JP4238944B2 - Method for producing 4,6-diaminoresorcinol or a salt thereof - Google Patents

Description

【００１２】
（式中、Ｒはハロゲン原子、炭素原子数１〜５のアルキル基、ヒドロキシカルボニル基又は炭素原子数１〜５のアルコキシ基を表し、ｎは０又は１〜５のいずれかの整数を表し、２個以上のＲは互いに同一又は異なっていてもよい。）で表される４，６−ビス（置換）フェニルアゾレゾルシノールを金属触媒の存在下に水素還元し、４，６−ジアミノレゾルシノール又はその塩（その塩とは、４，６−ジアミノレゾルシノールの酸塩を意味する。以下、同じ）を得る方法において、溶媒として脂肪族ニトリル化合物を用いることを特徴とする４，６−ジアミノレゾルシノール又はその塩の製造方法に関する。
【００１３】
また、本発明は、上記の式〔１〕で表される４，６−ビス（置換）フェニルアゾレゾルシノールを金属触媒及び溶媒の存在下に水素還元し、４，６−ジアミノレゾルシノール又はその塩を得る還元方法において、溶媒として脂肪族ニトリル化合物、炭素数３〜５の脂肪族アルコール、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、ジエチレングリコールモノエチルエーテル及びジオキサンから選ばれる少なくとも一種の有機溶媒を用い、更に濾過助剤の存在下に還元を行うことを特徴とする４，６−ジアミノレゾルシノール又はその塩の製造方法に関する。
【００１４】
【発明の実施の形態】
本発明の出発原料である４，６−ビス（置換）フェニルアゾレゾルシノールは、式〔２〕
【００１５】
【化４】

【００１６】
（式中、Ｒとｎは式〔１〕中と同じに定義される。）
で表される（置換）アニリンをジアゾ化し（置換）ベンゼンジアゾニウム塩を得、該ジアゾニウム塩を、レゾルシノールとカップリング反応させて得ることができる。具体的には、置換アニリンと５〜１０重量倍の水との混合物中に、冷却下、アニリンに対して２．５〜４当量の無機酸を滴下し、この混合液中へ、（置換）アニリンに対し２〜３重量倍の水に溶解した１〜１．５倍モルの亜硝酸ナトリウム又は亜硝酸カリウムを１０℃以下で滴下することにより（置換）ベンゼンジアゾニウム塩を得る。無機酸としては塩酸、臭化水素酸、硫酸及び燐酸の中から選ばれた少なくとも１種の無機酸が用いられる。これらの無機酸の中で塩酸が工業上経済的に好ましい。
【００１７】
具体的には、例えばアニリン、２−クロロアニリン、４−クロロアニリン、２，６−ジクロロアニリン、ｏ−トルイジン、ｍ−トルイジン、ｐ−トルイジン、アントラニル酸、ｏ−アニシジン、ｍ−アニシジン及びｐ−アニシジン等を挙げることができ、これらのアニリンのいずれかを使用することが好ましい。経済性、化合物の安定性などでアニリンが最も好ましい。
【００１８】
（置換）ベンゼンジアゾニウム塩とレゾルシノールのカップリング反応は、公知の方法が用いられるが、本出願人が特開平９−１２４５７５号として出願した式〔３〕
【００１９】
【化５】

【００２０】
（式中、Ｒとｎは式〔１〕中と同じに定義され、ＸはＣｌ、Ｂｒ、ＯＳＯ₃Ｈ又はＯＰＯ₃Ｈ₂を表す。）
で表される（置換）ベンゼンジアゾニウム塩をアルカリ性にした溶媒中で反応させることによる方法、或いは特開平９−１５７２３９号として出願した、式〔３〕で表される（置換）ベンゼンジアゾニウム塩の溶液とアルカリ金属又はアルカリ土類金属の水酸化物の溶液又は懸濁液とを混合し、アルカリ性とした混合液を得、この混合液とレゾルシノール及び／又はそのアルカリ金属塩若しくはアルカリ土類金属塩を混合し反応させる方法が、好ましい。
【００２１】
この様に本願発明の原料である４，６−ビス（置換）フェニルアゾレゾルシノールはレゾルシノールとアルカリ性（置換）ベンゼンジアゾニュウム塩を反応したのち、酸性とした後濾集し、水洗したものである。これをそのまま用いても良いし、乾燥して用いても良い。還元反応の収率的に見れば水の混入は、濾液への４，６−ジアミノレゾルシノールの逃げを大きくするので、乾燥品が好ましい。反応混合物を精製しないで使用する為、４，６−ビス（置換）フェニルアゾレゾルシノールの純度は８０％前後であり、他に４−フェニルアゾレゾルシノールや２，４，６−トリフェニルアゾレゾルシノールや構造不明のものも含まれるが、大きな問題はない。この混合物をトルエンなどで再結晶し精製したものも、当然使用でき結果は良いが、４，６−ビスフェニルアゾレゾルシノールの精製は、その溶解性の悪さの為に非常に困難である。
【００２２】
次に、４，６−ビス（置換）フェニルアゾレゾルシノールの金属触媒及び溶媒の存在下の水素還元方法について述べる。還元反応に用いられる溶媒としては、、脂肪族ニトリル化合物、炭素数３〜５の脂肪族アルコール、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、ジエチレングリコールモノエチルエーテル及びジオキサンから選ばれる少なくとも一種の有機溶媒を用いられる。メタノール、エタノールでは、４，６−ジアミノレゾルシノールの濾液への逃げが多く、経済性に問題がある。ニトリル類以外は生成した４，６−ジアミノレゾルシノールの濾集の際に、極めて濾過性が悪く工業的操作は問題がある。その際に反応中に濾過助剤を加えると、濾過性は大幅に改善される。 一方、ニトリル類は濾過性も良く、濾液への逃げも少なく好ましい。濾過助剤の添加はニトリル類でも、濾過性改良に効果的である。
【００２３】
