Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By addition of entire unsaturated molecules – e.g.,...
Patent
1998-01-27
1999-08-31
Caldarola, Glenn A.
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By addition of entire unsaturated molecules, e.g.,...
585520, 585526, 585527, 585530, 5263487, 526107, C07C 202, C08F 1000, C08F 418
Patent
active
059455756
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of halogen-free, reactive polyisobutene having a content of terminal double bonds of more than 50 mol % and an average molecular weight M.sub.n of from 500 to 5000 dalton by the cationic polymerization of isobutene or isobutene-containing hydrocarbon mixtures in the liquid phase.
In the polymerization of isobutene a non-separable mixture of polyisobutenes having varying positioning of the double bond in the individual polyisobutenes is formed. Polyisobutenes of formula I ##STR1## in which n indicates the degree of polymerization, which in turn ensues from the average molecular weight M.sub.n of the polyisobutene prepared, contain terminal vinylidene-type C--C double bonds, which are also designated as .alpha.-olefinic double bonds in this application due to their position in the polyisobutene molecule. Accordingly the double bonds in polyisobutenes of formula II ##STR2## are designated as being .beta.-olefinic. If no particular measures are taken in the polymerization of isobutene, there is formed a statistical mixture of polyisobutenes containing .alpha.-olefinic, ie terminal, .beta.-olefinic double bonds and also some located more in the interior of the polyisobutene molecule. The content of terminal double bonds in a polyisobutene product prepared according to a specified manufacturing method as also the content of .beta.-olefinic double bonds is given in mol %.
Polyisobutenes having molecular weights of up to 100,000 dalton are known. The preparation of these olefins, which is described, for example, in H. Guterbock, Polyisobutylene und Mischpolymerisate, pp 77-104, Springer Verlag, Berlin, 1959, is usually effected by Lewis acid-catalyzed isobutene polymerization, the Lewis acids used being aluminum chloride, alkylaluminum chloride, or boron trifluoride. However, the polymers thus obtained have a relatively small content of terminal vinylidene-type C--C double bonds of less than 10 mol %.
On the other hand, reactive polyisobutene (PIB) having molecular weights usually ranging from 500 to 5000 dalton possesses a high content of terminal vinylidene groups, preferably more than 50 mol %. These reactive polyisobutenes are used as intermediates for the preparation of additives for lubricants and fuels, as described, for example, in DE-A 2,702,604. In order to prepare these additives polyisobutene is first of all caused to react with maleic anhydride. In this operation the terminal vinylidene-type double bonds preferentially react, whereas double bonds situated more in the interior of the macromolecule, react to a lesser extent or not at all depending on their position in the molecule. The polyisobutene/maleic anhydride adducts formed are subsequently converted to the corresponding additives by reaction with specific amines. A high content of terminal double bonds is therefore absolutely necessary for polyisobutenes used as starting materials for said additives. The same applies to the preparation of polyisobutene amines likewise used as fuel additives according to EP-A 244,616, which are produced by hydroformylation of the reactive polyisobutene and subsequent reductive amination of the polyisobutene aldehyde thus obtained. Here polyisobutene having a high content of terminal double bonds is again preferably used, but .beta.-olefinic polyisobutenes are also hydroformylated to form the desired product in hydroformylation using cobalt catalysts, on account of their double bond isomerization activity.
The preparation of reactive polyisobutene by the polymerization, effected by homogeneous catalysis, of isobutene is already known. For example, according to DE-A, 2,702,604 there is obtained, by reaction of isobutene in the presence of boron trifluoride, a polyisobutene product having a content of terminal double bonds of up to 88%. EP-A 145,235 teaches the polymerization of isobutene in the presence of a complex of boron trifluoride and a primary alcohol at temperatures ranging from -100.degree. to +50.degree. C., where products having similarly hig
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Fischer Rolf
Gehrer Eugen
Muller Ulrich
Rath Hans Peter
Sigwart Christoph
Bullock In Suk
Caldarola Glenn A.
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