Patent GB-795514-A (GB)
Title: Polymeric materials and the preparation thereof
IPC: C08F136/16
Filed: 1955-11-04
Abstract: The preparation of fluoro-1,3-dienes and of fluoropropenes is described.  In examples: (1) 1,1 - difluoro - 3 - methylbutadiene is prepared by adding dibromodifluoromethane to isobutene to produce the adduct: <FORM:0795514/IV (b)/1> and then dehydrobrominating at 150 DEG  C. in the presence of tri-n-butylamine; (2) 1,1,2-tri-fluorobutadiene is prepared by adding di-bromodifluoromethane to 1-fluoropropene to produce the adduct CF2BrCHFCHBrCH3 and then dehydrobrominating. The 1-fluoropropene is prepared by brominating 1-chloropropene, treating the product with hydrofluoric acid and mercury oxide in a sealed bomb and then with zinc and n-propanol; (3) 1,1,3-trifluorobutadiene is prepared by adding dibromodifluoromethane to 2-fluoropropene to produce the adduct CF2BrCH2CFBrCH3 and then dehydrobrominating at 150 DEG  C. in the presence of tri-n-butyl amine.  The 2-fluoropropene is prepared by treating 1,2-dichloropropane with potassium hydroxide, the product with hydrofluoric acid and this product with potassium hydroxide in 95 per cent alcohol; (4) 1,1,2,4,4-pentafluorobutadiene is prepared by adding 1-chloro-1,2-dibromo - 1,2,2 - trifluoroethane to vinylidene fluoride and dehydrobrominating the resulting adduct CF2BrCFClCH2CF2Br with potassium hydroxide followed by debromochlorination using zinc; (5) 1,1,2,4,4-pentafluoro-3-methyl-butadiene is prepared by adding 1,2-dichloro-2-iodo - 1,1,2 - trifluoroethane (from CF2 = CFCl and ICl) to 1,1-difluoropropane to give the adduct CF2ClCFClCH(CH3)CF2I, which is treated with potassium hydroxide and dechlorinated using zinc in propanol. The 1-1-difluoropropene is prepared by dechlorinating 1,1,2 - trichloropropane with potassium hydroxide in propanol, treating with hydrofluoric acid in a sealed tube at 150 DEG C. and dihydrochlorinating the product with potassium hydroxide in ethanol; and (6) 1,1,3-trifluoro-2-methyl-1,3-butadiene is prepared by adding dibromodifluoromethane to 2-fluorobutene-2 to yield the adduct CH3CFBrCH(CH3)CF2Br which is dehydrobrominated at 150 DEG  C. in the presence of tri-n-butyl amine. Specification 795,513, [Group IV (a)], is referred to.ALSO:The invention comprises a homopolymer of a compound of the formula: <FORM:0795514/IV (a)/1> in which Y1 and Y2 are hydrogen, fluorine or alkyl radicals having from 1-3 carbon atoms, Y1 not being the same as Y2, Y3 and Y4 are both hydrogen or both fluorine, Y1 not being hydrogen when Y3 and Y4 are fluorine. Specified homopolymers are those of 1,1,3-trifluorobutadiene, 1,1,2,4,4 - pentafluorobutadiene, 1,1-difluoro-3-methyl-, 1,1,3-trifluoro-2-methyl-and 1,1,2,4,4 - pentafluoro - 3 - methyl - butadiene.  The polymerization may be effected in mass, suspension, emulsion or solution using as promoter a peroxy compound such as cumene, diisopropylbenzene, t-butylisopropyl, triisopropylbenzene, methylcyclohexane, and t-butyl hydroperoxides, t-butylbenzoate, and trichloroacetyl, di- or trifluoroacetyl, 2,4-dichlorobenzoyl, chloroacetyl, perfluoropropionyl, acetyl benzoyl, lauroyl, and di-t-butyl peroxides, while redox systems using as oxidant sodium, potassium or ammonium persulphate and as reductant sodium or potassium bisulphite or metabisulphate may be used, in the presence of metal salts, e.g. ferrous sulphate or nitrate.  Emulsifying agents which may be present include the potassium or sodium salt derived from saturated aliphatic acids or from polyfluorocarboxylic acids and the perfluorochlorocarboxylic acids described in Specification 795,513.  Specified solvents are carbon tetrachloride, benzene and t-butyl alcohol.  The polymerization temperature range may be from - 30 DEG  to 150 DEG  C.