Teruo Takakura

Synthesis of fluorinated difunctional monomers

Abstract In order to obtain fluorinated difunctional monomers for fluoropolyurethanes, we synthesized novel fluorinated aliphatic diisocyanates [OCNCH 2 (CF c2 ) n CH 2 NCO] from corresponding diols [HOCH 2 CH 2 (CF 2 ) n CH 2 CH 2 OH]. Oxidation of the diols with chromium trioxide-sulfuric acid gave α, α, ω, ω-tetrahydroperfluoroalkylene dicarboxylic acids in high yields. Then treating the acids with phosphorus pentachloride afforded corresponding dicarboxyl chlorides, which are easily converted to dicarboxyl azides with hydrazoic acid-pyridine complex. Finally, on Curtius rearangement of the azides, the end products, α, α, ω, ω-tetrahydroperfluoroalkylene diisocyanates were obtained in 53% (n=4) and 19% (n=6) yields from the starting diols.

Synthesis of Fluorinated Dicarboxylic Acids and Their Derivatives.

New fluorinated dicarboxylic acids, 3, 3, 4, 4, 5, 5, 6, 6-octafluorooctanedioic acid [2 a] and 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8-dodecafluorodecanedioic acid [2 b], having a methylene group between perfluoroalkylene and each carboxyl group, were synthesized in high yields, by the oxidation of corresponding diols[1] with CrO3/H2SO4 (Jones reagent). Oxidation of [1] with other oxdizing reagents such as nitric acid and KMnO4 did not virtually give[2].These dicarboxylic acids are useful not only as monomers of fluorinated polycondensation polymers, but also as precursors of other difunctional monomers such as bis(carboxyl chlorides)[3]and diisocyanates [4].