JPH0445782B2

JPH0445782B2 -

Info

Publication number: JPH0445782B2
Application number: JP58191260A
Authority: JP
Inventors: Shinichi Kuwata; Hiromasa Kato; Mitsumasa Ono
Original assignee: Mitsubishi Chemical Industries Ltd
Current assignee: Mitsubishi Chemical Corp
Priority date: 1983-10-13
Filing date: 1983-10-13
Publication date: 1992-07-27
Also published as: JPS6082860A

Description

[Detailed description of the invention]

本発明は水分測定用滴定試薬に関するものであ
る。従来、溶液中の水分の測定は原理的にKarl
Fischerによつて見つけられたカール・フイツシ
ヤー反応を利用して行なわれてきた。そして、二酸化硫黄、ヨウ素及びピリジンを主
成分として含み、それらをメタノール等の溶媒に
溶かしたもの等がカール・フイシヤー試薬として
実用化されており、この場合のカール・フイシヤ
ー試薬と水との反応は次式の如く進行する。 SO₂＋I₂＋H₂O＋3C₅H₅N →2C₅H₅N・HI＋C₅H₅N・SO₃ …(1) C₅H₅N・SO₃＋CH₃OH →C₅H₅N・HSO₄CH₃ …(2) また、水分測定の手法としては上記のような、
カール・フイシヤー試薬をそのまま水と定量的に
反応させて、水分量を測定する容量滴定法の他に
上記カール・フイシヤー反応に必要なヨウ素をヨ
ウ素化物イオンの電解酸化により内部的に生させ
て水分を測定する電量滴定法がある。また上記した容量滴定法による水分測定に用い
るカール・フイシヤー試薬には、二酸化硫黄、ヨ
ウ素及びピリジン等の各成分を単一の溶液中に含
有させた一液型試薬の他に、ヨウ素を適当な溶媒
に溶解したものを滴定剤とし、二酸化硫黄及びピ
リジン等を適当な溶媒に溶解したものを溶剤とし
て用いる二液型試薬がある。特に、二液型試薬は、測定の妨害が少なく、ま
た測定時間が短かい利点がある。最近、ピリジンの特異な臭いをきらつて電量滴
定試薬及び容量滴定試薬に於てピリジンの代りに
イミダゾールやジエタノールアミンなどを用いた
滴定試薬が提案され、ピリジン以外のアミンを用
いた水分測定試薬の可能性が示唆された（特開昭
56−137250号公報参照）。しかしながら、これら
はピリジンより反応性に富むため水分測定の精度
が低下したり測定が不能であつたりする場合があ
りその改良が望まれていた。本発明者らは以上の事実に基づき従来操作上不
便をきたしていたその特有な臭いのしないカー
ル・フイシヤー試薬を見いだすべく鋭意検討した
結果、本発明に到達した。即ち、本発明は、ヨウ素又はヨウ素化物、二酸
化硫黄並びに下記、(イ)及び(ロ)から成る群から選ば
れる少なくとも１種のアミンを含有してなる水分
測定用滴定試薬 (イ) 一般式 The present invention relates to a titration reagent for measuring moisture. Traditionally, the principle of measuring water in solutions is based on Karl
It has been carried out using the Karl-Fitscher reaction discovered by Robert Fischer. A substance containing sulfur dioxide, iodine, and pyridine as main components and dissolved in a solvent such as methanol has been put into practical use as a Karl-Fuchscher reagent. The process proceeds as shown in the following equation. SO ₂ +I ₂ +H ₂ O+3C ₅ H ₅ N →2C ₅ H ₅ N・HI+C ₅ H ₅ N・SO ₃ …(1) C ₅ H ₅ N・SO ₃ +CH ₃ OH →C ₅ H ₅ N・HSO ₄ CH ₃ …(2) In addition, as a method for measuring moisture, the above method is used.
In addition to the volumetric titration method in which the Karl-Fuchsier reagent is quantitatively reacted with water as it is to measure the water content, the iodine required for the above-mentioned Karl-Fuchsier reaction is generated internally by electrolytic oxidation of iodide ions to measure the water content. There is a coulometric titration method that measures . In addition, the Karl-Fuchscher reagent used for water measurement by the above-mentioned volumetric titration method is a one-component reagent containing components such as sulfur dioxide, iodine, and pyridine in a single solution, as well as an appropriate amount of iodine. There is a two-component reagent that uses a titrant dissolved in a solvent as a titrant and a solvent in which sulfur dioxide, pyridine, etc. are dissolved in an appropriate solvent. In particular, two-component reagents have the advantage of causing less interference with measurements and shortening the measurement time. Recently, titration reagents using imidazole or diethanolamine instead of pyridine have been proposed in coulometric and volumetric titration reagents due to the unique odor of pyridine, and there is a possibility of water measurement reagents using amines other than pyridine. was suggested (JP-A-Sho
56-137250). However, since these are more reactive than pyridine, the accuracy of moisture measurement may be lowered or measurement may be impossible, and an improvement has been desired. Based on the above-mentioned facts, the present inventors conducted intensive studies to find a Karl-Fuchscher reagent that does not have the characteristic odor that has conventionally caused operational inconvenience, and as a result, the present invention was achieved. That is, the present invention provides a titration reagent for measuring moisture content (a) containing iodine or an iodide, sulfur dioxide, and at least one amine selected from the group consisting of (a) and (b) below.

