JP3753759B2

JP3753759B2 - Process for producing 5-aminotetrazole

Info

Publication number: JP3753759B2
Application number: JP16821695A
Authority: JP
Inventors: 秀樹小川; 宏明田中; 晋央大西
Original assignee: Toyo Kasei Kogyo Co Ltd
Current assignee: Toyo Kasei Kogyo Co Ltd
Priority date: 1995-06-09
Filing date: 1995-06-09
Publication date: 2006-03-08
Anticipated expiration: 2021-03-08
Also published as: JPH08333354A

Description

【０００１】
【産業上の利用分野】
本発明は樹脂の精密成形、もしくは成形品の軽量化のための発泡、自動車の安全装置としてのエアバッグ用インフレ−タ−もしくは薬剤を拡散するための薫煙剤を目的としたガス発生剤並びに金属のキレ−ト剤或は、テトラゾ−ル誘導体の出発物質として有用な５−アミノテトラゾ−ルの効率的な製造法に関するものである。
【０００２】
【従来の技術】
従来５−アミノテトラゾ−ルの一般的な製造方法としてはグアニジンもしくはその誘導体に亜硝酸を作用させて生成するイミドアジドを酢酸ナトリウム等で加熱閉環させる方法〔（Thiele,Ann.270.54(1892) 〕やジシアンジアミドの炭酸塩にアジ化水素を反応させ亜硝酸で閉環させる方法（N.G.Chernova et al.,C.A.,1981,94,15646e ）等があるが、より一般的な方法はジシアンジアミドとアジ化水素を反応させて合成する方法である。〔Hantzsch and Vagt,Ann.,314,339(1901),Mihina and Harbst,J.Org.Chem.,15,1082(1950),Stolle,Ber.,62,1118(1929)〕
【０００３】
【発明が解決しようとする課題】
５−アミノテトラゾ−ルを安価に効率的に製造する方法は上記ジシアンジアミドとアジ化水素との反応による方法があるが、文献に従って文献通りの方法で合成すると不純物が多量に副生して精製が困難で収率が低いという問題点がある。本発明は副生物が少なく、精製が容易で収率の高い新規な５−アミノテトラゾ−ルの製造法を提供することを目的とするものである。
【０００４】
【課題を解決するための手段】
本発明の第１は水、ジシアンジアミド及びアジ化ナトリウムの溶液を収容した容器を加温し、加温を継続しながら酸を該溶液のｐＨが3.0 以上の酸性になるように添加速度を調節しながら徐々に時間をかけて添加し、更に加温しながら反応系を3.0 以上の酸性のｐＨに保ちながら反応を継続せしめて生成物５−アミノテトラゾ−ルを濾別採取することを特徴とする５−アミノテトラゾ−ルの効率的製造法である。
【０００５】
本発明は精製工程を別に設けるか、結晶の比重差を利用して物理的に分別する方法等が考えられるが、前者は直接のコストアップと収率の低下となり、後者は収率の低下を来し、何れも製造のコストアップの原因となり工業的に好ましいものではない。本発明者らは特別な工程、もしくは特別の処理手段を追加することなく、従来の工程中の操作方法の改良によって不純物低減を計ることを鋭意検討した結果、本発明に到達したもので、本発明者らは原料の一方であるアジ化水素を発生させる際、アジ化ソ−ダに塩酸等の酸を添加し発生させるが、酸の添加速度をコントロ−ルしない場合、反応系が強酸性を呈し、その際、精製に不都合な不純物が生成することを確認した。本発明は、反応で生成する目的物５−アミノテトラゾ−ルが示すpKa 付近の酸度、即ち反応系のｐＨを３以上の酸性、好ましくは3.1 以上の酸性に保ちながら反応させることによって、精製に不都合な不純物の低減を可能にすることに成功したのである。反応系のｐＨが3.0 未満の強酸性では副生成物が多量になり、精製工程を必要とするため収率が著しく低下し、製造費用が高価になるため、本発明には採用することができない。好適な反応系のｐＨは3.1 〜５である。またｐＨ７以上のアルカリ性では反応が進行せず、酸によって上記ｐＨ付近の酸性にする必要がある。
【０００６】
反応の概要を次に示すと、撹拌機付き４つ口フラスコに水、次いでジシアンジアミド、アジ化ソ−ダを撹拌しながら仕込む。その後、反応温度まで昇温し不純物の副生を抑えるために、３６％塩酸を滴下ロ−トから上記の溶液に反応温度を維持しながら撹拌下、４時間を要して滴下する。塩酸を所要量の８０％滴下するまでは反応液のｐＨは3.7 以上を示す。その後、更に反応液のｐＨを酸性状態に保ちながら反応温度で２時間反応させる。反応終了時のｐＨは５−アミノテトラゾ−ル固有のｐＨ＝3.1 を示した。遠心分離によって５−アミノテトラゾ−ルを濾別採取した。
【０００７】
【比較例１】
（従来法による場合）
１Ｌの撹拌機付き４つ口フラスコに水840 ｇを仕込み、次いでジシアンジアミド16.8ｇ、アジ化ソ−ダ27.3ｇを撹拌しながら仕込んだ。３６％塩酸40.5ｇを滴下ロ−トから上の溶液に５０℃以下、撹拌下に１時間を要して滴下した。反応液はｐＨ＝2.4 であった。その後、７５℃まで昇温し、その温度で４時間反応させた。反応系の温度の上昇及び時間の経過とともにｐＨは徐々に上昇し、反応終了時にはｐＨ＝2.8 になった。反応液をＨＰＬＣにて分析した結果、不純物は10.6％であった。室温まで冷却し、通気度1.5(cm/sec）の濾布を用い、遠心分離によって５−アミノテトラゾ−ルを濾別した。このとき濾布の表面に不純物がかなり蓄積した。これら結晶を纏めて減圧下100 ℃で一夜乾燥して、24.0ｇの白色結晶を得た。ＨＰＬＣにて分析した結果、系中の不純物は〔表１〕に示す通りであるが、濾布に付着した細かな結晶中における不純物の量は９０％以上に達した。この従来法では〔表１〕から明らかなように均一な５−アミノテトラゾ−ルを得ることができず、精製工程が必須であった。
【０００８】
【表１】

