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| 1.
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論文
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平山, 直樹
概要:
金沢大学自然科学研究科<br />Bronsted酸であるキレート試薬(いわゆるキレート抽出剤)を用いてイオン液体相へ金属イオンの抽出を行う「イオン液体キレート抽出系」について,従来の有機溶媒を抽出相とするキレート抽出系との相違点を中心に検
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討を行った.この系は,カチオン交換によるイオン液体抽出系とは異なり,原理的に金属イオンの逆抽出回収が容易に可能である.2-テノイルトリフルオロアセトンを用いた2価金属イオンの抽出では,金属イオンによって抽出種が異なり,中性配位不飽和(水和)錯体又はアニオン性錯体として抽出された.また,中性種とアニオン性種とでは,抽出相イオン液体を変化させたときの抽出定数の変化に差異が見られた.一方,8-ヒドロキシキノリンを用いた場合には,検討した2価金属イオンはすべて中性錯体として抽出された.更に,8-(トリフルオロメタンスルホンアミド)キノリンを抽出剤として用いた検討の結果から,抽出剤中のトリフルオロメチル基の存在がアニオン性抽出種のイオン液体相内における安定化に一定の寄与を果たしていることが示唆された. An "ionic liquid chelate extraction system", which is a novel liquid-liquid extraction method for the extractive separation of metal cations into the ionic liquid extraction phase with a chelate extractant, was investigated mainly from the point of difference from a normal chelate extraction system using a volatile organic solvent as the extraction phase. In this system, the extracted metals are easily recoverd by using back-extraction into an acidic solution. In the extraction of divalent metal cations (M^<2+>) with 2-thenoyltrifluoroacetone (Htta) (or other β-diketone having trifluoromethyl group), some metals were extracted into the 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF_6]) extraction phase as coordination-unsaturated (hydrated) neutral complexes (M(tta)_2(H_2O)_n), whereas others were extracted as coordination-saturated anionic complexes (M(tta)_3^-) with anion-exchange reactions. The extractability of the former species was reduced by using a more hydrophilic ionic liquid as the extraction phase, whereas that of the latter was enhanced. On the contrary, the use of 8-hydroxyquinoline (Hq) (or its derivative) as the extractant resulted in the extraction of M^<2+> into [bmim] [PF_6] as neutral M(q)_2(H_2O)_n. Furthermore, a comparison of the extraction behavior of M^<2+> with 8-(trifluoromethanesulfonamido) quinoline (H(CF_3)sq) having a trifluoromethyl group with that with 8-(methanesulfonamido) quinoline (H(CH_3)sq) suggested that the existence of a trifluoromethyl group in an chelate extractant contributes to an enhancement of the extractability for an anionic complex into the ionic liquid extraction phase. In addition, a fundamental study was performed on an ionic liquid synergistic cation-exchange extraction system with co-using Htta and 18-crown-6 (18C6) as extractants for the selective extraction of trivalent light lanthanoids, such as lanthanum (La). In this system, La^<3+> was extracted into 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide as cationic ternary complexes, such as La(tta)_2(18C6)^+ and La (tta) (18C6)^<2+>.
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| 2.
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論文
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平山, 直樹
概要:
金沢大学理工研究域<br />Relationships between ion-chromatographic retention behaviors of several anions and their dissociation co
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nstants were studied from two standpoints. In Part 1,the influence of the dissociation equilibria on the measured capacity factor of a sample was interpreted. In this study, the ratio of the capacity factor of the sample to that of a standard anion was used for the analysis of the retention behavior. The dissociation constants and the ratio of the capacity factors of various species of the sample to that of the standard were calculated and the retention behavior was estimated. In Part 2,the differences in the retention times of substituted benzoate anions having similar structure were analyzed by dividing the substituent effect into an LFER-applicable effect term, a steric effect term and a positional effect correction term. The first was introduced by putting the theory of linear free energy relationships into the relationship between the anion-exchange equilibria and the dissociation equilibria. The second depends on kind and number of the introduced substituents, and the last on the position of them. Furthermore, the estimation of the retention times of these anions and the determination of the dissociation constants of substituted naphthoic acids were done.
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| 3.
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論文
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中川, 晴淳 ; 平山, 直樹 ; 本浄, 高治
概要:
The effect of a counterion was investigated in the solvent extraction of alkali metal ions using crown ether. Nitrobenzene was used as the solvent, 18-crown-6 was used as the extracting reagent, rubidium ion, which suits the cavity size of
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18-crown-6, was selected as the model of alkali metal ions. In order to vary the distribution of the electric charge and the hydrophobicity of the counterion, various substituted phenols were used as the counterion. The aximum extraction ratio of rubidium ion was increased with non-localization of the distribution of the electric charge and with its hydrophobicity higher. The maximum extraction ratio was increased by introducing chloro substituent to the counterion, but it was not more effective than introducing nitro substituent. The pH where the extraction curve rose depended upon the pK_a of the counterion. In this extraction system, the value of the pH controlled only the condition of the dissociation of the counterion.
