JP4876349B2 - Method for producing (meth) acrylate having biphenyl skeleton - Google Patents

Description

【０００９】
式(3)において、ｎは１〜４の整数を表し、Ｒ²はアルキレン基を表し、Ｒ³〜Ｒ⁶は水素原子、アルキル基又はアルコキシアルキル基を表す。
Ｒ²のアルキレン基としては、エチレン基及びプロピレン基等を挙げることができる。Ｒ³〜Ｒ⁶がアルキル基である場合は、炭素数１〜６のものが好ましい。Ｒ³〜Ｒ⁶のアルコキシアルキル基としては、メトキシメチル基、メトキシエチル基、メトキシプロピル基、エトキシメチル基、エトキシエチル基及びエトキシプロピル基等を挙げることができる。
【００１０】
本発明では、（メタ）アクリル酸又は（メタ）アクリル酸ダイマー（以下、不飽和カルボン酸という）を使用する。
【００１１】
アルコールに対する不飽和カルボン酸の使用量は特に限定されるものではないが、エステル化反応の効率や反応生成物の精製の容易性を考慮すればアルコール分子１モルに対して、２．１〜４モル、好ましくは２．２〜２．５モルの範囲で用いられる。
【００１２】
エステル化反応は、常法に従えば良く、例えば、有機溶媒中で、酸触媒及びラジカル重合禁止剤の存在下に、アルコール及び不飽和カルボン酸を加熱攪拌する方法等が挙げられる。
【００１３】
酸触媒としては、原料として用いる不飽和カルボン酸よりも酸性度が大きいものであれば特に制限されないが、好ましいものとしては、塩酸、臭化水素酸、硫酸及びリン酸等の無機酸；ベンゼンスルホン酸、ｐ−トルエンスルホン酸、トリクロロ酢酸、シュウ酸及びギ酸等の有機酸又はそれらの塩；塩化亜鉛、塩化スズ、塩化第二鉄、塩化第二銅及び硫酸第二銅等のルイス酸；陽イオン交換樹脂並びに活性白土等を挙げることができる。これらの中でも、硫酸、リン酸、ｐ−トルエンスルホン酸及びｐ−トルエンスルホン酸ソーダが好ましい。
酸触媒の使用量は、一般的なエステル化反応における使用量に従えば良く、アルコール１モルに対して、０．０００１〜０．１モルが好ましく、０．００１〜０．０５モルがより好ましい。
【００１４】
ラジカル重合禁止剤としては、従来より知られている通常のラジカル重合禁止剤が使用され、ラジカルを捕捉しうる化合物であれば特に制限されない。好ましいものとしては、ハイドロキノン、メトキシハイドロキノン、エトキシハイドロキノン、メチルハイドロキノン、フェノチアジン、ｔ−ブチルカテコール及び次亜リン酸等が挙げられる。これらのラジカル重合禁止剤は単独で用いても良いし、２種類以上を併用しても良い。
ラジカル重合禁止剤は、通常は、不飽和カルボン酸に対して１０〜１００００ｐｐｍの範囲で使用することが好ましく、１００〜５０００ｐｐｍがより好ましい。
【００１５】
本発明におけるエステル化反応においては、エステル化反応を容易に進行させ、又結晶中の酸触媒及び未反応物の量を低減し、後の精製工程を容易にすることができるため、有機溶媒を使用することが好ましい。
有機溶媒としては、原料として使用される不飽和カルボン酸と反応するもの、例えば、アルコール類やアミン類等を除けば特に限定されるものではないが、エステル化反応においては、生成する水を反応系外に留去することが好ましいことから、系内で生成した水を系外に容易に留去できる溶媒、即ち、水に不溶であり、かつ水と共沸するような有機溶媒が好ましい。当該有機溶媒の例としては、ベンゼン、トルエン、キシレン、キュメン、ジクロロエタン及びトリクロロエタン等を挙げることができる。これらの中でも、水と近い沸点を有し、水との共沸性が良く、しかも安価で比較的環境への負荷が少ないトルエンが特に好ましい。
有機溶媒の使用量は、特に限定されるものではないが、通常はアルコールと不飽和カルボン酸との合計重量に対して、５質量倍以下が好ましく、より好ましくは０．８〜２質量部以下である。５質量倍を超えると結晶の収率が低下する場合がある。
【００１６】
エステル化反応の反応温度としては、通常７０〜１５０℃、好ましくは１００〜１３５℃の範囲で行われる。反応は通常、常圧下で行われるが、用いる有機溶媒の沸点によっては、反応温度が前記温度範囲内になるように、加圧又は減圧下で行っても良い。本発明において反応時間は特に限定されるものではないが、通常、１〜２０時間の範囲で行われる。
【００１７】
本発明では、エステル化反応後の反応液を５０〜１００℃に維持し、これに水（以下洗浄水という）を添加して洗浄する。反応液の温度が５０℃に満たない場合は、反応液に洗浄水を添加すると、生成物の（メタ）アクリレートが直ちに固化してしまい、他方反応液の温度が１００℃を超えると洗浄水による洗浄が困難となる。
【００１８】
