JP4250780B2 - Method for producing mercaptocarboxylic acids - Google Patents
Method for producing mercaptocarboxylic acids Download PDFInfo
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- JP4250780B2 JP4250780B2 JP04614498A JP4614498A JP4250780B2 JP 4250780 B2 JP4250780 B2 JP 4250780B2 JP 04614498 A JP04614498 A JP 04614498A JP 4614498 A JP4614498 A JP 4614498A JP 4250780 B2 JP4250780 B2 JP 4250780B2
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Description
【0001】
【産業上の利用分野】
本発明は高収率でメルカプトカルボン酸類の製造するとともに高純度、高収率で副生物を回収する方法に関する。メルカプトカルボン酸類は分子内に存在するメルカプト基とカルボキシル基により、反応性に富み、有機溶媒にも水にもよく溶解する特徴を有し、農薬、医薬をはじめとする有機合成品の原料として、また、塩化ビニルの安定剤、エポキシ樹脂やアクリル酸エステルポリマーの架橋剤、プラスチックレンズモノマーなどの原料として有用な化合物である。
【0002】
【従来の技術】
メルカプトカルボン酸の製造法としては、一般的には、不飽和ニトリル類からメルカプトニトリル類を得、次いで、メルカプトニトリル類を加水分解する方法が知られている。
【0003】
例えば、特開昭58−198460号公報では所定の条件下にアクリロニトリルを水硫化ナトリウム水溶液に加え、得られたβ−メルカプトプロピオニトリルのナトリウム塩を塩酸で中和、加水分解することによりβ−メルカプトプロピオン酸を得る方法が提案されている。ここでは、副生物であるチオジプロピオン酸の生成を抑えてβ−メルカプトプロピオン酸を収率よく得ることができるとされている。しかし、この方法では、中和加水分解により食塩と塩化アンモニウムの混合液ができるため、水溶液は有効利用できず、また、廃水処理が困難である。
【0004】
また、特開平4−305563号公報によればβ−メルカプトニトリル類のアルカリ塩を水酸化アルカリ水溶液中に加えて加水分解することによりβ−メルカプトプロピオン酸を得る方法が提案されている。ここでは、副生物であるチオジプロピオン酸の生成を抑えてβ−メルカプトプロピオン酸を極めて高収率で得ることができるとされているが、加水分解反応時の滴下方法、温度、時間などが厳しく制限されており、また、反応に長時間を要し、実際の工業化には不適切であるなどの問題点を有している。
【0005】
さらに、特開昭63−6545号公報によれば、硫化ナトリウムと遊離の水酸化ナトリウムに、撹拌下アクリロニトリルを滴下して反応させ、さらに反応溶液を加熱して比較的短時間に加水分解し、この間に生じるアンモニアガスを水に吸収して回収し、硫酸で中和後、副生成物としてほぼ純粋の芒硝を得ることができるとされているが、この方法では、過酷な条件で反応を行うため、不純物の生成が多く、目的とするβ−メルカプトプロピオン酸の収率は不十分である。また、窒素化合物の環境への影響から芒硝中の硫酸アンモニウムの量が厳しく規制されているが、この方法ではアンモニアの系外への除去が不完全であり、得られる芒硝にはかなりの硫酸アンモニウムが含まれており、さらに高純度化が望まれている。
【0006】
【発明が解決しようとする課題】
本発明者らは不飽和ニトリルと水硫化アルカリの反応、及び、その反応液の加水分解によるメルカプトカルボン酸類の製法について検討した結果、反応、加水分解、副生物分離、精製等の各工程の条件、及び、方法を改良することにより、従来公知の方法の問題点を解決し、高収率で目的物を得、副生物を高純度品として回収できることを知った。
【0007】
従来公知の塩酸、硫酸などの鉱酸水溶液による加水分解では、その反応条件が加熱還流条件であるなど、比較的高温を要するため、目的とするメルカプトカルボン酸類の収率が著しく低下し、目的としない副生物が多く生成する。
【0008】
また、無機塩基による加水分解反応についても従来の方法では100℃以上の高温で行われており、メルカプトニトリル類のα−活性水素の存在により硫化水素が脱離して不飽和ニトリル類が生成し、この不飽和ニトリル類がメルカプトニトリル類と反応して、結果的にチオジカルボン酸類となる等の副反応が起こりやすいという欠点を有している。
【0009】
従って、不飽和ニトリルと水硫化アルカリを原料としてメルカプトカルボン酸類を高収率で得るためには、チオジカルボン酸類等の副反応生成物の生成を抑えることが大きな課題である。
【0010】
【課題を解決するための手段】
本発明者らは、加水分解反応時にメルカプトカルボン酸類のみを高収率で得るために不飽和ニトリルと水硫化アルカリとの反応、及び、該反応液の塩基性加水分解反応について鋭意検討した結果、特定の条件下で反応することによりチオジカルボン酸類の副生を抑え、メルカプトカルボン酸類を高収率で得ることができることを見出した。
【0011】
また、水硫化アルカリと無機塩基を一括混合した溶液に不飽和ニトリルを加えて反応するのではなく、まず、水硫化アルカリと不飽和ニトリルとを反応させた後、無機塩基により加水分解することにより、安定に高収率にてメルカプトカルボン酸類を得ることのできることを知った。
