JP2007119379A - Method for producing dihalogenated biphenyl compounds - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a dihalogenated biphenyl compound, by which the asymmetric dihalogenated biphenyl compound can effectively be produced in an industrial scale in a high yield and in high selectivity. <P>SOLUTION: This method for producing the dihalogenated biphenyl compound comprises reacting a Grignard type compound or organic lithium type compound derived from a dihalogenated benzene with a dihalogenated benzene in the presence of a transition metal catalyst comprising a palladium compound or nickel compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing dihalogenated biphenyls by a cross-coupling reaction using a transition metal catalyst.

  Asymmetric dihalogenated biphenyls are very useful compounds for selectively synthesizing asymmetric triarylamines having a biphenyl skeleton widely used as organic electroluminescence and electrophotographic photoreceptors. Moreover, it is a very useful compound also in the use of a pharmaceutical intermediate or an industrial material.

  Conventionally, when synthesizing asymmetric dihalogenated biphenyls, a method of halogenating a halogenated biphenyl with a different halogen or a method using a Sandmeyer reaction has been mainly used. As a method of halogenating a halogenated biphenyl with a different halogen, for example, there is a method of brominating 4-chlorobiphenyl with bromine (for example, see Non-Patent Document 1). However, although this method does not specifically describe the yield, it is easily assumed that the regioselectivity of bromination and the yield are low. Moreover, since 4-chlorobiphenyl which is a raw material has toxicity, it was difficult to obtain and use industrially.

  An example of the Sandmeyer method is a method in which 4-amino-4'-bromobiphenyl is diazotized and then reacted with a copper halide reagent (see, for example, Non-Patent Document 2). However, this production method is a reaction under high temperature and oxidizing conditions, and since it is difficult to obtain an amine compound as a raw material, it has been difficult to apply on an industrial scale.

  As a solution to this problem, a method for obtaining dihalogenated biphenyls by a cross-coupling reaction using a transition metal catalyst has been proposed.

  For example, there is a method in which boronic acid is used as an organometallic reagent and synthesized by a coupling reaction with a halobenzene having a silyl group (see, for example, Non-Patent Document 3). However, application on an industrial scale is difficult because the boronic acid compound as a raw material is expensive and it is difficult to industrially obtain a halobenzene having a silyl group as a raw material.

  Further, there is a method of synthesizing by a coupling reaction with dihalogenated benzene using boronic acid as an organometallic reagent (see, for example, Patent Document 1). However, this method has very low reaction selectivity and yield, and further purification by silica gel column chromatography is performed. These are very serious problems in manufacturing on an industrial scale.

  In addition, although a method using a Grignard reagent as an organometallic reagent has been disclosed, a halogenated benzene having a trifluoromethylsulfonyl group as a coupling partner is required (for example, see Non-Patent Document 4). Since the halobenzene having a trifluoromethylsulfonyl group is very expensive, it is very difficult to adapt on an industrial scale.

  Thus, the production method described above has a major problem in efficiently producing asymmetric dihalogenated biphenyls on an industrial scale.

JP 2005-502706 A F. R. Shaw, E .; E. Turner, J.M. Chem. Soc. , 285, (1932). R. A. Benkeser, W.M. William, and O.S. H. Thomas, J.A. Am. Chem. Soc. 80, 2283-2287, (1958). Y. Han, S.H. D. Walker, and R.W. N. Young, Tetrahedron Letters. , 37, 16, 2703-2706, (1996). T. T. et al. Kamikawa, T .; Hayashi, Tetrahedron Letters. , 38, 40, 7087-7090, (1997).

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing asymmetric dihalogenated biphenyls that could not be satisfied by conventional methods. That is, an object of the present invention is to provide an efficient method for producing dihalogenated biphenyls with high yield and high selectivity using raw materials that are inexpensive and commercially available.

  As a result of intensive studies to solve the above problems, the present inventors have used a Grignard type compound or an organolithium type compound as an organometallic reagent and a dihalogenated benzene as a coupling partner, thereby achieving a high yield. The present inventors have completed a method for producing dihalogenated biphenyls that can be efficiently produced with high selectivity.

