JP3647915B2 - 2-Amino-5-nitrophenylacetic acid and method for producing the same - Google Patents
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Description
【０００１】
【産業上の利用分野】
本発明は、農薬、医薬品等の合成原料として有用な５−ニトロオキシインドールの前駆体となる新規化合物、２−アミノ−５−ニトロフェニル酢酸又はその塩、及びその製造方法に関する。
【０００２】
【従来の技術】
フェニル核置換インドール誘導体には生化学的な効果を持つものが数多く知られており、農薬、医薬品等に利用されている。その際の合成原料となる５−ニトロインドールの製造法として種々のものが提案されている。
【０００３】
例えば５−ニトロインドールの古典的な製法としては、インドリンをＮ−アセチル化あるいはＮ−ベンゾイル化してアミノ基を保護してから５−位をニトロ化後、脱保護して５−ニトロインドリンとし、最後に脱水素化して５−ニトロインドールとする方法（日本化学雑誌、第７８巻、１３７２〜１３７４頁（１９５７年））が知られている。あるいは、２−（２−ハロゲノ−５−ニトロフェニル）エチルアミンを原料として、キノリン銅触媒の存在下、アンモニア水中で加熱閉環して５−ニトロインドリンを製造する方法が特開昭６０−２４３０６６号に記載されている。
また、５−ニトロオキシインドールをジボラン−ＴＨＦで還元して５−ニトロインドールとすることは、シロウェジらの報告（Heinz Sirowej et al., Synthesis, 2, 84(1972)) から容易に推考しうる方法であり、５−ニトロオキシインドールを容易に合成できれば５−ニトロインドールを得る有力な方法といえる。この５−ニトロオキシインドールの製法としては、オキシインドールをニトロ化するサンプターらの方法が知られている（W. C. Sumpter et al., J. Amer. Chem. Soc., 67, 499〜500(1945))。
しかし、インドリンをＮ−アセチル化あるいはＮ−ベンゾイル化してアミノ基を保護してから５−位をニトロ化後、脱保護して５−ニトロインドリンとし、最後に脱水素化して５−ニトロインドールとする方法では、出発原料のインドリンが比較的高価なうえ、多段階の工程を経なければならない。また、特開昭６０−２４３０６６号に記載されている方法では、出発原料の２−（２−ハロゲノ−５−ニトロフェニル）エチルアミンを得るために２−ハロゲノフェニル酢酸のニトロ化、エステル化、酸アミド化、還元という手順を踏まなければならず、工業的に使用するのに好適な原料とは言い難い。
さらに、サンプターらの方法について本発明者らが追試した結果では、５，７−ジニトロ化物の副生が無視できない。そのため高純度の５−ニトロオキシインドールを得るためには再結晶を２、３回繰り返す必要があるという難点がある。
【０００５】
【発明が解決しようとする課題】
従って、入手の容易な出発物質から少ない工程で合成でき、しかも容易に閉環して５−ニトロインドールまたは５−ニトロオキシインドールとなる新しい前駆体の開発が望まれていた。
【０００６】
【課題を解決するための手段】
上記の課題に鑑み本発明者らが鋭意研究した結果、高純度での入手が比較的容易な２−ハロゲノ−５−ニトロフェニル酢酸の２位をアミノ基に置換して得られる新規化合物、２−アミノ−５−ニトロフェニル酢酸が、容易に閉環して５−ニトロオキシインドールを生成し、５−ニトロオキシインドールの前駆体となることを見い出し、この知見に基づき本発明をなすに至った。
すなわち本発明は、
（１）下記式（Ｉ）で表わされる２−アミノ−５−ニトロフェニル酢酸又はその塩、
【０００７】
【化３】
（式中、Ｍ1 は水素原子、アンモニウム基もしくはアルカリ金属を表わす。）
（２）下記式（II）で表わされる２−ハロゲノ−５−ニトロフェニル酢酸又はその塩（以下、発明の一般的説明では単に２−ハロゲノ−５−ニトロフェニル酢酸という）に触媒の存在下アンモニアを反応させることを特徴とする、（１）項記載の２−アミノ−５−ニトロフェニル酢酸又はその塩（以下、発明の一般的説明では単に２−アミノ−５−ニトロフェニル酢酸という）の製造方法、
