JP3629957B2

JP3629957B2 - Method for producing cyclohexanedimethanol

Info

Publication number: JP3629957B2
Application number: JP17990698A
Authority: JP
Inventors: 博伊藤; 泰一郎岩村; 安久吉田; 幹郎中澤
Original assignee: New Japan Chemical Co Ltd
Current assignee: New Japan Chemical Co Ltd
Priority date: 1998-06-26
Filing date: 1998-06-26
Publication date: 2005-03-16
Anticipated expiration: 2018-06-26
Also published as: JP2000007595A

Description

【０００１】
【発明の属する技術分野】
本発明は、シクロヘキサンジメタノール（以下「ＣＨＤＭ」と略記する。）の製造方法に関し、より詳しくは、アルデヒド含有量の少ないＣＨＤＭの製造方法に関する。ＣＨＤＭは、ポリエステル樹脂、ポリウレタン樹脂及びポリカーボネート樹脂等のジオール成分として適用することにより、これらの樹脂の耐熱性、透明性、耐候性及び成型性の向上等に有効である。特にポリエチレンテレフタレ−トの改質に有用な化合物として注目されている。
【０００２】
【従来の技術】
ＣＨＤＭの製造方法としては、シクロヘキサンジカルボン酸ジアルキルのエステル基を銅系触媒の存在下、還元してＣＨＤＭを含む反応粗物を得、次いで当該反応粗物を減圧蒸留する方法が知られている。当該還元反応に効果的な銅系触媒としては、銅クロマイト、銅酸化物／亜鉛酸化物、銅酸化物／チタン酸化物、銅酸化物／鉄酸化物、更にこれらの助触媒としてバリウム、マグネシウム及び亜鉛の酸化物で変性したうえで還元活性化した触媒等が挙げられる（米国特許第３３３４１４９号、特開平６−１９２１４６号、特開平７−１９６５４９号、米国特許第５３３４７７９号、米国特許第５０３０７７１号）。
【０００３】
又、一般に、１級飽和アルコールを銅の存在下、高温に加熱すると脱水素反応が起き、アルデヒドが生成することが知られている（ＪＯＨＮＡ．ＭＯＮＩＣＫ，「ＡＬＣＯＨＯＬＳ」，ｐ４４，ＲＥＩＮＨＯＬＤＢＯＯＫＣＯＲＰＯＲＡＴＩＯＮ（１９６８））。
【０００４】
本発明者等の検討によれば、銅系触媒を使用してシクロヘキサンジカルボン酸ジアルキルを還元して得られる反応粗物中には銅（金属又はイオン）が含まれており、反応粗物の減圧蒸留中に蒸留液温が高くなると、不純物として混在する銅がＣＨＤＭのヒドロキシメチル基の脱水素反応触媒として働き、ホルミルシクロヘキサンメタノール（以下「アルデヒド化合物」と略記する。）が副生し、蒸留したＣＨＤＭ中に混入してくる。かかるアルデヒド化合物を含むＣＨＤＭをジオール成分として前記樹脂を製造した場合、目的とする重合度が得られなかったり、樹脂が着色したり、更には臭気の面で問題となる。
【０００５】
【発明が解決しようとする課題】
本発明は、銅系触媒の存在下、シクロヘキサンジカルボン酸ジアルキルのエステル基を還元して得られるＣＨＤＭを含む反応粗物を減圧蒸留して精製するに際し、アルデヒド化合物を殆ど含まない高品質のＣＨＤＭの製造方法を提供することを目的とする。
【０００６】
【課題を解決するための手段】
本発明者らは、上記課題を解決すべく鋭意検討した結果、シクロヘキサンジカルボン酸ジアルキルのエステル基を還元して得られる反応粗物を減圧蒸留して精製されたＣＨＤＭを製造するに際し、蒸留中の缶液に含まれる銅含有量を特定濃度以下に保持することにより、アルデヒド化合物の含有量が極めて微量のＣＨＤＭを得ることが出来ることを見いだし、かかる知見に基づいて本発明を完成するに至った。
【０００７】
即ち、本発明に係るＣＨＤＭの製造方法は、一般式（１）

