Polymerization of tetrahydrofuran
AssigneeBASF SE
InventorsHerbert Mueller, Otto H. Huchler, Herwig Hoffmann
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Abstract
A process for the preparation of polybutylene glycol carboxylic acid diesters of the formula R--CO--O--CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 --O).sub.n CO--R.sup.1 by polymerizing pretreated tetrahydrofuran in the presence of one or more carboxylic acids and/or carboxylic acid anhydrides and of a polymerization catalyst, especially antimony pentachloride or a bleaching earth containing less than 3% by weight of water, wherein the tetrahydrofuran is treated with a strong mineral acid, an organic sulfonic acid, silica gel and/or a bleaching earth prior to the polymerization.
Claims11
In a process for the preparation of polybutylene glycol carboxylic acid diesters of the formula
- R--CO--O--CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 --O).sub.n CO--R.sup.1
- where R and R.sup.1 are identical or different and each is alkyl, a carboxyl-containing aliphatic radical which may or may not be ethylenically unsaturated, or a carboxyl-containing aromatic radical and n is an integer from 2 to 200, by polymerizing tetrahydrofuran, wherein the tetrahydrofuran, after removal of the catalyst used in the preparation of the tetrahydrofuran, is treated, before polymerization, with a strong mineral acid, an organic sulfonic acid, silica gel and/or a bleaching earth, the treating agent is removed from the tetrahydrofuran, and the tetrahydrofuran is then polymerized in the presence of one or more carboxylic acid anhydrides and a polymerization catalyst, the improvement which comprises:
- using the polymerization catalyst a bleaching earth containing less than 3% by weight of water, said catalyst being arranged in a fixed bed, and passing a mixture of pretreated tetrahydrofuran and carboxylic anhydride through said fixed bed.
Dependencies are inferred from the claim text.