DE1083275B - Process for the production of lactide - Google Patents
Process for the production of lactideInfo
- Publication number
- DE1083275B DE1083275B DED30990A DED0030990A DE1083275B DE 1083275 B DE1083275 B DE 1083275B DE D30990 A DED30990 A DE D30990A DE D0030990 A DED0030990 A DE D0030990A DE 1083275 B DE1083275 B DE 1083275B
- Authority
- DE
- Germany
- Prior art keywords
- lactide
- depolymerization
- polylactic acid
- production
- metals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D319/00—Heterocyclic compounds containing six-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D319/10—1,4-Dioxanes; Hydrogenated 1,4-dioxanes
- C07D319/12—1,4-Dioxanes; Hydrogenated 1,4-dioxanes not condensed with other rings
Description
Verfahren zur Herstellung von Lactid Milchsäure hat eine große Neigung zur Selbstveresterung und kann durch Erwärmen bei Normaldruck bzw. unter vermindertem Druck und Entfernen des bereits vorhandenen und des sich bildenden Wassers in Polymilchsäure übergeführt werden.Process for the production of lactide Lactic acid has a great propensity for self-esterification and can by heating at normal pressure or under reduced Pressure and removal of the water already present and the water that forms in polylactic acid be transferred.
Dieses Produkt ist in der Hauptsache ein linearer Polyester mit relativ niedrigem Molekulargewicht, der nur sehr geringe Mengen cyclischer Verbindungen enthält. Es ist bekannt, daß durch Erhitzen von Polymilchsäure Lactid gebildet wird. Weiter ist bekannt, daß die Lactidbildung aus Polymilchsäure durch Zusätze von Zink-oder Aluminiumverbindungen bzw. der betreffenden Metalle selbst begünstigt wird. Die bisher beschriebenen Verfahren beziehen sich auf die Herstellung von Lactid mit einem hohen Schmelzpunkt (124 bis 128°C), also von Produkten ohne bzw. mit nur geringer optischer Aktivität, aus in der Hauptsache inaktiver Milchsäure. Lactid kann wiederum zur Herstellung von hochmolekularer Polymilchsäure verwendet werden. Neuere Erkenntnisse zeigen, daß bei Verwendung von optisch aktivem Lactid mit niedrigem Schmelzpunkt (95 bis 98°C) Kunststoffe mit verbesserten physikalischen und chemischen Eigenschaften erhalten werden können.This product is mainly a linear polyester with relative low molecular weight, containing only very small amounts of cyclic compounds contains. It is known that lactide is formed by heating polylactic acid. It is also known that the lactide formation from polylactic acid by the addition of zinc or Aluminum compounds or the metals concerned themselves is favored. the Processes described so far relate to the production of lactide with a high melting point (124 to 128 ° C), i.e. products with no or only a low one optical activity, from mainly inactive lactic acid. Lactide can turn be used for the production of high molecular weight polylactic acid. Recent findings show that when using optically active lactide with a low melting point (95 to 98 ° C) plastics with improved physical and chemical properties can be obtained.
Die oben aufgeführten Katalysatoren, Metallverbindungen bzw. Metalle der IL und III. Gruppe des Periodischen Systems sind zur Herstellung von optisch aktivem Lactid aus optisch aktiver Milchsäure bzw. optisch aktiver Polymilchsäure wenig geeignet, weil sie bei der für die Depolymerisation von Polymilchsäure zu Lactid erforderlichen Temperatur eine beachtliche Verringerung der optischen Aktivität durch Teilracemisierung hervorrufen.The catalysts, metal compounds or metals listed above the IL and III. Group of the periodic table are used to make optical active lactide from optically active lactic acid or optically active polylactic acid little suitable because they are used in the depolymerization of polylactic acid too Lactide required a considerable reduction in optical activity caused by partial racemization.