洗浄水としては、反応液に洗浄水を添加したときに(メタ）アクリレートが結晶化することを防止することができるため、加熱されているものが好ましい。洗浄水の温度としては、４０〜１００℃が好ましく、より好ましくは６０〜９０℃である。洗浄水の温度が４０℃より低いと、反応液に洗浄水を添加したときに(メタ）アクリレートが結晶化してしまう場合がある。
【００１９】
洗浄水としては、アンモニア、アミン類及び水酸化ナトリウム等の塩基性物質を含まないものが好ましい。塩基性物質を含む洗浄水を使用した場合、前記水洗は比較的高温で行われるため、得られた(メタ）アクリレートが加水分解反応を引き起こす場合がある。
【００２０】
洗浄水の使用量は特に限定されないが、一般的には反応液に対して、１／１０倍量〜１倍量（質量基準）を用いることが好ましい。尚、反応液に含まれる酸触媒や不飽和カルボン酸の量が多い場合は、洗浄操作を何回か繰り返せば良い。洗浄回数は、酸価、ｐＨ等を確認しながら適宜設定すれば良い。
【００２１】
前記水洗工程においては、本発明で得られる(メタ）アクリレートが疎水性が高く、反応液からなる有機層と水層の２層に容易に分離するため、分液操作で水層を除去して洗浄を繰り返えせば良い。又、洗浄終了後は分液操作で有機層を分離することができる。
【００２２】
洗浄操作で使用する容器又は装置（以下洗浄装置という）としては、実験室スケールのような小規模では分液漏斗のような分液操作が容易に行えるものが良く、工業的スケールでは装置下部にドレーンバルブ等、液抜きが容易な反応装置を、洗浄装置として使用することが好ましい。
分液操作における洗浄装置内壁の温度としては、液温と等温か、又はこれより高温であることが好ましい。洗浄装置内壁の温度が液温より低いと、内壁に接する液部分が結晶化して分液操作が困難になる場合がある。
【００２３】
洗浄後に分液操作で分離された有機層を、蒸発・蒸留等の方法で濃縮することにより、粉末状の(メタ）アクリレートを得ることができる。
【００２４】
この時点において、(メタ）アクリレート中に微量の未反応不飽和カルボン酸等の残存酸成分を含有している場合には、臭気や腐食等の問題を生ずることがあるため、残存酸成分を中和する。
中和方法としては、粉末状で得られた(メタ）アクリレートを、攪拌機を有する容器又は装置に移し、これに攪拌下に水を添加して懸濁状態の液とし、これに塩基性物質を含む水溶液（以下塩基性水溶液という）を少量づつ添加する方法等が挙げられる。
【００２５】
塩基性水溶液に使用される塩基性物質としては、アンモニア、アミン、水酸化ナトリウム及び水酸化カリウム等が挙げられる。塩基性水溶液中の塩基性物質濃度としては、目的に応じて適宜設定すれば良いが、濃度が高い場合には凝集や、(メタ）アクリレートの加水分解等を引き起こす場合があるため、低濃度であることが好ましい。好ましくは２０質量％以下であり、より好ましくは１０質量％以下である。
【００２６】
この場合、（メタ）アクリレートの重合を防止するため、懸濁液に重合禁止剤を添加することが好ましい。重合禁止剤の使用量は特に限定されないが５０ｐｐｍ〜１０００ｐｐｍ程度が一般的である。
このとき、懸濁液を加温することが可能であるが、本工程においては加水分解を防ぐという観点からは高温下での操作は避けることが好ましい。
【００２７】
塩基性水溶液の添加方法としては、懸濁液のｐＨを連続的に測定しつつ、攪拌下に塩基性水溶液を滴下することが好ましい。攪拌における攪拌速度や攪拌翼の形態は特に限定されず、液全体が均一に攪拌できるものであれば良い。又、攪拌時間も（メタ）アクリレート中に含まれる酸性不純物量等に応じて適宜設定すれば良く、局所的な中和が起こらず、系全体のｐＨが均一であれば長時間の攪拌をする必要はない。中和後のｐＨとしては３〜１０が好ましく、より好ましくは４〜７である。ｐＨが３に満たない場合は、残存する酸の臭気や腐食といった問題が発生し、逆にｐＨが１０より大きいと、（メタ）アクリレートの加水分解が発生したり、（メタ）アクリレートの硬化物に着色が発生する場合がある。
このようにして得られた懸濁液を濾過等の操作により、固体の（メタ）アクリレートを分離する。
【００２８】
本発明においては、前記洗浄工程の後、好ましくは乾燥を行なう。
乾燥工程においては、種々の乾燥機が使用できるが、短時間で効率よく水分や有機溶媒を除去するという目的から、真空乾燥機を使用することが好ましい。乾燥時間は特に制限されないが、残存する水分やその他揮発成分を完全に除去するためには、乾燥時間は１〜４８時間が好ましく、この時は加熱しても良い。ただし、嫌気条件下であるため重合反応が起こりやすくなるため、加温は１００℃を超えないことが好ましい。
洗浄で用いた水は乾燥に時間を要するため、乾燥操作の前に、メタノールやアセトンといった低沸点で水との相溶性の高い有機溶剤で洗浄することもできる。
【００２９】
本発明の製造方法は、結晶性が高く疎水性の強い下記(1)又は(2)で示されるビフェニル骨格を有する(メタ）アクリレートの製造方法である。
【００３０】
【化５】

