Hydrolysis of the Room Temperature Ionic Liquid, N,N-Diethyl-N-methyl-N-(2-methoxyethyl)ammonium Tetrafluoroborate

Abstract

Room temperature ionic liquids (RTILs) have engaged much attention in recent years, especially due to their use as environmentally friendly alternatives to typical organic solvents. Their negligible vapor pressures incentivize their use as green solvent alternatives relative to the typical volatile organic solvents. However, it is necessary to consider the entire life cycle of the RTIL; for example, the potential hazardous properties associated with its hydrolysis by-products (tetrafluoroborate hydrolysis) merit consideration. Using 19 F and 11 B NMR analyses, we present the observation of hydrolysis behavior of the aliphatic quaternary ammonium-based ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate (denoted as [DEME][BF 4]). It has been observed that the hydrolysis of [DEME][BF4] rapidly proceeds when the water concentration exceeds x > 80 (mol % H2O). 室温イオン液体 （RTILs）は蒸気圧が無視できる程低いことから，近年，典型的な揮発性有機溶媒の代替品となるグリーン溶媒 としての利用が期待されている。しかし，四フッ化ホウ酸等のフッ素を含むイオン液体では加水分解により有害な HF ができる可能 性も示唆されており， ライフサイ クル全体を考慮する必要がある。そこで我々は 19 F および 11 B NMR を用いて，脂肪族四級アンモニウ ム系イオン液体， N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate ([DEME][BF4]) の加水分解挙動の 濃度および時間依存を調べた。その結果，水濃度が x > 80 (mol % H2O) を超えると加水分解が急速に進行することが分かった。