Es wurde nun gefunden, daß die Herstellung von optisch aktivem Lactid und auch von inaktivem Lactid aus durch Entwässerung der entsprechenden Milchsäuren erhaltenen aktiven bzw. inaktiven Polymilchsäuren und auch aus durch Polymerisation der entsprechenden Lactide erhaltenen hochpolymeren Polymilchsäuren mit guter Ausbeute durchgeführt werden kann, wenn die Depolymerisation dieser Substanzen bei einer Badtemperatur von 190 bis 260°C, vorzugsweise bei 220 bis 250°C, unter Vakuum und in Gegenwart von Metallen der IV., V. oder VIII. Gruppe des Periodischen Systems oder von Verbindungen dieser Metalle durchgeführt wird.It has now been found that the production of optically active lactide and also from inactive lactide by dehydrating the corresponding lactic acids obtained active or inactive polylactic acids and also from by polymerization high polymeric polylactic acids obtained from the corresponding lactides in good yield can be carried out if the depolymerization of these substances at a Bath temperature of 190 to 260 ° C, preferably 220 to 250 ° C, under vacuum and in the presence of metals of group IV, V or VIII of the Periodic Table or of compounds of these metals.
Für die katalytische Depolymerisation geeignete Verbindungen sind z. B. die Oxyde, Hydroxyde und Salze von organischen und auch anorganischen Säuren, deren Dissoziationskonstante nicht größer als die von Milchsäure bzw. Polymilchsäure ist oder die bei höheren Temperaturen flüchtig sind oder eine Zersetzung erleiden. Man verwendet die Katalysatoren bevorzugt in Mengen von 0,05 bis 2 %, berechnet auf die Polymilchsäure.Compounds suitable for catalytic depolymerization are z. B. the oxides, hydroxides and salts of organic and inorganic acids, their dissociation constant is not greater than that of lactic acid or polylactic acid or which are volatile or decompose at higher temperatures. The catalysts are preferably used in amounts of 0.05 to 2%, calculated on the polylactic acid.
Es wurde weiter gefunden, daß mit Hilfe dieser Katalysatoren die Depolymerisation besonders leicht erfolgt, daß die Depolymerisationsprodukte mit größerer Reinheit anfallen und daß sich nur wenig Rückstand bildet. Die Depolymerisation kann bei laufender Zugabe von Polymilchsäure auch kontinuierlich durchgeführt werden.It was also found that the depolymerization with the help of these catalysts It is particularly easy for the depolymerization products to be of greater purity accumulate and that only a little residue is formed. The depolymerization can take place at continuous addition of polylactic acid can also be carried out continuously.
Für die folgenden Versuche wurde jeweils eine Handelsmilchsäure gleicher optischer Aktivität verwendet. Zur Bestimmung der spezifischen Drehung [a] wurde eine 1 °/oige benzolische Lösung verwendet.A commercial lactic acid was used for each of the following experiments optical activity used. To determine the specific rotation [a] was a 1% benzene solution is used.
Beispiel 1 (a) 500 g optisch aktive, etwa 80 %ige 1(+)-Handelsmilchsäure werden in bekannter Weise durch Entwässerung in Polymilchsäure übergeführt. Anschließend wird in Gegenwart von 2 g Zinkoxyd unter Vakuum bei einer Badtemperatur von 210 bis 250°C die thermische Depolymerisation zu Lactid durchgeführt. Nach erfolgter Reinigung verbleiben 56,5 % der Theorie an optisch aktivem Lactid mit einem Erstarrungspunkt von 93°C und einer spezifischen Drehung [a] ö = -255°.Example 1 (a) 500 g of optically active, approximately 80% 1 (+) - commercial lactic acid are converted into polylactic acid by dehydration in a known manner. Afterward is in the presence of 2 g of zinc oxide under vacuum at a bath temperature of 210 Thermal depolymerization to lactide is carried out up to 250 ° C. After After cleaning, 56.5% of theory remain of optically active lactide with a freezing point of 93 ° C and a specific rotation [a] ö = -255 °.
