1-butylpyridinium tetrafluoroborate

A review of solvent properties of, and organic reactivity in, ionic liquids demonstrates the relatively small number of quantitative studies of electrophilic aromatic substitution in these media.3 Studies mentioned in the review indicate conventional polar mechanisms. 1-Methylpyrrole reacts with acyl chlorides in the ionic liquid 1-butylpyridinium tetrafluoroborate to form the corresponding 2-acylpyrrole in the presence of a catalytic amount of ytterbium(III) trifluoromethanesulfonate.4 The ionic liquid-catalyst system is recyclable. Chloroindate(III) ionic liquids5 are catalytic media for the acylation, using acid chlorides and anhydrides, of naphthalene, benzene, and various substituted benzenes at 80-120 °C. Again the ionic liquid is recyclable. 

To reveal ionic transport behavior through self-diffusion studies [22], we choose four different ionic liquids l-ethyl-3-methylimidazolium tetrafluoro-borate (EMIBF4), l-ethyl-3-methylimidazolium l ii(trifluoromethylsulfonyl)imide (EMITFSI), 1-butylpyridinium tetrafluoroborate (BPBF4), 1-butylpyridinium, and Z7w(trifluoromethylsulfonyl)imide (BPTFSI) (Scheme 5.1). The ionic liquids are comprised of two different cations and anions, and they allow us to visualize the dependence of ionic transport behavior on structural variety from the comparative self-diffusion behavior. 

Bandres I, Royo FM, Gascon I, Castro M, Lafiiente C (2010) Anion influence on thermophysical properties of ionic liquids 1-butylpyridinium tetrafluoroborate and 1-butylpyridinium triflate. J Phys Chem B 114 3601-3607... 

One of the important new directions in the study of addition reactions of organozinc compounds to aldehydes is the use of ionic liquids. Usually, application of these compounds in reactions with common organometallic reagents has a serious problem ionic solvents are usually reactive toward them, particularly Grignard and organolithium derivatives. It has been recently reported that carbonyl compounds react with allylzinc bromide formed in situ from allyl bromide and zinc in the ionic liquid 3-butyl-l-methylimidazolium tetrafluoroborate, [bmim][BF4].285 Another important finding is that the more reactive ZnEt2 alkylates aldehydes in a number of ionic liquids at room temperature.286 The best yields (up to 96%) were obtained in A-butylpyridinium tetrafluoroborate, [bpy][BF4] (Scheme 107). 

The molar volumes at higher temperatures and the influence of the increasing temperature can be shown for N-butylpyridinium tetrafluoroborate. 

Ding, S.F., Wei, W., and Zhao, G.G., Direct electrochemical response of cytochrome c on a room temperature ionic liquid, N-butylpyridinium tetrafluoroborate, modified electrode, Electrochem. Commun., 9, 2203-2207, 2007. 

Heintz, A., Kulikov, D.V., and Verevkin, S.P., Thermodynamic properties of mixtures containing ionic liquids. 1. activity coefficients at infinite dilution of alkanes, alkenes, and alkylbenzenes in 4-methyl-n-butylpyridinium tetrafluoroborate using gas-liquid chromatography, /. Chem. Eng. Data, 46,1526-1529,2001. 

A -Butylpyridinium tetrafluoroborate, containing dissolved phosphorus pentachloride, allows catalytic Beckmann rearrangement of cyclohexanone oxime giving e-caprolactam with good conversion and selectivity <2001TL403>. The same ionic liquid containing dissolved ytterbium(m) trifluoromethanesulfonate was used to perform Friedel-Crafts acylation of furan and thiophene <2005JIG398>. 

Deng and his coworkers found that CO2 was reduced at a cupper cathode at —2.4 V vs. Ag/AgCl [42]. They successfully prepared cyclic carbonates by the reduction of CO2 in the presence of epoxides in various ionic liquids like [EMIM][BF4], [BMIMJiPFg], and A-butylpyridinium tetrafluoroborate [BPy][BF4] using a Cu cathode and Mg or A1 anode as shown in Scheme 8.16. This electrolysis is nonfaradaic reaction in which a small amount of electricity engaged in the electroreduction of CO2 generates catalytic species responsible for the addition of CO2 to epoxides to form cyclic carbonates. 

Nacci, whose procedure involved the use of the ionic solvent n-butylpyridinium tetrafluoroborate, reported a stereoselective synthesis of 2,3-dihydrofurans <03JOC4406>. 

