US5149833A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing D,L-Lactide
Assignee: Boehringer Ingelheim GmbH
•
Filing: 1991-02-05
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Granted: 1992-09-22
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Expires: 2011-02-05
Abstract
Abstract An improved process for the preparation of D,L-Lactide which can be used directly in polymerization reactions.
Inventors
- 👤 Joachim Hess
- 👤 Klaus R. Muller
- 👤 Manfred Muller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:25
CPC Classifications
C; C07; C07D; C07D319/00; C07D319/10; C07D319/12
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
119 words
A process for preparing D,L-lactide which comprises a) dissolving D-lactide in a first volume of a solvent or a mixture of solvents capable of forming an azeotrope with water, to produce a first solution; b) filtering the first solution; c) dissolving L-lactide in a second volume of the solvent or mixture of solvents, to produce a second solution; d) filtering the second solution; e) combining the filtered first solution and the filtered second solution, to produce a starting solution; f) concentrating the starting solution, to produce a residual solution; g) cooling the residual solution until a crystalline precipitate of D,L-lactide forms; h) separating the crystalline precipitate from the remainder of the residual solution; and i) drying the crystalline precipitate.
Claim 2
Dependent Claim
119 words
A process for preparing D,L-lactide which comprises a) dissolving D-lactide in a first volume of a solvent or a mixture of solvents capable of forming an azeotrope with water, to produce a first solution; b) filtering the first solution; c) dissolving L-lactide in a second volume of the solvent or mixture of solvents, to produce a second solution; d) filtering the second solution; e) combining the filtered first solution and the filtered second solution, to produce a starting solution; f) concentrating the starting solution, to produce a residual solution; g) cooling the residual solution until a crystalline precipitate of D,L-lactide forms; h) separating the crystalline precipitate from the remainder of the residual solution; and i) drying the crystalline precipitate.
Claim 3
Dependent Claim
12 words
A process as recited in claim 1 wherein the solvent is toluene.
Claim 4
Dependent Claim
24 words
A process as recited in claim 2 wherein steps a)-d) are each conducted at a temperature between about 40° C. to about 70° C.
Claim 5
Dependent Claim
21 words
A process as recited in claim 3 wherein steps f) and i) are each conducted at a pressure below atmospheric pressure.
Claim 6
Dependent Claim
18 words
A process as recited in claim 4 wherein in step f, the starting solution is concentrated by evaporation.
Claim 7
Dependent Claim
18 words
A process as recited in claim 1 wherein the first volume is about equal to the second volume.
Claim 8
Dependent Claim
28 words
A process as recited in claim 6 wherein the concentration of D-lactide in the first solution is about equal to the concentration of L-lactide in the second solution.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-09-22 | 1996-03-23 | 1996-09-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-09-22 | 2000-03-23 | 2000-09-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-09-22 | 2004-03-23 | 2004-09-22 | $7700.00 | Window Closed / Lapsed |