Process for selective hydrogenation of conjugated diolefin polymers
AssigneeShell Oil Company
InventorsLinda Rae Chamberlain, Carma J. Gibler
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Abstract
This is an improved process for the hydrogenation of conjugated diolefin polymers which comprises polymerizing or copolymerizing at least one conjugated diolefin with an organo alkali metal polymerization initiator in a suitable solvent thereby creating a living polymer, terminating the polymerization by the addition of hydrogen and effecting selective hydrogenation of the unsaturated double bonds in the conjugated diolefin units of the terminated polymer by contacting the polymer, in the absence of hydrocarbon lithium and alkoxy lithium compounds, with hydrogen in the presence of at least one bis(cyclopentadienyl)titanium compound. The improvement is the use of an alkyl benzoate as a promoter in the hydrogenation step.
Claims20
In a process for the hydrogenation of conjugated diolefin polymers which comprises:
- (a) polymerizing or copolymerizing at least one conjugated diolefin with an organo-alkali metal polymerization initiator in a suitable solvent thereby creating a living polymer,
- (b) terminating the polymerization by the addition of H.sub.2, and
- (c) selectively hydrogenating the unsaturated double bonds in the conjugated diolefin units of said terminated polymer by contacting the polymer, in the absence of hydrocarbon lithium and alkoxy lithium compounds, with hydrogen in the presence of at least one bis(cyclopentadienyl)titanium compound of the formula:
- ##STR3## wherein R.sub.1 and R.sub.2 are the same or different and are selected from the group consisting of halogen groups, C.sub.1 -C.sub.8 alkyl and alkoxy groups, C.sub.6 -C.sub.8 aryloxy groups, aralkyl, cycloalkyl groups, silyl groups and carbonyl groups, the improvement which comprises using an alkyl benzoate as a promoter in step (c) to enhance the hydrogenation of the polymer.
Dependencies are inferred from the claim text.