濾過助剤としては、活性炭、セライト、活性白土及びセルロースが用いられ、特には活性炭が好ましい。
【００２４】
濾過助剤の量としては４，６−ビス（置換）フェニルアゾレゾルシノールに対して１〜１００重量％であるが、濾過性が悪い場合は多く、良い場合は少なくて良い。好ましくは５〜３０重量％である。反応系への濾過助剤の添加は、濾過性の向上のみならず、反応時間の短縮にも効果的である。原料中の不純物を吸着し、触媒の劣化を防いでるのであろう。また、場合により、反応終了後に濾過助剤を添加しても濾過性の改善が見られる。
【００２５】
脂肪族ニトリル化合物としては、炭素数２〜６のモノシアノ化合物が好ましい。具体的には、アセトニトリル、プロピオニトリル、ブチロニトリル、イソブチロニトリル、バレロニトリル、イソバレロニトリル、トリメチルアセトニトリル、ヘキサンニトリル及び４−メチルバレロニトリル等が挙げられる。特に好ましいものは、反応が速く、経済的に安価なアセトニトリル、プロピオニトリル、ブチロニトリル及びイソブチロニトリル等が挙げられる。
【００２６】
更に、具体的に示せば、反応基質を４，６−ビスフェニルアゾレゾルシノールを用いた場合、４，６−ジアミノレゾルシノールの反応収率は９８〜９９％で、４，６−ジアミノレゾルシノールの結晶収率は９３〜９６％で得られ、更に、４，６−ジアミノレゾルシノールの粗結晶中のアニリン収率は、１〜２％となり、高純度の４，６−ジアミノレゾルシノールが高収率で結晶として単離することができる。一方、濾液には、ほぼ理論量のアニリンが含まれている。
【００２７】
溶媒の使用量は、４，６−ビス（置換）フェニルアゾレゾルシノールを基準として１〜５０重量倍、好ましくは２〜２０重量倍である。
【００２８】
本発明で使用する金属触媒としては、銅及び周期律表第８族元素の中から選ばれた少なくとも一種の金属である。周期律表第８族元素としては白金、パラジウム、ルテニウム、ロジウム、ニッケル、コバルト、イリジウム等が挙げられる。これらの金属触媒の中で白金及びパラジウムが、本反応では４，６−ジアミノレゾルシノールを高収率で得ることができ好ましい。
【００２９】
触媒の形態としては、例えばパラジウム黒や白金黒等の単体、ラネーニッケルやコバルト等の合金、塩化パラジウムや酢酸パラジウム等の金属塩、酸化銅や酸化白金等の金属酸化物、アセチルアセトン銅やアセチルアセトンパラジウム等の金属錯体及び炭素、シリカ、アルミナ、ジルコニア、チタニア、ゼオライト等の酸化物に担持させた担体付き金属等が挙げられる。これらの中で特には担体付き金属が回収再使用の都合上好ましく、パラジウム−炭素や白金−炭素が好ましい。特に白金−炭素が、低担持量にもかかわらず、パラジウム−活性炭より高活性で好ましい。
【００３０】
更に、活性を向上させる目的と反応及び酸処理等による劣化を抑制し、再使用を可能にする目的から、白金、パラジウムまたはルテニウム等の第一金属に、第二金属を添加した多元金属系触媒にすることもできる。第二金属としては、レニウム、イリジウム、錫、アンチモン、ゲルマニウム、インジウム及びロジウム等の一種以上を、第一金属に対して２〜５０原子モル％添加する事が好ましい。
【００３１】
具体的には、例えば５％Ｐｄ／１％Ｒｅ−Ｃ、５％Ｐｄ／２％Ｉｎ−Ｃ、２％Ｐｔ／０．５％Ｒｅ−Ｃ、１％Ｐｔ／０．２％Ｇｅ−Ｃ等を挙げることができる。
【００３２】
触媒の使用量は、４，６−ビス（置換）フェニルアゾレゾルシノールに対し金属分として０．０００５〜１０重量％が好ましく、特には０．００１〜１０重量％で使用される。
【００３３】
水素圧は、常圧〜１００００ｋＰａであるが、好ましくは常圧〜１０００ｋＰａである。反応温度は、−１０〜１５０℃で可能であるが、好ましくは０〜１００℃より好ましくは１０〜８０℃である。
【００３４】
反応液は、４，６−ジアミノレゾルシノールが固体となり存在している。取り出し方法について説明する。空気に触れないようにして、濾過することで４，６−ジアミノレゾルシノールを触媒、濾過助剤とともに得る事ができる。アニリンは濾液に行くが、濾過性が悪いとケーキの含液が多くアニリンの除去が不充分になるので、少量の反応溶媒、低級アルコール、水のいずれかで洗浄する。
【００３５】
４，６−ジアミノレゾルシノールはフリーでは、酸素、温度とも不安定であるので酸を加えて塩とする必要がある。酸としては塩酸、臭化水素酸、硫酸およびリン酸等が使用できるが塩酸がもっとも工業的に好ましい。２倍モル以上の塩酸水溶液に加えて、加熱溶解するか、ロート上に２倍モル以上の塩酸水溶液を加えて溶解または懸濁して抜き出し、加熱溶解する。不溶物を濾別し、必要によっては活性炭処理を行い、活性炭を濾別し塩酸を加えて冷却して析出した４，６−ジアミノレゾルシノール塩酸塩を濾集する。活性炭は脱色に卓効がある。
【００３６】
塩酸水溶液を用いて４，６−ジアミノレゾルシノールを溶解するとき、塩酸量は２〜10倍モル使用するが、塩酸が多いと溶解度が下がるので、４，６−ジアミノレゾルシノールの２〜３倍モルが好ましい。水は４，６−ジアミノレゾルシノールの１〜２０部使用するが、溶解度及び晶析の関係で３〜１０部が好ましい。活性炭は着色と目的に応じて必要量が変わるが、０〜１００重量％、好ましくは５〜３０重量％である。
【００３７】
活性炭処理後、濃塩酸を加えて塩析で固体を析出するが、加える塩酸は４，６−ジアミノレゾルシノールの４〜２０倍モルが良い。経済的には水量にも影響されるが、４〜８倍モルが好ましい。更に濾過後乾燥して４，６−ジアミノレゾルシノール２塩酸塩を得る。
【００３８】
