JP2004091361A

JP2004091361A - Method for producing 2-naphthol derivative, and intermediate thereof

Info

Publication number: JP2004091361A
Application number: JP2002253191A
Authority: JP
Inventors: Tetsuo Kusumoto; 楠本　哲生; Yoshitaka Saito; 斉藤　佳孝; Sadao Takehara; 竹原　貞夫
Original assignee: Dainippon Ink and Chemicals Co Ltd
Current assignee: DIC Corp
Priority date: 2002-08-30
Filing date: 2002-08-30
Publication date: 2004-03-25
Anticipated expiration: 2022-08-30
Also published as: JP4314799B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily and inexpensively producing a 2-naphthol derivative without using a fluorinating agent, while the conventional method for producing the same is complicated and necessitates the use of an expensive fluorinating agent. <P>SOLUTION: The method for producing the 2-naphthol derivative represented by general formula (III) comprises reacting a brominating agent with a tetrahydronaphthalene derivative represented by general formula (I) to give a compound represented by general formula (II) and reducing this compound. Thus, the 2-naphthol derivative, conventionally produced by a complicated process, is produced industrially easily and inexpensively. As no fluorinating agent is used, the amount of by-products such as a decomposition product of the fluorinating agent is reduced and the aimed product is easily purified. The 2-naphthol derivative is very useful as a synthetic intermediate for a liquid crystal. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は２−ナフトール誘導体の製造及びその製造中間体に関する。
【０００２】
【従来の技術】
塩素原子またはフッ素原子を含有する２−ナフトール誘導体は以下に示すような種々の液晶化合物（特開２０００−０６３３０５号公報）
【０００３】
【化９】

の製造中間体として有用である。しかし、置換基の種類や位置によっては製造法が知られておらず、製造方法が知られているものについても以下のような複雑な工程を経由していた。（特開２００１−０１０９９４号公報）
【０００４】
【化１０】

【０００５】
更に、上記方法では、四フッ化硫黄、ＤＡＳＴ（ジエチルアミノ三フッ化硫黄）、ＡＣＣＵＦＬＯＲ　ＮＦＳｉ（ＡｌｌｉｅｄＳｉｇｎａｌ製）等の高価格なフッ素化剤を複数回用いなければならず、フッ素化剤に由来する副生成物を取り除く工程を必要としていた。そのため塩素原子またはフッ素原子を含有する２−ナフトール誘導体の工業的に容易で安価な製造方法が求められている。
【０００６】
【発明が解決しようとする課題】
本発明が解決しようとする課題は、塩素原子またはフッ素原子を含有する２−ナフトール誘導体の、フッ素化剤を使用しない容易で安価な製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明は、上記課題を解決するために鋭意検討した結果、テトラヒドロナフタレノンを臭素化剤で酸化し、生成する１−ブロモ−２−ナフトール誘導体を還元することによって２−ナフトール誘導体が容易に得られることを見出し、本発明を完成するに至った。
【０００８】
すなわち本発明は、一般式（Ｉ）
【化１１】

（式中、Ｘ^１、Ｘ^２、Ｘ^３およびＸ^４は、おのおの独立して水素原子、フッ素原子または塩素原子を表すが、Ｘ^１、Ｘ^２、Ｘ^３およびＸ^４のうち少なくともひとつはフッ素原子または塩素原子である。）で表されるテトラヒドロナフタレノンに臭素化剤を作用させ、一般式（ＩＩ）
【０００９】
【化１２】

（式中、Ｘ^１、Ｘ^２、Ｘ^３およびＸ^４は、おのおの独立して水素原子、フッ素原子または塩素原子を表すが、Ｘ^１、Ｘ^２、Ｘ^３およびＸ^４のうち少なくともひとつはフッ素原子または塩素原子である。）で表される１−ブロモ−２−ナフトール誘導体または、一般式（ＩＩ）及び一般式（ＩＩＩ）
【００１０】
【化１３】

