GB910227A - Polymerization of diolefins - Google Patents

Abstract

Conjugated diolefins are polymerized or copolymerized with other ethylenically unsaturated compounds in the presence of a catalyst comprising the reaction product of (A) a lithium arylide of a fused ring or contiguous ring aromatic hydrocarbon with (B) titanium trichloride, said titanium trichloride being present in amount such that the ratio of gram atoms of lithium to gram mols. of titanium trichloride is between 0,07 and 3,0. Specified diolefins are isoprene, butadiene, 2-methyl-1,3-pentadiene, 2,3-dimethyl butadiene and cyclopentadiene. Specified polynuclear aromatic hydrocarbons are naphthalene, anthracene, chrysene, biphenyl, fluorene, triphenylene, naphthacene and phenanthrene; preferred catalyst components being lithium naphthalenide and dilithium biphenylide. The titanium trichloride may be in the form of a complex with lithium and aluminium trichloride. Specified comonomers are styrene and a -methylstyrene. Polymerization may be effected in the presence of solvents, e.g. propane, pentane, hexane, heptane, dodecane, cyclopentane, cyclohexane, methyl cyclohexane and benzene. The monomer may be purified by refluxing with sodium or other alkali metal sand followed by distillation. The solvents may be purified by dehydration with silica gel, alumina or calcium chloride followed by distillation. Catalyst destruction and polymer stabilization may be effected by adding a solution of an antioxidant, e.g. phenyl-b -naphthylamine, in methanol or isopropanol. The products have predominantly cis-1,4 structure and may be used as substitutes for Hevea rubber in tyres, air springs, torsion bushings and tubing.ALSO:Arene lithium compounds may be prepared by mixing or grinding lithium with fused ring or contiguous ring aromatic hydrocarbons. Specified hydrocarbons are naphthalene, anthracene, chrysene, biphenyl, fluorene, triphenylene, naphthacene and phenanthrene. Examples describe the preparation of (1) naphthalene lithium by mixing a dispersion of lithium in petrolatum with naphthalene and (IX) biphenyl di-lithium by grinding lithium foil with biphenyl. The compounds may be used in the preparation of polymerization catalysts.