US5011946A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing D,L-Lactide
Assignee: Boehringer Ingelheim GmbH
•
Filing: 1990-05-25
•
Granted: 1991-04-30
•
Expires: 2010-05-25
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
2026-11-04 11:32
CPC Classifications
C; C07; C07D; C07D319/00; C07D319/10; C07D319/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
78 words
A process for preparing D,L-lactide which comprises: (a) dissolving D-lactide and L-lactide in a solvent or a mixture of solvents capable of forming an azeotrope with water, to produce a starting solution; (b) filtering the starting solution; (c) concentrating the filtered starting solution, to produce a residual solution; (d) cooling the residual solution until a crystalline precipitate of D,L-lactide forms; (e) separating the crystalline precipitate from the remainder of the residual solution; and (f) drying the crystalline precipitate.
Claim 2
Dependent Claim
78 words
A process for preparing D,L-lactide which comprises: (a) dissolving D-lactide and L-lactide in a solvent or a mixture of solvents capable of forming an azeotrope with water, to produce a starting solution; (b) filtering the starting solution; (c) concentrating the filtered starting solution, to produce a residual solution; (d) cooling the residual solution until a crystalline precipitate of D,L-lactide forms; (e) separating the crystalline precipitate from the remainder of the residual solution; and (f) 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
26 words
A process as recited in claim 2 wherein steps (a) and (b) are each conducted at a temperature between about 40° C. and about 70° C.
Claim 5
Dependent Claim
21 words
A process as recited in claim 3 wherein steps (c) and (f) are each conducted at a pressures below atmospheric pressure.
Claim 6
Dependent Claim
19 words
A process as recited in claims 4 wherein in step (c) the filtered starting solution is concentrated by evaporation.
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) | 1994-04-29 | 1994-10-29 | 1995-04-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-29 | 1998-10-29 | 1999-04-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-29 | 2002-10-29 | 2003-04-30 | $7700.00 | Window Closed / Lapsed |