Árpád Molnár

Acidity dependence of the trifluoromethanesulfonic acid catalyzed isobutane-isobutylene alkylation modified with trifluoroacetic acid or water

Abstract Trifluoromethanesulfonic acid (TFSA) catalyzed isobutane-isobutylene alkylation modified with trifluoroacetic acid (TFA) or water, was studied over a wide range of acidity (Ho: −10.1 to −14.1). The effect of the acidity of these nonoxidizing strong mixed acid systems on the alkylation, is reported. For both systems, the best alkylation conditions were those at an acid strength of about Ho= −10.7, giving a calculated research octane number (RON) of 89.1 (TFSA/TFA) and 91.3 (TFSA/H 2 O).

Electrophilic chlorination of methane over superacidic sulfated zirconia

Catalytic chlorination of methane was studied over SO42−/ZrO2, Pt/SO42−/ZrO2, and Fe/Mn/SO42−/ZrO2 solid superacid catalysts. The reactions were carried out in a continuous flow reactor under atmospheric pressure, at temperatures below 240°C, with a gaseous hourly space velocity of 1000 ml/g h and a methane to chlorine ratio of 4 to 1. At 200°C with 30% chlorine converted the selectivity in methyl chloride exceeds 90%. At more elevated temperatures, the selectivity decreases but stays above 80% in methyl chloride at 225°C using the sulfated zirconia catalysts. The selectivity can be enhanced by adding platinum to sulfated zirconia catalysts. An iron and manganese-doped catalyst exhibited excellent selectivities at somewhat lower conversions. Methyl chloride is obtained at 235°C in selectivities greater than 85%. No chloroform or carbon tetrachloride is formed. The electrophilic insertion involves electron-deficient metal-coordinated chlorine into the methane C-H bond.

Friedel-Crafts reactions induced by heteropoly acids. Regioselective adamantyl substitution of aromatic compounds

Heteropoly acid catalyzed adamantylation of aromatic compounds (toluene, anisole, fluoro- and bromobenzene) was studied. The catalysts applied were various dodecaheteropoly acids of Keggin- type (Hn[XM12O40]; n=3, 4; X=Si, P; M=Mo, W) and some of their derivatives (Cs2.5H0.5[PW12O40] and heat-treated H4[SiMo12O40]/SiO2). The reaction in each case took place in excellent yield, however, the selectivity strongly depended on the experimental conditions applied. The para-isomer was shown to be formed under kinetic control, whereas para to meta isomerization occurred in the presence of acids with high acid strength (H0≤ -13) during longer reaction time. As a rule, strong acidity dependence was observed for the regioselectivity: the Mo- containing acids yield the para-substituted isomers with high selectivity, whereas the W-containing catalysts result in high meta/para ratios. In addition, using halobenzenes as reactants the formation of adamantane was observed as a product of reductive side reaction. This transformation was found to be significant in the presence of Mo-containing acids due to the redox character of these compounds.