The comparison of thermal stability of some hydrofluoroethers and hydrofluoropolyethers

• Published in: Journal of fluorine chemistry Vol. 125; no. 7; pp. 1081 - 1086
• Main Authors: Marchionni, G, Petricci, S, Guarda, P.A, Spataro, G, Pezzin, G
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2004
• Subjects: Hydrofluoroethers; Hydrofluoropolyethers; Thermal stability; Hydrofluoroethers; Hydrofluoropolyethers; Thermal stability
• ISSN: 0022-1139; 1873-3328
• DOI: 10.1016/j.jfluchem.2004.01.027

The thermal stability of several representative hydrofluoropolyethers (HFPEs) and hydrofluoroethers (HFEs) with the general formula R fOC xH yF z, (were x = 1 or 2, z = 0 or 2 and R f is respectively a perfluoropolyether or a perfluoroalkyl moiety), has been investigated and products and mechanisms of the main degradation reactions have been reported. The observed stability order is correlated with the chemical nature of the chain ends: in particular, the OCF 2H terminated compounds show a higher stability compared with the OCH 3 and OC 2H 5 terminated hydrofluorocompounds. The thermal stability of representative hydrofluoropolyether (HFPE) and hydrofluoroether (HFE) compounds has been evaluated. The observed stability order appears to be correlated with the nature of the hydrogenated chain ends; in particular, molecules having fully hydrogenated chain ends (OCH 3 and OC 2H 5) show a significantly lower stability compared with the OCF 2H terminated compounds. The main degradation products suggest, however, that the same primary reaction is responsible for the decomposition of all the compounds examined; this reaction involves the fragmentation of the R fOC x H y F z bond with fluorine transfer between the two carbon atoms close to the oxygen, leading to the formation of a hydrofluorocarbon C x H y F ( z+1) and an acyl fluoride or a ketone.