Kinetics and mechanism of the thermal gas‐phase oxidation of perfluorobutene‐2 in presence of trifluoromethyl hypofluorite

Abstract

The oxidation of perfluorobutene-2 (C 4 F 8 ) initiated by trifluoromethyl hypofluorite (CF 3 OF) in presence of O 2 has been studied at 323.1, 332.6, 342.5, and 352.0 K, using a conventional static system. The initial pressure of CF 3 OF was varied between 4.8 and 23.6 Torr, that of C 4 F 8 between 48.7 and 302.4 Torr, and that of O 2 between 51.5 and 270.4 Torr. Several runs were made in presence of 325.5-451.2 Torr of N 2 . The main products were COF 2 , CF 3 C(O)F, and CF 3 OC(O)F. Small amounts of compound containing CF(CF 3 ) O C(O)CF 3 group were also formed, as detected by 13 C NMR spectroscopy. The oxidation is a homogeneous short-chain reaction, attaining, at the pressure of O 2 used, the pseudo-zero-order condition with respect to O 2 as reactant. The reaction is independent of the total pressure. Its basic steps are as follows: the thermal generation of CF 3 O• radicals by the abstraction of fluorine atom of CF 3 OF by

Synthesis of trifluoromethyl fluoroformate from trifluoromethyl hypofluorite and carbon monoxide: Thermal and catalyzed reaction

“…However, the thermal version of the reaction generated only trace amount of SF 5 C(O)F along with other products [30]. The compound (CF 3 ) 2 CFOC(O)F was also prepared earlier [10][11][12]. Compared with 1, these hypofluorites are all of lower thermal stability and decomposition and other reactions were anticipated.…”

“…Its formation by other reactions as a minor or a side product was also reported later [3][4][5][6][7][8][9]. Another two homologs in this series, CF 3 CF 2 OC(O)F and (CF 3 ) 2 CFOC(O)F, were prepared in low yield through an oxidation of CF 3 CF5 5CFCF 3 in presence of CF 3 OF [10] and a reaction between (CF 3 ) 2 CFO À Cs + and COF 2 [11,12]. These fluoroformates along with others, as a general formula of R f OC(O)F, were probably among the products of the preparation of some PFPE fluids through photochemical oxidation of hexafluoropropene and/or tetrafluoroethylene [3,4,13,14].…”

The use of perfluoroalkyl hypofluorites for an efficient synthesis of perfluorinated ethers characterized by low Ostwald coefficient

“…Perfluoroalkylhypofluorites are important intermediates utilized in the industrial process for the preparation of fluorinated key monomers like perfluoroalkylvinylethers [1] sulfonic-perfluoroalkylvinylethers [2] cyclic vinylethers monomers [3] as wall as catalyst for fluoroolefins oxidations [4]. The addiction reaction of hypofluorite to halogenated olefins has been studied in the previous years [5,6], kinetics studies of the free radical reaction in gas-phase [7] as well as in condensed phase have been analysed in detail [8,9].…”

Formation of bromodifluoroacetyl fluoride, CF2BrC(O)F, in the thermal gas-phase oxidation of bromotrifluoroethene, CF2CFBr, initiated by trifluoromethylhypofluorite, CF3OF

“…In the oxidation of CF 2 CCl 2 [4] initiated by CF 3 OF the formation of small quantities of 1,1-dichlorodifluoroethene epoxide was observed. The oxidations of perfluoropropene [7] and perfluorobutene-2 [8] Recently we have studied at 313.4 K the gas-phase oxidation of CF 2 CFBr initiated by NO 2 [9], giving CF 2 BrC(O)F as the main product, minor equivalent amounts of C(O)F 2 and C(O)FBr, and small quantities of bromotrifluoroethene epoxide and peroxynitrate, CF 2 BrCFBrO 2 NO 2 . It is a chain reaction propagated by bromine atoms.…”