Heintz A, Klasen D, Lehmann J K. Excess molar volumes and viscosities of binary mixtures of methanol and the ionic liquid 4-methyl-N-butylpyridinium tetrafluoroborate at 25, 40, and 50 °C. J. Solution Chem. 2002. 31, 467-476. 

An ionic liquid of a different type (n-butylpyridinium tetrafluoroborate, [BPy]BF4) has been used as a recyclable solvent for the reaction of 4-benzoylbutyric acids 40 with [hydroxy(2,4-dinitrobenzenesulfonyloxy)iodo]benzene (HDNIB) leading to 5-benzoyldihydro-2(3//)-furanones 41 (Scheme 6.16) [58]. 

Few more methods for the synthesis of 3,5-di-substituted 1,2,4-thiadiazole derivatives at room temperature have been reported using a variety of catalysts such as iodobenzene diacetate (IBD) or polymer-supported iodobenzene diacetate (PIBD) in dichloromethane [1], phenyliodine(III) diacetate in 1-n-butylpyridinium tetrafluoroborate (BPyBF4 ionic liquid) [2], IBX/TEAB in acetonitrile [3], and methyl bromocyanoacetate in methanol [4]. 

Ionic liquids have also played a central role in the rate acceleration of the MBH reaction.For example, when -butylpyridinium tetrafluoroborate was used as the solvent in the MBH reaction between a series of arylcarboxaldehydes 37a-d and activated alkenes in the presence of urotropine 38 (HMTA), the reaction times were dramatically reduced from 16-24 h to 4-8 h with equal or better yields. Presumably, the ionic liquid medium stabilized the polar intermediates found in the reaction pathway. 

Organomagnesium reagents can also be obtained from organic iodides and magnesium metal using ionic liquids like -butylpyridinium tetrafluoroborate ([bpy][Bp4]) as solvent. Some unusual reactivity of Grignard reagents was observed in these solutions. ... 

Since this time, further pulse radiolysis results have been reported in the ionic Hquids methyltributy-lammonium fcis(trifluoromethylsulfonyl)imide ([mtba] [TfjN]), N-butylpyridinium tetrafluoroborate ([bupy] [BF4]), and N-butyl-4-methylpyridinium hexafluorophosphate ([bupicllPF ]). The former Uq-uid was chosen because radiolysis produces solvated electrons that do not react with the parent ions and can thus be scavenged by reactive solutes (Equation 5.4). 

Behar, D., Neta, R, and Schultheisz, C., Reaction kinetics in ionic Hquids as studied by pulse radiolysis redox reactions in the solvents methyltributylammonium bis(trifluoromethylsulfonyl)-imide and N-butylpyridinium tetrafluoroborate, /. Phys. Chem. A, 106, 3139,2002. 

Garcia, J. Garcia, S. Torrecilla, J. S. Oliet, M. Rodriguez, F. (2010). Separation of toluene and heptane by liquid-liquid extraction using z-methyl-N-butylpyridinium tetrafluoroborate isomers (z=2, 3, or 4) at T=313.2 K. /. Ghent. Therntodyn. 42,1004-1008, ISSN 0021-9614. 

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. 

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. 

Abbreviations Ac acetyl Bn benzyl BSP 1-benzenesulfinyl piperidine BTIB bis(trifluoroacetoxy)iodobenzene DAST (diethylamino)sulfur trifluoride DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTSF dimethyl(methylthio)sulfonium tetrafluoroborate DMTST dimethyl(methylthio)sulfonium triflate DTBMP 2,6-Ai-tert-butyl-4-methylpyridine DTBP 2,6-di-tert-butylpyridine DTBPl 2,6-di-tert-butylpyridinium iodide FDCPT l-fluoro-2,6-dichloropyridinium triflate FTMPT l-fluoro-2,4,6-trimethylpyridinium triflate IDCP iodonium dicollidine perchlorate IDCT idonium dicollidine triflate LPTS 2,6-lutidinium p-toluenesulfonate LTMP lithium tetramethylpiperidide Me methyl MPBT S-(4-methoxyphenyl) benzenethiosulflnate NBS A-bromosuccinimide NIS A-iodosuccinimide NlSac A-iodosaccharin PPTS pyridinium p-toluenesulfonate TBPA tris(4-bromophenyl)ammoniumyl hexachloroantimonate Tf trifluoromethanesulfonyl TMTSB methyl-bis(methylthio)sulfonium hexachloroantimonate TMU tetramethylurea Tr trityl TTBP 2,4,6-tri-tert-butylpyrimidine. 

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