Halide‐Free Synthesis of Hydrochalcogenide Ionic Liquids of the Type [Cation][HE] (E=S, Se, Te)

Abstract

We present the synthesis and thorough characterization of ionic liquids and organic salts based on hydrochalcogenide HE(-) (E=S, Se, Te) anions. Our approach is based on halide-, metal-, and water-free decarboxylation of methylcarbonate precursors under acidic conditions, resulting from the easily dissociating reagents H2 E. The compounds were characterized by elemental analysis, multinuclear NMR spectroscopy, thermal and single-crystal XRD analyses. The hydrosulfide salts were investigated with respect to their ability to dissolve elemental sulfur in varying stoichiometry. Thus-prepared polysulfide ILs were also analyzed by UV/Vis spectroscopy and cyclic voltammetry.

On Silylated Oxonium and Sulfonium Ions and Their Interaction with Weakly Coordinating Borate Anions

“…108° in T‐S‐T), which is also supported by the sum of all Si‐S‐Si angles with 329.0° and 326.6°, respectively. The Si−S bond lengths of both salts (ranging between 2.24–2.31 Å, average 2.256 and 2.251 Å) are in good agreement with those observed in T‐S‐T (2.152(2) Å) and T−S − (2.05–2.07, cf. Σ r cov (Si−S)=2.19 Å) .…”

N‐Heterocyclic Olefin–Carbon Dioxide and –Sulfur Dioxide Adducts: Structures and Interesting Reactivity Patterns

“…With respect to green IL synthesis protocols, this additional information is important as zwitterion 2 does not show an equally high activity in proton‐induced decarboxylation reactions as the methyl carbonate salt 1 . In our investigation of hydrochalcogenide ILs, we also noticed that higher concentrated methanol solutions of carboxylate 2 reacted significantly more slowly than dilute solutions containing only the methyl carbonate salt. A mixture of nonseparable products may be the undesirable consequence in these IL syntheses.…”

“…This is exemplified by our attempted synthesis of 1‐ethyl‐2,3‐dimethylimidazolium tert‐ butylthiolate ( 5 ) from the corresponding methyl carbonate precursor. In contrast to H 2 S, the weaker acid t BuSH was not deprotonated by 1‐ethyl‐2,3‐dimethylimidazolium methyl carbonate in MeOH to any amount detectable by 1 H NMR spectroscopy. Apparently, the solvated anion t BuS − (MeOH) is more basic than MeOCO 2 − (MeOH).…”

Pseudo Halide Chemistry in Ionic Liquids with Decomposable Anions

“…For synthesizing a set of different trialkylmethylammonium pseudohalides (1X and 2X, Scheme 2) we first prepared trialk-ARTICLE ylmethylammonium methylcarbonates [Et 3 MeN][CO 3 Me] (1) and [nBu 3 MeN][CO 3 Me] (2) by a slightly changed literature protocol as illustrated in Scheme 1. [15][16][17][18][19][20] Subsequently, the syntheses of quaternary ammonium pseudohalides was achieved in the reaction of [Et 3 MeN][CO 3 Me] (1) and [nBu 3 MeN][CO 3 Me] (2) with the corresponding trimethylsilyl pseudohalogen compound (Scheme 2), a synthetic approach previously reported by Sundermeyer and co-workers [25] (see Supporting Information for further details). By this method, all pseudohalides 1X and 2X (X -= CN -, N 3 -, OCN -, and SCN -) could be obtained in nearly quantitative yields (90-99 %) as colorless solids.…”