Pentaalkylmethylguanidinium methylcarbonates – versatile precursors for the preparation of halide-free and metal-free guanidinium-based ILs

Oelkers, Benjamin

doi:10.1039/c0gc00698j

Cited by 27 publications

(19 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The corresponding methylcarbonate salts are readily prepared in methanol solution by methylation of organic cation precursors with dimethyl carbonate under solvothermal conditions . In some cases, a solvent‐free isolation or even a solvent‐free synthesis are possible . The hydrosulfide salts ( 1 to 5 ) were prepared by introducing hydrogen sulfide gas into solutions of the respective methylcarbonate‐based ionic liquids in methanol at ambient temperature.…”

Section: Resultsmentioning

confidence: 99%

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

Finger

2016

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 99%

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

Finger

2016

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

show abstract

“…This route towards methyl‐onium methyl carbonates tolerates a vast number of starting nucleophiles, the only requirements being the thermal stability of the reagent towards elevated temperatures of around 130 °C and the stability of the resulting IL cations towards the basic and nucleophilic, potentially weakly solvated methyl carbonate anion and unselective cation carboxylations. In this respect, pentamethylguanidine is one of the few nucleophiles not suitable: A hexamethylguanidinium cation is attacked, whereas the sterically more protected methyl‐pentaalkylguanidinium cations are inert towards nucleophilic attack of methyl carbonate at 130 °C . 1‐Alkylimidazoles as nucleophiles are at the borderline of usability, as the ring protons of the resulting N‐heterocyclic cations are sufficiently acidic to be engaged in follow‐up reactions.…”

Section: Introductionmentioning

confidence: 99%

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

Finger

Guschlbauer

Harms

2016

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

Depending on the amount of methanol present in solution, CO adducts of N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) have been found to be in fully reversible equilibrium with the corresponding methyl carbonate salts [EMIm][OCO Me] and [EMMIm][OCO Me]. The reactivity pattern of representative 1-ethyl-3-methyl-NHO-CO adduct 4 has been investigated and compared with the corresponding NHC-CO zwitterion: The protonation of 4 with HX led to the imidazolium salts [NHO-CO H][X], which underwent decarboxylation to [EMMIm][X] in the presence of nucleophilic catalysts. NHO-CO zwitterion 4 can act as an efficient carboxylating agent towards CH acids such as acetonitrile. The [EMMIm] cyanoacetate and [EMMIm] cyanomalonate salts formed exemplify the first C-C bond-forming carboxylation reactions with NHO-activated CO . The reaction of the free NHO with dimethyl carbonate selectively led to methoxycarbonylated NHO, which is a perfect precursor for the synthesis of functionalized ILs [NHO-CO Me][X]. The first NHO-SO adduct was synthesized and structurally characterized; it showed a similar reactivity pattern, which allowed the synthesis of imidazolium methyl sulfites upon reaction with methanol.

show abstract

“…2). A similar type of disorder at the CN 3 moiety has been observed in the crystal structures of salts containing the N,N,N 0 ,N 0 ,N 00 ,N 00 -hexamethylguanidinium ion [see, for example: cyanate salt (Tiritiris & Kantlehner, 2015a); chloride salt (Oelkers & Sundermeyer, 2011)]. In the title salt, the central C-N bond lengths of both cations are in a range from 1.3329 (17) to 1.364 (16) Å , indicating partial double-bond character for all.…”

Section: Structure Descriptionmentioning

confidence: 82%

N,N,N′,N′,N′′-Pentamethyl-N′′-[2-(trimethylazaniumyl)ethyl]guanidinium bis(tetraphenylborate) acetone monosolvate

Tiritiris

Kantlehner

2016

IUCr Data

View full text Add to dashboard Cite

The asymmetric unit of the title solvated salt, C 11 H 28 N 4 2+ Á2C 24 H 20 B À ÁC 3 H 6 O, comprises two cations, four tetraphenylborate anions and two acetone molecules. One cation shows an orientational disorder at the CN 3 moiety and two sets of N-atom positions were found related by a 60 rotation, with a refined occupancy ratio of 0.935 (1):0.065 (1). The respective nitrogen-bonded -CH 2 and -CH 3 groups are included in the disorder model. The C-N bond lengths in the central CN 3 units of both guanidinium ions range between 1.3329 (17) and 1.364 (16) Å , indicating a degree of double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal-planar geometry and one positive charge is delocalized in the CN 3 plane. The C-N bond lengths in the terminal trimethylammonium groups have values close to a typical single bond, and the second positive charge is localized there. In the crystal, the guanidinium ions are connected by C-HÁ Á ÁO hydrogen bonds with the acetone molecules. C-HÁ Á Á interactions are present between the guanidinium and acetone hydrogen atoms and the phenyl rings of the tetraphenylborate ions, leading to the formation of a two-dimensional supramolecular pattern along the bc plane. Structure description!-Aminoalkylguanidines such as N 00 -[2-(dimethylamino)ethyl]-N,N,N 0 ,N 0 -tetramethylguanidine (Tiritiris & Kantlehner, 2012b) are well known in the literature. Electrophiles can attack at both the imine nitrogen of the guanidine function as well as on the nitrogen atom of the (dimethylamino)propyl group. By alkylation with two equivalents of dimethyl sulfate, a permethylated waxy guanidinium bis(methyl sulfate) salt was

show abstract

Pentaalkylmethylguanidinium methylcarbonates – versatile precursors for the preparation of halide-free and metal-free guanidinium-based ILs

Cited by 27 publications

References 50 publications

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

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

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

N,N,N′,N′,N′′-Pentamethyl-N′′-[2-(trimethylazaniumyl)ethyl]guanidinium bis(tetraphenylborate) acetone monosolvate

Contact Info

Product

Resources

About