  That is, the present invention provides the following general formula (1)

（Ｘ^１，Ｘ^２は各々異なり、Ｃｌ、Ｂｒ、Ｉから選ばれるハロゲンを表す。Ｒ^１〜Ｒ^８はそれぞれ水素原子、炭素数１〜３０の直鎖、分岐若しくは環状のアルキル基、炭素数１〜３０のアルコキシ基、またはアリール基を表し、同一の置換基であってもよい。）
で表されるジハロゲン化ビフェニル類を製造する方法において、一般式（２）

(X ¹ and X ² are different from each other and represent a halogen selected from Cl, Br, and I. R ^{1 to} R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, and a carbon number. Represents an alkoxy group of 1 to 30 or an aryl group, and may be the same substituent.)
In the method for producing a dihalogenated biphenyl represented by the general formula (2)

（Ｘ^１，Ｘ^３は各々同一または異なっていてもよく、Ｃｌ、Ｂｒ、Ｉから選ばれるハロゲンを表す。Ｒ^１〜Ｒ^４はそれぞれ水素原子、炭素数１〜３０の直鎖、分岐若しくは環状のアルキル基、炭素数１〜３０のアルコキシ基、またはアリール基を表し、同一の置換基であってもよい。）
で表されるジハロゲン化ベンゼンより導かれるグリニャール型化合物または有機リチウム型化合物と一般式（３）

(X ¹ and X ³ may be the same or different and each represents a halogen selected from Cl, Br and I. R ^{1 to} R ⁴ are each a hydrogen atom, a straight chain, branched or cyclic having 1 to 30 carbon atoms. An alkyl group, an alkoxy group having 1 to 30 carbon atoms, or an aryl group, which may be the same substituent.
Grignard type compound or organolithium type compound derived from dihalogenated benzene represented by the general formula (3)

（Ｘ^２，Ｘ^４は各々同一または異なっていてもよく、Ｃｌ、Ｂｒ、Ｉから選ばれるハロゲンを表す。Ｒ^５〜Ｒ^８はそれぞれ水素原子、炭素数１〜３０の直鎖、分岐若しくは環状のアルキル基、炭素数１〜３０のアルコキシ基、またはアリール基を表し、同一の置換基であってもよい。）
で表されるジハロゲン化ベンゼンを遷移金属触媒の存在下、反応させることを特徴とするジハロゲン化ビフェニル類の製造方法に関する。

(X ² and X ⁴ may be the same or different and each represents a halogen selected from Cl, Br and I. R ^{5 to} R ⁸ are each a hydrogen atom, a straight chain, branched or cyclic having 1 to 30 carbon atoms. An alkyl group, an alkoxy group having 1 to 30 carbon atoms, or an aryl group, which may be the same substituent.
And a dihalogenated benzene represented by the following reaction in the presence of a transition metal catalyst.

  Next, the present invention will be described in more detail.

The dihalogenated biphenyls obtained by the present invention are compounds represented by the above general formula (1). In the general formula (1), R ^{1 to} R ⁸ each represent a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, or an aryl group. Examples of the linear, branched or cyclic alkyl group having 1 to 30 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, s-butyl group, t-butyl group, 2 -Methylpropyl group, n-pentyl group, s-pentyl group, 2-methylbutyl group, 3-methylbutyl group, 2,2-dimethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, n -Hexyl group, s-hexyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, 3,3-dimethylbuty Group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 2-ethylhexyl group , Cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, benzyl group and the like. Examples of the alkoxy group having 1 to 30 carbon atoms include a methoxy group, an ethoxy group, an n-propyloxy group, an i-propyloxy group, an n-butyroxy group, an s-butoxy group, a t-butyroxy group, a 2-methylpropyloxy group, an n -Pentyloxy group, s-pentyloxy group, 2-methylbutyroxy group, 3-methylbutyroxy group, 2,2-dimethylpropyloxy group, 1,1-dimethylpropyloxy group, 1,2-dimethylpropyloxy group, n-hexyloxy group, s-hexyloxy group, 2-methylpentyloxy group, 3-methylpentyloxy group, 4-methylpentyloxy group, 1,1-dimethylbutyroxy group, 2,2-dimethylbutyroxy group, 3 , 3-dimethylbutoxy group, 1,2-dimethylbutyroxy group, 1,3-dimethylbutyroxy group, 2,3-dimethylbutyroxy group, 1,2-trimethylpropyloxy group, 1,2,2-trimethylpropyloxy group, 2-ethylhexyloxy group, cyclopropyloxy group, cyclobutoxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy Group, benzyloxy group and the like. Examples of the aryl group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. X ¹ and X ² each represent a halogen selected from different Cl, Br, and I. Specific examples of the compound represented by the general formula (1) include 4-bromo-4′-chlorobiphenyl, 4-bromo-4′-iodobiphenyl, 4-chloro-4′-iodobiphenyl, 2 2,2′-dimethyl-4-bromo-4′-chlorobiphenyl, 2,2′-dimethyl-4-bromo-4′-iodobiphenyl, 2,2′-dimethyl-4-chloro-4′-iodobiphenyl, 3,3′-dimethyl-4-bromo-4′-chlorobiphenyl, 3,3′-dimethyl-4-bromo-4′-iodobiphenyl, 3,3′-dimethyl-4-chloro-4′-iodobiphenyl 3-bromo-3′-chlorobiphenyl, 3-bromo-3′-iodobiphenyl, 3-chloro-3′-iodobiphenyl, and the like.

