3,6-二甲基-1,4-二恶烷-2,5-二酮

反应条件: temp:170.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Glycolide (0.13 moles) was mixed with ε-caprolactone (1.18) and a catalytic amount of stannous octoate (0.262 mole) and 1-decanol (3.275 mole). The system was heated to 170° C. and was stirred at this temperature for 30 minutes. The reaction was then cooled to 120° C. Glycolide (0.65 moles) and dl-lactide (0.52 moles) were added to the prepolymer. After melting the second charge, the system was heated to 170° C. and was stirred at this temperature for 6.5 hours. At the conclusion of the reaction, the unreacted monomer was removed by heating at 130° C. under reduced pressure for 1.5 hours. The resulting polymer was characterized by DSC (for Tm), solution viscosity (for molecular dimensions), IR and NMR (for chemical composition). The reaction was then cooled to 120° C the system was heated to 170° C. was stirred at this temperature for 6.5 hours At the conclusion of the reaction the unreacted monomer was removed by heating at 130° C. under reduced pressure for 1.5 hours

反应条件: temp:170.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Glycolide (0.13 moles) was mixed with ε-caprolactone (1.18) and a catalytic amount of stannous octoate (0.262 mole) and 1-decanol (3.275 mole). The system was heated to 170° C. and was stirred at this temperature for 30 minutes. The reaction was then cooled to 120° C. Glycolide (0.65 moles) and dl-lactide (0.52 moles) were added to the prepolymer. After melting the second charge, the system was heated to 170° C. and was stirred at this temperature for 6.5 hours. At the conclusion of the reaction, the unreacted monomer was removed by heating at 130° C. under reduced pressure for 1.5 hours. The resulting polymer was characterized by DSC (for Tm), solution viscosity (for molecular dimensions), IR and NMR (for chemical composition). The reaction was then cooled to 120° C the system was heated to 170° C. was stirred at this temperature for 6.5 hours At the conclusion of the reaction the unreacted monomer was removed by heating at 130° C. under reduced pressure for 1.5 hours

反应条件: temp:170.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Glycolide (0.13 moles) was mixed with ε-caprolactone (1.18) and a catalytic amount of stannous octoate (0.262 mole) and 1-decanol (3.275 mole). The system was heated to 170° C. and was stirred at this temperature for 30 minutes. The reaction was then cooled to 120° C. Glycolide (0.65 moles) and dl-lactide (0.52 moles) were added to the prepolymer. After melting the second charge, the system was heated to 170° C. and was stirred at this temperature for 6.5 hours. At the conclusion of the reaction, the unreacted monomer was removed by heating at 130° C. under reduced pressure for 1.5 hours. The resulting polymer was characterized by DSC (for Tm), solution viscosity (for molecular dimensions), IR and NMR (for chemical composition). The reaction was then cooled to 120° C the system was heated to 170° C. was stirred at this temperature for 6.5 hours At the conclusion of the reaction the unreacted monomer was removed by heating at 130° C. under reduced pressure for 1.5 hours

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: The procedure as described in Example 14 was substantially repeated except that the reaction flask was charged with 108.1 grams (0.75 moles) of DL-lactide and 28.5 grams (0.25 moles) of caprolactone. The same amount of dodecanol (5.6 mL, 0.025 moles) and Tin catalyst (0.10 mL) were used as were the reaction temperatures and times. A total of 85.3 grams of a thick viscous polymer were obtained with considerable polymer left in the reaction flask. This polymer was the most viscous of all the polymers prepared but still flowed as a liquid. The liquid polymer had a molecular weight as determined by GPC-MALS of 8086 daltons with a polydispersity of 1.21. the reaction temperatures and times

