Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From heterocyclic reactant containing as ring atoms oxygen,...
Patent
1998-01-22
2000-03-28
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From heterocyclic reactant containing as ring atoms oxygen,...
512410, 512411, 512417, C08G 6112
Patent
active
060433388
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of copolymers of tetrahydrofuran (THF) and but-2-yne-1,4-diol by catalytic polymerization of THF. The present invention relates in particular to a process for the preparation of polyoxytetramethylene glycol. Polyoxytetramethylene glycol, also referred to as polytetrahydrofuran (PTHF), is produced worldwide and serves as an intermediate for the preparation of polyurethane, polyester and polyamide elastomers, for the preparation of which it is used as a diol component. The incorporation of PTHF into these polymers renders them soft and flexible, and PTHF is therefore also referred to as the soft segment component for these polymers.
The cationic polymerization of tetrahydrofuran (THF) with the aid of catalysts was described by Meerwein et al. (Angew. Chem. 72 (1960), 927). Either premolded catalysts are used here as catalysts, or the catalysts are produced in situ in the reaction mixture. This is done by producing oxonium ions in the reaction medium with the aid of strong Lewis acids, such as boron trifluoride, aluminum chloride, tin tetrachloride, antimony pentachloride, iron(III) chloride or phosphorus pentafluoride, or by means of strong Bronsted acids, such as perchloric acid, tetrafluoroboric acid, fluorosulfonic acid, chlorosulfonic acid, hexachlorostannic(IV) acid, iodic acid, hexachloroantimonic(V) acid or tetrachloroferric(III) acid, and with the aid of reactive compounds referred to as promoters, such as alkylene oxides, eg. ethylene oxide, propylene oxide, epichlorohydrin, ortho-acid esters, acetals, .alpha.-haloethers, acetyl chloride, carboxylic anhydrides, thionyl chloride or phosphoryl chloride, said oxonium ions initiating the polymerization of the THF. From the large number of these catalyst systems, however, only a few have become industrially important, since some of them are highly corrosive and/or lead to discolored PTHF products in the preparation of PTHF, which only have limited use. Furthermore, many of these catalyst systems do not have the catalytic action in the true sense but have to be used in stoichiometric amounts, based on the macromolecule to be prepared, and are consumed during the polymerization.
U.S. Pat. No. 3,358,042 describes the preparation of PTHF using fluorosulfonic acid as the catalyst. A particular disadvantage of the use of halogen-containing catalyst compounds is that they lead to the formation of halogenated byproducts during the PTHF preparation, which byproducts are very difficult to separate from the pure PTHF and have an adverse effect on its properties.
In the preparation of PTHF in the presence of the stated promoters, these promoters are incorporated into the PTHF molecule so that the primary product of the THF polymerization is not PTHF but a PTHF derivative. For example, alkylene oxides are incorporated as comonomers into the polymer, with the result that THF/alkylene oxide copolymers having properties, in particular performance characteristics, which differ from those of PTHF are formed.
The use of carboxylic anhydrides as promoters results primarily in the formation of PTHF diesters, from which PTHF must be liberated in a further reaction, for example by hydrolysis or transesterification (cf. U.S. Pat. No. 2 499 725 and DE-A 27 60 272).
According to U.S. Pat. No. 5,149,862, sulfate-doped zirconium dioxide is used as an acidic heterogeneous polymerization catalyst which is insoluble in the reaction medium. In order to accelerate the polymerization, a mixture of acetic acid and acetic anhydride is added to the reaction medium, since the polymerization takes place only very slowly in the absence of these promoters and, for example, a conversion of only 6% is achieved during a period of 19 hours. This process results in the formation of PTHF diacetates, which then have to be converted into PTHF by hydrolysis or transesterification.
JP-A 83 028/1983 describes the polymerization of THF in the presence of an acyl halide or carboxylic anhydride, a heteropolyacid being used as the catalyst. PTHF d
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Angew. Chem., vol. 72, 1960, pp. 927-934.
Becker Rainer
Eller Karsten
Fischer Rolf
Heilen Gerd
Plitzko Klaus-Dieter
Aylward D.
BASF - Aktiengesellschaft
Marquis Melvyn I.
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