Patent GB-689425-A (GB)
Title: Improvements in or relating to substituted fluorocarbon compounds
Filed: 1951-03-08
Abstract: Polyvinyl alcohol is reacted with 1,1-dihydroperfluoroalkyl isocyanates of the formula CnF2n+1CH2N : C : O, where n has a value from 1 to 17 or the corresponding carbamyl chlorides.  The products are fluorinated polyvinyl carbamates (urethanes) having N-bonded side chains with terminal perfluoroalkyl radicals.  The products are water-repellent and can be used for coating cloth, paper and cellulosic films.  The preparation of the isocyanates and carbamyl chlorides is described (see Group IV (b)).ALSO:The invention comprises 1,1-dihydroperfluoroalkyl isocyanates of the formula CnF2n + 1CH2N : C : O, where n has a value from 1 to 17 and the corresponding carbamyl chlorides represented by the formula CnF2n + 1CH2NHCOCl.  The isocyanates are obtained by reaction in an inert solvent, of phosgene with the corresponding amine of formula CnF2n + 1CH2NH2.  The reaction is commenced at about 0 DEG  C., followed by gradual heating. The carbamyl chloride is formed as a precursor of the isocyanate and can be recovered as such from the reaction mixture.  The isocyanate is re-converted to carbamyl chloride by reaction with anhydrous hydrogen chloride.  The products react with amines to give ureas.  With water bis-ureas also result.  The compound CF2CH2N : C : O yields CF3CH2NH.CO.NHCH2CF3.  The urea C3F7CH2NH.CO.NH.CH2C3H7 is obtained similarly.  The isocyanates also react with polyvinyl alcohol to give fluorinated polyvinyl carbamates which are water-repellent and are suitable for coating cloth, paper, and cellulosic films.  The isocyanates themselves may also be used for such purposes and also for fireproofing.  In examples there are prepared from the corresponding amines by the above methods: (1) 1,1-dihydrotrifluoro ethyl isocyanate (CF3CH2N : C : O); (2) 1,1 - dihydropentafluoropropyl isocyanate (C2F5CH2N : C : O).  With water this gives the urea C2F5CH2.NH.CO.NH.CH2C2F5; (3) 1,1-dihydroheptafluorobutyl isocyanate (C3F7CH2N : C : O).  Hydrogen chloride may be removed from the product by heating with tetraphenyl tin.  The product is converted to the carbamyl chloride C3F7CH2NHCOCl by reaction with hydrogen chloride; (4) 1,1-dihydrononadecafluorodecyl isocyanate (C9F19CH2N : C : O).  Wit water this gives the urea C9F19CH2NHCO.NHCH2C9F19. With aniline there results the urea C6H5NHCO.NHCH2C9F19  The amines employed as starting materials are obtained by reduction with lithium aluminium hydride of the amides CnF2n + 1CONH2 obtained by ammonolysis of the fluorocarbon acid fluorides CnF2n + 1COF. The latter are obtained by electrolysis of an anhydrous hydrogen fluoride solution of the corresponding carboxylic acid CnH2n + 1COOH at a cell voltage insufficient to generate free fluorine.  Details are given of the reduction of the corresponding amides to give compounds of formul  C3F7CH2NH2 (isolated as the bisulphate followed by distillation); C2F5CH2NH2 (extracted with ether from the sulphuric acid solution); CF3CH2NH2 (tetrahydrofuran is the solvent during the reaction); and the compound C9F19CH2NH2 (isolated as the hydrochloride and the latter distilled).