ChemInform Abstract The title compounds are prepared from the corresponding chlorides or BBr3 and CF3SO3H, isolated in pure form and fully characterized (elemental analysis, mol. wt., NMR and IR spectroscopy) (no yields given). B triflate is a monomeric, relatively volatile compound, whereas Al and Ga triflate are associated, high-melting solids. All three triflates are efficient new Friedel-Crafts catalysts as shown in alkylation, isomerization, and acylation reactions. Alkylation of benzene and toluene with alkyl halides (alkyl: Me, Et, iPr, tBu; halide: F, Br, Cl) are carried out with the triflates as catalyst in CH2Cl2 and MeNO2 at room temperature. Substrate and positional selectivity (isomer distribution) are determined by GLC. B triflate shows the highest catalytic activity followed by Ga and Al triflate as reflected by overall yields in the alkylation reactions and tendency of accompanying isomerization, causing substantially increased meta substitution and disproportionation.

Abstract-A new filter structure using admissible wavelet packet analysis is presented. These filters have the advantage of having frequency bands spacing similar to the Mel scale. Further wavelet packet transform's multiresolution capabilities are used to derive new sets of features, which are found to be superior to Mel frequency cepstral coefficients (MFCC) in unvoiced phoneme classification problem.

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