JPS5857421B2 - Purification method of dimethylformamide - Google Patents

Description

【発明の詳細な説明】 本発明は、含水粗ジメチルホルムアミドを精製する時に
加水分解によって発生している蟻酸を化学的処理によっ
て除去するジメチルホルムアミド（以下り０Ｍ、Ｆ、と
略称する）の精製法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for purifying dimethylformamide (hereinafter abbreviated as 0M, F) in which formic acid generated by hydrolysis during purification of hydrous crude dimethylformamide is removed by chemical treatment. It is related to.

本発明は、ポリウレタン成形物の製造工程である、例え
ばポリウレタン弾性繊維製造工程中から回収される含水
粗り、Ｍ、Ｆ、を再使用可能な純度にして高収率で蒸製
精製するのに寄与する。The present invention contributes to the process of producing polyurethane molded products, for example, by distilling and purifying the water-containing roughness, M, and F, recovered from the process of producing polyurethane elastic fibers, to a reusable purity with a high yield. do.

ＤｌＭ、Ｆ、は加水分解により蟻酸を生成し、一方蟻酸
を含有するり、Ｍ、Ｆ、は、蟻酸自体が分解促進剤とし
ての役割を果すため、精製り、Ｍ、Ｆ。DlM,F produces formic acid through hydrolysis, while M,F contains formic acid, and M,F is purified because formic acid itself plays a role as a decomposition accelerator.

の回収率が低下する。The recovery rate will decrease.

更に、蟻酸を含有する精製り０Ｍ、Ｆ、を溶媒として使
用すると製造物の着色をもたらすのみでなく、重縮合反
応用その他の反応用溶剤として使用するときに所定の重
合度まで上がらないとか、収率が低下して所定の生成物
が得られない等の好ましからざる結果を招（ので、蟻酸
を出来るだけ除去し、系外に排出させることが重要であ
る。Furthermore, when purified 0M, F containing formic acid is used as a solvent, not only does it cause coloring of the product, but also the degree of polymerization does not reach a specified level when used as a solvent for polycondensation reactions and other reactions. It is important to remove as much formic acid as possible and discharge it from the system.

蟻酸を含んだり、Ｍ、Ｆ、は加熱されると無水系ではり
、Ｍ、Ｆ、が分解して次式（１）の如くジメチルアミン
と一酸化炭素を生ずること及び水が共存している時は一
部分が加水分解して次式（２）の如くジメチルアミンと
蟻酸を生成することはよく知られていることである。Contains formic acid, M and F are anhydrous when heated, and M and F decompose to produce dimethylamine and carbon monoxide as shown in the following formula (1), and water coexists. It is well known that at times, a portion of the compound is hydrolyzed to produce dimethylamine and formic acid as shown in the following formula (2).

従来の一般的な蒸製法では蟻酸とり、Ｍ、Ｆ、は分離し
得す、又、共沸蒸製法も困難とされ、この蟻酸問題を解
決するために難溶性の無機塩基性物質で処理する方法、
含水粗り、Ｍ、Ｆ、に不揮発性アルカリを添加しＰＨを
調節する方法、アルカリ金属或はアルカリ士金属のアル
コラード又はそれらのアルコール溶液を添加する方法等
が提案されているが決して満足すべきものではなかった
。In the conventional general steaming method, M and F can be separated by formic acid, and azeotropic steaming is also difficult.To solve this formic acid problem, treatment with a sparingly soluble inorganic basic substance is used. Method,
A method of adjusting the pH by adding a non-volatile alkali to water-containing coarse grains, M and F, and a method of adding an alkali metal or alkali metal alcoholide or an alcohol solution thereof, etc., have been proposed, but none are satisfactory. It wasn't.

本発明方法は、加水分解によって生成する蟻酸を化学的
処理によって不揮発性物質とし、Ｄ、Ｍ Ｆ。In the method of the present invention, formic acid produced by hydrolysis is converted into a non-volatile substance by chemical treatment, and D, MF.

