WO2006011879A1

WO2006011879A1 - Process for forming an aromatic amine compound

Info

Publication number: WO2006011879A1
Application number: PCT/US2004/021137
Authority: WO
Inventors: Lynda Woedy Mc Garry; Paul Patrick Spara; Ruizheng Wang
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 2004-06-30
Filing date: 2004-06-30
Publication date: 2006-02-02
Anticipated expiration: 2006-12-30

Abstract

A process for forming an aromatic amine product comprises the steps of (a) combining an aromatic primary or secondary initial amine with an aromatic halide compound in the presence of a palladium complex and a phosphine compound catalyst to form a mixture; (b) heating the mixture to a first temperature of at least 60°C; (c) adding a base material to the heated mixture; and (d) maintaining the temperature of the mixture at or above the first temperature for a period of time sufficient to form as a product an aromatic substituted form of the aromatic primary or secondary initial amine. The process provides products of high purity in good yields.

Description

PROCESS FOR FORMING AN AROMATIC AMINE COMPOUND

FIELD OF THE INVENTION This invention relates to the field of organic syntheses and to a process for forming a secondary or tertiary aromatic amine compound using a palladium/phosphine catalyst.

BACKGROUND OF THE INVENTION

Aromatic amine compounds are very useful materials and consequently there is a continuing need for improved synthetic methods that allow their preparation in an economical manner and in high purity. In particular, tertiary aromatic amine compounds have found use in electroluminescent (EL) devices such as organic light-emitting diodes (OLEDs).

While organic EL devices have been known for over two decades, their performance limitations have represented a barrier to many desirable applications. In simplest form, an organic EL device is comprised of an anode for hole injection, a cathode for electron injection, and an organic medium sandwiched between these electrodes to support charge recombination that yields emission of light. These devices are also commonly referred to as organic light- emitting diodes, or OLEDs. Representative of earlier organic EL devices are Gurnee et al. US 3,172,862, issued Mar. 9, 1965; Gurnee US 3,173,050, issued Mar. 9, 1965; Dresner, "Double Injection Electroluminescence in Anthracene", RCA Review, 30, 322-334, (1969); and Dresner US 3,710,167, issued Jan. 9, 1973. The organic layers in these devices, usually composed of a polycyclic aromatic hydrocarbon, were very thick (much greater than 1 μm). Consequently, operating voltages were very high, often greater than 100V.

More recent organic EL devices include an organic EL element consisting of extremely thin layers (e.g., less than 1.0 μm) between the anode and the cathode. Herein, the term "organic EL element" encompasses the layers between the anode and cathode. Reducing the thickness lowered the resistance of the organic layer and has enabled devices that operate at much lower voltage, hi a basic two-layer EL device structure, described first in US 4,356,429, one organic layer of the EL element adjacent to the anode is specifically chosen to transport holes, and therefore, it is referred to as the hole-transporting layer, and the other organic layer is specifically chosen to transport electrons, and is referred to as the electron-transporting layer. Recombination of the injected holes and electrons within the organic EL element results in efficient electroluminescence.

There have also been proposed three-layer organic EL devices that contain an organic light-emitting layer (LEL) between the hole-transporting layer and electron-transporting layer, such as that disclosed by Tang et al (J. Applied Physics, 65, Pages 3610-3616, (1989)). The light-emitting layer commonly consists of a host material doped with a guest material, also known as a dopant. Still further, there has been proposed in US 4,769,292 a four-layer EL element comprising a hole-injecting layer (HIL), a hole-transporting layer (HTL), a light- emitting layer (LEL) and an electron transport/injection layer (ETL). These structures have resulted in improved device efficiency.

Since these early inventions, further improvements in device materials have resulted in improved performance in attributes such as color, stability, luminance efficiency and manufacturability, e.g., as disclosed in US 5,061,569, US 5,409,783, US 5,554,450, US 5,593,788, US 5,683,823, US 5, 908,581, US 5,928,802, US 6,020,078, and US 6,208,077, amongst others.

While not always necessary, it is often useful to include a hole- transporting layer in an OLED device. The hole-transporting layer of the organic EL device contains at least one hole-transporting compound such as an aromatic tertiary amine, where the latter is understood to be a compound containing at least one trivalent nitrogen atom that is bonded only to carbon atoms, at least one of which is a member of an aromatic ring, hi one form the aromatic tertiary amine can be an arylamine, such as a monoarylamine, diarylamine, triarylamine, or a polymeric arylamine. Exemplary monomelic triarylamines are illustrated by Klupfel et al. US 3,180,730. Other suitable triarylamines substituted with one or more vinyl radicals and/or comprising at least one active hydrogen containing group are disclosed by Brantley et al US 3,567,450 and US 3,658,520. A more desirable class of aromatic tertiary amines include at least two aromatic tertiary amine moieties as described in US 4,720,432 and US 5,061,569. US 5,061,569, US 6,074,734, and US 6,242,1 15 describe the use tertiary amines such as tetrarylbenzidine derivatives as hole-transporting materials. These materials can also be used in light-emitting layers as host materials or in combination with other host materials, for example, see WO 02/20693. It is desirable to use very pure materials in EL devices to ensure long operating lifetimes.

