Patent GB-998746-A (GB)
Title: Catalysts for polymerization of ethylene and methods of using them
IPC: C08F10/00
Filed: 1963-07-17
Abstract: Bis-arene-chromium compounds represented by the general formula [(Y)2Cr]n+Xn-, wher [(Y)2Cr]+ denotes a bis-arene-chromium cation containing a hydrocarbon Y selected from benzene, biphenyl, and their alkyl substitution products, Xndenotes an anion which forms a salt with the cation, and n is an integer of at least 1, equal to the number of the electric charge of the anion, are used as components of a polymerization catalyst.  The preparations of the following chromium compounds are described, i.e. (1) bis-biphenyl chromium chromate, by reacting for 10 minutes at 140 DEG  C. biphenyl, AlCl3, chromium chloride, and Al powder, hydrolysing the product at a pH around 7-8, unreacted substance and reaction product residues and then reacting the so-formed bisdiphenyl chromium hydroxide in aqueous solution with potassium chromate to form compound (1) as a precipitate and recovering same (2) bis-biphenyl chromium-dichromate is formed by reacting an aqueous solution of bis-biphenyl chromium hydroxide prepared as in (1), with potassium bichromate, and recovering (2) as a powder, and (3) bis-biphenyl chromium-tetra-thiocyano - diammono - chromate is made by reacting an aqueous solution of bis-biphenyl chromium hydroxide prepared as in (1), with Reinecke's salt NH4[(NH3)2Cr(CHS)4] 1/2 H2O, thereby precipitating (3), which is recovered by filtration and recrystallized from acetone-ether.ALSO:A polymerization catalyst for ethylene comprises (1) a bis-arene-chromium compound represented by the formula [(Y)2Cr]n\sJX\sK wherein [(Y)2Cr]\sJ is a bis-arene-chromium cation and Y is a hydrocarbon selected from benzene, diphenyl, and derivatives ring-substituted by alkyl, Xn\sK represents an anion which forms a salt with the cation, and n is an integer of at least 1, and which is equal to the number of electric charges on the anion, and (2) an organometallic compound or a halogen-containing organometallic compound of Group I, II and III, of the Periodic System.  In the catalyst the ratio of components (1) : (2) is from 1 : 2 to 1 : 300.  Y may be benzene, toluene, xylene, ethylbenzene, cumene, mesitylene, or diphenyl.  The anion may be iodide, perchloric, picric acid (O.C6H2(NO2)3)-, thiocyanic ions, chromic, bichromic, tetrathiocyano-diammonochromic acid ion, tetrathiocyano-dianilinochromic acid ion, and tetraphenyl-boric acid ion (B(C6H5)4)-. Exemplified components (1) are bis-diphenyl chromium iodiode, bis-diphenylchromium - tetrathiocyano - diammonochromate, bis - diphenyl chromium thiocyanate, bis - benzene - chromium iodide, bis - toluene - chromium iodide, bis-mesitylene or benzene chromium - tetrathiocyano - diammonochromate, bis - diphenyl - chromium chromate or dichromate, and bis - benzene - chromium tetrathiocyanodianilin - chromate.  Component (2) may be aluminium triethyl, aluminium triisobutyl, magnesium diethyl, or lithium butyl. The polymerization is effected in an inert solvent or diluent such as benzene, toluene, xylene, n-heptane, ligroin, n-hexane, trichloroethylene, or chlorobenzene.  The catalyst is generally formed in situ, and the polymer recovered by conventional techniques, e.g. addition of methanol.