【００３１】
〔式(1)において、ｎは１〜４の整数を表し、Ｒ¹は水素原子又はメチル基を表し、Ｒ²はアルキレン基を表し、Ｒ³〜Ｒ⁶は水素原子、アルキル基又はアルコキシアルキル基を表す。〕
【００３２】
【化６】

【００３３】
〔式(2)において、ｎは１〜４の整数を表し、Ｒ¹及びＲ⁷は水素原子又はメチル基を表し、Ｒ²はアルキレン基を表し、Ｒ³〜Ｒ⁶は水素原子、アルキル基又はアルコキシアルキル基を表す。〕
【００３４】
式(1)及び式(2)におけるＲ²〜Ｒ⁶の具体例としては、前記と同様のものが挙げられる。
【００３５】
【実施例】
以下に実施例及び比較例を挙げ、本発明をより具体的に説明する。尚、以下において「％」とは、質量％を意味する。
○実施例１
ディーンスターク管、冷却管、温度計及び攪拌機を備えた３Ｌ容量の３つ口フラスコに、トルエン８００ｍＬ、ｐ−トルエンスルホン酸ソーダ３２．６１ｇ（０．１７１モル）、メトキシハイドロキノン０．８０ｇ、ビフェニルのエチレンオキサイド付加物〔前記式(3)において、Ｒ²がエチレン基、Ｒ³〜Ｒ⁶が水素原子、ｎ＝１の化合物〕５００ｇ（１．８２５モル）及びアクリル酸３１５ｇ（４．３８０モル）を仕込み、攪拌しながら、１３５℃まで昇温し、３時間反応させた。
反応終了後、反応液を７０℃に冷却し、これをあらかじめ加温しておいた分液漏斗に移し、７０℃に加温した水３００ｇを加えた。分液漏斗を振った後に静置し、有機層と水層とを分離させた後に有機層のみを回収した。同様の操作を３回繰り返した後に、有機層を減圧蒸留によりトルエンを除去し、ジアクリレートの固体を得た。
次いで、この固体にハイドロキノン０．１ｇを溶解させた水７００ｇを加えて攪拌した後にｐＨを測定したところ約２であった。この懸濁液に５％アンモニア水を滴下していくと、１０ｍLを滴下したときに懸濁液のｐＨは６になったので、アンモニア水の添加を中止した。アンモニア水添加後の懸濁液をブフナー漏斗を使用して濾過し、結晶と液とに分離した。
次に得られた結晶を４０℃の減圧乾燥機で１２時間乾燥させた。
最終的に得られた結晶の酸価を測定したところ、＜０．０１meq／ｇであり、重量は６１２ｇ（収率８７％）であった。
得られた生成物について、融点、元素分析及び¹Ｈ ＮＭＲスペクトル（２７０ＭＨｚ、測定溶媒ＣＤＣｌ₃）の測定を行なった結果は、以下の通りであり、目的物であることが確認された。
【００３６】
○融点：９４〜９６℃
○元素分析（％）
計算値：Ｃ；６９．１０、Ｈ；５．８０、Ｏ；２５．１０
実測値：Ｃ；６８．６３、Ｈ；６．１２、Ｏ；２５．２３
【００３７】
¹Ｈ ＮＭＲスペクトルの帰属
実施例１により得られたアクリレートの構造式を下記式(4)に示し、それぞれのプロトンにａ〜ｇの番号を付けた。帰属は表１の通りである。
【００３８】
【化６】

