Synthesis of sequentially deuterated 1‐n‐Butyl‐3‐methylimidazolium ionic liquids

Abstract

Deuterium isotopologues of the ionic liquid (IL) 1-n-butyl-3-methylimidazolium chloride ([C 4 mim]Cl) sequentially labeled on the C-1 00 , C-1 0 , C-2 0 , C-3 0 , and C-4 0 positions of the N-alkyl groups were prepared following a strategy that minimizes the number of distinct reactions through the use of analogous synthetic routes. In several cases, good yields after the initial deuterium incorporation reaction were achieved by combining well-established chemical transformations into efficient single-step processes.

Observation of aliphatic C–H⋯X hydrogen bonds in imidazolium ionic liquids

“…1). 8 However, the 35 Cl and 37 Cl linewidths in the neat IL at 90 1C exceed 400 Hz and 250 Hz, respectively, 9 and isotope effects smaller than those observed in our previous work were expected. We therefore opted to employ 19 F as a probe, and for that purpose we prepared the corresponding BF 4 À and PF 6 À salts by standard metathesis reactions (see the ESI †).…”

Determining the relative strengths of aromatic and aliphatic C―H⋅⋅⋅X hydrogen bonds in imidazolium ionic liquids through measurement of H/D isotope effects on 19F nuclear shielding

“…As detailed earlier, the preparation of the deuterated isotopologues of [C 4 mim]PF 6 and [C 4 mim]BF 4 shown in Fig. was conveniently carried out following methodologies developed earlier . Deuterium incorporation levels above 95% were achieved in all cases.…”

“…1 was conveniently carried out following methodologies developed earlier. [15,18] Deuterium incorporation levels above 95% were achieved in all cases. Figure 2 shows 19 F NMR spectra obtained using coaxial tube systems containing 1 in the inner cavity and 1a, 1c, or 1e in the outer cavities.…”

“…1‐ n ‐Butyl‐3‐methylimidazolium bromide ([C 4 mim]Br) was prepared following reported methods . Deuterated 1‐ n ‐butyl‐3‐methylimidazolium salts 1d , 1e , 2d , and 2e were obtained as previously described . Potassium hexafluorophosphate and sodium tetrafluoroborate were purchased from Sigma‐Aldrich, Inc. (St. Louis, MO, USA) and used as received.…”

“…[17] Deuterated 1-n-butyl-3methylimidazolium salts 1d, 1e, 2d, and 2e were obtained as previously described. [15,18] Potassium hexafluorophosphate and sodium tetrafluoroborate were purchased from Sigma-Aldrich, Inc. (St. Louis, MO, USA) and used as received. IR spectra were recorded on a Shimadzu IRAffinity-1 FT-IR spectrophotometer equipped with a PIKE MIRacle ™ single reflection ATR accessory.…”