（式中、Ｘ^１、Ｘ^２、Ｘ^３およびＸ^４は、おのおの独立して水素原子、フッ素原子または塩素原子を表すが、Ｘ^１、Ｘ^２、Ｘ^３およびＸ^４のうち少なくともひとつはフッ素原子または塩素原子である。）で表される化合物の混合物を製造した後、還元することによる一般式（ＩＩＩ）で表される２−ナフトール誘導体の製造方法および、その中間体である一般式（ＩＩ）で表される１−ブロモ−２−ナフトール誘導体を提供する。
【００１１】
【発明の実施の形態】
本製造法における臭素化剤としては、臭素、Ｎ−ブロモこはく酸イミドまたは１，３−ジブロモ−５，５−ジメチルヒダントインを用いることができるが、臭素が好ましい。臭素は１モル等量から２モル等量以上の過剰量を用いることができる。ここで、臭素２モル等量以下では、一般式（ＩＩ）および一般式（ＩＩＩ）の混合物または一般式（Ｉ）、一般式（ＩＩ）および一般式（ＩＩＩ）の混合物となり、大過剰用いるとさらに臭素化が進行する可能性があるが、一般式（ＩＩ）の還元による一般式（ＩＩＩ）の製造工程において、一般式（ＩＩ）及び一般式（ＩＩＩ）の混合物を用いることは問題なく、さらに臭素化が進行した化合物も還元によって一般式（ＩＩＩ）に変換できることから問題はない。ただし、操作の簡便性や還元条件、収率等から、臭素は１．５〜３モル等量が好ましい。
【００１２】
本製造法における化合物（Ｉ）と臭素との反応において、溶媒を用いることが好ましく、その溶媒としてはジクロロメタン、クロロホルム、四塩化炭素、１，２−ジクロロエタン、１，１−ジクロロエタン、１，１，１−トリクロロエタン、１，１，２−トリクロロエタン等の塩素化炭化水素、ペンタン、ヘキサン、シクロヘキサン、ヘプタン、オクタン、デカヒドロナフタレン等の飽和炭化水素、ジエチルエーテル、メチル−ｔ−ブチルエーテル、ジイソプロピルエーテル、ジブチルエーテル、テトラヒドロフラン、１，４−ジオキサン等のエーテル系溶媒、ベンゼン、トルエン、キシレン、クロロベンゼン等の芳香族化合物などを単独でまたは混合して用いることができるが、なかでも塩素化炭化水素が好ましい。
【００１３】
反応温度は溶媒の凝固点から溶媒還流温度で行うことができるが、−７８℃から６０℃が好ましく、−２０℃から４０℃が特に好ましい。
【００１４】
本製造法における化合物（ＩＩ）の還元触媒としては、Ｒｈ、Ｒｕ、Ｐｔ、Ｐｄ、ＩｒまたはＯｓの金属あるいはこれらの金属化合物が挙げられる。また、これらの金属および金属化合物は１種を単独でまたは２種以上を併用してもよい。
【００１５】
例えば、Ｐｄの金属およびその化合物の具体例としては、パラジウム炭素、パラジウム末、酸化パラジウム、塩化パラジウム、臭化パラジウム、ヨウ化パラジウム、テトラアンミンパラジウム塩化物、テトラアンミンパラジウム硝酸塩、テトラアンミンパラジウム酢酸塩などのパラジウム塩あるいはテトラキス（トリフェニルホスフィン）パラジウム、ビス（アセチルアセトナト）パラジウムなどのパラジウム錯体が挙げられる。
また、前述のＰｄに換えて、Ｒｈ、Ｒｕ、Ｐｔ、Ｒｅ、Ｉｒ、Ｏｓの金属および／またはその金属化合物についても同様のものが挙げられる。
また、これらの金属および金属化合物は１種を単独でまたは２種以上を併用してもよく、さらにシリカゲルやアルミナ等を添加したりこれらに担持させても良い。
中でも、Ｐｄの金属またはその金属化合物が好ましい。
【００１６】
本反応は水素雰囲気下から水素２００気圧（１９．６　ＭＰａ）下で行うことができるが、水素雰囲気下から水素９．８　ＭＰａ（１００気圧）下が好ましく、反応容器の使用の簡便さから水素雰囲気下から水素３．９　ＭＰａ（４０気圧）下が特に好ましい。
【００１７】
本反応には各種溶媒を用いることができる。反応溶媒としては、メタノール、エタノール、１−プロパノール、２−プロパノール、１−ブタノール、２−ブタノール、２−メチル−１−プロパノール等のアルコール類、酢酸等の有機酸類、ジエチルエーテル、メチル−ｔ−ブチルエーテル、テトラヒドロフラン等のエーテル類、酢酸エチル、酢酸メチル、酢酸ブチル等のエステル類、ペンタン、ヘキサン、ヘプタン、オクタン等の飽和炭化水素類、ベンゼン、トルエン、キシレン等のベンゼン類、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド等のアミド類などを単一または混合して用いることができるが、アルコール類、有機酸類およびそれらを含有する混合溶媒が好ましい。また、本反応では臭化水素が発生するので、トリエチルアミン、ジエチルアミン、ジイソプロピルアミン、トリブチルアミン、ピリジン、アニリン等のアミン類を添加することが好ましい。
【００１８】
本製造法における化合物（ＩＩ）の還元にはラネーネッケル、希土類系水素吸蔵合金など水素含有金属や、スズや亜鉛と塩酸等を用いることもできる。
【００１９】
本製造法における化合物（ＩＩ）の還元には、亜硫酸ナトリウム、亜硫酸カリウム、亜硫酸カルシウム、亜硫酸水素ナトリウム、亜硫酸水素カリウムなどの亜硫酸塩を用いることもできる。
【００２０】
本製造法における出発物質である化合物（Ｉ）は一般式（ＩＶ）
【化１４】

