Method for purifying glycolide

Abstract

The invention relates to a method for purifying glycolide. The method comprises the following steps of: mixing coarse glycolide with an alkaline reagent at an ordinary pressure; heating to melt down the coarse glycolide and enabling the melt coarse glycolide to react with the alkaline reagent; and then rising the temperature of the system continuously and depressurizing to distill the glycolide so as to obtain refined glycolide. As no organic solvent is used, the method for purifying the glycolide has very low pollution, low cost, short purification period, and convenience in operation, and can ensure the refined glycolide to have the yield rate of more than 80% and the purity of more than 99.5%.

Description

technical field

[0001] The invention relates to a method for purifying glycolide. Background technique

[0002] Polyglycolide and its copolymers have good biocompatibility and biodegradability. The degradation products are non-toxic to the human body and can be absorbed and metabolized by human tissues. As an important class of biomedical polymer materials, they have attracted widespread attention. Surgical sutures, bone fixation and repair, drug controlled release, artificial blood vessels, tissue engineering and other fields have been applied.

[0003] High-molecular-weight polyglycolide usually needs to be obtained by ring-opening polymerization of high-purity glycolide, and glycolide is synthesized by high-temperature cracking of glycolic acid oligomers in the presence of a catalyst. Glycolide synthesized by this method Contains impurities such as water, glycolic acid, and glycolic acid oligomers. Glycolide containing these impurities is called "crude glycolide". These ...

Examples

Embodiment 1

[0031] Synthesis of crude glycolide: Add 3000 g of 70% glycolic acid aqueous solution and 8.0 g of catalyst Sb to a 5 L flask 2 o 3 , stirred under normal pressure, heated the solution to 190°C for dehydration, then lowered the system pressure to 8.0kPa for further dehydration for 1.5 hours to obtain glycolic acid oligomers, then raised the temperature to 230-270°C, and reduced the pressure to 1.0kPa. The glycolic acid oligomer was cracked to obtain 1150 grams of crude glycolide.

Embodiment 2

[0033] Purification of crude glycolide: use the crude glycolide synthesized in Example 1, put 100 grams of crude glycolide into a 250 mL flask under normal pressure, add 6.0 grams of Na, heat to 80 ° C to melt the crude glycolide , reacted at this temperature for 1 hour, then continued to heat up to 140 ° C, lowered the system pressure to 100 Pa, and distilled for 2 hours to obtain 82 g of refined glycolide with a yield of 82%. The melting point (as determined by DSC) of refined glycolide is 82.6°C and the purity is 99.8%.

Embodiment 3

[0035] With the crude glycolide synthesized in Example 1. Under normal pressure, take 120 grams of crude glycolide and put it into a 250mL flask, add 9.0 grams of CaH 2 , heated to 85°C to melt the crude glycolide, reacted at this temperature for 1.5 hours, then continued to heat up to 150°C, lowered the system pressure to 200Pa, and distilled for 2.5 hours to obtain 100 grams of refined glycolide with a yield of 83 %. The melting point (as determined by DSC) of refined glycolide is 82.5°C and the purity is 99.7%.

technical field

[0001] The invention relates to a method for purifying glycolide. Background technique

[0002] Polyglycolide and its copolymers have good biocompatibility and biodegradability. The degradation products are non-toxic to the human body and can be absorbed and metabolized by human tissues. As an important class of biomedical polymer materials, they have attracted widespread attention. Surgical sutures, bone fixation and repair, drug controlled release, artificial blood vessels, tissue engineering and other fields have been applied.

[0003] High-molecular-weight polyglycolide usually needs to be obtained by ring-opening polymerization of high-purity glycolide, and glycolide is synthesized by high-temperature cracking of glycolic acid oligomers in the presence of a catalyst. Glycolide synthesized by this method Contains impurities such as water, glycolic acid, and glycolic acid oligomers. Glycolide containing these impurities is called "crude glycolide". These ...

Examples

Embodiment 1

[0031] Synthesis of crude glycolide: Add 3000 g of 70% glycolic acid aqueous solution and 8.0 g of catalyst Sb to a 5 L flask 2 o 3 , stirred under normal pressure, heated the solution to 190°C for dehydration, then lowered the system pressure to 8.0kPa for further dehydration for 1.5 hours to obtain glycolic acid oligomers, then raised the temperature to 230-270°C, and reduced the pressure to 1.0kPa. The glycolic acid oligomer was cracked to obtain 1150 grams of crude glycolide.

Embodiment 2

[0033] Purification of crude glycolide: use the crude glycolide synthesized in Example 1, put 100 grams of crude glycolide into a 250 mL flask under normal pressure, add 6.0 grams of Na, heat to 80 ° C to melt the crude glycolide , reacted at this temperature for 1 hour, then continued to heat up to 140 ° C, lowered the system pressure to 100 Pa, and distilled for 2 hours to obtain 82 g of refined glycolide with a yield of 82%. The melting point (as determined by DSC) of refined glycolide is 82.6°C and the purity is 99.8%.

Embodiment 3

[0035] With the crude glycolide synthesized in Example 1. Under normal pressure, take 120 grams of crude glycolide and put it into a 250mL flask, add 9.0 grams of CaH 2 , heated to 85°C to melt the crude glycolide, reacted at this temperature for 1.5 hours, then continued to heat up to 150°C, lowered the system pressure to 200Pa, and distilled for 2.5 hours to obtain 100 grams of refined glycolide with a yield of 83 %. The melting point (as determined by DSC) of refined glycolide is 82.5°C and the purity is 99.7%.