US5053522A
Expired / Lapsed
US
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Process for the preparation of lactide
Assignee: Boehringer Ingelheim GmbH
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Filing: 1989-05-05
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Granted: 1991-10-01
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Expires: 2009-05-05
Abstract
Abstract The invention relates to a process for the preparation of lactide, in particular of optically pure L(-)- or D(+)-lactide, on an industrial scale.
Inventors
- 👤 Manfred Muller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:20
CPC Classifications
C; C07; C07D; C07D319/00; C07D319/10; C07D319/12; C07C; C07C59/00; C07C59/01; C07C59/10; C08; C08G; C08G63/00; C08G63/02; C08G63/06
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
103 words
A continuous or semicontinuous process for preparing L(-) or D(+)-lactide of substantial optical purity, wherein L(-) -polylactic acid is employed as the starting material to make L(-) lactide and D(+)-polylactic acid is employed as the starting material to make D(+)-lactide, wherein the starting materials are of 90% optical purity, and wherein the polylactic acid is heated to about 130 ° to 230° C., under reduced pressure, in the presence of about 0.05 to 1.0 per cent by weight of a catalyst selected from the group consisting of tin dust, tin halide and organic tin compounds derived from C 1 -C 20 carboxylic acids.
Claim 2
Dependent Claim
103 words
A continuous or semicontinuous process for preparing L(-) or D(+)-lactide of substantial optical purity, wherein L(-) -polylactic acid is employed as the starting material to make L(-) lactide and D(+)-polylactic acid is employed as the starting material to make D(+)-lactide, wherein the starting materials are of 90% optical purity, and wherein the polylactic acid is heated to about 130 ° to 230° C., under reduced pressure, in the presence of about 0.05 to 1.0 per cent by weight of a catalyst selected from the group consisting of tin dust, tin halide and organic tin compounds derived from C 1 -C 20 carboxylic acids.
Claim 3
Dependent Claim
71 words
The continuous or semicontinuous process of claim 1 wherein the organic tin compound is of the formula ##STR3## wherein X is a branched or unbranched alkyl, hydroxyalkyl or alkenyl radical having up to 19 carbon atoms or a naphthyl radical, or an organic tin compound of the formula ##STR4## wherein Y is a branched or unbranched alkyl, hydroxyalkyl or alkenyl radical having up to 18 carbon atoms or a phenyl radical.
Claim 4
Dependent Claim
42 words
The continuous or semicontinuous process of claim 2, wherein the tin compound is selected from the group consisting of tin lactate, tin tantrate, tin oxalate, tin dicaprylate, tin dilaurate, tin dipalmitate, tin distearate, tin dioleate, tin α-naphthoate, tin β-naphthoate and tin dioctoate.
References Cited (Backward Citations)
US1095205A
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GB1108720A
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US4157330A
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US4165321A
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Cited
US4789726A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-30 | 1995-04-01 | 1995-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-30 | 1999-04-01 | 1999-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-30 | 2003-04-01 | 2003-10-01 | $7700.00 | Window Closed / Lapsed |