４，６−ジアミノレゾルシノール２塩酸塩も酸化を受けやすいが、塩化第１錫を加えると酸化に対して抵抗効果がある。
尚、前記還元反応は、連続的に行う事が出来る。
【００３９】
【実施例】
以下、実施例により本願発明をより詳細に説明するが、本発明は、これらによって限定されるものではない。
参考例−１
アニリン４１ｇ、３５％塩酸９８ｇ、水１００ｇの混合溶液中に、０〜５℃で亜硝酸ナトリウム３０ｇを水５５ｇに溶解させた溶液を滴下し、塩化ベンゼンジアゾニウム水溶液を合成した。この塩化ベンゼンジアゾニウム水溶液を水酸化ナトリウム５５ｇ、水１１０ｇよりなる混合液に１０℃以下で滴下した。
【００４０】
この混合液をレゾルシノール２２ｇ、水酸化ナトリウム２４ｇ、水２２ｇよりなる混合液に１０℃で４０分かけ滴下した。滴下終了後１０℃で３時間撹拌した。反応終了後、反応混合物に塩酸を加え酸性とし、析出した固体を濾集、水洗、乾燥して６２ｇの暗赤色固体を得た。４，６−ビスフェニルアゾレゾルシノールの純度は７９．５％であり、約５％の２，４，６−トリフェニルアゾレゾルシノールを含む。
【００４１】
実施例１
４，６−ビスフェニルアゾレゾルシノール（純度７９．５％）１０．０ｇ（０．０２５ｍｏｌ）、アセトニトリル５０ｇ、５％Ｐｄ−Ｃ２．０ｇを１００ｍｌハステロイ製オートクレーブに仕込み、水素を３００ｋＰａの一定圧力で水素蓄圧器より供給しながら、攪拌速度６００ｒｐｍ、３０℃で反応させた。反応時間２．５時間で、水素蓄圧器の圧力減少が停止した。そこで攪拌停止後、オートクレーブを室温に戻してから、窒素置換後反応物を取り出した。スラリー状の反応物を窒素雰囲気下濾過によりケーキと濾液に分離した。この濾過時間は２０分であった。ケーキは、アセトニトリルで洗浄し、湿品を得た。湿品およびろ洗液（濾液と洗液を混合したもの）は塩酸塩として以下の分析を行った。
【００４２】
即ち、湿品及びろ洗液中に生成した４，６−ジアミノレゾルシノール（ＤＡＲ）とアニリンの収率を液体クロマトグラフィーで分析した。結果を表１に示す。湿品中のＤＡＲ収率は、９２．５％、ろ洗液中の収率は、４．５％で合計収率は９７％であった。アニリンの収率は、湿品中１．５％、ろ洗液中２２２．０％で合計収率は２２３．５％であった。
【００４３】
尚、アニリン収率が、２００％を越えるのは、原料の不純物として含まれる４−アゾレゾルシノール及び２，４，６−トリアゾレゾルシノールが水素化分解されてアニリンを遊離するためである。
【００４４】
比較例１
実施例１において溶媒をイソプロパノールに代えた他は実施例１と同様に還元反応を行った。濾過時間が、約１時間かかっても終わらないのでその後の処理を中断した。
【００４５】
実施例２
４，６−ビスフェニルアゾレゾルシノール（純度７９．５％）１０．０ｇ（０．０２５ｍｏｌ）、アセトニトリル５０ｇ、５％Ｐｄ−Ｃ２．０ｇ及び活性炭１．０ｇを１００ｍｌハステロイ製オートクレーブに仕込み、水素を３００ｋＰａの一定圧力で水素蓄圧器より供給しながら、攪拌速度６００ｒｐｍ、３０℃で反応させた。反応時間２．５時間で、水素蓄圧器の圧力減少が停止した。そこで攪拌停止後、オートクレーブを室温に戻してから、窒素置換後反応物を取り出した。スラリー状の反応物を窒素雰囲気下濾過によりケーキと濾液に分離した。この濾過時間は１０分であった。ケーキは、アセトニトリルで洗浄し、湿品を得た。実施例１と同様に分析を行った。湿品中のＤＡＲ収率は、９３．１％、濾洗液中の収率は、４．９％で合計収率は９８．０％であった。アニリンの収率は、結晶中１．５％、濾洗液中２２２．０％で、合計収率は２２３．５％であった。
【００４６】
実施例３〜１１、比較例２〜６
実施例２に於いて、アセトニトリルを他の溶媒に変えた他は、実施例２と同様に反応させた。結果を表１に示す。なお、濾過時間は、いずれも３０分以下であった。
【００４７】
【表１】

【００４８】
表１に示す様に還元反応溶媒として、アセトニトリル、プロピオニトリル及びブチロニトリルを用いることにより、結晶としてアニリン含量が少なく、ＤＡＲ収率が高い結果が得られた。メタノールやエタノールの場合は、濾液に溶解した４，６−ジアミノレゾルシノールが多く、結晶として得られた４，６−ジアミノレゾルシノールの収率が低い。
【００４９】
実施例１２
４，６−ビスフェニルアゾレゾルシノール（純度７９．１％）１６１ｇ（０．４ｍｏｌ）、アセトニトリル６３６ｇ、５％Ｐｄ−Ｃ５．０９ｇ及び活性炭（５０％含水品）３８．２ｇを２ｌＳＵＳ製オートクレーブに仕込み、水素を３ｋｇ／ｃｍ²の一定圧力で水素蓄圧器より供給しながら、攪拌速度４００ｒｐｍ、３０℃で反応させた。反応時間３時間で、水素蓄圧器の圧力減少が停止した。そこで攪拌停止後、オートクレーブを室温に戻してから、窒素置換後反応物を取り出しした。スラリー状の反応物を濾過によりケーキと濾液に分離した。ケーキは、アセトニトリル７７ｇと２３０ｇで２回洗浄した。湿品１５８．６ｇ、濾液７０４ｇと洗液を得た。
【００５０】
ケーキ中、濾液中および洗液中に生成した４，６−ジアミノレゾルシノール（ＤＡＲ）とアニリンを塩酸塩とした後、液体クロマトグラフィーで分析した結果、ケーキ中のＤＡＲ収率は、９３．８％、アニリン収率は３．４％であり、濾液中のＤＡＲ収率は、１．１％で、アニリン収率は、２０３．１％であった。更に、洗液中のＤＡＲ収率は、０．１％、アニリン収率６．５％であった。
【００５１】
次にこのケーキ６７．４ｇ（ＤＡＲ０．１６ｍｏｌ）を３５％塩酸水３４．４ｇ（２．２モル倍）、水１５３ｇ及び塩化第一スズ・２水和物０．６１ｇの溶液に加え６０℃で１時間で溶解させた。続いて濾過により触媒と活性炭を分離した。尚、この触媒と活性炭は、１％塩酸水１５．３ｇと３０．７ｇで２回洗浄した。