【００３９】
【表１】

【００４０】
○実施例２
ディーンスターク管、冷却管、温度計及び攪拌機を備えた１Ｌ容量の３つ口フラスコに、トルエン２００ｍＬ，ｐ−トルエンスルホン酸ソーダ１２．０６ｇ（０．０６３モル）、メトキシハイドロキノン０．２０ｇ、ビフェニルのエチレンオキサイド付加物１２８ｇ（０．４７モル）及びβ−アクリロキシプロピオン酸１４８．４ｇ（１．０３モル）を仕込み、攪拌しながら、１３０℃まで昇温し、４時間反応させた。
反応終了後、反応液を６０℃に冷却し、あらかじめ加温しておいた分液漏斗に移し、６０℃に加温した水１００ｇを加えた。分液漏斗を振った後に静置し、有機層と水層とを分離させた後に有機層のみを回収した。同様の操作を３回繰り返した後に、有機層を減圧蒸留によりトルエンを除去し、ジアクリレートの固体を得た。
次いで、この固体にハイドロキノン０．１ｇを溶解させた水２５０ｇを加えて攪拌した後にｐＨを測定したところ約１であった。この懸濁液に５％アンモニア水を滴下していくと、３ｍLを滴下したときに懸濁液のｐＨが６になったので、ブフナー漏斗で濾過し、結晶と液に分離した。
次に結晶を４０℃の減圧乾燥機で１２時間乾燥させた。
最終的に得られた結晶の酸価を測定したところ、＜０．０１meq／ｇであり、重量は１７５ｇ（収率７１％）であった。
得られた生成物について、実施例１と同様に融点、元素分析及び¹Ｈ ＮＭＲスペクトルの測定を行なった結果は、以下の通りであり、目的物であることが確認された。
【００４１】
○融点：１４０〜１４２℃
○元素分析（％）
計算値：Ｃ；６３．８７、Ｈ；５．７４、Ｏ；３０．３９
実測値：Ｃ；６４．３３、Ｈ；６．１１、Ｏ；２９．５１
【００４２】
¹Ｈ ＮＭＲの帰属
実施例２で得られたアクリレートの構造式を下記式(5)に示し、それぞれのプロトンにａ〜ｉの番号を付けた。帰属は表２の通りである。
【００４３】
【化７】

【００４４】
【表２】

【００４５】
○比較例１
実施例２と同様のフラスコに、トルエン２００ｍＬ、ｐ−トルエンスルホン酸ソーダ８．０４ｇ（０．０４２モル）、メトキシハイドロキノン０．２０ｇ、ビフェニルのエチレンオキサイド付加物１２８ｇ（０．４７モル）及びアクリル酸７４．１ｇ（１．０３モル）を仕込み、攪拌しながら、１３０℃まで昇温し、３時間反応させた。
反応終了後、液温を６０℃まで冷却し、結晶が析出しないうちに、加水分解を防ぐためにあらかじめ氷浴で冷却しておいた０．５質量％水酸化ナトリウム水溶液に注いで中和を行なったが、混合と同時に反応液全体が固体となってしまい、固・液の２相となってしまった。又、液相は水のみであり、水相のｐＨは＞１１であった。
前記で得られた固相を濾過により分離し、これに１質量％硫酸アンモニウム水溶液４００ｍＬを加えて５分攪拌したところ、水層のｐＨは約３であった。この固体を５０℃で１２時間減圧乾燥を行い、１６１．５ｇ（収率８９．９％）の結晶を得た。得られた固体は強いアクリル酸臭を呈し、酸価も５．１meq／ｇと高く、実用に耐えうる品質ではなかった。
比較例では、前記水酸化ナトリウム水溶液による中和において、反応液がトルエンや未反応不飽和カルボン酸等を取り込み液全体が固化してしまったため、精製が困難であったものと考えられる。
【００４６】
【発明の効果】
本発明によれば、前記一般式(1)又は(2)で表されるビフェニル骨格を有する（メタ）アクリレートを高純度で製造することが可能となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a production method capable of producing (meth) acrylate having a biphenyl skeleton having high crystallinity and strong hydrophobicity with high purity, and is usefully used in the technical field for producing (meth) acrylate. Can do.
[0002]
[Prior art and problems to be solved by the invention]
(Meth) acrylate having a biphenyl skeleton is used as a component of thermosetting or active energy ray-curable compositions, and the cured product has excellent performance such as heat resistance, transparency, and low water absorption. It has been used for various applications such as waterproof paints, transparent acrylic plates, and liquid crystal materials used for waterproofing printed circuit boards constituting electronic circuits of products.
[0003]
However, since the (meth) acrylate has very high crystallinity and strong hydrophobicity, it has been difficult to produce with high purity.
That is, if the reaction liquid is cooled after esterifying the raw material alcohol and an unsaturated carboxylic acid such as (meth) acrylic acid, the obtained (meth) acrylate is immediately crystallized, so the next purification step is performed. It was difficult.
In order to solve this problem, there is a method of washing with an aqueous alkali solution such as an aqueous sodium hydroxide solution while the temperature of the reaction solution before the obtained (meth) acrylate is crystallized is high. The reason for using the alkaline aqueous solution for washing is to remove the acid catalyst used in the esterification reaction and the unreacted unsaturated carboxylic acid present in the reaction solution, but the washing is performed at a high temperature. Thus, the hydrolysis reaction of the obtained (meth) acrylate proceeds, and the reaction solution solidifies due to the high hydrophobicity of (meth) acrylate.
[0004]
The present inventors have intensively studied in order to find a production method capable of producing (meth) acrylate having a biphenyl skeleton having high crystallinity and strong hydrophobicity with high purity.
[0005]
[Means for Solving the Problems]
As a result of intensive investigations to solve the above-mentioned problems, the present inventors have found that a method of maintaining the liquid temperature at 50 to 100 ° C. after completion of the esterification reaction and adding water to the washing to remove the acid catalyst or not. The present invention was completed by finding out that a reactive unsaturated carboxylic acid or the like can be easily removed and a (meth) acrylate having a biphenyl skeleton can be produced with high purity.
Hereinafter, the present invention will be described in detail.
In the present specification, an acryloyl group or a methacryloyl group is represented as a (meth) acryloyl group, an acrylate or methacrylate is represented as a (meth) acrylate, and acrylic acid or methacrylic acid is represented as (meth) acrylic acid.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention causes first below general formula (3) and an alcohol having a biphenyl skeleton represented by (meth) acrylate Le acid or (meth) acrylic acid dimer esterification reaction.
[0007]
An alcohol having a biphenyl skeleton (hereinafter sometimes simply referred to as alcohol ) is an alcohol having a biphenyl skeleton represented by the following general formula (3) , and includes an alkylene oxide adduct of a bisphenol and an alkylene oxide adduct of a bisphenol derivative. Can be mentioned.
Here, examples of the alkylene oxide include ethylene oxide and propylene oxide. As the added number of alkylene oxides, those added with 1 to 8 are preferable. When nine or more alkylene oxides are added, the resulting (meth) acrylate is too hydrophilic, which may reduce the yield of the final product .
[0008]
[Formula 4]

