The Catalytëc Halides. I. A Study of the Catalyst Couple, Aluminum Chloride—Hydrogen Chloride, and the Question of the Existence of HAlCl₄¹

Protic Ionic Liquids Can Be Both Free Proton Conductors and Benign Superacids .

“…There are evidently many possibilities, including protonated fluoroethers, still to be explored. If nothing else, the AlBr4 -/Al2Br7ratio achieved during a HBr/AlBr3 protonation at 1atm pressure of HBr, should provide, via the distinct 27 Al NMR resonances, a useful laboratory route to ordering and finally quantifying the basicities of very weak proton acceptors (like PFP and toluene) for general purposes. It might be particularly useful for the creation of a library of benign superacidic PILs, of tunable low vapor pressures, for chemical synthesis applications.…”

“…Firstly, proton transfer ionic liquids of highly ionic character are like aprotic ionic liquids in having low vapor pressures8 . Secondly, because HAlCl4 is unstable27 , any acid vapors over [PFPH…”

“…Remembering the manner in which Brown and Pearsall 26 created, in 1951, a "brilliant green" protic ionic liquid at -80ºC, by using a transient HAlCl4 27 to protonate toluene, we adopted transient HAlCl4 as the protonating agent -see the short red arrow in Table 1. Following Brown and Pearsall, dry HCl was bubbled through a stirred suspension of anhydrous AlCl3 in PFP.…”

“…Firstly, proton transfer ionic liquids of highly ionic character are like aprotic ionic liquids in having low vapor pressures 8 . Secondly, because HAlCl4 is unstable 27 , any acid vapors over [PFPH + ][AlCl4 -] superacid should consist only of HCl with a pKa of -7, and in the case of the brominated analog, even the HBr pressure should be low. Therefore, to the extent that it remains liquid at ambient temperature, [PFPH + ][AlCl4 -], and especially its brominated analog, should serve as benign liquid superacids, e.g.…”

Protic Ionic Liquids Can Be Both Free Proton Conductors and Benign Superacids .

“…Firstly, proton transfer ionic liquids of highly ionic character are like aprotic ionic liquids in having low vapor pressures 8 . Secondly, because HAlCl4 is unstable 27 , any acid vapors over [PFPH + ][AlCl4 -] superacid should consist only of HCl with a pKa of -7, and Figure 1. DSC upscans at 10Ks -1 for different proton transfer salts obtained by protonation of different weak bases by reaction with HCl/AlCl3 and HBr/AlBr3 at ambient pressure.…”