8-ylene; 1, 4-diaza-7-oxa-cyclonone-2,2-ylidenes; l, 4-dioxan-2,3-ylene; 1,4-dioxan-2,6-ylene; 1,4-dioxane-2,2-ylidenes; tetrahydropyran-2,3-ylene; tetrahydropyran-2,6-ylene; tetrahydropyran-2,5-ylene; tetrahydropyran-2,2-ylidene; l, 4,7-trithia-cyclonon-2,3-ylene; l, 4,7-trithia-cyclonon-2,9-ylene; and 1, 4,7-trithia-cyclonone-2,2-ylidenes,

heterocycloalkyl: selected from the group comprising: pyrrolinyl; pyrrolidinyl; morpholinyl; piperidinyl; piperazinyl; hexamethylene imine; 1,4-piperazinyl; tetrahydrothiophenyl; tetrahydrofuranyl; 1,4,7-triazacyclononanyl; 1,4,8,11-tetraazacyclotetradecanyl; 1,4,7,10,13-pentaazacyclopentadecanyl; l, 4-diaza-7-thiacyclononanyl; 1,4-diaza-7-oxa-cyclononanyl; 1,4,7,10-tetraazacyclododecanyl; 1, 4-dioxanyl; 1,4,7-trithiacyclononanyl; tetrahydropyranyl; and oxazolidinyl, wherein the heterocycloalkyl may be linked to the compound via any atom in the ring of the selected heterocycloalkyl.

halogen: selected from the group comprising: F; Cl; Br and I,

haloalkyl: selected from the group consisting of mono-, di-, tri-, poly- and perhalogenated linear and branched C 1 -C 8 -alkyl,

pseudohalogen: selected from the group consisting of -CN, -SCN, -OCN, N3, -CNO, -SeCN.

Unless otherwise stated, the following groups are more preferred groups within the general group definition:

alkyl: linear and branched C 1 -C 6 -alkyl,

long-chain alkyls: linear and branched C5-C10 alkyl, preferably C6-C8 alkyl,

alkenyl: C3-C6 alkenyl,

cycloalkyl: C6-C8-cycloalkyl,

alkoxy: Cl-C4-alkoxy, long-chain alkoxy: linear and branched C5-C10 alkoxy, preferably linear C6-C8 alkoxy,

Alkylene: selected from the group comprising: methylenes; 1,2-ethylene; 1,3-propylene; butan-2-ol-1,4-diyl; 1, 4-butylenes; cyclohexane-l, l-diyl; cyclohexane-l, 2-diyl; cyclohexane-l, 4-diyl; cyclopentane-1, 1-diyl; and cyclopentane-1, 2-diyl,

Aryl: selected from the group comprising: phenyl; biphenyl; naphthalenyl; anthracenyl; and phenanthrenyl,

Arylene: selected from the group comprising: 1, 2-phenylene; 1,3-phenylenes; 1,4-phenylene; 1,2-naphthalenylenes; 1,4-naphthalenylene; 2,3-naphthalenylenes and 1-hydroxy-2,6-phenylenes,

Heteroarylene: thiophene, pyrrole, pyridine, pyridazine, pyrimidine, indole, thienothiophene,

Halogen: selected from the group comprising: Br and Cl, more preferably Br.

In a preferred embodiment of the invention, the at least one thiophene derivative contains at least one compound of the general formula:

wherein R is selected from the group consisting of hydrogen, hydroxyl, halogen, pseudohalogen, formyl, carboxy and / or carbonyl derivatives, alkyl, long-chain alkyl, alkoxy, long-chain alkoxy, cycloalkyl, haloalkyl, aryl, arylenes, haloaryl, heteroaryl, heteroarylenes, Heterocycloalkylenes, heterocycloalkyl, haloheteroaryl, alkenyl,

Haloalkenyl, alkynyl, haloalkynyl, keto, ketoaryl, haloketoaryl, ketoheteroaryl, ketoalkyl, halo-ketoalkyl, ketoalkenyl, halo-ketoalkenyl, phosphoalkyl, phosphonates, phosphates, phosphine, phosphine oxide, phosphoryl, phosphoaryl, sulphonyl, sulphoalkyl, sulphoarenyl, sulphonates, sulphates, sulphones, amines , Polyether, silylalkyl, silylalkyloxy, where, with suitable radicals, one or more non-adjacent CH ₂ groups are independently represented by -O-, -S-, -NH-, -NR ° -, -SiR ⁰ R ⁰⁰ -, -CO -, -COO-, -OCO-, -OCO-O-, -SO ₂ -, -S-CO-, -CO-S-, -CY ^{1 =} CY ² or -C≡C- may be replaced such that O and / or S atoms are not directly connected to each other (terminal CH ₃ groups are understood as CH ₂ groups in the sense of CH ₂ -H). and wherein X and X 'independently of one another are a leaving group, preferably halogen, particularly preferably Cl, Br or I and particularly preferably Br.