【００５２】
こうして得られた濾液に活性炭（５０％含水品）１３．４ｇを加え、８０℃で２時間攪拌した。
続いて、熱濾過により活性炭を分離した後、濾液に３５％塩酸水１１２ｇを加え、８０℃で２０分間加温後、１０℃まで冷却した。析出した結晶を濾別し２０％塩酸水９．２ｇで洗浄後５０℃で３時間減圧乾燥し、４，６−ジアミノレゾルシノール２塩酸塩２４．３ｇ（純度９９．３％）を得た。
【００５３】
実施例１３、１４
実施例１に於いて触媒を１％Ｐｔ−Ｃ１．０ｇ、２％Ｐｔ／０．５％Ｒｅ−Ｃに変えた以外は、同様に反応及び後処理操作を行い、それぞれ９．８３ｇ、９．６１ｇの結晶（湿品）を得た。
この結晶及び及び濾液の分析結果を表２に示す。
【００５４】
【表２】

【００５５】
【発明の効果】
反応溶媒として脂肪族ニトリル化合物を用いることにより、或いは、反応溶媒として脂肪族ニトリル化合物、炭素数３〜５の脂肪族アルコール、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、ジエチレングリコールモノエチルエーテル及びジオキサンから選ばれる少なくとも一種の有機溶媒を用い、更に濾過助剤の存在下に還元を行うことにより、高収率で４，６−ジアミノレゾルシノールが生成し、かつその４，６−ジアミノレゾルシノールの大部分が、スラリーとして分離するために濾過により高収率のまま捕集することができ、しかも副生するアニリン誘導体は、濾液として高回収率で分離することができる。こうして、反応直後に単離された４，６−ジアミノレゾルシノールの固体（粗結晶）は、アニリン誘導体含量が少なく、以降の精製を容易にし、且つ精製ロスを少なくすることができる。即ち、高純度の４，６−ジアミノレゾルシノールを高精製収率で容易に得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing 4,6-diaminoresorcinol or a salt thereof. More specifically, the present invention relates to a method for producing 4,6-diaminoresorcinol or a salt thereof by reduction of 4,6-bis (substituted) phenylazoresorcinol.
[0002]
4,6-Diaminoresorcinol is a monomer of polybenzoxazole, and this polybenzoxazole is a polymer having high strength, high elastic modulus, and excellent properties in heat resistance and chemical resistance (special table). (See Japanese Patent Application Laid-Open Nos. 61-501452 and 2-229143).
[0003]
[Prior art]
The reduction of 4,6-bisphenylazoresorcinol is usually reduced with hydrogen using a noble metal catalyst (Japanese Patent Laid-Open No. 7-242604). According to Japanese Patent Application Laid-Open No. 7-242604, the reduction is carried out in a solvent under neutral conditions. As the solvent, it is described that water, lower alcohol, aromatic hydrocarbons, halo-substituted benzenes, halogenated aliphatic hydrocarbons, ethers, and lower ketones are used alone or in combination. In addition, two methods are described for the post-treatment after completion of the reduction reaction. One is a method in which 4,6-diaminoresorcinol is obtained by filtration through celite as it is in a nitrogen atmosphere, and then an acid is added to form an acid salt. The catalyst and celite are separated by filtration and then purified and isolated. The second is a method in which an acid is added to the reaction solution to dissolve it as a salt, and the catalyst is filtered off and then purified and isolated.
