公开(公告)号：US5288881A

公开(公告)日：1994-02-22

申请号：US848188

申请日：1992-03-12

申请人： Neville E. Drysdale ,  Kang Lin ,  Thomas W. Stambaugh

发明人： Neville E. Drysdale ,  Kang Lin ,  Thomas W. Stambaugh

IPC分类号： C07D319/12

CPC分类号： C07D319/12

摘要： An improved process for converting oligomers of alphahydroxycarboxylic acids, such as glycolic and lactic acid, to dimeric cyclic esters, such as glycolide and lactide. The continuous process is conducted at reduced pressures and depolymerizing temperatures in a heated columnar depolymerization zone, coupled with an essentially unheated receiver for unconverted oligomer. By feeding the oligomer to the upper end of the column while coordinating the feed rate with the depolymerization temperature such that a fraction of the oligomer is converted to a vapor product stream containing the cyclic ester and another fraction of the oligomer exits the column at its lower end and passes to the receiver vessel, the dimeric cyclic ester is produced at high production rates and the oligomer is subjected to minimal thermal stress.

摘要翻译： 用于将α-羟基羧酸（例如乙醇酸和乳酸）的低聚物转化为二聚环酯如乙交酯和丙交酯的改进方法。 连续方法在加热的柱状解聚区中的减压和解聚温度下进行，与用于未转化的低聚物的基本上不加热的接收体偶联。 通过将低聚物进料到塔的上端，同时使进料速率与解聚温度协调，使得低聚物的一部分转化成含有环酯的蒸气产物流，另一部分低聚物在其下部离开塔 结束并传递到接收容器，二聚环酯以高生产率生产，并且低聚物经受最小的热应力。

公开(公告)号：US5236560A

公开(公告)日：1993-08-17

申请号：US813189

申请日：1992-03-13

申请人： Neville E. Drysdale ,  Thomas W. Stambaugh ,  James V. Tarbell

发明人： Neville E. Drysdale ,  Thomas W. Stambaugh ,  James V. Tarbell

IPC分类号： B01D3/14 ,  C07D319/12

CPC分类号： B01D3/146 ,  C07D319/12 ,  Y10S203/20 ,  Y10S203/22

摘要： A dimeric cyclic ester of an alpha-hydroxycarboxylic acid (lactide) is separated and recovered from a vapor product stream containing the cyclic ester, the corresponding lower-boiling hydroxycarboxylic acid (lactic), higher-boiling oligomeric hydroxycarboxylic acid and water without the use of solvents. More specifically, the vapor stream is condensed to obtain a condensate containing substantially all the cyclic ester, and the condensate is refined by distillation means alone to recover the cyclic ester substantially free of water, the alpha-hydroxycarboxylic acid and the higher-boiling oligomers.

摘要翻译： 从包含环酯，相应的低沸点羟基羧酸（乳酸），高沸点低聚羟基羧酸和水的蒸气产物流中分离并回收α-羟基羧酸（丙交酯）的二聚环酯，而不使用 溶剂。 更具体地说，蒸气流被冷凝以得到含有基本上全部环状酯的冷凝物，并且通过蒸馏装置单独精制冷凝物以回收基本上不含水，α-羟基羧酸和高沸点低聚物的环状酯。