(b) Ein in gleicher Weise durchgeführter Versuch, aber mit 2 g Blei(II)-oxyd als Depolymerisationskatalysator, ergibt nach Reinigung des Rohlactides eine 61 °/oige Ausbeute an Lactid mit einem Erstarrungspunkt von 92°C und einer spezifischen Drehung [a] ö = -265°.(b) An experiment carried out in the same way, but with 2 g of lead (II) oxide as a depolymerization catalyst, gives a 61 after purification of the crude lactide % Yield of lactide with a congealing point of 92 ° C and a specific Rotation [a] ö = -265 °.
Beispiel 2 Ein in gleicher Weise wie im Beispiel 1 durchgeführter Versuch, aber mit 2 g Zinn(II)-oxyd als Depolymerisationskatalysator, ergibt nach erfolgter Reinigung des Rohlactides eine 70 °/oige Ausbeute an Lactid mit einem Erstarrungspunkt von 96,5°C und einer spezifischen Drehung [a] = ö -290°.Example 2 One carried out in the same way as in Example 1 Experiment, but with 2 g of tin (II) oxide as the depolymerization catalyst, results in completed purification of the raw lactide a 70% yield of lactide with a Freezing point of 96.5 ° C and a specific rotation [a] = ö -290 °.
Beispiel 3 Ein in gleicher Weise wie im Beispiel 1 durchgeführter Versuch, aber mit 2 g Antimon(III)-oxyd als Depolymerisationskatalysator, ergibt nach erfolgter Reinigung des ROlAactides eine 65 °/oige Ausbeute an Lactid mit einem Erstarrungspunkt von 97,5°C und einer spezifischen Drehung [a] ö = -300°.Example 3 One carried out in the same manner as in Example 1 Experiment, but with 2 g of antimony (III) oxide as the depolymerization catalyst after purification of the ROlAactide, a 65% yield of lactide with one Freezing point of 97.5 ° C and a specific rotation [a] ö = -300 °.
Beispiel 4 Ein in gleicher Weise wie im Beispiel 1 durchgeführter Versuch; aber mit 2 g Eisen(III)-acetat als Depolymerisationskatalysator, ergibt nach erfolgter Reinigung des Rohlactides eine 63.o/oige Ausbeute an Lactid mit einem Erstarrungspunkt von 94,5°C und einer spezifischen Drehung [a] ö = -292,5°. Beispiel 5 Bei diesem Versuch wird als Ausgangsmaterial optisch aktives Lactid, F. 97°C, spezifische Drehung [a] ö = -297,5°, verwendet. Das Lactid wird in Milchsäure und anschließend in bekannter Weise in Polymilchsäure übergeführt. Die Depolymerisation erfolgt in Gegenwart von Eisen(II)-lactat. Aus dem Rohlactid wird durch Reinigung in 74o/oiger Ausbeute ein Lactid mit einem Erstarrungspunkt von 95°C und einer spezifischen Drehung [a] ö = -292,5° erhalten. Ähnliche Ergebnisse werden bei Verwendung von Eisenpulver oder Eisenchlorid erzielt.Example 4 One carried out in the same way as in Example 1 Attempt; but with 2 g of iron (III) acetate as the depolymerization catalyst, results after purification of the crude lactide, a 63% yield of lactide with a Freezing point of 94.5 ° C and a specific rotation [a] ö = -292.5 °. example 5 In this experiment, optically active lactide, mp 97 ° C, is used as the starting material. specific rotation [a] δ = -297.5 °, used. The lactide is converted into lactic acid and then converted into polylactic acid in a known manner. The depolymerization takes place in the presence of iron (II) lactate. The raw lactide becomes through cleaning a lactide with a solidification point of 95 ° C. and a specific one in 74% yield Rotation [a] ö = -292.5 ° obtained. Similar results are obtained using Iron powder or ferric chloride achieved.
Beispiel 6 60 g Polymilchsäure mit einer relativen Viskosität von 4,3, gemessen als 1 o/oige benzolische Lösung, werden in Gegenwart von 0,5 g Zinn(II)-oxyd bei 250°C depolymerisiert. Es werden 54 g inaktives Lactid erhalten.Example 6 60 g of polylactic acid with a relative viscosity of 4.3, measured as a 1% benzene solution, are added in the presence of 0.5 g of tin (II) oxide depolymerized at 250 ° C. 54 g of inactive lactide are obtained.
