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From fluoroethers with

Acetyl hypofluorite also cleaves the carbon-mercury bond which provides an easy entry to many fluoroethers. Since the electrophilic fluorine attacks the electrons of the C—Hg bond, the reaction proceeds with a full retention of configuration. Several l-fluoro-2-methoxy derivatives were prepared from the corresponding olefins271, formally accomplishing the addition of the elements of MeOF across a double bond (equation 153)272. Such reactions were also used for the fluorination of very activated aromatic compounds (equation 154)273. [Pg.670]

The case of methoxyflurane (CHjOCFjCHCl ) is similar (Fig. 9). The four Cl IPs are resolved at 11.5, 12.2, 12.4 and 13.2 eV. Comparison with the spectrum of CFj—CHClj shows that the methoxy group has a lowering effect on these IPs. It is of some interest to search for the photoelectron band which corresponds to ionization from the essentially oxygen lone pair orbital (O). Hardin and Sandorfy identified this band near 14 eV in fluoroethers and there is no reason to expect it at much lower energies for methoxyflurane. This is even more so for enflurane in which both neighbours of the oxygen atom are fluorinated. [Pg.120]

We at NASA reopened the question of learning to chain extend these fluoroether systems In consort with scientists at PCR Inc. The objective was to prepare long-chain difunctional polyperfluoroethers and investigate chain extension mechanisms, as well as to convert these materials to stable cross-linked polymers for sealant applications. The nitrile, acetylene, and isocyanate groups were considered. Each of these is capable of both trimerization reactions and dipolar cycloadditions. From this base line, one could then evoke both chain extension and cross-linking with a variety of reaction schemes. [Pg.191]

Figure 6 Indicates attempts to build elastomeric properties Into a polymer by Incorporating a fluoroether chain Into a polylmlde system (. Line 1 shows an aryl diamine polymer Intermediate prepared In a lengthy series of synthesis steps from a perfluoroalkylene ether dlcarboxyllc acid. The polymer Is prepared from the reaction of the diamine with perfluoro-hexamethylene-bis(phthalic anhydride). As expected, the polymer had excellent thermal stability, but, again. Its low-temperature properties were deficient. For example, en X + y = 0, the Tg was 130 C when x + y = 1, the Tg was 110 C and when x + y = 3, the Tg was 80 C. With this system, we are unable to achieve requisite (lialn flexibility because of a preponderance of rigid aromatic groups that Inhibit elasticity and cause a raising of the T beyond practical limits for our Intended purpose as a sealant material. The fluoroether segment Is simply too short to yield a useful low-temperature elastomer. Figure 6 Indicates attempts to build elastomeric properties Into a polymer by Incorporating a fluoroether chain Into a polylmlde system (. Line 1 shows an aryl diamine polymer Intermediate prepared In a lengthy series of synthesis steps from a perfluoroalkylene ether dlcarboxyllc acid. The polymer Is prepared from the reaction of the diamine with perfluoro-hexamethylene-bis(phthalic anhydride). As expected, the polymer had excellent thermal stability, but, again. Its low-temperature properties were deficient. For example, en X + y = 0, the Tg was 130 C when x + y = 1, the Tg was 110 C and when x + y = 3, the Tg was 80 C. With this system, we are unable to achieve requisite (lialn flexibility because of a preponderance of rigid aromatic groups that Inhibit elasticity and cause a raising of the T beyond practical limits for our Intended purpose as a sealant material. The fluoroether segment Is simply too short to yield a useful low-temperature elastomer.
It has been documented (10) that polytrlazlnes derived from perfluoroallphatlc dlnitrlles are tough and. In some cases, brittle. Thus, it is conceivable that, by mixing a fluoro-allphatic dinitrile with a long-chain fluoroether dinltrlle and subsequently polymerizing to a polytrlazlne, the resulting material would display properties intermediate between the polytrlazlnes derived from homopolymerization of the nitriles. [Pg.195]


See other pages where From fluoroethers with is mentioned: [Pg.157]    [Pg.183]    [Pg.242]    [Pg.227]    [Pg.336]    [Pg.227]    [Pg.17]    [Pg.133]    [Pg.24]    [Pg.1351]    [Pg.18]    [Pg.55]    [Pg.74]    [Pg.266]    [Pg.309]    [Pg.335]    [Pg.402]    [Pg.172]    [Pg.189]    [Pg.189]    [Pg.195]    [Pg.203]    [Pg.265]    [Pg.189]   


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Fluoroether

Fluoroethers

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