According to a preferred embodiment of the present invention, the first and / or the second solution contain a solvent selected from the group of aliphatic hydrocarbons, e.g. Alkanes, in particular pentane, hexane, cyclohexane or heptane, unsubstituted or substituted aromatic hydrocarbons, such as. Benzene, toluene and xylenes, as well as ether group-containing compounds, e.g. Diethyl ether, tert-butyl methyl ether, dibutyl ether, amyl ether, dioxane and tetrahydrofuran (THF) and solvent mixtures of the abovementioned groups.

Solvents containing ether groups are preferably used in the process according to the invention. Very particular preference is tetrahydrofuran. However, it is also possible and preferred for many embodiments of the present invention to use as solvent mixtures of two or more of these solvents. For example, mixtures of the preferred solvent may be tetrahydrofuran and alkanes, e.g. Hexane (e.g., contained in commercially available solutions of starting products such as organometallic compounds). It is important in the context of the invention that the solvent, the solvents or mixtures thereof be chosen so that the thiophene derivatives used or the polymerization-active monomers are present in dissolved form in the first solution. Also suitable for the workup are halogenated aliphatic hydrocarbons, such as methylene chloride and chloroform.

In a preferred embodiment of the process according to the invention, a hydrolyzing solvent is added to the polymerization solution to terminate the reaction ("quenching"), preferably an alkyl alcohol, more preferably ethanol or methanol, most preferably methanol.

The workup is preferably carried out so that the precipitated product is filtered off, washed with the precipitant and then taken up in a solvent.

Alternatively and also preferably, purification in the soxhlet can be carried out, preferably using nonpolar solvents, such as e.g. Hexane can be used as extractant.

In many embodiments, the oligomers prepared according to the method are also distinguished by the presence of one or two leaving groups at the chain end, which in the further course can serve as substitution sites for functionalizations or end-capping reactions. According to a preferred embodiment of the present invention, after the polymerization has been carried out, however, before work-up (in particular quenching), reaction takes place with a thiophene derivative having only one leaving group. Thus, a so-called "end-capping" can be achieved.Preferably, the thiophene derivative having only one leaving group has a further functionalizable radical, preferably in the 5-position, which is preferably selected from the group phosphoalkyl, phosphonates, phosphates, phosphine, Phosphine oxide, phosphoryl, phosphoaryl, sulphonyl, sulphoalkyl, sulphoarenyl, sulphonates, sulphates, sulphones or mixtures thereof has proven to be advantageous for many applications of the present invention.

The inventive method is characterized in particular in many applications by the possibility of targeted adjustment of a desired average chain length as well as the production of products with a narrow molecular weight distribution.

Likewise provided by the invention are the oligothiophenes obtainable by the process according to the invention.

Oligothiophenes having a narrow molecular weight distribution with a polydispersity index PDI of> 1 to <3, preferably PDI <2, particularly preferably PDI> 1.1 to <1.7, are preferably obtained here.

The above-mentioned and the claimed components to be used according to the invention described in the exemplary embodiments are not subject to special exceptions in terms of their size, shape, material selection and technical design, so that the selection criteria known in the field of application can be used without restriction.

Further details, features and advantages of the subject matter of the invention will become apparent from the subclaims and from the following description of the following embodiment. example 1

Example 1 is to be understood as illustrative only and not as a limitation of the present invention, which is defined purely by the claims.

In the example, two metering streams were reacted with each other in a micromixer.

Dosing flow 1

2,5-dibromo-3-hexylthiophene 5% by weight

Ni (dppp) Cl ₂ : 0.04 wt.%, Equivalent to 0.5 mol.%

THF 94.96% by weight

Dosing flow 2:

I M ethylmagnesium bromide solution in THF

EtMgBr / Ni (dppp) CI2 / THF

326 g / mol The gross reaction equation thus corresponds to:

Experimental setup:

The metered addition of the two educt streams takes place separately from each other via piston-type syringe pumps. For intensive mixing, both starting material streams are mixed by the use of a μ mixer (Ehrmitz) and subsequently conveyed through a reaction capillary (1/16 ") and subsequently through a further residence reactor (sandwich reactor (Ehrmitz)) The capillary takes place at room temperature, in the residence reactor, on the other hand, 140 ° C. The total pressure is 6 bar in the system and is maintained at the reactor outlet via a pressure-holding valve The total residence time is 25 minutes, whereby it divides into the reaction capillary and in about 7 minutes About 18 minutes in the residence reactor. Work-up:

The reaction solution is added to methanol and the precipitated solid is filtered off. The solid is then extracted with hexane. The desired oligomer is obtained from the evaporated-in hexane phase.

Mw = 1600 g / mol

Mn = 950 g / mol

Yield 70%

Comparative Example 1

For comparison, a polymerization with higher catalyst concentration not according to the invention was carried out.

The structure and the educts corresponded to the example according to the invention, except that a catalyst concentration of 1 -mol% was selected.

A polymer was obtained with the following data:

Mw = 13200 g / mol

Mn = 5300 g / mol

Yield 71%

In comparison with the example according to the invention, it is striking that, despite the higher catalyst concentration, longer chains are obtained instead of shorter ones.