［式中、Ｒは炭素数１〜４の直鎖状又は分岐鎖状のアルキル基を表す。］で表されるシクロヘキサンジカルボン酸ジアルキルを銅系触媒の存在下、還元して得られる一般式（２）

で表されるシクロヘキサンジメタノールを含む反応粗物を減圧下で蒸留するに際し、蒸留中の缶液に含まれる銅の含有量を蒸留の開始時から終了時まで５ｐｐｍ以下に保つことを特徴とする。
【０００８】
【発明の実施の形態】
本発明に係るＣＨＤＭとしては、１，２−ＣＨＤＭ、１，３−ＣＨＤＭ及び１，４−ＣＨＤＭが例示される。
【０００９】
これらのＣＨＤＭは、例えば、銅系触媒の存在下、１，２−シクロヘキサンジカルボン酸ジアルキル、１，３−シクロヘキサンジカルボン酸ジアルキル及び１，４−シクロヘキサンジカルボン酸ジアルキルなど、それぞれ対応する置換位置のエステル基を有するシクロヘキサンジカルボン酸ジアルキルを還元して得られる化合物である。
【００１０】
これらのジエステルを構成するアルキル基は、炭素数が１〜４であって、脂肪族一価アルコールに由来するものである。
【００１１】
シクロヘキサンジカルボン酸ジアルキルとして、具体的には、１，４−シクロヘキサンジカルボン酸ジメチル、１，４−シクロヘキサンジカルボン酸ジエチル、１，４−シクロヘキサンジカルボン酸ジイソプロピル、１，４−シクロヘキサンジカルボン酸ジイソブチル、１，３−シクロヘキサンジカルボン酸ジメチル、１，３−シクロヘキサンジカルボン酸ジエチル、１，３−シクロヘキサンジカルボン酸ジイソプロピル、１，３−シクロヘキサンジカルボン酸ジイソブチル、１，２−シクロヘキサンジカルボン酸ジメチル、１，２−シクロヘキサンジカルボン酸ジエチル、１，２−シクロヘキサンジカルボン酸ジイソプロピル、１，２−シクロヘキサンジカルボン酸ジイソブチル等が例示される。
【００１２】
還元反応で使用される銅系触媒としては、エステル還元能を有する公知の銅含有触媒が使用でき、具体的には、銅酸化物／クロム酸化物、銅酸化物／亜鉛酸化物、銅酸化物／チタン酸化物、銅酸化物／鉄酸化物、更にこれらの助触媒としてバリウム、マンガン、アルミ、亜鉛又はマグネシウ等の酸化物を含有する触媒が例示される。
【００１３】
以上の銅系触媒のうち、いわゆるアドキンス型の市販されている銅酸化物／クロム酸化物成型触媒や銅酸化物／亜鉛酸化物成型触媒及びこれらに酸化バリウムや酸化マンガン等の助触媒を含む成型触媒が特に好ましい。
【００１４】
固定床用銅系成型触媒は、反応に使用する前に予備還元処理が一般に好ましい。予備還元処理は、水素／窒素混合ガス流通下、常圧又は加圧下にて、１５０〜３００℃の温度範囲内で水素濃度を徐々に、上昇させながら実施する一般的な方法が採用できる。
【００１５】
シクロヘキサンジカルボン酸ジアルキルの還元反応の圧力としては、１８５〜３００ｋｇ／ｃｍ^２、温度は２００〜２８０℃の範囲が好適である。
【００１６】
本発明に係る固定床還元反応の形態としては、前記銅系成型触媒を充填した固定床反応装置の上部から水素ガスと原料を供給し、生成物と過剰の水素を反応器下部から抜き出す流下法、又は下部から水素ガスと原料を供給し、生成物と過剰の水素を反応器上部から抜き出す上昇法のいずれでも可能である。
【００１７】
かくして得られる反応粗物を減圧蒸留して精製されたＣＨＤＭを得るに際し、減圧蒸留中の缶液に含まれる銅含有量は５ｐｐｍ以下である。５ｐｐｍを越える条件下で蒸留精製した場合には、アルデヒド化合物の量が増加し、本発明所定の効果を得ることができない。
【００１８】
又、本発明において、減圧蒸留前の反応粗物に含まれる銅を吸着剤を用いて予め除去することは、蒸留精製中に副生するアルデヒド化合物の量を低減する上で効果的な工業的処理方法である。特に上記吸着処理を適用して当該銅含有量を１ｐｐｍ以下に低減することにより、副生するアルデヒド化合物の量を極めて少量とすることができる。
【００１９】
かかる銅の吸着剤としては、活性炭、多孔性無機化合物及びカチオン交換体よりなる群から選ばれる１種又は２種以上の吸着性物質が推奨される。以上の吸着性物質の中でも活性炭が効果、価格の面で工業的に最も好ましい。
【００２０】
活性炭としては、一般に工業的に入手できるものが使用できる。木材、木炭、ヤシガラ、石炭のいずれを原料にしたものでも良く、水蒸気賦活炭でも塩化亜鉛賦活炭のいずれでも使用できるが、好ましくは水蒸気賦活炭が使用される。形状は粉末炭、粒状炭のいずれでも使用できるが、前者は処理原料である反応粗物と混合して吸着濾過する回分法を採用し、後者は反応粗物を粒状活性炭の固定層に通過させて吸着処理する連続法を採用出来る。処理温度は反応粗物の融点以上であって、２００℃以下の範囲が好ましい。
【００２１】
多孔性無機化合物としては、天然ゼオライト、合成ゼオライト、活性白土、シリカゲル、活性アルミナ、ハイドロタルサイト等が挙げられる。形状は、粉末、粒状のいずれでも使用できるが、前者は処理原料である反応粗物と混合して吸着濾過する回分法を採用し、後者は反応粗物を粒状活性炭の固定層に通過させて吸着処理する連続法を採用出来る。処理温度は反応粗物の融点以上あって、２００℃以下の範囲が好ましい。
【００２２】
カチオン交換体としては、例えばカチオン交換樹脂や無機系カチオン交換体が挙げられる。
【００２３】
カチオン交換樹脂としては、樹脂母体にスルホン酸基、カルボン酸基等のカチオン交換基を有する樹脂が例示される。樹脂母体としては、一般にはスチレン樹脂、スチレン系共重合系樹脂、フッ素化エチレン樹脂、フェノール樹脂、アクリル酸系樹脂等が用いられる。吸着方法としては、カラムに充填した球状のカチオン交換樹脂層に反応粗物を通過させ吸着処理する連続法が採用出来る。一方、処理温度は原料の融点以上であって、１００℃以下の範囲が好ましい。１００℃を越えると樹脂の耐熱性の限界を越えるので問題である。
【００２４】
無機系カチオン交換体としては、ジルコニウム系、スズ系、アンチモン系、チタン系及びビスマス系のものが例示される。形状は、粉末、粒状のいずれでも使用できるが、前者は処理原料である反応粗物と混合して吸着濾過する回分法を採用し、後者は反応粗物を粒状活性炭の固定層に通過させて吸着処理する連続法を採用出来る。処理温度は反応粗物の融点以上あって、２００℃以下の範囲が好ましい。
【００２５】
処理方法が連続方式のときは、吸着剤の種類に拘わらず、粒状吸着剤を充填したカラム内に反応粗物をカラム上方から下方に通過させる流下方式、又はカラム下方から上方に通過させる上昇方式のいずれの方式をも採用出来る。
【００２６】
通液速度（ＬＨＳＶ）は、処理条件及び吸着剤の種類によって異なるが、０．５〜２０ｈ^−１の範囲が好ましい。０．５ｈ^−１未満では生産性が低く、２０ｈ^−１を越える場合には、その処理効果が低くなり、いずれも好ましくない。
【００２７】
一方、処理方法が回分方式のときは、その処理条件は、吸着剤の種類によって異なってくるが、一般的には次のような条件が例示出来る。即ち、吸着剤の添加量は０．１〜１０重量％の範囲であり、より好ましくは０．３〜５重量％の範囲である。０．１重量％未満ではその効果は小さく、１０重量％を越えて適用しても大きな添加効果が認められない。
【００２８】