[0009]
In the formula (3), n represents an integer of 1 to 4, R ² represents an alkylene group, and R ^{3 to} R ⁶ represent a hydrogen atom, an alkyl group, or an alkoxyalkyl group.
Examples of the alkylene group for R ² include an ethylene group and a propylene group. When R < ³ > -R < ⁶ > is an alkyl group, a C1-C6 thing is preferable. Examples of the alkoxyalkyl group of R ^{3 to} R ⁶ include a methoxymethyl group, a methoxyethyl group, a methoxypropyl group, an ethoxymethyl group, an ethoxyethyl group, and an ethoxypropyl group.
[0010]
In the present invention, a (meth) acrylic acid or (meth) acrylic acid dimer (hereinafter, referred to as unsaturated carboxylic acid).
[0011]
The amount of the unsaturated carboxylic acid used with respect to the alcohol is not particularly limited. However, in consideration of the efficiency of the esterification reaction and the ease of purification of the reaction product, it is 2.1 to 4 with respect to 1 mol of the alcohol molecule. It is used in the range of mol, preferably 2.2 to 2.5 mol.
[0012]
The esterification reaction may be carried out according to a conventional method, and examples thereof include a method in which an alcohol and an unsaturated carboxylic acid are heated and stirred in an organic solvent in the presence of an acid catalyst and a radical polymerization inhibitor.
[0013]
The acid catalyst is not particularly limited as long as it has higher acidity than the unsaturated carboxylic acid used as a raw material, but preferred are inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid and phosphoric acid; benzenesulfone Acids, organic acids such as p-toluenesulfonic acid, trichloroacetic acid, oxalic acid and formic acid or their salts; Lewis acids such as zinc chloride, tin chloride, ferric chloride, cupric chloride and cupric sulfate; Examples include ion exchange resins and activated clay. Among these, sulfuric acid, phosphoric acid, p-toluenesulfonic acid and p-toluenesulfonic acid soda are preferable.
The amount of the acid catalyst used may be according to the amount used in a general esterification reaction, and is preferably 0.0001 to 0.1 mol, more preferably 0.001 to 0.05 mol, relative to 1 mol of alcohol. .
[0014]
As the radical polymerization inhibitor, a conventionally known ordinary radical polymerization inhibitor is used, and it is not particularly limited as long as it is a compound capable of scavenging radicals. Preferable examples include hydroquinone, methoxyhydroquinone, ethoxyhydroquinone, methylhydroquinone, phenothiazine, t-butylcatechol and hypophosphorous acid. These radical polymerization inhibitors may be used alone or in combination of two or more.
Usually, it is preferable to use a radical polymerization inhibitor in the range of 10-10000 ppm with respect to unsaturated carboxylic acid, and 100-5000 ppm is more preferable.
[0015]
In the esterification reaction in the present invention, the esterification reaction can be easily advanced, the amount of acid catalyst and unreacted substances in the crystal can be reduced, and the subsequent purification step can be facilitated. It is preferable to use it.
The organic solvent is not particularly limited except that it reacts with the unsaturated carboxylic acid used as a raw material, for example, alcohols or amines, but in the esterification reaction, the water produced is reacted. Since it is preferable to distill out of the system, a solvent capable of easily distilling out water generated in the system out of the system, that is, an organic solvent which is insoluble in water and azeotropes with water is preferable. Examples of the organic solvent include benzene, toluene, xylene, cumene, dichloroethane and trichloroethane. Among these, toluene having a boiling point close to that of water, good azeotropy with water, low cost, and relatively low environmental burden is particularly preferable.
Although the usage-amount of an organic solvent is not specifically limited, Usually, 5 mass times or less is preferable with respect to the total weight of alcohol and unsaturated carboxylic acid, More preferably, 0.8-2 mass parts or less It is. If it exceeds 5 mass times, the yield of crystals may decrease.
[0016]
The reaction temperature for the esterification reaction is usually 70 to 150 ° C, preferably 100 to 135 ° C. The reaction is usually carried out under normal pressure, but depending on the boiling point of the organic solvent used, it may be carried out under pressure or reduced pressure so that the reaction temperature falls within the above temperature range. In the present invention, the reaction time is not particularly limited, but is usually 1 to 20 hours.
[0017]
In the present invention, the reaction liquid after the esterification reaction is maintained at 50 to 100 ° C., and water (hereinafter referred to as washing water) is added thereto for washing. When the temperature of the reaction liquid is less than 50 ° C., when washing water is added to the reaction liquid, the product (meth) acrylate immediately solidifies, and when the temperature of the reaction liquid exceeds 100 ° C., the washing water causes Cleaning becomes difficult.
[0018]
The washing water is preferably heated because it can prevent the (meth) acrylate from crystallizing when the washing water is added to the reaction solution. The temperature of the washing water is preferably 40 to 100 ° C, more preferably 60 to 90 ° C. If the temperature of the washing water is lower than 40 ° C., the (meth) acrylate may crystallize when the washing water is added to the reaction solution.
[0019]