In the compound represented by the general formula (2) used in the present invention, R ^{1 to} R ⁴ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, and 1 to 30 carbon atoms. The linear, branched or cyclic alkyl group having 1 to 30 carbon atoms is a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, s-butyl group, t-butyl group, 2-methylpropyl group, n-pentyl group, s-pentyl group, 2-methylbutyl group, 3-methylbutyl group, 2,2-dimethylpropyl group, 1,1-dimethylpropyl group Group, 1,2-dimethylpropyl group, n-hexyl group, s-hexyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1,1-dimethylbutyl group, 2,2- The Tylbutyl group, 3,3-dimethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2 -A trimethylpropyl group, 2-ethylhexyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, benzyl group, etc. can be mentioned. Examples of the alkoxy group having 1 to 30 carbon atoms include a methoxy group, an ethoxy group, an n-propyloxy group, an i-propyloxy group, an n-butyroxy group, an s-butoxy group, a t-butyroxy group, a 2-methylpropyloxy group, an n -Pentyloxy group, s-pentyloxy group, 2-methylbutyroxy group, 3-methylbutyroxy group, 2,2-dimethylpropyloxy group, 1,1-dimethylpropyloxy group, 1,2-dimethylpropyloxy group, n-hexyloxy group, s-hexyloxy group, 2-methylpentyloxy group, 3-methylpentyloxy group, 4-methylpentyloxy group, 1,1-dimethylbutyroxy group, 2,2-dimethylbutyroxy group, 3 , 3-dimethylbutoxy group, 1,2-dimethylbutyroxy group, 1,3-dimethylbutoxy group, 2,3-dimethylbutyroxy group, 1,2-trimethylpropyloxy group, 1,2,2-trimethylpropyloxy group, 2-ethylhexyloxy group, cyclopropyloxy group, cyclobutoxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy Group, benzyloxy group and the like. Examples of the aryl group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. X ¹ and X ³ each represent the same or different halogen selected from Cl, Br, and I. Specific examples of the compound represented by the general formula (2) include 1-bromo-4-chlorobenzene, 1,4-dichlorobenzene, 1,4-dibromobenzene, 1,3-dichlorobenzene, 1-chloro- 4-iodobenzene, 1-bromo-4-iodobenzene, 1-bromo-3-chlorobenzene, 1-chloro-3-iodobenzene, 2-chloro-5-bromotoluene, 2-chloro-5-iodotoluene, 2 -Bromo-5-chlorotoluene, 2-iodo-5-chlorotoluene, 2,5-dichlorotoluene and the like. Of these, 1,4-dichlorobenzene and 1-bromo-4-chlorobenzene are preferable. More preferred is 1-bromo-4-chlorobenzene.

  In the present invention, a Grignard type compound or an organic lithium type compound derived from the general formula (2) is used as the organometallic reagent. Of these, Grignard type compounds are preferred. Compared to metallic lithium, metallic magnesium is preferable because it is easily available, easy to handle, and easy to prepare into an organometallic reagent. Specific examples of the Grignard type compound derived from the general formula (2) include 4-chlorophenylmagnesium bromide, 4-chlorophenylmagnesium chloride, 4-chlorophenylmagnesium iodide, 4-bromophenylmagnesium iodide and the like. . Of these, 4-chlorophenylmagnesium bromide is preferred.