に対するその難溶性を利用して機械的分離濾過操作で蟻
酸濃度を大巾に低下させ、又、機械的分離濾過操作を行
わなくてもそのまま黒部することによって従来法と比較
して蟻酸濃度を著しく低下せしめ得るものであり、本発
明者は鋭意研究の結果再使用可能な高純度で、しかも高
収率で含水粗り０Ｍ、Ｆ、を精製できる本発明方法を完
成したものである。The formic acid concentration can be significantly lowered by mechanical separation and filtration using its low solubility in water, and the formic acid concentration can be significantly reduced compared to conventional methods by forming a black part without mechanical separation and filtration. As a result of intensive research, the present inventor has completed the method of the present invention, which can purify hydrous crude 0M, F with high purity and reusable yield.

即ち、本発明は、含水粗り、Ｍ、Ｆ、を黒部によって精
製するに当り、アミン化合物を中和点迄添加し、含水粗
り、Ｍ、Ｆ、中に含まれる蟻酸を例えば第１アミン類を
用いた場合は、次式（３）の反応に示す如く中和処理す
る方法である。That is, in the present invention, when refining the water-containing grains, M and F, by Kurobe, an amine compound is added to the neutralization point, and the formic acid contained in the water-containing grains, M and F, is purified by, for example, a primary amine. When a compound of the same type is used, the method is to perform a neutralization treatment as shown in the reaction of the following formula (3).

本発明に使用されるアミン化合物としては、（１）イソ
プロピルアミン、ｎ−ブチルアミン、イソブチルアミン
、２−アミノペンタン、オクチルアミンの如き第１アミ
ン類、（２）ジエチルアミン、ジプロピルアミン、ジイ
ソプロピルアミン、メチルイソプロピルアミン、メチル
グロビルアミン、エチルグロビルアミンの如き第２アミ
ン類、（３）エチレンジアミン、エチレンジアミン水和
物、■・２−プロピレンジアミン、ヘキサメチレンジア
ミンの如き脂肪族ジアミン類、（４）■ ・２・３−ト
リアミノプロパン、ｌ−リス（２−アミノエチル）アミ
ン、テトラ（アミノメチル）メタンの如き多価アミン類
、（５）ジエチレントリアミン、トリエチレンテトラミ
ン、テトラエチレンペンタミンの如き線状ポリアミン類
、（６）Ｎ−メチルエチルジアミン、Ｎ・Ｎ′−ジメチ
ルエチレンジアミン、Ｎ−Ｎ’−ジメチルエチレンジア
ミン、Ｎ−エチルエチレンジアミンの如きアルキルエチ
レンジアミン類、（７）トリエチレンイミン、１ ・２
・３−トリメチルトリメチレンイミン ェタノールアミン、１−アミノプロパン−３オールの如
きオキシアルキルアミン類、（９）シクロプロピルアミ
ン、シクロプロピルアミン、シクロプロピルメチルアミ
ン、シクロメチルアミン、１・２−ジアミノシクロヘキ
サンの如き脂環式化合物類、００）アニリン、トルイジ
ンの如き芳香族第１アミン類、（１］）フェニレンジア
ミン、トリレンジアミン、トリアミノベンゼンの如き芳
香族ジアミン類を用いることができる。The amine compounds used in the present invention include (1) primary amines such as isopropylamine, n-butylamine, isobutylamine, 2-aminopentane, and octylamine, (2) diethylamine, dipropylamine, diisopropylamine, Secondary amines such as methylisopropylamine, methylglobylamine, ethylglobylamine, (3) aliphatic diamines such as ethylenediamine, ethylenediamine hydrate, 2-propylenediamine, hexamethylenediamine, (4) ■ Polyvalent amines such as 2,3-triaminopropane, l-lis(2-aminoethyl)amine, and tetra(aminomethyl)methane; (5) wires such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; (6) Alkylethylenediamines such as N-methylethyldiamine, N-N'-dimethylethylenediamine, N-N'-dimethylethylenediamine, N-ethylethylenediamine, (7) Triethyleneimine, 1.2
- Oxyalkylamines such as 3-trimethyltrimethyleneimineethanolamine, 1-aminopropan-3ol, (9) cyclopropylamine, cyclopropylamine, cyclopropylmethylamine, cyclomethylamine, 1,2-diamino Alicyclic compounds such as cyclohexane, (00) aromatic primary amines such as aniline and toluidine, (1) aromatic diamines such as phenylene diamine, tolylene diamine, and triaminobenzene can be used.

