Ionic butylpyridinium, 1-, salt

Early in their work on molten salt electrolytes for thermal batteries, the Air Force Academy researchers surveyed the aluminium electroplating literature for electrolyte baths that might be suitable for a battery with an aluminium metal anode and chlorine cathode. They found a 1948 patent describing ionically conductive mixtures of AICI3 and 1-ethylpyridinium halides, mainly bromides [6]. Subsequently, the salt 1-butylpyridinium chloride/AlCl3 (another complicated pseudo-binary)... 

Beckmann rearrangements of several ketoximes were performed in room-temperature ionic liquids based on l,3-dialkylimida2olium or alkylpyridinium salts containing phosphorus compounds (such as PCI5) by Deng and Peng [59] (Scheme 5.1-31, BP = 1-butylpyridinium). Turnover numbers of up to 6.6 were observed, but the authors did not mention whether the ionic liquid could be reused. 

In none of the above cases has a reaction been performed whilst taking the EXAFS data. Hamill et al. [50] have investigated catalysis of the Heck reaction by palladium salts and complexes in room-temperature ionic liquids. On dissolution of palladium ethanoate in [BMIMj and N-butylpyridinium ([BP] ) hexafluorophos-phate and tetrafluoroborate ionic Hquids, and triethyl-hexyl ammonium bis(trifluo-romethanesulfonyl)imide, a gradual change from ethanoate coordination to the formation of palladium metal was observed in the Pd K-edge EXAFS, as shown in Figure 4.1-13. 

A 1 2 mixture of l-methyl-3-ethylimidazolium chloride and aluminum trichloride, an ionic liquid that melts below room temperature, has been recommended recently as solvent and catalyst for Friedel-Crafts alkylation and acylation reactions of aromatics (Boon et al., 1986), and as solvent for UV/Vis- and IR-spectroscopic investigations of transition metal halide complexes (Appleby et al., 1986). The corresponding 1-methyl-3-ethylimidazolium tetrachloroborate (as well as -butylpyridinium tetrachlo-roborate) represent new molten salt solvent systems, stable and liquid at room temperature (Williams et al., 1986). 

Ionic hquids are low melting organic salts that are liquids at ambient temperature. They typically contain quaternary ammonium cations such as l-butyl-3-methylimida-zolium- or N-butylpyridinium- with inorganic anions, such as tetrachloroaluminate or tetrafluoroborate (Chauvin and Helene, 1995 Freemantle, 1998). Melting points for these materials can be near -100°C, and the liquids are often thermally stable at temperatures approaching 200°C. 

Other cation combinations with [BF4] and [PFelectrochemical systems. Although N-butylpyridinium tetrafluorobo-rate [bpyr][BF4] is known to be a RTIL [53], the lower electrochemical stability of pyridinium-based cations relative to imidazolium limits their electrochemical applicability. On the other hand, pyrrolidinium-based cations are known to be more electrochemically stable than imidazolium salts, N-alkyl-N-methylpyrrolidinium salts of [BF4] and [PFf,] are made less attractive to researchers by the fact that they are solids at room temperature [54, 55]. Therefore, most of the electrochemical investigations of ionic liquids containing [BF4] and [PF6] have focused on [BMIM][PF6], [BMIM][BF4] and, to a lesser extent, [EMIM][BF4]. 

Ionic liquids (ILs), previously known as molten salts, were mainly used in electrochemistry studies due to their ionic nature. The most important step in the chemistry of the ILs occurred when Osteryoung described a mixture of 1-(1-butylpyridinium)-chloride and aluminium chloride which was liquid at room temperature30. Later on, Wilkes discovered other ionic liquids based on dialkylimidazolium salts that featured even more convenient physical and electrochemical properties than the butylpyridinium salts3i. 

The room-temperature chloroaluminate(lll) ionic liquids are the most important members of the first generation of ionic liquids, developed in the second half of the last century The room-temperature halogenoaluminate(III) ionic liquids are extremely sensitive to moisture and must be handled imder an inert atmosphere. Preparation of the halogcno-aluminate(III) ionic liquids is simple a quaternary ammonium (QUAT) halide, e.g. an imidazolium or pyridinium halide, is directly mixed with AICI3 in the ratio necessary to generate the composition required. Upon mixing, an exothermic reaction occurs and the two solids melt into a liquid. The first report on the formation of a room temperature liquid salt, based on the combination of 1-butylpyridinium with AICI3 in the relative molar proportions 1 2 (X =... 

Zhu and coworkers [22] reported an asymmetric hydrogenation of aromatic ketones in the presence of a rhodacarborane-based chiral catalyst 17, which was derived from rhodacarborane precursor 16 and (R)-BINAP, in ionic liquids (Scheme 7.5). The hydrogenations of acetophenone in the presence ofthe catalyst precursor 16 and (R)-BINAP (0.001 0.0015 for acetophenone) were performed in the ionic liquid medium such as [omim][BF4], [brnim lh7,, or a new hquid salt comprised of 1-carbododecaborate ions and N-n-butylpyridinium (BP) ions, [BP][CB1XioHi2], and tetrahydrofuran (THF) at 50°C under H2 (12atm) for 12h. As shown in Table 7.5, the catalytic activities and enantioselectivities in ionic liquids (entries 1-3) were higher in comparison with those obtained in TH F (entry... 

This is of course not the case when working with room temperature ionic liquid systems. Electrochemical and spectroscopic studies of cobalt, copper, and nickel, have been carried out in the AlClj-butylpyridinium chloride molten salt system. The direct current and pulsed current electrodeposition of Ni-Al alloys has also been shown in acidic AlCls-butylpyridinium chloride ionic liquids. This particular alloy has also been shown to be successful in AlCl3-[C2-mim]Cl ashave Co-Al andCu-Al. Electrochemical techniques can also be used to calculate the diffusion coefficients of metal ions. Table 21.2.6 shows the calculated diffusion coefficients and stokes-Einstein products of cobalt(II), copper(I), nickel(II) and zinc(II) in the 40-60 mol% [Cj-mimlCl-AlClj ionic liquid. 

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