In the compound represented by the general formula (3) used in the present invention, R ^{1 to} R ⁴ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, and 1 to 30 carbon atoms. The linear, branched or cyclic alkyl group having 1 to 30 carbon atoms is a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, s-butyl group, t-butyl group, 2-methylpropyl group, n-pentyl group, s-pentyl group, 2-methylbutyl group, 3-methylbutyl group, 2,2-dimethylpropyl group, 1,1-dimethylpropyl group Group, 1,2-dimethylpropyl group, n-hexyl group, s-hexyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1,1-dimethylbutyl group, 2,2- The Tylbutyl group, 3,3-dimethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2 -A trimethylpropyl group, 2-ethylhexyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, benzyl group, etc. can be mentioned. Examples of the alkoxy group having 1 to 30 carbon atoms include a methoxy group, an ethoxy group, an n-propyloxy group, an i-propyloxy group, an n-butyroxy group, an s-butoxy group, a t-butyroxy group, a 2-methylpropyloxy group, an n -Pentyloxy group, s-pentyloxy group, 2-methylbutyroxy group, 3-methylbutyroxy group, 2,2-dimethylpropyloxy group, 1,1-dimethylpropyloxy group, 1,2-dimethylpropyloxy group, n-hexyloxy group, s-hexyloxy group, 2-methylpentyloxy group, 3-methylpentyloxy group, 4-methylpentyloxy group, 1,1-dimethylbutyroxy group, 2,2-dimethylbutyroxy group, 3 , 3-dimethylbutoxy group, 1,2-dimethylbutyroxy group, 1,3-dimethylbutoxy group, 2,3-dimethylbutyroxy group, 1,2-trimethylpropyloxy group, 1,2,2-trimethylpropyloxy group, 2-ethylhexyloxy group, cyclopropyloxy group, cyclobutoxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy Group, benzyloxy group and the like. Examples of the aryl group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. X ² and X ⁴ each represent the same or different halogen selected from Cl, Br, and I. Specific examples of the compound represented by the general formula (3) include 1-bromo-4-iodobenzene, 2-bromo-5-iodotoluene, 1,4-dibromobenzene, 2-bromo-5-iodotoluene. 2-iodo-5-bromotoluene, 2,5-dibromotoluene and the like. Of these, 1,4-dibromobenzene and 1-bromo-4-iodobenzene are preferable. More preferred is 1-bromo-4-iodobenzene.

  In the present invention, the amount of magnesium used is not particularly limited, but is 0.5 to 5.0 times mol, preferably 1.0 to 1.5 times mol, of the halogenated benzene as the raw material. A range of quantities. When the amount used is more than 5.0 times the molar amount, the Grignard reaction of both halogens proceeds, resulting in a decrease in selectivity and yield. On the other hand, when the amount is less than 0.5 times the molar amount, the halogenated benzene as the raw material remains, and this unreacted halogenated benzene increases the impurities resulting from the coupling reaction with the Grignard type compound.

  In the present invention, it is preferable to remove excess magnesium before the coupling reaction in the preparation of the Grignard type compound. This is because if there is an excess of magnesium, it reacts with the halogenated benzene of the coupling partner, and the selectivity and yield are reduced. As a method for removing magnesium, it is preferable to perform filtration under a nitrogen atmosphere or extract a reaction supernatant.

  In the present invention, a Grignard reaction solvent may or may not be used. However, in many cases, it is preferable to use a solvent because the starting halogenated benzenes are solid. As a solvent to be used, an ether solvent, an aromatic hydrocarbon solvent, or an aliphatic hydrocarbon solvent is preferable. Examples of ether solvents include tetrahydrofuran, 1,4-dioxane, cyclopentyl methyl ether, diethyl ether, diisopropyl ether, dimethoxyethane, and the like. Examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene and the like. Examples of the aliphatic hydrocarbon solvent include hexane, heptane, pentane, octane, nonane and decane. Further, the solvent may be used alone or a mixed solvent may be used.

  In the present invention, the solvent used for the coupling reaction is not particularly limited, but is an aromatic hydrocarbon solvent such as benzene, toluene, xylene, tetrahydrofuran, 1,4-dioxane, cyclopentyl methyl ether, diethyl ether, diisopropyl. Ether solvents such as ether and dimethoxyethane are preferred. Further, it may be the same as or different from the solvent in the Grignard process, or a mixed solvent may be used.

  In the present invention, the Grignard reaction temperature is in the range of 0 to 120 ° C, preferably in the range of 20 to 80 ° C. When the reaction temperature is lower than 0 ° C., the reaction rate decreases and the production efficiency decreases. On the other hand, if the reaction temperature is higher than 120 ° C., a side reaction such as Grignard reaction of the other halogen proceeds and a by-product is generated during the coupling reaction, which is not preferable. The coupling reaction temperature is in the range of -20 to 100 ° C, preferably in the range of 0 to 60 ° C. When the reaction temperature is lower than −20 ° C., the reaction rate is lowered and the production efficiency is lowered. When the reaction temperature is higher than 100 ° C., impurities resulting from the reaction between the product and the Grignard compound increase, which is not preferable.