（式中、Ｘ^１、Ｘ^２、Ｘ^３およびＸ^４は、おのおの独立して水素原子、フッ素原子または塩素原子を表すが、Ｘ^１、Ｘ^２、Ｘ^３およびＸ^４のうち少なくともひとつはフッ素原子または塩素原子である。）で表されるフェニル酢酸誘導体を塩化チオニル等の塩素化剤を用いて酸塩化物とした後、塩化アルミニウム等のルイス酸存在下、エチレンと反応させることによって容易に製造できる。
【００２１】
【実施例】
以下、実施例を挙げて本発明を更に詳述するが、本発明はこれらの実施例に限定されるものではない。化合物の構造は、核磁気共鳴スペクトル（ＮＭＲ）、質量スペクトル（ＭＳ）及び赤外吸収スペクトル（ＩＲ）により確認した。
【００２２】
（実施例１）５，６，７−トリフルオロ−２−ナフトールの合成（１）
【化１５】

（１−１）１−ブロモ−５，６，７−トリフルオロ−２−ナフトールの合成
５，６，７−トリフルオロ−１，２，３，４−テトラヒドロナフタレン−２−オン　３０　ｇのジクロロメタン　９０　ｍｌ溶液に、氷冷下、臭素　１６．１　ｍｌのジクロロメタン　４５　ｍｌ溶液を１時間かけて滴下し、さらに１時間攪拌した。反応溶液に水を加え、さらに、亜硫酸水素ナトリウム水溶液にあけ、有機層を分取し、水、飽和炭酸水素ナトリウム水溶液、飽和食塩水の順に洗浄し、無水硫酸ナトリウムで乾燥後、濃縮し、１−ブロモ−５，６，７−トリフルオロ−２−ナフトール４１．５　ｇを得た。
ＭＳ　ｍ／ｚ　２７７　（Ｍ^＋＋２），　２７５　（Ｍ^＋）
【００２３】
（１−２）５，６，７−トリフルオロ−２−ナフトールの合成
２　Ｌのオートクレーブに１−ブロモ−５，６，７−トリフルオロ−２−ナフトール　４１．５　ｇ、５％パラジウム―炭素（５０％含水）１２　ｇ、トリエチルアミン　４１　ｍｌおよびエタノール　４００　ｍｌを加え、室温、水素　０．３９２　ＭＰａ（４　ｋｇ／ｃｍ^２）下で２時間攪拌した。反応液をろ過し、ろ液を濃縮後、残渣にトルエン　３００　ｍｌ、水　３００　ｍｌを加え、攪拌後有機層を分取した。水層をトルエンで抽出し、有機層を合わせ、水、１０％塩酸、飽和炭酸水素ナトリウム水溶液、飽和食塩水で洗浄後、無水硫酸ナトリウムで乾燥後、濃縮し、５，６，７−トリフルオロ−２−ナフトール　２７　ｇを得た。
ＭＳ　ｍ／ｚ　１９８　（Ｍ^＋，　１００）
^１Ｈ　ＮＭＲ　（ＣＤＣｌ_３）　δ　１．０−５．０　（ｂｒｏａｄ，　１　Ｈ），　７．０７　（ｓ，　１　Ｈ），　７．１−７．３　（ｍ，　２　Ｈ），７．９４　（ｄ，　Ｊ　＝　９．０　Ｈｚ，　１　Ｈ）
【００２４】
（実施例２）５，６，７−トリフルオロ−２−ナフトールの合成（２）
１−ブロモ−５，６，７−トリフルオロ−２−ナフトール　５　ｇ、亜硫酸ナトリウム　９．１　ｇ、メタノール　６５　ｍｌおよび水　４５　ｍｌを加え、４時間加熱還流した。反応液に水　２００　ｍｌを加え、氷冷し、析出物をろ別、乾燥し、５，６，７−トリフルオロ−２−ナフトール　３．７　ｇを得た。
【００２５】
（実施例３）７，８−ジフルオロ−２−ナフトールの合成
【化１６】

