Synthesis of the perdeuterated cellulose solvents 1-ethyl-3-methylimidazolium acetate (EMIM-OAc-d<sub>14</sub>) and 1-butyl-3-methylimidazolium acetate (BMIM-OAc-d<sub>18</sub>) and of 2-<sup>13</sup>C-butyl-3-methylimidazolium acetate
作者:Yuko Yoneda、Gerald Ebner、Toshiyuki Takano、Fumiaki Nakatsubo、Antje Potthast、Thomas Rosenau
DOI:10.1002/jlcr.1591
日期:2009.5.30
The syntheses of two perdeuterated ionic liquids (ILs), which have found use as solvents for cellulose derivatization and processing in addition, are described: 1-ethyl-3-methylimidazolium acetate (EMIM-OAc-d14) and 1-butyl–3-methylimidazolium acetate (BMIM-OAc-d18). The targets were obtained from imidazole in three-step sequences starting with butylation and ethylation, respectively. The resulting 1-alkyl imidazoles were purified, and subsequently methylated according to a novel protocol using dimethylcarbonate-d6. To obtain the 1-alkyl-3-methylimidazolium moiety, methylation of 1-alkylimidazoles proved to be superior to the conventional approach of alkylating 1-methylimidazole. Addition of acetic acid-d4 caused traceless degradation of the methylcarbonate counter anions, which were neatly exchanged for acetate. The IL 2-13C-butyl-3-methylimidazolium acetate, in which the isotopically enriched C-2 is a good NMR-indicator of side reactions and solvent–solute interactions, was synthesized according to the same reaction sequence, starting from 2-13C-1-alkylimidazole which, in turn, was obtained by reaction of glyoxale, alkylamine, ammonia and paraformaldehyde-13C. Copyright © 2009 John Wiley & Sons, Ltd.
描述了两种全氘化离子液体(ILs)的合成,这些离子液体不仅被用作纤维素衍生化和加工的溶剂,分别是1-乙基-3-甲基咪唑鎓乙酸盐(EMIM-OAc-d14)和1-丁基-3-甲基咪唑鎓乙酸盐(BMIM-OAc-d18)。这些目标化合物分别从咪唑出发,通过三步反应合成,首先进行丁基化和乙基化。得到的1-烷基咪唑被纯化后,随后根据一种新颖的协议使用六氟化二甲基碳酸酯进行甲基化。为了获得1-烷基-3-甲基咪唑鎓基团,1-烷基咪唑的甲基化证明比传统的1-甲基咪唑烷基化方法更优。在反应中添加二氘乙酸使甲基碳酸酯阴离子无痕降解,干净地被乙酸根替代。IL 2-13C-丁基-3-甲基咪唑鎓乙酸盐,其中富含同位素的C-2是侧反应和溶剂-溶质相互作用的良好NMR指示剂,按照相同的反应序列合成,从2-13C-1-烷基咪唑开始,该化合物又是通过醛基、烷基胺、氨和甲醛-13C反应得到的。版权 © 2009 John Wiley & Sons, Ltd.