Suitable tertiary amine derivatives can be synthesized by various methods including the Ullmann condensation which involves the coupling of aryl halides with copper, for example see J. March, Advanced Organic Chemistry, 3^r Ed., John Wiley and Sons, NY, 1985, page 597. S. Turner and coworkers in US 4,764,625 describe a process of preparing a tertiary amine by the condensation of an amine compound and an iodoaryl compound. The reaction is carried out in the presence of potassium hydroxide, and a copper catalyst at a temperature between 120 ⁰C to about 190 ⁰C, however these are harsh conditions and can cause substantial decomposition of sensitive compounds.

One especially desirable method for the synthesis of tertiary amines that does not require high temperatures or severe reaction conditions involves a metal catalyzed coupling reaction between a halogenated aromatic group and an amine substituted aromatic group, for example see US 5,576,460. This synthetic method has received considerable attentions, for a review see S. Buchwald, J. Organomet. Chem., 576, 125, (1999).

Y. Nishiyama, et al. describe a similar process for the preparation of tertiary amines in US 5,929,281, in which the aryl halide, the arylamine, the palladium catalysis, and the base are combined and then the mixture is heated to effect the reaction to the tertiary amine, hi some cases (Example 10) the catalysis is not added initially to the reaction mixture, but added after the mixture is heated to 80⁰C.

Hosokawa and coworkers, US 2003/0072966, describe a process for producing a material for an organic electroluminescence device, which comprises reacting a primary amine or a secondary amine and certain aryl halogen substituted compounds and a base in the presence of a catalyst comprising a phosphine compound and a palladium compound. In the examples of this process the aryl halide, the arylamine, the catalysis, and the base are combined and then the mixture is heated to form the tertiary amine. There remains a need for improvements on these synthetic methods especially in order to produce materials of high purity in good yield for use in the electronic industry such as in the manufacture of EL devices.

SUMMARY OF THE INVENTION The invention provides a process for forming an aromatic amine product comprising the steps of

(a) combining an aromatic primary or secondary initial amine with an aromatic halide compound in the presence of a palladium complex and a phosphine compound catalyst to form a mixture; (b) heating the mixture to a first temperature of at least 60°C;

(c) adding a base material to the heated mixture; and

(d) maintaining the temperature of the mixture at or above the first temperature for a period of time sufficient to form as a product an aromatic substituted form of the aromatic primary or secondary initial amine. The process provides product amines of high purity in good yield.

DETAILED DESCRIPTION OF THE INVENTION

The invention process is summarized above. The process is useful to provide aromatic secondary and tertiary amines. The process is especially useful to provide tertiary aromatic amines and in particular polycyclic aromatic molecules that contain at least two tertiary aromatic amine groups. The process is valuable for producing materials that can be used in electronic devices such as EL devices.

The process for forming a new aromatic amine comprises starting with an initial aromatic primary or secondary amine, examples include N- phenylamine, N, N-diphenylamine, N, N-di(2-naphthyl)amine, N-(2-naphthyl)-N- (l-naphthyl)amine. Amines of this type can be often purchased from commercial sources, such as Aldrich Chemical Co., or made by literature procedures, hi one preferred embodiment the starting aromatic amine is a secondary amine represented by Formula (1).

-\

N- H

^Ar2/ (l)

In Formula (1) Ar¹ and Ar² represent independently selected aromatic groups. Suitably Ar¹ and Ar² represent independently selected aryl groups, for example, phenyl groups, naphthyl groups or pyridyl groups.

The starting primary or secondary amine compound is mixed with an aromatic halide compound. In one suitable embodiment the aromatic halide compound is an arylhalide wherein the halide is an iodo, bromo, or chloro substituent. Illustrative examples include a bromophenyl group, a iodophenyl group, a 1-bromonaphthyl group, a 2-iodonaphthyl group, and a 4-chloro-l,l- biphenyl group. Desirably, the arylhalide is an iodo or bromo compound.