【０００９】
【化４】
（式中、Ｘはハロゲン原子を表わし、Ｍ2 は水素原子、アンモニウム基もしくはアルカリ金属を表わす。）
（３）触媒が銅塩である（２）項記載の２−アミノ−５−ニトロフェニル酢酸の製造方法、及び
（４）アンモニア水中で加熱することによりアミノ化を行う（２）項記載の２−アミノ−５−ニトロフェニル酢酸の製造方法
を提供するものである。
【００１１】
本発明において２−アミノ−５−ニトロフェニル酢酸の製造方法において出発物質として用いる２−ハロゲノ−５−ニトロフェニル酢酸は、前記式（II）で示した構造の化合物で、具体的には２−クロロ−５−ニトロフェニル酢酸、２−ブロモ−５−ニトロフェニル酢酸等が挙げられ、好ましくはクロル体である。この化合物は、遊離酸、アンモニウム塩、あるいはナトリウム、カリウムなどのアルカリ金属塩のいずれでもよく、好ましくは遊離酸である。
【００１２】
本発明におけるアミノ化の反応は、耐圧製の反応容器を用い、好ましくは反応溶媒も兼ねたアンモニア水中で行う。アンモニア水の濃度は好ましくは１０〜５０ｗｔ％、より好ましくは２０〜３５ｗｔ％である。アンモニアの濃度が低すぎると加水分解生成物である２−ヒドロキシ−５−ニトロフェニル酢酸の副生する割合が増えるうえ、反応系内のｐＨの低下が進んで反応容器の耐食性に悪影響を与える。また、アンモニアの濃度が高すぎる場合には、反応時の圧力が極めて高くなるため反応装置の仕様に制約が生じたり、アンモニア水の回収、再使用に不利になったりすることがある。
アンモニアの使用量は前記式（II）で示される２−ハロゲノ−５−ニトロフェニル酢酸１モルに対して４〜４０倍モル、好ましくは１０〜３０倍モルである。アンモニアの使用量が少なすぎると撹拌が困難になり、装置の腐食が大きくなることがある。また多すぎても反応結果は向上せず、生産効率が低下する。
【００１３】
本発明のアミノ化反応の反応温度は７０〜１３０℃、好ましくは８０〜１１０℃、より好ましくは９０〜１００℃である。反応温度が低すぎると反応速度が遅くなり、高すぎると着色性不純物の副生量が増加するうえ、装置に耐食性や耐圧性についての制約が生じることがある。
反応圧力はアンモニア水の濃度や反応温度等に依存するが、通常４〜７ｋｇ／ｃｍ2 Ｇである。また、反応時間は好ましくは１０〜３５時間、より好ましくは１６〜２６時間である。
【００１４】
本発明の２−アミノ−５−ニトロフェニル酢酸の製造方法の触媒としては銅塩を用いることができ、具体的には塩化第一銅、臭化第一銅、ヨウ化第一銅、酸化第一銅などの１価の銅塩、あるいは塩化第二銅、水酸化第二銅、酸化第二銅、硫酸銅などの２価の銅塩を挙げることができ、反応活性、選択性などから塩化第一銅、臭化第一銅、ヨウ化第一銅、酸化第一銅などの１価の銅塩がより好ましい。触媒の使用量は、式（II）で示される２−ハロゲノ−５−ニトロフェニル酢酸１モルに対して、１価および２価の銅塩とも銅原子に換算して０．００１〜１．０グラム原子、好ましくは０．０５〜０．３グラム原子である。触媒量が少なすぎると反応速度が遅くなり、未反応原料が多く残る。また多すぎると後処理での触媒の除去操作が複雑になるため好ましくない。
【００１５】
以上のような反応により、出発物質の転化率は９７〜１００％に到達する。
【００１６】
反応終了後、過剰のアンモニアを蒸留等により回収すると、残った生成物として２−アミノ−５−ニトロフェニル酢酸が７５〜８５％の収率で得られる。ここには閉環生成物の５−ニトロオキシインドールは含まれない。この生成物を４０℃以下、好ましくは３０℃以下の温度に保ちながら、塩酸、硫酸などの鉱酸でｐＨ３〜４にすることにより結晶化する。これを濾過、水洗、乾燥することにより２−アミノ−５−ニトロフェニル酢酸を単離して得ることができる。
【００１７】
本発明の２−アミノ−５−ニトロフェニル酢酸は、適当な溶媒に溶解して酸触媒の存在下で加熱すると容易に閉環して５−ニトロオキシインドールとなる新規化合物である。前記式（Ｉ）で示したように、本発明の化合物は、遊離酸、アンモニウム塩、あるいはナトリウム、カリウムなどのアルカリ金属塩のいずれでもよく、好ましくは遊離酸である。