【0012】
さらに、反応系を減圧とし、反応で生成したアンモニアを反応系外に除去、水に吸収させて回収することで、高純度のアンモニア水を得ることができ、また、メルカプトカルボン酸類のアルカリ塩を酸にて中和、分液して油層と水層を分離後、水層中に溶存しているメルカプトカルボン酸類を有機溶媒にて抽出してメルカプトカルボン酸類を得ることで、抽出後の水層から有機化合物、及び、窒素化合物をほとんど含まない高純度の無機塩水溶液を得ることができることを知り、本発明を完成した。
【0013】
本発明に使用される一般式(1)で表される不飽和ニトリルとしては、アクリロニトリル、2−フェニルプロペンニトリル、3−ブテンニトリル、5−ペンテンニトリル、3−フェニルプロペンニトリル、2−メチル−3−フェニルプロペンニトリル、3−フェニル−3−ブテンニトリル、2−エチル−5−ヘキセンニトリル、2−メチル−4−ペンテンニトリル、2−メチル−3−ブテンニトリル等が挙げられる。
【0014】
以下、本発明について詳細に説明するが、説明を簡単にするために不飽和ニトリルとしてアクリロニトリルを使用してβ−メルカプトプロピオン酸を製造する場合を代表例として述べる。
【0015】
本発明において使用される水硫化アルカリとしては、例えば、水硫化ナトリウム、水硫化カリウム、水硫化カルシウム等が挙げられる。また、硫黄や多硫化アルカリ、例えば多硫化ナトリウム、多硫化カリウム、多硫化カルシウム等が挙げられる。
【0016】
水硫化アルカリや多硫化アルカリの使用量は不飽和ニトリルに対して、1.0〜2.0倍モルが好ましい。1.0倍モル以下ではチオジニトリル類が多量に副生し、2.0倍モルより多い使用は反応後の中和に要する酸の使用量も増加し不経済となる。
【0017】
また、本発明において使用される無機塩基とは一般的にアルカリ金属水酸化物・炭酸塩・炭酸水素塩を言い、例えば、水酸化ナトリウム、水酸化カリウム、炭酸ナトリウム、炭酸カリウム、炭酸水素ナトリウム、炭酸水素カリウム等が使用される。系内において無機塩基を生成することもできる化合物も本発明の無機塩基の範疇に含まれる。例えば、硫化アルカリや硫化アルカリと硫黄の混合物などは系内の水と反応してアルカリ金属水酸化物を生成しうるので本発明の範疇に含まれる。これらのうち反応速度論的観点からアルカリ金属水酸化物が好ましく用いられ、その使用量は不飽和ニトリルに対して、1.0〜2.0倍モルが好ましい。1.0倍モル以下では未反応のメルカプトニトリルが残留し、2.0倍モルより多い使用は反応後の中和に要する酸の使用量も増加し不経済となる。
【0018】
加水分解の際に、不飽和ニトリルと水硫化アルカリとの反応で得られた反応液と無機塩基水溶液とを一括混合しても、無機塩基水溶液を該反応液に滴下しても、該反応液を無機塩基水溶液に滴下してもよいが、生産性や操作性の観点から、該反応液と無機塩基水溶液とを一括混合するか無機塩基水溶液を該反応液に滴下するのが好ましい。
【0019】
加水分解反応は100℃以下、好ましくは45℃〜80℃、より好ましくは60℃〜80℃で行う。45℃以下では反応は十分に進まず未反応のメルカプトニトリル類が残留し、80℃より高い温度では加水分解と同時にチオジカルボン酸類などが副生し、好ましくない。また、加水分解時間は1時間〜6時間が好ましく、2時間〜4時間がより好ましい。1時間以下では安定に高収率で目的とするメルカプトカルボン酸類を得ることができないことがあり、また、6時間以上反応しても特に効果は見られず生産性の面から好ましくない。
【0020】
加水分解反応後、反応溶液中には加水分解で生じたアンモニアが溶存している。アンモニアの存在は中和の際にアンモニウム塩を副生させる原因となり、高純度芒硝等の無機塩基の商品価値を著しく低下させるだけでなく、アンモニウム塩を含有することで公害処理は煩雑になり、極めて不経済である。
【0021】
従って、加水分解反応後、反応系から生成したアンモニアを反応系外に除去、回収する必要がある。アンモニアの除去には、不活性気体の反応溶液中へのバブリングや系を減圧とすることが好ましく、反応溶液中の溶存濃度が1000ppm以下、好ましくは100ppm以下になるまでアンモニアを除去する。除去されるアンモニアは水に吸収させることで、高純度、高濃度のアンモニア水を容易に得ることができる。
【0022】
アンモニアを回収した後、反応溶液中においてメルカプトカルボン酸類はアルカリ金属塩として存在する。したがって、メルカプトカルボン酸類の単離はまず酸を加えて中和、分液し、油層を蒸留するという一般的方法で行うことができる。中和に使用する鉱酸としては塩酸、硫酸、リン酸などが用いられる。
【0023】
中和後得られる水層には、メルカプトカルボン酸類が溶存しているため、水層から有機溶媒により抽出し、有機層は、例えば、減圧蒸留により留去し目的とするメルカプトカルボン酸類を得ることができる。また、中和後の反応液を一括して有機溶媒で抽出し、有機溶媒からメルカプトカルボン酸類を得ることもできる。ここで使用される有機溶媒としては、酢酸エチル、酢酸ブチル、クロロホルム、ジクロロメタン、ジエチルエーテル、イソプロピルエーテル、メチルエチルケトン、イソブチルケトン等が用いられ、酢酸エチル、酢酸ブチル等が好ましく用いられる。
【0024】
また、抽出後に得られる溶液は高濃度の芒硝、あるいは、食塩などの無機塩水溶液であり、例えば、高純度の芒硝水溶液として使用できる。また、高濃度の芒硝液から結晶を析出させれば、析出した結晶は非常に高純度の芒硝として使用できる。さらに、廃液もほとんど有機物や窒素化合物を含まないことから、環境への影響もなく公害処理も非常に簡便で経済的である。