[0004]
The former is effective in that the aniline produced in the reaction can be easily recovered and the purification process is simple, but the filterability is very poor. The loss of 4,6-diaminoresorcinol in the filtrate is large and the yield is as bad as 60%, which is not an industrial method.
[0005]
In the latter, acid is added to form a salt, so the stability in air is good and the operability is good. Moreover, filterability is also good and does not become a problem. However, there is a disadvantage that separation and purification of by-product aniline and 4,6-diaminoresorcinol are extremely complicated because they are in an acidic solution.
[0006]
[Problems to be solved by the invention]
In the reduction of 4,6-bis (substituted) phenylazoresorcinol, 2 equivalents of aniline derivative are by-produced in addition to 4,6-diaminoresorcinol. The most important problem of the method for reducing 4,6-bis (substituted) phenylazoresorcinol is how easily and easily this aniline derivative can be separated with little loss of the produced 4,6-diaminoresorcinol.
[0007]
As a result of intensive studies, the present inventors have found a method for industrially handling 4,6-diaminoresorcinol and have completed the present invention. That is, 4,6-diaminoresorcinol was obtained in high yield by reducing the 4,6-bisphenylazoresorcinol derivative with hydrogen in a selected solvent under a noble metal catalyst.
[0008]
However, filterability may be poor depending on the solvent. At that time, if a filter aid such as activated carbon is added and reacted, the filterability is remarkably improved.
[0009]
An object of the present invention is to provide a method capable of easily obtaining high-purity 4,6-diaminoresorcinol from 4,6-bis (substituted) phenylazoresorcinol in a high yield. This also improves the recovery rate of the aniline derivative, which is economically advantageous.
[0010]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found a method for solving the above-mentioned problems and have completed the present invention. That is, the present invention provides the formula [1]
[0011]
[Chemical 3]

[0012]
(In the formula, R represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, a hydroxycarbonyl group or an alkoxy group having 1 to 5 carbon atoms, n represents an integer of 0 or 1 to 5; Two or more Rs may be the same or different from each other.) 4,6-bis (substituted) phenylazoresorcinol represented by the following formula: 4,6-diaminoresorcinol or its 4,6-diaminoresorcinol characterized by using an aliphatic nitrile compound as a solvent in a method for obtaining a salt (the salt means an acid salt of 4,6-diaminoresorcinol; hereinafter the same) The present invention relates to a method for producing a salt.
[0013]
In the present invention, 4,6-bis (substituted) phenylazoresorcinol represented by the above formula [1] is hydrogen reduced in the presence of a metal catalyst and a solvent, and 4,6-diaminoresorcinol or a salt thereof is obtained. In the reduction method to be obtained, an aliphatic nitrile compound, an aliphatic alcohol having 3 to 5 carbon atoms, at least one organic solvent selected from ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether and dioxane is used as a solvent, Furthermore, it is related with the manufacturing method of 4, 6- diamino resorcinol or its salt characterized by performing reduction | restoration in presence of a filter aid.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The starting material of the present invention, 4,6-bis (substituted) phenylazoresorcinol has the formula [2]
[0015]
[Formula 4]

[0016]
(In the formula, R and n are defined as in formula [1].)
The (substituted) aniline represented by formula (2) can be diazotized to obtain a (substituted) benzenediazonium salt, and the diazonium salt can be obtained by a coupling reaction with resorcinol. Specifically, 2.5 to 4 equivalents of an inorganic acid is added dropwise to a mixture of a substituted aniline and 5 to 10 times by weight of water while cooling, and (substitute) A (substituted) benzenediazonium salt is obtained by dropping 1 to 1.5 times moles of sodium nitrite or potassium nitrite dissolved in 2 to 3 times by weight of water with respect to aniline at 10 ° C. or lower. As the inorganic acid, at least one inorganic acid selected from hydrochloric acid, hydrobromic acid, sulfuric acid and phosphoric acid is used. Of these inorganic acids, hydrochloric acid is industrially preferred.
[0017]
Specifically, for example, aniline, 2-chloroaniline, 4-chloroaniline, 2,6-dichloroaniline, o-toluidine, m-toluidine, p-toluidine, anthranilic acid, o-anisidine, m-anisidine and p- Anisidine and the like can be mentioned, and it is preferable to use any of these anilines. Aniline is most preferable in view of economy and stability of the compound.
[0018]
For the coupling reaction of (substituted) benzenediazonium salt and resorcinol, a known method is used, but the formula [3] filed by the present applicant as Japanese Patent Application Laid-Open No. 9-124575.
[0019]
[Chemical formula 5]

[0020]
(In the formula, R and n are defined as in formula [1], and X represents Cl, Br, OSO ₃ H or OPO ₃ H _2. )
Or a solution of a (substituted) benzenediazonium salt represented by the formula [3] filed as JP-A-9-157239, or a method by reacting the (substituted) benzenediazonium salt represented by And an alkali metal or alkaline earth metal hydroxide solution or suspension are mixed to obtain an alkaline mixture, and this mixture and resorcinol and / or its alkali metal salt or alkaline earth metal salt are mixed. A method of mixing and reacting is preferable.
[0021]
As described above, 4,6-bis (substituted) phenylazoresorcinol, which is a raw material of the present invention, is obtained by reacting resorcinol with an alkaline (substituted) benzenediazonium salt, acidifying the solution, and then collecting and washing with water. . This may be used as it is, or may be used after drying. From the viewpoint of the yield of the reduction reaction, mixing of water increases the escape of 4,6-diaminoresorcinol into the filtrate, so a dry product is preferred. Since the reaction mixture is used without purification, the purity of 4,6-bis (substituted) phenylazoresorcinol is around 80%. Besides, 4-phenylazoresorcinol, 2,4,6-triphenylazoresorcinol and the structure Some are unknown, but there are no major problems. A product obtained by recrystallizing and purifying this mixture with toluene or the like can of course be used and has good results. However, purification of 4,6-bisphenylazoresorcinol is very difficult due to its poor solubility.