処理時間としては、一般に０．１〜１０時間の範囲が好ましい。０．１時間未満ではその処理効果が低く、１０時間を越える場合には生産性が低くなりいずれも好ましくない。
【００２９】
更に、反応粗物を溶媒に溶解して溶液として処理することも可能である。溶媒の種類は、特に限定されず、原料のＣＨＤＭを溶解するものであって、且つＣＨＤＭに不活性なものであれば良い。特に、アルコール類が好んで用いられる。
【００３０】
当該アルコール類としては、メタノール、エタノール、ｎ−プロパノール、イソプロパノール、ｎ−ブタノール、イソブタノール、ｎ−ヘキサノール、シクロヘキサノール、ｎ−オクタノール、２−エチルヘキサノール等が例示される。特に、工業的にメタノールが推奨される。
【００３１】
溶媒の使用量は、適宜選択され、系中のＣＨＤＭの濃度が１０重量％以上、好ましくは３０重量％以上となるように調整される。１０重量％未満では生産性が悪く問題となる。
【００３２】
尚、吸着剤の種類に拘わらず、反応粗物の着色及び空気酸化を防止するために、いずれも窒素雰囲気下で行うことが好ましい。
【００３３】
反応粗物を減圧蒸留精製するに際し、水素化ナトリウムホウ素（以下「ＳＢＨ」と略記する。）、次亜リン酸ナトリウム又は次亜リン酸ナトリウムの水和物を添加して減圧蒸留することにより、アルデヒド化合物の副生を更に低減出来る。特に吸着処理を併用した場合、その効果は顕著である。本発明で用いるＳＢＨ及び次亜リン酸ナトリウムは、共に工業的に入手可能なものであり、特に後者は一水和物が一般的である。
【００３４】
その添加量は、減圧蒸留中に脱水素して発生してくるアルデヒド化合物を還元し、元のＣＨＤＭに還元出来る量以上であれば十分であり、具体的には反応粗物に対して０．０１〜５重量％の範囲が好ましい。０．０１重量％未満ではその添加効果は少なく、５重量％を越えて用いた場合では製品高となり、且つ減圧蒸留ピッチ中の無機物の含有量が大きくなり蒸留釜からの排出が困難となる。
【００３５】
使用形態は粉末のまま、又は水溶液として添加使用出来る。
【００３６】
一方、処理温度は、前記反応粗物の減圧蒸留条件であれば十分その還元作用の発現が可能である。
【００３７】
粗物の減圧蒸留は、回分蒸留でも連続蒸留のいずれでも可能である。いずれの蒸留方式であっても、減圧蒸留中の缶液の推奨される温度は１３０〜２５０℃であり、特に１５０〜２３０℃が好ましい。１３０℃未満では、たとえ高真空であってもＣＨＤＭの留出は困難であり、一方、２５０℃を越えると脱水素反応が顕著となり好ましくない。
【００３８】
減圧蒸留装置塔頂の減圧度としては、３０ｍｍＨｇ以下、好ましくは１５ｍｍＨｇ以下が良い。減圧度が３０ｍｍＨｇを越えると缶液温が高くなり、前記の不都合な脱水素反応が顕著となる。
【００３９】
【実施例】
以下に製造例及び実施例を掲げて本発明を具体的に説明する。
【００４０】
サンプル組成
ガスクロマトグラフィーによって分析した。分析条件はガラス製２ｍカラムを用い、充填剤として１５％ＤＥＧＳ／Ｃｈｒｏｍｏｓｏｒｂを使用し、カラム温度１８０℃、キャリアーガスとして窒素を６０ｍｌ／ｍｉｎの流量にて行った。
【００４１】
銅の含有量
原子吸光分析法によって分析した。
【００４２】
アルデヒド化合物の含有量
ジニトロフェニルヒドラジン比色法によって分析した。
【００４３】
製造例１
容量０．３１４Ｌの固定床反応装置にマンガンを含む円筒状（直径３．５ｍｍ×高さ３．５ｍｍ）の銅−クロム酸化物成型触媒（酸化銅４０重量％、酸化クロム４５重量％、酸化マンガン２．１重量％）４９９ｇを充填し、水素／窒素混合ガスにて加熱下に予備還元処理を行った。予備活性化処理後、純度９５．４％の１，３−シクロヘキサンジカルボン酸ジメチルを３２０ｍｌ／ｈ（ＬＨＳＶ＝１．０２ｈ^−１）の送液速度で２５０℃、１８０ｋｇ／ｃｍ^２Ｇの条件下、反応塔の上部から水素ガス７．４Ｎｍ^３／ｈと共に供給してエステル基の還元反応を連続的に行った。この固定床連続還元反応によって塔下部から得られた反応粗物の分析結果を以下に示す。
１，３−ＣＨＤＭ純度９２．２％
アルデヒド含有量０．０ｐｐｍ
銅含有量４．２ｐｐｍ
【００４４】
製造例２
反応圧力を２００ｋｇ／ｃｍ^２Ｇとした以外は、製造例１と同様の条件で還元反応を連続的に行った。この固定床連続還元反応によって得られた反応粗物の分析結果を以下に示す。
１，３−ＣＨＤＭ純度９６．３％
アルデヒド化合物含有量０．０ｐｐｍ
銅含有量０．４６ｐｐｍ
【００４５】
製造例３
製造例１で使用した装置に円筒状（直径３．５ｍｍ×高さ３．５ｍｍ）の銅−亜鉛−アルミニウム酸化物成型触媒（酸化銅４２重量％、酸化亜鉛重量４４％、酸化アルミニウム３重量％）４８７ｇを充填し、水素／窒素混合ガスにて加熱下に予備還元処理を行った。予備活性化処理後、純度９６．２％の１，４−シクロヘキサンジカルボン酸ジメチルを３２０ｍｌ／ｈ（ＬＨＳＶ／Ｖ＝１．０２ｈ^−１）の送液速度で２５０℃、１８０ｋｇ／ｃｍ^２Ｇの条件下、反応塔の上部から水素ガス７．４Ｎｍ^３／ｈと共に供給してエステル基の還元反応を連続的に行った。この固定床連続還元反応によって塔下部から得られた反応粗物の分析結果を以下に示す。
１，４−ＣＨＤＭ純度９３．３％
アルデヒド化合物含有量０．０ｐｐｍ
銅含有量３．８ｐｐｍ
【００４６】
実施例１
製造例１で得られた反応粗物（１，３−ＣＨＤＭ純度：９２．２％、銅含有量：４．２ｐｐｍ）を１００℃に保ちながら、吸着剤として粒状活性炭（商品名：粒状白鷺ＫＬ、武田薬品工業社製、水蒸気賦活、以下「粒状活性炭Ａ」という。）１５０ｍｌを充填した内径１５ｍｍ、長さ１．０ｍのガラス製カラムに下降流で空間速度（ＬＨＳＶ）５ｈ^−１（供給速度＝７５０ｍＬ／ｈ）にて通液して銅の吸着処理を行った。次いで、吸着処理して得た反応粗物１ｋｇを２５ｃｍのウィドマー精留塔を備えた２Ｌ蒸留フラスコに仕込み、初留２０重量％（対反応粗物）を留去した後、１６０〜１７５℃／１０〜１５ｍｍＨｇ（缶液温：１８０〜２２５℃）の条件下で減圧蒸留を実施して主留７０重量％（対反応粗物）を留出後、フラスコにピッチとして１０重量％（対反応粗物）残して減圧蒸留を終了した。当該反応粗物の吸着処理結果及び減圧蒸留の結果を第１表に示す。
【００４７】
実施例２
吸着剤として、粒状活性炭（商品名：顆粒炭ＳＧＳ、二村化学工業社製、塩化亜鉛賦活、以下「粒状活性炭Ｂ」という。）を使用した他は実施例１と同様にして減圧蒸留した。当該反応粗物の吸着処理結果及び減圧蒸留の結果を第１表に示す。
【００４８】
実施例３
吸着剤として、合成ゼオライト（商品名：ゼオラムＡ−３、東ソー社製、柱状品、３ｍｍΦ）を使用した他は実施例１と同様にして減圧蒸留した。当該反応粗物の吸着処理結果及び減圧蒸留の結果を第１表に示す。
【００４９】
実施例４
吸着剤として、カチオン交換樹脂（商品名：ダイアイオンＰＫ２０８、三菱化学社製、球状品、ポーラス型、ポリスチレン系スルホン基型）を使用した他は実施例１と同様にして減圧蒸留した。当該反応粗物の吸着処理結果及び減圧蒸留の結果を第１表に示す。
【００５０】
比較例１
製造例１で得られた反応粗物の吸着剤処理を行わなかった以外は実施例１と同様に減圧蒸留を行った。当該反応粗物の減圧蒸留結果を表１に示す。
【００５１】