尚、上記の如く、本発明においては、蒸溜時に加水分解
によって生成する蟻酸をアミン化合物で処理して不揮発
性物質とするものであり、沸点が３３、０℃であるイソ
プロピルアミンでは蟻酸濃度を約ｏ．ｏ３ｙ′／ｌ：迄
低下せしめることができるが、アミン化合物であっても
沸点が３０℃に満たない例えばモノエチルアミン及びジ
メチルアミン等においては、含水粗り．Ｍ，Ｆ．をこれ
ら低沸点アミン化合物で沖相処理後黒部を行うと蟻酸塩
が溜出し、溜出液中の蟻酸濃度も高く、再使用に不適当
なり．Ｍ．Ｆ．Ｌか得られない。As mentioned above, in the present invention, formic acid produced by hydrolysis during distillation is treated with an amine compound to make it a non-volatile substance, and with isopropylamine, which has a boiling point of 33.0°C, the formic acid concentration is reduced to approximately o. o3y'/l: However, even amine compounds whose boiling point is less than 30°C, such as monoethylamine and dimethylamine, have a water-containing roughness. M,F. If these low-boiling-point amine compounds are used to treat the Oki phase and then perform Kurobe, formate will be distilled out, and the formic acid concentration in the distillate will be high, making it unsuitable for reuse. M. F. I can't get L.

含水粗り．Ｍ．Ｆ．の含水率が低い場合にはアミ５ノ化
合物で蟻酸を中和処理すると反応生成物が白濁等の沈降
物となるので、機械的分離濾過操作により反応生成物を
系外に排出し、その残液の含水粗り．Ｍ．Ｆ，を黒部装
置に供することが出来るが、機械的分離濾過操作をせず
に、そのまま中和処理液を黒部装置に供給することも可
能である。Moisture rough. M. F. If the water content of the formic acid is low, neutralizing formic acid with an amino compound will cause the reaction product to become cloudy and precipitate. Rough water content of liquid. M. F. can be supplied to the Kurobe apparatus, but it is also possible to supply the neutralized liquid as it is to the Kurobe apparatus without mechanical separation and filtration.

又、含水粗り，Ｍ，Ｆ．の含水率が高い場合には、アミ
ノ化合物による中和処理で沈降物は生成しないが、アミ
ン化合物を中和点迄添加したら、そのまま黒部装置に供
給することが出来る。Also, water-containing roughness, M, F. If the moisture content of the water is high, no precipitate will be generated by neutralization with an amino compound, but once the amine compound has been added to the neutralization point, it can be fed to the Kurobe apparatus as is.

尚、先に述べた従来技術である含水粗り．Ｍ，Ｆ。In addition, the water-containing roughening method mentioned above is the conventional technology. M,F.

に不揮発性アルカリを添加しＰＨを調節して黒部し、溜
分中の蟻酸濃度を下げて高純度のり．Ｍ．Ｆ。A non-volatile alkali is added to adjust the pH to form a black part, and the concentration of formic acid in the distillate is lowered to produce high-purity glue. M. F.

を得る方法においては、生成している蟻酸塩によって蒸
溜時に突沸を生じ、これを防止するためには蒸溜操作条
件にかなりの制約を受けることになる。In this method, the formate produced causes bumping during distillation, and in order to prevent this, the distillation operating conditions are subject to considerable restrictions.

又、従来の方法によると蟻酸減少率はいずれも９０％以
下で、蟻酸濃度も１７／ｌ以下にすることが不可能であ
った。Furthermore, according to the conventional methods, the reduction rate of formic acid was less than 90% in all cases, and it was impossible to reduce the formic acid concentration to less than 17/l.

本発明方法によると、含水粗り．Ｍ．Ｆ．を黒部すると
きに含水粗り．Ｍ．Ｆ．中の蟻酸をアミノ化合物との反
応で熱安定性の良好な塩類に変え、高沸点成分中の酸を
押えるので蒸溜時に於ける分解が少な（、しかも突沸現
象を生じることもないので、上記従来法に於ける如く突
沸現象に関連する蒸溜操作条件も何等制約を受けること
な（、ポリウレタン弾性繊維製造用及びその他の用途に
再使用するに充分な含蟻酸濃度の非常に低い良質の精製
り、Ｍ、Ｆ、を高収率で精製して得ることが出来る。According to the method of the present invention, water-containing roughness. M. F. When the black part is removed, it becomes rough due to water content. M. F. The formic acid in the mixture is converted into salts with good thermal stability through the reaction with amino compounds, and the acid in the high-boiling components is suppressed, so there is less decomposition during distillation (and there is no bumping phenomenon, so the above-mentioned conventional The distillation operating conditions related to the bumping phenomenon in the process are not subject to any restrictions (the production of high-quality purified products with a very low concentration of formic acid, which is sufficient for reuse in the production of polyurethane elastic fibers and other uses). M and F can be purified and obtained in high yield.