[0022]
Next, a hydrogen reduction method in the presence of a metal catalyst of 4,6-bis (substituted) phenylazoresorcinol and a solvent will be described. The solvent used for the reduction reaction is at least one organic solvent selected from aliphatic nitrile compounds, aliphatic alcohols having 3 to 5 carbon atoms, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether and dioxane. Is used. In methanol and ethanol, there are many escapes of 4,6-diaminoresorcinol to the filtrate, and there is a problem in economical efficiency. Except for nitriles, when the produced 4,6-diaminoresorcinol is collected by filtration, the filterability is very poor and industrial operation is problematic. At this time, if a filter aid is added during the reaction, the filterability is greatly improved. On the other hand, nitriles are preferable because they have good filterability and little escape to the filtrate. Addition of a filter aid is effective for improving filterability even with nitriles.
[0023]
As the filter aid, activated carbon, celite, activated clay, and cellulose are used, and activated carbon is particularly preferable.
[0024]
The amount of the filter aid is 1 to 100% by weight based on 4,6-bis (substituted) phenylazoresorcinol, but it is often when filterability is poor and may be small when good. Preferably, it is 5 to 30% by weight. Addition of a filter aid to the reaction system is effective not only for improving filterability but also for shortening the reaction time. It will adsorb impurities in the raw material and prevent the catalyst from deteriorating. In some cases, the filterability is improved even when a filter aid is added after the reaction is completed.
[0025]
As the aliphatic nitrile compound, a monocyano compound having 2 to 6 carbon atoms is preferable. Specific examples include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, trimethylacetonitrile, hexanenitrile, 4-methylvaleronitrile and the like. Particularly preferred are acetonitrile, propionitrile, butyronitrile, isobutyronitrile, etc., which have a fast reaction and are economically inexpensive.
[0026]
More specifically, when 4,6-bisphenylazoresorcinol is used as the reaction substrate, the reaction yield of 4,6-diaminoresorcinol is 98-99%, and the crystal yield of 4,6-diaminoresorcinol is The yield is 93 to 96%, and the yield of aniline in the crude crystals of 4,6-diaminoresorcinol is 1 to 2%, and high-purity 4,6-diaminoresorcinol is obtained as crystals in a high yield. It can be isolated. On the other hand, the filtrate contains an approximately theoretical amount of aniline.
[0027]
The amount of the solvent used is 1 to 50 times by weight, preferably 2 to 20 times by weight, based on 4,6-bis (substituted) phenylazoresorcinol.
[0028]
The metal catalyst used in the present invention is at least one metal selected from copper and Group 8 elements of the periodic table. Examples of Group 8 elements of the Periodic Table include platinum, palladium, ruthenium, rhodium, nickel, cobalt, iridium and the like. Among these metal catalysts, platinum and palladium are preferable because 4,6-diaminoresorcinol can be obtained in a high yield in this reaction.
[0029]
Examples of catalyst forms include simple substances such as palladium black and platinum black, alloys such as Raney nickel and cobalt, metal salts such as palladium chloride and palladium acetate, metal oxides such as copper oxide and platinum oxide, acetylacetone copper and acetylacetone palladium, etc. And metal with a carrier supported on oxides such as carbon, silica, alumina, zirconia, titania and zeolite. Among these, a metal with a carrier is particularly preferred for the convenience of recovery and reuse, and palladium-carbon and platinum-carbon are preferred. In particular, platinum-carbon is preferred because it is more active than palladium-activated carbon, despite the low loading.
[0030]
Furthermore, for the purpose of improving the activity and suppressing the deterioration due to the reaction and acid treatment, etc., and the purpose of enabling reuse, a multi-metallic catalyst in which a second metal is added to a first metal such as platinum, palladium or ruthenium. It can also be. As the second metal, it is preferable to add 2 to 50 atomic mol% of rhenium, iridium, tin, antimony, germanium, indium, rhodium and the like with respect to the first metal.
[0031]
Specifically, for example, 5% Pd / 1% Re-C, 5% Pd / 2% In-C, 2% Pt / 0.5% Re-C, 1% Pt / 0.2% Ge-C, etc. Can be mentioned.
[0032]
The amount of the catalyst used is preferably from 0.0005 to 10% by weight, particularly from 0.001 to 10% by weight, based on 4,6-bis (substituted) phenylazoresorcinol.
[0033]
The hydrogen pressure is from normal pressure to 10000 kPa, preferably from normal pressure to 1000 kPa. The reaction temperature can be −10 to 150 ° C., preferably 0 to 100 ° C., more preferably 10 to 80 ° C.
[0034]
In the reaction solution, 4,6-diaminoresorcinol is present as a solid. The extraction method will be described. By filtering without contact with air, 4,6-diaminoresorcinol can be obtained together with the catalyst and the filter aid. The aniline goes to the filtrate, but if the filterability is poor, the cake will contain a lot of liquid and the removal of aniline will be insufficient, so wash with a small amount of reaction solvent, lower alcohol, or water.
[0035]
Since 4,6-diaminoresorcinol is free and unstable in both oxygen and temperature, it is necessary to add an acid to form a salt. As the acid, hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid and the like can be used, but hydrochloric acid is most preferred industrially. Add to a 2 times mole or more hydrochloric acid aqueous solution and dissolve by heating, or add 2 times a mole or more hydrochloric acid aqueous solution on a funnel to dissolve or suspend and take out and dissolve by heating. Insoluble matters are filtered off, and if necessary, activated carbon treatment is performed. The activated carbon is filtered off, and hydrochloric acid is added thereto, followed by cooling to precipitate 4,6-diaminoresorcinol hydrochloride. Activated carbon has an excellent effect on decolorization.
