Butyl hexafluoroantimonate

In organic chemistry XPS spectra gave a direct evidence for a classical carbonium ion in r-butyl-hexafluoroantimonate (III) with a chemical shift... 

Replacing an a-alkyl snbstituent by an a-aryl group is expected to stabilize the cationic center by the p-Jt resonance that characterizes the benzyl carbocations. In order to analyze such interaction in detail, the cumyl cation was crystallized with hexafluoroantimonate by Laube et al. (Fig. 13) A simple analysis of cumyl cation suggests the potential contributions of aromatic delocalization (Scheme 7.3), which should be manifested in the X-ray structure in terms of a shortened cationic carbon—aromatic carbon bond distance (C Cat). Similarly, one should also consider the potential role of o-CH hyperconjugation, primarily observable in terms of shortened CH3 distances. Notably, it was found experimentally that the Cai distance is indeed shortened to a value of 1.41 A, which is between those of typical sp -sp single bonds (1.51 A) and sp -sp double bonds (1.32 A). In the meantime, a C -CH3 distance of 1.49 A is longer than that observed in the tert-butyl cation 1 (1.44 A), and very close to the normal value for an sp -sp single bond. 

Typical alkylation reactions are those of propane, isobutane, and n-butane by the ferf-butyl or sw-butyl ion. These systems are somewhat interconvertible by competing hydride transfer and rearrangement of the carbenium ions. The reactions were carried out using alkyl carbenium ion hexafluoroantimonate salts prepared from the corresponding halides and antimony pentafluoride in sulfuryl chloride fluoride solution and treating them in the same solvent with alkanes. The reagents were mixed at —78°C warmed up to — 20°C and quenched with ice water before analysis. The intermolecular hydride transfer between tertiary and secondary carbenium ions and alkanes is generally much faster than the alkylation reaction. Consequently, the alkylation products are also those derived from the new alkanes and carbenium ions formed in the hydride transfer reaction. 

A hydrophobic IL, 1-butyl-3-decylimidazolium hexafluoroantimonate [dbim][SbF6], was then chosen for particle impregnation, thus creating a lipophilic environment around the particle where reactions can take place. Thus, 42 is added to a solution of dbim SblvJ in ethyl acetate to give, after solvent removal under reduced pressure, a fine powder of SiO2-Sc-IL (43). 

Current photoresists cannot be used for 157 nm technology, mainly because their transmittance at 157 nm is too low. Although materials with aromatic substructures are quite useful for the 248-nm process, only purely aliphatic polymers are employed in the current 193 nm technology. For an illuminating wavelength of 157 nm, even the absorptivity of most aliphatic compounds is too high. Therefore, only partially fluorinated polymers with absorption characteristics carefully optimized by experiment [10] and molecular modeling [11] can be used. The solubility switch after illumination is usually achieved by addition of a photo-activatable super-acid (e.g. a diaryl iodonium hexafluoroantimonate) [12], which typically cleaves an add-labile tert-butyl ester in the polymer (Scheme 4.9). 

As an example, when the photoacid generator triphenylsulfonium hexafluoro-antimonate is exposed to radiation, it decomposes to release the superacid hexafluoroantimonic acid in the resist film. While this photochemical reaction can occur at room temperature, the acid-catalyzed deprotection of the pendant t-butyl group of the resist polymer occurs at reasonable rates only at elevated temperature. It is therefore necessary to heat the resist film to an appropriate temperature (PEB) to provide the energy that is required for the acid-catalyzed deprotection of the t-butyl group of the ester, which in mrn affords the base-soluble norbomene carboxylic acid unit the isobutylene volatilizes. The extent of deprotection at constant temperamre is dependent on the dose of applied radiation. By monitoring the carboxylic acid OH stretch 3000-3600 cm and the ester carbonyl (C O) around 1735 cm acid carbonyl (C O) around 1705 cm , and ester (C-O-C) stretch around 1150 cm it is possible to determine by means of IR spectroscopy the extent of dose-dependent deprotection, as well as the influence of baking temperature on the extent of deprotection for each resist system. Doses ranging from 0 to 50 mJ/cm were applied to each resist system, after which they were baked at 120, 130, 140, and 150°C for 60 seconds and analyzed by FTIR. ... 

When the photoacid generator, triphenylsulfonium hexafluoroantimonate, is exposed to radiation, it decomposes to release the super acid, hexafluoroantimonic acid, in the resist film. While this photochemical reaction can occur at room temperature, the acid-catalyzed deprotection of the pendant r-butyl group of the resist polymer occurs at reasonable rates only at elevated temperature. It is therefore necessary to heat the resist film to an appropriate temperature (postexposure bake) to provide the energy that is required for the acid-catalyzed deprotection of the r-butyl group of the ester, which in turn, affords the base-soluble norbomene carboxylic acid unit isobutylene volatilizes. The extent of deprotection at constant temperature is... 

Oxman et al., smdied controlled, sequentially curable cationic/free radical hybrid photopolymerization of diepoxide/acrylate hybrid material with the aid of photodifferential scanning calorimetry. The polymerizations were carried out in the presence of various concentrations of either ethyl-4-dimethylamino benzoate or 4-tert-butyl-N,N,-dimethylaniline as electron donors and camphoquinone/diphenyliodonium hexafluoroantimonate as the sensitizing system. The results showed that the free-radical acrylate reactions always precede the cationic epoxy polymerizations. 

Friedel-Crafts reaction of pyrrole can be achieved without Lewis acid/base catalysts when the reaction is performed using ionic liquids as cosolvent. Regioselective alkylation of pyrrole with simple alkyl halides and mesylates using [bmimJlSbFg] (1-n-butyl-3-methylimidazolium hexafluoroantimonate) as cosolvent proceeds to deliver the monoalkylated pyrrole as the major product when excess pyrrole (10 equiv) is used (eq 8). 

Dzyuba Bartsch, 2002 Tsunashima Sugiya, 2007), except for l-butyl-3-methylimidazolium hexafluorophosphate ([BMImJpFe], Wako Pure Chemical) and 1-butyl-3-methylimidazolium hexafluoroantimonate ([BMIm][SbF6], Fluka), which were used as received. Before the measurements, the ILs were dried in vacuo, typically at approximately 315 K for 36 h. The details of these sample ILs have been described elsewhere (Shirota Castner, 2005 Shirota et al., 2009 Shirota et al., 2010). The ILs and their abbreviations are as follows. l-MethyI-3-neopentyIimidazoIium bis(trifIuoromethylsulfonyI)amide ... 

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