<sup>1</sup>H and<sup>13</sup>C NMR Detection of the Carbocations or Zwitterions from Rhodamine B Base, a Fluoran-Based Black Color Former, Trityl Benzoate, and Methoxy-Substituted Trityl Chlorides in the Presence of Alkali Metal or Alkaline Earth Metal Perchlorates in Acetonitrile Solution
作者:Masashi Hojo、Tadaharu Ueda、Masanori Yamasaki、Akihiko Inoue、Sumio Tokita、Mitsuhiro Yanagita
DOI:10.1246/bcsj.75.1569
日期:2002.7
The cleavage of C–O bonds in two fluoran-based dyes by the addition of alkali metal (M+ = Li+, Na+) and alkaline earth metal (M2+ = Mg2+, Ba2+) perchlorates in acetonitrile solution was examined by means of UV-visible absorption and 1H and 13C NMR spectroscopy at room temperature. Although the 1H NMR signals of the xanthene part of Rhodamine B base (3′,6′-bis(diethylamino)fluoran) were shifted toward lower fields, those of the isobenzofuran (or the benzoate) part were not shifted much upon the addition of M+ and M2+. The appearance of 13C signals at 163.6 and 162.4 ppm (vs TMS) in the presence of Li+ and Ba2+, respectively, confirmed the formation of the zwitterions from Rhodamine B base. The assignments of the 1H and 13C signals were performed by the HMBC method. The colored zwitterion of a practical black color former, 2′-anilino-6′-dibutylamino-3′-methylspiro[3H-isobenzofuran-1, 9′-(9H)xanthene]-3-one, was produced by the addition of M+ and M2+. The 13C NMR signals at 162.2 and 159.8 ppm in the presence of 2.0 mol dm-3 Mg(ClO4)2 and Ba(ClO4)2, respectively, gave conclusive evidence of the formation of the sp2-hybrid carbon center for the black color former. The interaction between the metal ions and the zwitterions from the fluoran-based dyes decreased as Mg2+ > Ba2+ > Li+ > Na+. The 1 : 1 complex formation constants with the metal ions for both dyes were evaluated based on the UV-visible absorption data. The smaller formation constants of the black color former, compared with those of Rhodamine B base, indicate some more difficulty in the cleavage of the γ-lactone ring, which is probably based on the asymmetric structure of the compound, i.e, only a single dibutylamono-group at the 3′- and 6′-positions. The evidence for the formation of both the trityl cation and the benzoate ion was obtained by the 1H NMR signals from trityl benzoate in the presence of Mg(ClO4)2 in CD3CN containing a small amount of CF3SO3D. The C–Cl bond cleavage of 4-methoxy, 4,4′-dimethoxy, and 4,4′,4′′-trimethoxytrityl chlorides, through the chemical interaction between Ba2+ and Cl- in acetonitrile soluition, was justified by our 13C NMR results.
室温下,通过紫外-可见吸收以及 1H 和 13C NMR 光谱,研究了在乙腈溶液中加入碱金属(M+ = Li+、Na+)和碱土金属(M2+ = Mg2+、Ba2+)高氯酸盐对两种芴基染料中 C-O 键的裂解作用。虽然罗丹明 B 碱(3′,6′-双(二乙基氨基)荧烷)中的呫吨部分的 1H NMR 信号向低场移动,但在加入 M+ 和 M2+ 后,异苯并呋喃(或苯甲酸盐)部分的 1H NMR 信号移动不大。在 Li+ 和 Ba2+ 的存在下,分别在 163.6 和 162.4 ppm(相对于 TMS)出现的 13C 信号证实了罗丹明 B 碱形成了三元共轭物。1H 和 13C 信号的分配是通过 HMBC 方法进行的。通过添加 M+ 和 M2+,产生了实用黑色前体--2′-苯胺基-6′-二丁基氨基-3′-甲基螺[3H-异苯并呋喃-1,9′-(9H)氧杂蒽]-3-酮的有色齐聚物。在 2.0 mol dm-3 Mg(ClO4)2 和 Ba(ClO4)2 的存在下,13C NMR 信号分别为 162.2 和 159.8 ppm,这为黑色前体形成 sp2-杂化碳中心提供了确凿证据。金属离子与芴基染料中的齐聚物之间的相互作用按 Mg2+ > Ba2+ > Li+ > Na+ 的顺序递减。根据紫外可见吸收数据评估了两种染料与金属离子的 1 : 1 复合物形成常数。与罗丹明 B 碱的形成常数相比,黑色前者的形成常数较小,这表明γ-内酯环的裂解更为困难,这可能是基于化合物的不对称结构,即在 3′-和 6′-位置上只有一个二丁基氨基。在含有少量 CF3SO3D 的 CD3CN 中,苯甲酸三甲苯酯在 Mg(ClO4)2 的存在下产生的 1H NMR 信号证明了三甲苯酯阳离子和苯甲酸根离子的形成。13C NMR 结果证明,4-甲氧基、4,4′-二甲氧基和 4,4′,4′′-三甲氧基三苯甲基氯化物的 C-Cl 键是通过 Ba2+ 和 Cl- 在乙腈溶液中的化学作用裂解的。