[0036]
When 4,6-diaminoresorcinol is dissolved using an aqueous hydrochloric acid solution, the amount of hydrochloric acid is 2 to 10 times mol. However, since the solubility decreases when there is much hydrochloric acid, 2 to 3 times mol of 4,6-diaminoresorcinol is used. preferable. Water is used in an amount of 1 to 20 parts of 4,6-diaminoresorcinol, but 3 to 10 parts is preferable in terms of solubility and crystallization. The required amount of activated carbon varies depending on the color and purpose, but is 0 to 100% by weight, preferably 5 to 30% by weight.
[0037]
After the activated carbon treatment, concentrated hydrochloric acid is added to precipitate a solid by salting out, and the added hydrochloric acid is preferably 4 to 20 times mol of 4,6-diaminoresorcinol. Economically, it is also influenced by the amount of water, but 4 to 8 times mol is preferable. Further, after filtration, drying is performed to obtain 4,6-diaminoresorcinol dihydrochloride.
[0038]
4,6-Diaminoresorcinol dihydrochloride is also susceptible to oxidation, but adding stannous chloride has a resistance to oxidation.
The reduction reaction can be performed continuously.
[0039]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited by these.
Reference Example-1
A solution prepared by dissolving 30 g of sodium nitrite in 55 g of water at 0 to 5 ° C. was dropped into a mixed solution of 41 g of aniline, 98 g of 35% hydrochloric acid and 100 g of water to synthesize a benzenediazonium chloride aqueous solution. This aqueous solution of benzenediazonium chloride was added dropwise to a mixed solution consisting of 55 g of sodium hydroxide and 110 g of water at 10 ° C. or lower.
[0040]
This mixed solution was dropped into a mixed solution composed of 22 g of resorcinol, 24 g of sodium hydroxide and 22 g of water at 10 ° C. over 40 minutes. After completion of dropping, the mixture was stirred at 10 ° C. for 3 hours. After completion of the reaction, the reaction mixture was acidified with hydrochloric acid, and the precipitated solid was collected by filtration, washed with water and dried to obtain 62 g of a dark red solid. The purity of 4,6-bisphenylazoresorcinol is 79.5% and contains about 5% 2,4,6-triphenylazoresorcinol.
[0041]
Example 1
10.0 g (0.025 mol) of 4,6-bisphenylazoresorcinol (purity: 79.5%), 50 g of acetonitrile, and 2.0 g of 5% Pd-C were charged into a 100 ml Hastelloy autoclave, and hydrogen was supplied at a constant pressure of 300 kPa. While supplying from the pressure accumulator, the reaction was carried out at a stirring speed of 600 rpm and 30 ° C. The pressure reduction of the hydrogen accumulator stopped after a reaction time of 2.5 hours. Therefore, after the stirring was stopped, the autoclave was returned to room temperature, and then the reactant was taken out after nitrogen substitution. The slurry-like reaction product was separated into a cake and a filtrate by filtration under a nitrogen atmosphere. This filtration time was 20 minutes. The cake was washed with acetonitrile to obtain a wet product. The wet product and the filter washing liquid (mixed filtrate and washing liquid) were analyzed as the hydrochloride salt as follows.
[0042]
That is, the yields of 4,6-diaminoresorcinol (DAR) and aniline produced in the wet product and the filtrate were analyzed by liquid chromatography. The results are shown in Table 1. The DAR yield in the wet product was 92.5%, the yield in the filtrate was 4.5%, and the total yield was 97%. The yield of aniline was 1.5% in the wet product and 222.0% in the filter washing solution, and the total yield was 223.5%.
[0043]
The reason why the aniline yield exceeds 200% is that 4-azoresorcinol and 2,4,6-triazoresorcinol contained as raw material impurities are hydrocracked to release aniline.
[0044]
Comparative Example 1
The reduction reaction was performed in the same manner as in Example 1 except that the solvent was changed to isopropanol in Example 1. Even if the filtration time took about 1 hour, the subsequent treatment was interrupted.
[0045]
Example 2
10.0 g (0.025 mol) of 4,6-bisphenylazoresorcinol (purity 79.5%), 50 g of acetonitrile, 2.0 g of 5% Pd—C and 1.0 g of activated carbon were charged into a 100 ml Hastelloy autoclave, and hydrogen was supplied at 300 kPa. The reaction was carried out at a stirring speed of 600 rpm and 30 ° C. while being supplied from a hydrogen pressure accumulator at a constant pressure of. The pressure reduction of the hydrogen accumulator stopped after a reaction time of 2.5 hours. Therefore, after the stirring was stopped, the autoclave was returned to room temperature, and then the reactant was taken out after nitrogen substitution. The slurry-like reaction product was separated into a cake and a filtrate by filtration under a nitrogen atmosphere. This filtration time was 10 minutes. The cake was washed with acetonitrile to obtain a wet product. Analysis was performed in the same manner as in Example 1. The DAR yield in the wet product was 93.1%, the yield in the filtrate was 4.9%, and the total yield was 98.0%. The yield of aniline was 1.5% in the crystal and 222.0% in the filter washing solution, and the total yield was 223.5%.
[0046]
Examples 3-11, Comparative Examples 2-6
In Example 2, the reaction was carried out in the same manner as in Example 2 except that acetonitrile was changed to another solvent. The results are shown in Table 1. The filtration time was 30 minutes or less in all cases.
