Cationic Oligomerization of 3-Methyl-1-Butene Catalyzed by BF3- Protonic Donor Complexes

The oligomerization of 3-methyl-1-butene was carried out in the presence, as catalysts, of BF3 complexes with different protonic donors (CH3OH, H2O, CH3CH2COOH, H3PO4) in a 1:1 molar composition. By working in n-hexane solution at temperatures between 0 and 70°C only unsaturated low MW oligomers (dimers to hexamers) were obtained. Each oligomer was a complex mixture of isomeric olefins as revealed by GLC and GLC-MS analysis. The presence of some fragmentation products containing one carbon atom more or less than the oligomer was pointed out. The results obtained show that the MW of the oligomers decreases by increasing the acidity of the protonic donor used as complexing agent of BF3. By increasing the temperature a decrease of the MW and an increase of the presence of fragmentation products was obtained.