【００５２】
実施例５
製造例２で得られた反応粗物（１，３−ＣＨＤＭ純度：９６．３％、銅含有量：０．４６ｐｐｍ）を吸着処理しなかった以外は実施例１と同様に減圧蒸留を行ったところ、蒸留後の缶液に含まれる銅含有量は４．８ｐｐｍであり、主留分中のアルデヒド化合物量は３５ｐｐｍであった。
【００５３】
実施例６
製造例３で得られた反応粗物（１，４−ＣＨＤＭ純度９３．３％、銅含有量３．８ｐｐｍ）を１００℃に保ちながら、「粒状活性炭Ａ」を１５０ｍｌ充填したガラス製カラムに下降流で空間速度（ＬＨＳＶ）４ｈ^−１（供給速度＝６００ｍＬ／ｈ）にて通液して，銅の吸着処理を行った後、減圧蒸留原料とした。次いで、吸着処理して得た反応粗物１ｋｇを２５ｃｍのウィドマー精留塔を備えた２Ｌ蒸留フラスコに仕込み、初留２０重量％（対反応粗物）を留去した後、１６０〜１７５℃／１０〜１５ｍｍＨｇ（缶液温：１８０〜２２０℃）の条件下で減圧蒸留を実施して主留７０重量％（対反応粗物）を留出後、フラスコにピッチとして１０重量％（対反応粗物）残して減圧蒸留を終了した。当該反応粗物の吸着処理結果及び減圧蒸留の結果を第２表に示す。
【００５４】
実施例７
吸着剤として、合成ゼオライト（商品名：ゼオラムＡ−３）を使用した他は実施例６と同様にして減圧蒸留した。当該反応粗物の吸着処理結果及び減圧蒸留の結果を第２表に示す。
【００５５】
実施例８
吸着剤として、カチオン交換樹脂（商品名：ダイアイオンＰＫ２０８）を使用した他は実施例６と同様にして減圧蒸留した。当該反応粗物の吸着処理結果及び減圧蒸留の結果を第２表に示す。
【００５６】
比較例２
製造例３で得られた反応粗物（銅含有量：３．８ppm）の吸着剤処理を行わなかった以外は実施例６と同様に減圧蒸留を行った。当該反応粗物の減圧蒸留結果を表２に示す。
【００５７】