【００１８】
【発明の効果】
本発明によれば、高純度での入手が比較的容易な２−ハロゲノ−５−ニトロフェニル酢酸を出発原料として、２−アミノ−５−ニトロフェニル酢酸を得ることができる。この２−アミノ−５−ニトロフェニル酢酸は容易に閉環反応して高収率で５−ニトロオキシインドールを与えるという優れた作用効果を奏する。
【００１９】
【実施例】
次に、本発明を実施例に基づいてさらに詳細に説明する。
参考例１（２−クロロ−５−ニトロフェニル酢酸の合成）
５００ｍｌの４ツ口フラスコに２−クロロフェニル酢酸８５．３ｇ（０．５０モル）及び濃硫酸４００ｇを加え、撹拌溶解した。撹拌しながら発煙硝酸（比重１．５）３３．５ｇ（０．５３モル）を−５〜０℃にて１時間かけて滴下後、同温度で３０分間撹拌し、氷５００ｇ中に投入して結晶化した。得られた結晶を吸引濾過して水３００ｇで洗浄後、水５００ｇに投入して分散、スラリー化させた。この結晶を再度濾過、水洗、乾燥すると、２−クロロ−５−ニトロフェニル酢酸が白色粉末として１０５ｇ（収率９７．４％）得られた。
この粉末の少量をトルエンに溶解し、メタノール及びトリメチルシリルジアゾメタン試薬を加えてメチルエステル化し、キャピラリーガスクロマトグラフィーで分析した結果、純度は９８．４％であった。
ｍ．ｐ． １７０．３℃
【００２０】
実施例１（２−アミノ−５−ニトロフェニル酢酸の合成）
５００ｍｌのステンレス製オートクレーブに参考例１で合成した２−クロロ−５−ニトロフェニル酢酸３７．４ｇ（０．１７モル）、２５％アンモニア水３００ｇ（４．４１モル）及び触媒として塩化第一銅３．３ｇ（０．０３３モル）を加えて密閉した。窒素で内部の空気をパージした後、９５℃で２４時間撹拌し反応させた。反応時の内圧は４．９〜４．６ｋｇ／ｃｍ2 Ｇであった。
反応後、３０℃まで冷却し、窒素シール下でアミノ化反応混合物を取り出した。反応混合物を高速液体クロマトグラフィーで分析したところ、２−クロロ−５−ニトロフェニル酢酸の転化率は９９．７％であり、２−アミノ−５−ニトロフェニル酢酸が８２．１％の収率で生成していた。２−アミノ−５−ニトロフェニル酢酸の閉環生成物である５−ニトロオキシインドールは検出されなかった。反応混合物を１００℃まで加熱昇温して過剰のアンモニアを除去し、室温まで冷却後、３５％塩酸をｐＨが３〜４になるまで４０℃以下で加えて結晶を析出させた。この結晶を吸引濾過、水洗、乾燥すると、純度７８．５％の粗２−アミノ−５−ニトロフェニル酢酸が３４．２ｇ（純分収率８０．５％）得られた。これをメタノール２５０ｍｌに溶解して不溶分を濾別後、濾液を加熱して約３分の１の重量までメタノールを濃縮し再結晶すると、黄色結晶で純度９８．２％の２−アミノ−５−ニトロフェニル酢酸２０．６ｇ（収率６１％）が得られた。
参考例２（５−ニトロオキシインドールの合成）
実施例１で得られた２−アミノ−５−ニトロフェニル酢酸９．９ｇにアセトニトリル２００ｇ、水２０ｇ及び５０％硫酸０．８ｇを加えて、窒素気流下、６０℃で１時間加熱撹拌した。反応混合物をサンプリングして高速液体クロマトグラフィーで分析したところ、λmax ３７７ｎｍの２−アミノ−５−ニトロフェニル酢酸のピークが消滅し、λmax ３３０ｎｍの５−ニトロオキシインドールに変化していた。反応混合物を約４分の１の量まで減圧濃縮した後、室温に冷却した。析出した結晶を濾過、水洗、乾燥すると、褐色粉末の５−ニトロオキシインドール７．２ｇ（収率８２％）が得られた。
[Industrial application fields]
The present invention relates to a novel compound, 2-amino-5-nitrophenylacetic acid or a salt thereof, which is a precursor of 5-nitrooxindole useful as a synthetic raw material for agricultural chemicals and pharmaceuticals, and a method for producing the same.
