Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymerizing in two or more physically distinct zones
Patent
1997-11-25
1999-10-05
Teskin, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymerizing in two or more physically distinct zones
526 73, 526237, 5263487, 585510, 585521, 585525, C08F11010, C08F 414
Patent
active
059626046
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of low molecular weight, highly reactive polyisobutene having an average molecular weight M.sub.n of from 500 to 20000 Dalton and containing over 80 mol % of terminal double bonds by the polymerization of isobutene or an isobutene-containing hydrocarbon stream in the liquid phase and with the aid of a boron trifluoride complex catalyst at from 0 to -40.degree. C. and from 1 to 20 bar.
Low molecular weight and high molecular weight polyisobutenes having molecular weights of up to several 100000 Dalton have long been known and their preparation is described, for example, in H. Guterbock: Polyisobutylen und Mischpolymerisate, pages 77 to 104, Springer, Berlin 1959. The currently available polyisobutenes of this molecular weight range are generally prepared with the aid of Lewis acid catalysts, such as aluminum chloride, alkylaluminum chlorides or boron trifluoride, and generally have less than 10 mol % of terminal double bonds (vinylidene groups) and a molecular weight distribution (dispersity) of from 2 to 7.
A distinction must be made between these conventional polyisobutenes and the highly reactive polyisobutenes, which as a rule have average molecular weights of from 500 to 5000 Dalton and preferably contain substantially more than 60 mol % of vinylidene groups. Such highly reactive polyisobutenes are used as intermediates for the preparation of additives for lubricants and fuels, as described, for example, in DE-A 27 02 604. For the preparation of these additives, polyisobutene/maleic anhydride adducts, in particular polyisobutenylsuccinic anhydrides, are first produced by reacting the terminal double bonds of the polyisobutene with maleic anhydride, and said adducts are then reacted with certain amines to give the finished additive. Since in adduct formation with maleic anhydride it is mainly the vinylidene double bonds which react, whereas, depending on their position in the macromolecule, the double bonds present further in the interior of the macromolecules lead to substantially lower, if any, conversion without the addition of halogens, the amount of terminal double bonds in the molecule is the most important quality criterion for this type of polyisobutene.
The formation of the vinylidene double bonds and the isomerization of the terminal double bonds in the isobutene macromolecules to internal double bonds are, according to Puskas et al., J. Polymer Sci.: Symposium No. 56 (1976), 191, based on the concepts shown in the scheme below: ##STR1##
The polyisobutene cation I formed in the course of the polymerization reaction may be converted into the relevant polyisobutene as a result of the elimination of a proton. The proton may be eliminated from one of the .beta.-methyl groups or from the internal .gamma.-methylene group. Depending on which of these two positions the proton is eliminated from, a polyisobutene having a vinylidene double bond II or having a trisubstituted double bond III present close to the end of the molecule is formed.
The polyisobutene cation I is relatively unstable and attempts to achieve stability by rearrangement to form more highly substituted cations. Both 1,3-methyl group shifts to give the polyisobutene cation IV and successive or concerted 1,2-hydride group and 2,3-methyl group shifts to give the polyisobutene cation V may take place. Depending on the position from which the proton is eliminated, in each case three different polyisobutene double bond isomers can form from the cations IV and V. However, it is also possible for the cations IV and V to undergo further rearrangement, causing the double bond to migrate further into the interior of the polyisobutene macromolecule.
All these deprotonations and rearrangements are equilibrium reactions and therefore reversible, but in the end the formation of more stable, more highly substituted cations and hence the formation of polyisobutenes having an internal double bond with establishment of the thermodynamic equilibrium are preferred. These deprotonations, proton
REFERENCES:
patent: 4152499 (1979-05-01), Boerzel et al.
patent: 4663406 (1987-05-01), Bronstert et al.
patent: 5408018 (1995-04-01), Rath
Polyisobutylen und Isobutylen-Mischpolymerisate, Gueterbock, Springer-Verlag 1959.
J. Polymer Sci. Symposium No. 56, 191 (1976).
BASF - Aktiengesellschaft
Teskin Fred
LandOfFree
Process for preparing low molecular weight, highly reactive poly does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for preparing low molecular weight, highly reactive poly, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing low molecular weight, highly reactive poly will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1172737