As washing water, what does not contain basic substances, such as ammonia, amines, and sodium hydroxide, is preferred. When washing water containing a basic substance is used, since the washing with water is performed at a relatively high temperature, the obtained (meth) acrylate may cause a hydrolysis reaction.
[0020]
Although the usage-amount of washing water is not specifically limited, Generally, it is preferable to use 1/10 times-1 times amount (mass reference | standard) with respect to a reaction liquid. If the amount of acid catalyst or unsaturated carboxylic acid contained in the reaction solution is large, the washing operation may be repeated several times. What is necessary is just to set the frequency | count of washing | cleaning suitably, confirming an acid value, pH, etc.
[0021]
In the water washing step, the (meth) acrylate obtained in the present invention has high hydrophobicity and is easily separated into two layers of an organic layer and a water layer made of a reaction solution. Repeat washing. Further, after the washing is completed, the organic layer can be separated by a liquid separation operation.
[0022]
As a container or apparatus used for the cleaning operation (hereinafter referred to as a cleaning apparatus), a small scale such as a laboratory scale can easily perform a liquid separation operation such as a separatory funnel. It is preferable to use a reaction device such as a drain valve that can be easily drained as a cleaning device.
The temperature of the inner wall of the cleaning device in the liquid separation operation is preferably equal to or higher than the liquid temperature. If the temperature of the inner wall of the cleaning device is lower than the liquid temperature, the liquid portion in contact with the inner wall may crystallize, making it difficult to perform a liquid separation operation.
[0023]
A powdered (meth) acrylate can be obtained by concentrating the organic layer separated by a liquid separation operation after washing by a method such as evaporation and distillation.
[0024]
At this point, if the (meth) acrylate contains a small amount of residual acid components such as unreacted unsaturated carboxylic acid, problems such as odor and corrosion may occur. To sum up.
As a neutralization method, the (meth) acrylate obtained in powder form is transferred to a container or apparatus having a stirrer, and water is added to the suspension with stirring to form a suspension, and a basic substance is added thereto. The method of adding the aqueous solution (henceforth a basic aqueous solution) containing it little by little etc. is mentioned.
[0025]
Examples of the basic substance used in the basic aqueous solution include ammonia, amine, sodium hydroxide and potassium hydroxide. The concentration of the basic substance in the basic aqueous solution may be appropriately set according to the purpose. However, if the concentration is high, it may cause aggregation or hydrolysis of (meth) acrylate. Preferably there is. Preferably it is 20 mass% or less, More preferably, it is 10 mass% or less.
[0026]
In this case, in order to prevent polymerization of (meth) acrylate, it is preferable to add a polymerization inhibitor to the suspension. Although the usage-amount of a polymerization inhibitor is not specifically limited, About 50 ppm-1000 ppm are common.
At this time, the suspension can be heated, but in this step, it is preferable to avoid an operation at a high temperature from the viewpoint of preventing hydrolysis.
[0027]
As a method for adding the basic aqueous solution, it is preferable to drop the basic aqueous solution dropwise with stirring while continuously measuring the pH of the suspension. The stirring speed in stirring and the form of the stirring blade are not particularly limited as long as the entire liquid can be stirred uniformly. Further, the stirring time may be appropriately set according to the amount of acidic impurities contained in the (meth) acrylate, and if the pH of the whole system is uniform without local neutralization, stirring for a long time is performed. There is no need. The pH after neutralization is preferably 3 to 10, more preferably 4 to 7. If the pH is less than 3, problems such as odor and corrosion of the remaining acid occur. Conversely, if the pH is higher than 10, hydrolysis of (meth) acrylate occurs or a cured product of (meth) acrylate. In some cases, coloring may occur.
Solid (meth) acrylate is separated from the suspension thus obtained by an operation such as filtration.
[0028]
In the present invention, drying is preferably performed after the washing step.
In the drying process, various dryers can be used, but it is preferable to use a vacuum dryer for the purpose of efficiently removing moisture and organic solvent in a short time. The drying time is not particularly limited, but the drying time is preferably 1 to 48 hours in order to completely remove the remaining moisture and other volatile components, and at this time, heating may be performed. However, since the polymerization reaction is likely to occur because of anaerobic conditions, it is preferable that the heating does not exceed 100 ° C.
Since the water used for washing requires time for drying, it can be washed with an organic solvent having a low boiling point and high compatibility with water, such as methanol or acetone, before the drying operation.
[0029]
Production method of the present invention is a method for producing (meth) acrylates having a biphenyl skeleton represented by the strong crystallinity of highly hydrophobic following (1) or (2).
[0030]
[Chemical formula 5]