[0002]
[Prior art]
Many phenyl nucleus-substituted indole derivatives are known to have biochemical effects and are used in agricultural chemicals and pharmaceuticals. Various methods have been proposed for producing 5-nitroindole as a raw material for synthesis.
[0003]
For example, as a classic production method of 5-nitroindole, indoline is N-acetylated or N-benzoylated to protect the amino group, then nitrated at the 5-position, and deprotected to 5-nitroindoline. Finally, a method of dehydrogenating to 5-nitroindole (Nippon Kagaku Kagaku, Vol. 78, pages 1372 to 1374 (1957)) is known. Alternatively, JP-A-60-243066 discloses a method for producing 5-nitroindoline by using 2- (2-halogeno-5-nitrophenyl) ethylamine as a raw material to heat and close in ammonia water in the presence of a quinoline copper catalyst. Has been described.
Moreover, reduction of 5-nitrooxindole with diborane-THF to 5-nitroindole can be easily inferred from a report by Shirowage et al. (Heinz Sirowej et al., Synthesis, 2 , 84 (1972)). This method is a powerful method for obtaining 5-nitroindole if 5-nitrooxindole can be easily synthesized. As a method for producing this 5-nitrooxindole, Sumpter et al.'S method for nitrating oxindole is known (WC Sumpter et al., J. Amer. Chem. Soc., 67 , 499-500 (1945)). ).
However, indoline is N-acetylated or N-benzoylated to protect the amino group, then nitrated at the 5-position, then deprotected to 5-nitroindoline, and finally dehydrogenated to 5-nitroindole and In this method, the starting material, indoline, is relatively expensive and requires a multi-step process. In addition, in the method described in JP-A-60-243066, 2-halogenophenylacetic acid is nitrated, esterified and acidized to obtain 2- (2-halogeno-5-nitrophenyl) ethylamine as a starting material. The procedure of amidation and reduction must be followed, and it is difficult to say that the raw material is suitable for industrial use.
Furthermore, by the results of the present inventors' additional trial on the method of Sumpter et al., The by-product of 5,7-dinitrated product cannot be ignored. Therefore, in order to obtain high-purity 5-nitrooxindole, there is a drawback that it is necessary to repeat recrystallization a few times.
[0005]
[Problems to be solved by the invention]
Accordingly, it has been desired to develop a new precursor that can be synthesized from a readily available starting material with a small number of steps, and can be easily closed to give 5-nitroindole or 5-nitrooxindole.
[0006]
[Means for Solving the Problems]
As a result of intensive studies by the present inventors in view of the above problems, a novel compound obtained by substituting the amino group for 2-position of 2-halogeno-5-nitrophenylacetic acid, which is relatively easily available in high purity, 2 -Amino-5-nitrophenylacetic acid was found to be easily cyclized to form 5-nitrooxyindole to be a precursor of 5-nitrooxyindole, and the present invention was made based on this finding.
That is, the present invention
(1) 2-amino-5-nitrophenylacetic acid represented by the following formula (I) or a salt thereof,
[0007]
[Chemical 3]
(In the formula, M 1 represents a hydrogen atom, an ammonium group or an alkali metal.)
(2) 2-halogeno-5-nitrophenylacetic acid represented by the following formula (II) or a salt thereof (hereinafter simply referred to as 2-halogeno-5-nitrophenylacetic acid in the general description of the invention) in the presence of a catalyst; Of 2-amino-5-nitrophenylacetic acid or a salt thereof according to item (1) (hereinafter simply referred to as 2-amino-5-nitrophenylacetic acid in the general description of the invention), Method,
[0009]
[Formula 4]
(In the formula, X represents a halogen atom, and M 2 represents a hydrogen atom, an ammonium group or an alkali metal.)
(3) The method for producing 2-amino-5-nitrophenylacetic acid as described in (2), wherein the catalyst is a copper salt, and (4) performing amination by heating in ammonia water. A method for producing amino-5-nitrophenylacetic acid is provided.