【式】（式中、R¹及びR₂ は水素原子、アルキル基、隣接するＮ原子と共
に閉環していてもよいアルキレン基、ピリジル
基又はピロリジニル基である）で表わされるア
ミン。 (ロ) 一般式An amine represented by the formula: (wherein R ¹ and R ₂ are a hydrogen atom, an alkyl group, an alkylene group which may be ring-closed together with the adjacent N atom, a pyridyl group, or a pyrrolidinyl group). (b) General formula

【式】（式中、R³及びR⁴ は、水素原子、水酸基で置換されていてもよい
アルキル基、又はCnH₂nOR（ｎ＝１〜３、Ｒ
はアルキル基を表わす）で示されるアルコキシ
アルキル基であり、R³及びR⁴が同時に水素原
子であることはない）で表わされるアミン。及び、二酸化硫黄及びアミンを含有する溶液Ａ並
びにヨウ素を含有する溶液Ｂから成る滴定試薬に
おいて、該溶液Ａ中のアミンが下記(イ)及び(ロ)から
成る群から選ばれる少なくとも１種のアミンを含
有してなる水分測定用滴定試薬 (イ) 一般式[Formula] (wherein R ³ and R ⁴ are a hydrogen atom, an alkyl group optionally substituted with a hydroxyl group, or CnH ₂ nOR (n=1 to 3, R
represents an alkyl group), and R ³ and R ⁴ are not hydrogen atoms at the same time). and a titration reagent consisting of a solution A containing sulfur dioxide and an amine and a solution B containing iodine, in which the amine in the solution A is at least one amine selected from the group consisting of the following (a) and (b): Titration reagent for moisture measurement containing (a) General formula

