Patent GB-991335-A (GB)
Title: Preparation of partially reduced transition metal bromides and iodides
IPC: C08F136/06
Filed: 1962-09-11
Abstract: A process of preparing a partially reduced transition metal bromide or iodide comprises forming a slurry of the corresponding transition metal chloride in an inert molten metal halide, the halogen portion of which corresponds to the halide to be produced, and reacting the chloride with the hydrogen halide, the halide of which corresponds to the halide to be produced. Specified transition metals are Ti, Zr, Hf, V, Cr, Nb, Mo, Ta, W, Fe, Co and Ni.  Examples relate to the production of VBr3, CrBr3, TiI3, and TiBr3.  The production of two allotropic modifications of TiBr3 is also described.  The term " partially reduced " indicates that the transition metal is in a valence state which is at least one unit below its maximum valence in combination with the particular halide.  The inert molten metal halide may be a transition metal halide, the halogen portion of which corresponds to the halide being produced, with the transition metal being in its maximum valence state, for example, TiBr4 when preparing TiBr3.  The molten metal halide may be formed in situ from the corresponding transition metal chloride simultaneously with the conversion of the partially reduced chloride to the corresponding bromide or iodide, for example, a slurry of TiCl3 in TiCl4 may be converted into a slurry of TiBr3 in TiBr4 by simultaneous halogen exchange with HBr.  The cation of the inert molten metal halide may be different from that required in the desired product, e.g. AlBr3 may be used in the preparation of TiBr2. The inert molten metal halide may also be a compound of a transition metal different from that in the partially reduced halide, e.g. TiBr4 may be used in the conversion of VCl3 into VBr3.  The partially reduced halide may be separated from the slurrying medium by distillation or preferential solubility in hydrocarbons. The upper temperature limit of the reaction does not exceed 300 DEG  C. and the lower limit is determined by the melting point of the halide used as the slurrying medium.  Pressures used may range from sub-atmospheric to 200 p.s.i.g.  In a typical example, TiBr4 and TiCl3 were heated to 39 DEG C. in a nitrogen atmosphere and dry HBr was passed through, the mixture being stirred and refluxed.  Solid TiBr3 was recovered by filtration and washed with n-heptane and xylene and dried in vacuo. Allotropic modifications are obtained by using different slurrying media.ALSO:Polybutadiene is obtained by polymerizing butadiene using conventional techniques, the catalyst employed being an aluminum alkyl together with a "partially reduced" transition metal bromide or iodide.  The term "partially reduced" indicates that the transition metal is in a valence state which is at least one below its maximum valence in combination with the particular halide.  Specified transition metals are Ti, Zr, Hf, V, Cr, Nb, Mo, Ta, W, Fe, Co and Ni.  Examples relate to the use of TiBr3, of different crystallographic forms together with Al(Et)3 and Al(Et)Cl2.  The reaction is terminated with a solution of phenyl-b -naphthylamine in isopropanol. TiF3 with Al(Et)3 using an Al/Ti ratio of 1 gives polybutadienes of M.W. 130,000-150,000 with < 85% cis-unsaturation.ALSO:Cycloolefinic butadiene dimers and trimers are obtained by polymerizing butadiene using conventional techniques, the catalyst used being an aluminium alkyl together with a "partially reduced" transition metal bromide or iodide.  The use of two allotropic modifications of TiBr3 is described, the b -form giving small yields of butadiene dimers (primarily cis, cis-cyclooctadiene-(1,5) and vinylcyclohexene) and trimers (primarily cyclo dodecatriene-(1,5,9). The formation of tr., tr., tr.,-cyclododecatriene-(1,5,9) is also reported using TiBr3(b ) as catalyst.  Higher yields of dimer and trimer, in comparison to the butadiene polymer, are obtained using CrBr3-aluminium alkyl catalysts.