[0011]
In the present invention, 2-halogeno-5-nitrophenylacetic acid used as a starting material in the process for producing 2-amino-5-nitrophenylacetic acid is a compound having the structure represented by the formula (II), specifically 2- Examples include chloro-5-nitrophenylacetic acid, 2-bromo-5-nitrophenylacetic acid, and the like, and a chloro compound is preferred. This compound may be a free acid, an ammonium salt, or an alkali metal salt such as sodium or potassium, and is preferably a free acid.
[0012]
The amination reaction in the present invention is carried out using a pressure-resistant reaction vessel, preferably in ammonia water that also serves as a reaction solvent. The concentration of ammonia water is preferably 10 to 50 wt%, more preferably 20 to 35 wt%. If the ammonia concentration is too low, the proportion of 2-hydroxy-5-nitrophenylacetic acid, which is a hydrolysis product, increases as a by-product, and the pH in the reaction system decreases, which adversely affects the corrosion resistance of the reaction vessel. Moreover, when the concentration of ammonia is too high, the pressure during the reaction becomes extremely high, which may restrict the specifications of the reaction apparatus and may be disadvantageous for the recovery and reuse of aqueous ammonia.
The amount of ammonia used is 4 to 40 times mol, preferably 10 to 30 times mol for 1 mol of 2-halogeno-5-nitrophenylacetic acid represented by the formula (II). If the amount of ammonia used is too small, stirring becomes difficult and corrosion of the device may increase. If the amount is too large, the reaction result is not improved and the production efficiency is lowered.
[0013]
The reaction temperature of the amination reaction of the present invention is 70 to 130 ° C, preferably 80 to 110 ° C, more preferably 90 to 100 ° C. If the reaction temperature is too low, the reaction rate will be slow, and if it is too high, the amount of by-produced coloring impurities will increase, and the apparatus may be restricted in terms of corrosion resistance and pressure resistance.
The reaction pressure depends on the concentration of ammonia water, the reaction temperature, etc., but is usually 4-7 kg / cm 2 G. The reaction time is preferably 10 to 35 hours, more preferably 16 to 26 hours.
[0014]
A copper salt can be used as a catalyst for the production method of 2-amino-5-nitrophenylacetic acid according to the present invention. Specifically, cuprous chloride, cuprous bromide, cuprous iodide, oxidized oxide Monovalent copper salts such as monocopper, or divalent copper salts such as cupric chloride, cupric hydroxide, cupric oxide, and copper sulfate can be cited. From the viewpoint of reaction activity, selectivity, etc. Monovalent copper salts such as cuprous, cuprous bromide, cuprous iodide and cuprous oxide are more preferred. The amount of the catalyst used is 0.001 to 1.0 in terms of a copper atom for both monovalent and divalent copper salts with respect to 1 mol of 2-halogeno-5-nitrophenylacetic acid represented by the formula (II). Gram atoms, preferably 0.05 to 0.3 gram atoms. If the amount of catalyst is too small, the reaction rate becomes slow and a large amount of unreacted raw material remains. On the other hand, if the amount is too large, the catalyst removal operation in the post-treatment is complicated, which is not preferable.
[0015]
By the reaction as described above, the conversion rate of the starting material reaches 97 to 100%.
[0016]
After completion of the reaction, excess ammonia is recovered by distillation or the like, and 2-amino-5-nitrophenylacetic acid is obtained in a yield of 75 to 85% as the remaining product. This does not include the ring-closing product 5-nitrooxindole. The product is crystallized by adjusting the pH to 3 to 4 with a mineral acid such as hydrochloric acid or sulfuric acid while maintaining the temperature at 40 ° C. or lower, preferably 30 ° C. or lower. It can be obtained by isolating 2-amino-5-nitrophenylacetic acid by filtration, washing with water and drying.
[0017]
The 2-amino-5-nitrophenylacetic acid of the present invention is a novel compound that is easily ring-closed to 5-nitrooxindole when dissolved in an appropriate solvent and heated in the presence of an acid catalyst. As shown by the formula (I), the compound of the present invention may be any of free acid, ammonium salt, or alkali metal salt such as sodium and potassium, preferably free acid.