【００５８】
実施例９
製造例３で得られた反応粗物（１，４−ＣＨＤＭ純度：９３．３％、銅含有量：３．８ｐｐｍ）を実施例６と同様に「粒状活性炭Ａ］で吸着処理した後、得られた反応粗物（吸着処理液中の銅含有量：０．３１ｐｐｍ）に還元剤としてＳＢＨを０．２重量％（対反応粗物）を添加した以外は実施例６と同様の減圧蒸留を行ったところ、蒸留後の缶液に含まれる銅含有量は２．９ｐｐｍであり、主留分中のアルデヒド化合物量は２．２ｐｐｍであった。
【００５９】
実施例１０
反応粗物（吸着処理液中の銅含有量：０．３１ｐｐｍ）に還元剤としてＳＢＨに代えて次亜リン酸ナトリウム一水和物（ＮａＨ_２ＰＯ_２・Ｈ_２Ｏ）０．５重量％（対反応粗物）を添加した以外は実施例９と同様にして減圧蒸留を行ったところ、蒸留後の缶液に含まれる銅含有量は２．８ｐｐｍであり、主留分中のアルデヒド化合物量は２．５ｐｐｍであった。
【００６０】
実施例１１
製造例３で得られた反応粗物（銅含有量３．８ｐｐｍ）１２ｋｇを原料とし、「粒状活性炭Ａ」１．５Ｌを充填した大型ガラス製カラム（内径４０ｍｍ、長さ１．５ｍ）を用い、当該反応粗物を１００℃に保ちながら空間速度４ｈ^−１（供給速度＝６Ｌ／ｈ）にてカラム下降流にて通液して，銅の吸着処理を行った。この吸着処理した反応粗物（銅含有量０．３９ｐｐｍ）を回分蒸留装置（２０Ｌ容量）にて、沸点範囲が１７０℃／１５ｍｍＨｇ（液温〜１９０℃）になるまでの初留分２０％を留出させて１，４−ＣＨＤＭ純度９６．８％のトッピング品（銅含有量０．４９ｐｐｍ）９．２ｋｇを得た。
【００６１】
更に、当該トッピング品９ｋｇを原料として連続蒸留装置にて減圧蒸留を行った。即ち、精留用の規則性充填物（ＳＵＳ３１６）を充填した理論段数１０段の連続蒸留塔に前記トッピング品を１Ｌ／ｈの速度で連続供給し、還流状態が定常になってから、還流比（Ｒ／Ｄ）＝２、減圧度１５ｍｍＨｇ、留出温度１７０℃、缶液温度１８５℃に設定し、塔頂から主留分を約０．９Ｌ／ｈ、塔底から高沸点物分を約０．１Ｌ／ｈの速度で連続的に抜き出しつつ行った。５時間減圧蒸留（最終缶液中の銅含有量：３．８ｐｐｍ）を実施して、主留分（１，４−ＣＨＤＭ純度：９９．７％）を約４．５ｋｇ、高沸点物分を約０．５ｋｇ得た。主留分中のアルデヒド含有量は３５ｐｐｍであった。
【００６２】
【発明の効果】
本発明に係る条件を適用することにより、不純アルデヒドの副生が極めて小さい高品質のＣＨＤＭを工業的に製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing cyclohexanedimethanol (hereinafter abbreviated as “CHDM”), and more particularly to a method for producing CHDM having a low aldehyde content. By applying CHDM as a diol component such as a polyester resin, a polyurethane resin, and a polycarbonate resin, CHDM is effective in improving the heat resistance, transparency, weather resistance, and moldability of these resins. In particular, it has attracted attention as a compound useful for the modification of polyethylene terephthalate.
[0002]
[Prior art]
As a method for producing CHDM, a method is known in which a reaction crude product containing CHDM is obtained by reducing an ester group of a dialkylcyclohexanedicarboxylate in the presence of a copper catalyst, and then the reaction crude product is distilled under reduced pressure. Examples of copper catalysts effective for the reduction reaction include copper chromite, copper oxide / zinc oxide, copper oxide / titanium oxide, copper oxide / iron oxide, and barium, magnesium and co-catalysts thereof. Examples include catalysts that have been modified with zinc oxide and then activated by reduction (US Pat. No. 3,334,149, JP-A-6-192146, JP-A-7-196549, US Pat. No. 5,334,795, US Pat. No. 5,030,771). ).
[0003]
In general, it is known that when a primary saturated alcohol is heated to a high temperature in the presence of copper, a dehydrogenation reaction occurs and an aldehyde is formed (JOHN A. MONICK, “ALCOHOLS”, p44, REINHOLD BOOKCORPORATION (1968). )).
[0004]
According to the study by the present inventors, the reaction crude obtained by reducing the dialkyl cyclohexanedicarboxylate using a copper catalyst contains copper (metal or ion), and the reaction crude is reduced in pressure. When the temperature of the distillate increases during distillation, copper mixed as impurities acts as a catalyst for dehydrogenation of the hydroxymethyl group of CHDM, and formylcyclohexanemethanol (hereinafter abbreviated as “aldehyde compound”) is by-produced and distilled. It gets mixed in CHDM. When the resin is produced using CHDM containing such an aldehyde compound as a diol component, the desired degree of polymerization cannot be obtained, the resin is colored, and there is a problem in terms of odor.
[0005]
[Problems to be solved by the invention]
In the present invention, when a reaction crude product containing CHDM obtained by reducing an ester group of a dialkylcyclohexanedicarboxylate in the presence of a copper catalyst is purified by distillation under reduced pressure, high-quality CHDM containing almost no aldehyde compound is purified. An object is to provide a manufacturing method.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have produced a CHDM purified by distillation under reduced pressure of the reaction crude product obtained by reducing the ester group of the dialkylcyclohexanedicarboxylate. By keeping the copper content contained in the can liquid below a specific concentration, it was found that an extremely small amount of CHDM can be obtained, and the present invention has been completed based on such knowledge. .
[0007]
That is, the process for producing CHDM according to the present invention comprises the general formula (1)