【０００９】
【実施例１】
１Ｌの撹拌機付き４つ口フラスコに水840 ｇを仕込み、次いでジシアンジアミド16.8ｇ、アジ化ソ−ダ27.3ｇを撹拌しながら仕込んだ。その後、７５℃まで昇温した、次いで不純物の副生を抑えるために、３６％塩酸40.5ｇを滴下ロ−トから上記の得られた溶液に７３〜７７℃で撹拌下、3.5 時間を要して反応させながら滴下した。上記の塩酸量の８０％を滴下するまでは反応液のｐＨは3.7 以上であった。滴下終了時にはｐＨ＝3.0 であった。その後、更に７５℃にて２時間反応させた。反応終了時にはｐＨ＝3.1 になった。反応液をＨＰＬＣにて分析した結果、不純物は0.7 ％であり、従来法に比較して大幅に減少した。室温まで冷却し、遠心分離にて５−アミノテトラゾ−ルを濾別採取した。このとき濾布の表面には不純物は見られなかった。結晶を減圧下100 ℃で一夜乾燥した。27.3ｇの白色結晶を得た。ＨＰＬＣにて分析した結果、不純物は0.0 ％であった。〔実施例１〕の結果を纏めて〔表２〕に示す。
【００１０】
【表２】

【００１１】
【実施例２】
300 mlの撹拌機付き４つ口フラスコに水８４ｇを仕込み、次いでジシアンジアミド21.0ｇ、アジ化ソ−ダ34.1ｇを撹拌しながら仕込んだ。その後、９０℃まで昇温した。次いで３６％塩酸50.7ｇを滴下ロ−トから上記によって得られた溶液に８９〜９１℃で、撹拌下に３時間を要して滴下した。その後、９０℃にて３０分反応させた。反応液のｐＨの挙動は〔実施例１〕とほぼ同じであった。反応液をＨＰＬＣにて分析した結果、不純物は2.5 ％になった。室温まで冷却し、遠心分離によって５−アミノテトラゾ−ルを濾別して採取した。このときも濾布の表面に不純物の蓄積はなかった。これら結晶を纏めて減圧下100 ℃で一夜乾燥して、41.2ｇの白色結晶を得た。ＨＰＬＣにて分析した結果、不純物は0.9 ％であった。
【００１２】
【発明の効果】
以上述べたように、本発明によると、副生成物が少なく、収率の高い精製を容易に行うことができる。したがって、５−アミノテトラゾ−ルを高純度でしかも安価に提供することができるようになり、工業的な寄与は大きい。[0001]
[Industrial application fields]
The present invention relates to a gas generating agent for the purpose of precision molding of a resin, foaming for weight reduction of a molded article, an inflator for an air bag as an automobile safety device, or a smoke agent for diffusing a medicine, and The present invention relates to an efficient process for producing 5-aminotetrazole useful as a starting material for a metal chelating agent or a tetrazole derivative.
[0002]
[Prior art]
Conventionally, as a general method for producing 5-aminotetrazole, imide azide produced by the action of nitrous acid on guanidine or a derivative thereof is heated and closed with sodium acetate or the like [(Thiele, Ann. 270.54 (1892)] or dicyandiamide. There is a method (NGChernova et al., CA, 1981, 94, 15646e) that causes hydrogen azide to react with carbonates of nitrous acid, but a more general method is to react dicyandiamide with hydrogen azide. (Hantzsch and Vagt, Ann., 314, 339 (1901), Mihina and Harbst, J. Org. Chem., 15,1082 (1950), Stolle, Ber., 62, 1118 (1929))
[0003]
[Problems to be solved by the invention]
There is a method of efficiently producing 5-aminotetrazole at low cost by a reaction of the above dicyandiamide and hydrogen azide, but if synthesized according to the literature according to the literature, a large amount of impurities are by-produced and purification is difficult. There is a problem that the yield is low. It is an object of the present invention to provide a novel process for producing 5-aminotetrazole that has few by-products, is easily purified, and has a high yield.
[0004]
[Means for Solving the Problems]
In the first aspect of the present invention, a container containing a solution of water, dicyandiamide and sodium azide is heated, and the rate of acid addition is adjusted so that the pH of the solution becomes 3.0 or more while continuing the heating. The reaction is continued while the reaction system is kept at an acidic pH of 3.0 or higher while further heating, and the product 5-aminotetrazole is collected by filtration. -An efficient method for producing aminotetrazole.
[0005]