【0025】
【実施例】
以下、実施例、及び比較例により本発明を詳しく説明するが、本発明はこれら実施例のみになんら限定されるものではない。
【0026】
実施例1
アクリロニトリル(33.2g)を、45℃に保った37%水硫化ナトリウム水溶液(130g)中に撹拌しながら45℃で2時間で滴下した後、同温度で1時間撹拌した。1時間後、48%水酸化ナトリウム水溶液(70g)を45℃〜50℃で撹拌しながら30分で滴下した。滴下終了後、80℃まで昇温し、同温度で2時間撹拌した。さらに、反応系を減圧し、同温度で3時間、脱アンモニアを行った。ここで、回収率99.9%で52.6gのアンモニア水を得た。反応溶液を室温まで冷却後、62.5%硫酸(150g)で中和し、酢酸エチル200mLで2回抽出した。抽出液を合わせ、溶媒を減圧で除去した。高速液体クロマトグラフィーによる分析の結果、β−メルカプトプロピオン酸が収率85%、チオジプロピオン酸が12%で生成していた。
【0027】
比較例1
アクリロニトリル(33.2g)を、45℃に保った37%水硫化ナトリウム水溶液(130g)中に撹拌しながら45℃で2時間で滴下した後、同温度で1時間撹拌した。1時間後、48%水酸化ナトリウム水溶液(71.5g)を45℃〜50℃で撹拌しながら30分で滴下した。滴下終了後、同温度で2時間撹拌した。反応溶液を室温まで冷却後、62.5%硫酸(150g)で中和し、酢酸エチル200mLで2回抽出した。抽出液を合わせ、溶媒を減圧で除去した。高速液体クロマトグラフィーによる分析の結果、β−メルカプトプロピオン酸が収率56%と著しく低く、また、チオジプロピオン酸が収率8%と未知化合物が多量に副生していた。
【0028】
比較例3
アクリロニトリル(33.2g)を、45℃に保った37%水硫化ナトリウム水溶液(130g)中に撹拌しながら45℃で2時間で滴下した後、同温度で1時間撹拌した。1時間後、48%水酸化ナトリウム水溶液(71.5g)を45℃〜50℃で撹拌しながら30分で滴下した。滴下終了後、80℃まで昇温し、同温度で2時間撹拌した。その後、さらに120℃まで昇温し、同温度で2時間撹拌した。反応溶液を室温まで冷却後、62.5%硫酸(150g)で中和し、酢酸エチル200mLで2回抽出した。抽出液を合わせ、溶媒を減圧で除去した。高速液体クロマトグラフィーによる分析の結果、β−メルカプトプロピオン酸が収率73%で得られたと同時に、チオジプロピオン酸が収率19%と未知化合物が多量に副生していた。
【0029】
比較例4
37%水硫化ナトリウム水溶液(130g)と48%水酸化ナトリウム水溶液(71.5g)を一括混合し、ここにアクリロニトリルを40〜45℃で撹拌しながら2時間で滴下した後、同温度で4時間撹拌した。その後、120℃まで3時間かけて昇温し、同温度で30分撹拌した。ここで、回収率50.0%で47.2gのアンモニア水を得た。反応溶液を室温まで冷却後、62.5%硫酸(150g)で中和し、酢酸エチル200mLで2回抽出した。抽出液を合わせ、溶媒を減圧で除去した。高速液体クロマトグラフィーによる分析の結果、β−メルカプトプロピオン酸が収率69%で得られたと同時に、チオジプロピオン酸が収率24%と多量に副生していた。
【0030】
【発明の効果】
以上のように、本発明に従って、水硫化アルカリ水溶液と不飽和ニトリル類を反応させ、次いで、無機塩基を加えて45℃〜80℃で加水分解反応を行うことにより、安定して高収率にてメルカプトカルボン酸類を得ることができる。加水分解反応後、反応系から生成したアンモニアを反応系外に反応溶液中の溶存濃度が1000ppm以下になるまでアンモニアを除去、除去されるアンモニアを水に吸収させて回収することで、高純度、高濃度のアンモニア水を容易に得ることができる。さらに、アンモニアを回収した後、酸を加えて中和、分液後、油層を濃縮後蒸留してメルカプトカルボン酸類を得ることができる。中和・分液時に得られる水層は高濃度の芒硝液等の無機塩基水溶液であり、例えば、この高濃度の芒硝液から結晶を析出させれば、析出した結晶は高純度の芒硝として使用できる。さらに、廃液もほとんど有機物を含まないことから、環境への影響もなく公害処理も非常に簡便で経済的である。[0001]
[Industrial application fields]
The present invention relates to a method for producing mercaptocarboxylic acids with high yield and recovering by-products with high purity and high yield. Mercaptocarboxylic acids are highly reactive due to the mercapto group and carboxyl group present in the molecule, and are well soluble in organic solvents and water. As raw materials for organic synthetic products such as agricultural chemicals and pharmaceuticals, Further, it is a compound useful as a raw material for a stabilizer of vinyl chloride, a crosslinking agent for an epoxy resin or an acrylic ester polymer, a plastic lens monomer, and the like.
