US5089632A
Expired / Lapsed
US
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Process for preparing cyclic esters using a fluorocarbon
Assignee: Ecological Chemical Products
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Filing: 1991-01-30
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Granted: 1992-02-18
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Expires: 2011-01-30
Abstract
Abstract Process for preparing high purity solvent-free cyclic esters from alpha hydroxycarboxylic acids via an intermediate oligomer wherein a fluorocarbon or a mixture of fluorocarbons is employed to strip the ester from the oligomer as well as a refrigerant to quench lactide from a gaseous reaction stream comprising, besides cyclic ester, unconverted alpha-hydroxycarboxylic acid and water.
Inventors
- 👤 Donald C. Paul
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:27
CPC Classifications
C; C07; C07D; C07D319/00; C07D319/10; C07D319/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
139 words
In a process for preparing a cyclic ester having the formula: ##STR3## wherein R 1 and R 2 are independently hydrogen or an aliphatic hydrocarbyl radical having 1 to 6 carbon atoms, by depolymerizing the oligomer resulting from the pyrolysis of an alpha-hydroxycarboxylic acid in a reaction zone, the improvement which comprises sweeping a gaseous fluorocarbon through the so as to create a large interfacial area with the oligomer and so as reaction zone to form a gas product stream comprising at least one member of the following group: water, cyclic ester and unpolymerized alpha-hydroxycarboxylic acid; contacting the gas product stream with a liquefied fluorocarbon, in the absence of an organic polar scrubbing solvent, to precipitate cyclic ester from the gas product stream; vaporizing at least a portion of the liquefied fluorocarbon, and; collecting the cyclic ester which precipitated.
Claim 2
Dependent Claim
139 words
In a process for preparing a cyclic ester having the formula: ##STR3## wherein R 1 and R 2 are independently hydrogen or an aliphatic hydrocarbyl radical having 1 to 6 carbon atoms, by depolymerizing the oligomer resulting from the pyrolysis of an alpha-hydroxycarboxylic acid in a reaction zone, the improvement which comprises sweeping a gaseous fluorocarbon through the so as to create a large interfacial area with the oligomer and so as reaction zone to form a gas product stream comprising at least one member of the following group: water, cyclic ester and unpolymerized alpha-hydroxycarboxylic acid; contacting the gas product stream with a liquefied fluorocarbon, in the absence of an organic polar scrubbing solvent, to precipitate cyclic ester from the gas product stream; vaporizing at least a portion of the liquefied fluorocarbon, and; collecting the cyclic ester which precipitated.
Claim 3
Dependent Claim
109 words
In a process for preparing lactide by depolymerizing the oligomer resulting from the pyrolysis of lactic acid in a reaction zone, the improvement which comprises sweeping a gaseous fluorocarbon through the so as to create a large interfacial area with the oligomer and so as reaction zone to form a gas product stream comprising at least one member of the following group: water, lactide and unpolymerized lactic acid; contacting the gas product stream with a liquefied fluorocarbon, in the absence of an organic polar scrubbing solvent to precipitate lactide from the gas product stream; vaporizing at least a portion of the liquified fluorocarbon, and; collecting the lactide which precipitated.
Claim 4
Dependent Claim
109 words
In a process for preparing lactide by depolymerizing the oligomer resulting from the pyrolysis of lactic acid in a reaction zone, the improvement which comprises sweeping a gaseous fluorocarbon through the so as to create a large interfacial area with the oligomer and so as reaction zone to form a gas product stream comprising at least one member of the following group: water, lactide and unpolymerized lactic acid; contacting the gas product stream with a liquefied fluorocarbon, in the absence of an organic polar scrubbing solvent to precipitate lactide from the gas product stream; vaporizing at least a portion of the liquified fluorocarbon, and; collecting the lactide which precipitated.
Claim 5
Dependent Claim
27 words
The process of claim 1 wherein any fluorocarbon exiting the process in the vapor phase is condensed to its liquid state and recycled to the contacting step.
Claim 6
Dependent Claim
23 words
The process of claim 1 wherein unvaporized fluorocarbon from the contacting step is volatilized to a gas and fed into the reaction zone.
Claim 7
Dependent Claim
29 words
The process of claim 2 wherein the liquefied fluorocarbon feed rate to the contacting step is controlled as to result in no residual liquid fluorocarbon in the lactide product.
Claim 8
Dependent Claim
19 words
The process of claim 2 wherein the liquefied fluorocarbon is introduced to the contacting step through an atomizing means.
Claim 9
Dependent Claim
27 words
The process of claim 6 wherein the flow from the atomizing means is directed counter-current to the flow of the gas product stream from the reaction zone.
Claim 10
Dependent Claim
35 words
The process of claim 1 wherein the fluorocarbon comprises at least one compound having the formula ##STR4## wherein all "A"s are independently hydrogen, chlorine or fluorine, at least one being fluorine and n=1 through 4.
Claim 11
Dependent Claim
68 words
The process of claim 1 wherein said fluorocarbons comprise at least one member of the following group: CCl 3 F, CCl 2 F 2 , CClF 3 , CBrF 3 , CF 4 , CHCl 2 F, CHClF 2 , CHF 3 , CCl 2 F-CCl 2 F, CCl 2 F-CClF 2 , CClF 2 -CClF 2 , CClF 2 CF 3 and CF 3 CF 3 .
Claim 12
Dependent Claim
18 words
The process of claim 1 wherein said fluorocarbons possess a vapor pressure of at least about 1.0 atmosphere.
Claim 13
Dependent Claim
14 words
The process of claim 1 wherein said fluorocarbons possess a low ozone depletion potential.
Claim 14
Dependent Claim
14 words
The process of claim 1 wherein said fluorocarbons comprise CClF 2 CClF 2 .
Claim 15
Dependent Claim
14 words
The process of claim 1 wherein said fluorocarbons comprise CH 2 FCF 3 .
Claim 16
Dependent Claim
12 words
The process of claim 1 wherein said fluorocarbons comprise CHClFCF 3 .
Claim 17
Dependent Claim
14 words
The process of claim 1 wherein said fluorocarbons comprise CClF 2 CH 3 .
Claim 18
Dependent Claim
14 words
The process of claim 1 wherein said fluorocarbons comprise C 4 F 8 .
Claim 19
Dependent Claim
16 words
The process of claim 1, wherein said fluorocarbons comprise a blend of HCFC-22, HFC-152a and HCFC-124.
Claim 20
Dependent Claim
23 words
The process of claim 1, wherein the fluorocarbon which is used in the sweeping step and the liquefied fluorocarbon comprises a fluorocarbon blend.
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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) | 1995-02-17 | 1995-08-19 | 1996-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-17 | 1999-08-19 | 2000-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-17 | 2003-08-19 | 2004-02-18 | $7700.00 | Window Closed / Lapsed |