In general, if the starting amine is a primary amine then using approximately 1 equivalent of the halide compound can form a secondary amine. Thus it is preferable that the halide compound be in the range of about 0.9 to 1.1 mole equivalents to that of the amount of the primary amine. If the starting amine is a primary amine then using approximately 2 equivalents or more of the halide compound can form a tertiary amine. For example the halide compound may be present at 1.8, 2.0, 2.2, 3, or even greater mole equivalents relative to the amine compound. If the starting amine is a secondary amine then using approximately

1 equivalent or more of the halide compound can form a tertiary amine. Thus it is suitable that the arylhalide be present in the range of about equal or greater than that of the amount of the secondary amine. For example the arylhalide may be 1.5, 2.0, 2.2, 3, or even greater mole equivalents relative to the amine compound. If the halide compound includes two or more active coupling substituents, the amount of the halide compound can be adjusted accordingly. For example, a halide compound that includes two iodo, bromo, or chloro groups may be reacted with approximately two equivalents of a secondary amine to form a compound that has two tertiary amine substituents.

In one desirable embodiment the halide compound has at least two halogen substituents. Suitably the halide compound may be represented by Formula (2).

X₁-Ar-X₂ (2).

hi Formula (2), Xj and X₂ independently represent an iodo, bromo, or chloro substituent. In one suitable embodiment, Xj and X₂ independently represent an iodo or a bromo substituent. Ar represents a divalent aromatic group, for example, a group such as a phenylene group, a biphenylene group, and a naphthylene group.

The reaction mixture also includes a palladium complex as a catalyst. The palladium catalyst may be derived from a convenient palladium source, for example, palladium halides, including PdCl₂, PdBr₂, palladium carboxylates, including Pd(OAc)₂, Pd(CF₃CO₂)₂ and palladium (II) acetylacetonoate, palladium (II) bis(benzonitrile)dichloride, and tris(dibenzylideneacetone)dipalladium (0). Where Pd(II) ions are derived from these sources, the Pd(II) maybe converted to Pd(O) in situ during the course of the process, hi one desirable embodiment the catalyst is palladium diacetate.

The quantity of palladium used in the process is typically in the range 0.0001 to 10 mole %, more commonly 0.005 to 5 mole %, and often 0.01 to 3 mole %, relative to the quantity of amine compound.

A phosphine compound is also present in the process. Suitable phosphines can be obtained from commercial sources such as Aldrich Chemical Company or synthesized by methods know in the literature. Phosphines are believed to act as ligands to the palladium thereby forming a more effective catalyst for the coupling reaction, hi one embodiment, suitable phosphines are substituted by three groups. The groups may be aromatic groups or nonaromatic groups or combinations thereof. In one suitable embodiment the groups include aryl groups such as phenyl groups. Desirably the groups may include alkyl groups such as /-butyl groups or cycloalkyl groups. Examples of useful phosphines are triphenylphosphine, tricyclohexylphosphine and tri-t-butylphosphine. Suitable phosphine compounds may comprise more than one phosphine group. The phosphine compound may comprise a salt, for example tri(t-butyl)phosphonium fluoroborate.

In one embodiment, the quantity of phosphine ligand used in the process may be such that the molar ratio of palladium to phosphorus is from 6 to 0.1, more typically form 5.0 to 0.5 and commonly from 5.0 to 3.0.

In one embodiment the reaction is carried out in a solvent. A suitable solvent is one that dissolves the reactants, at least partially, and does not interfere with the reaction. For example, aromatic solvents such as toluene and xylene are useful.

Desirably the reaction mixture is stirred during the reaction process in order to ensure good mixing of the reactants.

The mixture formed by combining an aromatic primary or secondary amine with an aromatic halide compound in the presence of a palladium complex and a phosphine compound catalyst is then heated to a first temperature of at least 60°C. In one embodiment the mixture is heated to at least 60°C but to less than 85°C.

After heating the mixture, a base material is added. For example, the base material may be an organic base, such as Na(t-BuO) or K(t-BuO). Alternatively the base material may be selected from alkali metal and alkaline earth metal phosphates such as Na₃PO₄ and K₃PO₄, and CsCO₃. Desirably the base is Na(t-BuO). The base material may be dissolved in a solvent prior to addition such as an aromatic hydrocarbon, such as toluene, or other solvent such as tetrahydrofuran. In one embodiment the base material is added over a period of at least 5 minutes, commonly over a period of at least 15 minutes, and typically over a period of at least 25 minutes depending on the scale of the reaction.

In one embodiment, the quantity of base used in the process may be such that the ratio of equivalents of base to the amine derivative is from 3 to 0.1 , more typically from 1.5 to 0.5 and commonly from 1.3 to 0.7.

After the base material is added, the temperature of the mixture is maintained at or above the first temperature for a period of time to form a substantial amount an amine product. In one suitable embodiment the reaction is maintained at a temperature of between 65 ⁰C and 95 ⁰C and commonly between 75 ⁰C and 85 ⁰C.

Optimum reaction times can be determined by monitoring the reaction. For example, by removing aliquots of the reaction mixture periodically and by using thin-layer-chromatography (TLC) or high-performance-liquid chromatography (HPLC) analysis one can determine the amount of reactants present, e.g. unreacted starting amine, and one can determine the amount of product formed. In this manner the progress of the reaction can be monitored. Typically the reaction times are 1 to 24 h, but maybe shorter or longer.