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| 4.
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論文
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平山, 直樹
概要:
金沢大学理工研究域<br />2-ピリジルメチル基や1-ピラゾリルメチル基, 2-ヒドロキシフェニルメチル基などの"芳香環ペンダントアーム(pendantarm)"を複数有する多座配位子の, 陽イオン分離や陰イオン分離への分析化学的利用可能
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性について, 各種の基礎的な検討を行った. これらの配位子は疎水性や電子的効果, 構造的剛直性, 立体的選択性などに関し, 芳香環ペンダントアームに基因する特異性を有するため, 各種金属イオンの抽出分離において, 従来の抽出試薬とは異なる選択性を示した. 例えば, N,N-ビス(2-ヒドロキシフェニルメチル)-N,N'-ビス(2-ピリジルメチル)エチレンジアミン(H_2bbpen)による二価遷移金属イオンのキレート抽出選択性はIrving-Williams則に従わず, 配位子の空孔サイズに基づくイオンサイズ認識が行われていることが示唆された. 又, N,N'-ビス(5-ニトロサリチリデン)エチレンジアミン(H_2Nsalen)による三価ランタノイドイオンの抽出では, 配位子の構造的剛直性に基づく高い相互分離能が実現された. 更に, 各種金属イオンと強く錯形成したビス(2-ピリジルメチル)アミノ基(bpa-基)をイオンクロマトグラフィーの固定相陰イオン交換基として用いると, イオン交換と配位子交換の2種類の相互作用の併存により, 陰イオンのクロマトグラフ分離において, 溶出順序の反転など従来とは異なる分離機能が実現された. The analytical use of polydentate ligands having plural "aromatic-ring pendant arms," such as 2-pyridylmethyl, 1-pyrazolylmethyl and 2-hydroxyphenylmethyl groups, for not only the separation of cations, but also that of anions, was investigated fundamentally. These ligands generally have a specific nature at many points, such as hydrophobicity, electric effects, structural rigidity and sterical selectivity, originating from the aromatic-ring pendant arms; also, upon the mutual separation of many kinds of metal cations by solvent extraction they can act as extraction reagents having specific reaction selectivity. As one example, the extraction selectivity of divalent transition metal cations using N,N'-bis(2-hydroxyphenylmethyl)-N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine (H_2bbpen) did not agree with the Irving-Williams series of stability; it was suggested that ion-size recognition based on the cavity size of the ligand acted in this extraction system. Upon the extraction of trivalent lanthanoids, as another example, N,N'-bis(5-nitrosalicylidene)-1,2-ethanediamine (H_2Nsalen) showed high performance for their mutual separation, originating from the structural ligidity of the ligand. Furthermore, an immobilized charged complex between bis(2-pyridylmethyl)amino group (bpa-group) and a metal cation was useful as an anion-exchange group in ion chromatography, having specific anion selectivity originating from its additional ligand-exchange ability.
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| 5.
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論文
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平山, 直樹 ; Hirayama, Naoki
概要:
金沢大学理工研究域<br />金属イオンに対する多座配位子の配位における配位環境の三次元的制御を利用することにより、各種金属イオンおよび陰イオン種の高機能分離分析法を設計することを目的として、以下のような基礎的研究を行った。[1]三脚型3価
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四座配位子であるトリス(2-ヒドロキシ-3,5-ジメチルベンジル)アミンを用いる13族3価金属イオンのキレート抽出に関する検討を行い、三脚構造による配位環境の束縛とメチル置換基基因の立体障害とを巧妙に利用することによってガリウムイオンのみを選択的に抽出分離できることを見いだした。さらに、配位子結晶のX線構造解析の結果より、中性状態におけるこの配位子の水素結合状態が錯形成反応速度論的に比較的有利な状況をもたらしているということを見いだした。[2]無電荷配位子であるN,N-ビス(2-ピリジルメチル)アミノ基と2価遷移金属イオンとで構成される配位不飽和荷電金属錯体を陰イオン交換基として用いる新たなイオンクロマトグラフ法の開発に関する基礎検討を行い、イオン交換反応と配位子交換反応を巧妙に併用することにより、中心金属イオンのアクセプターとしての特性を利用した、配位性陰イオンの高機能クロマトグラフ分離を実現した。[3]各種のピリジン-2-カルボニル化合物とジアミン類とから合成される無電荷Schiff塩基を錯形成試薬に用いて、水-ニトロベンゼン系における2価遷移金属イオンのイオン対抽出選択性に及ぼすイミン窒素ドナー原子近傍の立体構造の効果について比較検討を行った。その結果、ドナー隣接炭素原子上の置換基や2つのイミン窒素原子間の架橋構造形態が抽出選択性に大きな影響を与えることが確かめられた。<br />研究課題/領域番号:11740409, 研究期間 (年度):1999 – 2000<br />出典：「配位環境の三次元的制御による高機能イオン分離系の構築」研究成果報告書 課題番号11740409（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （ https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-11740409/ ）を加工して作成
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