以下実施例につき説明するが、ＰＨの測定は液を５倍の
黒部水で希釈し測定したものであり、比電導度は東亜電
波工業株式会社製数字式電導度計ＣＭ−２Ａ型にて測定
せる２５℃に於ける値である。Examples will be explained below. PH was measured by diluting the liquid with Kurobe water 5 times, and specific conductivity was measured using a numerical conductivity meter CM-2A manufactured by Toa Denpa Kogyo Co., Ltd. This is the value at 25°C.

又、水分はカールフィッシャー電気滴定装置により、蟻
酸濃度の測定はメチルアルコール溶媒中で過剰のアンモ
ニアにより蟻酸アンモニアとして固定後、アルコール性
の塩酸標準液で滴定測定する通常の方法により分析され
た値である。In addition, water content was measured using a Karl Fischer electrotitration device, and formic acid concentration was determined using the usual method of fixing ammonia formate with excess ammonia in a methyl alcohol solvent and then titrating with an alcoholic hydrochloric acid standard solution. be.

尚、実施例中に記載の画分率（％）は、すべて重量百分
率を意味するものとする。Incidentally, all fraction rates (%) described in the examples mean percentages by weight.

実施例 １ ポリウレタ２浬性糸製造工程より回収された蟻酸１２２
グ／ｌ、水分率１．１４％、比電導度３９００μυ／Ｃ
ＴＬ、 Ｄ、Ｍ、Ｆ、濃度９７．４％の原含水粗り、Ｍ
、Ｆ、に攪拌しながらエチレンジアミンを中和点に達す
る迄添加した。Example 1 Formic acid 122 recovered from the polyurethane yarn manufacturing process
g/l, moisture content 1.14%, specific conductivity 3900 μυ/C
TL, D, M, F, raw water-containing coarse grain with a concentration of 97.4%, M
, F was added with stirring until the neutralization point was reached.

この液中に白色沈澱物が生成したので、これを機械的に
濾過した。A white precipitate was formed in this liquid, so this was mechanically filtered.

この処理によって得られた濾過液を分析した処、比電導
度１０００μυ／Ｃ１′ｒＬで蟻酸濃度は０．４グ／ｌ
と大巾な濃度の減少が認められた。Analysis of the filtrate obtained through this treatment revealed that the specific conductivity was 1000 μυ/C1′rL and the formic acid concentration was 0.4 g/L.
A large decrease in concentration was observed.

この液を３６段の回分式棚段塔で１００ｒｒａｎＨｇ
ａｂｓ 、の減圧下で蒸溜し、８０％を主留として取り
出した。This liquid was heated to 100 rranHg in a 36-stage batch plate column.
ABS was distilled under reduced pressure, and 80% was taken out as the main distillate.

この留出液は比電導度１．２７μυ／ｃＩｒＬ、水分率
０．０９％で、蟻酸濃度は０．０１２ ？／ｌ！と非常
に良好なるり、Ｍ、Ｆ、を回収出来た。This distillate has a specific conductivity of 1.27 μυ/cIrL, a moisture content of 0.09%, and a formic acid concentration of 0.012? /l! We were able to recover M and F in very good condition.

比較のために、上記原含水粗Ｄ 、Ｍ、 Ｆ 、にエチ
レンジアミンを添加せずに同一装置、条件で黒部精製し
た留出液は比電導度８５μυ／ｃｍ、水分率０．６９％
で蟻酸濃度は２．８′？／ｌと再使用には不充分の蟻酸
を含有するり、Ｍ、Ｆ、であった。For comparison, the distillate purified by Kurobe under the same equipment and conditions without adding ethylenediamine to the above-mentioned raw water-containing crude D, M, F has a specific conductivity of 85 μυ/cm and a moisture content of 0.69%.
So the formic acid concentration is 2.8'? /l, which is insufficient for reuse, or M, F.

