Method for synthesizing glycolide

A technology of glycolide and methyl glycolate, which is applied in the field of polymer monomer preparation, can solve problems such as coking, complex catalyst preparation process, and low yield of glycolide

Active Publication Date: 2021-09-14
EAST CHINA UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The gas-phase direct cyclization catalyst preparation process is complicated, easy to deactivate quickly, low processing capacity, high energy consumption, and has no industrialization prospects
[0010] Generally speaking, in the current synthesis route of glycolide, the process route of depolymerization of oligomers has a high viscosity due to the high viscosity of glycolic acid oligomers formed by oligomerization, and the heat transfer effect is very poor in the process of depolymerization at elevated temperature, which will cause Causes severe coking and heaviness, resulting in low yield of glycolide and residues left in the reactor that are difficult to clean
The introduction of solvent copolymerization and other methods can reduce coking, but the separation and purification of solvents are often required, and the cost is high
However, the process route of direct synthesis of glycolide in the gas phase is still in the initial stage of research, and currently only stays in the laboratory stage, and the catalyst preparation process used is complicated, the processing capacity is low, and problems such as coking and deactivation are prone to occur

Method used

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  • Method for synthesizing glycolide
  • Method for synthesizing glycolide
  • Method for synthesizing glycolide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] The synthetic method of the glycolide of the present embodiment comprises the following two steps:

[0043] Step 1: Weigh 16.30g of n-docosanol into a 100mL flask, melt at 60°C, add 4.50g of methyl glycolate and 0.018g of stannous octoate, stir magnetically, and slowly raise the temperature to 140°C until no distillation The effluent was evaporated, and the light yellow liquid in the flask was behenyl glycolate.

[0044] Step 2: Heat the esterification product obtained in Step 1 to 225°C, and vacuumize the system to reduce the pressure to 0.5kPa. At this time, a colorless distillate can be collected, which will condense into white crystals when it is cooled. Wait until there is no liquid distillate out, the reaction was terminated. The distillate is glycolide, weighing 2.07g, and the yield of crude glycolide is calculated to be 71.40%.

[0045] figure 2 It is the proton nuclear magnetic spectrum of the glycolide prepared by the present embodiment.

[0046] From f...

Embodiment 2

[0061] The synthetic method of the glycolide of the present embodiment comprises the following two steps:

[0062] Step 1: Weigh 14.90g of eicosanol into a 100mL flask, melt at 80°C, add 4.50g of methyl glycolate and 0.018g of stannous octoate, stir magnetically, and slowly heat up to 140°C until there is no distillate After steaming, the light yellow liquid in the flask is eicosyl glycolate.

[0063] Step 2: Heat the esterification product obtained in Step 1 to 210°C, and vacuumize the system to reduce the pressure to 1kPa. At this time, a colorless distillate can be collected, which will condense into white crystals when it is cooled, and wait for no liquid to distill out. , the reaction was terminated. The distillate is glycolide, weighing 1.92g, and the yield of crude glycolide is 66.20%.

Embodiment 3

[0065] The synthetic method of the glycolide of the present embodiment comprises the following two steps:

[0066] Step 1: Weigh 16.30g of n-docosanol into a 100mL flask, melt at 80°C, add 4.50g of methyl glycolate and 0.0675g of stannous chloride, stir magnetically, and slowly raise the temperature to 160°C until no The distillate was evaporated, and the light yellow liquid in the flask was behenyl glycolate.

[0067] Step 2: Raise the temperature of the esterified product obtained in Step 1 to 220°C, and reduce the pressure of the system to 1.5kPa by vacuuming. At this time, a colorless distillate can be collected, which will condense into white crystals when it is cooled. Wait until there is no liquid distillate out, the reaction was terminated. The distillate was glycolide, weighing 2.04g, and the crude yield of glycolide was 70.20%.

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Abstract

The invention discloses a method for synthesizing glycolide, wherein methyl glycolate is used as a raw material, and the glycolide is obtained through the following two steps: (1) a reaction defined in the specification, and (2)a reaction defined in the specification, wherein ROH is 18-30 carbon straight chain or branched chain alcohol, acid or ester containing one or more hydroxyl groups. According to the glycolide synthesis process, high-boiling-point alcohol is introduced to participate in the reaction to generate a glycolic acid higher ester intermediate product, and the molecular weight of the glycolic acid higher ester intermediate product is far lower than that of an intermediate product glycolic acid oligomer in a traditional process, so that the viscosity of a reaction system is controlled to be at a low level, the heat transfer efficiency of the system is improved, and the problem that the traditional oligomerization route is easy to coke and carbonize is effectively avoided.

Description

technical field [0001] The invention relates to the technical field of polymer monomer preparation, in particular to a method for synthesizing glycolide. Background technique [0002] With the increasing white pollution, the demand for degradable plastics in various countries is growing rapidly. As a biodegradable plastic with excellent performance, polyglycolic acid (PGA) has great market potential in medical materials and packaging materials. [0003] There are two main synthetic routes for PGA: (1) direct dehydration polymerization of glycolic acid; and (2) ring-opening polymerization of glycolide. Although the direct dehydration polymerization process of glycolic acid has a simple route, it cannot obtain a sufficiently high molecular weight, which greatly limits the scope of application of this route to synthesize PGA. Although the process route of glycolide ring-opening polymerization is more complicated, it can meet different application requirements by controlling t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12
CPCC07D319/12Y02P20/584
Inventor 周静红徐晓峰曹约强李伟周兴贵
Owner EAST CHINA UNIV OF SCI & TECH
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