[0031]
[In the formula (1), n represents an integer of 1 to 4, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group, and R ^{3 to} R ⁶ represent a hydrogen atom, an alkyl group or an alkoxyalkyl group. Represents a group. ]
[0032]
[Chemical 6]

[0033]
[In the formula (2), n represents an integer of 1 to 4, R ¹ and R ⁷ represent a hydrogen atom or a methyl group, R ² represents an alkylene group, and R ^{3 to} R ⁶ represent a hydrogen atom or an alkyl group. Or represents an alkoxyalkyl group. ]
[0034]
Specific examples of R ^{2 to} R ⁶ in formula (1) and formula (2) include the same as those described above.
[0035]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the following, “%” means mass%.
○ Example 1
To a 3 L three-necked flask equipped with a Dean-Stark tube, a cooling tube, a thermometer, and a stirrer, toluene 800 mL, p-toluenesulfonic acid soda 32.61 g (0.171 mol), methoxyhydroquinone 0.80 g, biphenyl Ethylene oxide adduct [R ² is an ethylene group, R ^{3 to} R ⁶ are hydrogen atoms, n = 1 compound] 500 g (1.825 mol) and acrylic acid 315 g (4.380 mol) The mixture was heated to 135 ° C. with stirring and reacted for 3 hours.
After completion of the reaction, the reaction solution was cooled to 70 ° C., transferred to a separatory funnel that had been heated in advance, and 300 g of water heated to 70 ° C. was added. After shaking the separatory funnel, the mixture was allowed to stand, and after separating the organic layer and the aqueous layer, only the organic layer was recovered. After repeating the same operation three times, toluene was removed from the organic layer by distillation under reduced pressure to obtain a diacrylate solid.
Next, 700 g of water in which 0.1 g of hydroquinone was dissolved in this solid was added and stirred, and then the pH was measured to be about 2. When 5% ammonia water was added dropwise to the suspension, the pH of the suspension reached 6 when 10 mL was added dropwise, so the addition of ammonia water was stopped. The suspension after addition of aqueous ammonia was filtered using a Buchner funnel to separate crystals and liquid.
Next, the obtained crystals were dried with a vacuum dryer at 40 ° C. for 12 hours.
When the acid value of the finally obtained crystal was measured, it was <0.01 meq / g, and the weight was 612 g (yield 87%).
The resulting product, mp, elemental analysis and ¹ H NMR spectrum (270 MHz, measurement solvent CDCl ₃₎ result of performing measurements are as follows, it was confirmed that it was a target product.
[0036]
○ Melting point: 94-96 ° C
○ Elemental analysis (%)
Calculated values: C; 69.10, H; 5.80, O; 25.10
Found: C; 68.63, H; 6.12, O; 25.23
[0037]
Assignment of ¹ H NMR spectrum The structural formula of the acrylate obtained in Example 1 is shown in the following formula (4), and numbers a to g are given to the respective protons. The attribution is as shown in Table 1.
[0038]
[Chemical 6]

[0039]
[Table 1]