Claims (2)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DED30990A DE1083275B (en) | 1959-07-02 | 1959-07-02 | Process for the production of lactide |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DED30990A DE1083275B (en) | 1959-07-02 | 1959-07-02 | Process for the production of lactide |
Publications (1)
Publication Number | Publication Date |
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DE1083275B true DE1083275B (en) | 1960-06-15 |
Family
ID=7040733
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
DED30990A Pending DE1083275B (en) | 1959-07-02 | 1959-07-02 | Process for the production of lactide |
Country Status (1)
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Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3322791A (en) * | 1963-09-26 | 1967-05-30 | Ethicon Inc | Preparation of optically active lactides |
DE3632103A1 (en) * | 1986-09-20 | 1988-03-24 | Boehringer Ingelheim Kg | Process for the preparation of lactide |
EP0261572A1 (en) * | 1986-09-20 | 1988-03-30 | Boehringer Ingelheim Kg | Process for the production of lactide |
DE3708915A1 (en) * | 1987-03-19 | 1988-09-29 | Boehringer Ingelheim Kg | METHOD FOR PRODUCING LACTID |
US5247059A (en) * | 1992-01-24 | 1993-09-21 | Cargill, Incorporated | Continuous process for the manufacture of a purified lactide from esters of lactic acid |
US5247058A (en) * | 1992-01-24 | 1993-09-21 | Cargill, Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
US5258488A (en) * | 1992-01-24 | 1993-11-02 | Cargill, Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
US5274073A (en) * | 1992-01-24 | 1993-12-28 | Cargill, Incorporated | Continuous process for manufacture of a purified lactide |
US5338822A (en) * | 1992-10-02 | 1994-08-16 | Cargill, Incorporated | Melt-stable lactide polymer composition and process for manufacture thereof |
US5342969A (en) * | 1993-03-03 | 1994-08-30 | E. I. Du Pont De Nemours And Company | Recovery of hydroxycarboxylic acid values from poly(hydroxycarboxylic acids) |
US5665474A (en) * | 1992-10-02 | 1997-09-09 | Cargill, Incorporated | Paper having a melt-stable lactide polymer coating and process for manufacture thereof |
US5807973A (en) * | 1992-10-02 | 1998-09-15 | Cargill, Incorporated | Melt-stable lactide polymer nonwoven fabric and process for manufacture thereof |
US6005067A (en) * | 1992-01-24 | 1999-12-21 | Cargill Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
US6005068A (en) * | 1992-10-02 | 1999-12-21 | Cargill Incorporated | Melt-stable amorphous lactide polymer film and process for manufacture thereof |
US6326458B1 (en) | 1992-01-24 | 2001-12-04 | Cargill, Inc. | Continuous process for the manufacture of lactide and lactide polymers |
-
1959
- 1959-07-02 DE DED30990A patent/DE1083275B/en active Pending
Cited By (33)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3322791A (en) * | 1963-09-26 | 1967-05-30 | Ethicon Inc | Preparation of optically active lactides |
DE3632103A1 (en) * | 1986-09-20 | 1988-03-24 | Boehringer Ingelheim Kg | Process for the preparation of lactide |
EP0261572A1 (en) * | 1986-09-20 | 1988-03-30 | Boehringer Ingelheim Kg | Process for the production of lactide |
DE3708915A1 (en) * | 1987-03-19 | 1988-09-29 | Boehringer Ingelheim Kg | METHOD FOR PRODUCING LACTID |
US5247059A (en) * | 1992-01-24 | 1993-09-21 | Cargill, Incorporated | Continuous process for the manufacture of a purified lactide from esters of lactic acid |
US5247058A (en) * | 1992-01-24 | 1993-09-21 | Cargill, Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
US5258488A (en) * | 1992-01-24 | 1993-11-02 | Cargill, Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
US5274073A (en) * | 1992-01-24 | 1993-12-28 | Cargill, Incorporated | Continuous process for manufacture of a purified lactide |