  In the present invention, the embodiment of the reaction comprises two steps of the Grignard reaction and the coupling reaction, but it may be carried out by a one-pot reaction. In the coupling reaction, the Grignard compound may be dropped into the halogenated benzene represented by the above general formula (3), or the halogenated benzene may be dropped into the Grignard compound. May be.

  In this reaction, the pressure during the reaction is not particularly limited. For example, the absolute pressure is in the range of 0 to 0.1 MPa, preferably under atmospheric pressure because no special production equipment is required.

In the present invention, a transition metal catalyst is used as the catalyst used in the cross-coupling reaction. As the transition metal catalyst, a palladium compound or a nickel compound is used. Specific examples of the palladium compound include Pd (OAc) ₂ , (CH ₃ CN) ₂ PdCl ₂ , Pd ₂ (dba) ₃ , Pd / C, PdCl _{2 and the} like. Further, specific examples of nickel compounds include Ni (acac) ₂ and NiCl ₂ . In the above compounds, Ac represents an acetyl group, acac represents an acetylacetone group, and dba represents a dibenzylideneacetone group.

The transition metal catalyst used in the present invention may be a two-component catalyst composed of a palladium compound or a nickel compound and a phosphine compound. The catalyst used may be either one already prepared from a phosphine compound and a metal compound outside the reaction system, or one prepared by a method in which a phosphine compound and a metal compound coexist in the reaction system. Specific examples of the catalyst comprising a nickel compound and a phosphine compound include Ni (dppe) Cl ₂ , Ni (dppp) Cl ₂ , Ni (PPh ₃ ) ₂ Cl ₂ , Ni (PPh ₃ ) ₂ Br ₂ , Ni (PPh ₃ ) ₄ , Ni (P (t-Bu) ₃ ) _2, etc. are mentioned. Specific examples of the catalyst composed of a palladium compound and a phosphine compound are Pd (dppf) Cl ₂ , Pd (dppe) Cl ₂ , Pd (PPh ₃ ) ₄ , Pd (PPh ₃ ) ₂ Cl ₂ , Pd (P (t -Bu) ₃ ) _{2 and the} like. In the above compound, dppe represents a diphenylphosphinoethane group, dppp represents a diphenylphosphinopropane group, PPh represents a triphenylphosphine group, and t-Bu represents a t-butyl group.

  In the present invention, the amount of the transition metal catalyst used is not particularly limited, but is in the range of 0.001 to 10.0 mol% with respect to the halogenated benzene represented by the general formula (3). . Preferably it is the range of 0.01-1.0 mol%. Moreover, the usage-amount of said phosphine compound is although it does not specifically limit, It is preferable that it is the range of 0.5-10 times mole amount with respect to the metal in a metal compound. More preferably, the molar amount is 1.0 to 5.0 times.

  According to the present invention, by using an inexpensive organometallic reagent and dihalogenated benzene as raw materials, it is possible to efficiently produce asymmetric dihalogenated biphenyls with high yield and high selectivity on an industrial scale. it can.

  The present invention will be described in more detail with reference to the following examples. However, these examples show the outline of the present invention, and the present invention is not limited to these examples.

[Measurement of reaction yield and conversion]
The apparatus used for the gas chromatography measurement is shown below.

Device: GC-17A (manufactured by Shimadzu Corporation)
Column: Capillary column NEUTRA BOND-5 (manufactured by GL Sciences)
(0.32mm ID x 30m)
Detector: FID (hydrogen flame ionization detector)
Example 1
A 100 ml flask equipped with a thermometer and a condenser was charged with 1.31 g of magnesium, 39.3 g of tetrahydrofuran, and 168 μl of ethyl bromide in a nitrogen atmosphere, and the temperature was raised to 60 ° C., followed by stirring for 30 minutes. Next, 20.0 g of a tetrahydrofuran solution of 7.92 g of 1,4-dichlorobenzene was added dropwise over 30 minutes. After completion of dropping, aging was performed at 60 ° C. for 17.5 hours. When the reaction solution was analyzed by gas chromatography, the conversion was 96.7% and the selectivity was 86.9%. The reactor was then cooled to room temperature and 441 mg of Pd (dppf) Cl ₂ was added. Further, 38.9 g of a toluene solution of 12.7 g of 1-bromo-4-iodobenzene was dropped over 50 minutes using a dropping funnel. After completion of dropping, the mixture was aged at room temperature for 39 hours. The reaction liquid was analyzed by gas chromatography, and the reaction yield and conversion rate were determined. As a result, 61.2% of 4-bromo-4′-chlorobiphenyl, which was the target product, was produced, and the raw material for the coupling reaction The conversion was 90.9% based on 1-bromo-4-iodobenzene.