The optimum amount of the reactants relative to the initial amine compound as well as the optimum reaction conditions can be determined by doing designed experiments to maximize yield and minimize side-products. The concentration of the reactants, the temperature of the reaction, and the time of the reaction can all be varied to determine preferred values, for example see D. C. Montgomery, Design And Analysis Of Experiments, 5th ed, John Wiley, New York, (2001).

The product amine can be isolated and purified if necessary. Purification maybe done by well-known methods such as sublimation, distillation, crystallization or column chromatography.

The product amine is an aromatic secondary or tertiary amine. In one aspect of the invention the product aromatic amine is a tertiary amine. A desirable class of aromatic tertiary amines are those that include at least two aromatic tertiary amine moieties as described in US 4,720,432 and US 5,061 ,569. Such compounds include those represented by structural formula (A).

^Ql-_G-^Q2

wherein Qi and Q₂ are independently selected aromatic tertiary amine moieties and G is a linking group such as an arylene, cycloalkylene, or alkylene group of a carbon to carbon bond. In one embodiment, at least one Of Q₁ or Q₂ contains a polycyclic fused ring structure, e.g., a naphthalene. When G is an aryl group, it is conveniently a phenyl ene, biphenylene, or naphthalene moiety.

A useful class of triarylamines satisfying structural formula (A) and containing two triarylamine moieties is represented by structural formula (B):

R2

B Ri- C- R₃

R4 where R₁ and R₂ each independently represents a hydrogen atom, an aryl group, or an alkyl group or R₁ and R₂ together represent the atoms completing a cycloalkyl group; and R₃ and R₄ each independently represents an aryl group, which is in turn substituted with a diaryl substituted amino group, as indicated by structural formula (C), wherein R₅ and R₆ are independently selected aryl groups. In one embodiment, at least one of R₅ or R₆ contains a polycyclic fused ring structure, e.g., a naphthalene.

R₅

Another class of useful aromatic tertiary amines is the tetraaryldiamines. Desirable tetraaryldiamines include two diarylamino groups, such as indicated by formula (C), linked through an arylene group. Useful tetraaryldiamines include those represented by formula (D). ^R7. . Rs

N Are N'

D Ar n R₉

Wherein each Are is an independently selected arylene group, such as a phenylene or anthracene moiety, n is an integer of from 1 to 4, and Ar, R₇, R₈, and R₉ are independently selected aryl groups. In a typical embodiment, at least one of Ar, R₇, R₈, and R₉ is a polycyclic fused ring structure, e.g., a naphthalene.

The various alkyl, alkylene, aryl, and arylene moieties of the foregoing structural formulae (A), (B), (C), (D), can each in turn be substituted. Typical substituents include alkyl groups, alkoxy groups, aryl groups, aryloxy groups, and halide such as fluoride, chloride, and bromide. The various alkyl and alkylene moieties typically contain from about 1 to 6 carbon atoms. The cycloalkyl moieties can contain from 3 to about 10 carbon atoms, but typically contain five, six, or seven ring carbon atoms~e.g., cyclopentyl, cyclohexyl, and cycloheptyl ring structures. The aryl and arylene moieties are usually phenyl and phenylene moieties. hi one suitable embodiment the product aromatic amine is represented by Formula (3).

hi Formula (3), Ar₁ and Ar₂ may be the same or different and each represents an independently selected aromatic group, such as a phenyl group or a naphthyl group. Each d independently represents an independently selected substituent such as a methyl group or a phenyl group. Each n independently is 0-4.

Illustrative examples of product aromatic amine compounds are listed below.

AA-I 4,4'-Bis[N-(l -naphthyl)-N-(2-naρhthyl)amino]biρhenyl AA-2 4,4'-Bis[iV-(l -naphthyl)-N-phenylamino]biphenyl (ΝPB) AA-3 1 , 1 -Bis(4-di_:p-tolylaminophenyl)-4-methylcyclohexane