実施例 ２ 実施例１の原含水粗り、Ｍ、Ｆ、にエチレンジアミンを
中和点に至る迄添加し、液を機械的濾過操作することな
くそのまま３６段回分式棚段塔で１００ｍｍＨｇ ａｂ
ｓ 、の減圧下で蒸溜し８５％を主留として取り出した
。Example 2 Ethylenediamine was added to the raw water-containing rough materials, M and F, of Example 1 until the neutralization point was reached, and the liquid was heated to 100 mmHg ab in a 36-stage batch plate column without mechanical filtration.
It was distilled under reduced pressure of 1.5 s and 85% was taken out as the main distillate.

この留出液を分析すると比電導度１．２９ ｐｕ ７ｃ
ｍ、水分率０．０８％で蟻酸濃度０．０１２グ／ｌと非
常に良質のり、Ｍ、Ｆ、を回収出来た。When this distillate was analyzed, the specific conductivity was 1.29 pu 7c
It was possible to recover very good quality glues, M and F, with a moisture content of 0.08% and a formic acid concentration of 0.012 g/l.

実施例 ３ 比電導度２０１μυ／ｃｍ、水分率５９．３％、Ｄ、Ｍ
、Ｆ、濃度３９．９％で蟻酸濃度５．３３グ／ｌの含水
粗り、Ｍ、Ｆ、にエチレンジアミンを中和点に至る迄添
加し、そのまま蒸溜して８５％の主留を取り出し、留出
液を分析したところ比電導度１、２４ μｖ ７ｃｍ、
水分率０．０７％、蟻酸濃度０、０１１ ？／、ｅ（７
）良質なり１Ｍ、Ｆ、を得た。Example 3 Specific conductivity 201μυ/cm, moisture content 59.3%, D, M
, F, a water-containing crude with a formic acid concentration of 5.33 g/l at a concentration of 39.9%, M, F, was added with ethylenediamine until it reached the neutralization point, and then distilled as it was to remove 85% of the main distillate. When the distillate was analyzed, the specific conductivity was 1.24 μv 7cm,
Moisture content 0.07%, formic acid concentration 0.011? /, e(7
) Good quality 1M, F was obtained.

実施例 ４ 実施例１において用いた原含水粗り、Ｍ、 Ｆ、にヘキ
ザメチレンジアミンを中和点に至る迄添加し、沈澱物を
濾過後この濾液を実施例１におけると同様に３６段回分
式棚段塔で蒸溜したところ、８０％主留で取り出した留
液は比電導度０．５４μυ／ｃｍ、、水分率０．０７％
で蟻酸濃度０．０１−５ ？／１．の良質なり、Ｍ、Ｆ
、であった。Example 4 Hexamethylene diamine was added to the raw water-containing coarse grains, M and F, used in Example 1 until the neutralization point was reached, and after filtering the precipitate, the filtrate was passed through 36 stages in the same manner as in Example 1. When distilled using a batch plate column, the distillate taken out in the 80% main distillate had a specific conductivity of 0.54 μυ/cm and a moisture content of 0.07%.
And formic acid concentration 0.01-5? /1. Good quality, M, F
,Met.

実施例 ５ 実施例１において用いた原含水粗り、Ｍ、Ｆ、にｎ−ブ
チルアミンを中和点に至る迄添加し、実施例２における
と同様に濾過することな（そのまま３６段回分式棚段塔
で１００ｍｍＨｇ ａｂｓ 、の減圧下で蒸溜し８５％
を主留として取り出した。Example 5 N-butylamine was added to the raw water-containing coarse grains, M and F, used in Example 1 until the neutralization point was reached, and the mixture was not filtered in the same manner as in Example 2. Distilled in a plate column under reduced pressure of 100 mmHg abs to 85%
was taken out as the main retainer.

この液を分析したところ比導電度］、５４μυ／ｃｍ、
、水分率０．１０％、蟻酸濃度０．０１２グ／ｌと蟻酸
含有量の少ない良質なり、Ｍ、Ｆ、を回収することが出
来た。Analysis of this liquid revealed that the specific conductivity was 54 μυ/cm.
It was possible to recover M and F, which were of good quality with a moisture content of 0.10% and a formic acid concentration of 0.012 g/l, with a low formic acid content.