[Wherein, R represents a linear or branched alkyl group having 1 to 4 carbon atoms. The general formula (2) obtained by reducing a dialkylcyclohexanedicarboxylate represented by formula (2) in the presence of a copper catalyst.

When the reaction crude product containing cyclohexanedimethanol represented by the formula is distilled under reduced pressure, the copper content contained in the can during the distillation is kept at 5 ppm or less from the start to the end of the distillation. .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the CHDM according to the present invention include 1,2-CHDM, 1,3-CHDM, and 1,4-CHDM.
[0009]
These CHDMs are, for example, ester groups at corresponding substitution positions such as dialkyl 1,2-cyclohexanedicarboxylate, dialkyl 1,3-cyclohexanedicarboxylate and dialkyl 1,4-cyclohexanedicarboxylate in the presence of a copper-based catalyst. It is a compound obtained by reducing dialkyl cyclohexanedicarboxylate having
[0010]
The alkyl group constituting these diesters has 1 to 4 carbon atoms and is derived from an aliphatic monohydric alcohol.
[0011]
Specific examples of the dialkyl cyclohexanedicarboxylate include dimethyl 1,4-cyclohexanedicarboxylate, diethyl 1,4-cyclohexanedicarboxylate, diisopropyl 1,4-cyclohexanedicarboxylate, diisobutyl 1,4-cyclohexanedicarboxylate, 1,3 -Dimethyl cyclohexanedicarboxylate, diethyl 1,3-cyclohexanedicarboxylate, diisopropyl 1,3-cyclohexanedicarboxylate, diisobutyl 1,3-cyclohexanedicarboxylate, dimethyl 1,2-cyclohexanedicarboxylate, diethyl 1,2-cyclohexanedicarboxylate 1,2-cyclohexanedicarboxylate diisopropyl, 1,2-cyclohexanedicarboxylate diisobutyl and the like.
[0012]
As the copper-based catalyst used in the reduction reaction, a known copper-containing catalyst having ester reducing ability can be used. Specifically, copper oxide / chromium oxide, copper oxide / zinc oxide, copper oxide / Titanium oxides, copper oxides / iron oxides, and catalysts containing barium, manganese, aluminum, zinc, magnesium or other oxides as examples of these promoters.
[0013]
Of the above copper-based catalysts, so-called Adkins-type commercially available copper oxide / chromium oxide molding catalysts and copper oxide / zinc oxide molding catalysts, and moldings containing cocatalysts such as barium oxide and manganese oxide. A catalyst is particularly preferred.
[0014]
The copper-based molded catalyst for fixed bed is generally preferably subjected to a pre-reduction treatment before being used for the reaction. The pre-reduction treatment can be performed by a general method in which the hydrogen concentration is gradually increased within a temperature range of 150 to 300 ° C. under a hydrogen / nitrogen mixed gas flow, at normal pressure or under pressure.
[0015]
The pressure for the reduction reaction of the dialkyl cyclohexanedicarboxylate is preferably 185 to 300 kg / cm ² and the temperature is in the range of 200 to 280 ° C.
[0016]
As a form of the fixed bed reduction reaction according to the present invention, a flow-down method in which hydrogen gas and raw material are supplied from the upper part of the fixed bed reactor filled with the copper-based molded catalyst, and the product and excess hydrogen are extracted from the lower part of the reactor. Alternatively, any ascending method in which hydrogen gas and raw materials are supplied from the lower portion and the product and excess hydrogen are extracted from the upper portion of the reactor is possible.
[0017]
When the crude reaction product thus obtained is distilled under reduced pressure to obtain purified CHDM, the copper content contained in the can during vacuum distillation is 5 ppm or less. When purified by distillation under conditions exceeding 5 ppm, the amount of the aldehyde compound increases, and the predetermined effect of the present invention cannot be obtained.
[0018]
Further, in the present invention, removing copper contained in the reaction crude before distillation under reduced pressure in advance using an adsorbent is an effective industrial method for reducing the amount of aldehyde compounds by-produced during distillation purification. It is a processing method. In particular, by applying the adsorption treatment to reduce the copper content to 1 ppm or less, the amount of by-product aldehyde compound can be made extremely small.
[0019]
As the copper adsorbent, one or more adsorbents selected from the group consisting of activated carbon, porous inorganic compounds and cation exchangers are recommended. Among the above adsorptive substances, activated carbon is industrially most preferable in terms of effect and price.
[0020]
As the activated carbon, those generally available industrially can be used. Any of wood, charcoal, coconut husk, and coal may be used as raw materials. Either steam activated charcoal or zinc chloride activated charcoal can be used, but steam activated charcoal is preferably used. Either powdered coal or granular charcoal can be used, but the former employs a batch method in which it is mixed with the reaction raw material, which is the raw material, and adsorbed and filtered, while the latter allows the reaction crude to pass through a fixed bed of granular activated carbon. It is possible to adopt a continuous method of adsorption treatment. The treatment temperature is preferably not less than the melting point of the reaction crude product and not more than 200 ° C.
[0021]
Examples of the porous inorganic compound include natural zeolite, synthetic zeolite, activated clay, silica gel, activated alumina, hydrotalcite and the like. The shape can be either powder or granular, but the former employs a batch method in which it is mixed with the reaction crude that is the raw material for processing and adsorbed and filtered, and the latter passes the reaction crude through a fixed bed of granular activated carbon. A continuous method for adsorption treatment can be adopted. The treatment temperature is preferably in the range of 200 ° C. or less, which is higher than the melting point of the reaction crude.
[0022]
Examples of the cation exchanger include cation exchange resins and inorganic cation exchangers.
[0023]
Examples of the cation exchange resin include resins having a cation exchange group such as a sulfonic acid group and a carboxylic acid group in the resin matrix. As the resin matrix, styrene resin, styrene copolymer resin, fluorinated ethylene resin, phenol resin, acrylic acid resin and the like are generally used. As the adsorption method, a continuous method in which a reaction crude product is allowed to pass through a spherical cation exchange resin layer packed in a column can be employed. On the other hand, the processing temperature is preferably not less than the melting point of the raw material and not more than 100 ° C. If the temperature exceeds 100 ° C., the heat resistance limit of the resin is exceeded, which is a problem.
[0024]
Examples of inorganic cation exchangers include zirconium, tin, antimony, titanium and bismuth. The shape can be either powder or granular, but the former employs a batch method in which it is mixed with the reaction crude that is the raw material for processing and adsorbed and filtered, and the latter passes the reaction crude through a fixed bed of granular activated carbon. A continuous method for adsorption treatment can be adopted. The treatment temperature is preferably in the range of 200 ° C. or less, which is higher than the melting point of the reaction crude.
[0025]
When the treatment method is a continuous method, regardless of the type of adsorbent, a flow-down method in which the reaction crude is passed from the top to the bottom of the column packed with the granular adsorbent, or a lift method in which the column is passed from the bottom to the top. Any of these methods can be adopted.
[0026]
The liquid flow rate (LHSV) varies depending on the treatment conditions and the type of adsorbent, but is preferably in the range of 0.5 to 20 h ⁻¹ . Low productivity is less than 0.5h ^-1, if exceeding ^{20h -1,} the treatment effect is low, both undesirable.
[0027]
On the other hand, when the treatment method is a batch system, the treatment conditions vary depending on the type of adsorbent, but the following conditions can be generally exemplified. That is, the amount of adsorbent added is in the range of 0.1 to 10% by weight, more preferably in the range of 0.3 to 5% by weight. If the amount is less than 0.1% by weight, the effect is small, and even if the amount exceeds 10% by weight, a large addition effect is not recognized.
[0028]
In general, the treatment time is preferably in the range of 0.1 to 10 hours. If it is less than 0.1 hour, the treatment effect is low, and if it exceeds 10 hours, the productivity is low, which is not preferable.
[0029]
Further, the reaction crude product can be dissolved in a solvent and treated as a solution. The type of the solvent is not particularly limited as long as it dissolves the raw material CHDM and is inert to CHDM. In particular, alcohols are preferably used.
[0030]
Examples of the alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-hexanol, cyclohexanol, n-octanol, 2-ethylhexanol and the like. In particular, methanol is recommended industrially.
[0031]
The amount of the solvent used is appropriately selected and adjusted so that the concentration of CHDM in the system is 10% by weight or more, preferably 30% by weight or more. If it is less than 10% by weight, the productivity is poor and becomes a problem.
[0032]
Regardless of the type of adsorbent, it is preferable to carry out both in a nitrogen atmosphere in order to prevent coloring of the reaction crude and air oxidation.
[0033]
When the reaction crude product is purified by distillation under reduced pressure, sodium borohydride (hereinafter abbreviated as “SBH”), sodium hypophosphite or sodium hypophosphite hydrate is added and distilled under reduced pressure, Byproduct of aldehyde compound can be further reduced. In particular, when the adsorption treatment is used in combination, the effect is remarkable. Both SBH and sodium hypophosphite used in the present invention are industrially available, and the latter is generally a monohydrate.
[0034]
The amount added is sufficient if it is more than the amount that can reduce the aldehyde compound generated by dehydrogenation during vacuum distillation and reduce it to the original CHDM. A range of 01 to 5% by weight is preferred. If the amount is less than 0.01% by weight, the effect of addition is small, and if it exceeds 5% by weight, the product becomes high, and the content of inorganic substances in the vacuum distillation pitch increases, making it difficult to discharge from the distillation kettle.
[0035]
The usage form can be added as a powder or as an aqueous solution.
[0036]
On the other hand, if the treatment temperature is under the reduced-pressure distillation conditions of the reaction crude product, the reduction action can be sufficiently exhibited.
[0037]
The crude product can be distilled under reduced pressure by either batch distillation or continuous distillation. Regardless of the distillation method, the recommended temperature of the can during the vacuum distillation is 130 to 250 ° C, and particularly preferably 150 to 230 ° C. If it is less than 130 ° C., it is difficult to distill CHDM even under high vacuum.
[0038]
The degree of vacuum at the top of the vacuum distillation apparatus tower is 30 mmHg or less, preferably 15 mmHg or less. When the degree of vacuum exceeds 30 mmHg, the temperature of the can liquid becomes high, and the above-described inconvenient dehydrogenation reaction becomes remarkable.
[0039]
【Example】
Hereinafter, the present invention will be specifically described with reference to production examples and examples.
[0040]
Sample composition Analyzed by gas chromatography. The analysis conditions were a glass 2 m column, 15% DEGS / Chromosorb was used as a filler, column temperature was 180 ° C., and nitrogen was used as a carrier gas at a flow rate of 60 ml / min.
[0041]
Copper content Analyzed by atomic absorption spectrometry.
[0042]
Aldehyde compound content Dinitrophenylhydrazine was analyzed by a colorimetric method.
[0043]
Production Example 1
Cylindrical (diameter 3.5 mm x height 3.5 mm) copper-chromium oxide molding catalyst (40 wt% copper oxide, 45 wt% chromium oxide, manganese oxide) containing manganese in a fixed bed reactor with a capacity of 0.314L 2.1 wt%) 499 g was charged, and a preliminary reduction treatment was performed under heating with a hydrogen / nitrogen mixed gas. After the preactivation treatment, dimethyl 1,3-cyclohexanedicarboxylate having a purity of 95.4% was supplied at a liquid feed rate of 320 ml / h (LHSV = 1.02 h ⁻¹ ) at 250 ° C. and 180 kg / cm ² G. The reduction reaction of the ester group was continuously carried out by supplying hydrogen gas 7.4 Nm ³ / h from the upper part of the reaction tower. The analysis results of the reaction crude obtained from the bottom of the tower by this fixed bed continuous reduction reaction are shown below.
1,3-CHDM purity 92.2%
Aldehyde content 0.0ppm
Copper content 4.2ppm
[0044]
Production Example 2
The reduction reaction was continuously performed under the same conditions as in Production Example 1 except that the reaction pressure was 200 kg / cm ² G. The analysis result of the reaction crude obtained by this fixed bed continuous reduction reaction is shown below.
1,3-CHDM purity 96.3%
Aldehyde compound content 0.0 ppm
Copper content 0.46ppm
[0045]
Production Example 3
Cylindrical (diameter 3.5 mm x height 3.5 mm) copper-zinc-aluminum oxide molding catalyst (42% by weight of copper oxide, 44% by weight of zinc oxide, 3% by weight of aluminum oxide) in the apparatus used in Production Example 1 487 g was charged, and a preliminary reduction treatment was performed with heating in a hydrogen / nitrogen mixed gas. After the preactivation treatment, dimethyl 1,4-cyclohexanedicarboxylate having a purity of 96.2% was supplied at a liquid feed rate of 320 ml / h (LHSV / V = 1.02 h ⁻¹ ) at 250 ° C. and 180 kg / cm ² G. Below, hydrogen gas 7.4 Nm ³ / h was supplied from the upper part of the reaction tower to continuously reduce the ester group. The analysis results of the reaction crude obtained from the bottom of the tower by this fixed bed continuous reduction reaction are shown below.
1,4-CHDM purity 93.3%
Aldehyde compound content 0.0ppm
Copper content 3.8ppm
[0046]
Example 1
While maintaining the reaction crude product (1,3-CHDM purity: 92.2%, copper content: 4.2 ppm) obtained in Production Example 1 at 100 ° C., granular activated carbon (trade name: granular white birch KL) is used as an adsorbent. , Manufactured by Takeda Pharmaceutical Co., Ltd., steam activated, hereinafter referred to as “granular activated carbon A”.) Space velocity (LHSV) 5h ⁻¹ (feed rate) in a glass column having an inner diameter of 15 mm and a length of 1.0 m packed with 150 ml. = 750 mL / h), and copper adsorption treatment was performed. Next, 1 kg of the reaction crude obtained by the adsorption treatment was charged into a 2 L distillation flask equipped with a 25 cm Widmer rectification column, and after distillation of 20% by weight (vs. reaction crude), 160 to 175 ° C. / After distillation under reduced pressure under conditions of 10 to 15 mmHg (can solution temperature: 180 to 225 ° C.) to distill 70% by weight of main fraction (vs. reaction crude), 10% by weight (vs. reaction crude) as a pitch in the flask. Product) Distillation under reduced pressure was completed. The results of adsorption treatment of the reaction crude and the results of vacuum distillation are shown in Table 1.
[0047]
Example 2
Distillation under reduced pressure was performed in the same manner as in Example 1 except that granular activated carbon (trade name: Granular Charcoal SGS, manufactured by Nimura Chemical Co., Ltd., zinc chloride activated, hereinafter referred to as “granular activated carbon B”) was used as the adsorbent. The results of adsorption treatment of the reaction crude and the results of vacuum distillation are shown in Table 1.
[0048]
Example 3
Distillation under reduced pressure was performed in the same manner as in Example 1 except that synthetic zeolite (trade name: Zeolum A-3, manufactured by Tosoh Corporation, columnar product, 3 mmΦ) was used as the adsorbent. The results of adsorption treatment of the reaction crude and the results of vacuum distillation are shown in Table 1.
[0049]
Example 4
Distillation under reduced pressure was carried out in the same manner as in Example 1 except that a cation exchange resin (trade name: Diaion PK208, manufactured by Mitsubishi Chemical Corporation, spherical product, porous type, polystyrene sulfone group type) was used as the adsorbent. The results of adsorption treatment of the reaction crude and the results of vacuum distillation are shown in Table 1.
[0050]
Comparative Example 1
Distillation under reduced pressure was performed in the same manner as in Example 1 except that the reaction crude product obtained in Production Example 1 was not subjected to the adsorbent treatment. Table 1 shows the results of distillation under reduced pressure of the reaction crude product.
[0051]