[0002]
[Prior art]
As a method for producing mercaptocarboxylic acid, a method is generally known in which mercaptonitriles are obtained from unsaturated nitriles, and then mercaptonitriles are hydrolyzed.
[0003]
For example, in JP-A-58-198460, acrylonitrile is added to an aqueous sodium hydrosulfide solution under predetermined conditions, and the obtained sodium salt of β-mercaptopropionitrile is neutralized with hydrochloric acid and hydrolyzed to produce β- A method for obtaining mercaptopropionic acid has been proposed. Here, it is said that β-mercaptopropionic acid can be obtained with good yield by suppressing the production of thiodipropionic acid as a by-product. However, in this method, since a mixed solution of sodium chloride and ammonium chloride is formed by neutralization hydrolysis, the aqueous solution cannot be used effectively, and wastewater treatment is difficult.
[0004]
Japanese Patent Laid-Open No. 4-305563 proposes a method of obtaining β-mercaptopropionic acid by adding an alkali salt of β-mercaptonitrile to an aqueous alkali hydroxide solution and hydrolyzing it. Here, it is said that β-mercaptopropionic acid can be obtained in extremely high yield by suppressing the production of thiodipropionic acid as a by-product, but the dropping method, temperature, time, etc. during the hydrolysis reaction are There are problems such as being severely restricted, taking a long time for the reaction, and being inappropriate for actual industrialization.
[0005]
Furthermore, according to JP-A-63-6545, acrylonitrile is reacted dropwise with sodium sulfide and free sodium hydroxide with stirring, and the reaction solution is heated and hydrolyzed in a relatively short time. It is said that ammonia gas generated during this time is absorbed in water and recovered, and after neutralization with sulfuric acid, almost pure mirabilite can be obtained as a by-product. However, in this method, the reaction is performed under severe conditions. Therefore, many impurities are produced and the yield of the intended β-mercaptopropionic acid is insufficient. In addition, the amount of ammonium sulfate in mirabilite is severely regulated due to the environmental effects of nitrogen compounds, but this method is incomplete removal of ammonia out of the system, and the resulting mirabilite contains considerable ammonium sulfate. Therefore, higher purity is desired.