実施例 ６ 比電導度６１４０μυ／ｃｒｒＬ、水分率０．８５％、
ＤｏＭ、Ｆ、濃度８５０％、蟻酸濃度１１（１’／ｌの
含水粗り、Ｍ、Ｆ、に中和点に達する迄アニリンを添加
し、生成した沈降物を機械的濾過操作で濾過し、その濾
液を３６段回分式棚段塔で１００ｍｍＨｇ ａｂｓ 、
減圧下で処理し、８５％を主留として取り出した。Example 6 Specific conductivity 6140μυ/crrL, moisture content 0.85%,
DoM, F, concentration 850%, formic acid concentration 11 (1'/l water-containing roughness, M, F, add aniline until the neutralization point is reached, filter the formed precipitate by mechanical filtration operation, The filtrate was heated to 100 mmHg abs in a 36-stage batch plate tower.
It was treated under reduced pressure and 85% was taken out as the main distillate.

この留液は比電導度２．３３μυ／ｃｍ、水分率０．０
４％で蟻酸濃度０．０３４′？／ｌと蟻酸濃度の非常に
少ない良質なり０Ｍ、Ｆ、を得た。This distillate has a specific conductivity of 2.33μυ/cm and a moisture content of 0.0.
Formic acid concentration 0.034' at 4%? A good quality product with a very low formic acid concentration of 0M, F was obtained.

実施例 ７ 比電導度６０５０μυ／ＣｒｒＬ、水分率１．２２％、
Ｄ、Ｍ、Ｆ、濃度８５．５％、蟻酸濃度１１０グ／ｌの
含水粗り、Ｍ、Ｆ、にシクロヘキシルアミンを中和点に
達する迄添加し、沈澱物を濾過し、その濾液を３６段回
分式棚段塔で１００ｍｍＨｇ ａｂｓ 、減圧で蒸溜し
、８５％を主留として取り出した。Example 7 Specific conductivity 6050μυ/CrrL, moisture content 1.22%,
Cyclohexylamine was added to D, M, and F, water-containing coarse grains with a concentration of 85.5% and formic acid concentration of 110 g/l, until the neutralization point was reached, the precipitate was filtered, and the filtrate was Distillation was carried out in a batch plate column under reduced pressure of 100 mmHg abs, and 85% was taken out as the main distillate.

この留出液は比電導度１．７３μυ／ｃｘｔ、水分率０
．０６％で蟻酸濃度０．０２５ ？／ｌ：の良質なり、
Ｍ、Ｆ。This distillate has a specific conductivity of 1.73μυ/cxt and a moisture content of 0.
．． 06% and formic acid concentration 0.025? /l: good quality,
M.F.

を得た。I got it.

比較例 実施例１で用いた含水粗り、Ｍ、Ｆ、液に４０％ＮａＯ
Ｈを中和点迄添加し、沈澱物を濾過せずそのまま３６段
回分式棚段塔で１００ｍｍＨｇ ａｂｓ 、の減圧で蒸
溜し、５０％の主留を取り出し、分析したところ、比電
導度４２０μυ／ｃＩ７′Ｌ、水分率０．２８％、蟻酸
濃度２．７？／ｌと、蟻酸除去率が悪く、再使用不能の
り、Ｍ、Ｆ、Ｌか得られなかった。Comparative Example Hydrous roughness used in Example 1, M, F, 40% NaO in the liquid
H was added to the neutralization point, and the precipitate was distilled without filtration in a 36-stage batch column at a reduced pressure of 100 mmHg abs. 50% of the main distillate was taken out and analyzed, and the specific conductivity was 420 μυ/ cI7'L, moisture content 0.28%, formic acid concentration 2.7? /l, the formic acid removal rate was poor, and glues M, F, and L, which could not be reused, could not be obtained.

参考例 １ 実施例１の原含水粗り、Ｍ、Ｆ、に沸点１６６℃のモノ
エチルアミンを中和点迄添加し、液を機械的濾過操作す
ることなくそのまま３６段回分式棚段塔で１００ｍｍＨ
ｇ ａｂｓ 、の減圧下で蒸溜し８５％を主留として取
り出した。Reference Example 1 Monoethylamine with a boiling point of 166°C was added to the raw water-containing rough materials M and F of Example 1 up to the neutralization point, and the liquid was directly filtered to 100 mmH in a 36-stage batch plate column without mechanical filtration.
It was distilled under reduced pressure of g abs and 85% was taken out as the main distillate.