反应条件: temp:160.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Next, 72.3 grams (0.50 moles) of DL-lactide (Purac) was weighed and placed into the round-bottom flask. Then 57.1 grams (0.50 moles) of ε-caprolactone (Fluka) was weighed and placed in the flask. To this mixture was added 5.6 mL (0.025 moles) of dodecanol and 0.1 mL of the Tin catalyst. The round-bottom flask was placed in an oil bath and heated at 160° C. for 18 hours with stirring by a magnetic stirring bar. The flask was cooled to 110° C. and a vacuum was pulled for 12 hours to remove any residual monomer. The flask was then cooled to room temperature, the vacuum released, and the thick viscous liquid polymer transferred to a sealed glass container. A total of 96.7 grams of the viscous liquid polymer was obtained. The molecular weight (MW) of the copolymer as determined by gel permeation chromatography with a multi-angle light-scattering detector (GPC-MALS) was 8250 daltons with a polydispersity (MW/MN) of 1.13. The round-bottom flask was placed in an oil bath The flask was cooled to 110° C. to remove any residual monomer The flask was then cooled to room temperature

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 100 g of the thus obtained residue is heated with 50 g hydrolysis medium (90% lactic acid in aqueous solution) at 100° C. and atmospheric pressure for 4 hours with reflux and continuous thorough mixing. The resulting solution is mixed with sodium sulphide and, after 30 min thorough mixing, is filtered in order to remove solid material particles. The thus obtained, homogeneous solution has a lactic acid proportion of over 99% by weight and a racemisation degree of 2.5% and can be mixed with polycondensate in order to supply it directly to the depolymerisation unit. The total racemisation degree of the dilactide obtained after a plurality of cycles never rises, despite the recycling, above the maximum value which is achieved during direct depolymerisation up to a conversion of 95% (see example 1). The total yield is determined by the quantity which is removed during the hydrolysis by separation of the impurities and is preferably above 99%, however in any case more than 95%. atmospheric pressure for 4 hours with reflux is filtered in order to remove solid material particles The thus obtained a racemisation degree of 2.5% and can be mixed with polycondensate in order to supply it directly to the depolymerisation unit

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: When DL-lactic acid is used as a raw material, the crude lactide has a high meso-lactide content. When the crude lactide is gradually cooled, DL-lactide is precipitated and allowed to persist in the form of crystals in the molten meso-lactide phase and the whole crude lactide assumes a slurry state. The crude lactide in the slurry state is mixed with a substantially equal weight of water and the resultant mixture is immediately cooled to the vicinity of 30° C. for the purpose of preventing DL-lactide from undergoing hydrolysis and kept stirred at this temperature for a period in the range of 30 minutes to one hour, with the result that meso-lactide is dissolved in water and, at the same time, part of the dissolved meso-lactide undergoes hydrolysis. The crystals of DL-lactide are separated by filtration from the water phase and are dissolved in such an organic solvent as acetone or MIBK thereby recrystallizing therefrom to produce easily DL-lactide crystals of high purity. hydrolysis The crystals of DL-lactide are separated by filtration from the water phase are dissolved in such an organic solvent as acetone or MIBK thereby recrystallizing

反应条件: temp:170.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Glycolide (0.13 moles) was mixed with ε-caprolactone (1.18) and a catalytic amount of stannous octoate (0.262 mole) and 1-decanol (3.275 mole). The system was heated to 170° C. and was stirred at this temperature for 30 minutes. The reaction was then cooled to 120° C. Glycolide (0.65 moles) and dl-lactide (0.52 moles) were added to the prepolymer. After melting the second charge, the system was heated to 170° C. and was stirred at this temperature for 6.5 hours. At the conclusion of the reaction, the unreacted monomer was removed by heating at 130° C. under reduced pressure for 1.5 hours. The resulting polymer was characterized by DSC (for Tm), solution viscosity (for molecular dimensions), IR and NMR (for chemical composition). The reaction was then cooled to 120° C the system was heated to 170° C. was stirred at this temperature for 6.5 hours At the conclusion of the reaction the unreacted monomer was removed by heating at 130° C. under reduced pressure for 1.5 hours