Process for the preparation of aliphatic polycarbonates and polyurethanes therefrom
AssigneeBayer Aktiengesellschaft
InventorsHans-Josef Buysch, Heinrich Krimm, Hans Rudolph
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Abstract
The present invention relates to a process for the preparation of polycarbonates which contain aliphatically bound hydroxyl groups by transesterification of aliphatic dihydroxy compounds with glycol carbonate, optionally in the presence of transesterification catalysts, with simultaneous separation of the glycol by fractional distillation, which process is characterized in that ethylene glycol is removed from the reaction mixture as an azeotropic mixture by means of inert solvents with which ethylene glycol is substantially immiscible. The present invention further relates to the preparation of polyurethanes from these polycarbonates.
Claims14
A transesterification process for the preparation of polycarbonates containing aliphatically bound hydroxyl end groups comprising:
- (a) reacting
- (i) aliphatic dihydroxyl compounds with
- (ii) glycol carbonate, in the presence of
- (iii) inert solvents selected from the group of compounds consisting of toluene, xylene, ethylbenzene, cumene, 1,2,4-trimethylbenzene, mesitylene, tetramethylbenzene, cymene, diethylbenzene, diisopropylbenzene, chlorotoluene, bromobenzene, tetralin, propenylbenzene, allylbenzene, .alpha.-methylstyrene, dibutylether, diisobutylether, diamylether, anisole, phenetole, cresol methyl ether, dibutyl ketone, di-tert.-butyl ketone and diamyl ketone, in which ethylene glycol is substantially immiscible, said inert solvents being capable of forming azeotropes with the ethylene glycol to permit selective azeotropic separation of said ethylene glycol;
- and
- (b) simultaneously separating the ethylene glycol by fractional distillation.
In a process for the preparation of polycarbonates containing aliphatically bound hydroxyl end groups comprising transesterification of aliphatic dihydroxyl compounds with glycol carbonate with simultaneous separation of ethylene glycol by fractional distillation, the improvement comprising removing ethylene glycol from the reaction mixture as an azeotropic mixture with inert solvents selected from the group of compounds consisting of toluene, xylene, ethylbenzene, cumene, 1,2,4-trimethylbenzene, mesitylene, tetramethylbenzene, cymene, diethylbenzene, diisopropylbenzene, chlorotoluene, bromobenzene, tetralin, propenylbenzene, allylbenzene, .alpha.-methylstyrene, dibutylether, diisobutylether, diamylether, anisole, phenetole, cresol methyl ether, dibutyl ketone, di-tert.-butyl ketone and diamyl ketone, in which ethylene glycol is substantially immiscible, said inert solvents being capable of forming azeotropes with ethylene glycol to permit selective azeotropic separation of said ethylene glycol.
A transesterification process for the preparation of polycarbonates containing aliphatically bound hydroxyl end groups comprising:
- (a) reacting
- (i) aliphatic dihydroxyl compounds with
- (ii) glycol carbonate, in the presence of
- (iii) inert solvents selected from the group of ketones consisting of dibutyl ketone, di-tert.-butyl ketone and diamyl ketone in which ethylene glycol is substantially immiscible, said inert solvents being capable of forming azeotropes with the ethylene glycol to permit selective azeotropic separation of said ethylene glycol;
- and
- (b) simultaneously separating the ethylene glycol by fractional distillation.
In a process for the preparation of polycarbonates containing aliphatically bound hydroxyl end groups comprising transesterification of aliphatic dihydroxyl compounds with glycol carbonate with simultaneous separation of ethylene glycol by fractional distillation, the improvement comprising removing ethylene glycol from the reaction mixture as an azeotropic mixture with inert solvents selected from the group of ketones consisting of dibutyl ketone, di-tert.-butyl ketone and diamyl ketone in which ethylene glycol is substantially immiscible, said inert solvents being capable of forming azeotropes with ethylene glycol to permit selective azeotropic separation of said ethylene glycol.
Dependencies are inferred from the claim text.