実施例１と同様な条件下、５，６，７−トリフルオロ−１，２，３，４−テトラヒドロナフタレン−２−オンの代わりに、７，８−ジフルオロ−１，２，３，４−テトラヒドロナフタレン−２−オンを用いて、１−ブロモ−７，８−ジフルオロ−２−ナフトールおよび７，８−ジフルオロ−２−ナフトールを得た。
１−ブロモ−７，８−ジフルオロ−２−ナフトール　ＭＳ　ｍ／ｚ　２５８　（Ｍ^＋＋２），　２６０　（Ｍ^＋）
７，８−ジフルオロ−２−ナフトール　　１８０　（Ｍ^＋）
【００２６】
（実施例４）７，８−ジフルオロ−２−ナフトールの合成
【化１７】

実施例１と同様な条件下、５，６，７−トリフルオロ−１，２，３，４−テトラヒドロナフタレン−２−オンの代わりに、５，７−ジフルオロ−１，２，３，４−テトラヒドロナフタレン−２−オンを用いて、１−ブロモ−５，７−ジフルオロ−２−ナフトールおよび５，７−ジフルオロ−２−ナフトールを得た。
【００２７】
本発明の製造方法は、工程が短い上、高価なフッ素化剤を用いないため副生成物が少なく目的物の精製方法が容易であった。
【００２８】
【発明の効果】
本発明により、これまで製造が複雑であった２−ナフタレン誘導体が、工業的に容易にかつ安価に製造できるようになった。更に、本発明の製造方法はフッ素化剤を用いないためフッ素化剤の分解物等の副生成物が少なく目的物の精製も容易であった。この２−ナフタレン誘導体誘導体は、液晶用合成中間体として極めて有用である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to production of 2-naphthol derivatives and intermediates for producing the same.
[0002]
[Prior art]
Various naphthol derivatives containing a chlorine atom or a fluorine atom include various liquid crystal compounds as shown below (JP-A-2000-063305).
[0003]
Embedded image

Useful as an intermediate for the production of However, depending on the type and position of the substituent, the production method is not known, and the production method is known through the following complicated steps. (Japanese Patent Application Laid-Open No. 2001-010994)
[0004]
Embedded image

