Guanidinium-Based Ionic Liquids

Abstract

Cyclic (subset=N+<, subset = imidazolidine 3 and 4, hexahydro-pyrimidine 7 and 8, tetrahydro-1,3,5-oxadiazine 12, and triazoline 15 and 16) and acyclic [(R2N)2C=N+<, 19] guanidinium-based salts were synthesized via the quaternization of guanidine derivatives with nitric or perchloric acid or with iodomethane followed by metathesis reaction with silver nitrate, silver perchlorate, or ammonium dinitroamide. The structure of 15d was confirmed by single-crystal X-ray analysis. Most of the salts exhibited low melting points and good thermal stabilities. Their densities range between 1.2 and 1.5 g/cm3. Standard molar enthalpies of formation were calculated from experimentally determined constant-volume combustion energies obtained using an oxygen bomb calorimeter.

Crystal structure of 1,1,3,3-tetramethyl-2-(1,3-dimethylimidazolidin-2- yl)guanidinium chloride, (C10H24N5)Cl

“…Becauseo ft he unique role in molecular recognition, guanidiniumand its derivatives become one of the key subjects in life science research [4]. Additionally, guanidinium derivatives have attracted interests during recent years due to the wide use in chemical and biological systems [5]. The asymmetric unit of the title crystal structure contains one cation 1,1,3,3-tetramethyl-2-(1,3-dimethylimidazolidin-2-yl)-guanidinium and one chloride anion.…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 17, 2006) and the discipline

“…In the next paper by Pu, Chen, and Fang [208] report that their theoretical findings that the 5-H proton on the imidazole ring of 1-ethyl-3-methyl-imidazolium fluoride has catalytic activity for butene double bond isomerization similar to that of the 4-H proton [209]. As befits increasing interest in general in ionic liquids, recently measurements of their enthalpies of formation have been reported [210][211][212].…”

Ionic Liquids as Energetic Materials

“…22 Heats of formation were determined for seven of the new substituted imidazolium salts (23,24,30,31,32,34,35). Interestingly, while the 5-nitro perchlorate and nitrate salts (23,24) have quite high negative heats, the 2-azido salts (34,35) have modestly high positive AHfs but rather high Tm values. Not surprisingly, 34 (perchlorate) has a positive AHf that is -3.5 times larger than 35 (nitrate).…”

“…Syntheses and Thermal Properties of Guandinium-Based Salts. 23 While most of the 30 guanidinium-based ionic liquids synthesized show low melting points (< 100 'C), only 12 had melting points or phase transition temperatures < 25 'C (Scheme 6 -imidazolium and triazolium derivatives). Of the 12, six (63, 67, 70, 71, 71, 74) exhibit positive heats of formation ( ; f From X-ray structure.…”