US2523496A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing xanthine and methylated xanthines
Assignee: Individual
•
Filing: 1948-10-21
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Granted: 1950-09-26
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Expires: 1968-10-21
Abstract
No abstract record available.
Inventors
- 👤 Kenneth N Campbell
- 👤 Barbara K Campbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:07
CPC Classifications
C; C07; C07D; C07D473/00; C07D473/02; C07D473/04; C07D473/06; C07D473/08; C07D473/12
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
150 words
IN THE PREPARATION OF CAFFEINE, THE METHOD WHICH COMPRISES: CONDENSING CYANOACETIC ACID AND METHYL UREA HAVING NOT MORE THAN TWO METHYL GROUPS WITH NOT MORE THAN ONE METHYL GROUP ATTACHED TO A SINGLE NITROGEN ATOM TO FORM A METHYLATED CYANOACETYL-UREA; TRANSFORMING SAID CYANOACETYL-UREA IN THE PRESENCE OF AN ALKALI METAL NITRITE AND THEN A REDUCING AGENT INTO A METHYLATED 2,6-DIOXY-4,5- DIAMINOPYRIMIDINE; TREATED SAID PYRIMIDINE DERIVATIVE WITH FORMIC ACID AND THEN WITH AN ALKALI METAL HYDROXIDE TO FORM AND CLOSE AN IMIDAZOLE RING CONNECTING THE CARBON ATOMS IN THE 4 AND 5 POSITIONS, SAID CARBON ATOMS BEING JOINED BY A DOUBLE BOND; AND REACTING WITH A METHYLATED AGENT TO INTRODUCE A METHYL GROUP AT THE NITROGEN ATOM IN THE 7 POSITION AND A METHYL GROUP AT ONE OF THE NITROGEN ATOMS IN THE 1,3 POSITION WHEN SAID ONE NITROGEN ATOM IS NOT ALREADY ATTACHED TO A METHYL GROUP TO FORM CAFFEINE.
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) | 1953-09-25 | 1954-03-27 | 1954-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-09-25 | 1958-03-27 | 1958-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-09-25 | 1962-03-27 | 1962-09-26 | $7700.00 | Window Closed / Lapsed |