[0005]
Further, in the above method, a high-priced fluorinating agent such as sulfur tetrafluoride, DAST (diethylamino sulfur trifluoride), and ACCUFLOR NFSi (manufactured by AlliedSignal) must be used a plurality of times. A step to remove the product was required. Therefore, there is a demand for an industrially easy and inexpensive method for producing a 2-naphthol derivative containing a chlorine atom or a fluorine atom.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide an easy and inexpensive method for producing a 2-naphthol derivative containing a chlorine atom or a fluorine atom without using a fluorinating agent.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present invention oxidizes tetrahydronaphthalenone with a brominating agent and reduces the resulting 1-bromo-2-naphthol derivative to easily obtain a 2-naphthol derivative. And found that the present invention was completed.
[0008]
That is, the present invention provides a compound represented by the general formula (I):
Embedded image

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine A tetrahydronaphthalenone represented by the general formula (II):
[0009]
Embedded image

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine 1-bromo-2-naphthol derivative represented by the general formula (II) and the general formula (III):
[0010]
Embedded image

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine After producing a mixture of compounds represented by the formula (III) or a chlorine atom, a method for producing a 2-naphthol derivative represented by the general formula (III) by reduction, and an intermediate represented by the general formula ( A 1-bromo-2-naphthol derivative represented by II) is provided.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
As a brominating agent in the present production method, bromine, N-bromosuccinimide or 1,3-dibromo-5,5-dimethylhydantoin can be used, but bromine is preferred. Bromine can be used in excess of 1 molar equivalent to 2 molar equivalents or more. Here, when the amount of bromine is equal to or less than 2 molar equivalents, a mixture of the general formulas (II) and (III) or a mixture of the general formulas (I), (II) and (III) is used. Although bromination may further proceed, there is no problem using a mixture of general formula (II) and general formula (III) in the production process of general formula (III) by reduction of general formula (II). Furthermore, there is no problem since the compound that has been brominated can be converted to the general formula (III) by reduction. However, from the viewpoint of simplicity of operation, reduction conditions, yield, and the like, 1.5 to 3 molar equivalents of bromine are preferable.
[0012]
In the reaction between compound (I) and bromine in the present production method, it is preferable to use a solvent, and the solvent may be dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethane, 1,1,1. Chlorinated hydrocarbons such as 1-trichloroethane and 1,1,2-trichloroethane, saturated hydrocarbons such as pentane, hexane, cyclohexane, heptane, octane and decahydronaphthalene, diethyl ether, methyl-t-butyl ether, diisopropyl ether, diisopropyl ether Ether solvents such as butyl ether, tetrahydrofuran, and 1,4-dioxane, and aromatic compounds such as benzene, toluene, xylene, and chlorobenzene can be used alone or in combination. Among them, chlorinated hydrocarbons are preferable.
[0013]
The reaction can be carried out at a solvent reflux temperature from the freezing point of the solvent, preferably from -78 ° C to 60 ° C, particularly preferably from -20 ° C to 40 ° C.
[0014]
Examples of the reduction catalyst for compound (II) in the present production method include metals of Rh, Ru, Pt, Pd, Ir, and Os, and metal compounds thereof. These metals and metal compounds may be used alone or in combination of two or more.
[0015]
For example, specific examples of the metal of Pd and its compounds include palladium carbon, palladium powder, palladium oxide, palladium chloride, palladium bromide, palladium iodide, tetraamminepalladium chloride, tetraamminepalladium nitrate, and palladium such as tetraamminepalladium acetate. Examples thereof include salts and palladium complexes such as tetrakis (triphenylphosphine) palladium and bis (acetylacetonato) palladium.
Further, in place of the above-mentioned Pd, the same metals and / or metal compounds of Rh, Ru, Pt, Re, Ir, and Os can be used.
These metals and metal compounds may be used alone or in combination of two or more. Further, silica gel, alumina or the like may be added or carried on these.
Among them, a metal of Pd or a metal compound thereof is preferable.
[0016]
This reaction can be carried out from a hydrogen atmosphere to 200 atm (19.6 MPa) of hydrogen, preferably from a hydrogen atmosphere to 9.8 MPa (100 atm) of hydrogen. It is particularly preferable that the pressure be from the atmosphere to 3.9 MPa (40 atm) of hydrogen.
[0017]
Various solvents can be used in this reaction. Examples of the reaction solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and 2-methyl-1-propanol; organic acids such as acetic acid; diethyl ether; Ethers such as butyl ether and tetrahydrofuran; esters such as ethyl acetate, methyl acetate and butyl acetate; saturated hydrocarbons such as pentane, hexane, heptane and octane; benzenes such as benzene, toluene and xylene; N, N-dimethyl Amides such as formamide and N, N-dimethylacetamide can be used alone or as a mixture, but alcohols, organic acids and mixed solvents containing them are preferred. Since hydrogen bromide is generated in this reaction, it is preferable to add amines such as triethylamine, diethylamine, diisopropylamine, tributylamine, pyridine, and aniline.
[0018]
For the reduction of compound (II) in the present production method, a hydrogen-containing metal such as Raney-Neckel or a rare earth-based hydrogen storage alloy, or tin, zinc and hydrochloric acid can also be used.
[0019]
In the reduction of the compound (II) in the present production method, a sulfite such as sodium sulfite, potassium sulfite, calcium sulfite, sodium bisulfite, potassium bisulfite and the like can also be used.
[0020]
Compound (I), which is a starting material in the present production method, has the general formula (IV)
Embedded image