[0006]
[Problems to be solved by the invention]
As a result of examining the reaction of unsaturated nitrile with alkali hydrosulfide and the production method of mercaptocarboxylic acids by hydrolysis of the reaction solution, the present inventors have determined the conditions of each step such as reaction, hydrolysis, by-product separation, and purification. It has been found that, by improving the method, the problems of the conventionally known methods can be solved, the target product can be obtained in a high yield, and the by-product can be recovered as a high-purity product.
[0007]
In the conventional hydrolysis with a mineral acid aqueous solution such as hydrochloric acid and sulfuric acid, the reaction conditions are heating and reflux conditions, and a relatively high temperature is required. Therefore, the yield of the target mercaptocarboxylic acids is significantly reduced. Many by-products are generated.
[0008]
In addition, the hydrolysis reaction with an inorganic base is also performed at a high temperature of 100 ° C. or more in the conventional method, and hydrogen sulfide is eliminated due to the presence of α-active hydrogen of mercaptonitriles to produce unsaturated nitriles, The unsaturated nitriles react with the mercaptonitriles to result in side reactions such as thiodicarboxylic acids.
[0009]
Therefore, in order to obtain mercaptocarboxylic acids in high yields using unsaturated nitriles and alkali hydrosulfides as raw materials, it is a major issue to suppress the generation of side reaction products such as thiodicarboxylic acids.
[0010]
[Means for Solving the Problems]
As a result of earnestly examining the reaction of unsaturated nitrile with alkali hydrosulfide and the basic hydrolysis reaction of the reaction solution in order to obtain only the mercaptocarboxylic acids at a high yield during the hydrolysis reaction, It has been found that by reacting under specific conditions, by-products of thiodicarboxylic acids can be suppressed, and mercaptocarboxylic acids can be obtained in high yield.
[0011]
Rather than reacting by adding unsaturated nitrile to a solution in which alkali hydrosulfide and inorganic base are mixed together, first, alkali hydrosulfide and unsaturated nitrile are reacted and then hydrolyzed with inorganic base. It has been found that mercaptocarboxylic acids can be obtained stably at a high yield.
[0012]
Furthermore, by reducing the reaction system to a reduced pressure and removing the ammonia generated by the reaction from the reaction system and absorbing it into water to recover it, high-purity ammonia water can be obtained, and alkali salts of mercaptocarboxylic acids can be obtained. After separating the oil layer and aqueous layer by acid neutralization and separation, the mercaptocarboxylic acids dissolved in the aqueous layer are extracted with an organic solvent to obtain mercaptocarboxylic acids, so that the aqueous layer after extraction From this, it was found that a high-purity inorganic salt aqueous solution almost free of organic compounds and nitrogen compounds could be obtained, and the present invention was completed.
[0013]
Examples of the unsaturated nitrile represented by the general formula (1) used in the present invention include acrylonitrile, 2-phenylpropenenitrile, 3-butenenitrile, 5-pentenenitrile, 3-phenylpropenenitrile, and 2-methyl-3. -Phenylpropenenitrile, 3-phenyl-3-butenenitrile, 2-ethyl-5-hexenenitrile, 2-methyl-4-pentenenitrile, 2-methyl-3-butenenitrile and the like.
[0014]
Hereinafter, the present invention will be described in detail. In order to simplify the description, a case where β-mercaptopropionic acid is produced using acrylonitrile as an unsaturated nitrile will be described as a representative example.
[0015]
Examples of the alkali hydrosulfide used in the present invention include sodium hydrosulfide, potassium hydrosulfide, calcium hydrosulfide and the like. Moreover, sulfur and alkali polysulfide, for example, sodium polysulfide, potassium polysulfide, calcium polysulfide, etc. are mentioned.
[0016]
The amount of alkali hydrosulfide or alkali polysulfide used is preferably 1.0 to 2.0 times the mol of the unsaturated nitrile. If the amount is less than 1.0 times mol, a large amount of thiodinitriles are by-produced, and if the amount is more than 2.0 times mol, the amount of acid used for neutralization after the reaction increases, which is uneconomical.
[0017]
The inorganic base used in the present invention generally means an alkali metal hydroxide / carbonate / bicarbonate, such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, Potassium bicarbonate or the like is used. A compound capable of generating an inorganic base in the system is also included in the category of the inorganic base of the present invention. For example, alkali sulfide or a mixture of alkali sulfide and sulfur can be reacted with water in the system to produce an alkali metal hydroxide, and thus is included in the scope of the present invention. Of these, alkali metal hydroxides are preferably used from the viewpoint of reaction kinetics, and the amount used is preferably 1.0 to 2.0 times the mol of the unsaturated nitrile. If it is less than 1.0-fold mol, unreacted mercaptonitrile remains, and if it is more than 2.0-fold mol, the amount of acid used for neutralization after the reaction also increases, which is uneconomical.