AA-4 1 , 1 -Bis(4-di-/?-tolylaminophenyl)-4-phenylcyclohexane

AA-5 1 , 1 -Bis(4-di-/?-tolylaminophenyl)-3 -phenylpropane

AA-6 iV,N,7V,N'-tetraphenyl-4,4^m-diamino-l ,1 ':4',1 ":4",1 ^m- quateφhenyl

AA-7 Bis(4-dimethylamino-2-methylphenyl)phenylmethane

AA-8 1 ,4-Bis[2-[4-[N,N-di(>-toly)amino]phenyl]vinyl]benzene

AA-9 N,N,iV,N'-Tetra-_jp-tolyl-4,4'-diaminobiρlienyl

AA- 10 N,N,N,N -Tetraphenyl-4,4'-diaminobiρhenyl

AA-11 N,N,ΛP,N'-tetra-l-naphthyl-4,4^l-dianiinobiphenyl

AA- 12 N,N,ΛP,NMetra-2-naphthyl-4,4'-diaminobiphenyl

AA-13 4,4'-Bis[N-(l -naphthyl)-N-phenylamino]p4erphenyl

AA- 14 4,4'-Bis[N-(2-naphthyl)-N-phenylamino]biphenyl

AA-15 4,4'-Bis[N-(3-acenaphthenyl)-N-phenylamino]biphenyl

AA-16 1 ,5-Bis[N-(l -naphthyl)-N-phenylamino]naphthalene

AA- 17 4,4'-Bis[N-(9-anthryl)-N-phenylamino]biphenyl

AA-18 4,4'-Bis[N-(l -anthryl)-7V-phenylamino]-jc-terphenyl

AA- 19 4,4'-Bis[N-(2-phenanthryl)-iV-phenylamino]biphenyl

AA-20 4,4'-Bis[7V-(8-fluoranthenyl)-N-phenylamino]biphenyl

AA-21 4,4'-Bis[iV-(2-pyrenyl)-iV-phenylaniino]biphenyl

AA-22 4,4'-Bis[N-(2-naphthacenyl)-iV-phenylamino]biplienyl

AA-23 4,4'-Bis[N-(2-perylenyl)-N-phenylamino]biphenyl

AA-24 4,4'-Bis[iV-(l-coronenyl)-N-phenylamino]biphenyl

AA-25 2,6-Bis(di-j!?-tolylamino)naphthalene

AA-26 2,6-Bis[di-( 1 -naphthyl)amino]naphthalene

AA-27 2,6-Bis[N-(l -naphthyl)-N-(2-naphthyl)amino]naphthalene

AA-28 N₁N₁N₁N -Tetra(2-naphthyl)-4,4"-diamino-^-terphenyl

AA-29 4,4'-Bis {N-phenyl-N-[4-(l -naphthyl)- phenyl] amino } biphenyl

AA-30 2,6-Bis[N,N-di(2-naphthyl)amino]fluorene

AA-31 4,4'-Bis[N-(3 -methylphenyl)-N-ρhenylamino]biphenyl AA-32 N-( 1 -naphthyl)-N-(2-naphthyl)amine AA-33 N-( 1 -naphthyl)-/V-phenylamine