【式】（式中、R³及びR⁴ は水素原子、水酸基で置換されていてもよいア
ルキル基、又はCnH₂nOR（ｎ＝１〜３、Ｒは
アルキル基を表わす）で示されるアルコキシア
ルキル基であり、R³及びR⁴が同時に水素原子
であることはない）で表わされるアミン。を要旨とするものである。以下に、本発明につき、更に詳細に説明する。本発明の水分測定用滴定試薬は、容量滴定、電
量滴定のいずれの滴定試薬としても好適に用いる
ことができ、また一液型試薬としてだけでなく、
二液型試薬としても使用できるものである。本発明の水分測定用滴定試薬はヨウ素又はヨウ
素化物、二酸化硫黄及び特定のアミンを含有する
ことが必要である。本発明の水分測定用滴定試薬を一液型試薬とし
て用いる場合には、ヨウ素成分として、ヨウ素又
はヨウ素化物を、また、二液型試薬として用いる
場合にはヨウ素を含有させる。従つて、通常はヨウ素（単体）が用いられる
が、電量滴定法による水分測定の場合には試薬調
製時にヨウ素（単体）の形態で添加したとして
も、水分測定する試料を注入する直前に全てヨウ
素化物イオンとして存在させるので、滴定方法に
よつてヨウ素又はヨウ素化物を適宜用いればよ
い。ヨウ素化物としては、例えば、テトラブチルア
ンモニウムアイオダイド等が挙げられる。ヨウ素又はヨウ素化物の濃度は、ヨウ素化物イ
オンとして0.01〜0.4mol／、好ましくは0.03〜
0.10mol／の範囲である。一般に、電量滴定試
薬におい、ヨウ素化物イオンの濃度が高すぎると
反応速度が遅くなり、また、低すぎると電流効率
が低くなる傾向があるので、ヨウ素化物は、この
濃度範囲で含有させる。次に、二酸化硫黄は、反応を促進する作用を有
し、過剰に存在させることも可能である。しかし
ながら通常は0.3〜2mol／の範囲、特に0.6〜
1.5mol／の範囲で含有させるのが好ましい。また、本発明の水分測定用滴定試薬は以下に述
べる特定のアミンを含有する。即ち、下記(イ)、(ロ)、(ハ)及び(ニ)から成る群から
選
ばれる少なくとも１種のアミンを含有する。 (イ) 一般式[Formula] (wherein R ³ and R ⁴ are hydrogen atoms, alkyl groups optionally substituted with hydroxyl groups, or alkoxyalkyl represented by CnH ₂ nOR (n = 1 to 3, R represents an alkyl group) and R ³ and R ⁴ are not hydrogen atoms at the same time). The main points are as follows. The present invention will be explained in more detail below. The titration reagent for moisture measurement of the present invention can be suitably used as a titration reagent for both volumetric titration and coulometric titration, and can be used not only as a one-component reagent, but also as a one-component titration reagent.
It can also be used as a two-component reagent. The titration reagent for moisture measurement of the present invention must contain iodine or an iodide, sulfur dioxide, and a specific amine. When the titration reagent for moisture measurement of the present invention is used as a one-component reagent, it contains iodine or an iodide as the iodine component, and when it is used as a two-component reagent, it contains iodine. Therefore, iodine (single substance) is usually used, but in the case of water measurement by coulometric titration, even if it is added in the form of iodine (single substance) at the time of reagent preparation, all iodine is added immediately before injecting the sample to be measured. Since it is present as a oxide ion, iodine or an iodide may be used as appropriate by a titration method. Examples of the iodide include tetrabutylammonium iodide. The concentration of iodine or iodide is 0.01 to 0.4 mol/, preferably 0.03 to 0.4 mol/in terms of iodide ion.
It is in the range of 0.10 mol/. Generally, in a coulometric titration reagent, if the concentration of iodide ions is too high, the reaction rate tends to be slow, and if it is too low, the current efficiency tends to be low, so iodide is contained within this concentration range. Next, sulfur dioxide has the effect of accelerating the reaction and can be present in excess. However, it is usually in the range of 0.3 to 2 mol/particularly 0.6 to 2 mol/
It is preferable to contain it in a range of 1.5 mol/. Moreover, the titration reagent for moisture measurement of the present invention contains the specific amine described below. That is, it contains at least one amine selected from the group consisting of (a), (b), (c), and (d) below. (a) General formula