[0040]
Example 2
To a 1 L three-necked flask equipped with a Dean-Stark tube, a cooling tube, a thermometer, and a stirrer, toluene 200 mL, p-toluenesulfonic acid soda 12.06 g (0.063 mol), methoxyhydroquinone 0.20 g, biphenyl The ethylene oxide adduct 128g (0.47mol) and (beta) -acryloxypropionic acid 148.4g (1.03mol) were prepared, and it heated up to 130 degreeC, making it react for 4 hours, stirring.
After completion of the reaction, the reaction solution was cooled to 60 ° C., transferred to a separatory funnel previously heated, and 100 g of water heated to 60 ° C. was added. After shaking the separatory funnel, the mixture was allowed to stand, and after separating the organic layer and the aqueous layer, only the organic layer was recovered. After repeating the same operation three times, toluene was removed from the organic layer by distillation under reduced pressure to obtain a diacrylate solid.
Next, 250 g of water in which 0.1 g of hydroquinone was dissolved in this solid was added and stirred, and then the pH was measured to be about 1. When 5% aqueous ammonia was added dropwise to the suspension, the pH of the suspension reached 6 when 3 mL was added dropwise, and the suspension was filtered through a Buchner funnel to separate crystals and liquid.
Next, the crystals were dried in a vacuum dryer at 40 ° C. for 12 hours.
When the acid value of the finally obtained crystal was measured, it was <0.01 meq / g and the weight was 175 g (yield 71%).
About the obtained product, the result of having measured melting | fusing point, elemental analysis, and < ¹ > H NMR spectrum like Example 1 was as follows, and it was confirmed that it was a target object.
[0041]
○ Melting point: 140-142 ° C
○ Elemental analysis (%)
Calculated values: C; 63.87, H; 5.74, O; 30.39
Found: C; 64.33, H; 6.11, O; 29.51
[0042]
¹ H NMR Assignment The structural formula of the acrylate obtained in Example 2 is shown in the following formula (5), and the numbers a to i are given to the respective protons. The attribution is as shown in Table 2.
[0043]
[Chemical 7]

[0044]
[Table 2]

[0045]
○ Comparative Example 1
In a flask similar to Example 2, 200 mL of toluene, 8.04 g (0.042 mol) of p-toluenesulfonic acid soda, 0.20 g of methoxyhydroquinone, 128 g (0.47 mol) of biphenyl ethylene oxide adduct and acrylic acid 74.1 g (1.03 mol) was charged, and the temperature was raised to 130 ° C. while stirring, and the mixture was reacted for 3 hours.
After completion of the reaction, the liquid temperature was cooled to 60 ° C. and neutralized by pouring into a 0.5% by mass aqueous sodium hydroxide solution that had been cooled in an ice bath in advance to prevent hydrolysis before crystals were precipitated. However, the whole reaction liquid became solid at the same time as mixing, and became two phases of solid and liquid. The liquid phase was only water, and the pH of the aqueous phase was> 11.
The solid phase obtained above was separated by filtration, and 400 mL of a 1% by mass ammonium sulfate aqueous solution was added thereto and stirred for 5 minutes. The pH of the aqueous layer was about 3. This solid was dried under reduced pressure at 50 ° C. for 12 hours to obtain 161.5 g (yield 89.9%) of crystals. The obtained solid had a strong acrylic acid odor and an acid value as high as 5.1 meq / g, which was not of a quality that could withstand practical use.
In the comparative example, in the neutralization with the aqueous sodium hydroxide solution, it was considered that purification was difficult because the reaction solution took in toluene, unreacted unsaturated carboxylic acid and the like and the entire solution was solidified.
[0046]
【Effect of the invention】
According to the present invention, it is possible to produce a (meth) acrylate having a biphenyl skeleton represented by the general formula (1) or (2) with high purity.

Claims (4)

Following general formula (3) and an alcohol having a biphenyl skeleton represented by (meth) acrylic Le acid by esterification reaction or the production of (meth) acrylates having a biphenyl skeleton represented by the following general formula (1) Or
A method for producing a (meth) acrylate having a biphenyl skeleton represented by the following general formula (2) by subjecting an alcohol having a biphenyl skeleton represented by the following general formula (3) and a (meth) acrylic acid dimer to an esterification reaction Because
A method for producing a (meth) acrylate having a biphenyl skeleton, characterized in that after the esterification reaction, the reaction solution is maintained at 50 to 100 ° C., and water is added thereto for washing.

In [Equation (3), n represents an integer of 1 to 4, R ² represents an alkylene group, R ³ to R ⁶ represents a hydrogen atom, an alkyl group or an alkoxyalkyl group. ]

[In the formula (1), n represents an integer of 1 to 4, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group, and R ^{3 to} R ⁶ represent a hydrogen atom, an alkyl group or an alkoxyalkyl group. Represents a group. ]

[In the formula (2), n represents an integer of 1 to 4, R ¹ and R ⁷ represent a hydrogen atom or a methyl group, R ² represents an alkylene group, and R ^{3 to} R ⁶ represent a hydrogen atom or an alkyl group. Or represents an alkoxyalkyl group. ] Method for producing a (meth) acrylate having a biphenyl skeleton according to claim 1, wherein the water added to the reaction solution does not contain a basic substance. After adding water to a reaction liquid, it wash | cleans in the state which maintained the liquid temperature after addition at 50-100 degreeC, The (meth) acrylate which has biphenyl skeleton of Claim 1 or Claim 2 characterized by the above-mentioned. Production method. The method for producing a (meth) acrylate having a biphenyl skeleton according to any one of claims 1 to 3 , wherein a basic substance is added to the (meth) acrylate after washing with water.