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine The phenylacetic acid derivative represented by the formula (1) is converted to an acid chloride using a chlorinating agent such as thionyl chloride, and then reacted with ethylene in the presence of a Lewis acid such as aluminum chloride. Can be manufactured.
[0021]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The structure of the compound was confirmed by a nuclear magnetic resonance spectrum (NMR), a mass spectrum (MS) and an infrared absorption spectrum (IR).
[0022]
Example 1 Synthesis of 5,6,7-trifluoro-2-naphthol (1)
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(1-1) Synthesis of 1-bromo-5,6,7-trifluoro-2-naphthol 5,6,7-trifluoro-1,2,3,4-tetrahydronaphthalen-2-one 30 g of dichloromethane To a 90 ml solution was added dropwise a solution of 16.1 ml of bromine in 45 ml of dichloromethane over 1 hour under ice cooling, and the mixture was further stirred for 1 hour. Water was added to the reaction solution, further poured into an aqueous solution of sodium hydrogen sulfite, the organic layer was separated, washed with water, an aqueous solution of saturated sodium hydrogen carbonate and saturated saline in this order, dried over anhydrous sodium sulfate, and concentrated. 41.5 g of -bromo-5,6,7-trifluoro-2-naphthol were obtained.
MS m / z 277 (M ⁺⁺ 2), 275 (M ⁺ )
[0023]
(1-2) Synthesis of 5,6,7-trifluoro-2-naphthol 1-bromo-5,6,7-trifluoro-2-naphthol 41.5 g, 5% palladium-carbon was placed in a 2 L autoclave. 12 g of (50% water), 41 ml of triethylamine and 400 ml of ethanol were added, and the mixture was stirred at room temperature under 0.392 MPa (4 kg / cm ² ) of hydrogen for 2 hours. The reaction solution was filtered, and the filtrate was concentrated. Then, 300 ml of toluene and 300 ml of water were added to the residue, and the mixture was stirred and the organic layer was separated. The aqueous layer was extracted with toluene, and the organic layers were combined, washed with water, 10% hydrochloric acid, a saturated aqueous solution of sodium hydrogencarbonate, and saturated saline, dried over anhydrous sodium sulfate, and concentrated to give 5,6,7-trifluoro. 27 g of -2-naphthol was obtained.
MS m / z 198 (M ⁺ , 100)
¹ H NMR (CDCl ₃ ) δ 1.0-5.0 (broad, 1 H), 7.07 (s, 1 H), 7.1-7.3 (m, 2 H), 7.94 ( d, J = 9.0 Hz, 1 H)
[0024]
Example 2 Synthesis of 5,6,7-trifluoro-2-naphthol (2)
5 g of 1-bromo-5,6,7-trifluoro-2-naphthol, 9.1 g of sodium sulfite, 65 ml of methanol and 45 ml of water were added, and the mixture was heated under reflux for 4 hours. 200 ml of water was added to the reaction solution, the mixture was ice-cooled, and the precipitate was separated by filtration and dried to obtain 3.7 g of 5,6,7-trifluoro-2-naphthol.
[0025]
Example 3 Synthesis of 7,8-difluoro-2-naphthol

