Perfluoro ether

Other interesting perfluoro ether stmctures can be obtained by copolymerization of hexafluoroacetone with ethylene oxide, propylene oxide, and trimethylene oxide with subsequent fluorination to yield the following stmctures (67) ... 

Cyclic ethers having perfluorinated side chains or perfluorinated rings attached in the a-position with respect to oxygen are remarkably stable toward cobalt trifluoride and can be successfully fluormated to perfluoro ethers at 440 °C without being cleaved to a considerable extent at the oxygen [16, 17], Selected examples are shown in Table 4. 

Table 4. Selected Examples of Preparation of Perfluoro Ethers [16, 17] by Heating with Cobalt Trifluoride and Calcium Fluoride at 440 "C...

Irradiation at 20 C of perfluoro ethers containing a carbonyl group causes almost quantitative decarbonylation [179. Azindine undergoes photochemical addition with methyl trifluoroacetate [180 (equation 47). 

It has been determined using ll,FNMR that some of the perfluoro ethers and other per-fluorocarbon compounds synthesized with this process have residual hydrogen remaining on the organic compound in concentrations below 3 parts per billion. To put that in perspective, in polytetrafluoroethylcne which is made from tctrafluorocthcne monomer, the hydrogen content is several parts per million. 

If the following scheme is used to classify the perfluoro ethers,... 

A,C(j-Diacyl-substituted perfluoro ethers react in a similar way (70). 

Some of the following work was performed with a view to synthesis of perfluoro—ethers and —polyethers, which is not the subject of this present discussion, but we were interested in the relative reactivities of various sites in ether systems. Hence the following results are revealing. 

Tiers, G.D. The chemistry of perfluoro ethers. II. Ether cleavage with simultaneous replacement of a-fluorine by chlorine. J. Am. Chem. Soc. 1955, 77, 6703-6704. 

Toy, M.S. Stringham, R.S. Some new perfluoro ethers and copolymers from Dewar hexafluorobenzene. 1. Fluorine Chem. 1979,13(1), 23-39. 

Patent literature concerning synthesis of fluoro-ethers possessing anaesthetic properties is dealt with in the appendix to this chapter (p. 303) on another medical note, the use of perfluoro-ethers as oxygen-transport agents in artificial blood, etc, continues to be investigated (see also pp. 12,207). Also available for consultation are papers that deal with (i) synthesis of alkyl 2,2,2-trifluoro-l-halogenoethyl ethers from chloral CClg CHO + HF (over hot Cr oxyfluoride) CFs CHO, HF [with (RO)4Si or ROH and SiCU] CFs CH(OH) OR CFs-CHCl-OR [with... 

Morita, M. Kawasaki, T Yoshrmoto, N. Ishikawa, M., Nonflammable oiganic electrolyte solution based on perfluoro-ether solvent for lithium ion batteries. Electrochemistry 2003, 71, 1067-1069. 

A commercial grade of a tetrafunctional epoxy resin (TGDDM) was modified by the addition of a perfluoro-ether oligomer to improve the toughness. The cure characteristics of a typical composition of this mixture were investigated by in situ FT-NIR spectroscopy. The presence of the, fluoro-oligomer induced a two-fold reduction of the initial curing rate [101]. 

Musto, R, et al., Cnre Kinetics and Ultimate Properties of a Tetrafunctional Epoxy Resin Tonghened by a Perfluoro-Ether Oligomer. Polymer, 2001. 42 5189-5198. 

Figure 5.313 shows the stress-crack initiating effect of non-additivated, chemically differently structured lubricant oils. Poly-a-olefins, silicone oils, and perfluoro-ether oils have a strong stress-crack initiating effect. Ester oils and polyglycols (soluble and insoluble in water) counteract stress-cracking [965]. 

Each perfluoro macrocycle was ionized to form M then allowed to react with 02to successfully form + O2) adducts (11). lon/molecule reactions involving an acyclic perfluoro ether and hydrogenated crown ethers were also examined to determine whether the cyclic and/or perfluoro nature of the macrocycles played a role in the formation of the (M + O2)" adducts. Neither the perfluoro acyclic analog nor hydrogenated crown ethers reacted with 02to form (M + O2)" adduct ions. This result confirmed that the macrocyclic nature of the perfluoro crown ethers enhanced their ability to bind O2. 

The ability to form and characterize new types of macrocyclic ion complexes involving perfluoro ethers holds great promise for future studies of host-guest complexation in the gas phase. Comparisons to the gas-phase chemistry of hydrogenated macrocycles may allow further insight into the influence of thermochemical and structural properties on the binding interactions of host molecules. All of the perfluoro crown ethers and perfluorocryptands to date have been found to coordinate 02 and F as well as some otii c anions (24). 

Figure 15. The superposition of the carbon and oxygen atoms of the perfluoro -cis-syn-cis-dicyclohexyl[18]crown-6 ether (solid lines) onto the equivalent atoms of perfluoro [18]crown-6 ether (dashed lines) illustrating the similar configuration of the perfluoro ether rings of the two structures.

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