【式】（式中、R³及びR⁴ は水素原子、水酸基で置換されていてもよいア
ルキル基、又はCnH₂nOR（ｎ＝１〜３、Ｒは
アルキル基を表わす）で示されるアルコキシア
ルキル基であり、R³及びR⁴が同時に水素原子
であることはない）で表わされるアミン。前記(イ)に分類されるアミンにおいてR¹及びR²
は、水素原子、アルキル基、隣接するＮ原子と共
に閉環してもよいアルキレン基、ピリジル基又は
ピロリジニル基であるが、この中で、アルキル基
としては炭素数１〜４のアルキル基が好適であ
る。具体的には、２−メチルアミノピリジン、２−
ジメチルアミノピリジン、４−ジメチルアミノピ
リジン、４−ピロリジニルピリジン、２，2′−ジ
ピリジルアミンなどが挙げられる。以上の中でも特に、２−ジメチルアミノピリジ
ン、４−ジメチルアミノピリジンを使用すること
が好ましい。 (ロ)に分類されるアミンにおいてR³及びR⁴は前
記したとおりであらるが、その中で、水酸基で置
換されていてもよいアルキル基としては特に水酸
基で置換されていてもよい炭素数１〜４のアルキ
ル基が好ましく、また、CnH₂nOR（ｎ＝１〜３）
で示されるものとしてはＲが炭素数１〜４のアル
キル基、特にメチル基又はエチル基であるものが
好適に用いられる。具体的には、２−ピリジンエタノール、２−ピ
リジンプロパノール、２，６−ピリジンジメタノ
ール、２−メトキシエチルピリジンなどが挙げら
れる。以上の中でも特に２−ピリジンエタノールを使
用することが好ましい。上述したアミンの濃度は、二酸化硫黄に対する
モル比で0.3／１〜３／１、特に0.7／１〜２／１
の割合で含有させることが好ましい。上記した、ヨウ素又はヨウ素化物、二酸化硫黄
及びアミンの各成分は通常、カール・フイシヤー
試薬におい一般的に使用されている、メタノー
ル、エタノール、イソプロパノール、メチルセロ
ソルブ、クロロホルム、四塩化炭素などの溶媒又
はこれらの混合溶媒に前述した濃度範囲で溶解さ
せて水分測定用試薬とする。また、二液型試薬においては、前記した二酸化
硫黄及びアミンを含有する溶液Ａ（溶剤）と、ヨ
ウ素を含有する溶液Ｂ（滴定剤）とに分けておく
ものの、一液型試薬と本質的な差異はないので、
前記した二酸化硫黄及びアミンと、ヨウ素とを前
述した濃度範囲で夫々上記した溶媒中に溶解させ
ておけばよい。以下に実施例により本発明を更に具体的に説明
するが、本発明はその要旨を超えない限り以下の
実施例によつて限定されるものではない。実施例１〜４（電量滴定用の一液型試薬）ヨウ素0.64ｇを3M二酸化硫黄／メタノール溶
液34mlに溶解後水冷し、この溶液に、表−１に示
すアミンを表−１に示す添加量で夫々添加し、更
にクロロホルム25mlを加えた後メタノールで100
mlとし、滴定試薬を調製した。市販のカール・フ
イシヤー電量滴定装置（デイジタル微量水分測定
装置CA−02、三菱化成工業(株)社製）の陽極室に
得られた溶液の全量を入れ、陰極室には二酸化硫
黄1M及び４−ジメチルアミノピリジン1.1Mを含
有したメタノール溶液と四塩化炭素の４：１の混
合溶液を入れた。被水分測定試料として表−１に
示す添加量の水を添加して上記電量滴定装置の操
作法に従つて水分測定を行なつた。結果を表−１
に示す。実施例５〜７（容量滴定用の二液型試薬） 3M二酸化硫黄／メタノール溶液34mlを水冷し
ながら表−１に示すアミンを表−１に示す添加量
で夫々添加し、メタノールで100mlとした（溶液
Ａ）。ヨウ素23ｇをメタノール500mlに溶解したも
のを溶液Ｂとした。市販の容量滴定装置（カー
ル・フイシヤー自動滴定装置KF−01三菱化成工
業(株)社製）の滴定容器に上記溶液Ａを50ml入れ被
水分測定試料として水を表−１に示す添加量で添
加して溶液Ｂで上記装置の操作法に従つて水分測
定を行なつた。結果を表−１に示す。[Formula] (wherein R ³ and R ⁴ are hydrogen atoms, alkyl groups optionally substituted with hydroxyl groups, or alkoxyalkyl represented by CnH ₂ nOR (n = 1 to 3, R represents an alkyl group) and R ³ and R ⁴ are not hydrogen atoms at the same time). R ¹ and R ² in the amines classified as (a) above
is a hydrogen atom, an alkyl group, an alkylene group which may be ring-closed together with an adjacent N atom, a pyridyl group or a pyrrolidinyl group, and among these, an alkyl group having 1 to 4 carbon atoms is preferable as the alkyl group. . Specifically, 2-methylaminopyridine, 2-
Examples include dimethylaminopyridine, 4-dimethylaminopyridine, 4-pyrrolidinylpyridine, and 2,2'-dipyridylamine. Among the above, it is particularly preferable to use 2-dimethylaminopyridine and 4-dimethylaminopyridine. In the amines classified as (b), R ³ and R ⁴ are as described above, but among them, the alkyl group that may be substituted with a hydroxyl group is particularly the number of carbon atoms that may be substituted with a hydroxyl group. 1 to 4 alkyl groups are preferred, and CnH ₂ nOR (n = 1 to 3)
Among the compounds represented by the above, those in which R is an alkyl group having 1 to 4 carbon atoms, particularly a methyl group or an ethyl group, are preferably used. Specific examples include 2-pyridine ethanol, 2-pyridine propanol, 2,6-pyridine dimethanol, and 2-methoxyethylpyridine. Among the above, it is particularly preferable to use 2-pyridineethanol. The concentration of the abovementioned amines in molar ratio to sulfur dioxide is between 0.3/1 and 3/1, in particular between 0.7/1 and 2/1.
It is preferable to contain it in a proportion of . The iodine or iodide, sulfur dioxide, and amine components mentioned above are typically used in solvents such as methanol, ethanol, isopropanol, methyl cellosolve, chloroform, carbon tetrachloride, etc., or solvents commonly used in Karl-Fuchscher reagents. A reagent for moisture measurement is prepared by dissolving the above-mentioned concentration range in a mixed solvent. In addition, although the two-component reagent is separated into the above-mentioned solution A (solvent) containing sulfur dioxide and amine and solution B (titrant) containing iodine, the essential difference between the one-component reagent and Since there is no difference,
The above-mentioned sulfur dioxide and amine, and iodine may be dissolved in the above-mentioned solvent in the above-mentioned concentration ranges, respectively. EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. Examples 1 to 4 (one-component reagent for coulometric titration) Dissolve 0.64 g of iodine in 34 ml of 3M sulfur dioxide/methanol solution, cool with water, and add the amine shown in Table 1 to this solution in the amount shown in Table 1. After adding 25 ml of chloroform, dilute to 100 ml with methanol.
ml and prepared a titration reagent. The entire amount of the obtained solution was put into the anode chamber of a commercially available Karl-Fuchscher coulometric titration device (digital trace moisture measuring device CA-02, manufactured by Mitsubishi Chemical Industries, Ltd.), and the cathode chamber was filled with 1M sulfur dioxide and 4- A 4:1 mixed solution of a methanol solution containing 1.1 M of dimethylaminopyridine and carbon tetrachloride was added. Water in the amount shown in Table 1 was added as a sample to be measured for water content, and the water content was measured according to the operating method of the coulometric titration device described above. Table 1 shows the results.
Shown below. Examples 5 to 7 (Two-component reagent for volumetric titration) While cooling 34 ml of a 3M sulfur dioxide/methanol solution with water, the amines shown in Table 1 were added in the amounts shown in Table 1, and the volume was made up to 100 ml with methanol. (Solution A). Solution B was prepared by dissolving 23 g of iodine in 500 ml of methanol. Put 50 ml of the above solution A into the titration container of a commercially available volumetric titrator (Karl Fischer automatic titrator KF-01 manufactured by Mitsubishi Chemical Industries, Ltd.) and add water in the amount shown in Table 1 as a sample for measuring moisture content. Then, moisture content was measured using solution B according to the operating method of the apparatus described above. The results are shown in Table-1.