[0018]
During the hydrolysis, the reaction solution obtained by the reaction of the unsaturated nitrile and the alkali hydrosulfide and the inorganic base aqueous solution can be mixed together, or the inorganic base aqueous solution can be added dropwise to the reaction solution. However, from the viewpoint of productivity and operability, the reaction solution and the inorganic base aqueous solution are preferably mixed at once or the inorganic base aqueous solution is preferably added dropwise to the reaction solution.
[0019]
The hydrolysis reaction is performed at 100 ° C. or lower, preferably 45 ° C. to 80 ° C., more preferably 60 ° C. to 80 ° C. Below 45 ° C, the reaction does not proceed sufficiently and unreacted mercaptonitriles remain, and at temperatures higher than 80 ° C, thiodicarboxylic acids and the like are by-produced simultaneously with hydrolysis, which is not preferable. The hydrolysis time is preferably 1 hour to 6 hours, and more preferably 2 hours to 4 hours. If it is less than 1 hour, the desired mercaptocarboxylic acid cannot be obtained stably in a high yield, and even if it reacts for more than 6 hours, no particular effect is seen, which is not preferable from the viewpoint of productivity.
[0020]
After the hydrolysis reaction, ammonia generated by the hydrolysis is dissolved in the reaction solution. The presence of ammonia causes by-production of ammonium salts during neutralization, not only significantly reduces the commercial value of inorganic bases such as high purity mirabilite, but also makes pollution treatment complicated by containing ammonium salts, It is extremely uneconomical.
[0021]
Therefore, after the hydrolysis reaction, it is necessary to remove and recover ammonia generated from the reaction system outside the reaction system. In order to remove ammonia, it is preferable that bubbling of inert gas into the reaction solution and the system be reduced in pressure, and ammonia is removed until the dissolved concentration in the reaction solution is 1000 ppm or less, preferably 100 ppm or less. By removing the ammonia to be removed by water, high purity and high concentration ammonia water can be easily obtained.
[0022]
After recovering ammonia, mercaptocarboxylic acids are present as alkali metal salts in the reaction solution. Accordingly, the mercaptocarboxylic acids can be isolated by a general method of adding an acid to neutralize and separate the solution and distilling the oil layer. As the mineral acid used for neutralization, hydrochloric acid, sulfuric acid, phosphoric acid and the like are used.
[0023]
Since the mercaptocarboxylic acids are dissolved in the aqueous layer obtained after neutralization, extraction from the aqueous layer with an organic solvent is performed, and the organic layer is distilled, for example, by distillation under reduced pressure to obtain the desired mercaptocarboxylic acids. Can do. Moreover, the reaction liquid after neutralization can be extracted together with an organic solvent, and mercaptocarboxylic acids can be obtained from the organic solvent. As the organic solvent used here, ethyl acetate, butyl acetate, chloroform, dichloromethane, diethyl ether, isopropyl ether, methyl ethyl ketone, isobutyl ketone and the like are used, and ethyl acetate, butyl acetate and the like are preferably used.
[0024]
Moreover, the solution obtained after extraction is high concentration mirabilite or an aqueous inorganic salt solution such as salt, and can be used as, for example, a high purity mirabilite aqueous solution. Further, if crystals are precipitated from a high concentration of mirabilite solution, the deposited crystals can be used as very high purity mirabilite. In addition, since the waste liquid contains almost no organic matter or nitrogen compound, pollution treatment is very simple and economical without affecting the environment.
[0025]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited only to these Examples.
[0026]
Example 1
Acrylonitrile (33.2 g) was added dropwise to a 37% aqueous sodium hydrosulfide solution (130 g) kept at 45 ° C. with stirring at 45 ° C. over 2 hours, and then stirred at the same temperature for 1 hour. After 1 hour, a 48% aqueous sodium hydroxide solution (70 g) was added dropwise over 30 minutes with stirring at 45 ° C to 50 ° C. After completion of the dropwise addition, the temperature was raised to 80 ° C. and stirred at the same temperature for 2 hours. Further, the reaction system was depressurized, and deammonia was performed at the same temperature for 3 hours. Here, 52.6 g of aqueous ammonia was obtained at a recovery rate of 99.9%. The reaction solution was cooled to room temperature, neutralized with 62.5% sulfuric acid (150 g), and extracted twice with 200 mL of ethyl acetate. The extracts were combined and the solvent was removed under reduced pressure. As a result of analysis by high performance liquid chromatography, β-mercaptopropionic acid was produced at a yield of 85% and thiodipropionic acid at 12%.