  Thereafter, 55.2 g of water was added to the reaction mixture, liquid separation operation was performed, and the obtained organic layer was concentrated. The obtained crude crystals were washed with hexane and dried to obtain 9.64 g of 4-bromo-4'-chlorobiphenyl (yield 80.3%, purity 87.6%).

Example 2
In a 100 ml flask equipped with a thermometer and a condenser, 441 mg (18.15 mmol) of magnesium, 13.1 g of tetrahydrofuran, and 56 μl of ethyl bromide were charged in a nitrogen atmosphere, and the temperature was raised to 60 ° C., followed by stirring for 30 minutes. Next, 7.54 g of a tetrahydrofuran solution of 3.16 g (16.5 mmol) of 1-bromo-4-chlorobenzene was added dropwise over 30 minutes. After completion of the dropping, aging was performed at 60 ° C. for 24 hours. When the reaction solution was analyzed by gas chromatography, the reaction conversion rate was 100% and the selectivity was 99.6%.

The reactor was then cooled to room temperature and 135 mg of Pd (dppf) Cl ₂ was added. Furthermore, 13.41 g of a toluene solution of 4.67 g (16.5 mmol) of 1-bromo-4-iodobenzene was dropped using a dropping funnel over 50 minutes. After completion of dropping, the mixture was aged at room temperature for 39 hours. The reaction solution was analyzed by gas chromatography, and the reaction yield and conversion rate were determined. As a result, 78.5% of the desired product, 4-bromo-4′-chlorobiphenyl, was produced. The conversion was 85.0% based on 1-bromo-4-iodobenzene.

Then, 20.0 g of water was added to the reaction mixture, liquid separation operation was performed, and the obtained organic layer was concentrated. When the obtained crude crystals were washed with hexane and dried, 3.99 g (yield 90.5, purity 87.6%) of 4-bromo-4′-chlorobiphenyl was obtained.

Claims (6)

General formula (1)

(X ¹ and X ² are different from each other and represent a halogen selected from Cl, Br, and I. R ^{1 to} R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, and a carbon number. Represents an alkoxy group of 1 to 30 or an aryl group, and may be the same substituent.)
In the method for producing a dihalogenated biphenyl represented by the general formula (2)

(X ¹ and X ³ may be the same or different and each represents a halogen selected from Cl, Br and I. R ^{1 to} R ⁴ are each a hydrogen atom, a straight chain, branched or cyclic having 1 to 30 carbon atoms. An alkyl group, an alkoxy group having 1 to 30 carbon atoms, or an aryl group, which may be the same substituent.
Grignard type compound or organolithium type compound derived from dihalogenated benzene represented by the general formula (3)

(X ² and X ⁴ may be the same or different and each represents a halogen selected from Cl, Br and I. R ^{5 to} R ⁸ are each a hydrogen atom, a straight chain, branched or cyclic having 1 to 30 carbon atoms. An alkyl group, an alkoxy group having 1 to 30 carbon atoms, or an aryl group, which may be the same substituent.
A process for producing dihalogenated biphenyls, characterized in that the dihalogenated benzene represented by the formula is reacted in the presence of a transition metal catalyst. In the general formulas (1) to (3), R ^{1 to} R ⁸ are all hydrogen atoms, and in the general formula (1), X ¹ and X ² are present at the 4-position and 4′-position of biphenyl, and The general formula (2), wherein X ¹ is para-position to X ³ , and in general formula (3), X ² is para-position to X ⁴ . Of producing dihalogenated biphenyls. In the general formulas (1) to (3), X ¹ = Br, X ² = Cl or X ¹ = Cl, X ² = Br, wherein the dihalogenated biphenyls according to claim 1 or 2, Production method. The method for producing dihalogenated biphenyls according to claim 1, wherein, in the general formula (2), X ¹ = Cl, X ³ = Br or X ¹ = X ³ = Cl. The method for producing dihalogenated biphenyls according to claim 1, wherein the transition metal catalyst used is a palladium compound or a nickel compound. 6. The method for producing dihalogenated biphenyls according to claim 5, wherein the transition metal catalyst used is a two-component catalyst comprising a palladium compound or a nickel compound and a phosphine compound.