Preparation and conformational properties of the perfluoro diether CF(3)OCF(2)OCF(2)C(O)F, a model molecule to study properties of perfluoro polyethers.
The compound CF(3)OCF(2)OCF(2)C(O)F was prepared by oxidation of hexafluoropropene with molecular oxygen in the gas-phase using CF(3)OF as initiator. (13)C NMR, FTIR, Raman, UV-vis, and mass spectra were obtained and interpreted. The theoretical structure studies were performed by the calculation of the potential energy surfaces, using the results obtained for a smaller related molecule, CF(3)OCF(2)C(O)F, as a starting point. A high degree of conformational flexibility of this compound is evidenced by the values of several conformations, varying within the range of 1 kcal/mol. Theoretical calculations predict chain conformations as the most stable molecular forms, as expected from the presence of the anomeric effect. The experimental fundamental vibrational modes are compared with those obtained theoretically, using ab initio and density functional theory methods, HF/6-31+G and B3LYP/6-31+G, respectively. The density of the compound at ambient temperature (delta = 1.7(1) g/mL), its melting point (mp = -140(5) degrees C), its boiling point (bp = 14.5 (1) degrees C), and the relation between its vapor pressure and the absolute temperature (ln P = 13.699 - 2023.4/T) were also determined.
Romano
R M
RM
CEQUINOR (CONICET-UNLP) and Laboratorio de Servicios a la Industria y al Sistema Científico (UNLP-CIC-CONICET), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, (1900) La Plata, Argentina.
Czarnowski
J
J
Della Védova
C O
CO