Claims

Patentannsprüche

1. A process for the polymerization of at least one thiophene derivative having at least two leaving groups to oligomers, wherein the polymerization by means of a thiophene-organometallic compound and at least one catalyst, characterized in that the method at a catalyst concentration (based on the molar amount of the thiophene used -Derivats) of> 0.01 - <0.95 mol% and a temperature of> 105 ° C - <155 ° C is performed.

2. The method of claim 1, wherein the method at a catalyst concentration (based on the molar amount of the thiophene derivative used) of> 0.05 - <0.85 mol%, preferably> 0.15 - <0.75 mol% further preferably from> 0.25 to <0.55 mol%, and most preferably from> 0.35 to <0.45 mol%.

3. The method of claim 1 or 2, wherein the method at a temperature of> 110 ⁰ C - <150 ° C, more preferably> 115 ° C - <145 ° C and most preferably> 120 ° C - <140 ° C. is carried out.

4. The method according to any one of claims 1 to 3, wherein the method at elevated pressures, preferably at> 1 - <30 bar, in particular at> 2- <15 bar and particularly preferably in the range of> 4- <10 bar, is performed ,

5. The method according to any one of claims 1 to 4, characterized in that the at least one thiophene derivative contains at least one leaving group selected from the group consisting of halogens, sulfates, sulfonates and diazo groups.

6. The method according to any one of claims 1 to 5, characterized in that the leaving groups of the at least one thiophene derivative are identical.

7. The method according to any one of claims 1 to 6, characterized in that the thiophene-organometallic compound contains at least one metal selected from the group zinc, magnesium, tin and boron.

8. The method according to any one of claims 1 to 7, characterized in that the at least one catalyst contains nickel and / or palladium.

9. The method according to any one of claims 1 to 8, characterized in that the at least one thiophene derivative contains at least one compound of the general formula:

wherein R is selected from the group consisting of hydrogen, hydroxyl, halogen, pseudohalogen, formyl, carboxy and / or carbonyl derivatives, alkyl, long-chain alkyl, alkoxy, long-chain alkoxy, cycloalkyl, haloalkyl, aryl, arylenes, haloaryl, heteroaryl, heteroarylenes, Heterocycloalkylenes, heterocycloalkyl, haloheteroaryl,

Alkenyl, haloalkenyl, alkynyl, haloalkynyl, keto, ketoaryl, halo-ketoaryl, ketoheteroaryl, ketoalkyl, halo-ketoalkyl, ketoalkenyl, halo-ketoalkenyl, phosphoalkyl, phosphonates, phosphates, phosphine, phosphine oxide, phosphoryl, phosphoaryl, sulphonyl, sulphoalkyl, sulphoarenyl, sulphonates, sulphates, sulphones , Amines, polyethers, silylalkyl, silylalkyloxy, where, with suitable radicals, one or more non-adjacent CH ₂ groups independently of one another by -O-, -S-, -NH-, -NR ° -, -SiR ⁰ R ⁰⁰ -, -CO-, -COO-, -OCO-, -OCO-O-, -SO ₂ -, -S-CO-, -CO-S-, -CY '= CY ² or -C≡C- may be replaced in such a way that O and / or S atoms are not directly connected to each other (terminal CH ₃ groups are understood as CH ₂ groups in the sense of CH ₂ -H).

and wherein X and X 'independently of one another are a leaving group, preferably halogen, particularly preferably Cl, Br or I and particularly preferably Br.

10. The method according to any one of claims 1 to 9, characterized in that the at least one catalyst contains at least one compound selected from the group consisting of nickel and palladium catalysts with ligands selected from the group tri-tert-butylphosphine, Triadamantylphosphin, 1, 3 bis (2,4,6-trimethylphenyl) -

Imidazolidinium chloride, 1,3-bis (2,6-diisopropylphenyl) -hnidazolidinium chloride or 1,3-diadamantylimidazolidinium chloride or mixtures thereof; To-

(triphenylphosphino) palladium dichloride (Pd (PPh ₃ ) Cl ₂ ), palladium (II) acetate (Pd (OAc) ₂ ), tetrakis (triphenylphosphine) palladium (Pd (PPh ₃ ) ₄ ), tetrakis (triphenylphosphine) nickel

(Ni (PPh ₃ ) ₄ ), nickel ω-acetylacetonate Ni (acac) ₂ , dichloro (2,2'-bipyridine) nickel, dibromo-bis (triphenylphosphine) nickel (Ni (PPh ₃ ) ₂ Br ₂ ), bis ( (of which diphenylphosphino) ethane nickel dichloride Ni (dppe) Cl ₂ or mixtures diphenylphosphino) propane nickel dichloride (Ni (dppp) Cl ₂₎ or bis.

11. Oligothiophene prepared according to any one of claims 1 to 10.

12. Oligothiophene according to claim 11 having a polydispersity index PDI of> 1 to <3, preferably PDI <2, more preferably PDI> 1.1 to <1.7