[0027]
Comparative Example 1
Acrylonitrile (33.2 g) was added dropwise to a 37% aqueous sodium hydrosulfide solution (130 g) kept at 45 ° C. with stirring at 45 ° C. over 2 hours, and then stirred at the same temperature for 1 hour. After 1 hour, a 48% aqueous sodium hydroxide solution (71.5 g) was added dropwise over 30 minutes with stirring at 45-50 ° C. After completion of dropping, the mixture was stirred at the same temperature for 2 hours. The reaction solution was cooled to room temperature, neutralized with 62.5% sulfuric acid (150 g), and extracted twice with 200 mL of ethyl acetate. The extracts were combined and the solvent was removed under reduced pressure. As a result of analysis by high performance liquid chromatography, β-mercaptopropionic acid was remarkably low in yield of 56%, and thiodipropionic acid was in yield of 8%, and a large amount of unknown compounds were by-produced.
[0028]
Comparative Example 3
Acrylonitrile (33.2 g) was added dropwise to a 37% aqueous sodium hydrosulfide solution (130 g) kept at 45 ° C. with stirring at 45 ° C. over 2 hours, and then stirred at the same temperature for 1 hour. After 1 hour, a 48% aqueous sodium hydroxide solution (71.5 g) was added dropwise over 30 minutes with stirring at 45 ° C to 50 ° C. After completion of the dropwise addition, the temperature was raised to 80 ° C. and stirred at the same temperature for 2 hours. Thereafter, the temperature was further raised to 120 ° C., and the mixture was stirred at the same temperature for 2 hours. The reaction solution was cooled to room temperature, neutralized with 62.5% sulfuric acid (150 g), and extracted twice with 200 mL of ethyl acetate. The extracts were combined and the solvent was removed under reduced pressure. As a result of analysis by high performance liquid chromatography, β-mercaptopropionic acid was obtained in a yield of 73%, and at the same time, thiodipropionic acid was produced in a yield of 19% and a large amount of unknown compounds were by-produced.
[0029]
Comparative Example 4
A 37% aqueous solution of sodium hydrosulfide (130 g) and a 48% aqueous solution of sodium hydroxide (71.5 g) were mixed together, and acrylonitrile was added dropwise thereto at 40 to 45 ° C. with stirring for 2 hours, and then at the same temperature for 4 hours. Stir. Then, it heated up over 120 hours to 120 degreeC, and stirred for 30 minutes at the same temperature. Here, 47.2 g of ammonia water was obtained at a recovery rate of 50.0%. The reaction solution was cooled to room temperature, neutralized with 62.5% sulfuric acid (150 g), and extracted twice with 200 mL of ethyl acetate. The extracts were combined and the solvent was removed under reduced pressure. As a result of analysis by high performance liquid chromatography, β-mercaptopropionic acid was obtained in a yield of 69%, and at the same time, thiodipropionic acid was by-produced in a large amount of 24%.
[0030]
【The invention's effect】
As described above, according to the present invention, an alkali hydrosulfide aqueous solution and an unsaturated nitrile are reacted, and then an inorganic base is added and a hydrolysis reaction is performed at 45 ° C. to 80 ° C., thereby stably achieving a high yield. Thus, mercaptocarboxylic acids can be obtained. After the hydrolysis reaction, the ammonia generated from the reaction system is removed from the reaction system until the dissolved concentration in the reaction solution is 1000 ppm or less, and the removed ammonia is absorbed into water and recovered, thereby obtaining high purity. High-concentration aqueous ammonia can be easily obtained. Furthermore, after recovering ammonia, the acid can be added for neutralization and liquid separation, and the oil layer can be concentrated and distilled to obtain mercaptocarboxylic acids. The aqueous layer obtained at the time of neutralization / separation is an aqueous solution of an inorganic base such as high-concentration mirabilite solution. it can. Furthermore, since the waste liquid contains almost no organic matter, pollution treatment is very simple and economical without affecting the environment.