【表】実施例５被水分測定試料として水の代わりに一定量のカ
ーボネート系化合物を添加して、その水分量を測
定した以外、実施例１と同様にして水分測定を行
なつた。水分測定を５回繰返し、その平均値を結
果として表−２に示す。比較例１ピリジンを含む市販のカール・フイシヤー試薬
アクアミクロンＡ（三菱化成工業(株)社製）を滴定
試薬とした以外は実施例８と同様の操作で同一の
カーボネート系化合物の同量に含まれる水分量を
測定した。水分測定を５回繰返し、その平均値を
結果として表−２に示す。比較例２イミダゾールを含む市販のカール・フイシヤー
試薬クーロマートＡ（リーデル・デ・ヘーン社製）
を滴定試薬とした以外は、比較例１と同様にして
水分測定を行なつた。結果を表−２に示す。[Table] Example 5 Moisture measurement was carried out in the same manner as in Example 1, except that instead of water, a certain amount of a carbonate compound was added as a moisture measurement sample and the moisture content was measured. The moisture measurement was repeated five times, and the average value is shown in Table 2. Comparative Example 1 The same procedure as in Example 8 was carried out except that the commercially available Karl-Fuchscher reagent Aquamicron A (manufactured by Mitsubishi Chemical Industries, Ltd.) containing pyridine was used as the titration reagent. The amount of moisture absorbed was measured. The moisture measurement was repeated five times, and the average value is shown in Table 2. Comparative Example 2 Commercially available Karl-Fuchscher reagent Coulomat A (manufactured by Riedel de Haene) containing imidazole
Moisture measurement was carried out in the same manner as in Comparative Example 1, except that the titration reagent was used. The results are shown in Table-2.

