Conductometric Investigation of Complexes of Trifluoroacetic Acid with Hexaoxa-“ Crown ” Ethers

Abstract

The complexation of trifluoroacetic acid with two hexaoxa-“crown” ethers (18/CR/6 and DCC/A) in 1,2-dichloroethane was investigated conductometrically. The equilibrium constants of complex formation are of the same order of magnitude for the two ethers investigated (∼1.9 × 103 and ∼0.9 × 103 dm3 mol–1, respectively).

Triple ions seem to represent the dominant species responsible for the high conductivity of the investigated systems. The overall ionization constant was found to be higher for the DCC/A than for the 18/CR/6 complex.

The conductivity of the investigated solutions was found to be adversely affected by the addition of small amounts of water. This unusual behaviour has been attributed to the fact that the hydrate of the complexed acid cannot participate in the formation of triple ions.