[0052]
Example 5
Distillation under reduced pressure was performed in the same manner as in Example 1 except that the reaction crude product obtained in Production Example 2 (1,3-CHDM purity: 96.3%, copper content: 0.46 ppm) was not subjected to adsorption treatment. However, the copper content contained in the can after distillation was 4.8 ppm, and the amount of aldehyde compound in the main fraction was 35 ppm.
[0053]
Example 6
While maintaining the reaction crude product (1,4-CHDM purity 93.3%, copper content 3.8 ppm) obtained in Production Example 3 at 100 ° C., it descends to a glass column packed with 150 ml of “granular activated carbon A”. The solution was passed through at a space velocity (LHSV) of 4 h ⁻¹ (feed rate = 600 mL / h) and subjected to copper adsorption treatment, and then used as a vacuum distillation raw material. Next, 1 kg of the reaction crude obtained by the adsorption treatment was charged into a 2 L distillation flask equipped with a 25 cm Widmer rectification column, and after distillation of 20% by weight (vs. reaction crude), 160 to 175 ° C. / Distillation under reduced pressure was carried out under conditions of 10 to 15 mmHg (can temperature: 180 to 220 ° C.) to distill 70% by weight of the main fraction (vs. reaction crude), and then 10% by weight (vs. reaction crude) as a pitch in the flask. Product) Distillation under reduced pressure was completed. The results of adsorption treatment of the reaction crude and the results of vacuum distillation are shown in Table 2.
[0054]
Example 7
Distillation under reduced pressure was performed in the same manner as in Example 6 except that synthetic zeolite (trade name: Zeolum A-3) was used as the adsorbent. The results of adsorption treatment of the reaction crude and the results of vacuum distillation are shown in Table 2.
[0055]
Example 8
Distillation under reduced pressure was performed in the same manner as in Example 6 except that a cation exchange resin (trade name: Diaion PK208) was used as the adsorbent. The results of adsorption treatment of the reaction crude and the results of vacuum distillation are shown in Table 2.
[0056]
Comparative Example 2
Distillation under reduced pressure was performed in the same manner as in Example 6 except that the reaction crude product obtained in Production Example 3 (copper content: 3.8 ppm) was not subjected to the adsorbent treatment. The results of vacuum distillation of the reaction crude are shown in Table 2.
[0057]

