US4950815A
Expired / Lapsed
US
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Tetrafluoroethane isomerization
Assignee: Imperial Chemical Industries Ltd
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Filing: 1989-10-20
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Granted: 1990-08-21
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Expires: 2009-10-20
Abstract
Abstract A method for the preparation of 1,1,1,2-tetrafluoroethane whereby 1,1,2,2-tetrafluoroethane is contacted with the fluorination catalyst at elevated temperature to effect isomerisation.
Inventors
- 👤 Geoffrey J. Moore
- 👤 Helen M. Massey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:59
CPC Classifications
C; C07; C07C; C07C17/00; C07C17/35; C07C17/358
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
23 words
A method for the preparation of 1,1,1,2-tetrafluoroethane which comprises contacting 1,1,2,2-tetrafluoroethane with a fluorination catalyst at an elevated temperature whereby to effect isomerisation.
Claim 2
Independent Claim
23 words
A method for the preparation of 1,1,1,2-tetrafluoroethane which comprises contacting 1,1,2,2-tetrafluoroethane with a fluorination catalyst at an elevated temperature whereby to effect isomerisation.
Claim 3
Dependent Claim
11 words
A method according to claim 1 wherein the catalyst comprises chromia.
Claim 4
Dependent Claim
12 words
A method according to claim 2 wherein the catalyst comprises pre-fluorinated chromia.
Claim 5
Independent Claim
21 words
A method according to any preceding claim wherein the temperature is in the range from about 300° to about 900° C.
Claim 6
Dependent Claim
20 words
A method according to claim 4 wherein the temperature is in the range from about 300° to about 550° C.
Claim 7
Dependent Claim
18 words
A method according to claim 5 wherein the temperature is in the range from 350° to 500° C.
Claim 8
Dependent Claim
18 words
A method according to claim 6 wherein the temperature is in the range from 400° to 450° C.
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) | 1993-08-20 | 1994-02-19 | 1994-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-20 | 1998-02-19 | 1998-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-20 | 2002-02-19 | 2002-08-21 | $7700.00 | Window Closed / Lapsed |