Unless otherwise specifically stated, use of the term "substituted" or "substituent" means any group or atom other than hydrogen. Additionally, when the term "group" is used, it means that when a substituent group contains a substitutable hydrogen, it is also intended to encompass not only the substituent's unsubstituted form, but also its form further substituted with any substituent group or groups as herein mentioned, so long as the substituent does not destroy properties necessary for device utility. Suitably, a substituent group may be halogen or may be bonded to the remainder of the molecule by an atom of carbon, silicon, oxygen, nitrogen, phosphorous, sulfur, selenium, or boron. The substituent maybe, for example, halogen, such as chloro, bromo or fluoro; nitro; hydroxyl; cyano; carboxyl; or groups which may be further substituted, such as alkyl, including straight or branched chain or cyclic alkyl, such as methyl, trifluoromethyl, ethyl, t-butyl, 3-(2,4-di-t-pentylphenoxy) propyl, and tetradecyl; alkenyl, such as ethylene, 2-butene; alkoxy, such as methoxy, ethoxy, propoxy, butoxy, 2-methoxyethoxy, sec-butoxy, hexyloxy, 2-ethylhexyloxy, tetradecyloxy, 2-(2,4-di-t-pentylphenoxy)ethoxy, and 2-dodecyloxyethoxy; aryl such as phenyl, 4-t-butylphenyl, 2,4,6-trimethylphenyl, naphthyl; aryloxy, such as phenoxy, 2- methylphenoxy, alpha- or beta-naphthyloxy, and 4-tolyloxy; carbonamido, such as acetamido, benzamido, butyramido, tetradecanamido, alpha-(2,4~di-t-penty\- phenoxy)acetamido, α/p/zα-(2,4-di-t-pentylphenoxy)butyramido, α^?/zα-(3- pentadecylphenoxy)-hexanamido, α//?Λfl-(4-hydroxy-3-t-butylphenoxy)- tetradecanamido, 2-oxo-pyrrolidin-l-yl, 2-oxo-5-tetradecylpyrrolin-l-yl, N- methyltetradecanamido, N-succinimido, N-phthalimido, 2,5-dioxo-l-oxazolidinyl, 3-dodecyl-2,5-dioxo-l -imidazolyl, and N-acetyl-N-dodecylamino, ethoxycarbonylamino, phenoxycarbonylamino, benzyloxycarbonylamino, hexadecyloxycarbonylamino, 2,4-di-t-butylphenoxycarbonylamino, phenylcarbonylamino, 2,5-(di-t-pentylphenyl)carbonylamino,/7-dodecyl- phenylcarbonylamino, j?-tolylcarbonylamino, N-methylureido, NN- dimethylureido, N-methyl-N-dodecylureido, N-hexadecylureido, NN- dioctadecylureido, NN-dioctyl-N-ethylureido, N-phenylureido, NN- diphenylureido, N-phenyl-N-jo-tolylureido, N-(m-hexadecylphenyl)ureido, NN- (2,5-di-t-pentylphenyl)-N-ethylureido, and /-butylcarbonamido; sulfonamido, such as methylsulfonamido, benzenesulfonamido, p-tolylsulfonamido, £>- dodecylberizenesulfonamido, N-methyltetradecylsulfonamido, NN-dipropyl- sulfamoylamino, and hexadecylsulfonamido; sulfamoyl, such as N- methylsulfamoyl, N-ethylsulfamoyl, N,N-dipropylsulfamoyl, N- hexadecylsulfamoyl, NN-dimethylsulfamoyl, N-[3-(dodecyloxy)propyl]sulfamoyl, N-[4-(2,4-di-t-pentylphenoxy)butyl]sulfamoyl, N-methyl-N-tetradecylsulfamoyl, and N-dodecylsulfamoyl; carbamoyl, such as N-methylcarbamoyl, NN- dibutylcarbamoyl, N-octadecylcarbamoyl, N-[4-(2,4-di-t- pentylphenoxy)butyl]carbamoyl, N-methyl-N-tetradecylcarbamoyl, and NN- dioctylcarbamoyl; acyl, such as acetyl, (2,4-di-t-amylphenoxy)acetyl, phenoxycarbonyl, jc-dodecyloxyphenoxycarbonyl methoxycarbonyl, butoxycarbonyl, tetradecyloxycarbonyl, ethoxycarbonyl, benzyloxycarbonyl, 3- pentadecyloxycarbonyl, and dodecyloxycarbonyl; sulfonyl, such as methoxysulfonyl, octyloxysulfonyl, tetradecyloxysulfonyl, 2- ethylhexyloxysulfonyl, phenoxysulfonyl, 2,4-di-t-pentylphenoxysulfonyl, methylsulfonyl, octylsulfonyl, 2-ethylhexylsulfonyl, dodecylsulfonyl, hexadecylsulfonyl, phenylsulfonyl, 4-nonylphenylsulfonyl, andp-tolylsulfonyl; sulfonyloxy, such as dodecylsulfonyloxy, and hexadecylsulfonyloxy; sulfinyl, such as methylsulfmyl, octylsulfinyl, 2-ethylhexylsulfinyl, dodecylsulfinyl, hexadecylsulfinyl, phenylsulfinyl, 4-nonylphenylsulfinyl, and/7-tolylsulfinyl; thio, such as ethylthio, octylthio, benzylthio, tetradecylthio, 2-(2,4-di-t- pentylphenoxy)ethylthio, phenylthio, 2-butoxy-5-t-octylphenylthio, and p- tolylthio; acyloxy, such as acetyloxy, benzoyloxy, octadecanoyloxy, p- dodecylamidobenzoyloxy, N-phenylcarbamoyloxy, N-ethylcarbamoyloxy, and cyclohexylcarbonyloxy; amine, such as phenylanilino, 2-chloroanilino, diethylamine, dodecylamine; imino, such as 1 (N-phenylimido)ethyl, N- succinimido or 3-benzylhydantoinyl; phosphate, such as dimethylphosphate and ethylbutylphosphate; phosphite, such as diethyl and dihexylphosphite; a heterocyclic group, a heterocyclic oxy group or a heterocyclic thio group, each of which may be substituted and which contain a 3 to 7 membered heterocyclic ring composed of carbon atoms and at least one hetero atom selected from the group consisting of oxygen, nitrogen, sulfur, phosphorous, or boron, such as 2-furyl, 2- thienyl, 2-benzimidazolyloxy or 2-benzothiazolyl; quaternary ammonium, such as triethyl ammonium; quaternary phosphonium, such as triphenylphosphonium; and silyloxy, such as trimethylsilyloxy.

If desired, the substituents may themselves be further substituted one or more times with the described substituent groups. The particular substituents used may be selected by those skilled in the art to attain the desired desirable properties for a specific application and can include, for example, electron-withdrawing groups, electron-donating groups, and steric groups. When a molecule may have two or more substituents, the substituents may be joined together to form a ring such as a fused ring unless otherwise provided. Generally, the above groups and substituents thereof may include those having up to 48 carbon atoms, typically 1 to 36 carbon atoms and usually less than 24 carbon atoms, but greater numbers are possible depending on the particular substituents selected. The invention and its advantages can be better appreciated by the following examples.

