Patent US2353187A successfully refreshed from Google Patents.
Patent US3694466A successfully refreshed from Google Patents.
US3694466A
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Process for the preparation of 2,5-dimethyl-4,5-dihydrofuran-3-ol-4-one
Assignee: GEORGE H BUCHI
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Filing: 1970-02-19
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Granted: 1972-09-26
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Expires: 1990-02-19
Abstract
Abstract 2,5-DIMETHYL-4,5-DIHYDROFURAN-3-OL-4-ONE IS PREPARED BY CATALYTIC CYCLISATION OF HEXANE-3,4-DIOL-2,5-DIONE.
Inventors
- 👤 George H Buchi
- 👤 Edouard Demole
- 👤 Albert Eschenmoser
- 👤 Alan F Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:47
CPC Classifications
C; C07; C07D; C07D307/00; C07D307/02; C07D307/34; C07D307/56; C07D307/60; A; A23; A23L; A23L27/00; A23L27/20; A23L27/205; A23L27/2052; C07C; C07C29/00; C07C29/36; C07C29/38; C07C29/42; C07C45/00; C07C45/40; C07C45/56; C07C45/57; C07C45/59; C07C45/61; C07C45/67; C07C45/68; C07C45/72; C07C49/00; C07C49/04; C07C49/17
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
24 words
Process according to claim 1 which comprises using as a cyclization catalyst a salt of an organic carboxylic acid with an organic nitrogen base.
Claim 2
Dependent Claim
14 words
Process according to claim 2 which comprises using piperidine acetate as a cyclization catalyst.
Claim 3
Dependent Claim
20 words
Process according to claim 1 which using, as a cyclization catalyst, an alKali metal salt of a polybasic mineral acid.
Claim 4
Dependent Claim
25 words
Process according to claim 1 which comprises using, as a cyclization catalyst, sodium carbonate, sodium bicarbonate or a mixture of sodium orthophosphate, monohydrogenphosphate and dihydrogenphosphate.
Claim 5
Dependent Claim
25 words
Process according to claim 1, which comprises carrying out the cyclization in water at a pH comprised between 6 and 9 and at reflux temperature.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-26 | 1976-03-27 | 1976-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-26 | 1980-03-27 | 1980-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-26 | 1984-03-27 | 1984-09-26 | $7700.00 | Window Closed / Lapsed |