この留出液を分析した処、比電導度９２．Ｏｐｖ７ｃｍ
、水分率０．０５％、蟻酸０．１２ ？／ｌで蟻酸塩が
０．２４′？／７３と再使用に不充分の蟻酸含有率も高
く蟻酸塩を含有するり、Ｍ、Ｆ、であった。When this distillate was analyzed, the specific conductivity was 92. Opv7cm
, moisture content 0.05%, formic acid 0.12? /l and formate is 0.24'? The formic acid content was high and contained formate, M, F, which was insufficient for reuse at /73.

参考例 ２ 実施例１の原含水粗り、Ｍ、 Ｆ 、に沸点７℃のジメ
チルアミン４０％の水溶液を中和点迄添加し、※参考例
１と同様の主留を取り出し分析した処、比電導度１３５
μυ／ｃＩｎ、水分率０．０８％、蟻酸ｏ、ｉｓｙ／ｚ
で蟻酸塩０．３５’？／ｌ：と再使用に不適のり、Ｍ、
Ｆ、であった。Reference Example 2 A 40% aqueous solution of dimethylamine with a boiling point of 7°C was added to the raw water-containing rough material, M, F, of Example 1 until the neutralization point, and the same main distillate as in Reference Example 1 was taken out and analyzed. Specific conductivity 135
μυ/cIn, moisture content 0.08%, formic acid o, isy/z
And formate 0.35'? /l: and glue unsuitable for reuse, M,
It was F.

尚、上記参考例に記載した蟻酸塩の分析法は下記の通り
である。The analysis method for formate described in the above reference example is as follows.

（１，） １００ｒａｌ矩形ビーカーを直示上皿天秤
にのせ、サンプルＤ６Ｍ、Ｆ、３Ｍ’をとる。(1,) Place a 100 ral rectangular beaker on a direct balance and take samples D6M, F, and 3M'.

（２）エタノール３０ｍ１！を５０ｍ１メスシリンダー
で加える。(2) 30ml of ethanol! Add with a 50ml graduated cylinder.

（３）調整された平沼製滴下制御式電位差滴定装置ＲＡ
ＴＵ型にセットする。(3) Adjusted Hiranuma drip control potentiometric titrator RA
Set in TU type.

（４） ０．０５ｍ１目盛のビューレットより１ ｍ
ｌ（１’） ０．５％ＨＣｌＯ４溶液を正確に添加する
。(4) 1 m from the 0.05 m 1 scale burette
l(1') Add exactly 0.5% HClO4 solution.

この時ＰＨ値を２〜３の範囲内にする。At this time, the pH value is set within the range of 2 to 3.

１ ｍ、ｌの０５％ＨＣｌＯ４を添加してＰＨ３，０以
上であれば更に０．５％ＨＣｌＯ４を添加する。Add 1 m, 1 of 05% HClO4, and if the pH is 3.0 or higher, further add 0.5% HClO4.

（５１Ｎ１５Ｏ−ＮａＯＨで滴定を行い電位（ＰＨ）の
変化曲線を記録する。(Titrate with 51N15O-NaOH and record the potential (PH) change curve.

（６）第１中和点（ＰＫ、 ） Ｖ、 ｍｅとして蟻酸
塩を算出する。(6) Calculate formate as the first neutralization point (PK, ) V, me.

（７）サンプル滴定前にエタノール３０７１１４，０．
５％ＨＣｌＯ４，１ｒｕｅの中和点ｖ。(7) Ethanol 307114,0.0 before sample titration.
Neutralization point v of 5% HClO4, 1rue.

Claims (1)

【特許請求の範囲】[Claims] １ 不純物として蟻酸を含有する含水粗ジメチルホルム
アミドに、常圧で沸点が３０℃以上のアミン化合物を中
和点迄添加し、蒸製することを特徴とするジメチルホル
ムアミドの精製方法。1. A method for purifying dimethylformamide, which comprises adding an amine compound having a boiling point of 30° C. or higher at normal pressure to a neutralization point to hydrous crude dimethylformamide containing formic acid as an impurity, followed by vaporization.