[0018]
【The invention's effect】
According to the present invention, 2-amino-5-nitrophenylacetic acid can be obtained using 2-halogeno-5-nitrophenylacetic acid, which is relatively easy to obtain in high purity, as a starting material. This 2-amino-5-nitrophenylacetic acid has an excellent effect of easily ring-closing to give 5-nitrooxindole in a high yield.
[0019]
【Example】
Next, the present invention will be described in more detail based on examples.
Reference Example 1 (Synthesis of 2-chloro-5-nitrophenylacetic acid)
To a 500 ml four-necked flask, 85.3 g (0.50 mol) of 2-chlorophenylacetic acid and 400 g of concentrated sulfuric acid were added and dissolved by stirring. While stirring, 33.5 g (0.53 mol) of fuming nitric acid (specific gravity 1.5) was added dropwise at −5 to 0 ° C. over 1 hour, stirred at the same temperature for 30 minutes, and poured into 500 g of ice. Crystallized. The obtained crystals were filtered by suction and washed with 300 g of water, and then poured into 500 g of water to be dispersed and slurried. The crystals were filtered again, washed with water and dried to obtain 105 g (yield 97.4%) of 2-chloro-5-nitrophenylacetic acid as a white powder.
A small amount of this powder was dissolved in toluene, methanol and trimethylsilyldiazomethane reagent were added to form a methyl ester, and the result was analyzed by capillary gas chromatography. As a result, the purity was 98.4%.
m. p. 170.3 ° C
[0020]
Example 1 (Synthesis of 2-amino-5-nitrophenylacetic acid)
In a 500 ml stainless steel autoclave, 37.4 g (0.17 mol) of 2-chloro-5-nitrophenylacetic acid synthesized in Reference Example 1, 300 g (4.41 mol) of 25% aqueous ammonia and cuprous chloride 3 as a catalyst .3 g (0.033 mol) was added and sealed. After purging the internal air with nitrogen, the reaction was stirred at 95 ° C. for 24 hours. The internal pressure during the reaction was 4.9 to 4.6 kg / cm 2 G.
After the reaction, the reaction mixture was cooled to 30 ° C., and the amination reaction mixture was taken out under a nitrogen seal. The reaction mixture was analyzed by high performance liquid chromatography. The conversion of 2-chloro-5-nitrophenylacetic acid was 99.7%, and 2-amino-5-nitrophenylacetic acid was obtained in a yield of 82.1%. It was generated. 5-nitrooxindole, a ring-closing product of 2-amino-5-nitrophenylacetic acid, was not detected. The reaction mixture was heated to 100 ° C. to remove excess ammonia, cooled to room temperature, and then 35% hydrochloric acid was added at 40 ° C. or lower until the pH reached 3-4 to precipitate crystals. The crystals were suction filtered, washed with water, and dried to obtain 34.2 g (pure yield 80.5%) of crude 2-amino-5-nitrophenylacetic acid having a purity of 78.5%. This was dissolved in 250 ml of methanol and the insoluble matter was filtered off. The filtrate was heated to concentrate methanol to a weight of about one third, and recrystallized to give 2-amino-5 having a purity of 98.2% as yellow crystals. -20.6 g (61% yield) of nitrophenylacetic acid was obtained.
Reference Example 2 (Synthesis of 5-nitrooxindole)
200 g of acetonitrile, 20 g of water and 0.8 g of 50% sulfuric acid were added to 9.9 g of 2-amino-5-nitrophenylacetic acid obtained in Example 1, and the mixture was heated and stirred at 60 ° C. for 1 hour in a nitrogen stream. When the reaction mixture was sampled and analyzed by high performance liquid chromatography, the peak of 2-amino-5-nitrophenylacetic acid at λ max 377 nm disappeared and changed to 5-nitrooxindole at λ max 330 nm. The reaction mixture was concentrated under reduced pressure to about one-quarter amount and then cooled to room temperature. The precipitated crystal was filtered, washed with water, and dried to obtain 7.2 g (yield 82%) of brown powder of 5-nitrooxindole.
Claims (4)
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| JP29365394A JP3647915B2 (en) | 1994-11-04 | 1994-11-04 | 2-Amino-5-nitrophenylacetic acid and method for producing the same |
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| JP29365394A JP3647915B2 (en) | 1994-11-04 | 1994-11-04 | 2-Amino-5-nitrophenylacetic acid and method for producing the same |
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