Gas Chromatography–Mass Spectrometry of Trimethylsilyl Derivatives of Some Iminodicarboxylic Acids
作者:Katsuhiro Kawashiro、Shiro Morimoto、Hideyuki Yoshida
DOI:10.1246/bcsj.57.2871
日期:1984.10
Trimethylsilylation of eight iminodicarboxylic acids (IDCAs) with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) or N,O-bis(trimethylsilyl)acetamide was studied under various reaction conditions. The IDCAs include iminodiacetic acid (1), 2- and 3-(carboxymethylamino)propionic acids (2 and 3), 2,2′-, 2,3′-, and 3,3′-iminodipropionic acids (4–6), N-methyliminodiacetic acid (7), and nitrilotriacetic acid (8). For 1–6, both bis- and tris(trimethylsilyl) (TMS) derivatives were formed under usual silylating conditions, although the proportion of amounts of the two derivatives varied depending on reaction conditions. This double derivatization was due to the steric hindrance of N-substituent group. However, under mild silylating conditions (BSTFA alone, 120 °C, 30 min), 1–6 yielded only the di-TMS derivatives. Upon electron impact at 20 eV, both the di- and tri-TMS derivatives showed simple spectra with a molecular (M+) ion and M −15 (loss of CH3). The α,α′-IDCAs (1, 2, 4, 7, and 8) are characterized by fragments M −43 (loss of CH3 and CO) and M −117 (loss of COOTMS) (base peak). On the other hand, the β,β′-IDCA (6) is characterized by fragments M −57 (loss of CH3, CH2, and CO) and prominent M −131 (loss of CH2COOTMS). The α,β′-IDCAs (3 and 5) exhibit both the fragments characteristic of α,α′- and β,β′-IDCAs, M −43, M −57, M −117, and M −131. However, base beaks are usually the fragment M −117 and not M −131.
在不同的反应条件下,研究了八种亚氨基二羧酸(IDCA)与 N,O-双(三甲基硅基)三氟乙酰胺(BSTFA)或 N,O-双(三甲基硅基)乙酰胺的三甲基硅烷化反应。IDCA 包括亚氨基二醋酸(1)、2-和 3-(羧甲基氨基)丙酸(2 和 3)、2,2′-、2,3′- 和 3,3′- 亚氨基二丙酸(4-6)、N-甲基亚氨基二醋酸(7)和硝基三醋酸(8)。对于 1-6,在通常的硅烷化条件下会形成双(三甲基硅基)和三(三甲基硅基)(TMS)衍生物,但这两种衍生物的数量比例因反应条件而异。这种双重衍生化是由于 N 取代基团的立体阻碍作用。然而,在温和的硅烷化条件下(仅 BSTFA,120 °C,30 分钟),1-6 只产生二-TMS 衍生物。在 20 eV 的电子撞击下,二-TMS 和三-TMS 衍生物都显示出分子(M+)离子和 M -15(失去 CH3)的简单光谱。α,α′-IDCA(1、2、4、7 和 8)的特征为碎片 M -43(失去 CH3 和 CO)和 M -117(失去 COOTMS)(基峰)。另一方面,β,β′-IDCA(6)的特征是 M -57 片段(CH3、CH2 和 CO 的损失)和突出的 M -131 片段(CH2COOTMS 的损失)。α,β′-IDCA(3 和 5)同时表现出 α,α′- 和 β,β′-IDCA 的特征片段 M -43、M -57、M -117 和 M -131。然而,基喙通常是碎片 M -117 而不是 M -131。