Under the same conditions as in Example 1, instead of 5,6,7-trifluoro-1,2,3,4-tetrahydronaphthalen-2-one, 7,8-difluoro-1,2,3,4-one was used. 1-Bromo-7,8-difluoro-2-naphthol and 7,8-difluoro-2-naphthol were obtained using tetrahydronaphthalen-2-one.
1-Bromo-7,8-difluoro-2-naphthol MS m / z 258 (M ⁺⁺ 2), 260 (M ⁺ )
7,8-difluoro-2-naphthol 180 (M ⁺ )
[0026]
Example 4 Synthesis of 7,8-difluoro-2-naphthol

Under the same conditions as in Example 1, instead of 5,6,7-trifluoro-1,2,3,4-tetrahydronaphthalen-2-one, 5,7-difluoro-1,2,3,4- 1-Bromo-5,7-difluoro-2-naphthol and 5,7-difluoro-2-naphthol were obtained using tetrahydronaphthalen-2-one.
[0027]
In the production method of the present invention, the steps are short, and since an expensive fluorinating agent is not used, the amount of by-products is small and the purification method of the target substance is easy.
[0028]
【The invention's effect】
According to the present invention, a 2-naphthalene derivative, whose production has been complicated, can be industrially easily and inexpensively produced. Furthermore, since the production method of the present invention does not use a fluorinating agent, there are few by-products such as decomposition products of the fluorinating agent, and the purification of the target product was easy. This 2-naphthalene derivative is extremely useful as a synthetic intermediate for liquid crystals.

Claims

General formula (I)

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine A tetrahydronaphthalenone represented by the general formula (II):

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine 1-bromo-2-naphthol derivative represented by the general formula (II) and the general formula (III):

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine A method for producing a 2-naphthol derivative represented by the general formula (III) by producing a mixture of compounds represented by the formula (III):

The method according to claim ¹ , wherein at least one of X ¹ , X ² , X ³ and X ⁴ in the general formulas (I), (II) and (III) is a fluorine atom.

3. The method according to claim 1, wherein bromine, N-bromosuccinimide or 1,3-dibromo-5,5-dimethylhydantoin is used as the brominating agent.

3. The method according to claim 1, wherein bromine is used as the brominating agent.

5. The method according to claim 1, wherein hydrogen and a metal catalyst or metal are used as the reducing agent.

5. The method according to claim 1, wherein a sulfite is used as the reducing agent.

General formula (II)

(In the formula, X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, but at least one is a fluorine atom or a chlorine atom.) -Bromo-2-naphthol derivatives.

In the general formula ^(II), at least one is a fluorine atom, 1-bromo-2-naphthol derivative according to claim 7, wherein one of X ^1, X 2, ^{X 3} and ^{X 4.}

General formula (I)

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine Wherein a brominating agent is allowed to act on tetrahydronaphthalenone represented by the formula (II):

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine A 1-bromo-2-naphthol derivative represented by the formula:

In the general formula (I) and ^{^{(II), X 1, X}} 2, X 3 and where at least one of the ^{X 4} is a fluorine atom, a manufacturing method of 1-bromo-2-naphthol derivative according to claim 8 .

The method according to any one of claims 9 to 10, wherein bromine, N-bromosuccinimide or 1,3-dibromo-5,5-dimethylhydantoin is used as the brominating agent.

The method according to claim 9, wherein bromine is used as the brominating agent.

General formula (II)

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine A 1-bromo-2-naphthol derivative represented by the formula (III):

(Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X ¹ , X ² , X ³ and X ⁴ is fluorine A 2-naphthol derivative represented by an atom or a chlorine atom).

In formula (II) and ^{^{(III), X 1, X}} 2, X 3 and at least one of ^{X 4} where a fluorine atom, a manufacturing method of 2-naphthol derivative according to claim 13, wherein.

15. The production method according to claim 13, wherein hydrogen and a metal catalyst or metal are used as the reducing agent.

The method according to claim 13, wherein a sulfite is used as the reducing agent.