Example 1 : Inventive Large Scale Preparation of 4,4'-Bis[N-(l-naphthyl)-N-(2- naphthyl)amino]biphenyl (AA-I).

N-l-Νaphthyl-N-2-naphthylamine (12.7 kg, 47.14 mol), 4,4'- diiodobiphenyl (9.8 Kg, 24.2 mol), palladium (II) acetate (0.150 Kg, 0.663 mol), and toluene (140 Kg) were combined in a vessel. Nitrogen was bubbled through the mixture for 30 min to remove oxygen. The catalyst, tri-f-butylphosphine (0.6 Kg, 3.0 mol) was added as a 20 % by weight solution in toluene with stirring and the mixture was heated to 75°C over a 1 h period. Sodium t-butoxide (29.4 Kg, 61.3 mol) was added over 25 min as a 20 % by weight solution in THF and the reaction mixture was heated to 80⁰C and held at that temperature for 3 h. Ethyl acetate (85 Kg) was then added and the mixture was cooled to 75°C. Cellulose fiber (Supercel, 5 Kg) was added and the mixture was stirred and then filtered. The filtrate was washed with HCl solution and then dried with magnesium sulfate and filtered. The solvent was removed under vacuum to yield a thin oil. Toluene was added to the oil and the mixture was then added to hot cyclohexane (2800 Kg) to obtain a solution. Silica gel and carbon were added to the mixture, which was stirred for 16 h at 80°C and then filtered

The filtrate was distilled to 1/10 volume and methanol was added. After cooling to 10°C, the product was allowed to crystallize for 12 hours and collected. The crude product was dissolved in hot cyclohexane, treated with silica gel, and stirred for 16 h at 70⁰C and then filtered. The filtrate was distilled to 1/10 volume and methanol was added. After cooling to 10⁰C, the product was allowed to crystallize for 12 hours and collected. The product was then slurried in isopropyl alcohol. The isopropyl alcohol was distilled and replenished with fresh isopropyl alcohol. This procedure was repeated seven times. Then methanol was added, and the methanol was removed by distillation and replenished with fresh methanol. This was repeated two times. The product mixture was cooled to 5O⁰C and the product was collected and dried at 75°C in a vacuum oven to afford 4,4'-Bis[N-(l -naphthyl)-N-(2- naphthyl)amino]biphenyl (7.0 Kg, 43.5 % yield), analysis by high-performance liquid-chromatography indicated that this material was 99% pure and had a halide content of less than 0.002 % by weight and a palladium content of less than 0.0003 % by weight.

Example 2: Inventive Small-Scale Preparation of AA-I.

N-(l-Naphthyl)-N-(2-naphthyl)amine (64.08 g, 0.238 mol), 4,4'- diiodobiphenyl (48.28g, 0.118 mol), and 0.8 g (2.4 mmol) of palladium acetate were added to a 1 L vessel, and 300 mL of dry toluene (that had been sparged with nitrogen) was added to the solids under a nitrogen atmosphere with stirring. The solution was put under vacuum, and then flushed with nitrogen to ensure that all oxygen was removed. This was repeated twice. To this suspension was added 16.8 mL (8.0 mmol) of a 20 % by weight solution of tri-t-butylphosphine in toluene via syringe. The reaction mixture was stirred vigorously under nitrogen and slowly heated to 75 ⁰C over a 1 h period. A solution of nitrogen-purged 20 % sodium t- butoxide in THF (164 mL, 0.30 mol) was added to the 75 ⁰C reaction mixture over 30 min. The reaction was stirred at 80 ⁰C for 3 h. A sample of the reaction mixture (1-1) was then taken for analysis by liquid chromatography (LC), and the results are reported in Table 1.

Example 3: Comparative Preparation of AA- 1.

N-(l-Naphthyl)-N-(2-naphthyl)amine (40.41 g, 0.15 mol), and 4,4'- diiodobiphenyl (31.5g, 0.078 mol) were added to a 1 L vessel and 600 mL of dry toluene (that had been sparged with nitrogen) was added to the solids under a nitrogen atmosphere with stirring. A solution of nitrogen-purged 20 % by weight sodium t- butoxide (90.0 g, 0.187 mol) in THF was added quickly to the reaction mixture. The solution was put under vacuum and then flushed with nitrogen to ensure that all oxygen was removed. This was repeated twice. To this suspension was added 11.5 mL (0.0096 mol) of a 20 % by weight solution of tri-t- butylphosphine in toluene via syringe, followed by palladium acetate (0.52g, 0.0024 mol) as a solution in dry toluene. These were prepared under inert conditions and added to the reaction mixture under nitrogen. The reaction mixture was stirred vigorously under nitrogen, and slowly heated to 75 ⁰C over a 1 h period. The reaction mixture was stirred at 75 ⁰C for 3 h. A sample of the reaction mixture (C-I) was then taken for analysis by liquid chromatography (LC), and the results are reported in Table 1.

