Trifluoromethyl Fluoroformyl Trioxicarbonate, CF₃OC(O)OOOC(O)F: The First Nonsymmetric Acyl Trioxide

Abstract

This paper reports for the first time the synthesis and characterization of trifluoromethyl fluoroformyl trioxicarbonate, CF(3)OC(O)OOOC(O)F. The new trioxide is obtained from the gas-phase photolytic reaction of CF(3)C(O)OC(O)CF(3) and FC(O)C(O)F at 223-228 K. It is a very thermally labile molecule that decomposes at room temperature by rupture of either of the CF(3)OC(O)O-O-OC(O)F bonds. These bonds are nonequivalent, and a branching ratio of 0.8 for fragmentation through the CF(3)OC(O)OO-OC(O)F bond was obtained. Unambiguous identification was possible through reaction of the trioxide with an excess of NO(2). Potential-energy surfaces (PES) of the different rotamers were studied by the B3LYP/6-311+G* method, and analysis of the IR frequency of the possible mixture of rotamers agrees excellently with the experimental IR spectrum. This molecule is the first nonsymmetric acyl trioxide reported in the literature.

Theoretical study of the molecular conformations, vibrational frequencies and thermochemistry of the FC(O)OOO(O)CF, FS(O2)OOO(O2)SF and FC(O)OOO(O2)SF trioxides

“…Previous kinetic studies have lead to a OAO bond dissociation energy of 30.3 ± 0.2 kcal mol À1 [3]. Other fluorinated open-chain trioxides more recently synthesized, isolated and characterized are CF 3 OC(O)OOO(O)COCF 3 and CF 3 OC(O)OOO(O)CF [4,5]. The first was proved thermally stable up to 243 K and decomposes with a half-life of 1 min at room temperature.…”

Synthesis and properties of trifluoromethoxyl fluoroformyl anhydride, CF3OC(O)OC(O)F

“…The complete method of synthesis for the parent trioxide is described elsewhere [10]. Briefly, it is obtained from the 266 nm photolysis of trifluoroacetic anhydride (CF 3 C(O)OC(O)CF 3 ) and oxalyl fluoride (FC(O)C(O)F) in excess of CO and O 2 at about 223 K. Once the asymmetric trioxide is formed, the lamp is turned off and the reactor bath is cooled down to about 193 K. At this temperature the trioxide sticks on the reactor walls and the remaining products and starting materials such as CF 2 O, CO 2 , CF 3 C(O)F, CF 3 OOCF 3 , FC(O)OOC(O)F, CO, and O 2 can be pumped out.…”