In the present invention, a purification process may be provided separately, or a physical separation method using the difference in specific gravity of crystals may be considered, but the former results in a direct cost increase and a decrease in yield, and the latter results in a decrease in yield. However, both cause an increase in manufacturing costs and are not industrially preferable. The inventors of the present invention have reached the present invention as a result of earnestly examining to reduce impurities by improving the operation method in the conventional process without adding a special process or special processing means. The inventors generate hydrogen azide as one of the raw materials by adding an acid such as hydrochloric acid to soda azide. If the rate of acid addition is not controlled, the reaction system is strongly acidic. At that time, it was confirmed that impurities unsuitable for purification were generated. The present invention is inconvenient for purification by reacting while maintaining the acidity in the vicinity of pKa of the target 5-aminotetrazole produced by the reaction, that is, the pH of the reaction system is maintained at 3 or more, preferably 3.1 or more. It has succeeded in enabling reduction of impurities. If the pH of the reaction system is less than 3.0, the amount of by-products becomes large, and a purification step is required, so that the yield is remarkably reduced and the production cost is high, so it cannot be used in the present invention. . The pH of a suitable reaction system is 3.1-5. In addition, when the pH is 7 or higher, the reaction does not proceed, and the acid needs to be acidified around the pH with an acid.
[0006]
The outline of the reaction is as follows. A four-necked flask equipped with a stirrer is charged with water, then dicyandiamide, and sodium azide while stirring. Thereafter, in order to raise the temperature to the reaction temperature and suppress by-product formation of impurities, 36% hydrochloric acid is dropped from the dropping funnel into the above solution while stirring for 4 hours while maintaining the reaction temperature. The pH of the reaction solution is 3.7 or higher until 80% of the required amount of hydrochloric acid is dropped. Thereafter, the reaction solution is further reacted at the reaction temperature for 2 hours while keeping the pH of the reaction solution in an acidic state. The pH at the end of the reaction was pH = 3.1 specific to 5-aminotetrazole. 5-Aminotetrazole was collected by filtration by centrifugation.
[0007]
[Comparative Example 1]
(When using the conventional method)
840 g of water was charged into a 1 L four-necked flask equipped with a stirrer, and then 16.8 g of dicyandiamide and 27.3 g of sodium azide were charged with stirring. 40.5 g of 36% hydrochloric acid was added dropwise from the dropping funnel to the above solution at 50 ° C. or lower with stirring for 1 hour. The reaction solution had pH = 2.4. Then, it heated up to 75 degreeC and made it react at that temperature for 4 hours. The pH gradually increased with increasing temperature of the reaction system and with time, and reached pH = 2.8 at the end of the reaction. As a result of analyzing the reaction solution by HPLC, the impurity was 10.6%. After cooling to room temperature, 5-aminotetrazole was filtered off by centrifugation using a filter cloth having an air permeability of 1.5 (cm / sec). At this time, a considerable amount of impurities accumulated on the surface of the filter cloth. These crystals were combined and dried overnight at 100 ° C. under reduced pressure to obtain 24.0 g of white crystals. As a result of analysis by HPLC, impurities in the system were as shown in [Table 1], but the amount of impurities in fine crystals adhering to the filter cloth reached 90% or more. In this conventional method, as is clear from [Table 1], uniform 5-aminotetrazole could not be obtained, and a purification step was essential.
[0008]
[Table 1]