Table 1

Table 1 shows the LC data measured for samples 1-1 and C-I . The number of impurities corresponds to the number of peaks in the chromatograph that are not due to the desired product. The level of the impurities corresponds to the sum of the area under all the impurity peaks divided by the area under all the peaks including the product peak multiplied by 100. The yield of the product, AA-I , was determined in a similar manner. It can be seen from Table 1 that the N,N,N'N'-tetraarylamine, AA-I, prepared according to the inventive process is formed in higher yield and greater purity than when synthesized by the comparative process. Embodiment of this invention may provide amines of high purity and yield. The aromatic amine compounds synthesized according to this invention maybe incorporated in an EL device. In one embodiment the aromatic amine materials are included in a hole-transporting layer of an EL device.

Claims

CLAIMS:

1. A process for forming an aromatic amine product comprising the steps of

(a) combining an aromatic primary or secondary initial amine with an aromatic halide compound in the presence of a palladium complex and a phosphine compound catalyst to form a mixture;

(b) heating the mixture to a first temperature of at least 60⁰C;

(c) adding a base material to the heated mixture; and

(d) maintaining the temperature of the mixture at or above the first temperature for a period of time sufficient to form as a product an aromatic substituted form of the aromatic primary or secondary initial amine.

2. The process according to claim 1 wherein the initial amine is a secondary amine substituted with two independently selected aromatic groups.

3. The process according to claim 2 wherein the independently selected aromatic groups are naphthyl groups.

4. The process according to claim 1 wherein the initial aromatic amine is represented by Formula (1),

N- H Ar^ _{(1 )}

wherein Ar¹ and Ar² represent independently selected aromatic groups.

5. The process according to claim 1 wherein the aromatic halide compound is an arylhalide.

1 0

6. The process according to claim 5 wherein the arylhalide is an aryliodide or an arybromide.

7. The process according to claim 5 wherein the arylhalide compound is substituted with two halogens.

8. The process according to claim 5 wherein the arylhalide is a

4, 4'-diiodo-l,l-biphenyl group or a 4, 4'-dibromo-l,l-biphenyl group.

9. The process according to claim 1 wherein the aromatic halide compound is represented by Formula (2),

X₁-A-X₂ (2)

wherein:

X] and X₂ independently represent an iodo, bromo, or chloro substituent; and

A represents a divalent aromatic group.

10. The process according to claim 1 wherein the palladium complex comprises palladium in the oxidation state of (II).

11. The process of claim 1 wherein the palladium catalysis comprises palladium diacetate.

12. The process according to claim 1 wherein the phosphine compound comprises a trialkylphosphine compound, a triarylphosphine compound or a diphosphine substituted compound.

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13. The process according to claim 1 wherein the phosphine compound comprises tri(£-butyl)phosphine.

14. The process according to claim 1 wherein the phosphine compound comprises a salt.

15. The process according to claim 1 wherein the phosphine compound comprises rri(t-butyl)phosρhonium fluoroborate.

16. The process according to claim 1 wherein the mixture includes a solvent comprising an aromatic hydrocarbon.

17. The process according to claim 1 wherein the mixture is heated to a first temperature that is above 70 ⁰C.

18. The process according to claim 1 wherein the mixture is heated to a first temperature that is below 85 ⁰C.

19. The process according to claim 1 wherein the base material is added over a period of at least 5 minutes.

20. The process according to claim 1 wherein the base material is added over a period of at least 15 minutes.

21. The process according to claim 1 wherein the base material is added over a period of at least 25 minutes.

22. The process according to claim 1 wherein the base material comprises a metal alkoxide.

23. The process according to claim 1 wherein the base material comprises a sodium t-butoxide.

24. The process according to claim 1 wherein the reaction is maintained at a temperature of between 70 ⁰C and 90 ⁰C.

25. The process according to claim 1 wherein the product amine comprises a tertiary amine having three independently selected aromatic substituents.

26. The process according to claim 1 wherein the amine product comprises at least two tertiary amines.

27. The process according to claim 1 wherein the product amine is represented by Formula (3),

wherein: each Ar¹ represents an independently selected aromatic group; each Ar² represents an independently selected aromatic group; each d independently represents an independently selected substituent; and each n independently is 0-4.

28. The process according to claim 27 wherein Ar¹ and Ar² are different and each represents an independently selected aromatic group.

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29. The process according to claim 27 wherein Ar¹ and Ar² each represents an independently selected naphthyl group.