When saturated with boron trifluoride, certain polyhydric alcohols form adducts which catalyze reactions for which boron trifluoride is catalytic. The adduct is recovered from the reaction mixture and recycled, greatly reducing boron and fluoride values in the product and in any effluent. Examples include propylation of toluene in the presence of a recycled adduct of boron trifluoride with mannitol or sorbitol.
