PRODUCTION OF 3-METHYL-1-BUTENE

1,192,578. Olefins. PHILLIPS PETROLEUM CO. 18 Sept., 1967 [19 Sept., 1966], No. 42409/67. Heading C5E. 3-Methyl-1-butene is prepared by catalytically dimerizing propylene to obtain at least some 4- methyl-2-pentene, which is then contacted with ethylene in the presence of an olefin disproportionation catalyst to produce 3-methyl-1-butene as desired product and propylene, which may be recycled to the dimerization. Other products of the dimerization may be treated as follows. 4-methyl-1-pentene may be recovered as product by fractionation, or may be isomerized to 4-methyl-2-pentene which is fed to the disproportionation. 2 - Methyl - 2 - and - 1 - pentenes may be recovered as products by fractionation and, either removed from the process, or may be isomerized to additional 4-methyl-2-pentene which is fed to the disproportionation. Suitable catalysts for the various reactions are: Dimerization: tripropyl aluminium, Na/K alloy, or #-allyl nickel iodide/triphenyl phosphine/ethyl aluminium dichloride. Disproportionation: an oxide of Mo, W or Re, or a hexacarbonyl or sulphide of W or Mo, any of which may be supported on SiO 2 , Al 2 O 3 , SiO 2 /Al 2 O 3 , MgO/TiO 2 , ZrO 2 , ThO 2 , AlP0 4 or ZrP0 4 , and may contain additives such as CoO or K 2 C0 3 . Isomerization: MgO, Al 2 O 3 , SiO 2 , CoO, FeO or MnO. Unconverted reactants or undesired products from any stage of the process may be recycled to any other appropriate stage.