[0009]
[Example 1]
840 g of water was charged into a 1 L four-necked flask equipped with a stirrer, and then 16.8 g of dicyandiamide and 27.3 g of sodium azide were charged with stirring. Thereafter, the temperature was raised to 75 ° C., and then 40.5 g of 36% hydrochloric acid was added from the dropping funnel to the above-obtained solution at 73 to 77 ° C. with stirring at 73 to 77 ° C. in order to suppress the by-product of impurities. The solution was added dropwise while reacting. The pH of the reaction solution was 3.7 or more until 80% of the amount of hydrochloric acid was dropped. At the end of the addition, pH = 3.0. Thereafter, the mixture was further reacted at 75 ° C. for 2 hours. At the end of the reaction, pH = 3.1. As a result of analyzing the reaction solution by HPLC, the impurity was 0.7%, which was greatly reduced as compared with the conventional method. After cooling to room temperature, 5-aminotetrazole was collected by filtration by centrifugation. At this time, no impurities were found on the surface of the filter cloth. The crystals were dried overnight at 100 ° C. under reduced pressure. 27.3 g of white crystals were obtained. As a result of analysis by HPLC, the impurity was 0.0%. The results of [Example 1] are summarized in [Table 2].
[0010]
[Table 2]

[0011]
[Example 2]
A 300 ml four-necked flask equipped with a stirrer was charged with 84 g of water, and then 21.0 g of dicyandiamide and 34.1 g of sodium azide were charged with stirring. Then, it heated up to 90 degreeC. Next, 50.7 g of 36% hydrochloric acid was added dropwise from the dropping funnel to the solution obtained as described above at 89 to 91 ° C. with stirring for 3 hours. Then, it was made to react at 90 degreeC for 30 minutes. The pH behavior of the reaction solution was almost the same as in [Example 1]. As a result of analyzing the reaction solution by HPLC, impurities became 2.5%. After cooling to room temperature, 5-aminotetrazole was filtered off and collected by centrifugation. At this time, there was no accumulation of impurities on the surface of the filter cloth. These crystals were combined and dried overnight at 100 ° C. under reduced pressure to obtain 41.2 g of white crystals. As a result of analysis by HPLC, the impurity was 0.9%.
[0012]
【The invention's effect】
As described above, according to the present invention, there are few by-products and purification with high yield can be easily performed. Therefore, 5- aminotetrazole can be provided with high purity and at low cost, and the industrial contribution is great.

Claims

Warm a vessel containing a solution of water, dicyandiamide, and sodium azide, and gradually take time while adjusting the rate of addition of the acid so that the pH of the solution becomes 3.0 or higher while continuing the heating. The reaction is continued while the reaction system is kept at an acidic pH of 3.0 or higher while further heating, and the product 5-aminotetrazole is collected by filtration, thereby producing 5-aminotetrazole. Law.