The present invention relates to mixtures comprising from 70 to 99.5% by weight of a compound of the formula (R)4P+X− (1) and from 30 to 0.5% by weight of a compound of the formula (R)3P═O (2), where R is in each case a radical and X− is an inorganic or organic anion or the equivalent of a multiply charged inorganic or organic anion, also to a process for preparing the mixtures by reacting a phosphorus pentahalide with pyrrolidine or piperidine in the molar ratio 1:6 to 1:50 in the presence of an inert solvent initially at −20 to 80° C., subsequently continuing the reaction at 90 to 180° C., treating the resulting reaction product at 0 to 80° C. with aqueous alkali at a pH of 7 to 15, and separating aqueous and organic phase from one another, and to the use of the mixtures as catalyst and cocatalyst for phase-transfer reactions, nucleophilic substitution reactions or halogen-fluorine exchange reactions.