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Method for preparing lactide continuously

A technology of lactide and esterification catalyst, applied in the direction of organic chemistry, can solve the problems of no description, defects, investment and production costs, etc., and achieve the effect of high industrial value

Active Publication Date: 2012-11-07
安徽京安润生物科技有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] Although these two methods seem to be advantageous, there are still a large number of disadvantages, and it is impossible to obtain economical and high-quality products in industrialization.
[0013] The second method introduces solution crystallization to obtain lactide of optical and chemical quality, however, this method consists of a large number of different processes, which increases the complexity of control and leads to higher investment and production costs
In addition, the method does not describe whether it is continuous production of lactide

Method used

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  • Method for preparing lactide continuously
  • Method for preparing lactide continuously
  • Method for preparing lactide continuously

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0072] Step 1: In a 1000ml reactor A equipped with an electric stirring system, a condensation system, a constant temperature heating system, and a vacuum system. According to 600ml / min, continuously add lactic acid with a weight content of 90% (the weight content of L-isomer accounts for 97.6%), adjust the heating resistor to control the heating temperature at 100°C, and vacuumize to 400kpa. In order to prevent too much lactic acid from being carried over in the effluent, a reactor with a height of 900mm and a cross-sectional area of ​​0.36m is placed on the top of the reactor. 2 The packed ring condensation column. There is a temperature indicator on the top of the column to monitor the temperature change, and at the same time reduce the heating power as much as possible to prevent more lactic acid from being taken away. Keep this state for 1.5 hours. Through the communication with the reactor B, adjust the valve to automatically enter the reactor B through the liquid phase...

Embodiment 2

[0081] Step 1: In a 1000ml reactor A equipped with an electric stirring system, a condensation system, a constant temperature heating system, and a vacuum system. According to 600ml / min, continuously add lactic acid with a weight content of 90% (the weight content of L-isomer is 97.6%), adjust the heating resistance to control the heating temperature at 95°C, and vacuumize to 200Kpa. In order to prevent too much lactic acid from being carried over in the effluent, a reactor with a height of 900mm and a cross-sectional area of ​​0.36m is placed on the top of the reactor. 2 The packed ring condensation column. There is a temperature indicator on the top of the column to monitor the temperature change, and at the same time reduce the heating power as much as possible to prevent more lactic acid from being taken away. Keep this state for 1.5 hours. Through the communication with the reactor B, adjust the valve to automatically enter the reactor B through the liquid phase material...

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Abstract

The invention provides a method for preparing lactide continuously and particularly relates to the method for preparing the lactide continuously under the low temperature condition. Reaction mass is added continuously to enable lactic acid to be reacted continuously so as to generate low polymer and be depolymerized into cyclic dimmer. An advanced distillation and fusion crystallization coupled purification process is adopted, purity and yield of products are improved, and production cost is reduced.

Description

technical field [0001] The invention relates to a method for preparing lactide, in particular to a method for continuously preparing lactide under low temperature conditions. Background technique [0002] The "continuous" method for producing lactide (US6277951B1, US6326458B1) described in the published literature in the world is still a batch production method in essence; that is to say, in the above-mentioned reaction, step A and step B are mutually independent , step A only provides raw materials for step B, and step A or step B itself is also a batch reaction process, which cannot realize the continuous progress of the two reactions and the continuous flow of materials between the two processes. There are serious problems in this traditional batch reaction method, that is, in the process of preparing lactide by cracking, it is easy to cause slow heat transfer of the material due to the continuous increase of the viscosity of the reactant, the system is heated unevenly, a...

Claims

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Application Information

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IPC IPC(8): C07D319/12
Inventor 史佳林
Owner 安徽京安润生物科技有限责任公司
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