- Process for the preparation of cyclic esters and method for purification of the same
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The present invention provides a process for production of a cyclic ester by depolymerization of an aliphatic polyester. In the process, a mixture containing the aliphatic polyester and a specific polyalkylene glycol ether, which has a boiling point of 230-450° C. and a molecular weight of 150-450, is heated under normal or reduced pressure to a temperature at which depolymerization of the aliphatic polyester takes place. Then, a substantially homogeneous solution phase, consisting of the melt phase of the aliphatic polyester and the liquid phase of the polyalkylene glycol ether, is formed. Heating of the solution phase is continued to form the cyclic ester by depolymerization and distil out the cyclic ester together with the polyalkylene glycol ether, and then the cyclic ester is recovered from the distillate. The present invention also provides a process for purification of a crude cyclic ester by use of the specific polyalkylene glycol ether described above.
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Page/Page column 11
(2010/11/30)
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- Preparation of etherified polyoxyalkylene derivatives
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Polyoxyalkylene compounds having at least four oxyalkylene units and one or two terminal hydroxyl groups are etherified by reacting same with organic primary chlorides or bromides in the presence of an aqueous, at least 30% by weight solution of sodium or potassium hydroxide to produce the corresponding etherified polyoxyalkylene derivatives. The molar ratio of the organohalide to the hydroxyl group(s) of the polyoxyalkylene compound is at least 1.2, and the molar ratio of the alkali metal hydroxide to such hydroxyl group(s) is at least 1.
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- Phase-Transfer Synthesis of Monoalkyl Ethers of Oligoethylene Glycols
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The effects of catalyst, temperature, solvent, and reagent ratios on the phase-transfer-catalyzed Williamson ether synthesis of monoalkyl ethers of oligoethylene glycols have been studied.A convenient method has been developed which gives reproducibly high yields of pure monoethers in the presence of aqueous sodium hydroxide.
- Gibson, Thomas
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p. 1095 - 1098
(2007/10/02)
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