Claims (8)
b.該反応液と無機塩基を混合、加熱し、減圧下で反応系から生成したアンモニアを反応溶液中の溶存濃度が1000ppm以下になるまで反応系外に除去、アンモニアを回収し;
c.次いで、得られた反応液を酸にて中和後、分液してメルカプトプロピオン酸類からなる油層を分離し、さらに、水層中に溶存しているメルカプトカルボン酸類を有機溶媒にて抽出してメルカプトカルボン酸類を含む有機溶媒層を分離し、有機溶媒層、及び、または油層からメルカプトカルボン酸を回収するか、または、中和液を有機溶媒で抽出してメルカプトカルボン酸を含む有機溶媒層を分離し、有機溶媒層からメルカプトカルボン酸を得;
d.抽出後の水層から高純度の無機塩水溶液を得ることを特徴とする一般式(2)(化2)
b. Mixing and heating the reaction solution and an inorganic base , removing ammonia generated from the reaction system under reduced pressure until the dissolved concentration in the reaction solution is 1000 ppm or less, and recovering ammonia ;
c. Next, the resulting reaction solution is neutralized with an acid, and then separated to separate an oil layer composed of mercaptopropionic acids. Further, mercaptocarboxylic acids dissolved in the aqueous layer are extracted with an organic solvent. Separate the organic solvent layer containing mercaptocarboxylic acids and recover the mercaptocarboxylic acid from the organic solvent layer and / or the oil layer, or extract the neutralized solution with an organic solvent to remove the organic solvent layer containing the mercaptocarboxylic acid. Separating and obtaining mercaptocarboxylic acid from the organic solvent layer ;
d. A high-purity inorganic salt aqueous solution is obtained from the aqueous layer after extraction.
b.該反応液と無機塩基を混合、加熱し、減圧下で反応系から生成したアンモニアを反応溶液中の溶存濃度が1000ppm以下になるまで反応系外に除去、アンモニアを回収し;
c.次いで、得られた反応液を酸にて中和後、分液してメルカプトプロピオン酸類からなる油層を分離し、さらに、水層中に溶存しているメルカプトカルボン酸類を有機溶媒にて抽出してメルカプトカルボン酸類を含む有機溶媒層を分離し、有機溶媒層、及び、または油層からメルカプトカルボン酸を回収するか、または、中和液を有機溶媒で抽出してメルカプトカルボン酸を含む有機溶媒層を分離し、有機溶媒層からメルカプトカルボン酸を得ることを特徴とする一般式(2)で示されるメルカプトカルボン酸類、及び、アンモニアの製造方法。a. Reacting an unsaturated nitrile represented by the general formula (1) with an alkali hydrosulfide;
b. Mixing and heating the reaction solution and an inorganic base , removing ammonia generated from the reaction system under reduced pressure until the dissolved concentration in the reaction solution is 1000 ppm or less, and recovering ammonia ;
c. Next, the resulting reaction solution is neutralized with an acid, and then separated to separate an oil layer composed of mercaptopropionic acids. Further, mercaptocarboxylic acids dissolved in the aqueous layer are extracted with an organic solvent. Separate the organic solvent layer containing mercaptocarboxylic acids and recover the mercaptocarboxylic acid from the organic solvent layer and / or the oil layer, or extract the neutralized solution with an organic solvent to remove the organic solvent layer containing the mercaptocarboxylic acid. A method for producing ammonia and a mercaptocarboxylic acid represented by the general formula (2), wherein the mercaptocarboxylic acid is obtained by separating and obtaining a mercaptocarboxylic acid from the organic solvent layer.
b.該反応液と無機塩基を混合、加熱し、減圧下で反応系から生成したアンモニアを反応溶液中の溶存濃度が1000ppm以下になるまで反応系外に除去、アンモニアを回収し;
c.次いで、得られた反応液を酸にて中和後、分液してメルカプトプロピオン酸類からなる油層を分離し、さらに、水層中に溶存しているメルカプトカルボン酸類を有機溶媒にて抽出してメルカプトカルボン酸類を含む有機溶媒層を分離し、有機溶媒層、及び、または油層からメルカプトカルボン酸を回収するか、または、中和液を有機溶媒で抽出してメルカプトカルボン酸を含む有機溶媒層を分離し、有機溶媒層からメルカプトカルボン酸を得、d.抽出後の水層から高純度の無機塩水溶液を得ることを特徴とする一般式(2)で示されるメルカプトカルボン酸類の製造方法。a. Reacting an unsaturated nitrile represented by the general formula (1) with an alkali hydrosulfide;
b. Mixing and heating the reaction solution and an inorganic base , removing ammonia generated from the reaction system under reduced pressure until the dissolved concentration in the reaction solution is 1000 ppm or less, and recovering ammonia ;
c. Next, the resulting reaction solution is neutralized with an acid, and then separated to separate an oil layer composed of mercaptopropionic acids. Further, mercaptocarboxylic acids dissolved in the aqueous layer are extracted with an organic solvent. Separate the organic solvent layer containing mercaptocarboxylic acids and recover the mercaptocarboxylic acid from the organic solvent layer and / or the oil layer, or extract the neutralized solution with an organic solvent to remove the organic solvent layer containing the mercaptocarboxylic acid. Separating to obtain mercaptocarboxylic acid from the organic solvent layer; d. A method for producing a mercaptocarboxylic acid represented by the general formula (2), wherein a highly pure inorganic salt aqueous solution is obtained from an aqueous layer after extraction.
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