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One pot recovery of D,L-lactide from D.L-lactide recrystallization residual liquid

A technology of lactide and recrystallization, applied in the field of biomedical material recycling, can solve the problems of pollution, waste of resources, environment, and difficult utilization of residues.

Inactive Publication Date: 2004-11-17
WUHAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If it is discarded, it will not only cause resource waste and environmental pollution, but also lose production efficiency and economic benefits
Studies have shown that it is difficult to obtain lactide crystallization in the remaining residue with the usual volatilization-crystallization or evaporation-crystallization method, and what is obtained is dark brown or black viscous or jelly, which makes the residue become more difficult to use

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Embodiment 1. directly add 1800 parts (by mass, the same below) D, the commercially available ZnO of L-lactide recrystallization raffinate and catalytic amount in the reactor with thermometer in 3000mL, receive water condensation atmospheric pressure distillation Apparatus, heating, distilling out most of ethyl acetate, ethanol, acetic acid, water and other impurities contained in the raffinate under normal pressure until the temperature of the distillate rises to 140°C, at this time the distillate starts to appear light yellow. Replace the receiving container, use an air condenser, connect to a vacuum system, heat to control the reaction temperature to always be lower than 255°C, start distillation under reduced pressure (-0.099MPa), collect the distillate at 160°C-180°C, and obtain crude D, L- 172.8 parts of lactide, yield 9.6%. The crude product was recrystallized three times with ethyl acetate and dried in vacuum for 24 hours to obtain pure D,L-lactide with a meltin...

Embodiment 2

[0013] Example 2. Into a 3000mL reactor with a thermometer, directly add 1800 parts of D, the commercially available ZnO of L-lactide recrystallization raffinate and a catalytic amount, connect water to condense an atmospheric distillation device, heat, under normal pressure Evaporate most of the ethyl acetate, ethanol, acetic acid, water and other impurities contained in the raffinate until the temperature of the distillate rises to 140°C, at which time the distillate starts to turn light yellow. Replace the receiving container, use an air condenser, connect to a vacuum system, heat to control the reaction temperature to always be lower than 255°C, start distillation under reduced pressure (-0.099MPa), collect the distillate at 160°C-190°C, and obtain crude D, L- 192.6 parts of lactide, yield 10.7%. The crude product was recrystallized three times with ethyl acetate and dried in vacuum for 24 hours to obtain pure D,L-lactide with a melting point of 126.5°C.

Embodiment 3

[0014] Embodiment 3. In 3000mL reactor with thermometer, directly add 1500 parts of D, the commercially available ZnO of L-lactide recrystallization raffinate and catalytic amount, receive water condensation atmospheric distillation device, heat, under normal pressure Evaporate most of the ethyl acetate, ethanol, acetic acid, water and other impurities contained in the raffinate until the temperature of the distillate rises to 140°C, at which time the distillate starts to turn light yellow. Replace the receiving container, use an air condenser, connect to a vacuum system, heat to control the reaction temperature to always be lower than 255°C, start distillation under reduced pressure (-0.099MPa), collect the distillate at 160°C-190°C, and obtain crude D, L- 159.0 parts of lactide, yield 10.6%. The crude product was recrystallized four times with ethyl acetate and dried in vacuum for 24 hours to obtain pure D,L-lactide with a melting point of 127.0°C.

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Abstract

A process for recovering D,L-lactide from the residual liquid after recrystallization of D,L-lactide by reactor method using ZnO as catalyst includes ordinary-pressure distilling to remove ethyl acetate, alcohol, acetic acid and water until temp reaches 140 deg.C, changing collecting container and connecting vacuumizing system, heating to temp lower than 255 deg.C, distilling under 0-0.099 MPa, collecting the fraction liquid at 160-195 deg.C, cooling to educe out raw D,L-lactide crystal, recrystallizing in ethyl acetate 3-5 times, and vacuum drying for 24-48 hr. Its advantages are high purity and no environmental pollution.

Description

technical field [0001] The invention relates to biomedical material recovery technology, in particular to a method for recovering D, L-lactide from D, L-lactide recrystallization raffinate by a mid-kettle method. Background technique [0002] Lactide is an important intermediate for the production of polylactic acid, usually D, L-lactide, L-lactide, D-lactide. Polylactic acid with different molecular weight and configuration can be obtained by ring-opening polymerization of different lactides in the presence of catalysts. It is known that various polylactic acids can be used to prepare tissue engineering scaffolds, drug release carriers, surgical sutures, fracture internal fixation materials, and agricultural film materials. In order to obtain high molecular weight or ultra-high molecular weight polylactic acid (M v ≥1.0×10 6 ), one of the approaches is first to prepare high-purity lactide. It can be achieved by repeated recrystallization of crude lactide of the correspo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D319/12
Inventor 张胜民李世普毛茫茫阎玉华
Owner WUHAN UNIV OF TECH