US6326458B1 (en) | 1992-01-24 | 2001-12-04 | Cargill, Inc. | Continuous process for the manufacture of lactide and lactide polymers |
US6277951B1 (en) | 1992-01-24 | 2001-08-21 | Cargill, Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
US5357035A (en) * | 1992-01-24 | 1994-10-18 | Cargill, Incorporated | Continuous process for manufacture of lactide polymers with purification by distillation |
US6005067A (en) * | 1992-01-24 | 1999-12-21 | Cargill Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
US5665474A (en) * | 1992-10-02 | 1997-09-09 | Cargill, Incorporated | Paper having a melt-stable lactide polymer coating and process for manufacture thereof |
US5475080A (en) * | 1992-10-02 | 1995-12-12 | Cargill, Incorporated | Paper having a melt-stable lactide polymer coating and process for manufacture thereof |
US5539081A (en) * | 1992-10-02 | 1996-07-23 | Cargill, Incorporated | Melt-stable lactide polymer composition and process for manufacture thereof |
US5585191A (en) * | 1992-10-02 | 1996-12-17 | Cargill, Incorporated | Melt-stable amorphous lactide polymer film and process for manufacture thereof |
US5484881A (en) * | 1992-10-02 | 1996-01-16 | Cargill, Inc. | Melt-stable amorphous lactide polymer film and process for manufacturing thereof |
US5763564A (en) * | 1992-10-02 | 1998-06-09 | Cargill, Incorporated | Melt-stable lactide polymer composition and process for manufacture thereof |
US5773562A (en) * | 1992-10-02 | 1998-06-30 | Cargill, Incorporated | Melt-stable semi-crystalline lactide polymer film and process for manufacture thereof |
US5798436A (en) * | 1992-10-02 | 1998-08-25 | Cargill, Incorporated | Melt-stable amorphous lactide polymer film and process for manufacture thereof |
US5807973A (en) * | 1992-10-02 | 1998-09-15 | Cargill, Incorporated | Melt-stable lactide polymer nonwoven fabric and process for manufacture thereof |
US5852166A (en) * | 1992-10-02 | 1998-12-22 | Cargill, Incorporated | Paper having a melt-stable lactide polymer coating and process for manufacture thereof |
US5981694A (en) * | 1992-10-02 | 1999-11-09 | Cargill, Incorporated | Melt-stable lactide polymer composition and process for manufacture thereof |
US5536807A (en) * | 1992-10-02 | 1996-07-16 | Cargill, Incorporated | Melt-stable semi-crystalline lactide polymer film and process for manufacture thereof |
US6005068A (en) * | 1992-10-02 | 1999-12-21 | Cargill Incorporated | Melt-stable amorphous lactide polymer film and process for manufacture thereof |
US6093791A (en) * | 1992-10-02 | 2000-07-25 | Cargill, Incorporated | Melt-stable semi-crystalline lactide polymer film and process for manufacture thereof |
US6111060A (en) * | 1992-10-02 | 2000-08-29 | Cargill, Incorporated | Melt-stable lactide polymer nonwoven fabric and process for manufacture thereof |
US6121410A (en) * | 1992-10-02 | 2000-09-19 | Cargill, Incorporated | Melt-stable semi-crystalline lactide polymer film and process for manufacture thereof |
US6143863A (en) * | 1992-10-02 | 2000-11-07 | Cargill, Incorporated | Melt-stable lactide polymer composition and process for manufacture thereof |
US6207792B1 (en) | 1992-10-02 | 2001-03-27 | Cargill, Incorporated | Melt-stable amorphous lactide polymer film and process for manufacture thereof |
US6355772B1 (en) | 1992-10-02 | 2002-03-12 | Cargill, Incorporated | Melt-stable lactide polymer nonwoven fabric and process for manufacture thereof |
US5338822A (en) * | 1992-10-02 | 1994-08-16 | Cargill, Incorporated | Melt-stable lactide polymer composition and process for manufacture thereof |
US5342969A (en) * | 1993-03-03 | 1994-08-30 | E. I. Du Pont De Nemours And Company | Recovery of hydroxycarboxylic acid values from poly(hydroxycarboxylic acids) |
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