Isocyanates, fluorine-containing

Polytetrafluoroethylene contains only C—C and C—F bonds. These are both very stable and the polymer is exceptionally inert. A number of other fluorine-containing polymers cU e available which may contain in addition C—H and C—Cl bonds. These are somewhat more reactive and those containing C—H bonds may be cross-linked by peroxides and certain diamines and di-isocyanates. 

Likewise, unsymmetrical fluorine containing carbodiimides are obtained from a-hydro-perfluoroisopropyl isocyanate. ... 

NASA-Langley provided a further improvement in processibility by replacing the methylenedianiline with a commercial aromatic diamine mixture that afforded even better handling characteristics (17). This type of product is formed by the reaction of formaldehyde with aniline as a precursor in isocyanate manufacture. Fluorine-containing thermoplastic polyimides and polyimides end capped with acetylene groups for cross-linking are also available as potential commercial high-temperature resins. 

The above groups contain plasticizers which have several representatives of similar chemical structure. There still are plasticizers in common use or that were invented for specific purposes. These can be grouped as follows biphenyl derivatives,calcium stearate,carbon dioxide, difurans, " fluorine-containing plasticizers, " hydroxyben-zoic acid esters, " isocyanate adducts, " " malonates, " multi-ring aromatic... 

Azides, Diazoalkanes, Diazirines, Azo-compounds, and Azines. Fluorinated alkanoyl azides have been dealt with already in other sections, mainly that concerned with isocyanates (see pp. 227,228, and 229). The azides CHFa Ns, (CFs)2C(N3) O SiMes, and (CF3)sC(Ns) O SOsO have been obtained from the reaction systems CHFsCl-NaNs-alkali-HsO-dioxan, (CF3)2CO-Me8Si N3,i and (CF3)2C(Ns) ONa-S2O5CIX (X = F or Cl), respectively. Eleven 2-azido-3,3>difluorocyclobutenes have been synthesized as indicated in Scheme 49 and converted thermally or photo-chemically into the corresponding 2,2-difluorocyclopropanes decomposition of the 1-cyano- and 1-methoxycarbonyl-cyclobutenes in the presence of electron ri( aromatics gave pyrrole derivatives. These results have been discussed in terms of the mechanistic pathways contained in Scheme SO Neber rearrangement with EtsN... 

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