【表】実施例６（容量滴定用の一液型試薬）ヨウ素71.1ｇを3M二酸化硫黄／メチルセロソ
ルブ溶液333mlに溶解後、水冷しながら、この溶
液に２−メチルアミノピリジン162ｇを添加し、
メチルセロソルブで１とした。この溶液を滴定
剤とし、市販のメタノールを滴定溶剤として市販
の容量滴定装置（カール・フイシヤー自動滴定装
置KF−01三菱化成工業(株)社製）で10.0mgの水を
添加して該装置の操作法に従つて水分測定を行な
つた。５回の測定での測定量の平均値は水分測定
値10.1mg、精度±1.0％、測定所要時間３分30秒
であつた。[Table] Example 6 (One-component reagent for volumetric titration) After dissolving 71.1 g of iodine in 333 ml of 3M sulfur dioxide/methyl cellosolve solution, 162 g of 2-methylaminopyridine was added to this solution while cooling with water.
It was set to 1 with methyl cellosolve. This solution was used as a titrant, commercially available methanol was used as a titration solvent, and 10.0 mg of water was added to the apparatus using a commercially available volumetric titrator (Karl Fuchscher automatic titrator KF-01 manufactured by Mitsubishi Chemical Industries, Ltd.). Moisture measurement was performed according to the operating instructions. The average value of the measured amount in the five measurements was 10.1 mg of moisture, the accuracy was ±1.0%, and the measurement time was 3 minutes and 30 seconds.

Claims

[Claims] 1. Iodine or an iodide, sulfur dioxide, and at least one selected from the group consisting of (a) and (b) below.
Titration reagent for moisture measurement containing a specific amine ( _a ⁾ General formula , pyridyl group or pyrrolidinyl group). (b) General formula [Formula] (wherein R ³ and R ⁴ are a hydrogen atom, an alkyl group which may be substituted with a hydroxyl group, or CnH ₂ nOR (n = 1 to 3, R represents an alkyl group) An amine represented by an alkoxyalkyl group represented by R ³ and R ⁴ are not hydrogen atoms at the same time. 2. In a titration reagent consisting of a solution A containing sulfur dioxide and an amine and a solution B containing iodine, the amine in the solution A contains at least one amine selected from the group consisting of (a) and (b) below. A titration reagent for measuring moisture content. (a) An amine represented by the general formula [Formula] (wherein R ¹ and R ₂ are a hydrogen atom, an alkyl group, an alkylene group which may be ring-closed together with the adjacent N atom, a pyridyl group, or a pyrrolidinyl group) . (b) General formula [Formula] (wherein R ³ and R ⁴ are a hydrogen atom, an alkyl group which may be substituted with a hydroxyl group, or CnH ₂ nOR (n = 1 to 3, R represents an alkyl group) An amine represented by an alkoxyalkyl group represented by R ³ and R ⁴ are not hydrogen atoms at the same time. 3 The molar ratio of amine to sulfur dioxide is 0.3/
The titration reagent for moisture measurement according to claim 1, characterized in that the titration reagent is in the range of 1 to 3/1. 4 Molar ratio of amine to sulfur dioxide 0.3/1
The titration reagent for moisture measurement according to claim 2, characterized in that the titration reagent is in the range of 3/1 to 3/1.