Patent US5492851A successfully refreshed from Google Patents.
Patent US5274127A successfully refreshed from Google Patents.
US5274127A
Expired / Lapsed
US
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Lactide production from dehydration of aqueous lactic acid feed
Assignee: Battelle Development Corp
•
Filing: 1990-09-18
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Granted: 1993-12-28
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Expires: 2010-09-18
Abstract
Abstract The present invention is directed to a method for making L-lactide from aqueous L-lactic acid. Aqueous lactic acid feed for present purposes comprehends an aqueous mixture of one or more of L 1 A, L 2 A, and L 3 A, optionally with LD being present. L-lactic acid is the preferred feed configuration for making L-lactide, and is to be understood even though the configuration symbol is not used throughout this application. Aqueous lactic acid feed is treated for removal of water therefrom until a degree of polymerization (DP) not substantially above about 2 is reached. The treatment then is ceased to produce a crude LD product. LD then is separated from the crude LD product. A preferred treatment involves heating the feed at elevated temperature to remove water. LD can be separated from the crude LD product by a variety of techniques to produce an LD-depleted product. This LD-depleted product, optionally augmented with additional aqueous lactic acid and/or water then can be readmitted to the process for making additional lactide. This cyclic or recycle process embodiment of the present invention enables very high lactide conversions to be realized.
Inventors
- 👤 Richard G. Sinclair
- 👤 Richard A. Markle
- 👤 Russell K. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:03
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; C07; C07D; C07D319/00; C07D319/10; C07D319/12; C08L; C08L67/00; C08L67/04; C09; C09D; C09D167/00; C09D167/04; B; B01; B01J; B01J2219/00; B01J2219/19; B01J2219/194; B01J2219/1941; B01J2219/1942; C08J2367/00; C08J2367/04
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
63 words
A method for making lactide from aqueous lactic acid feed enriched in L 1 A and L 2 A, which comprises: treating said feed to remove water therefrom until the treated feed has a DP not substantially above about 2 as measured by titration, and then ceasing said treating to make a crude LD product; and separating LD from said crude LD product.
Claim 2
Independent Claim
63 words
A method for making lactide from aqueous lactic acid feed enriched in L 1 A and L 2 A, which comprises: treating said feed to remove water therefrom until the treated feed has a DP not substantially above about 2 as measured by titration, and then ceasing said treating to make a crude LD product; and separating LD from said crude LD product.
Claim 3
Dependent Claim
33 words
The method of claim 1 wherein said treating is selected from the group consisting of heating at elevated temperature, addition of a water-getter which preferentially reacts with water, and using an osmotic membrane.
Claim 4
Dependent Claim
19 words
The method of claim 2 wherein said water getter is one or more of an anhydride or a ketal.
Claim 5
Dependent Claim
24 words
The method of claim 1 wherein said separating is by one or more of cold water washing, fractional distillation, solvent extraction, and solvent recrystallization.
Claim 6
Dependent Claim
12 words
The method of claim 4 wherein said separation technique is by distillation.
Claim 7
Dependent Claim
15 words
The method of claim 5 wherein said distillation is conducted utilizing a codistillation organic solvent.
Claim 8
Dependent Claim
13 words
The method of claim 6 wherein said codistillation solvent comprises an alkyl benzene.
Claim 9
Dependent Claim
23 words
The method of claim 7 wherein said alkyl benzene is selected from the group consisting of dodecyl benzene, tridecyl benzene, and mixtures thereof.
Claim 10
Dependent Claim
31 words
The method of claim 1 wherein the crude LD product from which LD has been separated is reconstituted to have a DP of less than 2 and recycled for additional treating.
Claim 11
Independent Claim
73 words
A method for making lactide from aqueous lactic acid feed enriched in L 1 A and L 2 A, and depleted in higher oligomeric L n A species, which comprises: subjecting said feed to heating at elevated temperature to remove water therefrom until the heated feed has a DP not substantially above about 2, and then ceasing said heating to produce a crude LD product; and separating LD from said crude LD product.
Claim 12
Independent Claim
73 words
A method for making lactide from aqueous lactic acid feed enriched in L 1 A and L 2 A, and depleted in higher oligomeric L n A species, which comprises: subjecting said feed to heating at elevated temperature to remove water therefrom until the heated feed has a DP not substantially above about 2, and then ceasing said heating to produce a crude LD product; and separating LD from said crude LD product.
Claim 13
Dependent Claim
12 words
The method of claim 10 wherein said heating is conducted under vacuum.
Claim 14
Dependent Claim
17 words
The method of claim 10 wherein said heating is at a temperature ranging from about 150°-225° C.
Claim 15
Dependent Claim
31 words
The method of claim 10 wherein the crude LD product from which LD has been separated is reconstituted to have a DP of less than 2 and recycled for additional treating.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-12-27 | 1997-06-28 | 1997-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-27 | 2001-06-28 | 2001-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-27 | 2005-06-28 | 2005-12-28 | $7700.00 | Window Closed / Lapsed |