[0047]
[Table 1]

[0048]
As shown in Table 1, by using acetonitrile, propionitrile and butyronitrile as the reduction reaction solvent, the result was that the aniline content was small as crystals and the DAR yield was high. In the case of methanol or ethanol, the amount of 4,6-diaminoresorcinol dissolved in the filtrate is large, and the yield of 4,6-diaminoresorcinol obtained as crystals is low.
[0049]
Example 12
161 g (0.4 mol) of 4,6-bisphenylazoresorcinol (purity: 79.1%), 636 g of acetonitrile, 5.09 g of 5% Pd-C, and 38.2 g of activated carbon (50% water-containing product) were charged in a 2 lSUS autoclave. While supplying hydrogen from a hydrogen pressure accumulator at a constant pressure of 3 kg / cm ² , the reaction was performed at a stirring speed of 400 rpm and 30 ° C. In the reaction time of 3 hours, the pressure reduction of the hydrogen pressure accumulator stopped. Therefore, after the stirring was stopped, the autoclave was returned to room temperature, and then the reactant was taken out after nitrogen substitution. The slurry-like reaction product was separated into a cake and a filtrate by filtration. The cake was washed twice with 77 g and 230 g of acetonitrile. A wet product of 158.6 g and a filtrate of 704 g were obtained.
[0050]
The 4,6-diaminoresorcinol (DAR) and aniline produced in the cake, filtrate and washing solution were converted to hydrochloride and analyzed by liquid chromatography. As a result, the DAR yield in the cake was 93.8%. The aniline yield was 3.4%, the DAR yield in the filtrate was 1.1%, and the aniline yield was 203.1%. Furthermore, the DAR yield in the washing solution was 0.1%, and the aniline yield was 6.5%.
[0051]
Next, 67.4 g of this cake (DAR 0.16 mol) was added to a solution of 35% aqueous hydrochloric acid 34.4 g (2.2 mol times), water 153 g and stannous chloride dihydrate 0.61 g at 60 ° C. It was dissolved in 1 hour. Subsequently, the catalyst and activated carbon were separated by filtration. The catalyst and activated carbon were washed twice with 15.3 g and 30.7 g of 1% aqueous hydrochloric acid.
[0052]
13.4 g of activated carbon (50% water-containing product) was added to the filtrate thus obtained, and the mixture was stirred at 80 ° C. for 2 hours.
Subsequently, activated carbon was separated by hot filtration, 112 g of 35% hydrochloric acid was added to the filtrate, and the mixture was heated at 80 ° C. for 20 minutes and then cooled to 10 ° C. The precipitated crystals were separated by filtration, washed with 9.2 g of 20% aqueous hydrochloric acid and dried under reduced pressure at 50 ° C. for 3 hours to obtain 24.3 g (purity 99.3%) of 4,6-diaminoresorcinol dihydrochloride.
[0053]
Examples 13 and 14
Except that the catalyst was changed to 1% Pt—C 1.0 g and 2% Pt / 0.5% Re—C in Example 1, the reaction and post-treatment operations were performed in the same manner, and 9.83 g and 9. 61 g of crystals (wet product) were obtained.
Table 2 shows the analysis results of the crystals and the filtrate.
[0054]
[Table 2]

[0055]
【The invention's effect】
By using an aliphatic nitrile compound as a reaction solvent, or from an aliphatic nitrile compound, an aliphatic alcohol having 3 to 5 carbon atoms, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether and dioxane as a reaction solvent. By performing reduction in the presence of a filter aid using at least one organic solvent selected, 4,6-diaminoresorcinol is produced in a high yield, and most of the 4,6-diaminoresorcinol is produced. In order to separate it as a slurry, it can be collected in a high yield by filtration, and the aniline derivative produced as a by-product can be separated as a filtrate with a high recovery rate. Thus, the solid (crude crystal) of 4,6-diaminoresorcinol isolated immediately after the reaction has a low aniline derivative content, facilitates subsequent purification, and reduces purification loss. That is, high-purity 4,6-diaminoresorcinol can be easily obtained with a high purification yield.

Claims (5)

Formula [1]

(In the formula, R represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, a hydroxycarbonyl group or an alkoxy group having 1 to 5 carbon atoms, n represents an integer of 0 or 1 to 5; And two or more Rs may be the same or different from each other.) 4,6-bis (substituted) phenylazoresorcinol represented by the following formula: 4,6-diaminoresorcinol Or a reduction method for obtaining a salt thereof, using at least one metal selected from copper and Group 8 elements of the periodic table as a metal catalyst, an aliphatic nitrile compound, an aliphatic alcohol having 3 to 5 carbon atoms as a solvent, At least selected from ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether and dioxane Using the seeds of organic solvents, further active carbon, Celite, and performing at least one reduced in the presence of a filter aid selected from activated clay and cellulose, the production of 4,6-diaminoresorcinol or a salt thereof Method. Aliphatic nitrile compound according to claim 1 is a monocyano hydrocarbon compound having 2 to 6 carbon atoms, 4,6-diaminoresorcinol or a salt thereof. Metal catalyst is a platinum in claim 1, 4,6-diaminoresorcinol or a salt thereof. Metal catalyst according to claim 1, platinum, ruthenium or palladium, a multi-element catalyst added rhenium, indium, tin, antimony, germanium, one or more elements selected from iridium and rhodium, 4,6 A method for producing diaminoresorcinol or a salt thereof. The amount of filter aid is 1-100% by weight relative to 4,6-bis (substituted) phenyl azo resorcinol method according to claim 1 4,6-diaminoresorcinol or a salt thereof according.