[0058]
Example 9
The reaction crude product obtained in Production Example 3 (1,4-CHDM purity: 93.3%, copper content: 3.8 ppm) was adsorbed with “granular activated carbon A” in the same manner as in Example 6 and then obtained. Distillation under reduced pressure was performed in the same manner as in Example 6 except that 0.2% by weight of SBH (as a reaction crude product) was added as a reducing agent to the obtained reaction crude product (copper content in the adsorption treatment solution: 0.31 ppm). As a result, the copper content contained in the can after distillation was 2.9 ppm, and the amount of the aldehyde compound in the main fraction was 2.2 ppm.
[0059]
Example 10
Instead of SBH as a reducing agent, 0.5% by weight of sodium hypophosphite monohydrate (NaH ₂ PO ₂ .H ₂ O) was added to the reaction crude (copper content in the adsorption treatment solution: 0.31 ppm). When the vacuum distillation was performed in the same manner as in Example 9 except that the crude reaction product was added, the copper content contained in the can after the distillation was 2.8 ppm, and the amount of aldehyde compound in the main fraction Was 2.5 ppm.
[0060]
Example 11
Using a large glass column (inner diameter 40 mm, length 1.5 m) filled with 1.5 L of “granular activated carbon A” using 12 kg of the reaction crude product (copper content 3.8 ppm) obtained in Production Example 3 as a raw material. Then, while the reaction crude product was kept at 100 ° C., liquid was passed in a column downward flow at a space velocity of 4 h ⁻¹ (feed rate = 6 L / h) to perform a copper adsorption treatment. This adsorption-treated reaction crude product (copper content 0.39 ppm) was subjected to batch distillation apparatus (20 L capacity) with an initial fraction of 20% until the boiling point range reached 170 ° C / 15 mmHg (liquid temperature to 190 ° C). Distillation was performed to obtain 9.2 kg of a topping product (copper content: 0.49 ppm) having a 1,4-CHDM purity of 96.8%.
[0061]
Furthermore, 9 kg of the topping product was used as a raw material, and vacuum distillation was performed using a continuous distillation apparatus. That is, the topping product was continuously supplied at a rate of 1 L / h to a 10-stage theoretical distillation column packed with regular packing for rectification (SUS316), and the reflux ratio ( R / D) = 2, reduced pressure 15 mmHg, distillation temperature 170 ° C., can liquid temperature 185 ° C., main fraction from the tower top is about 0.9 L / h, high boiling point content from the tower bottom is about 0 The sample was extracted continuously at a speed of 1 L / h. Perform vacuum distillation for 5 hours (copper content in the final can: 3.8 ppm), about 4.5 kg of the main fraction (1,4-CHDM purity: 99.7%), About 0.5 kg was obtained. The aldehyde content in the main fraction was 35 ppm.
[0062]
【The invention's effect】
By applying the conditions according to the present invention, it is possible to industrially produce high-quality CHDM with very little by-product of impure aldehyde.

Claims

General formula (1)

[Wherein, R represents a linear or branched alkyl group having 1 to 4 carbon atoms. The cyclohexanedicarboxylic acid dialkyl represented by] that is obtained by reduction in the presence of a copper-based catalyst formula (2)

When the reaction crude product containing cyclohexanedimethanol represented by the formula is distilled under reduced pressure, the content of copper contained in the can during distillation is maintained at 5 ppm or less from the start to the end of distillation. A method for producing cyclohexanedimethanol.

The content of copper contained in a reaction crude product containing cyclohexanedimethanol is reduced by adsorption treatment using an adsorbent, and then distilled under reduced pressure. Production method.

The method for producing cyclohexanedimethanol according to claim 2, wherein the copper content after the adsorption treatment is 1 ppm or less.

The method for producing cyclohexanedimethanol according to claim 2 or 3, wherein the adsorbent is one or more adsorbents selected from the group consisting of activated carbon, a porous inorganic compound, and a cation exchanger.

The cyclohexanedi according to any one of claims 1 to 4, which is distilled under reduced pressure in the presence of sodium borohydride, sodium hypophosphite or sodium hypophosphite hydrate. A method for producing methanol.

The method for producing cyclohexanedimethanol according to any one of claims 1 to 4, wherein distillation is performed under reduced pressure while controlling the temperature of the can liquid at 130 to 250 ° C.